WO2021142817A1

WO2021142817A1 - Magnetic memory

Info

Publication number: WO2021142817A1
Application number: PCT/CN2020/072929
Authority: WO
Inventors: 赵巍胜; 熊丹荣; 彭守仲
Original assignee: 北京航空航天大学
Priority date: 2020-01-19
Filing date: 2020-01-19
Publication date: 2021-07-22

Abstract

Provided in the present invention is a magnetic memory, comprising: a first anti-ferromagnetic layer used for providing an exchange bias field; an insertion layer arranged on the anti-ferromagnetic layer and used for blocking diffusion of the material of the first anti-ferromagnetic layer during an annealing process; a free ferromagnetic layer structure arranged on the insertion layer; a first barrier layer arranged on the free ferromagnetic layer structure; and a reference ferromagnetic layer structure arranged on the first barrier layer and having a fixed magnetisation direction; the magnetisation direction of the free ferromagnetic layer structure is parallel or anti-parallel to the magnetisation direction of the reference ferromagnetic layer structure. The present invention has a high annealing temperature, and is compatible with CMOS post thermal treatment processes.

Description

Magnetic storage

Technical field

The present invention relates to the technical field of magnetic tunnel junctions, and in particular to a magnetic memory.

Background technique

The basic storage unit of traditional magnetic memory (Magnetic Random Access Memory, MRAM) is a magnetic tunnel junction (MTJ). The core part is a sandwich structure formed by two ferromagnetic layers sandwiching a tunneling barrier layer. One of the ferromagnetic layers has the same magnetization direction and is called the reference layer. The other ferromagnetic layer is called the free layer. When its magnetization direction is parallel or antiparallel to the reference layer, the magnetic tunnel junction is in a low-resistance or high-resistance state, respectively. The two resistance states can represent binary data "0" and "1" respectively, which is the basic principle of MRAM data storage.

The data writing operation of MRAM is realized by reversing the magnetization direction of the free layer in the MTJ. Among them, the use of Spin-Orbit Torque (SOT) can achieve fast and reliable magnetization reversal. This data writing technology requires adding a heavy metal or topological insulator that can generate spin-orbit moment under the MTJ free layer, and the spin-orbit moment caused by the current flowing through the film is used to drive the magnetization inversion of the free layer. However, for magnetic tunnel junctions with perpendicular magnetic anisotropy (Perpendicular Magnetic Anisotropy, PMA), it is usually necessary to apply an external magnetic field in the in-plane direction at the same time to determine the magnetization of the free layer when using the spin-orbit moment to realize data writing. Reversing the polarity to achieve deterministic magnetization reversal, but this greatly increases the circuit complexity and at the same time reduces the stability of the ferromagnetic layer, which becomes the biggest obstacle to the practical application of the method for limiting the spin-orbit moment data writing.

In 2016, some researchers discovered that the use of antiferromagnetic/ferromagnetic structures can generate an in-plane exchange bias field, which can replace an external magnetic field, thereby realizing a spin-orbital moment-based exchange bias field that does not require an external magnetic field. Deterministic magnetization flip. However, an obvious disadvantage of this structure is that the annealing temperature is low and cannot be compatible with the CMOS post heat treatment process.

Summary of the invention

The main purpose of the embodiments of the present invention is to provide a magnetic memory to increase the annealing temperature so as to be compatible with the CMOS post-heat treatment process.

In order to achieve the foregoing objective, an embodiment of the present invention provides a magnetic memory, including:

The first antiferromagnetic layer is used to provide an exchange bias field;

The insertion layer is arranged on the antiferromagnetic layer and is used to block the diffusion of the material of the first antiferromagnetic layer during the annealing process;

Free ferromagnetic layer structure, set on the insertion layer;

The first barrier layer is set on the free ferromagnetic layer structure;

With reference to the ferromagnetic layer structure, it is arranged on the first barrier layer and has a fixed magnetization direction;

Wherein, the magnetization direction of the free ferromagnetic layer structure is parallel or antiparallel to the magnetization direction of the reference ferromagnetic layer structure.

In one of the embodiments, it further includes:

Buffer layer; the first antiferromagnetic layer is disposed on the buffer layer.

In one of the embodiments, it further includes:

Substrate; the buffer layer is arranged on the substrate.

In one of the embodiments, it further includes:

Artificial antiferromagnetic layer; the artificial antiferromagnetic layer is set on the reference ferromagnetic layer structure.

In one of the embodiments, it further includes:

Covering layer; the covering layer is arranged on the artificial antiferromagnetic layer.

In one of the embodiments, it further includes:

Protective layer; the protective layer is arranged on the cover layer.

In one of the embodiments, the free ferromagnetic layer structure includes: a first ferromagnetic layer;

The reference ferromagnetic layer structure includes: a second ferromagnetic layer.

In one of the embodiments, the free ferromagnetic layer structure includes: a third ferromagnetic layer;

The reference ferromagnetic layer structure includes:

A fourth ferromagnetic layer, a first metal layer, a fifth ferromagnetic layer, and a second barrier layer;

The fourth ferromagnetic layer is arranged on the first barrier layer;

The first metal layer is located between the fourth ferromagnetic layer and the fifth ferromagnetic layer;

The fifth ferromagnetic layer is located between the first metal layer and the second barrier layer.

In one of the embodiments, the free ferromagnetic layer structure includes:

The sixth ferromagnetic layer, the second metal layer and the seventh ferromagnetic layer;

The sixth ferromagnetic layer is arranged on the insertion layer;

The second metal layer is located between the sixth ferromagnetic layer and the seventh ferromagnetic layer;

The reference ferromagnetic layer structure includes: an eighth ferromagnetic layer.

In one of the embodiments, the free ferromagnetic layer structure includes:

The ninth ferromagnetic layer, the third barrier layer and the tenth ferromagnetic layer;

The ninth ferromagnetic layer is arranged on the insertion layer;

The third barrier layer is located between the ninth ferromagnetic layer and the tenth ferromagnetic layer;

The reference ferromagnetic layer structure includes: the eleventh ferromagnetic layer.

The magnetic memory of the embodiment of the present invention includes: a first antiferromagnetic layer, used to provide an exchange bias field; an insertion layer, arranged on the antiferromagnetic layer, used to block the material of the first antiferromagnetic layer during the annealing process Diffusion; free ferromagnetic layer structure, set on the insertion layer; first barrier layer, set on the free ferromagnetic layer structure; refer to the ferromagnetic layer structure, set on the first barrier layer, with a fixed magnetization direction, The magnetization direction of the free ferromagnetic layer structure is parallel or antiparallel to the magnetization direction of the reference ferromagnetic layer structure. The invention has the characteristics of high annealing temperature and can be compatible with the CMOS post heat treatment process.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the accompanying drawings needed in the description of the embodiments. Obviously, the accompanying drawings in the following description are only of the present invention. For some embodiments, those of ordinary skill in the art can obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic diagram of a magnetic memory in the first embodiment of the present invention;

Figure 2 is a schematic diagram of a magnetic memory in a second embodiment of the present invention;

Fig. 3 is a schematic diagram of a magnetic memory in a third embodiment of the present invention;

Figure 4 is a schematic diagram of a magnetic memory in a fourth embodiment of the present invention;

Fig. 5 is a schematic diagram of a magnetic memory in a fifth embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

In view of the problem that the prior art has a low annealing temperature and cannot be compatible with the CMOS post-heat treatment process, an embodiment of the present invention provides a magnetic memory compatible with the CMOS post-heat treatment process. The present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of a magnetic memory in the first embodiment of the present invention. As shown in Figure 1, magnetic storage includes:

The first antiferromagnetic layer is used to provide an exchange bias field;

Wherein, the first antiferromagnetic layer is one or any combination of platinum manganese (PtMn), iridium manganese (IrMn), palladium manganese (PdMn) and iron manganese (FeMn), and the thickness may be 1 nm-10 nm. The common element ratio of PtMn can be Pt ₅₀ Mn ₅₀ , Pt ₂₀ Mn ₈₀ , Pt ₂₅ Mn ₇₅ or Pt ₇₅ Mn ₂₅ and other materials; the common element ratio of IrMn is Ir ₅₀ Mn ₅₀ , Ir ₂₀ Mn ₈₀ or Ir ₂₅ Mn ₇₅ and other materials; the common element ratio of PdMn is Pd ₅₀ Mn ₅₀ , Pd ₉₀ Mn ₁₀ or Pd ₇₅ Mn ₂₅ ; the common element ratio of FeMn is Fe ₅₀ Mn ₅₀ or Fe ₈₀ Mn ₂₀ , among the above materials The number represents the percentage of the element.

Wherein, the insertion layer can be one or any combination of tungsten (W), molybdenum (Mo), chromium (Cr), and iridium (Ir); the thickness of the insertion layer is 0.1 nm-3 nm.

Free ferromagnetic layer structure, set on the insertion layer;

The first barrier layer is set on the free ferromagnetic layer structure;

Fig. 2 is a schematic diagram of a magnetic memory in the second embodiment of the present invention. As shown in FIG. 2, the free ferromagnetic layer structure may include: a first ferromagnetic layer; the reference ferromagnetic layer structure may include: a second ferromagnetic layer.

The thickness of the first ferromagnetic layer and the second ferromagnetic layer may be 0.5nm-2nm, and the material and thickness of the first ferromagnetic layer and the second ferromagnetic layer may be different.

Fig. 3 is a schematic diagram of a magnetic memory in a third embodiment of the present invention. As shown in Figure 3, the free ferromagnetic layer structure may include:

Third ferromagnetic layer;

The reference ferromagnetic layer structure may include:

The fourth ferromagnetic layer is arranged on the first barrier layer;

The reference ferromagnetic layer structure in the third embodiment of the present invention can improve the magnetic anisotropy of the reference ferromagnetic layer structure.

Fig. 4 is a schematic diagram of a magnetic memory in a fourth embodiment of the present invention. As shown in Figure 4, the free ferromagnetic layer structure may include:

The sixth ferromagnetic layer is arranged on the insertion layer;

The reference ferromagnetic layer structure may include: an eighth ferromagnetic layer.

The free ferromagnetic layer structure in the fourth embodiment of the present invention can improve the magnetic anisotropy of the free ferromagnetic layer structure, while further preventing the material of the first antiferromagnetic layer from diffusing to the free ferromagnetic layer structure and the first barrier layer The interface, thereby further increasing the annealing temperature.

Fig. 5 is a schematic diagram of a magnetic memory in a fifth embodiment of the present invention. As shown in Figure 5, the free ferromagnetic layer structure may include:

The ninth ferromagnetic layer is arranged on the insertion layer;

The reference ferromagnetic layer structure may include: an eleventh ferromagnetic layer.

The free ferromagnetic layer structure in the fifth embodiment of the present invention can improve the magnetic anisotropy of the free ferromagnetic layer structure, and at the same time further prevent the material of the first antiferromagnetic layer from diffusing to the free ferromagnetic layer structure and the first barrier layer The interface, thereby further increasing the annealing temperature.

Among them, the first ferromagnetic layer, the third ferromagnetic layer, the sixth ferromagnetic layer, the seventh ferromagnetic layer, the ninth ferromagnetic layer and the tenth ferromagnetic layer may be cobalt iron boron (CoFeB), iron boron (FeB ), one or any combination of cobalt iron (CoFe), iron (Fe) and Heusler alloy (Heusler Alloy).

The second ferromagnetic layer, the fourth ferromagnetic layer, the fifth ferromagnetic layer, the eighth ferromagnetic layer, and the eleventh ferromagnetic layer can be cobalt iron boron (CoFeB), iron boron (FeB), cobalt iron (CoFe) One or any combination of iron (Fe) and Heusler alloy (Heusler Alloy).

The common element ratio of cobalt-iron-boron can be Co ₂₀ Fe ₆₀ B ₂₀ , Co ₄₀ Fe ₄₀ B ₂₀ or Co ₆₀ Fe ₂₀ B ₂₀ ; the common element ratio of iron-boron can be Fe ₈₀ B ₂₀ ; cobalt-iron The ratio of commonly used elements can be materials such as Co ₅₀ Fe ₅₀ , Co ₂₀ Fe ₈₀ or Co ₈₀ Fe ₂₀ ; the Hesler alloy can be materials such as cobalt iron aluminum (Co ₂ FeAl) or cobalt manganese silicon (Co ₂ MnSi); The numbers in the above materials represent the percentage of elements.

The first barrier layer, the second barrier layer, and the third barrier layer refer to thin film layers formed of insulator materials such as metal oxides, which can be magnesium oxide, aluminum oxide, magnesium aluminum oxide, hafnium oxide, and One or any combination of tantalum oxides, such as magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), or magnesium meta aluminate (MgAl ₂ O ₄ ). The thickness of the first barrier layer, the second barrier layer, and the third barrier layer may be 0.2 nm-1.5 nm.

The first metal layer and the second metal layer may be tungsten (W), molybdenum (Mo), chromium (Cr), iridium (Ir), tantalum (Ta), ruthenium (Ru), niobium (Nb), platinum (Pt) One or any combination of palladium (Pd) and silver (Ag); the thickness of the first metal layer and the second metal layer can be 0.1nm-3nm.

In one of the embodiments, it further includes: a buffer layer; and the first antiferromagnetic layer is disposed on the buffer layer.

Wherein, the buffer layer may be a metal material or an alloy material, such as one or any combination of tantalum (Ta), iridium (Ir), hafnium (Hf), bismuth (Bi) and molybdenum (Mo), and the thickness may be 0.2nm -200nm.

In one of the embodiments, it further includes: a substrate; the buffer layer is disposed on the substrate.

Among them, the substrate may be a material with stable chemical properties and a smooth surface, such as silicon (Si) or glass.

In one of the embodiments, it further includes: an artificial antiferromagnetic layer; the artificial antiferromagnetic layer is arranged on the reference ferromagnetic layer structure.

Among them, the artificial antiferromagnetic layer is used to enhance the magnetic anisotropy and magnetization direction of the reference ferromagnetic layer structure. The materials that make up the artificial antiferromagnetic layer are ruthenium (Ru) layer, multiple first cobalt nickel (Co/Ni) layers, ruthenium (Ru) layer and multiple second cobalt nickel (Co/Ni) layers from bottom to top. Floor. The number of the first cobalt-nickel (Co/Ni) layer is different from the number of the second cobalt-nickel (Co/Ni) layer; the overall appearance of the first cobalt-nickel layer is the first magnetization direction, and the overall appearance of the second cobalt-nickel layer is The second magnetization direction, and the first magnetization direction is opposite to the second magnetization direction.

In one of the embodiments, it further includes: a cover layer; the cover layer is arranged on the artificial antiferromagnetic layer.

Wherein, the covering layer may be a metal material or an alloy material, such as one or any combination of tantalum (Ta), iridium (Ir), hafnium (Hf), bismuth (Bi), tungsten (W) and molybdenum (Mo), The thickness can be 0.2nm-200nm.

In one of the embodiments, it further includes: a protective layer; the protective layer is disposed on the cover layer.

Wherein, the protective layer may be a metallic material or a non-metallic material. For example, the protective layer may be _{one or any combination of tantalum (Ta), ruthenium (Ru) and silicon dioxide (SiO 2} ), and the thickness may be 0.5 nm- 1000nm.

When preparing the magnetic memory of the embodiment of the present invention, traditional magnetron sputtering, molecular beam epitaxy, or atomic layer deposition can be used to grow each layer of material on a thermally oxidized substrate or other multilayer film in the order from bottom to top. Then, the magnetic memory is manufactured through processing techniques such as photolithography and etching, and the cross-sectional area of each film layer is basically the same, and the cross-sectional shape is generally one of a circle, an ellipse, a square, or a rectangle.

One of the specific embodiments of the present invention is as follows:

The material of the buffer layer is tantalum with a thickness of 2nm; the material of the cover layer is tungsten with a thickness of 3nm; the material of the antiferromagnetic layer is an iridium-manganese alloy with a thickness of 5nm; the material of the insertion layer is tungsten with a thickness of 0.5nm; The material of a ferromagnetic layer is Co ₂₀ Fe ₆₀ B ₂₀ with a thickness of 1.1 nm; the material of the first barrier layer is magnesium oxide with a thickness of 1 nm; the material of the second ferromagnetic layer is Co ₂₀ Fe ₆₀ B ₂₀ with a thickness It is 1nm; the material of the protective layer is silicon dioxide, and the thickness is 5nm.

Because tungsten, the material of the insertion layer, can block the diffusion of manganese during the annealing process, the magnetic memory of the present invention has a high annealing temperature. At the same time, because the interface between tungsten and cobalt-iron-boron has strong perpendicular magnetic anisotropy, the magnetic memory of the present invention has strong perpendicular magnetic anisotropy and thermal stability. In addition, after reducing the cross-sectional area of the present invention within a certain range, the present invention can still maintain high thermal stability, and therefore can reduce the size of the device and increase the magnetic storage density. Because the insertion layer uses heavy metal material tungsten with a higher spin Hall angle, the magnetic memory of the present invention has a higher charge flow-spin current conversion efficiency, a smaller critical switching current, and lower power consumption. Because the materials of the insertion layer and the cover layer in the present invention are both tungsten, and the materials of the two ferromagnetic layers are both cobalt-iron-boron, a symmetrical tungsten/cobalt-iron-boron/magnesium oxide/cobalt-iron-boron/ The tungsten structure helps to obtain a strong tunneling magnetoresistance; at the same time, the tungsten/cobalt-iron-boron/magnesium oxide/cobalt-iron-boron/tungsten structure has a strong resonance tunneling effect, so that a strong tunneling can be obtained Magnetoresistance helps to improve the reliability of data reading of magnetic memory. Finally, the insertion of tungsten at the interface between the iridium-manganese alloy and the cobalt-iron-boron may enhance the in-plane exchange bias field, thereby helping to determine the magnetization reversal.

In addition, if the material of the insertion layer is selected as Cr, the present invention has the characteristic of high annealing temperature and can be compatible with the CMOS post-heat treatment process. If the material of the insertion layer is selected as Mo, in addition to the advantage of high annealing temperature, the present invention also has the characteristics of strong perpendicular magnetic anisotropy, which can improve thermal stability and ensure the reliability of data reading; if further formation of related barriers With the layer symmetrical Mo/CoFeB/MgO/CoFeB/Mo structure, the present invention also has the characteristic of high tunneling magnetoresistance, which can improve the reliability and stability of data reading.

In summary, the magnetic memory of the embodiment of the present invention includes: a first antiferromagnetic layer for providing an exchange bias field; an insertion layer, which is provided on the antiferromagnetic layer, for blocking the first antiferromagnetic layer during the annealing process Diffusion of the material; free ferromagnetic layer structure, set on the insertion layer; first barrier layer, set on the free ferromagnetic layer structure; refer to the ferromagnetic layer structure, set on the first barrier layer, free ferromagnetic The magnetization direction of the layer structure is parallel or antiparallel to the magnetization direction of the reference ferromagnetic layer structure. The invention has the characteristics of high annealing temperature and can be compatible with the CMOS post heat treatment process. The invention also has the characteristics of strong perpendicular magnetic anisotropy, small critical switching current, and high tunneling magnetoresistance rate, which can ensure the reliability and stability of data storage and reading, reduce power consumption, and realize deterministic magnetization switching.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in further detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. The scope of protection, any modification, equivalent replacement, improvement, etc., made within the spirit and principle of the present invention shall be included in the scope of protection of the present invention.

Claims

A magnetic memory is characterized in that it comprises:

The first antiferromagnetic layer is used to provide an exchange bias field;

The insertion layer is arranged on the antiferromagnetic layer and is used to block the diffusion of the material of the first antiferromagnetic layer during the annealing process;

A free ferromagnetic layer structure, arranged on the insertion layer;

The first barrier layer is arranged on the free ferromagnetic layer structure;

With reference to the ferromagnetic layer structure, it is arranged on the first barrier layer and has a fixed magnetization direction;

Wherein, the magnetization direction of the free ferromagnetic layer structure is parallel or antiparallel to the magnetization direction of the reference ferromagnetic layer structure.
The magnetic memory according to claim 1, further comprising:

Buffer layer; the first antiferromagnetic layer is disposed on the buffer layer.
The magnetic memory according to claim 2, further comprising:

The substrate; the buffer layer is provided on the substrate.
The magnetic memory according to claim 1, further comprising:

Artificial antiferromagnetic layer; the artificial antiferromagnetic layer is arranged on the reference ferromagnetic layer structure.
The magnetic memory according to claim 4, further comprising:

Covering layer; The covering layer is arranged on the artificial antiferromagnetic layer.
The magnetic memory according to claim 5, further comprising:

Protective layer; The protective layer is arranged on the covering layer.
The magnetic memory according to any one of claims 1 to 6, characterized in that,

The free ferromagnetic layer structure includes: a first ferromagnetic layer;

The reference ferromagnetic layer structure includes: a second ferromagnetic layer.
The magnetic memory according to any one of claims 1 to 6, characterized in that,

The free ferromagnetic layer structure includes: a third ferromagnetic layer;

The reference ferromagnetic layer structure includes:

A fourth ferromagnetic layer, a first metal layer, a fifth ferromagnetic layer, and a second barrier layer;

The fourth ferromagnetic layer is disposed on the first barrier layer;

The first metal layer is located between the fourth ferromagnetic layer and the fifth ferromagnetic layer;

The fifth ferromagnetic layer is located between the first metal layer and the second barrier layer.
The magnetic memory according to any one of claims 1 to 6, wherein the free ferromagnetic layer structure comprises:

The sixth ferromagnetic layer, the second metal layer and the seventh ferromagnetic layer;

The sixth ferromagnetic layer is disposed on the insertion layer;

The second metal layer is located between the sixth ferromagnetic layer and the seventh ferromagnetic layer;

The reference ferromagnetic layer structure includes: an eighth ferromagnetic layer.
The magnetic memory according to any one of claims 1 to 6, wherein the free ferromagnetic layer structure comprises:

The ninth ferromagnetic layer, the third barrier layer and the tenth ferromagnetic layer;

The ninth ferromagnetic layer is disposed on the insertion layer;

The third barrier layer is located between the ninth ferromagnetic layer and the tenth ferromagnetic layer;

The reference ferromagnetic layer structure includes: an eleventh ferromagnetic layer.