JPH07210834A - Magnetoresistive magnetic head, manufacturing method thereof, and magnetic disk device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a magnetoresistive head having high sensitivity and high reliability, which prevents damage to the magnetoresistive film and deterioration of magnetic properties due to surface cleaning. A magnetoresistive effect film 60 for converting a magnetic signal into an electrical signal by using a magnetoresistive effect, a pair of electrodes for flowing a signal detection current through the magnetoresistive effect film, and the magnetoresistive effect film A magnetic domain control layer 80 arranged at both ends for magnetically applying a bias to the magnetoresistive film in the longitudinal direction.
A magnetoresistive effect magnetic head having a buffer layer 70 made of a ferromagnetic film between the magnetoresistive effect film 60 and the magnetic domain control layer 80.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive effect magnetic head utilizing the magnetoresistive effect used in magnetic recording devices such as magnetic disk devices and magnetic tapes, and a method for manufacturing the same.

[0002]

2. Description of the Related Art The main problem of a magnetoresistive effect magnetic head is that, when a domain wall is present in a magnetoresistive film, the domain wall moves irregularly due to a signal magnetic field from the magnetic surface of a magnetic recording medium, causing Barkhausen noise. Is called noise. Therefore, it is necessary to eliminate the domain wall in the magnetoresistive effect film.

As a method of eliminating the domain wall in the magnetoresistive effect film, US Pat. No. 4,663,685 provides a domain control layer composed of an antiferromagnetic material at both upper ends of the magnetoresistive effect film. , A longitudinal bias magnetic field is applied in the longitudinal direction of the magnetoresistive film by utilizing the magnetic coupling (hereinafter referred to as exchange coupling) generated at the interface between the antiferromagnetic film and the magnetoresistive film. By aligning the magnetic moments in the effect film in one direction (unidirectional anisotropy), the magnetic sensitive part in the center of the magnetoresistive effect film is maintained in a single domain state, and Barkhausen noise is prevented. Has been done. The material proposed in the above US patent is Ni as a magnetoresistive film.
As the Fe and antiferromagnetic film, a Mn alloy is disclosed.
The material having the largest exchange coupling with the magnetoresistive film in the Mn alloy is FeMn.

In order to impart unidirectional anisotropy to the magnetoresistive film, it is necessary to epitaxially grow an antiferromagnetic film on the magnetoresistive film. For that purpose, after forming the magnetoresistive film, it is necessary to continuously deposit or sputter the antiferromagnetic film in the same device.

When manufacturing the magnetoresistive effect element, the antiferromagnetic film is formed after the magnetoresistive effect element is patterned into a predetermined shape. However, in this case, since an oxide film of several nm is formed on the surface of the magnetoresistive film after patterning, magnetic coupling cannot be established even if an antiferromagnetic film is formed thereon.

Therefore, conventionally, the process shown in FIG. 2A has been adopted. That is, the magnetoresistive effect film (MR film)
After patterning, the surface of the magnetoresistive effect film is cleaned to remove the oxide film on the film surface by etching, and then an antiferromagnetic film is formed in the same vacuum device. As the surface cleaning method, a bias sputtering method or an etching method using an Ar electron gun or the like was used.

[0007]

In the above-mentioned conventional method, the process is complicated because the step of cleaning the surface of the magnetoresistive film is included. Furthermore, the magnetoresistive effect film is several tens.
The thickness is as thin as nm or less, and there is a problem that the magnetoresistive effect film is damaged by the plasma at the time of cleaning and the magnetic characteristics are changed.

Further, since the thickness of the oxide film is not constant, when the oxide film is etched, the magnetoresistive effect film is also etched, and not only the magnetic characteristics of the magnetoresistive effect film are deteriorated but also the head characteristics are deteriorated. It will have a big impact.

Further, when the oxide film is cleaned, the entire sample is exposed to the plasma, so that the substrate holder or the substrate surface is etched out and the etch-out substance is redeposited. The reproducibility becomes a problem. As a result, there is a problem that the magnetoresistive film is not in a single magnetic domain state and a magnetic domain wall is generated, and Barkhausen noise is generated.

It is an object of the present invention to use a magnetoresistive effect magnetic head having a structure in which exchange coupling is formed between a magnetoresistive effect film and an antiferromagnetic film with good reproducibility, a method for manufacturing the same, and a method of using the magnetic head. To propose a magnetic disk device that was previously used.

[0011]

Means for Solving the Problems The gist of the present invention for solving the above problems is as follows. That is, a magnetoresistive effect film that converts a magnetic signal into an electrical signal by using the magnetoresistive effect, a pair of electrodes for flowing a signal detection current through the magnetoresistive effect film, and both ends of the magnetoresistive effect film. In a magnetoresistive effect type magnetic head having a magnetic domain control layer for magnetically applying a bias in the longitudinal direction to the magnetoresistive effect film, wherein a ferromagnetic layer is provided between the magnetoresistive effect film and the magnetic domain control layer. A magnetoresistive head is provided with a buffer layer made of a film. The thickness of the buffer layer is preferably 1 to 5 nm.

In the method of manufacturing the magnetoresistive effect magnetic head according to the present invention, as shown in the flow chart of FIG. 2B, the buffer layer 70 is immediately formed after the magnetoresistive effect film 60 is patterned into a predetermined shape. And the magnetic domain control layer 80 are continuously formed, and after being patterned into a predetermined shape, heat treatment is performed while applying a magnetic field in the easy axis direction of the magnetoresistive effect film. That is, the feature of the present invention is to apply the ferromagnetic-ferromagnetic coupling between the magnetoresistive effect film 60 and the buffer layer 70, and obtain stable exchange coupling even through the oxide film.

The heat treatment temperature is 260 to 300 ° C.,
The heat treatment with a holding time of 60 to 20 hours can improve the exchange coupling and the blocking temperature. The magnetic disk device of the present invention can be obtained by mounting the above magnetoresistive magnetic head.

[0014]

After the magnetoresistive effect film is patterned into a predetermined shape, the buffer layer and the antiferromagnetic film which is the magnetic domain control layer are immediately formed in succession in the same vacuum device to form the magnetoresistive effect film surface. The exchange bond between the two can be formed with good reproducibility without cleaning. Therefore, since it is possible to prevent damage to the magnetoresistive film and deterioration of the magnetic characteristics due to surface cleaning according to the conventional method, it is possible to obtain a magnetoresistive magnetic head with high sensitivity and high reliability.

Further, the Barkhausen noise can be prevented from being improved by exchanging exchange coupling by applying an appropriate heat treatment, and since the blocking temperature is improved, the stability due to thermal history is enhanced.

Furthermore, since the surface cleaning of the magnetoresistive effect film can be omitted, the manufacturing process can be shortened.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the magnetoresistive effect type magnetic head of the present invention will be described with reference to FIG.

The magnetoresistive effect magnetic head has a lower magnetic shield film 20 formed on a non-magnetic ceramic substrate 10.
And a lower gap film 30 on the magnetic shield film 20. The soft film 4 is formed on the lower gap film 30.
0, a shunt film 50, and a magnetoresistive effect film 60 are formed.

A separation film 65 disposed at least in the magnetic sensitive portion of the magnetoresistive film 60, and the separation film 65 and the magnetoresistive film 60 are covered on the separation film 65 at predetermined positions at predetermined intervals. The buffer layer 70 and the magnetic domain control layer 80 are formed. Further, a signal reading electrode 90 is formed thereon.

The upper gap film 10 covers the above films.
0, the upper magnetic shield film 110 and the protective film 120 are formed and configured.

Although the magnetoresistive head of FIG. 1 is provided with the separation film 65, the separation film 65 may be omitted.

Next, the function and material of each layer and each film will be described.

The upper magnetic shield film 110 and the lower magnetic shield film 20 have a function of preventing the magnetic resistance effect film 60 from being affected by a magnetic field other than a signal and increasing the signal resolution of the magnetoresistive effect type magnetic head. These materials are NiFe alloys, NiCo alloys, Co-based amorphous alloys, FeSiAl alloys, etc., and their film thickness is about 0.5 to 3 μm.

The upper gap film 100 and the lower gap film 30 which are arranged adjacent to the magnetic shield films 110 and 20 electrically and magnetically connect the magnetoresistive film 60, the upper magnetic shield film 110 and the lower magnetic shield film 20, respectively. And has a non-magnetic insulating material such as glass or Al ₂ O ₃ .

Upper and lower gap films 100 and 3
The film thickness of 0 affects the reproduction and resolution of the magnetoresistive head, and therefore depends on the recording density desired for the magnetic disk device, and is usually in the range of 0.1 to 0.4 μm.

The magnetoresistive film 60 is made of NiFe alloy, Ni
A ferromagnetic film, such as a Co alloy or a NiFeCo alloy, whose electric resistance changes depending on the direction of magnetization is used. Its film thickness is about 0.01 to 0.04 μm.

The shunt film 50 and the soft film 40 have a function of applying a lateral bias magnetic field in order to increase the sensitivity of the magnetoresistive effect film 60. The shunt film is made of Ti, Nb,
A non-magnetic metal film such as Ta or Mo is used, and the film thickness is 0.0
It is 1 to 0.05 μm.

The soft film material is NiFeNb, NiFe
Rh, NiFeCo, CoZrMo, etc. are used,
The film thickness is 0.01 to 0.05 μm. Although the soft film 40 and the shunt film 50 are used as the bias magnetic field applying means in FIG. 1, only one of them may be used.

The separation film 65 is a high resistance metal film such as T.
i, Ta, C, etc., and the insulating film is Al ₂ O ₃ , Si
O ₂ , TiO ₂ , ZrO _{2 and the} like are preferable. Alternatively, the insulating film may be made of a material to which a third element is added.

The buffer layer 70 is made of NiFe alloy, NiC.
A ferromagnetic film such as an o alloy or a NiFeCo alloy is used, and is ferromagnetically coupled to the magnetoresistive film 60 to form the magnetic domain control layer 8.
It has a function of epitaxially growing 0 on the buffer layer 70.

The magnetic domain control layer 80 has a function of applying a longitudinal bias magnetic field in the lengthwise direction to bring the magnetoresistive effect film 60 into a single magnetic domain state. FeMn, CoP as the material
t, CrMn, etc. are used, and the film thickness is 0.01 to 0.0.
It is 3 μm.

The signal detection electrode 90 is the magnetoresistive film 60.
Sufficient current, for example 1 × 10 ^{6 to} 20 × 10 ⁶ A / cm
^{Since 2} is flowed, Cu, Au, N, which usually have low electrical resistance,
A single layer or laminated film of b, Ta, W or the like is used.

Next, a method of manufacturing the magnetoresistive effect magnetic head of the present invention will be described. First, the lower magnetic shield film 20 made of NiFeN and having a film thickness of 0.5 to 3 μm is formed on the substrate 10. A lower gap film 30 such as an Al ₂ O ₃ film is formed on the lower magnetic shield film 20 to have a thickness of 0.1 μm or more. Further, the soft film 40 is made of NiFeNb of 0.02μ.
m, the shunt film 50 is a Ta film of 0.015 μm (0.01
5 to 0.03 μm is also possible), the magnetoresistive film 60 is Ni
An Fe film having a thickness of 0.02 μm is formed and patterned into a predetermined shape by a milling method.

Next, the separation film 6 is formed on the magnetoresistive film 60.
5, for example, an Al ₂ O ₃ film is placed at a predetermined position in an amount of 0.01
5 μm (0.01 to 0.02 μm is acceptable). Here, the separation film 65 is formed so as to be disposed at least at the position of the magnetic sensing portion of the magnetoresistive effect film 60.

Conventionally, as shown in FIG. 2A, the surface of the NiFe film, which is the magnetoresistive effect film 60, is cleaned to remove the oxide film on the surface of the NiFe film, and then on the separation film 65. The magnetic domain control layer 80 was formed of a FeMn film.

According to the present invention, as shown in FIG.
Immediately after patterning the Fe film, the buffer layer 70 is a NiFe film and the FeMn film 0.02 μm (0.01 to 0.03 μm is possible) is continuously formed as the magnetic domain control layer 80 immediately in the same apparatus.

FIG. 3 shows the relationship between the film thickness of the optimum buffer layer and the exchange coupling magnetic field, which is a feature of the present invention.

A NiFe film is used as the magnetoresistive effect film, and a FeMn film is used as the magnetic domain control layer.
An iFe film (hereinafter referred to as a buffer NiFe film) was used.
The NiFe film is processed in the same manner as in a normal patterning process, and an oxide film of several nm is formed on the surface. N
The film thickness of the iFe film and the FeMn film is 0.04 μm. FeM formed on an amorphous base film such as a glass substrate
The n thin film exhibits paramagnetism, and in order to impart unidirectional anisotropy to the NiFe film, the γ-FeMn film which is an antiferromagnetic film is used as N film.
It must be epitaxially grown on the iFe film. Therefore, when the FeMn film is formed directly on the NiFe film whose surface is oxidized by the patterning process, the exchange coupling magnetic field is not generated because the exchange interaction does not occur between the NiFe film and the FeMn film as shown in FIG. It becomes zero.

Therefore, if the same NiFe film is formed as a buffer layer on the NiFe film, it is considered that they are ferromagnetically coupled, and the FeMn film formed on the buffer NiFe film is epitaxially grown to form the NiFe film and the FeMn film. It was found that an exchange bond was formed between them. At this time, the film thickness of the buffer NiFe film needs to be at least 1 nm, and if it is less than that, the buffer NiFe film does not become a continuous film, so that the strength of the exchange coupling between the NiFe film and the FeMn film becomes insufficient. .

The magnitude of exchange coupling is buffer NiF.
The thickness of the e film is about 25 Oe, which is constant within the range of 1 to 5 nm. When the thickness of the buffer NiFe film exceeds 5 nm, for example, when the separation film 65 is provided as shown in FIG. 1, a pole is generated in the buffer NiFe film 70, and the anisotropic portion of the magnetically sensitive portion of the magnetoresistive effect film 60 is generated. The strong magnetic field causes the magnetic characteristics to deteriorate. Further, in the case where the separation film 65 is not provided, the total film thickness of the magnetoresistive effect film becomes large, so that the reproducing characteristic as the magnetic head deteriorates. Therefore, the optimum thickness of the buffer layer is 1 to 5 nm.

After forming the buffer layer 70 and the magnetic domain control layer 80, an electrode 90 is formed and heat treatment is performed in a high vacuum while applying a magnetic field in the easy axis direction of the magnetoresistive effect film 60. The results of examining the optimum heat treatment conditions in that case are shown below.

FIG. 4 shows the relationship between the heat treatment temperature and the blocking temperature of the FeMn film. Here, the blocking temperature is
It shows the temperature at which the unidirectional anisotropy imparted to the NiFe film disappears (the exchange coupling magnetic field becomes zero).

The NiFe film and the FeMn film are continuously formed in the same apparatus, and each has a thickness of 0.04 μm. Further, an Al ₂ O ₃ film was formed on the FeMn film to prevent oxidation, to a thickness of 0.04 μm. The heat treatment was performed while applying an external magnetic field of about 2 to 3 kOe in the easy axis direction of the NiFe film. The holding time is 60 hours.

The magnetoresistive head of FIG. 1 has a write-only magnetic head on the protective film 120.
Since the temperature of this magnetic head during manufacturing rises to about 250 ° C., the blocking temperature must be higher than 250 ° C. The blocking temperature is about 16 immediately after film formation.
Although it is as low as 0 ° C, the blocking temperature becomes high by performing the heat treatment. For example, when the heat treatment temperature is 260 ° C, the blocking temperature becomes about 260 ° C. However, when the heat treatment temperature is 300 ° C. or higher, the magnetoresistive effect film NiF
The magnetic properties of the e film deteriorate. Therefore, the optimum heat treatment temperature when the holding time is 60 hours is 260 to 280 ° C.

Next, FIG. 5 shows the relationship between the heat treatment time and the blocking temperature. Heat treatment temperature is 270 ℃ (●) and 28
At 0 ° C. (∘), the other conditions are the same as above. The blocking temperature is 250 ° C. or higher when the heat treatment temperature is 270 ° C. for about 40 hours and 280 ° C. for about 30 hours, and the holding time may be shortened by increasing the heat treatment temperature. From the above results, the optimum heat treatment temperature is 260 to 300 ° C., and the heat treatment time is 20 to 60 hours.

After the heat treatment, the upper gap film 100 and the upper magnetic shield film 110 are formed to complete the fabrication of the magnetoresistive head of the present invention.

FIG. 6 is a diagram showing a schematic structure of the magnetic disk device of the present invention. The magnetic disk device includes a plurality of magnetic disk groups 2040 stacked on one axis (spindle 2020) at equal intervals, a motor 2030 that drives the spindle 2020, and a voice coil motor 2130 that drives a movable carriage 2060. It includes a magnet 2080, a voice coil 2070, and a base 2010 that supports them.

Further, a voice coil motor control circuit 2090 is provided for controlling the voice coil motor 2130 in accordance with a signal sent from a host device 2120 such as a magnetic disk control device. Furthermore, a function of converting the data sent from the host device 2120 into a current that should be passed through the magnetic head in accordance with the writing method, and the magnetic disk 204
A write / read circuit 2100 having a function of amplifying data sent from 0 and converting it into a digital signal is provided, and this write / read circuit 2100 is connected to a higher-level device 2120 via an interface 2110. .

Next, the operation of this magnetic disk device will be described by taking the case of reading as an example.

The voice coil motor control circuit 209 from the host device 2120 via the interface 2110.
The voice coil motor 21 is controlled by the control current from 0.
30 drives the carriage 2060, and the magnetic head group 2 is moved to the position of the track where the instructed data is stored.
Move 050 and position accurately. This positioning is performed by the positioning magnetic head 2050a connected to the voice coil motor control circuit 2090 detecting and providing the position on the magnetic disk 2040, and the position control of the data magnetic head 2050.

The motor 2030 supported by the base 2010 rotates a plurality of magnetic disks 2040 (diameter 3.5 inches) mounted on the spindle 2020.

Next, in accordance with the signal from the write / read circuit 2100, the designated predetermined magnetic head is selected,
After detecting the head position of the designated area, the data signal on the magnetic disk is read. This reading is performed by the data magnetic head 205 connected to the write / read circuit 2100.
0 is performed by exchanging signals with the magnetic disk 2040. The read data is converted into a predetermined signal and sent to the higher-level device 2120.

As a high-performance magnetic disk device, the areal recording density on the magnetic disk is 50 Mb / in ² or more, the linear recording density is 2.5 kb / in or more, and the track density is 2000.
It is desirable that the number of tracks / in or more.

By using the magnetoresistive effect magnetic head of the present invention, it is possible to manufacture a magnetic disk device having a recording density of 500 Mb / in ² or more.

[0055]

EFFECTS OF THE INVENTION The surface of the magnetoresistive film is cleaned by patterning the magnetoresistive film into a predetermined shape and then continuously forming a buffer layer and an antiferromagnetic film which is a magnetic domain control layer. Therefore, the exchange coupling between the magnetoresistive film and the antiferromagnetic film can be formed with good reproducibility.
As a result, it is possible to prevent damage to the magnetoresistive film and deterioration of the magnetic characteristics due to conventional surface cleaning, and to obtain a highly sensitive and highly reliable magnetoresistive magnetic head.

Further, by optimizing the heat treatment process, the exchange coupling is improved, Barkhausen noise can be prevented, and the blocking temperature is improved, so that the stability against thermal history is increased and the process margin is widened. You can Furthermore, the conventional step of cleaning the surface of the magnetoresistive film can be omitted.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a magnetoresistive effect magnetic head according to an embodiment of the present invention.

2A to 2D are manufacturing process diagrams of a conventional magnetoresistive element and the present invention.

FIG. 3 is a graph showing the thickness of the buffer layer and the strength of the exchange coupling magnetic field when the buffer layer (NiFe film) is interposed.

FIG. 4 is a graph showing the relationship between heat treatment temperature and blocking temperature.

FIG. 5 is a graph showing the relationship between heat treatment time and blocking temperature.

FIG. 6 is a configuration diagram showing an example of a magnetic disk device.

[Explanation of symbols]

10 ... Substrate, 20 ... Lower magnetic shield film, 30 ... Lower gap film, 40 ... Soft film, 50 ... Shunt film, 60 ...
Magnetoresistive film, 65 ... Separation film, 70 ... Buffer layer, 8
0 ... Magnetic domain control layer, 90 ... Electrode, 100 ... Upper gap film, 110 ... Upper magnetic shield film, 120 ... Protective film, 2
010 ... Base, 2020 ... Spindle, 2030 ... Motor, 2040 ... Magnetic disk group, 2050 ... Data magnetic head, 2050a ... Positioning magnetic head, 2
060 ... Carriage, 2070 ... Voice coil, 208
0 ... Magnet, 2090 ... Voice coil motor control circuit, 2100 ... Write / read circuit (R / W electronic circuit), 2110 ... Interface, 2120 ... Host device, 2130 ... Voice coil motor.

Front Page Continuation (72) Inventor Isamu Yuhito 2880 Kozu, Odawara-shi, Kanagawa Stock Company Hitachi Storage Systems Division

Claims (9)

[Claims] 1. A magnetoresistive film for converting a magnetic signal into an electric signal by using the magnetoresistive effect, a pair of electrodes for flowing a signal detection current through the magnetoresistive film, and the magnetoresistive film. In a magnetoresistive effect magnetic head having magnetic domain control layers for magnetically applying a bias to the magnetoresistive film in the longitudinal direction, the magnetoresistive effect magnetic head having a magnetic domain control layer between the magnetoresistive effect film and the magnetic domain control layer. A magnetoresistive head, wherein a buffer layer made of a ferromagnetic film is provided on the magnetic head. 2. The magnetoresistive effect magnetic head according to claim 1, wherein the buffer layer formed of the ferromagnetic film has a film thickness of 1 to 5 nm. 3. The magnetoresistive head according to claim 1, wherein the buffer layer is formed of a film having a film thickness of 1 to 5 nm made of the same material as that of the magnetic domain control layer. 4. A magnetoresistive film that converts a magnetic signal into an electrical signal by using the magnetoresistive effect, a pair of electrodes for flowing a signal detection current through the magnetoresistive film, and the magnetoresistive film. In a method for manufacturing a magnetoresistive effect magnetic head having magnetic domain control layers for magnetically applying a bias in the longitudinal direction to the magnetoresistive effect film, the magnetoresistive effect film having a predetermined shape. Immediately after patterning, the buffer layer and the magnetic domain control layer are continuously formed, patterned into a predetermined shape, and then heat-treated while applying a magnetic field in the easy axis direction of the magnetoresistive effect film. And manufacturing method of magnetoresistive effect magnetic head. 5. The heat treatment is performed at 260 ° C. to 300 ° C. for 60 hours.
The method of manufacturing a magnetoresistive effect magnetic head according to claim 4, wherein the heating is performed for 20 hours. 6. A group of a plurality of magnetic disks laminated on a spindle shaft, a motor for rotationally driving the spindle, a magnet and a voice coil constituting a voice coil motor for driving a carriage movement, and a base for supporting them. And a voice coil motor control circuit that controls the voice coil motor based on the signal sent from the host device, and the function of converting the data from the host device into a current flowing to the magnetic head according to the writing method, and the magnetic disk A write / read circuit having a function of converting data from a digital signal into a digital signal, wherein the write / read circuit is a magnetic disk device connected to the host device via an interface, and the magnetic head is , Magnetism that converts magnetic signals into electrical signals using the magnetoresistive effect An anti-effect film, a pair of electrodes for passing a signal detection current through the magneto-resistive film, and a magneto-resistive film disposed at both ends of the magneto-resistive film. A magnetic bias is applied to the magneto-resistive film in the longitudinal direction. A magnetic disk drive having a magnetic domain control layer for achieving the above, wherein a buffer layer made of a ferromagnetic film is provided between the magnetoresistive effect film and the magnetic domain control layer. 7. The magnetic disk drive according to claim 6, wherein the buffer layer formed of a ferromagnetic film of the magnetic head has a film thickness of 1 to 5 nm. 8. The magnetic disk device according to claim 6, wherein the buffer layer of the magnetic head is formed of a film made of the same material as the magnetic domain control layer. 9. The recording density of the recording medium of the magnetic magnetic head is 500 Mb / in ² or more.
The magnetic disk device according to 1.