Magnetic random access memory and spin-orbit torque magnetic device manufacturing method

Abstract

A spin-orbit torque (SOT) magnetic device includes: a bottom metal layer; a first magnetic layer disposed over the bottom metal layer; a spacer layer disposed over the first magnetic layer; and a second magnetic layer disposed over the spacer layer. A diffusion barrier layer for suppressing diffusion of a metal element of the first magnetic layer into the bottom metal layer is provided between the bottom metal layer and the first magnetic layer. The embodiment of the invention also relates to a manufacturing method of a spin-orbit torque (SOT) magnetic device.

Description

[0001] Case Analysis

[0002] This application is a divisional application of the patent application filed on September 20, 2019, entitled "Spin-orbit torque (SOT) magnetic device and manufacturing method thereof", with patent application number 201910891688.X. Technical Field

[0003] Embodiments of the present invention relate to methods for manufacturing magnetic random access memory (MRAM) and spin-orbit torque (SOT) magnetic devices. Background Technology

[0004] MRAM offers performance comparable to volatile static random access memory (SRAM) and density and lower power consumption comparable to volatile dynamic random access memory (DRAM). Compared to non-volatile memory (NVM) flash memory, MRAM provides much faster access times and suffers minimal degradation over time, while flash memory can only be rewritten a limited number of times. One type of MRAM is spin-orbit torque random access memory (STT-RAM). STT-RAM utilizes a magnetic tunnel junction (MTJ) that is at least partially written by a current driven through the MTJ. Another type of MRAM is spin-orbit torque RAM (SOT-RAM). Summary of the Invention

[0005] An embodiment of the present invention provides a spin-orbit torque (SOT) magnetic device, comprising: a bottom metal layer; a first magnetic layer disposed above the bottom metal layer; a spacer layer disposed above the first magnetic layer; a second magnetic layer disposed above the spacer layer; and a diffusion barrier layer disposed between the bottom metal layer and the first magnetic layer, wherein the diffusion barrier layer inhibits the diffusion of metal elements from the first magnetic layer into the bottom metal layer.

[0006] Another embodiment of the present invention provides a spin-orbit torque (SOT) magnetic device, comprising: a bottom metal layer; a first magnetic layer disposed above the bottom metal layer; a spacer layer disposed above the first magnetic layer; a second magnetic layer disposed above the spacer layer; a magnetic dead layer disposed between the bottom metal layer and the first magnetic layer; and a diffusion barrier layer disposed between the magnetic dead layer and the first magnetic layer, wherein: the diffusion barrier layer inhibits the diffusion of metal elements from the first magnetic layer into the bottom metal layer.

[0007] Another embodiment of the present invention provides a method for manufacturing a spin-orbit torque (SOT) magnetic device, the method comprising: forming a first magnetic layer over a bottom metal layer; processing the first magnetic layer such that a diffusion barrier layer is formed between the bottom metal layer and the first magnetic layer; forming a spacer layer over the first magnetic layer; forming an intermediate metal layer over the spacer layer; and forming a second magnetic layer over the intermediate metal layer, wherein the diffusion barrier layer inhibits the diffusion of metal elements from the first magnetic layer into the bottom metal layer during a subsequent thermal process exceeding 450°C. Attached Figure Description

[0008] Figure 1A This is a schematic diagram of an SOT MRAM cell according to an embodiment of the present invention.

[0009] Figure 1B This is a schematic diagram of an SOT MRAM cell according to an embodiment of the present invention.

[0010] Figure 2A , Figure 2B , Figure 2C and Figure 2D A schematic cross-sectional view of the manufacturing operation of an SOT MRAM cell according to an embodiment of the present invention is shown.

[0011] Figure 3A , Figure 3B , Figure 3C and Figure 3D Experimental results on the perpendicular magnetic anisotropy of SOT magnetic devices with and without diffusion barrier layers are shown.

[0012] Figure 4A and Figure 4B The experimental results of secondary ion mass spectrometry are shown. Detailed Implementation

[0013] It should be understood that the following disclosure provides many different embodiments or examples for implementing the invention with different features. Specific embodiments or examples of components and arrangements are described below to simplify the invention. These are merely examples and not intended to be limiting. For example, the dimensions of elements are not limited to the disclosed range or values, but may depend on process conditions and / or the performance required by the device. Furthermore, in the following description, forming a first component on or over a second component can include embodiments where the first and second components are in direct contact, and may also include embodiments where additional components can be formed between the first and second components, such that the first and second components are not in direct contact. For simplicity and clarity, the various components may be drawn at arbitrary scales. In the drawings, some layers / components may be omitted for simplicity.

[0014] Furthermore, for ease of description, spatial relation terms such as “below,” “under,” “lower,” “above,” and “upper” may be used herein to describe the relationship between one element or component and another element or component as shown in the figures. In addition to the orientations shown in the figures, spatial relation terms are intended to include different orientations of the device during use or operation. The device may be positioned in other ways (rotated 90 degrees or in other orientations), and the spatial relation descriptors used herein may be interpreted accordingly. Furthermore, the term “made of” may mean “comprising” or “consisting of.” Additionally, in the manufacturing process described below, one or more additional operations may exist during or between the described operations, and the order of operations may be changed. Unless otherwise described, in this invention, the phrase “one of A, B, and C” means “A, B, and / or C” (A, B, C, A and B, A and C, B and C, or A, B, and C), and does not imply an element from A, an element from B, and an element from C.

[0015] In spin-orbit torque-type magnetic devices, the thermal stability of perpendicular magnetic anisotropy (PMA) is one of the key performance indicators. PMA is affected by the interface between the spin-orbit active layer (e.g., a heavy metal layer) and the free magnetic layer (e.g., a data storage layer). In particular, interface diffusion can degrade PMA performance. Defects and non-ideal structures at the interface can lead to PMA instability and a thick magnetic dead layer (MDL), where ferromagnetic order is lost. This invention relates to a novel interface between the spin-orbit active layer and the free magnetic layer to address the aforementioned problems in SOT magnetic devices.

[0016] Figure 1A This is a schematic diagram of a SOT MRAM cell (SOT magnetic device) utilizing spin-orbit interaction during switching, according to an embodiment of the present invention.

[0017] The SOT magnetic device includes a bottom metal layer 10 formed above a support layer 5 as a spin-orbit interaction active layer. Furthermore, the SOT magnetic device includes a first magnetic layer 20 (the first magnetic layer 20 is a free magnetic layer or data storage layer) disposed above the bottom metal layer 10, a non-magnetic spacer layer 30 disposed above the first magnetic layer, and a second magnetic layer 40 (as a reference layer) disposed above the non-magnetic spacer layer 30. In some embodiments, a top conductive layer 50 serving as an electrode is disposed above the second magnetic layer 40. Additionally, as... Figure 1A As shown, in an embodiment of the present invention, a diffusion barrier layer 100 is disposed between the bottom metal layer 10 and the first magnetic layer 20.

[0018] The magnetic moment of the free layer 20 (first magnetic layer) is switched using spin-orbit interaction effects. In some embodiments, only spin-orbit interaction effects are used to switch the magnetic moment of the first magnetic layer 20. In other embodiments, a combination of effects is used to switch the magnetic moment of the first magnetic layer 20. For example, spin-transfer torque, as the primary effect, is used to switch the magnetic moment of the first magnetic layer 20, and the spin-transfer torque may be assisted by torque caused by spin-orbit interaction. In other embodiments, the primary switching mechanism is the torque caused by spin-orbit interaction. In such embodiments, another effect, including but not limited to spin-transfer torque, may assist the switching.

[0019] The bottom metal layer 10 is a spin-orbit active layer with strong spin-orbit interactions and can be used to switch the magnetic moment of the first magnetic layer 20. The bottom metal layer 10 is used to generate a spin-orbit magnetic field H. More specifically, a current driven in the plane passing through the bottom metal layer 10 and the accompanying spin-orbit interactions can generate a spin-orbit magnetic field H. This spin-orbit magnetic field H is equivalent to the spin-orbit torque T when magnetized, where T = -γ[M×H] in the first magnetic layer 20. Therefore, torque and magnetic field are interchangeably referred to as the spin-orbit field and spin-orbit torque. This reflects the fact that spin-orbit interactions are the origin of spin-orbit torque and spin-orbit field. For a current driven in the plane in the bottom metal layer 10 and spin-orbit interactions, spin-orbit torque occurs. Conversely, spin-transfer torque is caused by a vertical plane current flowing through the first magnetic layer 20, the non-magnetic spacer layer 30, and the second magnetic layer 40 (reference layer), which injects spin-polarized charge carriers into the first magnetic layer 20. A spin-orbit torque T can rapidly deflect the magnetic moment of the first magnetic layer 20 from an equilibrium state parallel to the easy axis. The spin-orbit torque T can tilt the magnetization of the first magnetic layer 20 much faster than a conventional STT torque of similar maximum amplitude. In some embodiments, the switching can be accomplished using spin-orbit torque. In other embodiments, another mechanism, such as spin transfer, can be used to accomplish the switching. Therefore, the resulting spin-orbit field / spin-orbit torque can be used to switch the magnetic moment of the first magnetic layer 20.

[0020] In some embodiments, the interaction of the bottom metal layer includes a spin Hall effect. For the spin Hall effect, the current in the plane of the bottom metal layer 10 (i.e., in-plane current, essentially within) Figure 1A In the xy plane, the driving current Je is perpendicular to the stacking direction of the film including the bottom metal layer 10 and the first magnetic layer 20 (i.e., perpendicular to the surface normal). Figure 1AA driving current Je is generated in the z-direction of the surface. Charge carriers with spins of specific orientations perpendicular to the current direction and the surface normal (z-direction) accumulate at the surface of the bottom metal layer 10. Most of these spin-polarized charge carriers diffuse into the first magnetic layer 20 (free layer). This diffusion results in a torque T on the magnetization of the first magnetic layer 20. Since the torque on the magnetization is equal to the effective magnetic field on the magnetization, as described above, the spin accumulation equivalently results in a magnetic field H on the first magnetic layer 20. The spin orbital field of the spin Hall effect is the cross product of the spin orbital polarization and the magnetic moment of the first magnetic layer 20. Therefore, the magnitude of the torque is proportional to the planar current density Je and the spin polarization of the charge carriers. The spin Hall effect can be used for switching when the polarization caused by the spin Hall effect is parallel to the easy axis of the first magnetic layer 20. Figure 1A The magnetic stacked layers are shown. To obtain the spin-orbit torque T, a current pulse is driven in a plane passing through the bottom metal layer 10. The resulting spin-orbit torque T counteracts the damping torque, which causes the magnetization of the first magnetic layer 20 to switch in a manner similar to conventional STT switching.

[0021] As described above, the bottom metal layer 10 is a spin-orbit active layer that induces strong spin-orbit interactions with the first magnetic layer 20 (free layer). In some embodiments, the bottom metal layer 10 comprises one or more heavy metals or materials doped with heavy metals. In some embodiments, α-W, β-W, and / or β-Ta are used as the bottom metal layer 10. In some embodiments, the thickness of the bottom metal layer 10 is in the range of about 2 nm to 20 nm, and in other embodiments, it is in the range of about 5 nm to 15 nm.

[0022] The first magnetic layer 20, serving as the data storage layer, is a free layer with a switchable magnetic moment. In some embodiments, the first magnetic layer 20 includes a cobalt-iron-boron (CoFeB) layer, a cobalt / palladium (CoPd) layer, and / or a cobalt-iron (CoFe) layer with a thickness ranging from about 0.6 nm to about 1.2 nm. In other embodiments, the first magnetic layer 20 includes a multilayer magnetic material. In some embodiments, the first magnetic layer is Fe. x Co y B 1-x-y Where 0.50≤x≤0.70 and 0.10≤y≤0.30. In other embodiments, 0.55≤x≤0.65 and 0.15≤y≤0.25.

[0023] The nonmagnetic spacer layer 30 is made of a dielectric material and serves as a tunneling barrier. In some embodiments, the nonmagnetic spacer layer 30 comprises a crystalline or amorphous magnesium oxide (MgO) layer. In other embodiments, the nonmagnetic spacer layer 30 is made of aluminum oxide or a conductive material such as Cu. In some embodiments, the thickness of the nonmagnetic spacer layer 30 is in the range of about 0.3 nm to about 1.2 nm, and in other embodiments, the thickness of the nonmagnetic layer 30 is in the range of about 0.5 nm to about 1.0 nm. In this invention, "elemental layer" or "compound layer" generally refers to an element or compound content greater than 99%.

[0024] The second magnetic layer 40 is a reference layer with an invariant magnetic moment. In some embodiments, the second magnetic layer 40 is made of the same material as the first magnetic layer 20 as described above. In some embodiments, the second magnetic layer 40 comprises a multilayer magnetic material. In some embodiments, the second magnetic layer 40 comprises a multilayer structure of cobalt (Co) and platinum (Pt). In some embodiments, the thickness of the second magnetic layer 40 is in the range of about 0.2 nm to about 1.0 nm, and in other embodiments it is in the range of about 0.3 nm to about 0.5 nm.

[0025] In some embodiments, the second magnetic layer 40 is a multilayer comprising a synthetic antiferromagnetic layer having ferromagnetic layers separated by non-magnetic layers (such as Ru). In some embodiments, a pinning layer (such as an antiferromagnetic layer that holds the magnetic moment of the second magnetic layer 40 in place) is disposed above the second magnetic layer 40, and a Ru layer is inserted between the pinning layer and the second magnetic layer 40. In some embodiments, the first and second magnetic layers are crystals.

[0026] The top conductive layer 50, which serves as the electrode, comprises one or more layers of Ta, Ru, Au, Cr, and Pt.

[0027] The support layer 5 is made of a dielectric material, such as silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, magnesium oxide, or any other suitable material. In some embodiments, the support layer 5 is a shallow trench isolation layer, an interlayer dielectric (ILD) layer, or an intermetallic dielectric (IMD) layer in a semiconductor device.

[0028] In this invention, a diffusion barrier layer 100 is disposed between the bottom metal layer 10 and the first magnetic layer 20 to improve the interface properties between them. In some embodiments, the diffusion barrier layer 100 can suppress the diffusion of metal elements in the first magnetic layer 20 into the bottom metal layer 10. When the first magnetic layer 20 is in direct contact with the bottom metal layer 10, a relatively thick magnetic dead layer is formed, and metal elements (such as Fe and Co) in the first magnetic layer 20 diffuse into the bottom metal layer through a subsequent thermal process at about 300°C to about 450°C.

[0029] In this invention, such as Figure 1A As shown, a diffusion barrier layer 100, which inhibits the diffusion of metal elements in the first magnetic layer 20 into the bottom metal layer 10, is disposed between the first magnetic layer 20 and the bottom metal layer 10. In some embodiments, the thickness of the diffusion barrier layer is in the range of about 0.1 nm to about 0.6 nm, and in other embodiments, it is in the range of about 0.2 nm to about 0.5 nm.

[0030] In some embodiments, the first magnetic layer 20 comprises iron and cobalt, and therefore the diffusion barrier layer 100 inhibits the diffusion of iron and / or cobalt from the first magnetic layer 20 to the bottom metal layer 10. In some embodiments, the diffusion barrier layer 100 is an iron-rich layer comprising iron, and the atomic percentage of iron in the diffusion barrier layer 100 is higher than the atomic percentage of iron in the first magnetic layer 20. In some embodiments, the atomic percentage of iron in the diffusion barrier layer 100 is higher on the first magnetic layer side than on the bottom metal layer side. In some embodiments, the amount of iron gradually decreases from the first magnetic layer side to the bottom metal layer side.

[0031] In some embodiments, the first magnetic layer 20 further includes boron, and the diffusion barrier layer 100 also includes boron. The atomic percentage of boron in the first magnetic layer 20 may be the same as or different from the atomic percentage of boron in the diffusion barrier layer 100. In some embodiments, the atomic percentage of boron in the diffusion barrier layer 100 is higher than the atomic percentage of boron in the first magnetic layer 20.

[0032] In some embodiments, the first magnetic layer 20 is Fe x Co y B 1-x-y As described above, and the diffusion barrier layer 100 is Fe z B 1-z , where z > x. In some embodiments, 0.50 ≤ x ≤ 0.70, 0.10 ≤ y ≤ 0.30 and 0.65 ≤ z ≤ 0.90. In other embodiments, 0.55 ≤ x ≤ 0.65, 0.15 ≤ y ≤ 0.25 and 0.65 ≤ z ≤ 0.75.

[0033] In some embodiments, the diffusion barrier layer 100 is a cobalt-rich layer, and the atomic percentage of cobalt is higher than that of cobalt in the first magnetic layer 20. In some embodiments, the atomic percentage of cobalt in the diffusion barrier layer 100 is higher on the first magnetic layer side than on the bottom metal layer side. In some embodiments, the amount of cobalt gradually decreases from the first magnetic layer side to the bottom metal layer side.

[0034] The diffusion barrier layer 100 may be made of other materials. In some embodiments, the diffusion barrier layer 100 is made of a non-magnetic metallic material, such as magnesium. In other embodiments, the diffusion barrier layer 100 is made of a dielectric material, such as a metal oxide. In some embodiments, the metal oxide is an oxide of a metal contained in the bottom metal layer. In some embodiments, the metal oxide is one of tungsten oxide and tantalum oxide.

[0035] Figure 1B This is a schematic diagram of an SOT MRAM cell according to another embodiment of the present invention. In the following embodiments, it can be used with... Figure 1A The materials, configurations, dimensions, and / or processes described in the foregoing embodiments are the same or similar, and their detailed descriptions may be omitted.

[0036] Similar to Figure 1A A bottom metal layer 10 is formed above the support layer 5. In some embodiments, the bottom metal layer 10 is a β-W layer. A first magnetic layer 20, serving as a free layer or reference layer, is formed above the bottom metal layer 10. In some embodiments, the first magnetic layer 20 comprises iron and cobalt. In some embodiments, the first magnetic layer 20 further comprises boron. A non-magnetic spacer layer 30, made of, for example, magnesium oxide, is formed above the first magnetic layer 20, and a second magnetic layer 40 is formed above the non-magnetic spacer layer 30.

[0037] In some embodiments, an intermediate metal layer 60 is disposed between the non-magnetic spacer layer 30 and the second magnetic layer 40. In some embodiments, the intermediate metal layer 60 is made of a non-magnetic material. In some embodiments, the intermediate metal layer 60 is made of Mg. In some embodiments, the thickness of the intermediate metal layer 60 is in the range of about 0.1 nm to about 0.6 nm, and in other embodiments, it is in the range of about 0.2 nm to about 0.5 nm. In other embodiments, no intermediate metal layer is used.

[0038] like Figure 1B As shown, in some embodiments, an antiferromagnetic layer 70 is formed over the second magnetic layer, and a third magnetic layer 80 is formed over the antiferromagnetic layer 70. The antiferromagnetic layer 70 helps to fix the magnetic moment of the second magnetic layer 40. In some embodiments, the antiferromagnetic layer 70 comprises ruthenium (Ru) or any other suitable antiferromagnetic material. In some embodiments, the thickness of the antiferromagnetic layer 70 is in the range of about 0.2 nm to about 0.8 nm.

[0039] The third magnetic layer 80 comprises one or more layers of magnetic material. In some embodiments, the third magnetic layer 80 comprises one or more of cobalt, iron, nickel, and platinum. In some embodiments, the material of the third magnetic layer 80 may be the same as or different from the material of the second magnetic layer 40. In some embodiments, the third magnetic layer 80 is a CoPt layer. In some embodiments, the thickness of the third magnetic layer is in the range of about 0.5 nm to about 1.5 nm, and in other embodiments, it is in the range of about 0.7 nm to about 1.2 nm.

[0040] In addition, such as Figure 1B As shown, a diffusion barrier layer 100 is disposed between the bottom metal layer 10 and the first magnetic layer 20 to prevent metal elements of the first magnetic layer 20 from diffusing into the bottom metal layer 10. The diffusion barrier layer 100 is one of the following: an iron-rich layer having a higher percentage of iron atoms than the first magnetic layer; a cobalt-rich layer having a higher percentage of cobalt atoms than the first magnetic layer; a magnesium layer; a tungsten oxide layer; and a tantalum oxide layer.

[0041] In some embodiments, iridium is included in either the diffusion barrier layer 100 or the intermediate metal layer. Figure 1B As shown, in some embodiments, the iridium-containing layer is inserted between any two adjacent layers. The iridium-containing layer can be one selected from the group consisting of an iridium layer, an iridium oxide layer, a bilayer structure of an iridium layer and an iridium oxide layer, an iridium-titanium nitride layer, a bilayer structure of an iridium layer and a tantalum layer, and a binary alloy layer of iridium and tantalum.

[0042] Figure 1A and Figure 1B Each layer shown can be formed by a suitable film formation method, including physical vapor deposition (PVD) (including sputtering); molecular beam epitaxy (MBE); pulsed laser deposition (PLD); atomic layer deposition (ALD); electron beam epitaxy; chemical vapor deposition (CVD); or derivative CVD processes (including low-pressure CVD (LPCVD), ultra-high vacuum CVD (UHVCVD), reduced pressure CVD (RPCVD)); electroplating or any combination thereof.

[0043] In some embodiments, a film stack is formed by the above-described film formation operation, and after the film stack is formed, a patterning operation including one or more photolithography and etching operations is performed on the film stack to form a shape such as... Figure 1A The SOT unit shown.

[0044] Figures 2A to 2C The sequential manufacturing operations for forming the diffusion barrier layer 100 according to an embodiment of the present invention are shown. It should be understood that... Figures 2A to 2CAdditional operations are provided before, during, and after the process shown, and for additional embodiments of the method, some of the operations described below may be replaced or eliminated. The order of operations / processes may be interchangeable.

[0045] like Figure 2A As shown, a bottom metal layer 10 is formed above the support layer 5. The bottom metal layer 10 can be formed by PVD, CVD, ALD, or any other suitable film formation method. Then, as... Figure 2B As shown, the first magnetic layer 20 is formed using PVD, CVD, ALD, or any other suitable film formation method. Figure 2B As shown, after the formation of the first magnetic layer 20, a magnetic dead layer 22 is formed between the first magnetic layer 20 and the bottom metal layer 10. The magnetic dead layer 22 adversely affects the performance of the SOT magnetic device. The thickness of the magnetic dead layer 22 is in the range of about 0.2 nm to about 0.8 nm.

[0046] Then, as Figure 2C As shown, a process for manufacturing an iron-rich diffusion barrier layer 100 is performed. In some embodiments, this process is a hot annealing process. The process temperature of the hot annealing process is in the range of about 350°C to about 450°C, and in other embodiments, in the range of about 375°C to 425°C. In some embodiments, the process time of the hot annealing is in the range of about 30 minutes to about 240 minutes, and in other embodiments, in the range of about 90 minutes to about 180 minutes. Figure 2C As shown, an iron-rich layer is formed as a diffusion barrier layer 100 through a thermal annealing process. In some embodiments, the thickness of the magnetic dead layer 22 is reduced. In some embodiments, the thickness of the magnetic dead layer 22 is about 0.1 nm to about 0.3 nm after the thermal annealing process. In certain embodiments, the magnetic dead layer 22 disappears.

[0047] In other embodiments, a plasma processing process for fabricating an iron / cobalt-rich diffusion barrier layer 100 is performed. In such... Figure 2B After the formation of the first magnetic layer 20, the first magnetic layer 20 is subjected to plasma. In some embodiments, the plasma is at least one of argon, nitrogen, and hydrogen. RF plasma, inductively coupled plasma (ICP), electron cyclotron resonance (ECR) plasma, or any other plasma can be used. In some embodiments, the plasma treatment process time ranges from 1 minute to 60 minutes, and in other embodiments, from about 10 minutes to about 30 minutes. In some embodiments, the stacked structure is heated at a temperature ranging from about 250°C to about 450°C during the plasma treatment. Figure 2CAs shown, an iron-rich layer is formed as a diffusion barrier layer 100 through plasma treatment. In some embodiments, the thickness of the magnetic dead layer 22 is reduced. In some embodiments, the thickness of the magnetic dead layer 22 is about 0.1 nm to about 0.3 nm after plasma treatment. In certain embodiments, the magnetic dead layer 22 disappears.

[0048] In addition, such as Figure 2D As shown, when the diffusion barrier layer 100 is an oxide of tungsten or tantalum, it can be formed by directly oxidizing the surface of the bottom metal layer 10 made of tungsten or tantalum. The oxidation process includes thermal oxidation, plasma oxidation, or wet chemical oxidation. After forming the tungsten or tantalum oxide as the diffusion barrier layer 100, the first magnetic layer 20 is formed.

[0049] In other embodiments, the diffusion barrier layer 100 is formed by a deposition method, such as PVD, CVD, MBE, ALD, electroplating, or any other suitable method.

[0050] Figure 3A , Figure 3B , Figure 3C and Figure 3D Experimental results demonstrating the perpendicular magnetic anisotropy (PDA) of an SOT magnetic device exhibiting the effect of the diffusion barrier layer 100 according to the present invention are shown. Figures 3A to 3D In the diagram, the horizontal direction represents the magnetic field (Oe), and the vertical axis represents the magneto-optical Kerr effect (MOKE). Figure 3A and Figure 3C The perpendicular magnetic anisotropy of the SOT magnetic unit without a diffusion barrier layer is shown, and Figure 3B and Figure 3D The perpendicular magnetic anisotropy of an SOT magnetic unit with a diffusion barrier layer 100 is shown. Figure 3A and Figure 3B The initially formed perpendicular magnetic anisotropy is shown, and Figure 3C and Figure 3D The perpendicular magnetic anisotropy of the SOT magnetic unit after undergoing a thermal process at 400°C for 50 minutes is shown. (Example) Figure 3A and Figure 3B As shown, both the SOT magnetic cell without and with a diffusion barrier layer exhibit good perpendicular magnetic anisotropy results with significant hysteresis. However, after heating the SOT magnetic cell without a diffusion barrier layer at 400°C, no hysteresis was observed in the perpendicular magnetic anisotropy results. Conversely, even after heating the SOT magnetic cell with a diffusion barrier layer at 400°C, good hysteresis was observed in the perpendicular magnetic anisotropy results. These results indicate that the diffusion barrier layer 100 according to the present invention can improve the thermal stability of the SOT magnetic cell.

[0051] Figure 4A and Figure 4B Experimental results demonstrating the effect of the diffusion barrier layer 100 according to the present invention are shown. Figure 4A and Figure 4B The results were obtained using energy-dispersive X-ray spectroscopy (EDX). The sample used in EDX analysis consists of a silicon oxide support layer, a tungsten layer as the bottom metal layer, a cobalt-iron-boron layer as the first magnetic layer, a magnesium oxide layer as the non-magnetic spacer layer, a Mg layer as the middle metal layer, a cobalt-iron-boron layer as the second magnetic layer, and a Ru layer. Figure 4A The sample also includes an iron boron layer as a diffusion barrier, and Figure 4B The sample and Figure 4A Same as above, except that it does not include a diffusion barrier layer. The sample was heat-treated at 400°C for 50 minutes.

[0052] In this experiment, the first and second magnetic layers are Fe 0.6 Co 0.2 B 0.2 And the diffusion barrier layer is Fe 0.7 B 0.3 The tungsten layer is about 10 nm thick, the first magnetic layer is about 0.8 nm thick, the magnesium oxide layer is about 1.0 nm thick, the Mg layer is about 0.3 nm thick, the second magnetic layer is about 0.4 nm thick, and the Ru layer is about 3 nm thick.

[0053] like Figure 4B As shown, significant amounts of iron (Fe) and cobalt (Co) diffuse into the tungsten layer, while... Figure 4A As shown, the diffusion of iron and cobalt into the tungsten layer is effectively suppressed. See also Figures 3A to 3D as well as Figure 4A and Figure 4B By using the diffusion barrier layer 100, the diffusion of iron and cobalt from the first conductive layer to the tungsten layer (bottom metal layer) can be effectively suppressed, thereby improving the thermal stability of the SOT magnetic device.

[0054] When the SOT magnetic cell has high thermal stability, it is easier to integrate the SOT magnetic cell as a MRAM into a semiconductor device. In some embodiments, the MRAM device is formed at the back-to-end (BEOL) stage of the entire semiconductor manufacturing operation. In BEOL, the structure formed above the semiconductor substrate undergoes one or more thermal operations from about 400°C to about 450°C. Therefore, the SOT magnetic cell of the present invention is compatible with the BEOL process of semiconductor manufacturing processes.

[0055] In some embodiments, the MRAM cell includes Figure 1A The SOT magnetic device shown includes a current source 110 and a switching element 120 (such as a transistor).

[0056] It should be understood that not all advantages need to be discussed herein, no particular advantage is required in all embodiments or examples, and other embodiments or examples may provide different advantages.

[0057] For example, in this invention, a diffusion barrier layer is inserted between a bottom metal layer (spin-orbit active layer) and a first magnetic layer (free magnetic layer). The diffusion barrier layer inhibits the diffusion of metallic elements (such as iron and cobalt) contained in the first magnetic layer into the bottom metal layer. Therefore, interface properties can be improved. For example, the thickness of the magnetic dead layer can be reduced. Furthermore, the diffusion barrier layer specifically inhibits the diffusion of metallic elements during subsequent heating processes. Therefore, the spin-orbit torque (SOT) magnetic device of this invention exhibits improved perpendicular magnetic anisotropy (PMA) and is compatible with semiconductor device fabrication processes.

[0058] According to aspects of the present invention, a spin-orbit torque (SOT) magnetic device includes: a bottom metal layer; a first magnetic layer disposed above the bottom metal layer; a spacer layer disposed above the first magnetic layer; and a second magnetic layer disposed above the spacer layer. A diffusion barrier layer for inhibiting the diffusion of a metal element from the first magnetic layer into the bottom metal layer is disposed between the bottom metal layer and the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer includes iron and cobalt. In one or more of the foregoing and following embodiments, the diffusion barrier layer includes iron, and the atomic percentage of iron in the diffusion barrier layer is higher than the atomic percentage of iron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer further includes boron, and the diffusion barrier layer further includes boron. In one or more of the foregoing and following embodiments, the atomic percentage of boron in the diffusion barrier layer is higher than the atomic percentage of boron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer is Fe. x Co y B 1-x-y And the diffusion barrier layer is Fe z B 1-zWhere z > x. In one or more of the foregoing and following embodiments, 0.50 ≤ x ≤ 0.70 and 0.65 ≤ z ≤ 0.90. In one or more of the foregoing and following embodiments, the diffusion barrier layer comprises cobalt, and the atomic percentage of cobalt in the diffusion barrier layer is higher than the atomic percentage of cobalt in the first magnetic layer. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of magnesium. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of tungsten or tantalum oxide. In one or more of the foregoing and following embodiments, the bottom metal layer is made of tungsten or tantalum. In one or more of the foregoing and following embodiments, the thickness of the diffusion barrier layer is in the range of 0.1 nm to 0.6 nm. In one or more of the foregoing and following embodiments, the SOT magnetic device further includes an intermediate metal layer disposed between the spacer layer and the second magnetic layer. In one or more of the foregoing and following embodiments, the intermediate metal layer is made of magnesium, and the spacer layer is made of magnesium oxide. In one or more of the foregoing and following embodiments, the SOT magnetic device further includes a top metal layer disposed above the second magnetic layer. In one or more of the foregoing and following embodiments, the top metal layer is made of ruthenium. In one or more of the foregoing and following embodiments, the second magnetic layer comprises iron, cobalt, and boron.

[0059] According to another aspect of the present invention, a spin-orbit torque (SOT) magnetic device includes: a bottom metal layer; a first magnetic layer disposed above the bottom metal layer; a spacer layer disposed above the first magnetic layer; and a second magnetic layer disposed above the spacer layer. A magnetic dead layer is disposed between the bottom metal layer and the first magnetic layer, and a diffusion barrier layer for inhibiting the diffusion of metal elements from the first magnetic layer into the bottom metal layer is disposed between the magnetic dead layer and the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer includes iron and cobalt. In one or more of the foregoing and following embodiments, the diffusion barrier layer includes iron, and the atomic percentage of iron in the diffusion barrier layer is higher than the atomic percentage of iron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer and the diffusion barrier layer further include boron. In one or more of the foregoing and following embodiments, the atomic percentage of boron in the diffusion barrier layer is higher than the atomic percentage of boron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer is Fe. x Co y B 1-x-y And the diffusion barrier layer is Fe z B 1-zWhere z > x. In one or more of the foregoing and following embodiments, 0.50 ≤ x ≤ 0.70 and 0.65 ≤ z ≤ 0.90. In one or more of the foregoing and following embodiments, the diffusion barrier layer comprises cobalt, and the atomic percentage of cobalt in the diffusion barrier layer is higher than the atomic percentage of cobalt in the first magnetic layer. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of magnesium. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of tungsten or tantalum oxide. In one or more of the foregoing and following embodiments, the bottom metal layer is made of tungsten or tantalum. In one or more of the foregoing and following embodiments, the thickness of the diffusion barrier layer is in the range of 0.1 nm to 0.6 nm. In one or more of the foregoing and following embodiments, the SOT magnetic device further includes an intermediate metal layer disposed between the spacer layer and the second magnetic layer. In one or more of the foregoing and following embodiments, the intermediate metal layer is made of magnesium, and the spacer layer is made of magnesium oxide. In one or more of the foregoing and following embodiments, the SOT magnetic device further includes a top metal layer disposed above the second magnetic layer. In one or more of the foregoing and following embodiments, the top metal layer is made of ruthenium. In one or more of the foregoing and following embodiments, the second magnetic layer comprises iron, cobalt, and boron.

[0060] According to another aspect of the present invention, a magnetic memory includes a SOT magnetic device and a switching element. The SOT magnetic device includes: a bottom metal layer; a first magnetic layer disposed above the bottom metal layer; a spacer layer disposed above the first magnetic layer; and a second magnetic layer disposed above the spacer layer. The switching element is coupled to either the bottom metal layer or the second magnetic layer. A diffusion barrier layer for suppressing the diffusion of metal elements from the first magnetic layer into the bottom metal layer is disposed between the bottom metal layer and the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer includes iron and cobalt. In one or more of the foregoing and following embodiments, the diffusion barrier layer includes iron, and the atomic percentage of iron in the diffusion barrier layer is higher than the atomic percentage of iron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer and the diffusion barrier layer further include boron. In one or more of the foregoing and following embodiments, the atomic percentage of boron in the diffusion barrier layer is higher than the atomic percentage of boron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer is Fe. x Co y B 1-x-y The diffusion barrier layer is Fe z B 1-zWhere z > x. In one or more of the foregoing and following embodiments, 0.50 ≤ x ≤ 0.70 and 0.65 ≤ z ≤ 0.90. In one or more of the foregoing and following embodiments, the diffusion barrier layer comprises cobalt, and the atomic percentage of cobalt in the diffusion barrier layer is higher than the atomic percentage of cobalt in the first magnetic layer. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of magnesium. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of tungsten or tantalum oxide. In one or more of the foregoing and following embodiments, the bottom metal layer is made of tungsten or tantalum. In one or more of the foregoing and following embodiments, the thickness of the diffusion barrier layer is in the range of 0.1 nm to 0.6 nm. In one or more of the foregoing and following embodiments, the SOT magnetic device further includes an intermediate metal layer disposed between the spacer layer and the second magnetic layer. In one or more of the foregoing and following embodiments, the intermediate metal layer is made of magnesium, and the spacer layer is made of magnesium oxide. In one or more of the foregoing and following embodiments, the SOT magnetic device further includes a top metal layer disposed above the second magnetic layer. In one or more of the foregoing and following embodiments, the top metal layer is made of ruthenium. In one or more of the foregoing and following embodiments, the second magnetic layer comprises iron, cobalt, and boron.

[0061] According to one aspect of the present invention, in a method of manufacturing a spin-orbit torque (SOT) magnetic device, a first magnetic layer is formed over a bottom metal layer. A spacer layer is formed over the first magnetic layer. A second magnetic layer is formed over the spacer layer. Furthermore, a diffusion barrier layer is formed between the first magnetic layer and the bottom metal layer. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by thermal annealing performed after the formation of the first magnetic layer. In one or more of the foregoing and following embodiments, the process temperature of the thermal annealing is in the range of 350°C to 450°C. In one or more of the foregoing and following embodiments, the process time of the thermal annealing is in the range of 30 minutes to 240 minutes. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by plasma treatment performed on the first magnetic layer after its formation. In one or more of the foregoing and following embodiments, at least one plasma of argon, nitrogen, and hydrogen is used in the plasma treatment. In one or more of the foregoing and following embodiments, the process time of the plasma treatment is in the range of 1 minute to 60 minutes. In one or more of the foregoing and following embodiments, the first magnetic layer comprises iron and cobalt, the diffusion barrier layer comprises iron, and the atomic percentage of iron in the diffusion barrier layer is higher than the atomic percentage of iron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer and the diffusion barrier layer further comprise boron. In one or more of the foregoing and following embodiments, the atomic percentage of boron in the diffusion barrier layer is higher than the atomic percentage of boron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer is Fe. x Co y B 1-x-y The diffusion barrier layer is Fe z B 1-z Where z > x. In one or more of the foregoing and following embodiments, 0.50 ≤ x ≤ 0.70 and 0.65 ≤ z ≤ 0.90. In one or more of the foregoing and following embodiments, the first magnetic layer comprises iron and cobalt, the diffusion barrier layer comprises cobalt, and the atomic percentage of cobalt in the diffusion barrier layer is higher than the atomic percentage of cobalt in the first magnetic layer. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by a deposition process. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of magnesium. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of tungsten or tantalum oxide. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by oxidation of the bottom metal layer. In one or more of the foregoing and following embodiments, the bottom metal layer is made of tungsten or tantalum, and the diffusion barrier layer is made of tungsten or tantalum oxide. In one or more of the foregoing and following embodiments, the thickness of the diffusion barrier layer is in the range of 0.1 nm to 0.6 nm.

[0062] According to another aspect of the present invention, in a method of manufacturing an SOT magnetic device, a diffusion barrier layer is formed above a bottom metal layer. A first magnetic layer is formed above the diffusion barrier layer. A spacer layer is formed above the first magnetic layer. An intermediate metal layer is formed above the spacer layer. A second magnetic layer is formed above the intermediate metal layer. The diffusion barrier layer inhibits the diffusion of metal elements from the first magnetic layer into the bottom metal layer during a subsequent thermal process exceeding 450°C. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by thermal annealing performed after the formation of the first magnetic layer. In one or more of the foregoing and following embodiments, the process temperature of the thermal annealing is in the range of 350°C to 450°C. In one or more of the foregoing and following embodiments, the process time of the thermal annealing is in the range of 30 minutes to 240 minutes. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by plasma treatment performed on the first magnetic layer after its formation. In one or more of the foregoing and following embodiments, at least one plasma of argon, nitrogen, and hydrogen is used in the plasma treatment. In one or more of the foregoing and following embodiments, the process time of the plasma treatment is in the range of 1 minute to 60 minutes. In one or more of the foregoing and following embodiments, the first magnetic layer comprises iron and cobalt, the diffusion barrier layer comprises iron, and the atomic percentage of iron in the diffusion barrier layer is higher than the atomic percentage of iron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer and the diffusion barrier layer further comprise boron. In one or more of the foregoing and following embodiments, the atomic percentage of boron in the diffusion barrier layer is higher than the atomic percentage of boron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer is Fe. x Co y B 1-x-y The diffusion barrier layer is Fe z B 1-zWhere z > x. In one or more of the foregoing and following embodiments, 0.50 ≤ x ≤ 0.70 and 0.65 ≤ z ≤ 0.90. In one or more of the foregoing and following embodiments, the first magnetic layer comprises iron and cobalt, the diffusion barrier layer comprises cobalt, and the atomic percentage of cobalt in the diffusion barrier layer is higher than the atomic percentage of cobalt in the first magnetic layer. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by a deposition process. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of magnesium. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of tungsten or tantalum oxide. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by oxidation of the bottom metal layer. In one or more of the foregoing and following embodiments, the bottom metal layer is made of tungsten or tantalum, and the diffusion barrier layer is made of tungsten or tantalum oxide. In one or more of the foregoing and following embodiments, the thickness of the diffusion barrier layer is in the range of 0.1 nm to 0.6 nm.

[0063] According to another aspect of the invention, in a method of manufacturing an SOT magnetic device, a first magnetic layer is formed over a bottom metal layer. The first magnetic layer is processed such that a diffusion barrier layer is formed between the bottom metal layer and the first magnetic layer. A spacer layer is formed over the first magnetic layer. An intermediate metal layer is formed over the spacer layer. A second magnetic layer is formed over the intermediate metal layer. The diffusion barrier layer inhibits the diffusion of metal elements from the first magnetic layer into the bottom metal layer during a subsequent thermal process exceeding 450°C. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by thermal annealing performed after the formation of the first magnetic layer. In one or more of the foregoing and following embodiments, the process temperature of the thermal annealing is in the range of 350°C to 450°C. In one or more of the foregoing and following embodiments, the process time of the thermal annealing is in the range of 30 minutes to 240 minutes. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by plasma treatment performed on the first magnetic layer after its formation. In one or more of the foregoing and following embodiments, at least one plasma of argon, nitrogen, and hydrogen is used in the plasma treatment. In one or more of the foregoing and following embodiments, the plasma treatment process time ranges from 1 minute to 60 minutes. In one or more of the foregoing and following embodiments, the first magnetic layer comprises iron and cobalt, the diffusion barrier layer comprises iron, and the atomic percentage of iron in the diffusion barrier layer is higher than the atomic percentage of iron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer and the diffusion barrier layer further comprise boron. In one or more of the foregoing and following embodiments, the atomic percentage of boron in the diffusion barrier layer is higher than the atomic percentage of boron in the first magnetic layer. In one or more of the foregoing and following embodiments, the first magnetic layer is Fe. x Coy B 1-x-y The diffusion barrier layer is Fe z B 1-z Where z > x. In one or more of the foregoing and following embodiments, 0.50 ≤ x ≤ 0.70 and 0.65 ≤ z ≤ 0.90. In one or more of the foregoing and following embodiments, the first magnetic layer comprises iron and cobalt, the diffusion barrier layer comprises cobalt, and the atomic percentage of cobalt in the diffusion barrier layer is higher than the atomic percentage of cobalt in the first magnetic layer. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by a deposition process. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of magnesium. In one or more of the foregoing and following embodiments, the diffusion barrier layer is made of tungsten or tantalum oxide. In one or more of the foregoing and following embodiments, the diffusion barrier layer is formed by oxidation of the bottom metal layer. In one or more of the foregoing and following embodiments, the bottom metal layer is made of tungsten or tantalum, and the diffusion barrier layer is made of tungsten or tantalum oxide. In one or more of the foregoing and following embodiments, the thickness of the diffusion barrier layer is in the range of 0.1 nm to 0.6 nm.

[0064] The foregoing outlines features of several embodiments to enable those skilled in the art to better understand aspects of the invention. Those skilled in the art should understand that they can readily use this invention as a basis to design or modify other processes and structures for implementing the same purposes and / or achieving the same advantages as the embodiments described herein. Those skilled in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of the invention, and that various changes, substitutions, and modifications can be made to them herein without departing from the spirit and scope of the invention.

Claims

1. A magnetic random access memory (MRAM), comprising: Bottom metal layer; A first magnetic layer is disposed above the bottom metal layer; A spacer layer is disposed above the first magnetic layer; A second magnetic layer is disposed above the spacer layer; A diffusion barrier layer is disposed between the bottom metal layer and the first magnetic layer; as well as A magnetic dead layer is disposed between the diffusion barrier layer and the bottom metal layer and is in direct contact with the diffusion barrier layer.

2. The magnetic random access memory according to claim 1, wherein, The diffusion barrier layer and the first magnetic layer comprise the same elements, and the atomic percentage of the same elements in the diffusion barrier layer is higher than the atomic percentage of the same elements in the first magnetic layer.

3. The magnetic random access memory according to claim 2, wherein, The same element is at least one of iron, cobalt, or boron.

4. The magnetic random access memory according to claim 2, wherein, The same elements are iron and boron.

5. A magnetic random access memory (MRAM), comprising: Support layer; A bottom metal layer is disposed on the support layer; A first magnetic layer is disposed above the bottom metal layer; A spacer layer is disposed above the first magnetic layer; A second magnetic layer is disposed above the spacer layer; A layer, made of one of magnesium, tungsten oxide, tantalum, or tantalum oxide, is disposed between the bottom metal layer and the first magnetic layer and is in direct contact with the bottom metal layer and the first magnetic layer.

6. The magnetic random access memory according to claim 5, wherein, The layer contains an oxide of tungsten or tantalum.

7. The magnetic random access memory according to claim 5, wherein, The thickness of the layer is in the range of 0.1 nm to 0.6 nm.

8. A method for manufacturing a spin orbital torque (SOT) magnetic device, the method comprising: A diffusion barrier layer is formed on the bottom metal layer; A first magnetic layer is formed on the diffusion barrier layer; A spacer layer is formed on the first magnetic layer; as well as A second magnetic layer is formed on the spacer layer. The diffusion barrier layer comprises an oxide formed by directly oxidizing the bottom metal layer.

9. The method according to claim 8, wherein, The thickness of the diffusion barrier layer is in the range of 0.1 nm to 0.6 nm.

10. The method according to claim 8, wherein, The diffusion barrier layer is formed by thermal oxidation, plasma oxidation, or chemical oxidation.

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