CN112951875B - Magnetic random access memory and method of forming the same - Google Patents
Magnetic random access memory and method of forming the same Download PDFInfo
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B61/00—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
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- Mram Or Spin Memory Techniques (AREA)
Abstract
一种磁随机存取存储器及其形成方法，磁随机存取存储器包括：衬底；位于衬底上的第一介质层，所述第一介质层内具有第一开口；位于第一开口内的若干层复合层，若干层复合层沿垂直于第一开口侧壁表面和底部表面的方向重叠，且所述复合层包括第一电极层和位于第一电极层表面的第二电极层，所述第一电极层和第二电极层的材料不同；位于若干层复合层上的磁性隧道结构；位于磁性隧道结构上的顶部电极。所述磁随机存取存储器的性能得到提升。
A magnetic random access memory and a method for forming the same, the magnetic random access memory comprising: a substrate; a first dielectric layer located on the substrate, the first dielectric layer having a first opening; a plurality of composite layers located in the first opening, the plurality of composite layers overlapping in a direction perpendicular to the sidewall surface and the bottom surface of the first opening, and the composite layers comprising a first electrode layer and a second electrode layer located on the surface of the first electrode layer, the first electrode layer and the second electrode layer being made of different materials; a magnetic tunnel structure located on the plurality of composite layers; and a top electrode located on the magnetic tunnel structure. The performance of the magnetic random access memory is improved.
Description
Technical Field
The present disclosure relates to semiconductor manufacturing, and more particularly, to a magnetic random access memory and a method for forming the same.
Background
Magnetic random access memory is a non-volatile memory technology, and is being widely accepted in the industry as a mainstream data storage technology. It integrates a magnetoresistive device and a silicon-based selection matrix. Key attributes are non-volatility, low voltage operation, endurance for unlimited read and write, fast read and write operations, and ease of integration as a back-end technology. These characteristics make it possible to replace many types of memory in various applications with magnetic random access memory.
The magnetic random access memory stores "1", "0" data through a magnetic tunnel junction (Magnetic Tunnel Junctions, MTJ for short) element. The basic configuration of the magnetic tunnel junction element is a configuration in which an insulating layer (i.e., tunnel barrier) is sandwiched by two ferromagnetic layers. The data stored in the MTJ element is determined by whether the magnetization states of the two magnetic layers are parallel or antiparallel. In this case, parallel means that the magnetization directions of the two magnetic layers are the same, and antiparallel means that the magnetization directions of the two magnetic layers are opposite.
The performance of the existing magnetic random access memory is still to be improved.
Disclosure of Invention
The invention provides a magnetic random access memory and a forming method thereof, which are used for improving the performance of the magnetic random access memory.
In order to solve the technical problems, the technical scheme of the invention provides a magnetic random access memory, which comprises a substrate, a first dielectric layer, a plurality of composite layers, a magnetic tunnel structure and a top electrode, wherein the first dielectric layer is arranged on the substrate, the first dielectric layer is provided with a first opening, the composite layers are arranged in the first opening and overlap in the direction perpendicular to the side wall surface and the bottom surface of the first opening, the composite layers comprise a first electrode layer and a second electrode layer which is arranged on the surface of the first electrode layer, the materials of the first electrode layer and the second electrode layer are different, the magnetic tunnel structure is arranged on the composite layers, and the top electrode is arranged on the magnetic tunnel structure.
Optionally, the resistivity of the second electrode layer ranges from 60 mu omega cm to 100 mu omega cm, and the material of the second electrode layer comprises alpha-ta or titanium nitride.
Optionally, the material of the first electrode layer includes an amorphous conductive material, and the amorphous conductive material includes tantalum nitride or titanium nitride.
Optionally, the thickness of the plurality of composite layers in the first opening ranges from 20 angstroms to 1000 angstroms.
Optionally, the thickness of the first electrode layer ranges from 1 angstrom to 50 angstrom, and the thickness of the second electrode layer ranges from 1 angstrom to 50 angstrom.
Optionally, at least one first electrode layer of the plurality of composite layers further extends to a portion of the surface of the first dielectric layer.
Optionally, the substrate comprises a base and a device layer positioned on the base, the device layer comprises a device structure and a third dielectric layer surrounding the device structure, the device structure comprises a transistor, a resistor, an inductor, a capacitor or a conductive structure, and the composite layers are electrically connected with the substrate.
Optionally, the magnetic tunnel structure comprises a buffer layer, a fixed layer positioned on the buffer layer, an insulating layer positioned on the fixed layer, a free layer positioned on the insulating layer, and a cover layer positioned on the free layer.
Optionally, the material of the buffer layer includes ruthenium, cobalt or platinum, the material of the fixing layer includes a ferromagnetic material, the ferromagnetic material includes cobalt-iron-boron, cobalt-iron, nickel-iron or cobalt-iron-nickel, the material of the insulating layer includes magnesium oxide or aluminum oxide, the material of the free layer includes a ferromagnetic material, the ferromagnetic material includes cobalt-iron-boron, cobalt-iron, nickel-iron or cobalt-iron-nickel, and the material of the covering layer includes magnesium oxide, tantalum or tungsten.
Optionally, a stop layer is positioned on the side wall surface of the magnetic tunnel structure, the top surface of the top electrode and the side wall surface.
Optionally, the device further comprises an isolation structure positioned on the surface of the stop layer and a conductive plug positioned in the isolation structure, wherein the conductive plug is electrically connected with the top electrode.
Correspondingly, the technical scheme of the invention also provides a method for forming the magnetic random access memory, which comprises the steps of providing a substrate, forming a first dielectric layer on the substrate, forming a first opening in the first dielectric layer, forming a plurality of composite layers in the first opening, wherein the composite layers are overlapped along the direction perpendicular to the side wall surface and the bottom surface of the first opening, the composite layers comprise a first electrode layer and a second electrode layer positioned on the surface of the first electrode layer, forming a magnetic tunnel structure on the composite layers, and forming a top electrode on the magnetic tunnel structure.
Optionally, at least one first electrode layer of the plurality of composite layers further extends to a portion of a surface of the first dielectric layer.
Optionally, the forming method of the composite layers comprises the steps of forming a plurality of overlapped composite material layers on the bottom surface, the side wall surface and the first dielectric layer surface of the first opening, wherein each composite material layer comprises a first electrode material layer and a second electrode material layer positioned on the first electrode material layer, and flattening the composite material layers until the composite material layers positioned on the surface of the first dielectric layer reach a preset thickness range, and forming the composite layers in the first opening.
Optionally, the preset thickness of the composite material layer on the surface of the first dielectric layer ranges from 20 angstroms to 500 angstroms.
Optionally, the first electrode material layer and the second electrode material layer are repeated for a number of times ranging from 1 to 30.
Optionally, after forming the composite material layer and before flattening the composite material layer, forming a third electrode material layer on the surface of the composite material layer, wherein the material of the third electrode material layer is the same as that of the first electrode material layer.
Optionally, the process of planarizing the composite layer includes a chemical mechanical polishing process or an etch-back process.
Optionally, the method for forming the magnetic tunnel structure and the top electrode comprises the steps of forming a buffer material layer on the composite material layer, forming a fixed material layer on the buffer material layer, forming an insulating material layer on the fixed material layer, forming a free material layer on the insulating material layer, forming a covering material layer on the free material layer, forming a top electrode material layer on the covering material layer, forming a patterned mask layer on the top electrode material layer, wherein the patterned mask layer exposes part of the top surface of the top electrode material layer, and etching the top electrode material layer, the covering material layer, the free material layer, the insulating material layer, the fixed material layer, the buffer material layer and the composite material layer by taking the patterned mask layer as a mask until the surface of the first dielectric layer is exposed, so as to form the magnetic tunnel structure and the top electrode.
Optionally, after forming the top electrode, a stop layer is formed on the side wall surface of the magnetic tunnel structure, the top surface of the top electrode and the side wall surface, an isolation structure is formed on the surface of the stop layer, and a conductive plug is formed in the isolation structure and is electrically connected with the top electrode.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
The magnetic random access memory comprises a plurality of composite layers, wherein each composite layer comprises a first electrode layer and a second electrode layer, and on one hand, materials of the first electrode layer and materials of the second electrode layer are different, so that the composite layers are wider in material selection range, and materials with certain resistivity and diffusion barrier capability can be selected according to the performance requirements of devices. The material with low resistivity enables the read-write sensitivity of the magnetic random access memory to be low in error rate, and the material with good diffusion blocking capability can block the mutual diffusion of ions in the first dielectric layer and ions in the magnetic tunnel structure, so that the condition that the performance of the magnetic tunnel structure is invalid due to ion diffusion is avoided, and the service life of the magnetic random access memory is prolonged. On the other hand, the thickness of the composite layer is adjustable when the composite layer comprises a first electrode layer and a second electrode layer, so that the performance satisfaction degree of the magnetic random access memory is higher, the selection is larger, and the application prospect is wider.
Further, the resistivity of the material of the first electrode layer is lower, so that the magnetic random access memory has a higher tunneling magnetoresistance ratio, and the higher tunneling magnetoresistance ratio enables the read-write speed of the magnetic random access memory to be fast and is not prone to error.
Further, the material of the second electrode layer includes an amorphous conductive material, and the amorphous conductive material is in a long-range disordered molecular arrangement state, so that ions in the first dielectric layer and ions in the magnetic tunnel structure are not easy to diffuse mutually through the composite layer, and the situation that the ions in the first dielectric layer and the ions in the magnetic tunnel structure diffuse mutually to cause the functional failure of the magnetic tunnel structure is avoided, thereby prolonging the service life of the magnetic random access memory.
Further, the thickness range of the single-layer first electrode layer is 1 angstrom to 50 angstrom, the thickness range is smaller, the smaller thickness enables the first electrode layer to have lower resistivity, so that the resistivity of the composite layer is smaller, the performance of the magnetic random access memory is improved, the thickness range of the single-layer second electrode layer is 1 angstrom to 50 angstrom, the thickness range is smaller, the second electrode layer material in the thickness range is amorphous, so that the second electrode layer keeps better diffusion blocking capability, the diffusion blocking capability of the composite layer is better, and the performance of the magnetic random access memory is improved.
Drawings
FIG. 1 is a schematic cross-sectional view of a magnetic random access memory according to one embodiment;
fig. 2 to 9 are schematic cross-sectional views illustrating a process of forming a mram in accordance with an embodiment of the present invention.
Detailed Description
As described in the background, the performance of existing mram is still to be improved. The analysis will now be described with reference to specific examples.
FIG. 1 is a schematic cross-sectional view of a magnetic random access memory according to an embodiment.
Referring to fig. 1, the mram includes a substrate 100, a gate structure 102 on the substrate 100, source/drain doped regions 101 in the substrate on both sides of the gate structure 102, a first dielectric layer 103 on the substrate 100, a conductive structure 104 in the first dielectric layer 103, a second dielectric layer 105 on the first dielectric layer 103, a bottom electrode plug 106 in the second dielectric layer 105, the bottom electrode plug 106 being electrically connected to the conductive structure 104, a bottom electrode 107 on the bottom electrode plug 106 and the second dielectric layer 105, a magnetic tunnel structure 108 on the bottom electrode 107, a top electrode 109 on the magnetic tunnel structure 108, a sidewall structure 110 on a sidewall surface of the magnetic tunnel structure 108, a sidewall surface and a top surface of the top electrode 109, an isolation layer 111 on the sidewall structure 110, a third dielectric layer 112 on the isolation layer 111, a top electrode plug 113 in the third dielectric layer 112 and 111, the top electrode plug 113 being electrically connected to the top electrode 109.
In the mram structure, the bottom electrode 107 is electrically connected to the conductive structure 104 through a bottom electrode plug 106 located in the second dielectric layer 105, where the material of the bottom electrode 107 is a common conductive material, and the conductive material includes one or more combinations of tantalum nitride, titanium nitride, tantalum and titanium, and the material of the bottom electrode plug 106 is a common conductive material, and the conductive material includes one or more combinations of copper, tungsten, aluminum, titanium nitride, tantalum nitride and cobalt. However, as technology advances, the size of the mram is becoming smaller and smaller, and conventional bottom electrode and bottom electrode plug materials have not met the resistivity and diffusion barrier capability requirements, the mram needs to be improved so that the performance of the mram is met.
In order to solve the problems, the technical scheme of the invention provides a magnetic random access memory and a forming method thereof, wherein a composite layer of the magnetic random access memory comprises a plurality of first electrode layers and second electrode layers, materials of the first electrode layers and materials of the second electrode layers are different, and meanwhile, the plurality of first electrode layers and the plurality of second electrode layers are alternately arranged along the direction perpendicular to the surface of a substrate, so that the composite layer can have low resistivity and better diffusion blocking capability, the low resistivity of the composite layer enables the read-write sensitivity of the magnetic random access memory to be low, the error rate is low, and the better diffusion blocking capability of the composite layer can block the mutual diffusion of ions in a first dielectric layer and ions in a magnetic tunnel structure, thereby prolonging the service life of the magnetic random access memory and improving the performance of the magnetic random access memory.
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
Fig. 2 to 9 are schematic cross-sectional views illustrating a process of forming a mram in accordance with an embodiment of the present invention.
Referring to fig. 2, a substrate is provided.
The substrate includes a base 200 and a device layer on the base 200, the device layer including a device structure (not shown) including a transistor, a resistor, an inductor, a capacitor, or a conductive structure, and a third dielectric layer 201 surrounding the device structure.
In this embodiment, the device structure includes a transistor.
The material of the substrate 200 includes silicon, silicon germanium, silicon-on-insulator, or germanium-on-insulator. The material of the third dielectric layer 201 includes silicon oxide or silicon nitride.
In this embodiment, the material of the substrate 200 includes silicon. The material of the third dielectric layer 201 includes silicon oxide.
Referring to fig. 3, a first dielectric layer 202 is formed on the substrate, and a first opening 203 is formed in the first dielectric layer 202.
The method for forming the first opening 203 includes forming a dielectric material layer (not shown) on the substrate, planarizing the dielectric material layer to form a first dielectric layer 202, forming a patterned layer (not shown) on the first dielectric layer 202, wherein the patterned layer exposes a portion of the surface of the first dielectric layer 202, and etching the first dielectric layer 202 with the patterned layer as a mask until the surface of the substrate is exposed, thereby forming the first opening 203 in the first dielectric layer 202.
The material of the first dielectric layer 202 includes silicon oxide, silicon oxycarbide, silicon nitride or silicon oxynitride, the process of forming the dielectric material layer includes a chemical vapor deposition process, a physical vapor deposition process or an atomic layer deposition process, the process of planarizing the dielectric material layer includes a chemical mechanical polishing process or an etching back process, and the process of etching the first dielectric layer 202 includes a dry etching process or a wet etching process.
In this embodiment, the material of the first dielectric layer 202 includes silicon oxide, the process of forming the dielectric material layer includes a chemical vapor deposition process capable of rapidly forming a dielectric material layer with a dense structure and a thicker thickness, the process of planarizing the dielectric material layer includes a chemical mechanical polishing process, and the process of etching the first dielectric layer 202 includes a dry etching process.
The first opening 203 is used for forming a plurality of composite layers in the first opening 203 later, and the composite layers are electrically connected with the substrate exposed by the first opening 203.
The thickness of the first dielectric layer 202 ranges from 20 angstroms to 1000 angstroms.
Next, a plurality of composite layers are formed in the first opening 203, the composite layers overlap in a direction perpendicular to the sidewall surface and the bottom surface of the first opening 203, and the composite layers include a first electrode layer and a second electrode layer located on the surface of the first electrode layer.
In this embodiment, at least one first electrode layer of the plurality of composite layers further extends to a portion of the surface of the first dielectric layer 202.
Referring to fig. 4, a plurality of overlapped composite material layers are formed on the bottom surface, the sidewall surface and the surface of the first dielectric layer 202 of the first opening 203, and each composite material layer includes a first electrode material layer 204 and a second electrode material layer 205 disposed on the first electrode material layer 204.
The first electrode material layer 204 is used for forming a first electrode layer later, and the second electrode material layer 205 is used for forming a second electrode layer later.
The material of the first electrode material layer 204 comprises an amorphous conductive material, the amorphous conductive material comprises tantalum nitride or titanium nitride, the resistivity of the second electrode material layer 205 ranges from 60 mu omega cm to 100 mu omega cm, and the material of the second electrode layer comprises alpha-ta or titanium nitride.
The resistivity of the material of the first electrode material layer 204 is lower, so that the formed mram has a higher tunneling magnetoresistance ratio, and the higher tunneling magnetoresistance ratio makes the read/write speed of the mram fast and less prone to error.
The material of the second electrode material layer 205 includes an amorphous conductive material, where the amorphous conductive material is in a long-range disordered molecular arrangement state, so that ions in the first dielectric layer 202 and ions in a subsequently formed magnetic tunnel structure are not easy to diffuse mutually through the composite layer, and the situation that the ions in the first dielectric layer 202 and ions in the magnetic tunnel structure diffuse mutually to cause the functional failure of the magnetic tunnel structure is avoided, thereby improving the service life of the magnetic random access memory.
In this embodiment, the material of the first electrode material layer 204 includes tantalum nitride, and the material of the second electrode material layer 205 includes α -ta.
The process of forming the first electrode material layer 204 includes a chemical vapor deposition process or an atomic layer deposition process, and the process of forming the second electrode material layer 205 includes a physical vapor deposition process or an atomic layer deposition process.
In this embodiment, the process of forming the first electrode material layer 204 includes an atomic layer deposition process capable of forming the first electrode material layer 204 with a thin thickness, a compact structure and a uniform film thickness, and the process of forming the second electrode material layer 205 includes an atomic layer deposition process capable of forming the second electrode material layer 205 with a thin thickness, a compact structure and a uniform film thickness.
In this embodiment, the thickness of the single layer of the first electrode material layer 204 ranges from 1 angstrom to 50 angstrom, the thickness of the single layer of the second electrode material layer 205 ranges from 1 angstrom to 50 angstrom, and the number of times of repeating the first electrode material layer 204 and the second electrode material layer 205 ranges from 1 to 30.
The thickness of the single-layer first electrode material layer 204 ranges from 1 angstrom to 50 angstrom, the thickness range is smaller, the smaller thickness enables the first electrode layer to have lower resistivity, so that the resistivity of the composite layer is smaller, the performance of the magnetic random access memory is improved, the thickness range of the single-layer second electrode material layer 205 ranges from 1 angstrom to 50 angstrom, the thickness range is smaller, the second electrode layer material in the thickness range is amorphous, so that the second electrode layer keeps better diffusion blocking capability, the diffusion blocking capability of the composite layer is better, and the performance of the magnetic random access memory is improved.
With continued reference to fig. 4, after forming a plurality of overlapped composite material layers, a third electrode material layer 206 is formed on the surface of the composite material layer, where the material of the third electrode material layer 206 is the same as the material of the first electrode material layer 204.
The third electrode material layer 206 is used to compensate for the total thickness of the composite material layer, so that a composite layer of a predetermined thickness can be formed on the first dielectric layer 202 after the composite material layer is subsequently planarized.
In other embodiments, the third electrode material layer 206 can be omitted.
The material of the third electrode material layer 206 is the same as the material of the first electrode material layer 204, and the forming process of the third electrode material layer 206 is also the same as the forming process of the first electrode material layer 204, which is not described herein.
Referring to fig. 5, the composite layer is planarized until the composite layer on the surface of the first dielectric layer 202 reaches a preset thickness range, and the plurality of composite layers are formed in the first opening 203, where the composite layers include a first electrode layer 304 and a second electrode layer 305 on the first electrode layer 304.
At least one first electrode material layer 204 of the plurality of composite material layers is also located on the surface of the first dielectric layer 202. At least one first electrode material layer 204 located on the surface of the first dielectric layer 202, so that a subsequently formed composite layer also extends to a part of the surface of the first dielectric layer 202, so that the contact area between the composite layer and a subsequently formed magnetic tunnel structure is increased, and the magnetic tunnel structure can be driven better when an electric field is applied to the magnetic tunnel structure.
The composite material layer on the surface of the first dielectric layer 202 has a preset thickness ranging from 20 angstrom to 500 angstrom.
The thickness of the composite layers in the first opening 203 ranges from 20 angstroms to 1000 angstroms.
The process of planarizing the composite layer includes a chemical mechanical polishing process or an etch back process. In this embodiment, the process of planarizing the composite layer includes a chemical mechanical polishing process that is capable of planarizing the composite layer to a predetermined location quickly and accurately.
Next, a magnetic tunnel structure is formed over the number of composite layers, and a top electrode is formed over the magnetic tunnel structure. The magnetic tunnel structure comprises a buffer layer, a fixed layer positioned on the buffer layer, an insulating layer positioned on the fixed layer, a free layer positioned on the insulating layer and a covering layer positioned on the free layer.
Referring to fig. 6, a buffer material layer 207 is formed on the composite material layer, a fixing material layer 208 is formed on the buffer material layer 207, an insulating material layer 209 is formed on the fixing material layer 208, a free material layer 210 is formed on the insulating material layer 209, a cover material layer 211 is formed on the free material layer 210, a top electrode material layer 212 is formed on the cover material layer 211, and a patterned mask layer 213 is formed on the top electrode material layer 212, wherein the patterned mask layer 213 exposes a portion of the top surface of the top electrode material layer 212.
The buffer material layer 207 is a buffer layer providing material layer, the fixing material layer 208 is a fixing layer providing material layer, the insulating material layer 209 is an insulating layer providing material layer, the free material layer 210 is a free layer providing material layer, the covering material layer 211 is a covering layer providing material layer, and the top electrode material layer 212 is a top electrode forming material layer.
The material of the buffer material layer 207 includes ruthenium, cobalt or platinum, the material of the fixed material layer 208 includes a ferromagnetic material including cobalt-iron-boron, cobalt-iron, nickel-iron or cobalt-iron-nickel, the material of the insulating material layer 209 includes magnesium oxide or aluminum oxide, the material of the free material layer 210 includes a ferromagnetic material including cobalt-iron-boron, cobalt-iron, nickel-iron or cobalt-iron-nickel, the material of the cover material layer 211 includes magnesium oxide, tantalum or tungsten, the material of the top electrode material layer 212 includes a metal including tantalum nitride, titanium nitride, tantalum or titanium, and the material of the patterned mask layer 213 includes a photoresist or hard mask material including silicon oxide or silicon nitride.
In this embodiment, the material of the buffer material layer 207 includes ruthenium, the material of the fixed material layer 208 includes cobalt-iron-boron, the material of the insulating material layer 209 includes magnesium oxide, the material of the free material layer 210 includes cobalt-iron-boron, the material of the cover material layer 211 includes magnesium oxide, the material of the top electrode material layer 212 includes tantalum nitride, and the material of the patterned mask layer 213 includes photoresist.
Referring to fig. 7, the patterned mask layer 213 is used as a mask to etch the top electrode material layer 212, the covering material layer 211, the free material layer 210, the insulating material layer 209, the fixed material layer 208, the buffer material layer 207 and the composite material layer until the surface of the first dielectric layer 202 is exposed, so as to form the magnetic tunnel structure and the top electrode 312.
The magnetic tunnel structure includes a buffer layer 307, a fixed layer 308 on the buffer layer 307, an insulating layer 309 on the fixed layer 308, a free layer 310 on the insulating layer 309, and a capping layer 311 on the free layer 310.
At this time, at least one first electrode layer 304 of the plurality of composite layers extends to a portion of the surface of the first dielectric layer 202, so that the contact area between the composite layer and the formed magnetic tunnel structure is increased, and the magnetic tunnel structure can be driven better when an electric field is applied to the magnetic tunnel structure.
The process of etching the top electrode material layer 212, the capping material layer 211, the free material layer 210, the insulating material layer 209, the fixed material layer 208, the buffer material layer 207, and the composite material layer includes a dry etching process or a wet etching process.
In this embodiment, the processes of etching the top electrode material layer 212, the covering material layer 211, the free material layer 210, the insulating material layer 209, the fixed material layer 208, the buffer material layer 207 and the composite material layer include a dry etching process, and the dry etching process can form a magnetic tunnel structure with a better sidewall morphology.
After the magnetic tunnel structure is formed, the process of removing the patterned mask layer 213 includes an ashing process.
Referring to fig. 8, a stop layer 214 is formed on the magnetic tunnel structure sidewall surface, the top surface of the top electrode 312, and the sidewall surface.
The stop layer 214 is also located on sidewall surfaces of the number of composite layers that extend to a portion of the surface of the first dielectric layer 202.
The stop layer 214 is used as an etch stop layer for subsequent formation of conductive plugs on the top electrode 312. The formation process of the stop layer 214 includes an atomic layer deposition process or a chemical vapor deposition process, and the material of the stop layer 214 includes silicon nitride, silicon carbide, or silicon carbide nitride.
In this embodiment, the formation process of the stop layer 214 includes an atomic layer deposition process, and the material of the stop layer 214 includes silicon nitride.
Referring to fig. 9, an isolation structure 215 is formed on the surface of the stop layer 214, and a conductive plug 216 is formed in the isolation structure 215, wherein the conductive plug 216 is electrically connected with the top electrode 312.
The isolation structure 215 is formed from a material including silicon oxide, silicon oxycarbide, silicon nitride, or silicon oxynitride, and the isolation structure 215 is formed by a chemical vapor deposition process, a physical vapor deposition process, or an atomic layer deposition process.
In this embodiment, the material of the isolation structure 215 comprises silicon oxide, and the process of forming the isolation structure 215 comprises a chemical vapor deposition process capable of rapidly forming the isolation structure 215 with dense structure and thicker thickness.
The method for forming the conductive plug 216 includes forming a mask layer (not shown) on the surface of the isolation structure 215, the mask layer exposing a portion of the surface of the isolation structure 215, etching the isolation structure 215 and the stop layer 214 with the mask layer as a mask until the surface of the top electrode 312 is exposed, forming a second opening (not shown) in the isolation structure 215, forming a conductive plug material layer (not shown) in the second opening and on the surface of the isolation structure 215, and planarizing the conductive plug material layer until the surface of the isolation structure 215 is exposed, thereby forming the conductive plug 216.
The conductive plugs 216 are used to electrically connect the mram to an external device or conductive structure. The material of the conductive plug 216 includes one or more of copper, tungsten, titanium, and titanium nitride, the process of forming the conductive plug material layer includes a physical vapor deposition process, a chemical vapor deposition process, or an electroplating process, the process of etching the isolation structure 215 and the stop layer 214 includes a dry etching process or a wet etching process, and the process of planarizing the conductive plug material layer includes a chemical mechanical polishing process or an etching back process.
In this embodiment, the material of the conductive plugs 216 includes copper, the process of forming the conductive plug material layer includes a physical vapor deposition process, the process of etching the isolation structures 215 and the stop layer 214 includes a dry etching process, and the process of planarizing the conductive plug material layer includes a chemical mechanical polishing process.
The magnetic random access memory comprises a plurality of layers of composite layers, wherein each composite layer comprises a first electrode layer and a second electrode layer, and on one hand, materials of the first electrode layer and materials of the second electrode layer are different, so that the composite layers are wider in material selection range, and materials with certain resistivity and diffusion barrier capability can be selected according to the performance requirements of devices. The material with low resistivity enables the read-write sensitivity of the magnetic random access memory to be low in error rate, and the material with good diffusion blocking capability can block the mutual diffusion of ions in the first dielectric layer and ions in the magnetic tunnel structure, so that the condition that the performance of the magnetic tunnel structure is invalid due to ion diffusion is avoided, and the service life of the magnetic random access memory is prolonged. On the other hand, the thickness of the composite layer is adjustable when the composite layer comprises a first electrode layer and a second electrode layer, so that the performance satisfaction degree of the magnetic random access memory is higher, the selection is larger, and the application prospect is wider.
Correspondingly, the embodiment of the invention also provides a magnetic random access memory formed by adopting the method, please continue to refer to fig. 9, which includes:
A substrate;
A first dielectric layer 202 on the substrate, wherein a first opening is formed in the first dielectric layer 202;
A plurality of composite layers positioned in the first opening, wherein the composite layers are overlapped along the direction perpendicular to the side wall surface and the bottom surface of the first opening, the composite layers comprise a first electrode layer 304 and a second electrode layer 305 positioned on the surface of the first electrode layer 304, the materials of the first electrode layer 304 and the second electrode layer 305 are different, and at least one first electrode layer 304 in the composite layers also extends to part of the surface of the first dielectric layer 202;
a magnetic tunnel structure on the plurality of composite layers;
A top electrode 312 located on the magnetic tunnel structure;
A stop layer 214 on the side wall surface of the magnetic tunnel structure, the top surface of the top electrode 312 and the side wall surface, an isolation structure 215 on the surface of the stop layer 214, and a conductive plug 216 in the isolation structure 215, the conductive plug 216 being electrically connected to the top electrode 312.
The material of the first electrode layer comprises an amorphous conductive material, the amorphous conductive material comprises tantalum nitride or titanium nitride, the resistivity of the second electrode material layer 205 ranges from 60 mu omega cm to 100 mu omega cm, and the material of the second electrode layer comprises alpha-ta or titanium nitride.
The thickness range of the composite layers in the first opening is 20-1000 angstroms.
The thickness of the composite layer on a portion of the surface of the first dielectric layer 202 ranges from 20 a to 500 a.
The magnetic tunnel structure includes a buffer layer 307, a fixed layer 308 on the buffer layer 307, an insulating layer 309 on the fixed layer 308, a free layer 310 on the insulating layer 309, and a capping layer 311 on the free layer 310.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.
Claims (20)
1. A magnetic random access memory, comprising:
A substrate;
The first dielectric layer is positioned on the substrate and is provided with a first opening;
The composite layers are arranged in the first opening and overlap in a direction perpendicular to the side wall surface and the bottom surface of the first opening, the composite layers comprise a first electrode layer and a second electrode layer arranged on the surface of the first electrode layer, the materials of the first electrode layer and the second electrode layer are different, the material of the first electrode layer comprises an amorphous conductive material, and the resistivity of the second electrode layer ranges from 60 mu omega cm to 100 mu omega cm;
a magnetic tunnel structure on the plurality of composite layers;
a top electrode located on the magnetic tunnel structure.
2. The mram of claim 1, wherein a material of the second electrode layer comprises alpha-ta or titanium nitride.
3. The mram of claim 1, wherein the amorphous conductive material comprises tantalum nitride or titanium nitride.
4. The mram of claim 1, wherein the plurality of composite layers within the first opening have a thickness in a range of 20 angstroms to 1000 angstroms.
5. The mram of claim 4, wherein a thickness of the first electrode layer is in a range of 1 angstrom to 50 angstrom, and a thickness of the second electrode layer is in a range of 1 angstrom to 50 angstrom.
6. The mram of claim 1, wherein at least one of the plurality of composite layers further extends to a portion of a surface of the first dielectric layer.
7. The magnetic random access memory of claim 1 wherein the substrate includes a base and a device layer on the base, the device layer including a device structure and a third dielectric layer surrounding the device structure, the device structure including a transistor, a resistor, an inductor, a capacitor, or a conductive structure, the plurality of composite layers being electrically connected to the substrate.
8. The magnetic random access memory of claim 1 wherein the magnetic tunnel structure includes a buffer layer, a fixed layer on the buffer layer, an insulating layer on the fixed layer, a free layer on the insulating layer, and a capping layer on the free layer.
9. The mram of claim 8, wherein the material of the buffer layer comprises ruthenium, cobalt, or platinum, the material of the fixed layer comprises a ferromagnetic material comprising cobalt-iron-boron, cobalt-iron, nickel-iron, or cobalt-iron-nickel, the material of the insulating layer comprises magnesium oxide or aluminum oxide, the material of the free layer comprises a ferromagnetic material comprising cobalt-iron-boron, cobalt-iron, nickel-iron, or cobalt-iron-nickel, and the material of the cap layer comprises magnesium oxide, tantalum, or tungsten.
10. The magnetic random access memory of claim 1 further comprising a stop layer on a sidewall surface of the magnetic tunnel structure, a top surface of the top electrode, and a sidewall surface.
11. The MRAM as claimed in claim 10, further comprising an isolation structure on a surface of the stop layer, and a conductive plug in the isolation structure, the conductive plug being electrically connected to the top electrode.
12. A method of forming a magnetic random access memory as claimed in any one of claims 1 to 11, comprising:
providing a substrate;
Forming a first dielectric layer on a substrate, wherein a first opening is formed in the first dielectric layer;
forming a plurality of composite layers in the first opening, wherein the composite layers are overlapped along the direction perpendicular to the side wall surface and the bottom surface of the first opening, and the composite layers comprise a first electrode layer and a second electrode layer positioned on the surface of the first electrode layer;
forming a magnetic tunnel structure on the plurality of composite layers;
A top electrode is formed over the magnetic tunnel structure.
13. The method of claim 12, wherein at least one of the plurality of composite layers further extends to a portion of the surface of the first dielectric layer.
14. The method of claim 13, wherein forming a plurality of composite layers includes forming a plurality of overlapped composite layers on a bottom surface, a sidewall surface, and a first dielectric layer surface of the first opening, each composite layer including a first electrode material layer and a second electrode material layer on the first electrode material layer, planarizing the composite layers until the composite layers on the first dielectric layer surface reach a predetermined thickness range, and forming the plurality of composite layers in the first opening.
15. The method of claim 14, wherein the predetermined thickness of the composite layer on the surface of the first dielectric layer is in a range of 20 angstrom to 500 angstrom.
16. The method of claim 14, wherein the first electrode material layer and the second electrode material layer are repeated a number of times ranging from 1 to 30.
17. The method of claim 14, further comprising forming a third electrode material layer on a surface of the composite material layer after forming the composite material layer and before planarizing the composite material layer, wherein the third electrode material layer is the same material as the first electrode material layer.
18. The method of claim 14, wherein planarizing the composite layer comprises a chemical mechanical polishing process or an etch-back process.
19. The method of claim 14, wherein forming the magnetic tunnel structure and the top electrode comprises forming a buffer material layer over the composite material layer, forming a fixed material layer over the buffer material layer, forming an insulating material layer over the fixed material layer, forming a free material layer over the insulating material layer, forming a capping material layer over the free material layer, forming a top electrode material layer over the capping material layer, forming a patterned mask layer over the top electrode material layer, the patterned mask layer exposing a portion of a top surface of the top electrode material layer, and masking the top electrode material layer, capping material layer, free material layer, insulating material layer, fixed material layer, buffer material layer, and composite material layer with the patterned mask layer as a mask until the first dielectric layer surface is exposed, forming the magnetic tunnel structure and the top electrode.
20. The method of claim 13, further comprising forming a stop layer on a sidewall surface of the magnetic tunnel structure, a top surface of the top electrode, and a sidewall surface, forming an isolation structure on the stop layer surface, and forming a conductive plug in the isolation structure, the conductive plug electrically connected to the top electrode.
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| JP2001168418A (en) * | 1999-12-13 | 2001-06-22 | Rohm Co Ltd | Device using ferromagnetic tunnel junction element, and method of manufacturing the same |
| CN104218150A (en) * | 2013-06-05 | 2014-12-17 | 中芯国际集成电路制造(上海)有限公司 | Forming method of magnetic random access memory unit |
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| US6952364B2 (en) * | 2003-03-03 | 2005-10-04 | Samsung Electronics Co., Ltd. | Magnetic tunnel junction structures and methods of fabrication |
| KR20080061765A (en) * | 2006-12-28 | 2008-07-03 | 삼성전자주식회사 | MRAM-PRMA composite memory device and method of manufacturing the same |
| JP2010278074A (en) * | 2009-05-26 | 2010-12-09 | Fujitsu Semiconductor Ltd | Electronic device and manufacturing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2001168418A (en) * | 1999-12-13 | 2001-06-22 | Rohm Co Ltd | Device using ferromagnetic tunnel junction element, and method of manufacturing the same |
| CN104218150A (en) * | 2013-06-05 | 2014-12-17 | 中芯国际集成电路制造(上海)有限公司 | Forming method of magnetic random access memory unit |
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