CN113346007A - Magnetic tunnel junction structure and magnetic random access memory thereof - Google Patents
Magnetic tunnel junction structure and magnetic random access memory thereof Download PDFInfo
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Abstract
The application provides a magnetic tunnel knot structure and magnetic random access memory thereof, the ferromagnetic superlattice layer of the anti-ferromagnetic layer of magnetic tunnel knot structure combines with the reference layer, forms to have ultra-thin anti-ferromagnetic layer and reference layer bilayer structure, adjusts anti-ferromagnetic layer with the reference layer is in order to adjust it at the saturated magnetic moment of vertical direction the leakage magnetic field of free layer, it makes the magnetic tunnel knot have the regulation and control ability of the leakage magnetic field write current of relative preferred, is favorable to the promotion of magnetic tunnel knot unit at magnetism, electricity and yield and the miniaturization of device.
Description
Technical Field
The present invention relates to the field of memory technologies, and in particular, to a magnetic tunnel junction structure and a magnetic random access memory thereof.
Background
Magnetic Random Access Memory (MRAM) in a Magnetic Tunnel Junction (MTJ) having Perpendicular Anisotropy (PMA), as a free layer for storing information, there are two magnetization directions in the Perpendicular direction, that is: upward and downward, respectively corresponding to "0" and "1" or "1" and "0" in binary, in practical application, the magnetization direction of the free layer will remain unchanged when reading information or leaving empty; during writing, if a signal different from the existing state is input, the magnetization direction of the free layer will be flipped by one hundred and eighty degrees in the vertical direction. The ability of the mram to maintain the magnetization direction of the free Layer is called Data Retention (Data Retention) or Thermal Stability (Thermal Stability), and the requirement is different in different application situations, and for a typical Non-volatile Memory (NVM), the requirement of Data Retention is to retain Data for at least 10 years at 125 ℃, and the decrease of Data Retention or Thermal Stability is caused by external magnetic field flipping, Thermal disturbance, current disturbance or multiple read/write operations, so an Anti-ferromagnetic Layer (SyAF) superlattice is often used to achieve pinning of the Reference Layer (RL). Antiferromagnetic layer (SyAF) typically contains two superlattice ferromagnetic layers with strong perpendicular anisotropy, with a layer of ruthenium to achieve antiferromagnetic coupling of the two superlattice ferromagnetic layers. However, it is still difficult to effectively reduce the influence of the leakage magnetic field on the free layer.
Disclosure of Invention
In order to solve the above technical problems, an object of the present invention is to provide a magnetic tunnel junction structure and a magnetic random access memory thereof, which implement reference layer pinning, lattice inversion, ferromagnetic coupling enhancement and overall film layer structure thinning.
The purpose of the application and the technical problem to be solved are realized by adopting the following technical scheme.
According to the magnetic tunnel junction structure provided by the application, the structure from top to bottom comprises a Covering Layer (CL), a Free Layer (FL), a Barrier Layer (TB), a Reference Layer (RL), an Anti-ferromagnetic Layer (SyAF), a Seed Layer (SL), and a Buffer Layer (BL).
The Reference Layer (RL) has a structure of Fe, FeB, FeCoB or (Fe or FeB)/(CoB, CoFe, CoFeB, FeC, CoC or CoFeC); the antiferromagnetic layer structure is [ X/Pt ] n/Y/Z, [ X/Pd ] n/Y/Z, CoPt/Z, FePt/Z, NiPt/Z, CoFePt/Z, CoPd/Z, FePd/Z, NiPd/Z and CoFePt/Z; wherein n is more than or equal to 2 and less than or equal to 10; x, Y is selected from one or more of Co, Ni, Fe, CoFe, CoNi, NiFe, NiCo, CoNiFe, FeB, CoB, CoFeB, and the multilayer structure thereof, Z is a composite antiferromagnetic coupling layer, and the material thereof is selected from at least one of Cu, Ir, Rh, Cr, Re, V, Mo, Nb, Zr, W, Ta, Hf, Os, Tc, Mn, or the alloy thereof, or the bilayer structure thereof and the multilayer structure thereof. A composite antiferromagnetic coupling layer for coupling the reference layer and the antiferromagnetic layer, disposed on or combined in the antiferromagnetic layer, formed of a transition metal material capable of forming antiferromagnetic coupling; the antiferromagnetic layer is matched with the composite antiferromagnetic coupling layer to realize effective pinning of the reference layer, and the saturated magnetic moments of the antiferromagnetic layer and the reference layer in the vertical direction are adjusted to adjust the leakage magnetic field of the reference layer.
The technical problem solved by the application can be further realized by adopting the following technical measures.
In an embodiment of the present application, the total thickness of the antiferromagnetic layer is 0.5nm to 5.0 nm; the total thickness of the reference layer is 0.5 nm-1.5 nm.
In one embodiment of the present application, the composite antiferromagnetic coupling layer (Z) is formed of (Ir, Ru, Rh, Cu or Re)/(Cr, Mo, V, W, Ta, Nb, Hf, Zr or a combination thereof) in a left-right order representing a bottom-up structure, and has a total thickness selected as an antiferromagnetic coupling peak.
In an embodiment of the present application, Ir, Ru, Rh, Cu or Re enables antiferromagnetic coupling of the antiferromagnetic layer and the reference layer; cr, Mo, V, W, Ta, Nb, Hf, Zr, or a combination thereof effects lattice transformation from the antiferromagnetic layer having a face centered cubic FCC (111) structure to the reference layer having a body centered cubic BCC (001) structure.
In an embodiment of the present application, the composite antiferromagnetic coupling layer is made of a dual-layer structure of Ru/(Cr, CrMo, CrW, Mo, or W), where Ru is 0.3nm to 0.6nm thick, and Cr, CrMo, CrW, Mo, or W is 0.05nm to 0.5nm thick.
In an embodiment of the present application, the material of the composite antiferromagnetic coupling layer is an Ir/(Cr, CrMo, CrW, Mo, or W) dual-layer structure, where the thickness of Ir is 0.2nm to 0.6nm, and the thickness of Cr, CrMo, CrW, Mo, or W is 0.05nm to 0.5 nm.
In an embodiment of the present application, the antiferromagnetic layer has a perpendicular magnetic anisotropy and has a magnetic moment that is 1.1-1.8 times the magnetic moment of the reference layer.
In an embodiment of the application, the magnetic tunnel junction is subjected to an annealing process, the Magnetic Tunnel Junction (MTJ) structure unit after deposition being annealed at a temperature selected to be not less than 350 ℃, so that the Reference Layer (RL) and the Free Layer (FL) are transformed from an amorphous structure to a crystal structure of body-centered cubic BCC (001) under the templating action of a NaCl-type face-centered cubic FCC (001) barrier layer (TB).
Another object of the present invention is to provide a magnetic random access memory device, which includes the magnetic tunnel junction structure, a top electrode disposed above the magnetic tunnel junction structure, and a bottom electrode disposed below the magnetic tunnel junction structure.
The application has stronger leakage magnetic field (H) through an ultrathin magnetic tunnel junction structureStray) And the write current regulation and control capability are very beneficial to the improvement of the magnetism, the electricity and the yield of the magnetic random access memory and the further miniaturization of the device.
Drawings
FIG. 1 is a diagram illustrating an exemplary MRAM cell structure;
FIG. 2 is a diagram illustrating a magnetic memory cell structure of an embodiment of the magnetic random access memory of the present application;
fig. 3 shows the inter-layer Exchange Coupling (IEC) strength of different transition group metals according to an embodiment of the present invention.
Description of the symbols
10, a bottom electrode; 20, magnetic tunnel junction; 21, a buffer layer; 22, a seed layer; an antiferromagnetic layer 23; 24, a lattice partition layer; 25 reference layer; 26 a barrier layer; 27: a free layer; 28, a covering layer; and 30, a top electrode.
Detailed Description
Refer to the drawings wherein like reference numbers refer to like elements throughout. The following description is based on illustrated embodiments of the application and should not be taken as limiting the application with respect to other embodiments that are not detailed herein.
The following description of the various embodiments refers to the accompanying drawings, which illustrate specific embodiments that can be used to practice the present application. In the present application, directional terms such as "up", "down", "front", "back", "left", "right", "inner", "outer", "side", and the like are merely referring to the directions of the attached drawings. Accordingly, the directional terminology is used for purposes of illustration and understanding, and is in no way limiting.
The terms "first," "second," "third," and the like in the description and in the claims of the present application and in the above-described drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the objects so described are interchangeable under appropriate circumstances. Furthermore, the terms "comprising" and "having," as well as variations thereof, such as, for example, are intended to cover non-exclusive inclusions.
The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts of the present application. Unless the context clearly dictates otherwise, expressions used in the singular form encompass expressions in the plural form. In the present specification, it will be understood that terms such as "including," "having," and "containing" are intended to specify the presence of the features, integers, steps, acts, or combinations thereof disclosed in the specification, and are not intended to preclude the presence or addition of one or more other features, integers, steps, acts, or combinations thereof. Like reference symbols in the various drawings indicate like elements.
The drawings and description are to be regarded as illustrative in nature, and not as restrictive. In the drawings, elements having similar structures are denoted by the same reference numerals. In addition, the size and thickness of each component shown in the drawings are arbitrarily illustrated for understanding and ease of description, but the present application is not limited thereto.
In the drawings, the range of configurations of devices, systems, components, circuits is exaggerated for clarity, understanding, and ease of description. It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present.
In addition, in the description, unless explicitly described to the contrary, the word "comprise" will be understood to mean that the recited components are included, but not to exclude any other components. Further, in the specification, "on.
To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description is provided with reference to the accompanying drawings and specific embodiments for a magnetic tunnel junction structure and a magnetic random access memory thereof according to the present invention, and the specific structures, features and effects thereof are described in detail.
FIG. 1 is a diagram of an exemplary MRAM cell structure. The magnetic memory cell structure comprises a multi-layer structure formed by at least a bottom electrode 10, a magnetic tunnel junction 20 and a top electrode 30.
In some embodiments, the bottom electrode 10 is titanium Ti, titanium nitride TiN, tantalum Ta, tantalum nitride TaN, ruthenium Ru, tungsten W, tungsten nitride WN, or combinations thereof; the top electrode 30 is made of Ti, TiN, Ta, TaN, W, WN or their combination. The magnetic memory cell structure is typically implemented by Physical Vapor Deposition (PVD), and is typically planarized after deposition to achieve surface flatness for the magnetic tunnel junction 20.
In some embodiments, the magnetic tunnel junction 20 comprises a Capping Layer (CL)28, a Free Layer (FL)27, a Barrier Layer (TB) 26, a Reference Layer (RL)25, a lattice Breaking Layer (CBL) 24, an antiferromagnetic Anti-ferromagnetic Layer (SyAF)23, a Seed Layer (Seed Layer, SL)22, and a Buffer Layer (BL) 21.
As shown in fig. 1, the antiferromagnetic Layer 23 includes a first superlattice ferromagnetic Layer (the 1st ferromagnetic super-Layer, 1st FM-SL), an antiferromagnetic coupling Layer and a second superlattice ferromagnetic Layer (the 2nd ferromagnetic super-Layer, 2nd FM-SL) respectively disposed from bottom to top. A ferromagnetic superlattice layer formed of a transition metal having a face-centered crystal structure in combination with a ferromagnetic material; the antiferromagnetic coupling layer is arranged on the ferromagnetic superlattice layer and is formed by a metal material capable of forming antiferromagnetic coupling; the second ferromagnetic superlattice layer is arranged on the antiferromagnetic coupling layer and is formed by combining a transition metal with a face-centered crystal structure with a ferromagnetic material; wherein the antiferromagnetic coupling layer combines the ferromagnetic superlattice layer and the second ferromagnetic superlattice layer to perform antiferromagnetic coupling of the ferromagnetic superlattice layer, and the magnetic tunnel junction includes lattice conversion and strong ferromagnetic coupling between the antiferromagnetic layer and the reference layer.
In the magnetic tunnel junction 20 with perpendicular anisotropy, the free layer 27 functions to store information, possessing two magnetization directions in the perpendicular direction, namely: up and down, corresponding to "0" and "1" or "1" and "0" in the binary, respectively. The magnetization direction of the free layer 27 remains unchanged when information is read or left empty; during writing, if a signal of a different state from that of the existing state is input, the magnetization direction of the free layer 27 is inverted by 180 degrees in the vertical direction. The ability of the free layer 27 of a magnetic random access memory to maintain a constant magnetization direction is called Data Retention (Data Retention) or Thermal Stability (Thermal Stability). The data retention capacity can be calculated using the following formula:
wherein tau is the time when the magnetization vector is unchanged under the condition of thermal disturbance, tau0For the trial time (typically 1ns), E is the energy barrier of the free layer, kBBoltzmann constant, T is the operating temperature.
The Thermal Stability factor (Thermal Stability factor) can then be expressed as the following equation:
wherein, KeffIs the effective isotropic energy density of the free layer, V is the volume of the free layer, KVConstant of bulk anisotropy MsSaturation susceptibility of the free layer, demagnetization constant in the direction perpendicular to Nz, t thickness of the free layer, KiCD is the critical dimension of the magnetic random access memory (i.e., the diameter of the free layer), A, as the interfacial anisotropy constantsFor stiffness integral exchange constant, DnThe critical dimension of the free layer for different domain switching patterns. Experiments show that when the thickness of the free layer is thicker, the free layer shows in-plane anisotropy, and when the thickness of the free layer is thinner, the free layer shows vertical anisotropy, KVGenerally negligible, while the contribution of demagnetization energy to the perpendicular anisotropy is negative, so the perpendicular anisotropy comes entirely from the interfacial effect (K)i)。
In some embodiments, the thermal stability factor is also affected by the static magnetic Field, particularly the leakage magnetic Field (Stray Field) from the reference layer 25, in combination with the difference in the magnetization direction applied by the static magnetic Field on the free layer 27, to produce an enhancement or reduction effect. As shown in fig. 1, in order to reduce the influence of the leakage magnetic field on the Free Layer (FL)27, an antiferromagnetic layer (SyAF)23 having a strong perpendicular anisotropy (PMA) superlattice structure is typically added below the Reference Layer (RL) 25.
Due to the presence of the antiferromagnetic layer 23, the leakage magnetic field from the reference layer 25 and the antiferromagnetic layer 23 can be partially cancelled out, quantitatively, defining the total leakage magnetic field from the reference layer 25 and the antiferromagnetic layer 23 as HStray：
Wherein Hk effIs a perpendicular effective anisotropy field, Hk eff＝2(Keff/(μ0Ms)). Further, defining the magnetization vector perpendicular to the free layer and upward as positive, the leakage magnetic field perpendicular to the free layer 27 upward is positive. Then the thermal stability factor for the magnetization vectors of the free layer 27 and the reference layer 25 in the case of parallel or antiparallel orientations, respectively, can be expressed as the following equation:
as the volume of the magnetic free layer 27 is reduced, the smaller the spin-polarized current to be injected for writing or switching operation. Critical current I for write operationc0The relationship between the compound and the thermal stability is strongly related, and can be expressed as the following formula:
wherein alpha is a damping constant,
η is the spin polarizability, which is the approximate planck constant. Further, the critical current can be expressed as the following expressions when the magnetizations are parallel and antiparallel, respectively:
in this case, the critical current of the magnetic random access memory in the parallel state and the anti-parallel state can be further controlled by controlling the leakage magnetic Field (Stray Field). In addition, when etching the Magnetic Tunnel Junction (MTJ) cell array, in order to reduce the re-deposition of the conductive metal, the thickness of the Magnetic Tunnel Junction (MTJ) film layer also needs to be reduced.
In some embodiments, the magnetic tunnel junction 20, which is the core memory cell of the magnetic random access memory, must also be compatible with CMOS processes and must be able to withstand long term annealing at 400 ℃.
Fig. 2 is a schematic diagram of a magnetic memory cell structure of the magnetic random access memory of the present application, and fig. 3 is an exemplary illustration of the inter-layer Exchange Coupling (IEC) strength of different transition group metals of the present application, please refer to fig. 1 for understanding. The magnetic tunnel junction structure provided by the present application includes, from top to bottom, a capping layer 28, a free layer 27, a barrier layer 26, a reference layer 25, an antiferromagnetic layer 23, a seed layer 22, and a buffer layer 21.
The structure of the reference layer is Fe, FeB, FeCoB or (Fe or FeB)/(CoB, CoFe, CoFeB, FeC, CoC or CoFeC); the antiferromagnetic layer structure is [ X/Pt ]]n/Y/Z，[X/Pd]nY/Z, CoPt/Z, FePt/Z, NiPt/Z, CoFePt/Z, CoPd/Z, FePd/Z, NiPd/Z, CoFePt/Z; wherein n is more than or equal to 2 and less than or equal to 10; x, Y is selected from one or more of Co, Ni, Fe, CoFe, CoNi, NiFe, NiCo, CoNiFe, FeB, CoB, CoFeB, and the multilayer structure thereof, Z is a composite antiferromagnetic coupling layer, and the material thereof is selected from at least one of Cu, Ir, Rh, Cr, Re, V, Mo, Nb, Zr, W, Ta, Hf, Os, Tc, Mn, or the alloy thereof, or the bilayer structure thereof and the multilayer structure thereof. A composite antiferromagnetic coupling layer for coupling the reference layer and the antiferromagnetic layer, disposed on or combined in the antiferromagnetic layer, formed of a transition metal material capable of forming antiferromagnetic coupling; the antiferromagnetic layer is matched with the composite antiferromagnetic coupling layer to realize effective pinning of the reference layer, and the saturated magnetic moments of the antiferromagnetic layer and the reference layer in the vertical direction are adjusted to adjust the leakage magnetic field of the reference layer.
In an embodiment of the present application, the total thickness of the antiferromagnetic layer is 0.5nm to 5.0 nm; the total thickness of the reference layer is 0.5 nm-1.5 nm.
In an embodiment of the present application, the composite antiferromagnetic coupling layer (Z) is formed of (Ir, Ru, Rh, Cu or Re)/(Cr, Mo, V, W, Ta, Nb, Hf, Zr or a combination thereof) in a left-right order representing a bottom-up structure, and has a total thickness selected as an antiferromagnetic coupling peak, Ir, Ru, Rh, Cu or Re being used to realize antiferromagnetic coupling of the antiferromagnetic layer and the reference layer; cr, Mo, V, W, Ta, Nb, Hf, Zr, or combinations thereof are used to achieve lattice transformation from the antiferromagnetic layer having a face centered cubic FCC (111) structure to the reference layer having a body centered cubic BCC (001) structure.
In some embodiments, as shown in fig. 3, the layer structure of Cr, Mo, V, W, Ta, Nb, Hf, Zr or their combination has an absorption capability of B or C, and at the same time, an additional RKKY antiferromagnetic Coupling can be provided due to the presence of the layer, in which case, the RKKY antiferromagnetic Coupling (IEC) energy density is not damaged compared to the single layer structure.
In some embodiments, the material of the composite antiferromagnetic coupling layer is a Ru/(Cr, CrMo, CrW, Mo or W) double-layer structure, the thickness of Ru is 0.3 nm-0.6 nm, and the thickness of Cr, CrMo, CrW, Mo or W is 0.05 nm-0.5 nm.
In some embodiments, the material of the composite antiferromagnetic coupling layer is an Ir/(Cr, CrMo, CrW, Mo or W) double-layer structure, wherein the thickness of Ir is 0.2nm to 0.6nm, and the thickness of Cr, CrMo, CrW, Mo or W is 0.05nm to 0.5 nm.
In some embodiments, the Bottom Electrode (BE)10 is made of Ti, TiN, Ta, TaN, Ru, W, WN or a combination thereof, and is typically implemented by Physical Vapor Deposition (PVD), and is typically planarized after deposition to achieve surface flatness for fabricating the magnetic tunnel junction; the Top Electrode (TE)30 is made of Ti, TiN, Ta, TaN, W, WN or their combination.
In some embodiments, the Buffer Layer (BL)21 is generally composed of Ta, Ti, TiN, TaN, W, WN, Ru, Pt, O, N, CoB, FeB, CoFeB, or combinations thereof. The Seed Layer (SL)22 generally comprises Pt, Ru, Cr, etc. having an FCC (111) crystal structure for optimizing the crystal structure of the subsequent synthetic ferromagnetic layer (SyAF) 23.
In some embodiments, the barrier layer 26 of the magnetic tunnel junction 20 is formed of a non-magnetic metal oxide having a thickness between 0.6nm and 1.5nm, the non-magnetic metal oxide including magnesium oxide MgO, magnesium zinc oxide MgZn2O4Zinc oxide ZnO and aluminum oxide Al2O3MgN, Mg boron oxide, Mg3B2O6Or Mg3Al2O6. Preferably, magnesium oxide MgO may be used.
In one embodiment of the present application, the free layer 27 of the magnetic tunnel junction 20 has variable magnetic polarization, and the material of the free layer 27 is generally composed of Fe, Co, Ni, CoFe, CoB, FeB, CoFeB, W, Mg, Zr, Al, Zn, Nb, Mo, Ta, Hf, Zr, V, Cr, Mg, Ti or Ru. Further, a single layer structure selected from cobalt boride CoB, iron boride FeB, cobalt iron boron CoFeB, or a double layer structure of cobalt boride CoFe/cobalt iron boron CoFeB, or iron Fe/cobalt iron boron CoFeB/(tungsten W, molybdenum Mo, vanadium V, niobium Nb, chromium Cr, hafnium Hf, titanium Ti, zirconium Zr, tantalum Ta, scandium Sc, yttrium Y, zinc Zn, ruthenium Ru, osmium, rhodium Rh, iridium Ir, palladium Pd and/or platinum Pt)/cobalt iron boron CoFeB, cobalt iron boron CoFeB/(tungsten W, molybdenum Mo, vanadium V, niobium Nb, chromium Cr, hafnium Hf, titanium Ti, zirconium Zr, tantalum Ta, scandium Sc, yttrium Y, zinc Zn, ruthenium Ru, osmium Os, rhodium Rh, iridium Ir, palladium Pd and/or platinum Pt)/cobalt iron boron, or a triple layer structure of iron/cobalt iron boron/(tungsten W, molybdenum Mo, vanadium V, niobium V, niobium, ruthenium, hafnium Zr, tantalum Ta, scandium Pd and/or platinum Pt)/cobalt iron boron may be used, A four-layer structure of yttrium Y, zinc Zn, ruthenium Ru, osmium Os, rhodium Rh, iridium Ir, palladium Pd and/or platinum Pt)/CoFeB, cobalt ferrite/CoFeB/(tungsten W, molybdenum Mo, vanadium V, niobium Nb, chromium Cr, hafnium Hf, titanium Ti, zirconium Zr, tantalum Ta, scandium Sc, yttrium Y, zinc Zn, ruthenium Ru, osmium Os, rhodium Rh, iridium Ir, palladium Pd and/or platinum Pt)/CoFeB; the thickness of the free layer 27 is between 1.0 nm and 3.0 nm.
In one embodiment of the present application, after the deposition of the Free Layer (FL)27, a Capping Layer (CL)28 is again deposited, the material of the capping layer 28 being selected from (Mg, MgO, MgZn, magnesium oxide)2O4Magnesium boron oxide Mg3B2O6Or magnesium aluminum oxide Mg3Al2O6One of the two layers is a double-layer structure of (one of) tungsten W, molybdenum Mo, magnesium Mg, niobium Nb, ruthenium Ru, hafnium Hf, vanadium V, chromium Cr and platinum Pt), or a three-layer structure of magnesium oxide MgO/(one of tungsten W, molybdenum Mo and hafnium Hf)/ruthenium Ru, or magnesium oxide/platinum/(one of tungsten, molybdenum and hafnium Hf)Or one of hafnium)/ruthenium. In some embodiments, the selection of magnesium oxide (MgO) can provide a source of additional interfacial anisotropy for the Free Layer (FL)26, thereby increasing thermal stability.
In an embodiment of the present application, the antiferromagnetic layer has a perpendicular magnetic anisotropy and has a magnetic moment that is 1.1-1.8 times the magnetic moment of the reference layer.
In one embodiment of the present application, an annealing process is performed on the magnetic tunnel junction 20, which is selected to anneal the Magnetic Tunnel Junction (MTJ) structure unit after deposition at no less than 350 ℃, so that the reference layer 25 and the free layer 27 are transformed from an amorphous structure to a body-centered-cubic stacked crystal structure under the templating effect of the sodium chloride (NaCl) type face-centered-cubic crystal structure barrier layer 26.
Referring again to fig. 2, in an embodiment of the present application, a magnetic random access memory includes a plurality of memory cells, including any of the aforementioned magnetic tunnel junction 20 structures, a top electrode 30 disposed above the magnetic tunnel junction 20 structure, and a bottom electrode 10 disposed below the magnetic tunnel junction 20 structure.
In one embodiment of the present application, the bottom electrode 10, the magnetic tunnel junction 20, and the top electrode 30 are all formed by a physical vapor deposition process.
The application has stronger leakage magnetic field (H) through an ultrathin magnetic tunnel junction structureStray) And the write current regulation and control capability are very beneficial to the improvement of the magnetism, the electricity and the yield of the magnetic random access memory and the further miniaturization of the device.
The terms "in one embodiment of the present application" and "in various embodiments" are used repeatedly. This phrase generally does not refer to the same embodiment; it may also refer to the same embodiment. The terms "comprising," "having," and "including" are synonymous, unless the context dictates otherwise.
Although the present application has been described with reference to specific embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application, and all changes, substitutions and alterations that fall within the spirit and scope of the application are to be understood as being covered by the following claims.
Claims (9)
1. A magnetic tunnel junction structure is arranged between a bottom electrode and a top electrode of a magnetic random access memory unit, the magnetic tunnel junction structure comprises a covering layer, a free layer, a barrier layer, a reference layer, an antiferromagnetic layer, a seed layer and a buffer layer from top to bottom, and the antiferromagnetic layer is characterized in that the structure of the antiferromagnetic layer is [ X/Pt ]]n/Y/Z,[X/Pd]nY/Z, CoPt/Z, FePt/Z, NiPt/Z, CoFePt/Z, CoPd/Z, FePd/Z, NiPd/Z, CoFePt/Z, representing the bottom-up structure in the order of their left and right; wherein n is more than or equal to 2 and less than or equal to 10; x, Y is selected from one or more of Co, Ni, Fe, CoFe, CoNi, NiFe, NiCo, CoNiFe, FeB, CoB and CoFeB, or a bilayer structure thereof and a multilayer structure thereof, and Z is a composite antiferromagnetic coupling layer.
2. The magnetic tunnel junction structure of claim 1 wherein the reference layer structure is Fe, FeB, FeCoB or (Fe or FeB)/(CoB, CoFe, CoFeB, FeC, CoC or CoFeC).
3. The magnetic tunnel junction structure of claim 2 wherein the reference layer has a total thickness of 0.5nm to 1.5 nm.
4. The magnetic tunnel junction structure of claim 1 wherein the antiferromagnetic layer has a total thickness of 0.5nm to 5.0 nm.
5. The magnetic tunnel junction structure of claim 1 wherein the composite antiferromagnetic coupling layer is (Ir, Ru, Rh, Cu or Re)/(Cr, Mo, V, W, Ta, Nb, Hf, Zr or combinations thereof) representing a bottom-up structure in left-right order and has a total thickness selected to be the antiferromagnetic coupling peak.
6. The magnetic tunnel junction structure of claim 5 wherein the material of the composite antiferromagnetic coupling layer is a double layer of Ru/(Cr, CrMo, CrW, Mo or W), the thickness of Ru is 0.3nm to 0.6nm, and the thickness of Cr, CrMo, CrW, Mo or W is 0.05nm to 0.5 nm.
7. The magnetic tunnel junction structure of claim 5 wherein the material of the composite antiferromagnetically coupled layer is a double layer of Ir/(Cr, CrMo, CrW, Mo or W), wherein the thickness of Ir is 0.2nm to 0.6nm and the thickness of Cr, CrMo, CrW, Mo or W is 0.05nm to 0.5 nm.
8. The magnetic tunnel junction structure of claim 1 wherein the antiferromagnetic layer has perpendicular magnetic anisotropy and has a magnetic moment that is 1.1-1.8 times the magnetic moment of the reference layer.
9. A magnetic random access memory comprising the magnetic tunnel junction structure of any of claims 1-8, a top electrode disposed above the magnetic tunnel junction structure, and a bottom electrode disposed below the magnetic tunnel junction structure.
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