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WO1998039770A1 - Thin-film magnetic recording head manufacture - Google Patents

Thin-film magnetic recording head manufacture Download PDF

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Publication number
WO1998039770A1
WO1998039770A1 PCT/US1998/003964 US9803964W WO9839770A1 WO 1998039770 A1 WO1998039770 A1 WO 1998039770A1 US 9803964 W US9803964 W US 9803964W WO 9839770 A1 WO9839770 A1 WO 9839770A1
Authority
WO
WIPO (PCT)
Prior art keywords
structural element
structural
marker
layer
particle beam
Prior art date
Application number
PCT/US1998/003964
Other languages
French (fr)
Inventor
Randall Grafton Lee
Charles J. Libby
Gregory J. Athas
Russell Mello
Original Assignee
Micrion Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US08/810,837 external-priority patent/US6004437A/en
Application filed by Micrion Corporation filed Critical Micrion Corporation
Priority to AU66752/98A priority Critical patent/AU6675298A/en
Publication of WO1998039770A1 publication Critical patent/WO1998039770A1/en

Links

Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127Structure or manufacture of heads, e.g. inductive
    • G11B5/33Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
    • G11B5/39Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
    • G11B5/3903Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects using magnetic thin film layers or their effects, the films being part of integrated structures
    • G11B5/3967Composite structural arrangements of transducers, e.g. inductive write and magnetoresistive read
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127Structure or manufacture of heads, e.g. inductive
    • G11B5/187Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
    • G11B5/1871Shaping or contouring of the transducing or guiding surface
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127Structure or manufacture of heads, e.g. inductive
    • G11B5/31Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3109Details
    • G11B5/3116Shaping of layers, poles or gaps for improving the form of the electrical signal transduced, e.g. for shielding, contour effect, equalizing, side flux fringing, cross talk reduction between heads or between heads and information tracks
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127Structure or manufacture of heads, e.g. inductive
    • G11B5/31Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3163Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional layers for masking, using energy or particle beams for shaping the structure or modifying the properties of the basic layers
    • G11B5/3166Testing or indicating in relation thereto, e.g. before the fabrication is completed
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/305Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating, or etching
    • H01J37/3053Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating, or etching for evaporating or etching
    • H01J37/3056Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating, or etching for evaporating or etching for microworking, e. g. etching of gratings or trimming of electrical components
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/30Electron or ion beam tubes for processing objects
    • H01J2237/304Controlling tubes
    • H01J2237/30433System calibration
    • H01J2237/30438Registration

Definitions

  • This invention relates to apparatus and methods for manufacturing improved thin-film magnetic recording transducers, commonly referred to as recording transducers. More specifically, it relates to a focused particle beam system for milling a portion of a pole-tip assembly of the recording transducer without irradiating a sensitive structure, e.g. a read head, of the recording transducer.
  • a recording transducer includes a write head and a read head.
  • the recording transducer has an air bearing surface that passes adjacent to a recording medium, such as a magnetic disk.
  • the portions of the recording transducer, including portions of the write head and of the read head, that are proximate to the air bearing surface form a small, precisely shaped pole-tip assembly.
  • the size and shape of the pole-tip assembly which include features on the order of one-half a micron, in part determine the magnetic field pattern produced by the recording transducer. This magnetic field pattern effects how narrowly the recording transducer can record data tracks on the magnetic media of magnetic memory storage devices, such as computer hard disks, and digital data tape drives.
  • Thinner data tracks allow a storage device to store more data tracks per area of media and therefore more data per device. Accordingly, precisely forming the pole-tip assembly of the recording transducer results in an increase in the total data storage capacity of a magnetic memory device. Manufacturers seek to form the geometry of a pole-tip assembly with high precision, and consequently achieve pole-tip assemblies capable of providing magnetic field patterns suitable for writing narrow tracks of recorded data.
  • lithographic techniques deposit alternating layers of conductive and insulating materials onto a substrate by an evaporation, sputtering, plating, or other deposition technique that provides precise control of the deposition thicknesses.
  • Chemical etching, reactive ion etching (RIE), or other techniques shape and form the deposited layers into a pole-tip assembly having the desired geometry.
  • RIE reactive ion etching
  • lithographic techniques work sufficiently well to provide pole- tip assemblies having feature sizes suitable for current data storage capacity, these lithographic techniques are limited as to the small feature sizes that they can produce.
  • present photolithographic techniques require precise application of photoresist layers.
  • the photoresist layer is applied to produce a topology that includes voids having aspect ratios of 10: 1 or larger.
  • Such topologies are difficult to achieve reliably, at the desired small sizes, using such a photoresist technique.
  • MRS Magneto- Resistive Stripe
  • FIB focused ion beam
  • the properties of a read head can be altered during irradiation by a focused ion beam (FIB).
  • FIB focused ion beam
  • One embodiment of the invention precisely forms a pole-tip assembly by milling a second structural element without irradiating a first structural element.
  • the invention avoids irradiating the first structural element by placing a first marker element, which can be imaged and/or damaged, in the same layer of a multi-layer lithographically fabricated device as the first structural element.
  • the marker element has a fixed spatial relationship to the first structural element.
  • the focused particle beam system mills the second structural element to produce a desired pole-tip configuration.
  • these methods and apparatus produce an improved recording head capable of higher storage density than prior art techniques.
  • the invention provides lithographic methods and apparatus for manufacturing improved thin-film recording heads.
  • the invention provides methods and apparatus for employing a focused particle beam to mill a recording head pole-tip assembly without irradiating a sensitive structure, e.g. a read head, of the pole- tip assembly.
  • a focused particle beam for practice of the invention can include an ion beam, electron beam, x-ray beam, optical beam or other similar source of directable radiant energy.
  • One embodiment of the lithographic method includes the following steps: i) pattern, in a common first lithographic layer, a first structural element and, at a known distance and direction, a first marker element; and ii) pattern, in a common second lithographic layer, a second structural element and a second marker element.
  • the above patterning steps provide the structural elements and the marker elements in a spatial arrangement such that they intersect a geometrical surface that extends transversely to the first and second lithographic layers. Consequently, viewing the first marker element and at least one of the second structural element or the second marker element, at the geometrical surface, provides information for locating the second structural element relative to the first structural element.
  • the second structural element and the second marker element are the same element.
  • the second marker element is located at a known distance and direction relative to the second structural element.
  • One embodiment of the process described above provides a multi-layer lithographically fabricated device including a first and second layer.
  • the first layer has a first structural element, and, at a known distance and direction relative thereto, a first marker element.
  • the second layer has a second structural element, and, a second marker element.
  • the structural and marker elements intersect a geometrical surface that extends transversely to the first and second layers so that viewing the first marker element and at least one of the second structural element and the second marker element, at the geometrical surface, provides information for locating the second structural element relative to the first structural element.
  • the second structural element and the second marker element are the same element.
  • the second marker element is located at a known distance and direction relative to the second structural element.
  • the invention provides methods and apparatus for employing a focused particle beam system to image marker elements on a multi-layer lithographically fabricated device containing the structure for a magnetic recording head. These processes further employ a processor to generate milling signals based on the physical location of the marker elements as determined from an imaging step. Those signals direct a focused particle beam to remove selected portions of the recording head and thereby shape the recording head. More specifically, according to this method, the focused particle beam can remove selected portions of the write head without irradiation of the read head.
  • This aspect of the invention thus locates a first structural element with respect to a second structural element in a multi-layer lithographically fabricated device in the following manner.
  • image with a focused particle beam, first marker element and at least one of the second structural element and the second marker element on the multi-layer device.
  • the first structural element is in a first lithographic layer, and the first marker element is in the same first lithographic layer at a known distance and direction from the first structural element.
  • the second structural element is in a second lithographic layer, and the second marker element is in the same second lithographic layer.
  • the structural elements and the marker elements intersect a geometrical surface that extends transversely to the first and second lithographic layers.
  • a second step determine, responsive to the first imaging step, the location of the second structural element relative to the location of the first structural element.
  • This determining step can include the processing of information provided by the imaging step for providing information concerning the location of the marker elements.
  • the second structural element and the second marker element are the same element.
  • the second marker element is located at a known distance and direction relative to the second structural element.
  • the invention provides an apparatus for shaping a pole-tip assembly of a recording head.
  • the apparatus includes a focused particle beam for selectively interacting with the multi-layer device describe above.
  • the apparatus includes a platform for receiving the multi-layer device containing the structure for the recording head with a pole-tip assembly and for disposing the multi-layer device for contact with the focused particle beam.
  • the apparatus includes a system for generating image signals responsive to the interaction of the focused particle beam with the first marker element and at least one of the second structural element and the second marker element on the multi-layer device and for generating, responsive to the image signals, a coordinate signal representative of a position of the second structural element relative to the first structural element and relative to the focused particle beam.
  • the apparatus further includes a processor responsive to the coordinate signal for generating a milling signal representative of an instruction for applying the focused particle beam to a selected portion of the second structural element for milling the selected portion of the second structural element.
  • the focused particle beam system images the first marker element and the second structural element located in the multi-layer device. From the location of the first marker element and the second structural element, derived from the images of these elements, the system determines, without irradiating a sensitive first structural element, which portions of the second structural element require milling so as to produce a desired pole-tip configuration. By producing a desired pole-tip configuration, these methods and apparatus produce an improved recording head capable of higher storage density than prior art techniques.
  • the invention provides apparatus and methods for precisely shaping a pole-tip assembly of a magnetic recording transducer without irradiating a sensitive structure, e.g., a read head in the recording transducer.
  • An apparatus for shaping a pole-tip assembly of a recording transducer with a focused particle beam includes a platform for receiving a multi-layer device including the recording transducer and for disposing the multi-layer device for interaction with the focused particle beam.
  • the multi-layer device has a first layer including a first structural element, a second layer including a second structural element, and a shielding layer including a shielding element.
  • the first and second structural elements can be a read head and a write head, respectively.
  • the shielding element is located between the first structural element and the second structural element.
  • the structural elements and the shielding element intersect a geometrical surface that extends transversely to the first, second, and shielding layers, so that imaging at least a portion of the shielding element, at the geometrical surface, provides information that facilitates imaging the second structural element without imaging the first structural element.
  • the apparatus has an element for scanning the focused particle beam over the geometrical surface at a selected first section that includes at least a portion of the shielding element and that does not include the first structural element.
  • the system can select which section of the multi-layer device surface to image by methods, such as an optical microscope registration technique, that are known in the art.
  • the apparatus has an element for generating a first image signal representative of the portion of the shielding element.
  • the first image signal results from interaction of the focused particle beam with the portion of the shielding element.
  • the apparatus has an element for analyzing the first image signal representative of the portion of the shielding element to determine the location of the portion of the shielding element.
  • the apparatus has an element for directing the focused particle beam, in response to the determined location of the portion of the shielding element, to interact with the second structural element without substantially interacting with the first structural element.
  • the apparatus has an element for generating a second image signal responsive to interaction of the focused particle beam with the second structural element.
  • the apparatus has a processor element, responsive to the second image signal, for generating a milling signal.
  • the milling signal represents an instruction for applying the focused particle beam to a selected portion of the second structural element for milling the selected portion of the second structural element.
  • One version of a method according to the present invention employs a focused particle beam to shape a pole-tip assembly of a recording transducer.
  • the method disposes a multi-layer device on a platform for contact with the particle beam.
  • the multi-layer device forms at least one recording transducer.
  • the multilayer device has a first layer including a first structural element, a second layer including a second structural element, and a shielding layer including a shielding element located between the first structural element and the second structural element.
  • the structural elements and the shielding element intersect a geometrical surface that extends transversely to the first, second, and shielding layers, so that imaging at least a portion of the shielding element, at the geometrical surface, provides information to facilitate imaging the second structural element without imaging the first structural element.
  • the system scans the focused particle beam over the geometrical surface at a selected first section that includes at least a portion of the shielding element and that does not include the first structural element.
  • the system generates a first image signal representative of the portion of the shielding element.
  • the first image signal results from interaction of the focused particle beam with the portion of the shielding element.
  • the system analyzes the first image signal representative of the portion of the shielding element to determine the location of the portion of the shielding element.
  • the system directs, responsive to the determined location of the portion of the shielding element, the focused particle beam to interact with the second structural element without requiring interaction with the first structural element.
  • the system generates a second image signal responsive to interaction of the focused particle beam with the second structural element.
  • the system generates, responsive to the second image signal, a milling signal.
  • the milling signal represents an instruction for applying the focused particle beam to a selected portion of the second structural element for shaping the pole-tip assembly by milling the selected portion of the second structural element.
  • the system provides a charge neutralization element for neutralizing charge on the recording transducer.
  • the scanning of the focused particle beam includes scanning the focused particle beam over the geometrical surface at a selected section that includes the portion of the shielding element closest to the second structural element.
  • the generation of a second image signal includes the generation, responsive to the second image signal, of a coordinate signal.
  • the coordinate signal represents an instruction for applying the focused particle beam to a selected portion of the second structural element for shaping the pole-tip assembly by milling the selected portion of the second structural element.
  • the generation of a coordinate signal includes the detection of an edge of the second structural element and generates an edge signal.
  • the edge signal represents a location of the edge of the second structural element relative to the focused particle beam.
  • the generation of a milling signal includes generating, as a function of the second image signal, a presentation signal.
  • the presentation signal represents a pattern presentation of the second structural element.
  • the generation of a milling signal can further include comparing the presentation signal to a pattern signal representative of a select second structural element topography.
  • the generation of a milling signal can include comparing the presentation signal to a plurality of pattern signals and selecting one of the pattern signals as a function of the comparison.
  • the comparison of the presentation signal to the pattern includes the determination of an etching pattern signal representative of one or more areas to etch from the second structural element to conform the second structural element substantially to the select second structural element topography.
  • the determination of an etching pattern signal includes the determination of a minimum etching-time signal.
  • the etching-time signal represents a minimum length of time to apply a milling pattern in order to conform the second structural element substantially to the select second structural element topography.
  • the determination of an etching pattern signal can further include the determination a minimum etching-area signal.
  • the minimum etching-area signal represents a milling pattern having a minimum area to be removed for conforming the second structural element substantially to the select second structural element topography.
  • the generation of a milling signal can further include the generation of a representative instruction signal for deflecting said particle beam to a desired location.
  • the generation of a milling signal can also include the generation of a representative instruction signal for moving the platform to a desired location.
  • the invention provides apparatus and methods that employ a focused particle beam system to mill a second structural element without irradiating a sensitive first structural element, e.g., a read head, of a recording transducer.
  • the focused particle beam system produces a desired pole-tip configuration.
  • the system produces an improved recording transducer capable of higher storage density than recording transducers made according to prior art techniques.
  • the system uses existing features of a multi-layer device that forms a recording transducer.
  • a focused particle beam for practice of the invention can include an ion beam, electron beam, x-ray beam, optical beam or other similar source of directable radiant energy.
  • Figure 1 is a simplified view of a thin-film magnetic recording head according to the invention disposed above a data track of a magnetic medium;
  • Figure 2 is a cross sectional view, along section 2-2 of Figure 1, showing one embodiment of the thin-film magnetic recording head, disposed above a data track of a magnetic medium;
  • Figures 3(a) and 3(b) are perspective views from above of a lithographically fabricated multi-layer device, which contains part of the recording head of Figure 1, at the completion of a first and second step in the fabrication process, respectively;
  • Figures 4(a) - 4(e) are cross sectional views of the multi-layer device of Figures
  • Figure 5 is a perspective view from above of the multi-layer device of Figure
  • Figure 6 shows the cleaved, multi-layer device of Figure 5 containing a defective write head, seen from the plane of the cleaved surface;
  • Figure 7 is a schematic view of one system for manufacturing the thin-film recording head of Figure 1 according to the invention;
  • Figure 8 is a flow chart illustrating one process according to the invention for manufacturing the thin-film recording head of Figure 1 ;
  • Figure 9 illustrates schematically the sequence of a raster scan of a focused particle beam within the trim outlines of Figure 6;
  • Figure 10(a) shows one embodiment of the recording head of Figure 1 with a desired pole-tip configuration as seen from the plane of the cleaved surface;
  • Figure 10(b) shows another embodiment of the multi-layer device of Figure 3(b) without a second marker element
  • Figure 10(c) illustrates the first two steps in a fours step process of fabricating the thin-film recording head of Figure 2 from the multi-layer device of Figure 10(b);
  • Figure 10(d) illustrates the last two steps in a four step process of fabricating the thin film recording head of Figure 2 from the multi-layer device of Figure 10(b);
  • Figure 10(e) shows a recording transducer in a multi-layer device as seen from the perspective of a magnetic recording medium
  • Figures 10(f), 10(g), and 10(h) show steps in a method, according to one embodiment of the invention, of milling the thin-film magnetic recording transducer of Figure 10(e) using the system of Figure 7;
  • Figures 10(i) and 10(j) depict a write head of a magnetoresistive recording transducer before and after processing by a FIB system of the type depicted in Figure 7;
  • Figure 10(k) is a flow chart illustration of one method according to the invention for manufacturing read/write heads.
  • Figure 1 illustrates an example of one type of thin-film recording head.
  • Figure 1 depicts a hard computer-memory disk 15, a recording head 13, a pole-tip assembly 14, a data track 16, and an extension arm 18.
  • the illustrated recording head 13 is disposed at the distal end of the arm 18 and is located just above the rotating disk 15.
  • the recording head records and reads digital data by generating or detecting magnetization states that form the data track 16 on the disk 15.
  • FIG. 2 shows a cross sectional view of one embodiment of the thin-film recording head 12 of Figure 1, disposed above a data track of a magnetic medium 15.
  • the recording head embodiment shown is a thin-film, merged inductive write head and shielded Magneto-Resistive Head (MRH) structure.
  • the recording head 13 has a pole-tip assembly 14 formed from a pole assembly 17.
  • the pole assembly is attached to a slider 27.
  • a pole-tip assembly is defined for the purposes of this application as the elements of the pole assembly that are in proximity to, and that can functionally interact with, the magnetic medium.
  • the illustrated recording head has a pole-tip assembly 14 including elements 21, 24, 11, and 28. According to the invention, these elements are formed from a multi-layer lithographically fabricated device.
  • the device includes conductive layers containing poles and shields.
  • the poles 21 b and 24b, the shields 24b and 28b and the Magneto-Resistive Stripe (MRS) 11 b are separated, at least at one side.
  • the poles, the shields and the MRS can be separated, at least at one side, by insulating layers 26b, 32b, and 33b.
  • element 24b is both a write pole and a read shield.
  • the recording head as a whole includes a first pole 21b, a second pole/shield 24b, a coil 23, a MRS l ib, and a first shield 28b.
  • the poles, the shields, and the MRS extend into the body of the recording head substantially along a first axis.
  • the first axis is substantially perpendicular to the surface of the pole-tip assembly 14. In the illustrated embodiment, the first axis is marked as the Z axis.
  • a write head typically includes at least three parts: the core, the coil and the gap.
  • the core includes poles 21b and 24b.
  • the coil 23, shown in cross section, is wrapped around the core.
  • the write gap 26 separates the pole- tips 21 and 24 of the pole-tip assembly.
  • the core structure is usually called the yoke.
  • Thin-film heads can be made of thin layers of permalloy (81Ni/19Fe) or AlFeSil ( an aluminum, iron and silicon alloy) in, typically, two to four ⁇ m thicknesses.
  • the coil can be made of copper and the gap can be made of AI2O3.
  • the coil 23 carries the write current, which is typically of magnitude ten to twenty rnA peak.
  • the write current is toggled from one polarity to the other to write digital transitions of the remanent magnetization in the recording medium.
  • the write gap 26 permits the magnetic flux circulating in the core to fringe out and intercept the recording medium. In this way, the read/write head 13 writes digital data into the track 16 ( Figure 1 ), in the form of a magnetic spot.
  • a magnetic spot on a disk 15 provides a magnetic fringe field.
  • the read head e.g. a magneto-resistive (MR) head, responds to the magnetic field resulting in a corresponding electrical signal.
  • MR magneto-resistive
  • the magnetic response can be converted to an electrical signal via the anisotropic magneto-resistive effect.
  • the resulting electrical signal reflects the magnetic state of the spot in the track 16 on the disk 15. In this way, the recording head 13 reads magnetic data written on the disk 15.
  • Figures 3(a) and 3(b) are perspective views from above of one embodiment of a lithographically fabricated multi-layer device, which manufacturers can use to produce the recording head of Figure 1.
  • Figures 3(a) and 3(b) show the multi-layer device at the completion of a first and second step in the fabrication process, respectively.
  • Figure 3(a) shows the multi-layer device after completion of a first patterning step and before completion of a second patterning step.
  • a first structural element 11 and a first marker element 12 are present in the multi-layer device.
  • element 12 need not be a square.
  • the marker element 12 has a similar configuration to the structural element 11.
  • Figure 3(b) shows the multi-layer device after completion of the second patterning step.
  • the multi-layer device is cleaved along a geometrical surface 32 that extends transversely to the layers 21a and 11a.
  • the process of cleaving such a multi-layer device is common in the semiconductor fabrication industry. If necessary, part of the cleaving process can include lapping back the geometrical surface substantially along the first axis to expose the structural and the marker elements.
  • the first axis described above, is substantially perpendicular to the geometrical surface 32. In the embodiment shown in Figure 3A, the first axis is the illustrated Z axis.
  • Figures 4(a) - 4(e) show cross sectional views of the multi-layer device of Figures 3(a) and 3(b). These figures illustrate various stages of one embodiment of a photolithographic technique. Manufacturers can use this technique to produce the structure shown as element 21b of Figure 2.
  • typical lithographic techniques deposit alternating layers of conducting and insulating materials onto a substrate by an evaporation, sputtering, plating or other deposition technique that provides precise control of deposition thickness. Chemical etching, reactive ion etching (RIE), or like process steps shape and form the deposited layers into structures having a desired geometry.
  • the distances between certain structures, e.g. head elements and marker elements, located on the same layer and formed by way of these lithographic techniques can be determined without using a FIB system to image the head elements.
  • Figure 4(a) shows a multi-layer device 31 that provides the seven layers of the recording head of Figure 2.
  • This portion of one embodiment of the fabrication process begins with the application of a layer of photoresist 36a to the surface or top layer 21a of the multi-layer device 31.
  • Figure 4(a) shows the multi-layer device at a particular point in one embodiment of the device's fabrication process.
  • a first patterning step is completed. This first step patterns a first structural element, the read head, 11 , and, at a known distance and direction from the first structural element, a first marker element 12. Both elements exist in a common layer 1 la.
  • Figure 4(b) - 4(d) show only the top two layers of Figure 4(a) because the process shown in these Figures does not alter the bottom six layers.
  • shading shows regions of the photoresist that have been exposed to light.
  • the desired configuration of elements in layer 21a determines where the photoresist is exposed.
  • Photoresist is a polymeric mixture that is deposited as a thin layer, perhaps one ⁇ m thick, upon the multi-layer device. Irradiation with light in the near ultraviolet region of the spectrum modifies the chemical properties of the photoresist, and in "positive" photoresist, makes it more soluble to certain developers.
  • one step frequently employed in microstructure fabrication is the projection of the image of a mask onto the photoresist layer. It becomes possible to remove the exposed region of the photoresist by dissolving it with a suitable developer.
  • a solvent can remove the remaining photoresist, potentially leaving layer 21a with a desired configuration. Importantly, this process can produce defects in elements located in layer 21a. In the example shown, element 21 has at least one defect in that it is too wide.
  • the multi-layer device of Figure 4(a) with a configured layer 21a and the remaining photoresist removed is shown in Figure 4(e).
  • a second patterning step has been completed.
  • This second step forms a second structural element, the write head, 21.
  • forming the second structural element completes the second patterning step.
  • the second patterning step also includes forming a second marker element at a known distance and direction from the second structural element. In the latter embodiment, both elements exist in a common layer 21a.
  • the invention is understood as a lithographic process including the steps of 1) patterning in a first common lithographic layer 1 la, a first structural element 11 (e.g. a read head) and, at a known distance and direction, a first marker element 11a; and 2) patterning in a second common lithographic layer 21a, a second structural element 21 (e.g. a write head) and a second marker element 22.
  • the above patterning steps provide the structural and marker elements so that they intersect a single geometrical surface 32 that extends transversely to the first and second lithographic layers.
  • the geometrical surface is planar.
  • viewing the second structural element and the first marker element and at least one of the second structural element and the second marker element, at the geometrical surface provides information for locating the second structural element relative to the first structural element.
  • the second structural element and the second marker element are the same element.
  • the second marker element is located at a known distance and direction relative to the second structural element.
  • the process includes the further step of providing the marker elements with selected spatial overlap along a second axis that extends transversely to the first and second lithographic layers.
  • the second axis is substantially parallel to the Y axis.
  • the process includes yet a further step of providing the structural elements with selected overlap along an axis substantially parallel to the second axis.
  • Figure 5 is a perspective view of the multi-layer device of Figure 3(b) after cleaving the device to expose the read and write heads and their associated marker elements.
  • Figure 6 shows the cleaved, multi-layer device of Figure 5, as seen from the plane of the cleaved surface (which, in the illustrated embodiment, is substantially the same as the plane of the magnetic medium).
  • a first layer 11a includes a first structural element 11 and, at a known distance (dl) along a third axis, a first marker element 12.
  • the third axis is substantially parallel to the layers and to the geometrical surface 32. In the embodiment shown in Figure 5, the third axis is the X axis.
  • a second layer 21a includes a second structural element 21 and, at a known distance (d2) along the third axis, a second marker element 22.
  • the separation of the marker elements along the third axis is ⁇ d m .
  • the separation of the structural elements along the third axis is ⁇ d s .
  • the multi-layer device illustrated in Figures 5 and 6 contains a write head that is too wide along the illustrated X axis to produce narrow tracks of data. Furthermore, manufacturers desire a specific X axis separation between the centers of the write head 21 and the read head 11. To provide the desired pole-tip configuration, the multi-layer device is inserted into a focused particle beam system according to the invention.
  • Figure 7 shows the focused particle beam system 70 for providing a desired pole- tip configuration and for manufacturing the thin-film recording head of Figure 1.
  • the illustrated system 70 includes an ion column 72, a vacuum chamber 82, an optional reactant material delivery system 94 and user control station 110.
  • the system 70 provides a focused particle beam system that can precisely mill thin-film recording heads, including thin-film recording heads having contoured surfaces.
  • a recording head contained within a multi-layer device is seated within the vacuum chamber 82 and operated on by a particle beam generated by the column 72 to mill the pole-tip assembly of the recording head.
  • Figure 1 shows an example of a recording head 13 that can be seated within chamber 82 and processed by the system 70.
  • a focused ion beam system 70 of this type is commercially available from Micrion Corp. of Peabody, Mass.
  • the ion column 72 includes an ion source 74, an extraction electrode 76, a focusing element 78, deflection elements 79, and a focused ion beam 80.
  • the ion column 72 sits above the vacuum chamber 82, and the vacuum chamber 82 houses a stage 84, a platform 86, a read/write head 90, a secondary particle detector 88 and a charge neutralization element 92.
  • the optional reactant material delivery system 94 includes a reservoir 96, a manometer 100, a motorized valve element 102, and delivery conduit 104.
  • the user control station 110 can include a processor 112, a pattern recognition element 114, a memory element 116, a display element 120, a scan generator element 122, and dwell registers 124.
  • the operation of the ion column 72, charge neutralization element 92, and secondary particle detector 88 are controlled by the control station 110.
  • the depicted control station 110 includes a processor element 112 that has a scan generator element 122 that includes dwell register 124.
  • the processor element 112 couples via a transmission path to a control element 118 coupled to the ion beam column 72.
  • the processor element includes a location processor element 115.
  • the depicted processor element 112 can be a conventional computer processor element that includes a CPU element, a program memory, a data memory, and an input/output device.
  • processor element 112 is a IBM Rise 6000 Workstation operating a Unix operating system. As further depicted by Figure 7, the processor element 112 can connect, via the input/output device to a scan generator element 122.
  • the scan generator element is a circuit card assembly that connects to the processor 112 via the processor input/output device.
  • the circuit card assembly scan generator element 122 depicted in Figure 7 includes a scan memory for storing data representative of a scanning pattern that can be implemented by system 70 for scanning ion beam 80 across the surface of the workpiece 90 to selectively mill, or etch the surface of the workpiece 90.
  • the scan generator board element 122 depicted in Figure 7 can be a conventional computer memory circuit card having sufficient memory for storing digital data information representative of locations of the recording head that are to be processed by the particle beam system 70.
  • a scan generator board suitable for practice with the present invention includes a series of memory locations, each of which corresponds to a location on the recording head surface.
  • Each memory location stores data representative of an X and Y location of the recording head and preferably further has, for each X and Y location, a dwell register for storing digital data representative of a time for maintaining the particle beam on the surface of the recording head at the location represented by the associated X, Y pair.
  • the dwell register provides a memory location for storing a dwell time for applying the focused particle beam to the surface of the recording head, to thereby allow control of the dose delivered to the recording head.”
  • the dose delivered to a location on a workpiece surface can be understood to determine generally the depth to which material is removed from that location of the workpiece.
  • the dwell time signal stored in the dwell register can also be understood as representative of a depth, or Z dimension, for the particle beam milling process. Consequently, the processor 112 that couples to such a scan generator board 122 provides a multi-dimensional milling element for generating milling signals that can control in three dimensions the milling or etching process of the focused particle beam system.
  • the processor 112 employs the X, Y and Z data maintained by the scan generator board 122 to generate milling signals that are transmitted via the transmission path 126 to the control element 118 of the ion column 72.
  • the milling signals provide control element 118 with information for operating the deflector elements 79 to deflect the focused particle beam for scanning or rasterizing the focused particle beam across the surface of the recording head 90, and to maintain the particle beam at the selected location for a specified dwell time to provide milling to a selected depth.
  • the surface of the recording head 90 generally corresponds to a two-dimensional plane that can be defined by an orthogonal pair of -Y and Faxes.
  • a Z axis, that is generally understood as extending parallel to the path of the focused ion beam 80 is also generally orthogonal to the plane defined by the X and Y axis of the surface of the recording head 90.
  • Figure 7 depicts an ion column 72 that includes deflection elements 79 for deflecting an ion beam 80 to scan across the surface of the recording head 90 and thereby direct the focused ion beam to a selected location on the surface of the recording head 90, it will be apparent to one of ordinary skill in the art of focused particle beam processing that any system suitable for directing the focused particle beam to select locations of the recording head surface can be practiced with the invention.
  • the platform 84 can be moved in an X, Y or Z space which corresponds to the X, Y and Z space of the milling process and the milling signals generated by the processor 112 can be provided to a stage control system that moves the stage carrying the recording head 90 to thereby dispose a selected portion of the recording head directly in the path of the focused particle beam to mill the recording head 90.
  • a stage control system that moves the stage carrying the recording head 90 to thereby dispose a selected portion of the recording head directly in the path of the focused particle beam to mill the recording head 90.
  • Other systems and methods for directing the particle beam can be practiced with the present invention without departing from the scope thereof.
  • the depicted scan generator element 122 that is illustrated as a circuit card assembly of read/write computer memory can alternatively be implemented as software program code that runs on a computer platform having an accessible data memory that is configured by the program code to provide storage locations for storing the data representative of the X and Y locations as well as data representative of the dwell time.
  • Such a modification is well within the art of one of ordinary skill and does not depart from the scope of the invention.
  • FIG. 8 is a flow chart illustration of one process according to the invention for manufacturing recording heads using system 70 of Figure 7.
  • one process according to the invention comprises the following steps: Step one 92) pattern a multi-layer lithographically fabricated device with structural and marker elements disposed in the manner described above and illustrated in Figures 3(a) - 4(b); Step two 94) cleave the multi-layer device to expose a geometrical surface that extends transversely to the layers and that substantially contains the structural and marker elements as illustrated in Figures 4(b)-6; Step three 96) generate images of the marker elements of Figure 6 by scanning the ion beam of Figure 7 in the vicinity of the marker elements and by detecting secondary particles emitted as a result of the ion bombardment, and generate, using the location processor 115 of Figure 7, X & Y marker coordinates based on the marker
  • trim outlines 82a and 82b over portions of the write head.
  • Each trim outline 82a and 82b represents a selected portion of the recording head to be removed by a focused particle beam milling process.
  • the trim outlines can have a variety of geometrical shapes including rectangular, square, and polygonal.
  • the trim outlines 82a and 82b identify two etching areas. Within these etching areas a focused particle beam will selectively remove portions of the write head to provide a pole-tip assembly that has a desired configuration.
  • a desired pole-tip configuration can include a specified separation of the read and write heads along the second axis.
  • Figure 9 shows the process of a raster scan of a focused particle beam within the trim outlines of Figure 6.
  • the trim outlines 82a and 82b represent where the focused particle beam will mill the multi-layer device.
  • the processor 112 based on the X & Y marker coordinates, directs the particle beam 80 to mill the surface of the recording head 90 in accordance with the trim outlines. Again, it is important to note that the trim outlines do not have to be rectangular as shown.
  • the trim outlines can have a variety of geometrical shapes.
  • the processor 112 generates a series of milling instructions for operating the ion column 72 to implement a digital raster pattern as depicted in Figure 9.
  • Figure 9 illustrates a digital raster pattern 82 that comprises a series of pixel locations 84 with a corresponding pitch 86.
  • the digital raster pattern shown is a serpentine raster pattern. However, manufacturers can employ a variety of raster patterns including a spiral pattern.
  • the pitch is usually smaller than the beam spot size.
  • a typical beam spot size is between approximately .7 microns and .2 microns.
  • the processor element 112 generates a set of milling instructions which represent the X and Y locations for directing the particle beam 80 to mill the surface of the recording head 90 and remove the portion of the recording head outlined by the trim outlines 82a, 82b.
  • the processor is programmable.
  • Figure 10(a) is a view of one embodiment of the recording head of Figure 1 seen from the plane of the magnetic medium with the pole-tip configuration represented in Figure 6 changed due to focused particle beam milling.
  • the focused particle beam system 70 has selectively removed portions of the write head 21 so as to produce a desired configuration of the recording head and a desired separation of the read and write head along the third axis, illustrated as the X axis.
  • Figure 10(b) is another embodiment of the multi-layer lithographically fabricated device of according to the invention. This multi-layer device is similar to the device of Figure 3b. This multi-layer device is different from the device shown in Figure 3b in that it does not contain a second marker element 22.
  • Figure 10(b) includes a first structural element 11 , a second structural element 21. and a first marker element 21.
  • Figure 10(c) shows the first two steps in a four step process for fabricating the thin-film recording head of Figure 2 using the multi-layer device of Figure 10(b).
  • the focused ion beam system 70 locates the top edge of layer 24a.
  • the system 70 locates the top edge of layer 24a by imaging a vertical section 99 of the multilayer device avoiding the structural and marker elements. For example, the system can image a vertical section on the far left side 99 of the multi-layer device.
  • the system obtains a vertical reference point.
  • the vertical axis is the Y axis.
  • the system can then image a horizontal section 89 of the multi-layer device, the vertical location of the horizontal section being appropriately located to image the second structural element 21, based on the previously determined location of the upper edge of layer 24a. From the horizontal section image, the system 70 obtains the center point of element 21.
  • Figure 10(d) shows the last two steps in a four step process of the fabrication of the thin-film recording head of Figure 2 from the multi-layer device of Figure 10(a).
  • the system 70 images a section 87 avoiding the first structural element 1 1 and locating element 12.
  • the system 70 determines the location of second structural element 21 , places trim outlines 82a, and mills element 21 to produce a desired pole-tip configuration including a correct offset between the structural elements.
  • Figures 10(f), 10(g) and 10(h) illustrate sequential steps for manufacturing a thin-film recording transducer in one version of a method according to the present invention.
  • Figure 10(k) is a flow chart that illustrates one embodiment of the method illustrated in Figures 10(f), 10(g) and 10(h).
  • the method disposes a multi-layer device 310 that forms a recording transducer 13 on a platform 86 for contact with the particle beam 80.
  • the multi-layer device 310 as shown in Figure 10(e), has a first layer 312 including a first structural element 314, a second layer 316 including a second structural element 318, and a shielding layer 320.
  • the shielding layer 320 includes a shielding element 322 located between the first structural element 314 and the second structural element 318.
  • the shielding layer 320 is between the first layer 312 and the second layer 316
  • the shielding element 322 in the shielding layer 320 is between the first structural element 314 and the second structural element 318.
  • the first structural element 314 and the second structural element 318 can be a read pole and a write pole, respectively, of a pole-tip assembly.
  • Geometrical surface 381 that is shown in Figure 10(e) corresponds to surface 32 in Figures 3 A and 3B.
  • the structural elements 314, 318 and the shielding element 322 intersect the geometrical surface 381.
  • the geometrical surface extends transversely to the first, second, and shielding layers 312, 316, 320.
  • imaging at least a portion of the shielding element 322, at the geometrical surface 381, provides information to facilitate imaging the second structural element 318 without requiring irradiation of the first structural element 314.
  • the illustrated method in operation 200 scans the focused particle beam 80 over the geometrical surface 381 at a selected portion that includes at least a first portion of the shielding element 322 and that does not include the first structural element 314.
  • the method in operation 200, generates a first image signal representative of the first portion of the shielding element 322.
  • the first image signal results from interaction of the focused particle beam 80 with the first portion of the shielding element 322.
  • the method in operation 202, analyzes the first image signal of the first portion of the shielding element 322 to determine the location of the first portion of the shielding element 322.
  • the method in operation 204, directs the focused particle beam 80, in response to the determined location of the portion of the shielding element 322, to interact with the second structural element 318 without substantially interacting with the first structural element 314.
  • the method in operation 204, generates a second image signal responsive to interaction of the focused particle beam 80 with the second structural element 318.
  • the method in operation 208, analyzes the second image signal of the second structural element 318 to determine the location and the shape of the second structural element 318.
  • the method in operation 210, generates a milling signal, in response to the location and shape of the second structural element 318.
  • the milling signal represents an instruction for applying the focused particle beam 80 to a selected portion of the second structural element 318 for shaping the pole-tip assembly by milling the selected portion of the recording transducer 90.
  • a cell describes a selected geometric area that the focused particle beam of the system is allowed to scan.
  • a cell can also represent a set of actions, e.g., etching and imaging, that are performed within that selected geometric area.
  • a cell can include the whole field of view (FOV) of the focused particle beam or any subset thereof.
  • Figure 4B shows a FON cell 330 that spans the entire FOV of the focused particle beam.
  • a second cell e.g., cell 332, can be located within the FOV cell 330. Further, a second cell can be placed on top of, or adjacent to, a first cell.
  • a cell can be static or dynamic.
  • a dynamic cell has the property that the shape, location, or function of the cell can be determined by a feature or structure found in, or action performed in, another cell.
  • the process according to the invention wherein the shape and the function of a cell are set dynamically is termed dynamic selective imaging.
  • dynamic selective imaging is when a focused particle beam system according to the invention images a first section of a FOV and selects, based on what features or structures are found in the first section, a second section of the FOV to image.
  • a cell can be placed by a control system.
  • a control system assists in creating a cell by controlling the electrostatic deflection of the focused ion beam.
  • the specified control system causes the beam to impinge on that section of the substrate surface which constitutes the desired cell.
  • a linguistic or abstract description of a typical structure of interest is termed a model.
  • a system according to the invention can search in a cell for features that correspond to one or more models. Different characteristics of a feature, such as the size and shape of the feature, can be used to match a feature found in a cell to a model.
  • the system searches for the edges of a feature located within a particular cell.
  • the system detects , among other things, the contrast between a feature and the background.
  • the marker element has a fixed spatial relationship to the first structural element.
  • a focused particle beam system can determine the relative location of the first and second structural elements. Consequently, the focused particle beam system can determine, without irradiating the sensitive first structural element of a wafer with a marker element, which portions of the second structural element require milling.
  • a system that can determine which portions of a second structural element require milling, without irradiating a sensitive first structural element of a multi-layer device containing a recording transducer, e.g., a wafer, when the multilayer device does not include the marker element described above.
  • the focused ion beam system 70 performs the following steps. 1) The system moves the ion column 72 so that the FOV consists of FOV cell 330 having a predetermined size, e.g. 10 microns by 10 microns. 2) The system 70 images a shielding element search cell 332 which is located within FOV cell 330.
  • the system selects a first section of the geometrical surface 381 that does not include the first structural element 314.
  • the system images a vertical section on the far left side of the multi-layer device shown in Figure 10(f).
  • the system searches for a feature that matches a model 350, e.g., a shielding element
  • the system Upon matching the feature to the model, the system locates the top edge 322b of the shielding element 322 within cell 332. 4) If a feature matching model 350 is not located, the system moves the cell 332 systematically, still avoiding irradiating the first structural element 314, and repeats steps 2 and 3 until the top edge 322b of shielding element 322 is located. 5) The system then places a second structural element search cell 334 above the shielding element 322, on the side of the shielding element opposite the first structural element 314. 6) The system images cell 334. 7) The system searches for model 352, e.g. a write pole model.
  • model 352 e.g. a write pole model.
  • the system moves cell 334 systematically, still avoiding irradiating the first structural element 314, and repeats steps 7 and 8 until model 352 is found. 9)
  • the system attaches trim boxes 340 and 342 to the second structural element 318, based, in part, on the image of the second structural element 318 in cell 334.
  • the focused ion beam system 70 performs selective imaging according to the following steps. 1) The system moves to cell 330, without imaging cell 330. 2) The system 70 images cell 332, which is located within cell 330, a selected distance from the first structural element.
  • Cell 332 can be a tall, thin cell located in the periphery of cell 330, spanning the entire height of cell 330. 3)
  • the system searches for model 350, a shielding element. Upon matching the feature to the model, the system locates the top edge 322b of the shielding element 122 within cell 332. 4) If a feature matching model 350 is not located, the system moves cell 332 systematically, still avoiding irradiating the first structural element 314, and repeats steps 2 and 3 until the top edge 322b of shielding element 322 is found. 5)
  • the system 70 images cell 336, which is located within FOV cell 330, a selected distance from the first structural element 314.
  • Cell 336 can be a tall, thin cell located in the periphery of cell 330, opposite cell 332, spanning the entire height of cell 330. 6)
  • the system searches for a feature that matches model 350, e.g. a shielding element. Upon matching the feature to the model, the system locates the top edge 322b of the shielding element 322 within cell 336. 7) If a feature matching model 350 is not located, the system moves cell 332 systematically, still avoiding irradiating the first structural element, and repeats steps 5 and 6 until the top edge 322b of shielding element 322 is found. 8) The system places cell 334 above the shielding element 322, on the side of the shielding element opposite the first structural element 314. 9) The system images cell 334.
  • model 350 e.g. a shielding element.
  • the system searches for a feature that matches model 352, e.g., a write pole model.
  • a feature matching model 352 is not found, the system moves cell 334 systematically, still avoiding irradiating the first structural element 314, and repeats steps 9 and 10 until a second structural element is found.
  • the system attaches trim boxes 340 and 342 to the second structural element 318 based, in part, on the image of the second structural element 318.
  • the processor 112 includes a trim outline element that employs the geometric pattern information of the write head to generate a geometric pattern or trim outline that represents a selected portion of the write head that is to be milled.
  • the processor 112 generates from this trim outline a series of milling instructions that are transmitted via transmission path 126 to the control element 118 of the ion column 72.
  • the milling instructions can include deflection signals that cause the deflection elements 79 to scan across the surface of the recording transducer 90 according to the geometric pattern determined by the processor 112. In this way, the processor 112 generates milling instructions that direct the ion beam 80 to etch away a selected portion of the recording transducer 90.
  • the processor element 112 can find features that vary in size and position.
  • the processor element 112 can apply a trim outline to the actual features found.
  • the placement and size of the trim outline is determined by "pinning" edges of the template to edges of the outline that the pattern recognition element has found.
  • the processor's pinning operation can be understood as a logical attachment of a trim outline edge to the outline of the feature that the pattern recognition element has found. This attachment will allow the trim outline to correspond to a particular feature. Pins can cause a trim outline to "shrink wrap" around a portion of the detected feature.
  • the system can apply constraints.
  • a constraint is a required fixed dimension between two trim outlines.
  • a constraint overrides any pin actions.
  • a milling pattern made up of adaptable trim outlines can adapt to produce a desired read/write head configuration. In other words, by using pins and constraints, similar patterns or features can be milled from features of varying configurations.
  • the system 70 depicted in Figure 1 provides a system for manufacturing thin-film magnetic read/write heads that automatically identifies the location and geometry of a second structural element, and generates, from the location and geometry, a set of milling signals that direct the focused particle beam to mill the recording transducer and thereby form a pole-tip assembly that has the precise geometry suitable for generating a selected magnetic field pattern.
  • One such operation is illustrated in Figures 10(f), 10(g), and 10(h).
  • a registration post is disposed sufficiently far from the pole-tip assembly of the recording transducer that a first image is taken with sufficiently low magnification as to generate an image that encompasses both the registration post and a portion of the read/write head.
  • the pattern recognition element 114 generates a second image that represents, at a higher magnification, the pole-tip assembly 14 of the read/write head. At such a high magnification, the registration post does not appear within the borders of the image.
  • the pattern recognition element 114 passes the geometric pattern information depicted in Figure 10(g) to the processor element 112.
  • the processor element 112 generates a trim outline signal, depicted in Figure 10(h), that includes a first trim outline 340 and a second trim outline 342, each of which represents geometric patterns superimposed over the image of the pole-tip assembly 14.
  • Each trim outline 340 and 342 further represents a selected portion of the recording transducer to be removed by the ion milling process.
  • the trim outlines 340 and 342 of Figure 10(h) identify two etching areas that will selectively remove portions of the second structural element.
  • the processor 112 generates from the trim outline signals 340 and 342 a set of milling instructions for directing the particle beam 80 to mill the surface of the recording transducer 90.
  • the processor 112 generates a series of milling instructions for operating the ion column 72 to implement a digital raster pattern as depicted in Figure 9.
  • Figure 9 illustrates a digital raster pattern 82a that comprises a series of pixel locations 82, each corresponding to the spot size of the ion beam 80, and separated by a pitch 86 which in the depicted digital raster pattern 82 is similarly sized to the beam spot size, and preferably small enough to allow for overlap during the milling process.
  • One such beam spot size is approximately .7 microns.
  • the processor element 112 therefore generates from the trim outline 340 a set of milling instructions which represent the X and Y locations for directing the particle beam 80 to mill the surface of the recording transducer 90 and remove the portion of the recording transducer outlined by the trim outline signal 340.
  • Figures 10(i) and 10(j) depict a magnetoresistive transducer before and after being milled by a system according to the invention to selectively remove portions of the recording transducer surface.
  • the focused particle beam has removed two rectangular portions from either side of the write head and part of the upper shield to reduce the track width.
  • ESD electrostatic discharge
  • Each milled portion depicted in Figure 10(j) corresponds to the depicted trim outlines 340 and 342 depicted in Figure 10(h).
  • the milling signals generated by the processor 112 direct the particle beam 80 to mill the workpiece to substantially the same depth over the entire portion of the trim outline. Accordingly, the write pole has an upper surface and a recessed lower surface.
  • the invention provides improved systems and methods for forming thin film recording transducers and for employing a focused particle beam to manufacture thin-film recording transducers. It will be appreciated by those skilled in the art of thin film recording manufacturing techniques that changes can be made to the embodiments and processes described above without departing from the broad inventive concept thereof. It will further be understood therefore, that the invention is not to be limited to the particular embodiments disclosed herein but is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

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Abstract

This invention relates to a multi-layer lithographically fabricated device (31a) used to produce improved thin-film recording transducers. It further relates to a focused particle beam system for milling a recording transducer pole-tip assembly without irradiating a sensitive structure, e.g. a read head, of the recording transducer. The invention precisely forms a pole-tip assembly by milling a second structural element (21) without irradiating a first structural element (11). The invention avoids irradiating the first structural element by placing a first marker element (12), which can be imaged and/or damaged, in the same layer of a multi-layer lithographically fabricated device as the first structural element. The marker element has a fixed spatial relationship to the first structural element. Thus, by imaging the first marker element and the second structural element, and knowing the separation (dl) between the first structural element and the first marker element, a focused particle beam system (70) can determine the relative location of the first and second structural elements. Alternatively, a system according to the invention employs a shielding element (322) and selective imaging to avoid irradiating a sensitive first structural element, such as a read head, of a recording transducer. Consequently, the focused particle beam system can determine, without irradiating the sensitive first structural element, which portions of the second structural element require milling. In this manner, the focused particle beam system mills the second structural element to produce a desired pole-tip configuration (21). By producing a desired pole-tip configuration, these methods and apparatus produce an improved recording transducer capable of producing higher storage density than recording transducers made with prior art techniques.

Description

THIN-FILM MAGNETIC RECORDING HEAD MANUFACTURE
Background
This invention relates to apparatus and methods for manufacturing improved thin-film magnetic recording transducers, commonly referred to as recording transducers. More specifically, it relates to a focused particle beam system for milling a portion of a pole-tip assembly of the recording transducer without irradiating a sensitive structure, e.g. a read head, of the recording transducer.
Thin-film magnetic recording transducers have gained wide acceptance in the data storage industry. A recording transducer includes a write head and a read head. The recording transducer has an air bearing surface that passes adjacent to a recording medium, such as a magnetic disk. The portions of the recording transducer, including portions of the write head and of the read head, that are proximate to the air bearing surface form a small, precisely shaped pole-tip assembly. The size and shape of the pole-tip assembly, which include features on the order of one-half a micron, in part determine the magnetic field pattern produced by the recording transducer. This magnetic field pattern effects how narrowly the recording transducer can record data tracks on the magnetic media of magnetic memory storage devices, such as computer hard disks, and digital data tape drives. Thinner data tracks allow a storage device to store more data tracks per area of media and therefore more data per device. Accordingly, precisely forming the pole-tip assembly of the recording transducer results in an increase in the total data storage capacity of a magnetic memory device. Manufacturers seek to form the geometry of a pole-tip assembly with high precision, and consequently achieve pole-tip assemblies capable of providing magnetic field patterns suitable for writing narrow tracks of recorded data.
Manufacturers presently fabricate multiple recording transducers from a single multi-layer device, and endeavor to form the precise desired shape of the pole-tip assembly of a recording transducer by employing lithographic techniques in fabricating the multi-layer device. Typically, lithographic techniques deposit alternating layers of conductive and insulating materials onto a substrate by an evaporation, sputtering, plating, or other deposition technique that provides precise control of the deposition thicknesses. Chemical etching, reactive ion etching (RIE), or other techniques shape and form the deposited layers into a pole-tip assembly having the desired geometry. Thus, a multi-layer lithographicaly fabricated device can form a plurality of recording transducers having pole-tip assemblies. Although existing lithographic techniques work sufficiently well to provide pole- tip assemblies having feature sizes suitable for current data storage capacity, these lithographic techniques are limited as to the small feature sizes that they can produce. For example, present photolithographic techniques require precise application of photoresist layers. Commonly, the photoresist layer is applied to produce a topology that includes voids having aspect ratios of 10: 1 or larger. Such topologies are difficult to achieve reliably, at the desired small sizes, using such a photoresist technique.
Thus, these lithographic techniques are poorly suited for achieving a high yield of precisely formed, ultra-small, pole-tip assemblies. In the interest of increased storage density, manufacturers decrease the dimensions of a desired pole-tip assembly. As the dimensions of the desired pole-tip assembly decrease, manufacturers who use existing lithographic techniques experience yield loss. In other words, even if manufacturers using existing lithographic techniques are successful in achieving a desired pole-tip assembly configuration, they generally achieve that desired configuration with a low yield.
The kinds of defects that occur during the manufacturing process are difficult to predict and vary widely. Accordingly, the application of a universal photoresist pattern to the surface of a pole-tip assembly is a generalized solution that often is ill suited to the actual manufacturing defect of any one recording transducer. Therefore, current techniques for producing a magnetic recording transducer have several serious limitations with respect to control of pole-tip assembly geometry.
Consequently, higher density data storage devices can require micromachining of the recording transducer used with the devices. Manufacturers can micromachine the recording transducer while it is contained in a multi-layer device. Prior to micromachining, a multi-layer device is lithographically fabricated. Once the multilayer device is fabricated, it is cleaved at a selected location and the cleaved surface is polished to expose at least one recording transducer pole-tip assembly formed by the multi-layer device.
The micromachining of a recording transducer can require accurate shaping of a write head. However, the read head can employ a sensitive structure such as a Magneto- Resistive Stripe (MRS). A MRS can suffer damage as a result of irradiation by a focused ion beam (FIB). For background information on the design and function of a MRS and an inductive write head, see the text "Magneto-Resistive Heads, Fundamentals and Applications" by John C. Mallinson (Academic Press, Inc., San Diego 1996), incorporated herein by reference. It is important to note that the MRS and the write head can each have sublayers. An MRS can include thin-film sublayers, each five to six angstroms thick. The properties of a read head, including a MRS, can be altered during irradiation by a focused ion beam (FIB). Thus, there is a need for focused ion beam systems and methods that locate and accurately shape a write head without irradiating a read head of a pole-tip assembly of a thin-film magnetic recording transducer.
Accordingly, it is an object of the present invention to provide apparatus and methods for manufacturing improved thin-film magnetic recording transducers using a focused particle beam.
It is a further object of the present invention to precisely form the pole-tip assembly of a magnetic recording transducer without irradiating a sensitive structure, e.g., a read head, in the recording transducer. It is a further object of the present invention to provide a multi-layer lithographically fabricated device for manufacturing improved thin-film recording transducers.
It is a further object of the present invention to provide a lithographic process for fabricating a multi-layer device for manufacturing improved thin-film recording heads. Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention is described herein in connection with certain embodiments; however, it will be clear to those skilled in the art of magnetic recording transducer manufacture that various modifications, additions and subtractions can be made to the described embodiments without departing from the spirit or scope of the invention.
Summary of the Invention
One embodiment of the invention precisely forms a pole-tip assembly by milling a second structural element without irradiating a first structural element. The invention avoids irradiating the first structural element by placing a first marker element, which can be imaged and/or damaged, in the same layer of a multi-layer lithographically fabricated device as the first structural element. The marker element has a fixed spatial relationship to the first structural element. Thus, by imaging the first marker element and the second structural element, and knowing the separation between the first structural element and the first marker element, a focused particle beam system can determine the relative location of the first and second structural elements. Consequently, the focused particle beam system can determine, without irradiating the sensitive first structural element, which portions of the second structural element require milling. In this manner, the focused particle beam system mills the second structural element to produce a desired pole-tip configuration. By producing a desired pole-tip configuration, these methods and apparatus produce an improved recording head capable of higher storage density than prior art techniques. Thus, the invention provides lithographic methods and apparatus for manufacturing improved thin-film recording heads. Furthermore, the invention provides methods and apparatus for employing a focused particle beam to mill a recording head pole-tip assembly without irradiating a sensitive structure, e.g. a read head, of the pole- tip assembly. A focused particle beam for practice of the invention can include an ion beam, electron beam, x-ray beam, optical beam or other similar source of directable radiant energy.
One embodiment of the lithographic method includes the following steps: i) pattern, in a common first lithographic layer, a first structural element and, at a known distance and direction, a first marker element; and ii) pattern, in a common second lithographic layer, a second structural element and a second marker element. The above patterning steps provide the structural elements and the marker elements in a spatial arrangement such that they intersect a geometrical surface that extends transversely to the first and second lithographic layers. Consequently, viewing the first marker element and at least one of the second structural element or the second marker element, at the geometrical surface, provides information for locating the second structural element relative to the first structural element. In one embodiment, the second structural element and the second marker element are the same element. In another embodiment, the second marker element is located at a known distance and direction relative to the second structural element.
One embodiment of the process described above provides a multi-layer lithographically fabricated device including a first and second layer. The first layer has a first structural element, and, at a known distance and direction relative thereto, a first marker element. The second layer has a second structural element, and, a second marker element. The structural and marker elements intersect a geometrical surface that extends transversely to the first and second layers so that viewing the first marker element and at least one of the second structural element and the second marker element, at the geometrical surface, provides information for locating the second structural element relative to the first structural element. As stated above, in one embodiment, the second structural element and the second marker element are the same element. In another embodiment, the second marker element is located at a known distance and direction relative to the second structural element.
According to another aspect of the invention, subsequent to the lithographic fabrication of the multi-layer device, manufacturers cleave the device along the above mentioned geometrical surface. Cleaving the device along the geometrical surface exposes the structural and marker elements. According to another aspect, the invention provides methods and apparatus for employing a focused particle beam system to image marker elements on a multi-layer lithographically fabricated device containing the structure for a magnetic recording head. These processes further employ a processor to generate milling signals based on the physical location of the marker elements as determined from an imaging step. Those signals direct a focused particle beam to remove selected portions of the recording head and thereby shape the recording head. More specifically, according to this method, the focused particle beam can remove selected portions of the write head without irradiation of the read head. This aspect of the invention thus locates a first structural element with respect to a second structural element in a multi-layer lithographically fabricated device in the following manner. In a first step, image, with a focused particle beam, first marker element and at least one of the second structural element and the second marker element on the multi-layer device. The first structural element is in a first lithographic layer, and the first marker element is in the same first lithographic layer at a known distance and direction from the first structural element. The second structural element is in a second lithographic layer, and the second marker element is in the same second lithographic layer. The structural elements and the marker elements intersect a geometrical surface that extends transversely to the first and second lithographic layers. In a second step, determine, responsive to the first imaging step, the location of the second structural element relative to the location of the first structural element. This determining step can include the processing of information provided by the imaging step for providing information concerning the location of the marker elements. As stated above, in one embodiment, the second structural element and the second marker element are the same element. In another embodiment, the second marker element is located at a known distance and direction relative to the second structural element.
According to yet another aspect, the invention provides an apparatus for shaping a pole-tip assembly of a recording head. The apparatus includes a focused particle beam for selectively interacting with the multi-layer device describe above. The apparatus includes a platform for receiving the multi-layer device containing the structure for the recording head with a pole-tip assembly and for disposing the multi-layer device for contact with the focused particle beam. The apparatus includes a system for generating image signals responsive to the interaction of the focused particle beam with the first marker element and at least one of the second structural element and the second marker element on the multi-layer device and for generating, responsive to the image signals, a coordinate signal representative of a position of the second structural element relative to the first structural element and relative to the focused particle beam. The apparatus further includes a processor responsive to the coordinate signal for generating a milling signal representative of an instruction for applying the focused particle beam to a selected portion of the second structural element for milling the selected portion of the second structural element. Thus, according to a preferred embodiment of the invention described above, the focused particle beam system images the first marker element and the second structural element located in the multi-layer device. From the location of the first marker element and the second structural element, derived from the images of these elements, the system determines, without irradiating a sensitive first structural element, which portions of the second structural element require milling so as to produce a desired pole-tip configuration. By producing a desired pole-tip configuration, these methods and apparatus produce an improved recording head capable of higher storage density than prior art techniques.
According to another aspect, the invention provides apparatus and methods for precisely shaping a pole-tip assembly of a magnetic recording transducer without irradiating a sensitive structure, e.g., a read head in the recording transducer. An apparatus for shaping a pole-tip assembly of a recording transducer with a focused particle beam, according to one embodiment of the invention, includes a platform for receiving a multi-layer device including the recording transducer and for disposing the multi-layer device for interaction with the focused particle beam. The multi-layer device has a first layer including a first structural element, a second layer including a second structural element, and a shielding layer including a shielding element. The first and second structural elements can be a read head and a write head, respectively. The shielding element is located between the first structural element and the second structural element. The structural elements and the shielding element intersect a geometrical surface that extends transversely to the first, second, and shielding layers, so that imaging at least a portion of the shielding element, at the geometrical surface, provides information that facilitates imaging the second structural element without imaging the first structural element. The apparatus has an element for scanning the focused particle beam over the geometrical surface at a selected first section that includes at least a portion of the shielding element and that does not include the first structural element. The system can select which section of the multi-layer device surface to image by methods, such as an optical microscope registration technique, that are known in the art. The apparatus has an element for generating a first image signal representative of the portion of the shielding element. The first image signal results from interaction of the focused particle beam with the portion of the shielding element. The apparatus has an element for analyzing the first image signal representative of the portion of the shielding element to determine the location of the portion of the shielding element.
The apparatus has an element for directing the focused particle beam, in response to the determined location of the portion of the shielding element, to interact with the second structural element without substantially interacting with the first structural element. The apparatus has an element for generating a second image signal responsive to interaction of the focused particle beam with the second structural element. In addition, the apparatus has a processor element, responsive to the second image signal, for generating a milling signal. The milling signal represents an instruction for applying the focused particle beam to a selected portion of the second structural element for milling the selected portion of the second structural element.
One version of a method according to the present invention employs a focused particle beam to shape a pole-tip assembly of a recording transducer. The method disposes a multi-layer device on a platform for contact with the particle beam. The multi-layer device forms at least one recording transducer. As noted above, the multilayer device has a first layer including a first structural element, a second layer including a second structural element, and a shielding layer including a shielding element located between the first structural element and the second structural element. The structural elements and the shielding element intersect a geometrical surface that extends transversely to the first, second, and shielding layers, so that imaging at least a portion of the shielding element, at the geometrical surface, provides information to facilitate imaging the second structural element without imaging the first structural element.
The system scans the focused particle beam over the geometrical surface at a selected first section that includes at least a portion of the shielding element and that does not include the first structural element. The system generates a first image signal representative of the portion of the shielding element. The first image signal results from interaction of the focused particle beam with the portion of the shielding element. The system analyzes the first image signal representative of the portion of the shielding element to determine the location of the portion of the shielding element. The system directs, responsive to the determined location of the portion of the shielding element, the focused particle beam to interact with the second structural element without requiring interaction with the first structural element. The system generates a second image signal responsive to interaction of the focused particle beam with the second structural element. Then, the system generates, responsive to the second image signal, a milling signal. The milling signal represents an instruction for applying the focused particle beam to a selected portion of the second structural element for shaping the pole-tip assembly by milling the selected portion of the second structural element.
According to further features of the invention, the system provides a charge neutralization element for neutralizing charge on the recording transducer. The scanning of the focused particle beam includes scanning the focused particle beam over the geometrical surface at a selected section that includes the portion of the shielding element closest to the second structural element.
The generation of a second image signal includes the generation, responsive to the second image signal, of a coordinate signal. The coordinate signal represents an instruction for applying the focused particle beam to a selected portion of the second structural element for shaping the pole-tip assembly by milling the selected portion of the second structural element.
The generation of a coordinate signal includes the detection of an edge of the second structural element and generates an edge signal. The edge signal represents a location of the edge of the second structural element relative to the focused particle beam.
The generation of a milling signal includes generating, as a function of the second image signal, a presentation signal. The presentation signal represents a pattern presentation of the second structural element. The generation of a milling signal can further include comparing the presentation signal to a pattern signal representative of a select second structural element topography. The generation of a milling signal can include comparing the presentation signal to a plurality of pattern signals and selecting one of the pattern signals as a function of the comparison.
The comparison of the presentation signal to the pattern includes the determination of an etching pattern signal representative of one or more areas to etch from the second structural element to conform the second structural element substantially to the select second structural element topography.
The determination of an etching pattern signal includes the determination of a minimum etching-time signal. The etching-time signal represents a minimum length of time to apply a milling pattern in order to conform the second structural element substantially to the select second structural element topography. The determination of an etching pattern signal can further include the determination a minimum etching-area signal. The minimum etching-area signal represents a milling pattern having a minimum area to be removed for conforming the second structural element substantially to the select second structural element topography.
The generation of a milling signal can further include the generation of a representative instruction signal for deflecting said particle beam to a desired location. The generation of a milling signal can also include the generation of a representative instruction signal for moving the platform to a desired location.
Thus, the invention provides apparatus and methods that employ a focused particle beam system to mill a second structural element without irradiating a sensitive first structural element, e.g., a read head, of a recording transducer. In this manner, the focused particle beam system produces a desired pole-tip configuration. By producing a desired pole-tip configuration, the system produces an improved recording transducer capable of higher storage density than recording transducers made according to prior art techniques. Further, the system uses existing features of a multi-layer device that forms a recording transducer. A focused particle beam for practice of the invention can include an ion beam, electron beam, x-ray beam, optical beam or other similar source of directable radiant energy.
These and other aspects of the invention are evident in the drawings and in the description which follows.
Brief Description of the Drawings
The foregoing and other objects, features and advantages of the invention will be apparent from the following description and apparent from the accompanying drawings, in which like reference characters refer to the same parts throughout the different views. Figure 1 is a simplified view of a thin-film magnetic recording head according to the invention disposed above a data track of a magnetic medium;
Figure 2 is a cross sectional view, along section 2-2 of Figure 1, showing one embodiment of the thin-film magnetic recording head, disposed above a data track of a magnetic medium; Figures 3(a) and 3(b) are perspective views from above of a lithographically fabricated multi-layer device, which contains part of the recording head of Figure 1, at the completion of a first and second step in the fabrication process, respectively;
Figures 4(a) - 4(e) are cross sectional views of the multi-layer device of Figures
3(a) and 3(b) at various stages in one embodiment of the fabrication process; Figure 5 is a perspective view from above of the multi-layer device of Figure
3(b) after cleaving the device to expose the read and write heads and their associated marker elements;
Figure 6 shows the cleaved, multi-layer device of Figure 5 containing a defective write head, seen from the plane of the cleaved surface; Figure 7 is a schematic view of one system for manufacturing the thin-film recording head of Figure 1 according to the invention; Figure 8 is a flow chart illustrating one process according to the invention for manufacturing the thin-film recording head of Figure 1 ;
Figure 9 illustrates schematically the sequence of a raster scan of a focused particle beam within the trim outlines of Figure 6; Figure 10(a) shows one embodiment of the recording head of Figure 1 with a desired pole-tip configuration as seen from the plane of the cleaved surface;
Figure 10(b) shows another embodiment of the multi-layer device of Figure 3(b) without a second marker element;
Figure 10(c) illustrates the first two steps in a fours step process of fabricating the thin-film recording head of Figure 2 from the multi-layer device of Figure 10(b);
Figure 10(d) illustrates the last two steps in a four step process of fabricating the thin film recording head of Figure 2 from the multi-layer device of Figure 10(b);
Figure 10(e) shows a recording transducer in a multi-layer device as seen from the perspective of a magnetic recording medium; Figures 10(f), 10(g), and 10(h) show steps in a method, according to one embodiment of the invention, of milling the thin-film magnetic recording transducer of Figure 10(e) using the system of Figure 7;
Figures 10(i) and 10(j) depict a write head of a magnetoresistive recording transducer before and after processing by a FIB system of the type depicted in Figure 7; and
Figure 10(k) is a flow chart illustration of one method according to the invention for manufacturing read/write heads.
Description of Illustrated Embodiments The invention provides lithographic fabrication methods and lithographically fabricated devices for manufacturing improved thin-film recording heads. The invention further provides improved methods and apparatus for employing a focused particle beam to manufacture improved thin-film magnetic heads. The invention is understood from the following detailed description of certain exemplary embodiments. Figure 1 illustrates an example of one type of thin-film recording head. Figure 1 depicts a hard computer-memory disk 15, a recording head 13, a pole-tip assembly 14, a data track 16, and an extension arm 18. The illustrated recording head 13 is disposed at the distal end of the arm 18 and is located just above the rotating disk 15. The recording head records and reads digital data by generating or detecting magnetization states that form the data track 16 on the disk 15.
Figure 2 shows a cross sectional view of one embodiment of the thin-film recording head 12 of Figure 1, disposed above a data track of a magnetic medium 15. With reference to Figure 2, the recording head embodiment shown is a thin-film, merged inductive write head and shielded Magneto-Resistive Head (MRH) structure. The recording head 13 has a pole-tip assembly 14 formed from a pole assembly 17. The pole assembly is attached to a slider 27. A pole-tip assembly is defined for the purposes of this application as the elements of the pole assembly that are in proximity to, and that can functionally interact with, the magnetic medium. The illustrated recording head has a pole-tip assembly 14 including elements 21, 24, 11, and 28. According to the invention, these elements are formed from a multi-layer lithographically fabricated device. The device includes conductive layers containing poles and shields. The poles 21 b and 24b, the shields 24b and 28b and the Magneto-Resistive Stripe (MRS) 11 b are separated, at least at one side. The poles, the shields and the MRS can be separated, at least at one side, by insulating layers 26b, 32b, and 33b. Note that element 24b is both a write pole and a read shield. The recording head as a whole includes a first pole 21b, a second pole/shield 24b, a coil 23, a MRS l ib, and a first shield 28b. The poles, the shields, and the MRS extend into the body of the recording head substantially along a first axis. The first axis is substantially perpendicular to the surface of the pole-tip assembly 14. In the illustrated embodiment, the first axis is marked as the Z axis.
A write head typically includes at least three parts: the core, the coil and the gap. In the example shown in Figure 2, the core includes poles 21b and 24b. The coil 23, shown in cross section, is wrapped around the core. The write gap 26 separates the pole- tips 21 and 24 of the pole-tip assembly. In thin-film heads, the core structure is usually called the yoke. Thin-film heads can be made of thin layers of permalloy (81Ni/19Fe) or AlFeSil ( an aluminum, iron and silicon alloy) in, typically, two to four μm thicknesses. The coil can be made of copper and the gap can be made of AI2O3. The coil 23 carries the write current, which is typically of magnitude ten to twenty rnA peak. The write current is toggled from one polarity to the other to write digital transitions of the remanent magnetization in the recording medium. The write gap 26 permits the magnetic flux circulating in the core to fringe out and intercept the recording medium. In this way, the read/write head 13 writes digital data into the track 16 (Figure 1 ), in the form of a magnetic spot.
Similarly, a magnetic spot on a disk 15 provides a magnetic fringe field. As the read/write head passes proximate to a particular magnetic spot, the head enters the fringe field of the spot. The read head, e.g. a magneto-resistive (MR) head, responds to the magnetic field resulting in a corresponding electrical signal. In the case of a MR head, the magnetic response can be converted to an electrical signal via the anisotropic magneto-resistive effect. The resulting electrical signal reflects the magnetic state of the spot in the track 16 on the disk 15. In this way, the recording head 13 reads magnetic data written on the disk 15.
Manufacturers can construct thin-film recording heads from lithographically fabricated multi-layer devices. Figures 3(a) and 3(b) are perspective views from above of one embodiment of a lithographically fabricated multi-layer device, which manufacturers can use to produce the recording head of Figure 1. Figures 3(a) and 3(b) show the multi-layer device at the completion of a first and second step in the fabrication process, respectively. Figure 3(a) shows the multi-layer device after completion of a first patterning step and before completion of a second patterning step. A first structural element 11 and a first marker element 12 are present in the multi-layer device.
Importantly, element 12 need not be a square. In one preferred embodiment the marker element 12 has a similar configuration to the structural element 11. Figure 3(b) shows the multi-layer device after completion of the second patterning step.
Subsequent to completion of the second patterning step, the multi-layer device is cleaved along a geometrical surface 32 that extends transversely to the layers 21a and 11a. The process of cleaving such a multi-layer device is common in the semiconductor fabrication industry. If necessary, part of the cleaving process can include lapping back the geometrical surface substantially along the first axis to expose the structural and the marker elements. The first axis, described above, is substantially perpendicular to the geometrical surface 32. In the embodiment shown in Figure 3A, the first axis is the illustrated Z axis.
Figures 4(a) - 4(e) show cross sectional views of the multi-layer device of Figures 3(a) and 3(b). These figures illustrate various stages of one embodiment of a photolithographic technique. Manufacturers can use this technique to produce the structure shown as element 21b of Figure 2. As noted above, typical lithographic techniques deposit alternating layers of conducting and insulating materials onto a substrate by an evaporation, sputtering, plating or other deposition technique that provides precise control of deposition thickness. Chemical etching, reactive ion etching (RIE), or like process steps shape and form the deposited layers into structures having a desired geometry. Importantly, in accord with the invention, the distances between certain structures, e.g. head elements and marker elements, located on the same layer and formed by way of these lithographic techniques, can be determined without using a FIB system to image the head elements.
Figure 4(a) shows a multi-layer device 31 that provides the seven layers of the recording head of Figure 2. This portion of one embodiment of the fabrication process begins with the application of a layer of photoresist 36a to the surface or top layer 21a of the multi-layer device 31. Thus, Figure 4(a) shows the multi-layer device at a particular point in one embodiment of the device's fabrication process. At the point in the fabrication process shown in Figure 4(a), a first patterning step is completed. This first step patterns a first structural element, the read head, 11 , and, at a known distance and direction from the first structural element, a first marker element 12. Both elements exist in a common layer 1 la.
Figure 4(b) - 4(d) show only the top two layers of Figure 4(a) because the process shown in these Figures does not alter the bottom six layers. In Figure 4(b) shading shows regions of the photoresist that have been exposed to light. The desired configuration of elements in layer 21a determines where the photoresist is exposed. Photoresist is a polymeric mixture that is deposited as a thin layer, perhaps one μ m thick, upon the multi-layer device. Irradiation with light in the near ultraviolet region of the spectrum modifies the chemical properties of the photoresist, and in "positive" photoresist, makes it more soluble to certain developers. Thus, one step frequently employed in microstructure fabrication is the projection of the image of a mask onto the photoresist layer. It becomes possible to remove the exposed region of the photoresist by dissolving it with a suitable developer.
The removal of the exposed photoresist is shown in Figure 4(c). Etches can then remove portions of layer 21a that were below light exposed areas of the photoresist layer. The removal of these portions of layer 21a is shown in Figure 4(d). Photoresist is resistant to the etches and the portions of layer 21a that are below the unexposed areas of the photoresist are not affected by the etches.
After etching, a solvent can remove the remaining photoresist, potentially leaving layer 21a with a desired configuration. Importantly, this process can produce defects in elements located in layer 21a. In the example shown, element 21 has at least one defect in that it is too wide. The multi-layer device of Figure 4(a) with a configured layer 21a and the remaining photoresist removed is shown in Figure 4(e).
At the point in the fabrication process shown in Figure 4(e), a second patterning step has been completed. This second step forms a second structural element, the write head, 21. In one embodiment, forming the second structural element completes the second patterning step. In another embodiment, the second patterning step also includes forming a second marker element at a known distance and direction from the second structural element. In the latter embodiment, both elements exist in a common layer 21a.
Thus, in the illustrated embodiment of Figures 2 - 4(e), the invention is understood as a lithographic process including the steps of 1) patterning in a first common lithographic layer 1 la, a first structural element 11 (e.g. a read head) and, at a known distance and direction, a first marker element 11a; and 2) patterning in a second common lithographic layer 21a, a second structural element 21 (e.g. a write head) and a second marker element 22. Importantly, the above patterning steps provide the structural and marker elements so that they intersect a single geometrical surface 32 that extends transversely to the first and second lithographic layers. In a preferred embodiment, the geometrical surface is planar. Thus, viewing the second structural element and the first marker element and at least one of the second structural element and the second marker element, at the geometrical surface (i.e. from the X-Y plane), provides information for locating the second structural element relative to the first structural element. In one embodiment, the second structural element and the second marker element are the same element. In another embodiment, the second marker element is located at a known distance and direction relative to the second structural element.
In the illustrated embodiment of Figures 2 - 4(e), the process includes the further step of providing the marker elements with selected spatial overlap along a second axis that extends transversely to the first and second lithographic layers. In the illustrated embodiment, the second axis is substantially parallel to the Y axis. Furthermore, in this embodiment, the process includes yet a further step of providing the structural elements with selected overlap along an axis substantially parallel to the second axis.
Figure 5 is a perspective view of the multi-layer device of Figure 3(b) after cleaving the device to expose the read and write heads and their associated marker elements. Figure 6 shows the cleaved, multi-layer device of Figure 5, as seen from the plane of the cleaved surface (which, in the illustrated embodiment, is substantially the same as the plane of the magnetic medium). In a preferred embodiment as shown, a first layer 11a includes a first structural element 11 and, at a known distance (dl) along a third axis, a first marker element 12. The third axis is substantially parallel to the layers and to the geometrical surface 32. In the embodiment shown in Figure 5, the third axis is the X axis. A second layer 21a includes a second structural element 21 and, at a known distance (d2) along the third axis, a second marker element 22. The separation of the marker elements along the third axis is Δdm. The separation of the structural elements along the third axis is Δds. The multi-layer device illustrated in Figures 5 and 6 contains a write head that is too wide along the illustrated X axis to produce narrow tracks of data. Furthermore, manufacturers desire a specific X axis separation between the centers of the write head 21 and the read head 11. To provide the desired pole-tip configuration, the multi-layer device is inserted into a focused particle beam system according to the invention.
Figure 7 shows the focused particle beam system 70 for providing a desired pole- tip configuration and for manufacturing the thin-film recording head of Figure 1. The illustrated system 70 includes an ion column 72, a vacuum chamber 82, an optional reactant material delivery system 94 and user control station 110. The system 70 provides a focused particle beam system that can precisely mill thin-film recording heads, including thin-film recording heads having contoured surfaces. A recording head contained within a multi-layer device is seated within the vacuum chamber 82 and operated on by a particle beam generated by the column 72 to mill the pole-tip assembly of the recording head. For clarity, Figure 1 shows an example of a recording head 13 that can be seated within chamber 82 and processed by the system 70. A focused ion beam system 70 of this type is commercially available from Micrion Corp. of Peabody, Mass.
The ion column 72 includes an ion source 74, an extraction electrode 76, a focusing element 78, deflection elements 79, and a focused ion beam 80. The ion column 72 sits above the vacuum chamber 82, and the vacuum chamber 82 houses a stage 84, a platform 86, a read/write head 90, a secondary particle detector 88 and a charge neutralization element 92. As further depicted by Figure 7, the optional reactant material delivery system 94 includes a reservoir 96, a manometer 100, a motorized valve element 102, and delivery conduit 104. The user control station 110 can include a processor 112, a pattern recognition element 114, a memory element 116, a display element 120, a scan generator element 122, and dwell registers 124. The operation of the ion column 72, charge neutralization element 92, and secondary particle detector 88 are controlled by the control station 110. The depicted control station 110 includes a processor element 112 that has a scan generator element 122 that includes dwell register 124. The processor element 112 couples via a transmission path to a control element 118 coupled to the ion beam column 72. The processor element includes a location processor element 115. The depicted processor element 112 can be a conventional computer processor element that includes a CPU element, a program memory, a data memory, and an input/output device. One suitable processor element 112 is a IBM Rise 6000 Workstation operating a Unix operating system. As further depicted by Figure 7, the processor element 112 can connect, via the input/output device to a scan generator element 122. In one embodiment, the scan generator element is a circuit card assembly that connects to the processor 112 via the processor input/output device. The circuit card assembly scan generator element 122 depicted in Figure 7 includes a scan memory for storing data representative of a scanning pattern that can be implemented by system 70 for scanning ion beam 80 across the surface of the workpiece 90 to selectively mill, or etch the surface of the workpiece 90. The scan generator board element 122 depicted in Figure 7 can be a conventional computer memory circuit card having sufficient memory for storing digital data information representative of locations of the recording head that are to be processed by the particle beam system 70. Typically, a scan generator board suitable for practice with the present invention includes a series of memory locations, each of which corresponds to a location on the recording head surface. Each memory location stores data representative of an X and Y location of the recording head and preferably further has, for each X and Y location, a dwell register for storing digital data representative of a time for maintaining the particle beam on the surface of the recording head at the location represented by the associated X, Y pair. Accordingly, the dwell register provides a memory location for storing a dwell time for applying the focused particle beam to the surface of the recording head, to thereby allow control of the dose delivered to the recording head."
It will be apparent to one of ordinary skill in the art of focused particle beam processes and systems that the dose delivered to a location on a workpiece surface can be understood to determine generally the depth to which material is removed from that location of the workpiece. Accordingly, the dwell time signal stored in the dwell register can also be understood as representative of a depth, or Z dimension, for the particle beam milling process. Consequently, the processor 112 that couples to such a scan generator board 122 provides a multi-dimensional milling element for generating milling signals that can control in three dimensions the milling or etching process of the focused particle beam system.
Accordingly, the processor 112 employs the X, Y and Z data maintained by the scan generator board 122 to generate milling signals that are transmitted via the transmission path 126 to the control element 118 of the ion column 72. In the depicted embodiment, the milling signals provide control element 118 with information for operating the deflector elements 79 to deflect the focused particle beam for scanning or rasterizing the focused particle beam across the surface of the recording head 90, and to maintain the particle beam at the selected location for a specified dwell time to provide milling to a selected depth. The surface of the recording head 90 generally corresponds to a two-dimensional plane that can be defined by an orthogonal pair of -Y and Faxes. A Z axis, that is generally understood as extending parallel to the path of the focused ion beam 80 is also generally orthogonal to the plane defined by the X and Y axis of the surface of the recording head 90. By controlling the location of the particle beam 80 and the period of time for which the beam 80 impacts against the surface of the recording head 90, material at selected locations of the recording head 90 can be removed. Accordingly, the system 70 provides multidimensional control of the milling process to thereby allow the particle beam 80 to remove selected portions of the recording head surface and form a precise shape of the recording head pole-tip assembly.
Although Figure 7 depicts an ion column 72 that includes deflection elements 79 for deflecting an ion beam 80 to scan across the surface of the recording head 90 and thereby direct the focused ion beam to a selected location on the surface of the recording head 90, it will be apparent to one of ordinary skill in the art of focused particle beam processing that any system suitable for directing the focused particle beam to select locations of the recording head surface can be practiced with the invention. For example, in an alternative embodiment, the platform 84 can be moved in an X, Y or Z space which corresponds to the X, Y and Z space of the milling process and the milling signals generated by the processor 112 can be provided to a stage control system that moves the stage carrying the recording head 90 to thereby dispose a selected portion of the recording head directly in the path of the focused particle beam to mill the recording head 90. Other systems and methods for directing the particle beam can be practiced with the present invention without departing from the scope thereof.
Further it will be apparent to one of ordinary skill in the art of particle beam processes and systems that the depicted scan generator element 122 that is illustrated as a circuit card assembly of read/write computer memory can alternatively be implemented as software program code that runs on a computer platform having an accessible data memory that is configured by the program code to provide storage locations for storing the data representative of the X and Y locations as well as data representative of the dwell time. Such a modification is well within the art of one of ordinary skill and does not depart from the scope of the invention.
The above-described focused particle system of Figure 7 can operate on the cleaved multi-layer device 31a of Figure 6. Figure 8 is a flow chart illustration of one process according to the invention for manufacturing recording heads using system 70 of Figure 7. As depicted in the flow chart and with reference to the preceding figures, one process according to the invention comprises the following steps: Step one 92) pattern a multi-layer lithographically fabricated device with structural and marker elements disposed in the manner described above and illustrated in Figures 3(a) - 4(b); Step two 94) cleave the multi-layer device to expose a geometrical surface that extends transversely to the layers and that substantially contains the structural and marker elements as illustrated in Figures 4(b)-6; Step three 96) generate images of the marker elements of Figure 6 by scanning the ion beam of Figure 7 in the vicinity of the marker elements and by detecting secondary particles emitted as a result of the ion bombardment, and generate, using the location processor 115 of Figure 7, X & Y marker coordinates based on the marker element images; Step four 98) generate, also using the location processor 115, X & Y milling coordinate instructions for the second structural element based on the X & Y marker coordinates; and Step five 100) scan the ion beam of Figure 7 to mill the second structural element of Figure 6 without irradiating the first structural element. In another embodiment of the invention, step three 96 of the process outlined in Figure 8 includes the further step of generating an image of the second structural element.
Returning to Figure 6, it shows trim outlines 82a and 82b over portions of the write head. Each trim outline 82a and 82b represents a selected portion of the recording head to be removed by a focused particle beam milling process. Importantly, the trim outlines can have a variety of geometrical shapes including rectangular, square, and polygonal. In the depicted embodiment, the trim outlines 82a and 82b identify two etching areas. Within these etching areas a focused particle beam will selectively remove portions of the write head to provide a pole-tip assembly that has a desired configuration. A desired pole-tip configuration can include a specified separation of the read and write heads along the second axis.
Figure 9 shows the process of a raster scan of a focused particle beam within the trim outlines of Figure 6. With reference to Figure 7, the trim outlines 82a and 82b represent where the focused particle beam will mill the multi-layer device. The processor 112, based on the X & Y marker coordinates, directs the particle beam 80 to mill the surface of the recording head 90 in accordance with the trim outlines. Again, it is important to note that the trim outlines do not have to be rectangular as shown. The trim outlines can have a variety of geometrical shapes. In one embodiment, the processor 112 generates a series of milling instructions for operating the ion column 72 to implement a digital raster pattern as depicted in Figure 9. Figure 9 illustrates a digital raster pattern 82 that comprises a series of pixel locations 84 with a corresponding pitch 86. The digital raster pattern shown is a serpentine raster pattern. However, manufacturers can employ a variety of raster patterns including a spiral pattern. Furthermore, the pitch is usually smaller than the beam spot size. A typical beam spot size is between approximately .7 microns and .2 microns. As depicted in Figure 9, the processor element 112 generates a set of milling instructions which represent the X and Y locations for directing the particle beam 80 to mill the surface of the recording head 90 and remove the portion of the recording head outlined by the trim outlines 82a, 82b. Importantly, the processor is programmable.
Figure 10(a) is a view of one embodiment of the recording head of Figure 1 seen from the plane of the magnetic medium with the pole-tip configuration represented in Figure 6 changed due to focused particle beam milling. The focused particle beam system 70 has selectively removed portions of the write head 21 so as to produce a desired configuration of the recording head and a desired separation of the read and write head along the third axis, illustrated as the X axis.
Figure 10(b) is another embodiment of the multi-layer lithographically fabricated device of according to the invention. This multi-layer device is similar to the device of Figure 3b. This multi-layer device is different from the device shown in Figure 3b in that it does not contain a second marker element 22. Figure 10(b) includes a first structural element 11 , a second structural element 21. and a first marker element 21.
Figure 10(c) shows the first two steps in a four step process for fabricating the thin-film recording head of Figure 2 using the multi-layer device of Figure 10(b). In the first step 91 , the focused ion beam system 70 locates the top edge of layer 24a. The system 70 locates the top edge of layer 24a by imaging a vertical section 99 of the multilayer device avoiding the structural and marker elements. For example, the system can image a vertical section on the far left side 99 of the multi-layer device. In the second step 93., having located the upper edge of layer 24a, the system obtains a vertical reference point. In the illustrated embodiment, the vertical axis is the Y axis. Having obtained a vertical reference point, the system can then image a horizontal section 89 of the multi-layer device, the vertical location of the horizontal section being appropriately located to image the second structural element 21, based on the previously determined location of the upper edge of layer 24a. From the horizontal section image, the system 70 obtains the center point of element 21.
Figure 10(d) shows the last two steps in a four step process of the fabrication of the thin-film recording head of Figure 2 from the multi-layer device of Figure 10(a). In a third step 95, the system 70 images a section 87 avoiding the first structural element 1 1 and locating element 12. In a fourth step 97, the system 70 determines the location of second structural element 21 , places trim outlines 82a, and mills element 21 to produce a desired pole-tip configuration including a correct offset between the structural elements.
Figures 10(f), 10(g) and 10(h), illustrate sequential steps for manufacturing a thin-film recording transducer in one version of a method according to the present invention. Figure 10(k) is a flow chart that illustrates one embodiment of the method illustrated in Figures 10(f), 10(g) and 10(h). With reference to Figures 1, 2, 7, 10(e)- 10(h) and 10(k), the method disposes a multi-layer device 310 that forms a recording transducer 13 on a platform 86 for contact with the particle beam 80. The multi-layer device 310, as shown in Figure 10(e), has a first layer 312 including a first structural element 314, a second layer 316 including a second structural element 318, and a shielding layer 320. The shielding layer 320 includes a shielding element 322 located between the first structural element 314 and the second structural element 318. In other words, the shielding layer 320 is between the first layer 312 and the second layer 316, and the shielding element 322 in the shielding layer 320 is between the first structural element 314 and the second structural element 318. The first structural element 314 and the second structural element 318 can be a read pole and a write pole, respectively, of a pole-tip assembly. Geometrical surface 381 that is shown in Figure 10(e) corresponds to surface 32 in Figures 3 A and 3B. The structural elements 314, 318 and the shielding element 322 intersect the geometrical surface 381. The geometrical surface extends transversely to the first, second, and shielding layers 312, 316, 320. Thus, imaging at least a portion of the shielding element 322, at the geometrical surface 381, provides information to facilitate imaging the second structural element 318 without requiring irradiation of the first structural element 314.
With reference again to Figures 1, 2, 7, 10(e)- 10(h) and 10(k), and with particular emphasis on Figure 10(k), the illustrated method in operation 200 scans the focused particle beam 80 over the geometrical surface 381 at a selected portion that includes at least a first portion of the shielding element 322 and that does not include the first structural element 314. The method, in operation 200, generates a first image signal representative of the first portion of the shielding element 322. The first image signal results from interaction of the focused particle beam 80 with the first portion of the shielding element 322. The method, in operation 202, analyzes the first image signal of the first portion of the shielding element 322 to determine the location of the first portion of the shielding element 322.
The method, in operation 204, directs the focused particle beam 80, in response to the determined location of the portion of the shielding element 322, to interact with the second structural element 318 without substantially interacting with the first structural element 314. The method, in operation 204, generates a second image signal responsive to interaction of the focused particle beam 80 with the second structural element 318. The method, in operation 208, analyzes the second image signal of the second structural element 318 to determine the location and the shape of the second structural element 318. Then, the method, in operation 210, generates a milling signal, in response to the location and shape of the second structural element 318. The milling signal represents an instruction for applying the focused particle beam 80 to a selected portion of the second structural element 318 for shaping the pole-tip assembly by milling the selected portion of the recording transducer 90.
The scanning operation 200 is facilitated by the use of a cell. A cell describes a selected geometric area that the focused particle beam of the system is allowed to scan. A cell can also represent a set of actions, e.g., etching and imaging, that are performed within that selected geometric area. A cell can include the whole field of view (FOV) of the focused particle beam or any subset thereof. Figure 4B shows a FON cell 330 that spans the entire FOV of the focused particle beam. A second cell, e.g., cell 332, can be located within the FOV cell 330. Further, a second cell can be placed on top of, or adjacent to, a first cell.
A cell can be static or dynamic. A dynamic cell has the property that the shape, location, or function of the cell can be determined by a feature or structure found in, or action performed in, another cell. The process according to the invention wherein the shape and the function of a cell are set dynamically is termed dynamic selective imaging. One example of dynamic selective imaging is when a focused particle beam system according to the invention images a first section of a FOV and selects, based on what features or structures are found in the first section, a second section of the FOV to image.
A cell can be placed by a control system. In other words, a control system assists in creating a cell by controlling the electrostatic deflection of the focused ion beam. In other words, the specified control system causes the beam to impinge on that section of the substrate surface which constitutes the desired cell.
A linguistic or abstract description of a typical structure of interest, e.g., a write head, a read head, or a shielding element, is termed a model. A system according to the invention can search in a cell for features that correspond to one or more models. Different characteristics of a feature, such as the size and shape of the feature, can be used to match a feature found in a cell to a model. To determine the size and shape of a feature, the system searches for the edges of a feature located within a particular cell. To search for the edges of a feature, the system detects , among other things, the contrast between a feature and the background. PCT application serial number PCT/US97/06158 filed April 16, 1997, entitled "Thin-Film Magnetic Recording transducers and Systems and Methods for Manufacturing the Same," by inventors C. Libby, D. Yansen, G. Athas, R. Hill, and R. Mello (attorney docket number MIM-049PC), incorporated herein by reference, describes inter alia, the use of pattern recognition in shaping a pole-tip assembly, and, more particularly, the use of pattern recognition in matching a feature to a model. In addition, U.S. Patent application serial number 08/810,837 filed March 4,
1997, entitled "Thin-Film Magnetic Recording transducer Manufacture," by C. Libby and R. Lee (attorney docket number MIM-056), incorporated herein by reference, describes, inter alia, incorporating at least one fiducial or reference mark in a multi-layer device to facilitate manufacturing of improved thin-film magnetic recording transducers. More specifically, the above-referenced application describes milling a second structural element without irradiating a first structural element by placing a first marker element, which can be imaged and/or damaged, in the same layer of a multi-layer lithographically fabricated device as the first structural element.
The marker element has a fixed spatial relationship to the first structural element. Thus, by imaging the first marker element and the second structural element, and knowing the separation between the first structural element and the first marker element, a focused particle beam system can determine the relative location of the first and second structural elements. Consequently, the focused particle beam system can determine, without irradiating the sensitive first structural element of a wafer with a marker element, which portions of the second structural element require milling. However, there remains a need for a system that can determine which portions of a second structural element require milling, without irradiating a sensitive first structural element of a multi-layer device containing a recording transducer, e.g., a wafer, when the multilayer device does not include the marker element described above.
According to the present invention, selective imaging can be performed on thin- film heads, using a shielding element to indicate where to image a second structural element, without irradiating a first structural element. With reference to Figures 2, 7, and 10(f)- 10(h), in one process according to the invention, the focused ion beam system 70 performs the following steps. 1) The system moves the ion column 72 so that the FOV consists of FOV cell 330 having a predetermined size, e.g. 10 microns by 10 microns. 2) The system 70 images a shielding element search cell 332 which is located within FOV cell 330. Using a known method, such as an optical microscope registration technique, the system selects a first section of the geometrical surface 381 that does not include the first structural element 314. Thus, as an example, the system images a vertical section on the far left side of the multi-layer device shown in Figure 10(f). 3) The system searches for a feature that matches a model 350, e.g., a shielding element
> model. Upon matching the feature to the model, the system locates the top edge 322b of the shielding element 322 within cell 332. 4) If a feature matching model 350 is not located, the system moves the cell 332 systematically, still avoiding irradiating the first structural element 314, and repeats steps 2 and 3 until the top edge 322b of shielding element 322 is located. 5) The system then places a second structural element search cell 334 above the shielding element 322, on the side of the shielding element opposite the first structural element 314. 6) The system images cell 334. 7) The system searches for model 352, e.g. a write pole model. 8) If a feature matching model 352 is not found, the system moves cell 334 systematically, still avoiding irradiating the first structural element 314, and repeats steps 7 and 8 until model 352 is found. 9) The system attaches trim boxes 340 and 342 to the second structural element 318, based, in part, on the image of the second structural element 318 in cell 334. According to another embodiment of the invention, the focused ion beam system 70 performs selective imaging according to the following steps. 1) The system moves to cell 330, without imaging cell 330. 2) The system 70 images cell 332, which is located within cell 330, a selected distance from the first structural element. Cell 332 can be a tall, thin cell located in the periphery of cell 330, spanning the entire height of cell 330. 3) The system searches for model 350, a shielding element. Upon matching the feature to the model, the system locates the top edge 322b of the shielding element 122 within cell 332. 4) If a feature matching model 350 is not located, the system moves cell 332 systematically, still avoiding irradiating the first structural element 314, and repeats steps 2 and 3 until the top edge 322b of shielding element 322 is found. 5) The system 70 images cell 336, which is located within FOV cell 330, a selected distance from the first structural element 314. Cell 336 can be a tall, thin cell located in the periphery of cell 330, opposite cell 332, spanning the entire height of cell 330. 6) The system searches for a feature that matches model 350, e.g. a shielding element. Upon matching the feature to the model, the system locates the top edge 322b of the shielding element 322 within cell 336. 7) If a feature matching model 350 is not located, the system moves cell 332 systematically, still avoiding irradiating the first structural element, and repeats steps 5 and 6 until the top edge 322b of shielding element 322 is found. 8) The system places cell 334 above the shielding element 322, on the side of the shielding element opposite the first structural element 314. 9) The system images cell 334. 10) The system searches for a feature that matches model 352, e.g., a write pole model. 11) If a feature matching model 352 is not found, the system moves cell 334 systematically, still avoiding irradiating the first structural element 314, and repeats steps 9 and 10 until a second structural element is found. 12) The system attaches trim boxes 340 and 342 to the second structural element 318 based, in part, on the image of the second structural element 318.
In one embodiment, the processor 112 includes a trim outline element that employs the geometric pattern information of the write head to generate a geometric pattern or trim outline that represents a selected portion of the write head that is to be milled. The processor 112 generates from this trim outline a series of milling instructions that are transmitted via transmission path 126 to the control element 118 of the ion column 72. The milling instructions can include deflection signals that cause the deflection elements 79 to scan across the surface of the recording transducer 90 according to the geometric pattern determined by the processor 112. In this way, the processor 112 generates milling instructions that direct the ion beam 80 to etch away a selected portion of the recording transducer 90. The processor element 112 can find features that vary in size and position. The processor element 112 can apply a trim outline to the actual features found. The placement and size of the trim outline is determined by "pinning" edges of the template to edges of the outline that the pattern recognition element has found. The processor's pinning operation can be understood as a logical attachment of a trim outline edge to the outline of the feature that the pattern recognition element has found. This attachment will allow the trim outline to correspond to a particular feature. Pins can cause a trim outline to "shrink wrap" around a portion of the detected feature. In addition the system can apply constraints. A constraint is a required fixed dimension between two trim outlines. A constraint overrides any pin actions. If a desired pole-tip configuration requires a specific dimension, which is often the case, a constraint may be applied to ensure that, as a result of pinning, the required dimension remains intact. Accordingly, a milling pattern made up of adaptable trim outlines can adapt to produce a desired read/write head configuration. In other words, by using pins and constraints, similar patterns or features can be milled from features of varying configurations.
As will be seen from the above description, the system 70 depicted in Figure 1 provides a system for manufacturing thin-film magnetic read/write heads that automatically identifies the location and geometry of a second structural element, and generates, from the location and geometry, a set of milling signals that direct the focused particle beam to mill the recording transducer and thereby form a pole-tip assembly that has the precise geometry suitable for generating a selected magnetic field pattern. One such operation is illustrated in Figures 10(f), 10(g), and 10(h).
In the depicted embodiment, a registration post is disposed sufficiently far from the pole-tip assembly of the recording transducer that a first image is taken with sufficiently low magnification as to generate an image that encompasses both the registration post and a portion of the read/write head. In a subsequent step, the pattern recognition element 114 generates a second image that represents, at a higher magnification, the pole-tip assembly 14 of the read/write head. At such a high magnification, the registration post does not appear within the borders of the image. The pattern recognition element 114 passes the geometric pattern information depicted in Figure 10(g) to the processor element 112. The processor element 112 generates a trim outline signal, depicted in Figure 10(h), that includes a first trim outline 340 and a second trim outline 342, each of which represents geometric patterns superimposed over the image of the pole-tip assembly 14. Each trim outline 340 and 342 further represents a selected portion of the recording transducer to be removed by the ion milling process. In the depicted embodiment, the trim outlines 340 and 342 of Figure 10(h) identify two etching areas that will selectively remove portions of the second structural element.
The processor 112 generates from the trim outline signals 340 and 342 a set of milling instructions for directing the particle beam 80 to mill the surface of the recording transducer 90. In one embodiment, the processor 112 generates a series of milling instructions for operating the ion column 72 to implement a digital raster pattern as depicted in Figure 9. Figure 9 illustrates a digital raster pattern 82a that comprises a series of pixel locations 82, each corresponding to the spot size of the ion beam 80, and separated by a pitch 86 which in the depicted digital raster pattern 82 is similarly sized to the beam spot size, and preferably small enough to allow for overlap during the milling process. One such beam spot size is approximately .7 microns. As depicted in Figure 9, the processor element 112 therefore generates from the trim outline 340 a set of milling instructions which represent the X and Y locations for directing the particle beam 80 to mill the surface of the recording transducer 90 and remove the portion of the recording transducer outlined by the trim outline signal 340.
Figures 10(i) and 10(j) depict a magnetoresistive transducer before and after being milled by a system according to the invention to selectively remove portions of the recording transducer surface. As depicted by Figure 10(j), the focused particle beam has removed two rectangular portions from either side of the write head and part of the upper shield to reduce the track width. One of the concerns with milling these devices is protecting the electrically sensitive magnetoresistive sensors from electrostatic discharge (ESD) damage. Each milled portion depicted in Figure 10(j) corresponds to the depicted trim outlines 340 and 342 depicted in Figure 10(h). In the embodiment illustrated in Figures 10(i) and 10(j), the milling signals generated by the processor 112 direct the particle beam 80 to mill the workpiece to substantially the same depth over the entire portion of the trim outline. Accordingly, the write pole has an upper surface and a recessed lower surface.
As can be seen from the above description, the invention provides improved systems and methods for forming thin film recording transducers and for employing a focused particle beam to manufacture thin-film recording transducers. It will be appreciated by those skilled in the art of thin film recording manufacturing techniques that changes can be made to the embodiments and processes described above without departing from the broad inventive concept thereof. It will further be understood therefore, that the invention is not to be limited to the particular embodiments disclosed herein but is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims

What is claimed is:
1. A multi-layer lithographically fabricated device comprising a first layer, said first layer including a first structural element and, at a known distance and direction relative thereto, a first marker element, and a second layer, said second layer including a second structural element, said structural elements and said marker element intersecting a geometrical surface that extends transversely to said first and second layers, so that viewing said first marker element and said second structural element, at said geometrical surface, provides information for locating said second structural element relative to said first structural element.
2. The multi-layer lithographically fabricated device according to claim 1, in which the second layer includes a second marker element located at a known distance and direction relative to said second structural element, said structural elements and said marker elements intersecting a geometrical surface that extends transversely to said first and second layers, so that viewing said first and second marker elements, at said geometrical surface, provides information for locating said second structural element relative to said first structural element.
3. The multi-layer lithographically fabricated device according to claim 1, in which said first and second structural elements are recording transducer elements, and said marker element is adapted for imaging by a focused particle beam system.
4. Apparatus for shaping a pole-tip assembly of a recording transducer with a focused particle beam, said apparatus comprising a focused particle beam for selectively interacting with a multi-layer device, said multi-layer device including a first layer, said first layer including a first structural element and, at a known distance and direction relative thereto, a first marker element, and a second layer, said second layer including a second structural element and a second marker element, said structural elements and said marker elements intersecting a geometrical surface that extends transversely to said first and second layers, so that viewing said first marker element and said second structural element, at said geometrical surface, provides information for locating said second structural element relative to said first structural element, means for generating image signals responsive to said focused particle beams interaction with said first marker element and at least one of said second structural element and said second marker element on said multi-layer device and for generating, responsive to said image signals, a coordinate signal representative of a position of said second structural element relative to said first structural element and relative to said focused particle beam; and processor means responsive to said coordinate signal for generating a milling signal representative of an instruction for applying said focused particle beam to a selected portion of said second structural element for milling said selected portion of said second structural element.
5. Apparatus of claim 4, wherein said second structural element and said second marker element are the same element.
6. Apparatus of claim 4, wherein said second marker element is located at a known distance and direction relative to said second structural element.
7. A lithographic process for fabricating thin-film magnetic recording transducers, said process having the improvement comprising the steps of a) in a first lithographic step, patterning a first structural element and, at a known distance and direction relative thereto, patterning a first marker element, where said first structural element and said first marker element are on a common first lithographically formed layer, and b) in a second lithographic step, patterning a second structural element, where said second structural element is on a second lithographically formed layer different from said first layer, c) said patterning steps providing said structural elements and said marker element located to intersect a geometrical surface that extends transversely to said first and second layers, so that viewing said first marker element and said second structural element, at said geometrical surface, provides information for locating said second structural element relative to said first structural element.
8. The lithographic process of claim 7, in which said geometrical surface is substantially planar.
9. The lithographic process of claim 7, including the further step of cleaving said first and second layers along said geometrical surface.
10. The lithographic process of claim 7, wherein the second lithographic step includes the further step of patterning a second marker element at a know distance and direction relative to said second structural element, where said second structural element and said second marker element are on a common second lithographically formed layer different from said first layer, said patterning steps providing said structural elements and said marker elements located to intersect a geometrical surface that extends transversely to said first and second layers, so that viewing said first and second marker elements, at said geometrical surface, provides information for locating said second structural element relative to said first structural element.
11. The lithographic process of claim 10, including the further step of providing said marker elements with selected spatial overlap along a first axis.
12. The lithographic process of claim 11, including the further step of providing said first and second structural elements with selected spatial overlap along an axis parallel to said first axis.
13. A process for locating a second structural element with respect to a first structural element in a multi-layer lithographically fabricated device, comprising the steps of a) imaging, with a focused particle beam, a first marker element and at least one of said second structural element and a second marker element on said device, said first structural element being in a first layer, and said first marker element being in said first layer at a known distance and direction from said first structural element, said second structural element being in a second layer, and said second marker element being in said second layer, said structural elements and said marker elements intersecting a geometrical surface that extends transversely to said first and second layers, and b) determining, responsive to said imaging step, the location of said second structural element relative to the location of said first structural element.
14. The process of claim 12, wherein said step of determining the location of said second structural element relative to the location of said first structural element includes the step of processing information regarding the location of said marker elements derived from imaging said first marker element and at least one of said second structural element and said second marker element.
15. The process of claim 13, wherein said second structural element and said second marker element are the same element.
16. The process of claim 13, wherein said second marker element is located at a known distance and direction relative to said second structural element, and wherein said imaging step images said first and second marker elements and does not image said second structural element.
17. A process for employing a focused particle beam in the manufacture of a magnetic recording transducer, said process having the improvement comprising the steps of a) forming a multi-layer substrate having, in a first layer, a first structural element and, at a known distance and direction relative thereto, a first marker element, and having, in a different second layer, a second structural element and a second marker element, and having said structural elements and said marker elements intersecting a geometrical surface that extends transversely to said first and second layers, b) cleaving said substrate along a surface that includes said first and second structural elements and said first and second marker elements, c) imaging, with a focused beam, said first marker element and at least one of said second structural element and said second marker element at said surface, d) determining, in response to said imaging step, a location, on said surface, of said second structural element relative to said first structural element, and e) applying said focused particle beam to a selected portion of said second structural element on said surface for the relative configuring of said second structural element by milling said selected portion of said second structural element.
18. The process of claim 17, wherein said second structural element and said second marker element are the same element.
19. The process of claim 17, wherein said second marker element is located at a known distance and direction relative to said second structural element.
20. The process of claim 19, wherein the step of imaging further includes imaging both said second structural element and said second marker element on said multi-layer device.
21. Apparatus for shaping a pole-tip assembly of a recording transducer with a focused particle beam, said apparatus comprising a platform for receiving a multi-layer device including said recording transducer and for disposing said multi-layer device for interaction with said focused particle beam, said multi-layer device having a first layer including a first structural element, a second layer including a second structural element, and a shielding layer including a shielding element, said shielding element located between said first structural element and said second structural element, said structural elements and said shielding element intersecting a geometrical surface that extends transversely to said first, second, and shielding layers, so that imaging at least a portion of said shielding element, at said geometrical surface, provides information that facilitates imaging said second structural element without imaging said first structural element, means for scanning said focused particle beam over said geometrical surface at a selected section that includes at least a portion of said shielding element and that does not include said first structural element, means for generating a first image signal of said portion of said shielding element responsive to interaction of said focused particle beam with said shielding element, means for analyzing the first image signal of said portion of said shielding element to determine the location of said portion of said shielding element, means for directing, responsive to said determined location of said portion of said shielding element, said focused particle beam to interact with said second structural element without substantially interacting with said first structural element, means for generating a second image signal responsive to interaction of said focused particle beam with said second structural element, and processor means responsive to said second image signal for generating a milling signal representative of an instruction for applying said focused particle beam to a selected portion of said second structural element for milling said selected portion of said second structural element.
22. A focused particle beam process for shaping a pole-tip assembly of a recording transducer, comprising the steps of disposing a multi-layer device forming said recording transducer on a platform for exposure to said particle beam, said multi-layer device having a first layer including a first structural element, a second layer including a second structural element, and a shielding layer including a shielding element located between said first structural element and said second structural element, said structural elements and said shielding element intersecting a geometrical surface that extends transversely to said first, second, and shielding layers, so that imaging at least a portion of said shielding element, at said geometrical surface, provides information that facilitates imaging said second structural element without imaging said first structural element, scanning said focused particle beam over said geometrical surface at a selected section that includes at least said portion of said shielding element and that does not include said first structural element, generating a first image signal of said portion of said shielding element responsive to interaction of said focused particle beam with said portion of said shielding element, analyzing the first image signal of said portion of said shielding element to determine the location of said portion of said shielding element, directing, responsive to said determined location of said portion of said shielding element, said focused particle beam to interact with said second structural element without substantially interacting with said first structural element, generating a second image signal responsive to interaction of said focused particle beam with said second structural element, and generating, responsive to said second image signal, milling signals representative of an instruction for applying said focused particle beam to a selected portion of said second structural element for shaping said pole-tip assembly by milling said selected portion of said recording transducer.
23. A process according to claim 22 wherein said portion of said shielding element is a portion of said shielding element closest to said second structural element.
24. Apparatus for shaping a pole-tip assembly of a recording transducer with a focused particle beam, said apparatus comprising a platform for receiving a multi-layer device including said recording transducer and for disposing said multi-layer device for interaction with said focused particle beam, said multi-layer device having a first layer including a first structural element, a second layer including a second structural element, and a shielding layer including a shielding element, said shielding element located between said first structural element and said second structural element, said structural elements and said shielding element intersecting a geometrical surface that extends transversely to said first, second, and shielding layers, so that imaging at least a portion of said shielding element, at said geometrical surface, provides information that facilitates imaging said second structural element without imaging said first structural element, means for scanning said focused particle beam over said geometrical surface at a selected section that includes at least a portion of said shielding element and that does not include said first structural element, means for generating a first image signal of said portion of said shielding element responsive to interaction of said focused particle beam with said shielding element, and for generating a second image signal responsive to interaction of said focused particle beam with said second structural element, means for analyzing said first image signal of said portion of said shielding element to determine the location of said portion of said shielding element, means for directing, responsive to said determined location of said portion of said shielding element, said focused particle beam to interact with said second structural element without substantially interacting with said first structural element, said interaction of said focused particle beam with said second structural element resulting in said second image signal, and processor means responsive to said second image signal for generating a milling signal representative of an instruction for applying said focused particle beam to a selected portion of said second structural element for milling said selected portion of said second structural element.
PCT/US1998/003964 1997-03-04 1998-03-02 Thin-film magnetic recording head manufacture WO1998039770A1 (en)

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US08/810,837 US6004437A (en) 1996-04-19 1997-03-04 Thin-film magnetic recording head manufacturing method
US08/810,837 1997-03-04
US87449797A 1997-06-13 1997-06-13
US08/874,497 1997-06-13
US87701997A 1997-06-16 1997-06-16
US08/877,019 1997-06-16

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WO2000041170A3 (en) * 1999-01-06 2000-11-02 Storage Technology Corp Three-dimensional recording heads for control of debris and bidirectional written track width
WO2000057403A3 (en) * 1999-03-24 2001-03-08 Storage Technology Corp Highly aligned thin film tape head and method of making same
US20230197403A1 (en) * 2021-12-16 2023-06-22 Fei Company Microscopy feedback for improved milling accuracy
US11810602B2 (en) 2021-09-09 2023-11-07 International Business Machines Corporation Mechanism to shift the head span of a tape head at a wafer level

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000041170A3 (en) * 1999-01-06 2000-11-02 Storage Technology Corp Three-dimensional recording heads for control of debris and bidirectional written track width
US6191919B1 (en) 1999-01-06 2001-02-20 Storage Technology Corporation Magnetic transducer with debris guiding channels having non-vertical sloping walls formed in a tape bearing surface
WO2000057403A3 (en) * 1999-03-24 2001-03-08 Storage Technology Corp Highly aligned thin film tape head and method of making same
US6362934B1 (en) 1999-03-24 2002-03-26 Storage Technology Corporation Highly aligned thin film tape head and method of making same
US6496329B2 (en) 1999-03-24 2002-12-17 Storage Technology Corporation Highly aligned thin film tape head
US11810602B2 (en) 2021-09-09 2023-11-07 International Business Machines Corporation Mechanism to shift the head span of a tape head at a wafer level
US12073858B2 (en) 2021-09-09 2024-08-27 International Business Machines Corporation Mechanism to shift the head span of a tape head at a wafer level
US20230197403A1 (en) * 2021-12-16 2023-06-22 Fei Company Microscopy feedback for improved milling accuracy
US12249482B2 (en) * 2021-12-16 2025-03-11 Fei Company Microscopy feedback for improved milling accuracy

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