Magnetic random access memory and method of forming the same

Abstract

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

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a magnetic random access memory and a forming method thereof. Background Art

[0002] Magnetic random access memory is a non-volatile memory technology that is being widely accepted by 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, unlimited read and write endurance, fast read and write operations, and easy integration as a back-end technology. These characteristics make magnetic random access memory a potential replacement for many types of memory in various applications.

[0003] Magnetic random access memory stores "1" and "0" data through magnetic tunnel junction (MTJ) elements. The basic structure of a magnetic tunnel junction element is a structure in which an insulating layer (i.e., a tunnel barrier) is sandwiched between two strong magnetic 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.

[0004] The performance of existing magnetic random access memory needs to be improved. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a magnetic random access memory and a forming method thereof, so as to improve the performance of the magnetic random access memory.

[0006] To solve the above technical problems, the technical solution of the present invention provides a 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 side wall 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.

[0007] Optionally, the resistivity range of the second electrode layer is 60 μΩ·cm to 100 μΩ·cm; and the material of the second electrode layer includes α-ta or titanium nitride.

[0008] Optionally, the material of the first electrode layer includes an amorphous conductive material, and the amorphous conductive material includes tantalum nitride or titanium nitride.

[0009] Optionally, the thickness of the plurality of composite layers in the first opening ranges from 20 angstroms to 1000 angstroms.

[0010] Optionally, the thickness of a single layer of the first electrode layer ranges from 1 angstrom to 50 angstroms; the thickness of a single layer of the second electrode layer ranges from 1 angstrom to 50 angstroms.

[0011] Optionally, at least one first electrode layer among the plurality of composite layers further extends to a portion of the surface of the first dielectric layer.

[0012] Optionally, the substrate includes: a base and a device layer located on the base; the device layer includes a device structure and a third dielectric layer surrounding the device structure, the device structure includes a transistor, a resistor, an inductor, a capacitor or a conductive structure; the plurality of composite layers are electrically connected to the substrate.

[0013] Optionally, the magnetic tunnel structure includes: a buffer layer; a fixed layer located on the buffer layer; an insulating layer located on the fixed layer; a free layer located on the insulating layer; and a covering layer located on the free layer.

[0014] Optionally, the material of the buffer layer includes ruthenium, cobalt or platinum; the material of the fixed layer includes ferromagnetic material, and 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 ferromagnetic material, and the ferromagnetic material includes cobalt iron boron, cobalt iron, nickel iron or cobalt iron nickel; the material of the covering layer includes magnesium oxide, tantalum or tungsten.

[0015] Optionally, it also includes: a stop layer located on the side wall surface of the magnetic tunnel structure, the top surface of the top electrode and the side wall surface.

[0016] Optionally, the method further includes: an isolation structure located on the surface of the stop layer; and a conductive plug located in the isolation structure, wherein the conductive plug is electrically connected to the top electrode.

[0017] Correspondingly, the technical solution of the present invention also provides a method for forming any of the above-mentioned magnetic random access memory, comprising: providing a substrate; forming a first dielectric layer on the substrate, wherein the first dielectric layer has a first opening; forming a plurality of composite layers in the first opening, wherein the plurality of composite layers overlap in a direction perpendicular to the side wall surface and the bottom surface of the first opening, and the composite layers include a first electrode layer and a second electrode layer located on the surface of the first electrode layer; forming a magnetic tunnel structure on the plurality of composite layers; and forming a top electrode on the magnetic tunnel structure.

[0018] Optionally, at least one first electrode layer among the plurality of composite layers further extends to a portion of the surface of the first dielectric layer.

[0019] Optionally, the method for forming the several layers of composite layers includes: forming several overlapping composite material layers on the bottom surface, side wall surface and first dielectric layer surface of the first opening, each composite material layer including a first electrode material layer and a second electrode material layer located on the first electrode material layer; flattening the composite material layers until the composite material layer located on the surface of the first dielectric layer reaches a preset thickness range, thereby forming the several layers of composite layers in the first opening.

[0020] Optionally, the preset thickness range of the composite material layer located on the surface of the first dielectric layer is 20 angstroms to 500 angstroms.

[0021] Optionally, the number of times of repeating the first electrode material layer and the second electrode material layer ranges from 1 to 30.

[0022] Optionally, after forming the composite material layer and before planarizing the composite material layer, the method further includes: 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.

[0023] Optionally, the process of planarizing the composite material layer includes a chemical mechanical polishing process or an etch-back process.

[0024] Optionally, the method for forming the magnetic tunnel structure and the top electrode includes: 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, the patterned mask layer exposing a portion of the top surface of the top electrode material layer; 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 using the patterned mask layer as a mask until the surface of the first dielectric layer is exposed to form the magnetic tunnel structure and the top electrode.

[0025] Optionally, after forming the top electrode, the method further includes: forming a stop layer on the side wall surface of the magnetic tunnel structure, the top surface of the top electrode and the side wall surface; forming an isolation structure on the surface of the stop layer; and forming a conductive plug in the isolation structure, wherein the conductive plug is electrically connected to the top electrode.

[0026] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0027] The several composite layers in the magnetic random access memory include a first electrode layer and a second electrode layer. On the one hand, the material of the first electrode layer is different from the material of the second electrode layer, so that the material selection range of the composite layer is wider, and materials with certain resistivity and diffusion barrier capabilities can be selected according to the performance requirements of the device. Among them, the material with low resistivity makes the reading and writing of the magnetic random access memory sensitive and the error rate is small; the material with good diffusion barrier capability can block the mutual diffusion of ions in the first dielectric layer and ions in the magnetic tunnel structure, avoiding the failure of the performance of the magnetic tunnel structure caused by ion diffusion, thereby improving the service life of the magnetic random access memory. On the other hand, the composite layer includes the first electrode layer and the second electrode layer, and the thickness of the composite layer is adjustable, so that the performance satisfaction of the magnetic random access memory is higher, the selection is larger, and the application prospect is broader.

[0028] Furthermore, the resistivity of the material of the first electrode layer is relatively low, so that the magnetic random access memory has a relatively high tunneling magnetoresistance ratio. The relatively high tunneling magnetoresistance ratio enables the magnetic random access memory to have a fast reading and writing speed and be less prone to errors.

[0029] Furthermore, 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 the ions in the first dielectric layer and the ions in the magnetic tunnel structure are not easy to diffuse through the composite layer, thereby avoiding the mutual diffusion of ions in the first dielectric layer and the ions in the magnetic tunnel structure to cause functional failure of the magnetic tunnel structure, thereby improving the service life of the magnetic random access memory.

[0030] Furthermore, the thickness range of the single-layer first electrode layer is 1 angstrom to 50 angstroms, and the thickness range is relatively small. The smaller thickness makes the first electrode layer have a lower resistivity, thereby making the resistivity of the composite layer smaller, which is beneficial to the performance improvement of the magnetic random access memory; the thickness range of the single-layer second electrode layer is 1 angstrom to 50 angstroms, and the thickness range is relatively small. The second electrode layer material within this thickness range is amorphous, thereby making the second electrode layer maintain a good diffusion barrier ability, thereby making the diffusion barrier ability of the composite layer better, which is beneficial to the performance improvement of the magnetic random access memory. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic cross-sectional structural diagram of a magnetic random access memory in one embodiment;

[0032] Figures 2 to 9 It is a schematic cross-sectional structure diagram of the formation process of the magnetic random access memory in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] As described in the background art, the performance of existing magnetic random access memory needs to be improved. Now, an analysis and description will be given in conjunction with a specific embodiment.

[0034] Figure 1 It is a schematic diagram of the cross-sectional structure of a magnetic random access memory in one embodiment.

[0035] Please refer to Figure 1 The magnetic random access memory comprises: a substrate 100; a gate structure 102 located on the substrate 100; a source-drain doped region 101 located in the substrate on both sides of the gate structure 102; a first dielectric layer 103 located on the substrate 100; a conductive structure 104 located in the first dielectric layer 103; a second dielectric layer 105 located on the first dielectric layer 103; a bottom electrode plug 106 located in the second dielectric layer 105, the bottom electrode plug 106 being electrically connected to the conductive structure 104; a bottom electrode plug 106 located on the bottom electrode plug 106 and the second dielectric layer 105 Electrode 107; a magnetic tunnel structure 108 located on the bottom electrode 107; a top electrode 109 located on the magnetic tunnel structure 108; a sidewall structure 110 located on the sidewall surface of the magnetic tunnel structure 108, the sidewall surface of the bottom electrode 107, and the sidewall surface and top surface of the top electrode 109; an isolation layer 111 located on the sidewall structure 110; a third dielectric layer 112 located on the isolation layer 111; a top electrode plug 113 located in the third dielectric layer 112 and the isolation layer 111, and the top electrode plug 113 is electrically connected to the top electrode 109.

[0036] In the structure of the magnetic random access memory, the bottom electrode 107 is electrically connected to the conductive structure 104 through the bottom electrode plug 106 located in the second dielectric layer 105. 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; 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, tantalum nitride and cobalt. However, with the advancement of technology, the size of the magnetic random access memory is getting smaller and smaller, and the materials of the conventional bottom electrode and bottom electrode plug no longer meet the requirements of resistivity and diffusion barrier capability. Therefore, the magnetic random access memory needs to be improved so that the performance of the magnetic random access memory is met.

[0037] In order to solve the above problems, the technical solution of the present invention provides a magnetic random access memory and a method for forming the same. The composite layer of the magnetic random access memory includes a plurality of first electrode layers and a second electrode layer. The material of the first electrode layer is different from that of the second electrode layer. At the same time, the plurality of first electrode layers and the second electrode layers are alternately arranged in a direction perpendicular to the surface of the substrate, so that the composite layer can have both low resistivity and good diffusion barrier ability. The low resistivity of the composite layer makes the reading and writing of the magnetic random access memory sensitive and the error rate low; the good diffusion barrier ability of the composite layer can prevent the ions in the first dielectric layer and the ions in the magnetic tunnel structure from diffusing with each other, thereby improving the service life of the magnetic random access memory and improving the performance of the magnetic random access memory.

[0038] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0039] Figures 2 to 9 It is a schematic cross-sectional structure diagram of the formation process of the magnetic random access memory in an embodiment of the present invention.

[0040] Please refer to Figure 2 , providing a substrate.

[0041] The substrate includes: a base 200 and a device layer located on the base 200; the device layer includes a device structure (not shown) and a third dielectric layer 201 surrounding the device structure, and the device structure includes a transistor, a resistor, an inductor, a capacitor or a conductive structure.

[0042] In this embodiment, the device structure includes a transistor.

[0043] The material of the substrate 200 includes silicon, silicon germanium, germanium, silicon on insulator or germanium on insulator. The material of the third dielectric layer 201 includes silicon oxide or silicon nitride.

[0044] In this embodiment, the material of the substrate 200 includes silicon. The material of the third dielectric layer 201 includes silicon oxide.

[0045] Please refer to Figure 3 A first dielectric layer 202 is formed on the substrate, and a first opening 203 is formed in the first dielectric layer 202.

[0046] 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; etching the first dielectric layer 202 using the patterned layer as a mask until the substrate surface is exposed, thereby forming a first opening 203 in the first dielectric layer 202.

[0047] The material of the first dielectric layer 202 includes silicon oxide, silicon oxycarbide, carbon silicon oxyhydride, 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 a back etching process; the process of etching the first dielectric layer 202 includes a dry etching process or a wet etching process.

[0048] 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, and the chemical vapor deposition process can quickly form a dielectric material layer with a dense structure and a thick 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.

[0049] The first opening 203 is used to subsequently form a plurality of composite layers in the first opening 203 , and the plurality of composite layers are electrically connected to the substrate exposed by the first opening 203 .

[0050] The thickness of the first dielectric layer 202 ranges from 20 angstroms to 1000 angstroms.

[0051] Next, several 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 . The composite layers include a first electrode layer and a second electrode layer located on the surface of the first electrode layer.

[0052] In this embodiment, at least one first electrode layer among the plurality of composite layers further extends to a portion of the surface of the first dielectric layer 202 .

[0053] Please refer to Figure 4 Several overlapping composite material layers are formed on the bottom surface, side wall surface and surface of the first dielectric layer 202 of the first opening 203 , each composite material layer includes a first electrode material layer 204 and a second electrode material layer 205 located on the first electrode material layer 204 .

[0054] The first electrode material layer 204 is used to subsequently form a first electrode layer; the second electrode material layer 205 is used to subsequently form a second electrode layer.

[0055] The material of the first electrode material layer 204 includes an amorphous conductive material, and the amorphous conductive material includes tantalum nitride or titanium nitride; the resistivity range of the second electrode material layer 205 is: 60μΩ·cm~100μΩ·cm, and the material includes the material of the second electrode layer including α-ta or titanium nitride.

[0056] The resistivity of the material of the first electrode material layer 204 is relatively low, so that the formed magnetic random access memory has a relatively high tunneling magnetoresistance ratio. The relatively high tunneling magnetoresistance ratio enables the magnetic random access memory to have a fast reading and writing speed and be less prone to errors.

[0057] The material of the second electrode material layer 205 includes an amorphous conductive material, which is in a long-range disordered molecular arrangement state, so that the ions in the first dielectric layer 202 and the ions in the subsequently formed magnetic tunnel structure are not easy to diffuse through the composite layer, thereby avoiding the mutual diffusion of ions in the first dielectric layer 202 and ions in the magnetic tunnel structure and causing functional failure of the magnetic tunnel structure, thereby improving the service life of the magnetic random access memory.

[0058] In this embodiment, the material of the first electrode material layer 204 includes tantalum nitride; the material of the second electrode material layer 205 includes α-ta.

[0059] The process of forming the first electrode material layer 204 includes a chemical vapor deposition process or an atomic layer deposition process; the process of forming the second electrode material layer 205 includes a physical vapor deposition process or an atomic layer deposition process.

[0060] In this embodiment, the process for forming the first electrode material layer 204 includes an atomic layer deposition process, which can form a first electrode material layer 204 with a thin thickness, a dense structure and a uniform film thickness; the process for forming the second electrode material layer 205 includes an atomic layer deposition process, which can form a second electrode material layer 205 with a thin thickness, a dense structure and a uniform film thickness.

[0061] In this embodiment, the thickness of a single layer of the first electrode material layer 204 ranges from 1 angstrom to 50 angstroms; the thickness of a single layer of the second electrode material layer 205 ranges from 1 angstrom to 50 angstroms; and the number of times the first electrode material layer 204 and the second electrode material layer 205 are repeated ranges from 1 to 30.

[0062] The thickness range of the single-layer first electrode material layer 204 is 1 angstrom to 50 angstroms, and the thickness range is relatively small. The smaller thickness makes the first electrode layer have a lower resistivity, thereby making the resistivity of the composite layer smaller, which is beneficial to the performance improvement of the magnetic random access memory; the thickness range of the single-layer second electrode material layer 205 is 1 angstrom to 50 angstroms, and the thickness range is relatively small. The second electrode layer material within this thickness range is amorphous, thereby making the second electrode layer maintain a good diffusion barrier ability, thereby making the diffusion barrier ability of the composite layer better, which is beneficial to the performance improvement of the magnetic random access memory.

[0063] Please continue to refer to Figure 4 After forming several overlapping composite material layers, a third electrode material layer 206 is formed on the surface of the composite material layer. The material of the third electrode material layer 206 is the same as that of the first electrode material layer 204 .

[0064] The third electrode material layer 206 is used to compensate for the total thickness of the composite material layer, so that after the composite material layer is subsequently planarized, a composite layer with a preset thickness can be formed on the first dielectric layer 202 .

[0065] In other embodiments, the third electrode material layer 206 may not be formed.

[0066] The material of the third electrode material layer 206 is the same as that of the first electrode material layer 204 , and the formation process of the third electrode material layer 206 is also the same as that of the first electrode material layer 204 , which will not be described in detail herein.

[0067] Please refer to Figure 5 , flattening the composite material layer until the composite material layer located on the surface of the first dielectric layer 202 reaches a preset thickness range, and forming the plurality of composite layers in the first opening 203 , wherein the composite layer includes a first electrode layer 304 and a second electrode layer 305 located on the first electrode layer 304 .

[0068] At least one first electrode material layer 204 among the plurality of composite material layers is also located on the surface of the first dielectric layer 202. The at least one first electrode material layer 204 located on the surface of the first dielectric layer 202 allows the subsequently formed composite layer to extend to a portion of the surface of the first dielectric layer 202, thereby increasing the contact area between the composite layer and the subsequently formed magnetic tunnel structure, and when an electric field is applied to the magnetic tunnel structure, the magnetic tunnel structure can be better driven.

[0069] The preset thickness range of the composite material layer located on the surface of the first dielectric layer 202 is 20 angstroms to 500 angstroms.

[0070] The thickness of the plurality of composite layers located in the first opening 203 ranges from 20 angstroms to 1000 angstroms.

[0071] The process of planarizing the composite material layer includes a chemical mechanical polishing process or an etch-back process. In this embodiment, the process of planarizing the composite material layer includes a chemical mechanical polishing process, which can quickly and accurately planarize the composite material layer to a preset position.

[0072] Next, a magnetic tunnel structure is formed on the plurality of composite layers, and a top electrode is formed on the magnetic tunnel structure. 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.

[0073] Please refer to Figure 6 , forming a buffer material layer 207 on the composite material layer; forming a fixed material layer 208 on the buffer material layer 207; forming an insulating material layer 209 on the fixed material layer 208; forming a free material layer 210 on the insulating material layer 209; forming a covering material layer 211 on the free material layer 210; forming a top electrode material layer 212 on the covering material layer 211; forming a patterned mask layer 213 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.

[0074] The buffer material layer 207 provides a material layer for forming a buffer layer; the fixed material layer 208 provides a material layer for forming a fixed layer; the insulating material layer 209 provides a material layer for forming an insulating layer; the free material layer 210 provides a material layer for forming a free layer; the covering material layer 211 provides a material layer for forming a covering layer; and the top electrode material layer 212 provides a material layer for forming a top electrode.

[0075] The material of the buffer material layer 207 includes ruthenium, cobalt or platinum; the material of the fixed material layer 208 includes ferromagnetic material, and the ferromagnetic material includes 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 ferromagnetic material, and the ferromagnetic material includes cobalt iron boron, cobalt iron, nickel iron or cobalt iron nickel; the material of the covering material layer 211 includes magnesium oxide, tantalum or tungsten; the material of the top electrode material layer 212 includes metal, and the metal includes tantalum nitride, titanium nitride, tantalum or titanium; the material of the patterned mask layer 213 includes photoresist or hard mask material, and the hard mask material includes silicon oxide or silicon nitride.

[0076] 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 covering 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.

[0077] Please refer to Figure 7 , using the patterned mask layer 213 as a mask, 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 are etched until the surface of the first dielectric layer 202 is exposed, thereby forming the magnetic tunnel structure and the top electrode 312.

[0078] The magnetic tunnel structure includes: a buffer layer 307 ; a fixed layer 308 located on the buffer layer 307 ; an insulating layer 309 located on the fixed layer 308 ; a free layer 310 located on the insulating layer 309 ; and a capping layer 311 located on the free layer 310 .

[0079] At this time, at least one first electrode layer 304 among the several composite layers formed 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 when an electric field is applied to the magnetic tunnel structure, the magnetic tunnel structure can be better driven.

[0080] The process 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 includes a dry etching process or a wet etching process.

[0081] In this embodiment, the process 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 includes a dry etching process, and the dry etching process can form a magnetic tunnel structure with better sidewall morphology.

[0082] After forming the magnetic tunnel structure, the process of removing the patterned mask layer 213 includes an ashing process.

[0083] Please refer to Figure 8 A stop layer 214 is formed on the sidewall surface of the magnetic tunnel structure, the top surface of the top electrode 312 and the sidewall surface.

[0084] The stop layer 214 is also located on the sidewall surfaces of the plurality of composite layers extending to a portion of the surface of the first dielectric layer 202 .

[0085] The stop layer 214 is used as an etching stop layer when a conductive plug is subsequently formed 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; the material of the stop layer 214 includes silicon nitride, silicon carbide or silicon carbide nitride.

[0086] In this embodiment, the formation process of the stop layer 214 includes an atomic layer deposition process; the material of the stop layer 214 includes silicon nitride.

[0087] Please refer to Fig. 9 An isolation structure 215 is formed on the surface of the stop layer 214 ; a conductive plug 216 is formed in the isolation structure 215 , and the conductive plug 216 is electrically connected to the top electrode 312 .

[0088] The material of the isolation structure 215 includes silicon oxide, silicon oxycarbide, carbon silicon oxyhydride, silicon nitride or silicon oxynitride; the process of forming the isolation structure 215 includes chemical vapor deposition process, physical vapor deposition process or atomic layer deposition process.

[0089] In the present embodiment, the material of the isolation structure 215 includes silicon oxide; the process of forming the isolation structure 215 includes a chemical vapor deposition process, and the chemical vapor deposition process can quickly form an isolation structure 215 with a dense structure and a relatively thick thickness.

[0090] The method for forming the conductive plug 216 includes: forming a mask layer (not shown) on the surface of the isolation structure 215, wherein the mask layer exposes a portion of the surface of the isolation structure 215; etching the isolation structure 215 and the stop layer 214 using the mask layer as a mask until the surface of the top electrode 312 is exposed, thereby 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.

[0091] The conductive plug 216 is used to electrically connect the magnetic random access memory to an external device or conductive structure. The material of the conductive plug 216 includes a combination of 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; the process of planarizing the conductive plug material layer includes a chemical mechanical polishing process or a back etching process.

[0092] In this embodiment, the material of the conductive plug 216 includes copper; the process of forming the conductive plug material layer includes a physical vapor deposition process; the process of etching the isolation structure 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.

[0093] At this point, the magnetic random access memory is formed, and several composite layers in the magnetic random access memory, the composite layer includes a first electrode layer and a second electrode layer. On the one hand, the material of the first electrode layer is different from the material of the second electrode layer, so that the material selection range of the composite layer is wider, and materials with certain resistivity and diffusion barrier capabilities can be selected according to the performance requirements of the device. Among them, the material with low resistivity makes the reading and writing of the magnetic random access memory sensitive and the error rate is small; the material with better diffusion barrier capability can block the mutual diffusion of ions in the first dielectric layer and ions in the magnetic tunnel structure, avoiding the failure of the performance of the magnetic tunnel structure caused by ion diffusion, thereby improving the service life of the magnetic random access memory. On the other hand, the composite layer includes a first electrode layer and a second electrode layer, and the thickness of the composite layer is adjustable, so that the performance satisfaction of the magnetic random access memory is higher, the selection is larger, and the application prospect is broader.

[0094] Accordingly, the embodiment of the present invention also provides a magnetic random access memory formed by the above method, please continue to refer to Fig. 9 ,include:

[0095] substrate;

[0096] A first dielectric layer 202 located on the substrate, wherein the first dielectric layer 202 has a first opening;

[0097] A plurality of composite layers located in the first opening, the plurality of composite layers overlap in a direction perpendicular to the sidewall surface and the bottom surface of the first opening, and the composite layers include a first electrode layer 304 and a second electrode layer 305 located on the surface of the first electrode layer 304, the first electrode layer 304 and the second electrode layer 305 are made of different materials, and at least one first electrode layer 304 of the plurality of composite layers also extends to a partial surface of the first dielectric layer 202;

[0098] A magnetic tunnel structure located on a plurality of composite layers;

[0099] A top electrode 312 located on the magnetic tunnel structure;

[0100] A stop layer 214 located 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 located on the surface of the stop layer 214; and a conductive plug 216 located in the isolation structure 215, wherein the conductive plug 216 is electrically connected to the top electrode 312.

[0101] The material of the first electrode layer includes an amorphous conductive material, and the amorphous conductive material includes tantalum nitride or titanium nitride; the resistivity range of the second electrode material layer 205 is: 60μΩ·cm~100μΩ·cm, and the material includes the material of the second electrode layer includes α-ta or titanium nitride.

[0102] The thickness of the plurality of composite layers in the first opening ranges from 20 angstroms to 1000 angstroms.

[0103] The thickness of the composite layer located on a portion of the surface of the first dielectric layer 202 ranges from 20 angstroms to 500 angstroms.

[0104] The magnetic tunnel structure includes: a buffer layer 307 ; a fixed layer 308 located on the buffer layer 307 ; an insulating layer 309 located on the fixed layer 308 ; a free layer 310 located on the insulating layer 309 ; and a capping layer 311 located on the free layer 310 .

[0105] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A magnetic random access memory, characterized in that: include: substrate; A first dielectric layer located on the substrate, wherein the first dielectric layer has a first opening; A plurality of composite layers located in the first opening, the plurality of composite layers overlap in a direction perpendicular to the sidewall surface and the bottom surface of the first opening, and the composite layers include 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 are made of different materials, the material of the first electrode layer includes an amorphous conductive material, and the resistivity of the second electrode layer is in the range of 60 μΩ·cm to 100 μΩ·cm; A magnetic tunnel structure located on a plurality of composite layers; A top electrode is located on the magnetic tunnel structure.

2. The magnetic random access memory according to claim 1, wherein: The material of the second electrode layer includes α-ta or titanium nitride.

3. The magnetic random access memory according to claim 1, wherein: The amorphous conductive material includes tantalum nitride or titanium nitride.

4. The magnetic random access memory according to claim 1, wherein: The thickness of the plurality of composite layers in the first opening ranges from 20 angstroms to 1000 angstroms.

5. The magnetic random access memory according to claim 4, characterized in that: The thickness of a single layer of the first electrode layer ranges from 1 angstrom to 50 angstroms; the thickness of a single layer of the second electrode layer ranges from 1 angstrom to 50 angstroms.

6. The magnetic random access memory according to claim 1, wherein: At least one first electrode layer among the plurality of composite layers further extends to a portion of the surface of the first dielectric layer.

7. The magnetic random access memory according to claim 1, wherein: The substrate comprises: a base and a device layer located 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; the plurality of composite layers are electrically connected to the substrate.

8. The magnetic random access memory according to claim 1, wherein: The magnetic tunnel structure comprises: a buffer layer; a fixed layer located on the buffer layer; an insulating layer located on the fixed layer; a free layer located on the insulating layer; and a covering layer located on the free layer.

9. The magnetic random access memory according to claim 8, characterized in that: The material of the buffer layer includes ruthenium, cobalt or platinum; the material of the fixed layer includes ferromagnetic material, and 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 ferromagnetic material, and the ferromagnetic material includes cobalt iron boron, cobalt iron, nickel iron or cobalt iron nickel; the material of the covering layer includes magnesium oxide, tantalum or tungsten.

10. The magnetic random access memory according to claim 1, wherein: Also includes: A stop layer is located on the side wall surface of the magnetic tunnel structure, the top surface of the top electrode and the side wall surface.

11. The magnetic random access memory according to claim 10, wherein: Also includes: an isolation structure located on a surface of the stop layer; A conductive plug is located in the isolation structure, and the conductive plug is electrically connected to the top electrode.

12. A method for forming a magnetic random access memory as claimed in any one of claims 1 to 11, characterized in that: include: providing a substrate; forming a first dielectric layer on a substrate, wherein the first dielectric layer has a first opening; forming a plurality of composite layers in the first opening, wherein the plurality of composite layers overlap in a direction perpendicular to the sidewall surface and the bottom surface of the first opening, and the composite layers include a first electrode layer and a second electrode layer located on the surface of the first electrode layer; forming a magnetic tunnel structure on the plurality of composite layers; A top electrode is formed on the magnetic tunnel structure.

13. The method for forming a magnetic random access memory according to claim 12, wherein: At least one first electrode layer among the plurality of composite layers further extends to a portion of the surface of the first dielectric layer.

14. The method for forming a magnetic random access memory according to claim 13, wherein: The method for forming the plurality of composite layers comprises: forming a plurality of overlapping composite material layers on the bottom surface, the side wall surface and the surface of the first dielectric layer of the first opening, each composite material layer comprising a first electrode material layer and a second electrode material layer located on the first electrode material layer; flattening the composite material layers until the composite material layer located on the surface of the first dielectric layer reaches a preset thickness range, thereby forming the plurality of composite layers in the first opening.

15. The method for forming a magnetic random access memory according to claim 14, wherein: The preset thickness range of the composite material layer located on the surface of the first dielectric layer is 20 angstroms to 500 angstroms.

16. The method for forming a magnetic random access memory according to claim 14, wherein: The number of times of repeating the first electrode material layer and the second electrode material layer ranges from 1 to 30.

17. The method for forming a magnetic random access memory according to claim 14, wherein: After forming the composite material layer and before planarizing the composite material layer, the method further includes: 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.

18. The method for forming a magnetic random access memory according to claim 14, wherein: The process of planarizing the composite material layer includes a chemical mechanical polishing process or an etch-back process.

19. The method for forming a magnetic random access memory according to claim 14, wherein: The method for forming the magnetic tunnel structure and the top electrode includes: 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 a portion of the top surface of the top electrode material layer; 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 using the patterned mask layer as a mask until the surface of the first dielectric layer is exposed, thereby forming the magnetic tunnel structure and the top electrode.

20. The method for forming a magnetic random access memory according to claim 13, wherein: After forming the top electrode, the method further includes: forming a stop layer on the side wall surface of the magnetic tunnel structure, the top surface of the top electrode and the side wall surface; forming an isolation structure on the stop layer surface; forming a conductive plug in the isolation structure, wherein the conductive plug is electrically connected to the top electrode.

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