A novel doping process to refine grain size for smoother BiSb film surfaces.

Abstract

The present disclosure generally relates to a spin-orbit torque (SOT) magnetic tunnel junction (MTJ) device comprising a doped bismuth antimonide (BiSbE) layer having a (012) orientation. The device may include a magnetic write head, a read head, or an MRAM device. The dopants in the BiSbE layer reinforce the (012) orientation. The BiSbE layer may be formed on a texturing layer to ensure the (012) orientation, and a migration barrier may be formed on the BiSbE layer to ensure that antimony does not migrate through the structure and contaminate other layers. A buffer layer and an interlayer may also be present. The buffer layer and the interlayer may each independently be a single layer of material or multiple layers of material. The buffer layer and the interlayer further promote the (012) orientation of the doped BiSbE layer while suppressing the migration of antimony (Sb) into the doped BiSbE layer and improving the homogeneity of the doped BiSbE layer.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 292,582, filed December 22, 2021.

[0002] FIELD OF THEINVENTION Embodiments of the present disclosure generally relate to doped bismuth antimonide (BiSbE) layers having a (012) orientation, where E is a dopant, for use as a topological insulator. [Background technology]

[0003] 2. Description of Related Art BiSb with (012) orientation is a narrow-gap topological insulator that possesses both a giant spin Hall effect and high electrical conductivity. BiSb is a material that has been proposed in various spin-orbit torque (SOT) applications, such as magnetoresistive random access memory (MRAM) devices and spin Hall layers for energy-assisted magnetic recording (EAMR) write heads.

[0004] However, BiSb materials have not yet been adopted for commercial SOT applications due to several obstacles: they have a low melting point, large grain size, significant Sb migration issues during thermal annealing due to film roughness, difficulty in maintaining the (012) orientation for maximum spin Hall effect, and are generally soft and easily damaged by ion milling.

[0005] Therefore, there is a need for improved SOT devices and processes that form BiSb layers with smaller grain size and (012) orientation that reduce film roughness and thereby reduce Sb migration problems. Summary of the Invention

[0006] The present disclosure generally relates to a spin-orbit torque (SOT) magnetic tunnel junction (MTJ) device comprising a doped bismuth antimonide (BiSbE) layer having a (012) orientation. The device may include a magnetic write head, a read head, or an MRAM device. The dopants in the BiSbE layer reinforce the (012) orientation. The BiSbE layer may be formed on a texturing layer to ensure the (012) orientation, and a migration barrier may be formed on the BiSbE layer to ensure that antimony does not migrate through the structure and contaminate other layers. A buffer layer and an interlayer may be present. The buffer layer and the interlayer may each independently be a single layer of material or multiple layers of material. The buffer layer and the interlayer each include at least one of a tetragonal (001) material, a tetragonal (110) material, a body-centered cubic (bcc) (100) material, a face-centered cubic (fcc) (100) material, a textured bcc (100) material, a textured fcc (100) material, a textured (100) material, or an amorphous metal material. The buffer layer and the interlayer further promote the (012) orientation of the doped BiSbE layer while suppressing antimony (Sb) migration into the doped BiSbE layer and improving the homogeneity of the doped BiSbE layer.

[0007] In another embodiment, a spin-orbit torque (SOT) device comprises a substrate and a doped bismuth antimonide (BiSbE) layer disposed over the substrate, the doped BiSbE layer having a (012) orientation, E is a dopant, and the dopant is present in an amount between about 0.5 atomic percent and about 5 atomic percent of the doped BiSbE layer.

[0008] In another embodiment, a spin-orbit torque (SOT) device comprises a substrate, a doped bismuth antimony (BiSbE) layer disposed over the substrate, the doped BiSbE layer having a (012) orientation, where E is a dopant, an interlayer disposed over the doped BiSbE layer, and a magnetic tunnel junction (MTJ) stack disposed over the interlayer.

[0009] In another embodiment, a method of forming a spin-orbit torque (SOT) device includes disposing a substrate in a sputtering chamber, the sputtering chamber including a sputtering target; flowing a sputtering gas into the sputtering chamber, the sputtering gas including an inert gas and a non-reactive dopant gas; applying a bias to the sputtering target; and depositing a doped bismuth antimony (BiSbE) layer on the substrate, where E is a dopant from the dopant gas, and the doped BiSbE layer has a (012) orientation.

[0010] In one embodiment, a method of forming a spin-orbit torque (SOT) device includes disposing a substrate in a sputtering chamber, flowing a sputtering gas into the chamber, the sputtering gas including a non-reactive dopant gas, applying a bias to a sputtering target, and depositing a bismuth antimony (BiSb) layer on the substrate, the BiSb layer being doped with the non-reactive dopant gas.

[0011] In another embodiment, a spin-orbit torque (SOT) device comprises a substrate and a bismuth antimony dopant (BiSbE) layer on the substrate, the BiSbE layer having a (012) orientation, the BiSbE layer comprising bismuth, antimony, and a non-reactive element, the non-reactive dopant element comprising between about 0.5 atomic % and about 5 atomic % of the BiSbE layer.

[0012] In yet another embodiment, a method of forming a spin-orbit torque (SOT) device includes disposing a substrate in a sputter chamber, depositing a seed layer over the substrate, and depositing a bismuth antimony (BiSb) layer over the seed layer, where depositing the BiSb layer includes providing a sputtering gas including an inert gas, such as Ar, Ne, Kr, Xe, or a combination thereof. The sputtering gas can also be N2, H2, C x H y where x and y are numbers, and combinations thereof. The method also includes depositing an interlayer over the doped BiSb layer.

[0013] In yet another embodiment, a spin-orbit torque (SOT) magnetic tunnel junction (MTJ) MRAM device may be formed according to the above-mentioned method, the SOT MTJ device including a substrate, a buffer layer formed on the substrate, the buffer layer including a first intermediary layer, the first intermediary layer including a material selected from the group of tetragonal texture (001), (110) material, texture bcc or B2 (100) material, texture fcc (100) material, texture (100) material, or amorphous metal material, and a bismuth antimony (BiSb) layer having a (012) orientation formed using the above-mentioned method on the buffer layer, the BiSb layer including a tri-layer structure including a first Bi layer, the BiSb layer disposed on the first Bi layer, and the second Bi layer disposed on the BiSb layer, the buffer layer configured to reduce Sb migration into the BiSb layer.

[0014] In yet another embodiment, a spin-orbit torque (SOT) magnetic tunnel junction (MTJ) MRAM device may be formed according to the method described above, the SOT MTJ device comprising: a substrate; a buffer layer formed on the substrate, the buffer layer comprising a textured layer having a (100) orientation; and a first intermediate layer disposed on the textured layer, the first intermediate layer being composed of a material selected from the group consisting of tetragonal (001), tetragonal (110), texture bcc or B2 (100), texture fcc (100), and combinations thereof; a bismuth antimony (BiSb) layer formed on the buffer layer using the method described above, the BiSb layer having a (012) orientation, the buffer layer configured to reduce diffusion of Sb into the BiSb layer; and an interlayer disposed on the BiSb layer. [Brief description of the drawings]

[0015] So that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the present disclosure, briefly summarized above, can be made by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be considered as limiting its scope, as the present disclosure may admit of other equally effective embodiments. [Figure 1] FIG. 1 is a schematic diagram of a particular embodiment of a magnetic media drive including a read / write head having a SOT MTJ device. [Diagram 2] FIG. 2 is a partial cross-sectional side view of a particular embodiment of a read / write head having a SOT MTJ device. [Figure 3A] FIG. 1 is a schematic cross-sectional view of a particular embodiment of an SOT device having a BiSbE layer with a (012) orientation, forming an SOT-based MRAM device. [Figure 3B]FIG. 1 is a schematic cross-sectional view of a particular embodiment of an SOT device having a BiSbE layer with a (012) orientation that forms part of or a component of an SOT-based energy-assisted magnetic recording (EAMR) write head used for magnetic recording. [Figure 3C] 3C illustrates an exemplary multi-layer structure of buffer layers and / or interlayers that may be used with the SOT MTJ device of FIGS. 3A and 3B, according to various embodiments. [Figure 3D] 3C illustrates an exemplary multi-layer structure of buffer layers and / or interlayers that may be used with the SOT MTJ device of FIGS. 3A and 3B, according to various embodiments. [Figure 3E] 3C illustrates an exemplary multi-layer structure of buffer layers and / or interlayers that may be used with the SOT MTJ device of FIGS. 3A and 3B, according to various embodiments. [Figure 3F] 3C illustrates an exemplary multi-layer structure of buffer layers and / or interlayers that may be used with the SOT MTJ device of FIGS. 3A and 3B, according to various embodiments. [Figure 3G] FIG. 4 is a schematic cross-sectional view of a BiSbE layer with sublayers, which may be the BiSbE layer of the SOT MTJ device of FIGS. 3A and 3B, according to one embodiment. [Figure 4] 1 is a flow chart illustrating a method of forming a doped BiSbE layer. [Diagram 5] 1 shows Glow Discharge Spectrometry (GDS) estimated concentrations of elements in BiSb and BiSbE films versus sputter time in seconds. [Figure 6] 1 shows 2θ XRD scans for the intensity of the BiSb orientation in a BiSb layer and a BiSbE layer doped with N2. [Figure 7] 13 shows 2θ XRD scans of logarithm of intensity of the BiSb orientation for a BiSb stack and a N2-doped BiSbE stack. [Figure 8A] 4 shows the c / a ratio versus temperature for a BiSb layer and a BiSbE layer doped with N2 (BiSbN). [Figure 8B]1 shows a table containing film properties of BiSb and BiSbN coupons at various annealing temperatures. [Figure 8C] 1 shows a table containing film properties of BiSb and BiSbN coupons at various annealing temperatures. [Figure 9A] 1 shows an RMS roughness chart comparing a BiSb layer with a N2 doped BiSbE layer. [Figure 9B] 9B shows a roughness summary table for the RMS roughness chart of FIG. 9A. [Figure 9C] 1 shows the conductivity versus thickness for various BiSb films. [Figure 10A] 2 is a schematic cross-sectional view of a SOT device for use in a MAMR write head, such as a read / write head of the drive of FIG. 1 or other suitable media drive. [Figure 10B] FIG. 10B is a schematic MFS diagram of a particular embodiment of a portion of a MAMR write head with the SOT device of FIG. [Figure 10C] FIG. 10B is a schematic MFS diagram of a particular embodiment of a portion of a MAMR write head with the SOT device of FIG. [Figure 11] FIG. 1 is a schematic cross-sectional view of a SOT MTJ used as an MRAM device. [Figure 12A] FIG. 2 is a schematic media facing surface (MFS) diagram of a pinned, doped BiSbE-based sensor according to various embodiments. [Figure 12B] FIG. 2 is a schematic media facing surface (MFS) diagram of a pinned, doped BiSbE-based sensor according to various embodiments.

[0016] To facilitate understanding, the same reference numbers have been used, whenever possible, to designate identical elements common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific mention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] In the following, reference will be made to embodiments of the present disclosure. However, it should be understood that the present disclosure is not limited to the specifically described embodiments. Instead, any combination of the following features and elements, whether associated with different embodiments or not, is contemplated to implement and practice the present disclosure. Furthermore, although embodiments of the present disclosure may achieve advantages over other possible solutions and / or over the prior art, whether or not a particular advantage is achieved by a given embodiment does not limit the present disclosure. Thus, the following aspects, features, embodiments, and advantages are merely illustrative and are not considered elements or limitations of the appended claims unless expressly recited in the claims. Similarly, references to "the present disclosure" are not to be construed as a generalization of any inventive subject matter disclosed herein, and should not be considered elements or limitations of the appended claims unless expressly recited in the claims.

[0018] Embodiments of the present disclosure generally relate to a buffer layer that promotes the maintenance of a bismuth antimony (BiSb) layer with a (012) orientation. Antimony (Sb) is highly reactive, and the buffer layer provides a low-reactivity medium that reduces chemical interaction between the BiSb layer and external materials while promoting the growth of BiSb in the (012) orientation. The configuration of the buffer layer reduces migration of Sb into the BiSb layer.

[0019] The (012) oriented BiSb layer has a large spin Hall angle effect and high electrical conductivity. The (012) oriented BiSb layer can be used to form a spin-orbit torque (SOT) magnetic tunnel junction (MTJ) device. For example, the (012) oriented BiSb layer can be used as a spin Hall layer in a spin-orbit torque device in a magnetic recording head, for example as part of a read head and / or a microwave assisted magnetic recording (MAMR) write head. In another example, the (012) oriented BiSb layer can be used as a spin Hall electrode layer in a magnetoresistive random access memory (MRAM) device. The SOT MTJ device can be in a vertical stack configuration or an in-plane stack configuration. The SOT MTJ device can be utilized in, for example, read and / or write heads, MRAM, artificial intelligence chips, and other applications. The (012) oriented BiSb layer stack has a higher spin Hall angle and higher performance in a SOT MTJ device than the (001) oriented BiSb layer.

[0020] The embodiments of the present disclosure generally relate to a bismuth antimonide (BiSb) layer having a (012) orientation doped with a non-reactive gas for use as a topological insulator. In one embodiment, a spin-orbit torque device includes a substrate and a doped BiSbE layer on the substrate, the BiSbE layer having a (012) orientation, the BiSbE layer including bismuth, antimony, and a dopant. The dopant may be N2, H2, C x H y where x and y are numbers, and combinations thereof. In another embodiment, a method of forming an SOT device includes depositing a substrate in a sputtering chamber, flowing a sputtering gas into the chamber, the sputtering gas comprising a non-reactive gas, applying a bias to a sputtering target, and depositing a bismuth antimony (BiSb) layer on the substrate.

[0021] 1 is a schematic diagram of a particular embodiment of a disk drive 100 including a read / write head having a SOT MTJ device. Such a magnetic media drive may be a single drive or may comprise multiple drives. For purposes of illustration, a single disk drive 100 according to a particular embodiment is shown. As shown, at least one rotatable magnetic disk 112 is supported on a spindle 114 and rotated by a drive motor 118. The magnetic recording on each magnetic disk 112 is in the form of any suitable pattern of data tracks, such as an annular pattern of concentric data tracks (not shown) on the magnetic disk 112.

[0022] At least one slider 113 is positioned near the magnetic disk 112, with each slider 113 supporting one or more magnetic head assemblies 121 including a SOT device. As the magnetic disk 112 rotates, the slider 113 moves radially in and out above the disk surface 122 so that the magnetic head assemblies 121 can access different tracks of the magnetic disk 112 on which desired data is written. Each slider 113 is attached to an actuator arm 119 by a suspension 115. The suspension 115 provides a slight spring force that biases the slider 113 toward the disk surface 122. Each actuator arm 119 is attached to an actuator means 127. The actuator means 127 as shown in FIG. 1 can be a voice coil motor (VCM). The VCM includes a coil movable within a fixed magnetic field, and the direction and speed of the coil movement are controlled by motor current signals provided by a control unit 129.

[0023] During operation of disk drive 100, the rotation of magnetic disk 112 creates an air bearing between slider 113 and disk surface 122, which exerts an upward force, or lift, on slider 113. The air bearing thus counteracts the slight spring force of suspension 115 and supports slider 113 a small, substantially constant distance away from and slightly above disk surface 122 during normal operation.

[0024] The various components of disk drive 100 are controlled by control signals generated by control unit 129, such as access control signals and internal clock signals. Typically, control unit 129 includes logic control circuits, storage means, and a microprocessor. Control unit 129 generates control signals for controlling various system operations, such as drive motor control signals on line 123 and head position and seek control signals on line 128. The control signals on line 128 provide desired current profiles to optimally move and position slider 113 to the desired data track on magnetic disk 112. Write and read signals are communicated to and from write and read heads on magnetic head assembly 121 by recording channel 125.

[0025] The above description of a typical magnetic media drive, and the accompanying illustration of Figure 1, are for representation purposes only. It will be apparent that a magnetic media drive may include multiple media or disks and actuators, and each actuator may support several sliders.

[0026] It should be understood that the embodiments discussed herein are applicable to data storage devices such as hard disk drives (HDDs), as well as tape drives such as tape embedded drives (TEDs) or insertable tape media drives such as those conforming to the LTO (Linear Tape Open) standard. An exemplary TED is described in U.S. Patent No. 10,991,390, entitled "Tape Embedded Drive," issued on April 27, 2021 and assigned to the same assignee as the present application, which is incorporated herein by reference. Thus, references in the detailed description to HDDs or tape drives are merely for illustrative purposes and are not intended to limit the disclosure unless expressly claimed. For example, references to disk media in HDD embodiments are provided by way of example only and can be substituted for tape media in tape drive embodiments. Additionally, references or claims to magnetic recording devices or data storage devices are intended to include at least both HDDs and tape drives, unless HDDs or tape drive devices are expressly claimed.

[0027] 2 is a partial cross-sectional side view of a particular embodiment of a read / write head 200 having a SOT MTJ device. The read / write head 200 faces the magnetic disk 112. The read / write head 200 may correspond to the magnetic head assembly 121 shown in FIG. The read / write head 200 includes a medium facing surface (MFS) 212, such as a gas bearing surface, facing the magnetic disk 112, a write head 210, and a magnetic read head 211. As shown in FIG. 2, the magnetic medium 112 moves past the write head 210 in the direction indicated by arrow 232, and the read / write head 200 moves in the direction indicated by arrow 234.

[0028] In some embodiments, the magnetic read head 211 is a magnetoresistive (MR) read head including an MTJ sensing element 204 located between MR shields S1 and S2. In other embodiments, the magnetic read head 211 is a magnetic tunnel junction (MTJ) read head including an MTJ sensing element 204 located between MR shields S1 and S2. The magnetic fields of adjacent magnetized regions in the magnetic disk 112 are detectable by the MR (or MTJ) sensing element 204 as recorded bits. Various embodiments of the SOT MTJ device may be incorporated into the read head 211.

[0029] Examples of differential SOT readers are described in U.S. patents entitled "SOT Differential Reader and Method of Making Same", i.e., U.S. Patent No. 11,100,946, filed July 1, 2020, and "SOT Film Stack for differential Reader", i.e., U.S. Patent No. 11,094,338, filed September 23, 2020, each of which is assigned to the same assignee as the present application and is incorporated by reference herein.

[0030] Examples of single SOT readers are described in U.S. patents entitled "Magnetic Sensor Using Spin Hall Effect," U.S. Pat. No. 10,720,570, filed November 29, 2017, and "Magnetic Sensor Using Inverse Spin Hall Effect," U.S. Pat. No. 9,947,347, filed December 20, 2016, each of which is assigned to the same assignee as the present application and is incorporated herein by reference.

[0031] In an embodiment where the write head is a MAMR-based write head, the MAMR write head 210 includes a main pole 220, a leading shield 206, a trailing shield 240, a spin-orbit torque (SOT) device 250, and a coil 218 that excites the main pole 220. The coil 218 may have a "pancake" structure that wraps around the back contact between the main pole 220 and the trailing shield 240 instead of the "spiral" structure shown in FIG. 2. The SOT element 250 is formed in a gap 254 between the main pole 220 and the trailing shield 240. The main pole 220 includes a trailing taper 242 and a leading taper 244. The trailing taper 242 extends from a recessed position to the MFS 212. The leading taper 244 extends from a recessed position to the MFS 212. The trailing taper 242 and the leading taper 244 may have the same degree of taper, the degree of taper being measured relative to the longitudinal axis 260 of the main pole 220. In some embodiments, the main pole 220 does not include the trailing taper 242 and the leading taper 244. Instead, the main pole 220 includes a trailing side (not shown) and a leading side (not shown), where the trailing side and the leading side are substantially parallel. The main pole 220 may be a magnetic material, such as an FeCo alloy. The leading shield 206 and the trailing shield 240 may be a magnetic material, such as a NiFe alloy. In certain embodiments, the trailing shield 240 may include a trailing shield hot seed layer 241. The trailing shield hot seed layer 241 may include a high momentum sputter material such as CoFeN or FeXN, where X is selected from the group consisting of Rh, Al, Ta, Zr, Ni, Co, W, Hf, Re, and Ti, and combinations thereof. In certain embodiments, the trailing shield 240 does not include a trailing shield hot seed layer.

[0032] FIG. 3A is a schematic cross-sectional view of a particular embodiment of an SOT MTJ device 300 having a doped bismuth antimonide (BiSbE) layer 304 with a (012) crystal orientation forming an SOT-based device.

[0033] The SOT MTJ device 300 includes a substrate 311, a seed or buffer layer 310 on the substrate 311, a doped BiSbE layer 304 on the substrate, an interlayer 320 on the doped BiSbE layer 304, an MTJ structure 323 including a free perpendicular magnetic anisotropy (PMA) layer 324 on the interlayer 320, an insulating layer 325 on the free PMA layer 324, and a reference PMA layer 327 on the insulating layer 325, and a cap layer 328 on the reference PMA layer 327.

[0034] In one embodiment, the seed or buffer layer 310 of the SOT MTJ device 300 comprises an amorphous adjustment layer 314 on a substrate layer 311 and a grown B2 or bcc(100) texturing layer 316 on the amorphous adjustment layer 314. The amorphous adjustment layer 314 is composed of one or more alloys of elements selected from the group consisting of Ni, Fe, Co, Zr, W, Ta, Hf, Ag, Pt, Pd, Si, Ge, Mn, Al, Ti, and combinations thereof. Exemplary alloys include alloys selected from the group consisting of NiTa, NiFeTa, CoHf, CoFeHf, NiW, NiFeW, CoHfB, CoFeB, CoZrTa, NiFeB, CoB, FeB, and combinations of alloys thereof. The bcc texturing (100) layer 316 may be a material selected from the group consisting of B2 RuAl phase, heated (temperature 100C-300C) CrX alloys (where X=Ru, Mo, W, and Ti≦10 at.%), other B2 phase materials such as NiAl or RhAl, and combinations thereof.

[0035] The BiSbE layer 304 of the SOT MTJ device 300 includes bismuth (Bi), antimony (Sb), and a dopant element (E). To form the top BiSbE layer 304, the sputtering gas includes an inert gas such as Ar, Ne, Kr, Xe, or a combination thereof, and may include N2, H2, C2O, or ZnO. x H y (where x and y are numbers), as well as non-reactive dopant gases such as , , and combinations thereof are provided. The SOT MTJ device 300 may be used in the MAMR write head of the disk drive 100 of FIG. 1, the read and / or write head 200 of FIG. 2, or other suitable magnetic media drives. The doped BiSbE layer is used as a topological insulator, such as in an SOT-based MRAM device or an SOT-based EAMR read or write head. The doped BiSbE layer may include multiple BiSb lamellae layers and one or more doped lamellae layers. The doped BiSbE layer has a (012) orientation. In certain embodiments, the doped BiSbE layer has a higher annealing temperature, stronger (012) texture, smaller grain size, and / or smaller surface roughness compared to undoped BiSb material.

[0036] The interlayer 320 of the SOT MTJ device 300 may have a similar structure to the seed layer or buffer layer 310 described above. Additionally, the interlayer 320 may include materials similar to those used for the seed layer or buffer layer 310. The interlayer 320 includes an fcc(100) texturing layer 326 and a texturing layer 318 disposed on the fcc(100) texturing layer 326. In one embodiment, the fcc(100) texturing layer 326 may function as a migration barrier to prevent Sb migration from the doped BiSbE layer 304. The (100) texturing layer 316, the amorphous adjustment layer 314, the texturing layer 318, and the fcc(100) texturing layer 326 described above each have a lattice constant in the range of about 4.10 Å to about 4.70 Å (shown in FIG. 3F). As will be described below, the interlayer 320 may alternatively comprise a (001) tetragonal layer 318 (shown in Figures 3E and 3F).

[0037] The free PMA layer 324 of the SOT MTJ device 300 comprises one or more stacks selected from the group consisting of Co / Pt (i.e., a bilayer of cobalt and platinum, where " / " is used herein to denote a bilayer), Co / Pd, Co / Ni, and combinations thereof. Alternatively, the free PMA layer 324 may comprise one or more layers selected from the group consisting of CoFeB, FePt, other PMA-derived layers, and combinations thereof. An insulating layer 325, such as a MgO layer, is formed over the free PMA layer 324.

[0038] The reference PMA layer 327 of the SOT MTJ device 300 comprises one or more stacks selected from the group consisting of Co / Pt, Co / Pd, Co / Ni, and combinations thereof. Alternatively, the reference PMA layer 327 may comprise one or more layers selected from the group consisting of CoFeB, FePt, other PMA-inducing layers, and combinations thereof. The reference PMA layer 327 may include one or more synthetic antiferromagnetic (SAF) pinning structures. The magnetic orientation of the reference PMA layer 327 may be set at an annealing temperature of about 260° C. or greater for 2 hours or greater.

[0039] The cap layer 328 of the SOT MTJ device 300 comprises a material selected from the group consisting of NiFe, SiN, TiN, Al2O3, SiO2, NiFeTa, NiTa, NiW, NiFeW, CoHf, CoFeHf, Pt, Co, Cu, Ni, NiCu, CoCu, Ru, Ta, Cr, Au, Rh, CoFe CoFeB, other non-magnetic materials, other magnetic materials, and combinations thereof.

[0040] It should be understood that an undoped SOT device may be formed in the same manner as described above (ie, layer 304 comprises BiSb with no dopants).

[0041] It should further be appreciated that multiple SOT MTJ devices 300 may be configured together as part of a memory cell array, with the BiSbE layer 304 being the spin orbital material electrode. A top electrode (not shown) may be disposed over the reference PMA layer 327. Each of the memory cells may be part of a two-terminal device or a three-terminal device. The spin orbital material electrode and the top electrode may function as a bit line, a word line, a read word line, a write word line, and combinations thereof. The memory cell array may be implemented as a cross-point array or other architecture.

[0042] 3B is a schematic cross-sectional view of a particular embodiment of an SOT MTJ device 302 having a doped BiSbE layer 304 with a (012) crystallographic orientation that forms a portion or component of an SOT-based EAMR (e.g., MAMR) write head used for magnetic recording. The doped BiSbE layer 304 of the SOT MTJ device 302 is the same as the doped BiSbE layer 304 of the SOT MTJ device 300. The SOT MTJ device 302 may be used in a read / write head of the disk drive 100 of FIG. 1 or other suitable magnetic media drive, or in the read / write head 200 of FIG. 2.

[0043] 3A, but now a spin torque layer (STL) 323 is formed on top of the interlayer 320. The STL 323 includes a ferromagnetic material selected from the group consisting of CoFe, CoIr, NiFe, CoFeM, where M is a material selected from the group consisting of B, Ta, Re, Ir, and combinations thereof.

[0044] A charge current through the doped BiSbE layer 304 acting as a spin Hall layer generates a spin current in the doped BiSbE layer 304. Spin-orbit coupling between the doped BiSbE layer 304 and the STL 323 causes the switching or precession of the magnetization of the STL 323 by the spin current from the doped BiSbE layer 304. The switching or precession of the magnetization of the STL 323 can generate an assisting AC and / or DC magnetic field from the main pole of a write head used in magnetic recording to the write field. The SOT-based EAMR element has multiple times greater power efficiency compared to spin-transfer torque (STT)-based MAMR elements.

[0045] 3C-3G show example multi-layer structures of a buffer layer 310 and / or an interlayer 320 that may be used with the SOT MTJ device 300 of FIG. 3A and the SOT MTJ device 302 of FIG. 3B, according to various embodiments.

[0046] The embodiments of Figures 3C-3G may be used in combination with each other and are not an exclusive list of possible buffer layers 310 and / or interlayers 320. Additionally, although each of Figures 3C-3G describes both a buffer layer 310 and an interlayer 320, the buffer layer 310 and interlayer 320 may have different configurations or different amounts of sublayers or intermediate layers, such as amorphous adjustment layer 314, texturing layer 316, texturing layer 318, and fcc(100) texturing layer 326 (see Figures 3C-3F), to allow better strain relaxation and enhance or promote (012) growth in the doped BiSbE layer 304. In certain embodiments, the buffer layer 310 and / or interlayer 320 are deposited by physical vapor deposition (PVD), such as sputtering, molecular beam epitaxy, ion beam deposition, other suitable PVD processes, and combinations thereof. Additionally, the buffer layer 310 may be a single layer of crystalline or amorphous material and the interlayer 320 may be a multi-layer structure. As discussed in more detail below, the seed or buffer layer 310 or the interlayer 320 may be a textured fcc(111) single layer or multi-layer fcc(111) stack material with a lattice constant of about 3.48 angstroms (Å) to 3.71 Å.

[0047] 3C, in one embodiment, the seed or buffer layer 310 and / or interlayer 320 comprises a first interlayer 330 and a second interlayer 332 disposed on the first interlayer 330. In one embodiment, the first interlayer 330 comprises a metallic amorphous material and the second interlayer 332 comprises a tetragonal (001) or (110) material. In another embodiment, the first interlayer 330 comprises a metallic amorphous material and the second interlayer 332 comprises a textured bcc (100) or B2 material.

[0048] With reference to FIG. 3D, in one embodiment, the buffer layer 310 and / or the interlayer 320 comprises a first interlayer 330, a second interlayer 332 disposed on the first interlayer 330, and a third interlayer 334 disposed on the second interlayer 332. The first interlayer 330 comprises a metallic amorphous material, and the second interlayer 332 comprises a textured bcc(100) or B2 material. In one embodiment, the third interlayer 334 comprises a textured bcc(100) or B2 material. In another embodiment, the third interlayer 334 comprises a fcc(100) material. In yet another embodiment, the third interlayer 334 comprises a tetragonal (001) material.

[0049] 3E, in one embodiment, the buffer layer 310 and / or the interlayer 320 comprises a first interlayer 330, a second interlayer 332 disposed on the first interlayer 330, a third interlayer 334 disposed on the second interlayer 332, and a fourth interlayer 336 disposed on the third interlayer 334. The first interlayer 330 comprises a metallic amorphous material, and the second interlayer 332 comprises a textured bcc(100) or B2 material. In one embodiment, the third interlayer 334 comprises a textured bcc(100) or B2 material, and the fourth interlayer 336 comprises a fcc(100) material. In another embodiment, the third interlayer 334 comprises a textured bcc(100) or B2 material, and the fourth interlayer 336 comprises a tetragonal(110) material. In yet another embodiment, the third interlayer 334 comprises a textured bcc(100) or B2 material and the fourth interlayer 336 comprises a tetragonal (001) material.

[0050] With reference to FIG. 3F, in one embodiment, the buffer layer 310 and / or interlayer 320 comprises a first intermediate layer 330, where the first intermediate layer 330 comprises a metallic amorphous material, a second intermediate layer 332 comprising a bcc(100) or B2 material texture, a third intermediate layer 334 comprising a bcc(100) or B2 material texture, a fourth intermediate layer 336 comprising a tetragonal (001) material, and a fifth intermediate layer 338 comprising an fcc(100) material.

[0051] The amorphous metal material of the first intermediate layer 330 of FIG. 3F may include one or more elements selected from the group consisting of Ni, Fe, Co, Zr, W, Ta, Hf, Ag, Pt, Pd, Si, Ge, Mn, Al, Ti, and combinations thereof. Additionally or alternatively, the first intermediate layer 330 may include one or more compounds selected from the group consisting of NiTa, NiFeTa, NiNb, NiW, NiFeW, NiFeHf, CoHfB, CoZrTa, CoFeB, NiFeB, CoB, FeB, and combinations of alloys thereof. Furthermore, the amorphous metal material may have a nearest neighbor (XRD) diffraction peak, the d-spacing of which is about 2.0 Å to about 2.2 Å.

[0052] The textured bcc(100) or B2 materials of the second 332 and third 334 interlayers may be similar or different. For B2 materials, the materials may be selected from the group consisting of B2 phase RuAl alone or in combination with other B2 phases such as NiAl and RhAl, Cr at temperatures above 150°C, or heated CrX alloys (where X=Ru, Mo, W, or Ti≦10 at. % and heated to 100-300°C). For textured bcc(100) materials, the materials may be selected from the group consisting of V, Nb, Mo, W, Ta, WTi. 50, Cr, alloy combinations thereof, and alloy combinations thereof with one or more additional elements selected from the group consisting of Ti, Al, Ge, Si, Ag, Cu, Mn, Pd, Pt, Ni, Co, Fe, and combinations thereof. Additionally, the textured bcc(100) or B2 material may have an a-axis lattice constant of about 2.88 Å to 3.31 Å.

[0053] The tetragonal (001) or (110) material of the fourth intermediate layer 336 of Figure 3F can have an a-axis in the range of about 4.2 Å to about 4.7 Å and a c-axis in the range of about 2.88 Å to about 3.15 Å. The tetragonal (001) or (110) material can be selected from the group consisting of SbO2, TiO2, IrO2, RuO2, CrO2, VO2, OsO2, RhO2, PdO2, WVO4, CrNbO4, SnO2, GeO2, composites thereof, alloys thereof, and alloys thereof with one or more additional elements selected from the group consisting of W, Nb, and combinations thereof.

[0054] The fcc(100) material of the fifth intermediate layer 338 of Figure 3F can have a lattice constant in the range of about 4.10 A to about 4.70 A. The fcc(100) material can be selected from the group consisting of Ag, Al, Au, FeO, CoO, ZrO, MgO, TiO, ScN, TiN, NbN, ZrN, HfN, TaN, ScC, TiC, NbC, ZrC, HfC, TaC, WC, and combinations thereof, alloys thereof, and combinations of alloys thereof with one or more additional elements selected from the group consisting of W, Al, Ag, W, Mo, Zr, Ti, Ge, Si, and combinations thereof.

[0055] In certain embodiments described above, the buffer layer 310 and / or the interlayer 320 are deposited by physical vapor deposition (PVD), such as by sputtering, molecular beam epitaxy, ion beam deposition, other suitable PVD processes, or combinations thereof.

[0056] FIG. 3G is a schematic cross-sectional view of an undoped BiSb layer 340 with sublayers that can replace the doped BiSbE layer 304 of the SOT MTJ device 300, 302 of FIG. 3A and FIG. 3B according to one embodiment. FIG. 3G illustrates the advantage of sandwiching a BiSb (or doped BiSbE) layer between Bi layers. The Bi layer acts as a composition modulation layer to ultimately make the composition depth more uniform for either the undoped or doped form of BiSb. After deposition and / or annealing, Sb has a tendency to migrate to the interface of the undoped BiSb or doped BiSbE layer. A thin Bi layer on either side of the undoped BiSb or doped BiSbE layer can capture any Sb that may migrate from the undoped BiSb or doped BiSbE layer, thus reducing the large composition gradient that may occur during deposition and / or after annealing. A thin Bi layer can be grown on undoped BiSb or doped BiSbE or used as a seed layer for an undoped BiSb or doped BiSbE layer to improve compositional modulation in SOT MTJ devices while still promoting (012) growth.

[0057] The undoped BiSb layer 340 of FIG. 3G comprises a Bi stack 304a, 304c. The first Bi sublayer 304a is disposed on the buffer layer 310. The BiSb sublayer 304b is disposed on the first Bi sublayer 304a. The BiSb sublayer 304b can include Sb at an atomic percentage between about 10% and about 20%. The second Bi sublayer 304c is disposed on the BiSb sublayer 304b. In some embodiments, the first and second Bi sublayers 304a, 304c each have a thickness of about 10 Å or less and function as a composition modulation sublayer to improve thickness composition uniformity.

[0058] The undoped BiSb layer 340 of FIG. 3G has a (012) orientation. In some embodiments, the undoped BiSb layer 340 comprises Bi1-xSbx where 0 < x < 1. In certain embodiments, the undoped BiSb layer 340 comprises Bi1-xSbx where 0.05 < x < 0.2 or comprises antimony with an atomic percent content of from about 7% to about 22%.

[0059] FIG. 4 is a flowchart showing a method 400 of forming a doped BiSbE layer. The doped BiSbE layer can be the doped BiSbE layer 304 in the SOT MTJ device 300 of FIG. 3A or the doped BiSbE layer 304 of the SOT MTJ device 302 of FIG. 3B. The SOT MTJ devices 300 and 302 can be used as part of an MRAM cell in the read / write head of the disk or other suitable magnetic media drive of FIG. 1 or the read and / or write head of FIG. 2.

[0060] In 402 of method 400, a substrate is disposed within a sputtering chamber. The substrate can be the substrate 311 of FIG. 3A or FIG. 3B. In 404 of method 400, the sputtering chamber is evacuated until a base pressure is reached. In 406 of method 400, a sputtering gas is delivered into the sputtering chamber. To form the doped BiSbE layer, the sputtering gas includes an inert gas such as Ar, Ne, Kr, Xe, or a combination thereof. The sputtering gas may also include a non-reactive dopant gas such as N2, H2, C x H y (where x and y are numbers), and combinations thereof. In some embodiments, the sputtering gas includes a mixing ratio of 1:1 inert gas to non-reactive dopant gas. In other embodiments, the sputtering gas includes a mixing ratio of 1:2 inert gas to non-reactive dopant gas.

[0061] At 408 of the method 400, a bias is applied to a sputtering target disposed in a sputter chamber, the sputter target being a material (e.g., BiSb) to be deposited on a substrate. At 410 of the method 400, a doped BiSbE layer is deposited on the substrate. The doped BiSbE layer contains elements of a non-reactive dopant gas.

[0062] FIG. 5 shows the Glow Discharge Spectroscopy (GDS) sputter time in seconds versus GDS estimated concentrations, which are the approximate atomic percent (at.%) of various elements in undoped and doped BiSbE films. Undoped BiSb films and N2-doped and doped BiSbE films were measured for the presence of Sb, Bi, carbon (C), and N2. N2-doped and doped BiSbE films had detectable levels of N2 up to about 4-5 at. %. However, undoped BiSb films show no detectable N2 in the films. The presence of N2 in doped BiSbE films is desirable because N2 reduces the grain size of the film during its formation, thus promoting (012) growth.

[0063] 6 shows 2θ XRD scans of the logarithm of the intensity of the (012) peak of a first doped BiSbE layer 610 and an undoped BiSb layer 620. The doped BiSbE layer is doped with nitrogen. The doped BiSbE layer 610 has a thickness of about 100 Å and is doped with about 1-4 atomic % N2. The undoped BiSb layer 620 has a thickness of about 100 Å.

[0064] Due to the N2 doping of the doped BiSbE layer 610, the doped BiSbE layer 610 has a smoother film texture compared to the undoped BiSb layer 620 because during the formation of the doped BiSbE layer 610, the dopant gas interrupts the grain growth in the doped BiSbE layer 610, thereby reducing the grain size of the crystals of the doped BiSbE layer 610 and resulting in a smoother surface for improved topological insulator (TI) performance (i.e., the grain size of the doped BiSbE layer 610 is smaller than that of the undoped BiSb layer 620). The smaller grain size of the doped BiSbE layer 610 results in increased reflectivity at the desired peaks (012) and (024) and decreased reflectivity at the undesired peaks (104), (110), (202), and (116).

[0065] 7 shows 2θ XRD scans of the intensity of the BiSb orientation for two stacks 710 and 720. The stack 710 includes a seed layer of NiTa-silicide layer formed to a thickness of about 60 Å, an undoped BiSb layer formed to a thickness of about 100 Å, a NiFe layer formed to a thickness of about 15 Å, an interlayer of NiTa formed to a thickness of about 60 Å, and a cap layer of NiCr formed to a thickness of about 30 Å. The stack 720 includes a seed layer of NiTa-silicide layer formed to a thickness of about 60 Å, a doped BiSbE layer, such as the BiSbE layer 304 of FIGS. 3A and 3B, formed to a thickness of about 100 Å, a NiFe layer formed to a thickness of 15 Å, an interlayer of NiTa formed to a thickness of about 60 Å, and a cap layer of NiCr formed to a thickness of about 30 Å. The dopant for the doped BiSbE layer is nitrogen. It should be noted that stacks 710 and 720 are not the MTJ, seed layer, interlayer structures of Figures 3A and 3B, but rather are simple stacks that demonstrate the advantages of using doped BiSbE layers rather than undoped BiSb layers. The doped BiSbE layers include multiple BiSb lamellae layers and multiple dopant lamellae layers. Although the dopant is shown to be nitrogen, it should be understood that other dopants, such as hydrogen, are contemplated.

[0066] Similar to FIG. 6, doping the BiSbE layer with a non-reactive gas such as N2 results in a smaller grain size (i.e., the grain size of stack 720 is smaller than that of stack 710), so stack 720 has a smoother film texture compared to stack 610. The smaller grain size of the doped stack 720 results in increased reflectivity at the desired peaks (012) and (024) and decreased reflectivity at the undesired peaks (003), (104), and (006). As shown by the dashed line, the (012) peak is significantly higher and more pronounced for stack 720 compared to stack 710, and the only difference between stack 710 and stack 720 is the doped BiSbE layer in stack 720, while stack 710 has an undoped BiSb layer.

[0067] FIG. 8A shows the c-axis lattice constant to a-axis lattice constant (c / a) ratio versus temperature for an undoped BiSb layer and a doped BiSbE layer doped with N, such as the doped BiSbE layer 304 of FIG. 3A and FIG. 3B. With respect to FIG. 8A, it should be noted that the undoped BiSb layer and the doped BiSbE layer are simply the layers themselves without the other layers of the MTJ SOT described above. Although the c / a ratio of a perfect crystal is a constant value, distortion of the crystal lattice can change the c / a ratio. The change in the c / a ratio can make the crystal lattice more suitable for a desired seed layer. Thus, by manipulating the c / a ratio, a lattice that promotes smoother film growth of a (012) oriented BiSb layer can be achieved.

[0068] As shown in FIG. 8A, eight coupons, four coupons of undoped BiSb samples and four coupons of doped BiSbE samples doped with N2, were annealed at various temperatures ranging from 185 degrees Celsius (°C) to 250°C. The undoped BiSb coupons may comprise the SOT MTJ device 300 of FIG. 3A or the SOT MTJ device 302 of FIG. 3B. The undoped BiSb coupons were formed in a chamber using a Kr sputtering gas with a flow rate of 5 sccm. The doped BiSbE coupons were formed in a chamber using a mixture of Kr and N2 sputtering gases. One example of this embodiment was formed in a chamber using a 1:2 Kr:N2 sputtering gas mixture (i.e., the Kr flow rate was 5 sccm and the N2 flow rate was 10 sccm). In other embodiments, the sputtering mixture may be a 1:1 mixture of Kr and N2 (e.g., Kr flow rate equal to 5 sccm and non-reactive doping gas flow rate equal to 5 sccm). Comparing the BiSb coupon to the N2-doped BiSbE coupon, it can be seen that the N2-doped BiSbE film (BiSbN) has a significantly lower c / a ratio compared to the undoped BiSb film. A more detailed analysis of the c / a ratio and additional film properties is discussed below in Figures 8B and 8C.

[0069] FIG. 8B shows a chart including the data points of FIG. 8A as well as additional undoped BiSb and doped BiSbE film properties at specific annealing temperatures. Films were selected from the thickness range of 100-130 Å, which is most sensitive to changes in surface conduction state. Coupon S1-5, an undoped BiSb film, and coupon S2-1, an N2 doped BiSbE film, were annealed at a temperature of 185° C. for 60 minutes. The c / a ratio of S1-5 was 2.703 and that of S2-1 was 2.656. Coupon S1-6, an undoped BiSb film, and coupon S2-5, an N2 doped BiSbE film, were annealed at a temperature of 195° C. for 60 minutes. The c / a ratio of S1-5 was 2.710 and that of S2-1 was 2.652. The coupon S1-1, which is an undoped BiSb film, and the coupon S2-2, which is an N2-doped BiSbE film, were annealed at a temperature of 225° C. for 60 minutes. The c / a ratio of S1-5 was 2.708, and that of S2-1 was 2.660. The coupon S1-3, which is an undoped BiSb film, and the coupon S2-3, which is an N2-doped BiSbE film, were annealed at a temperature of 250° C. for 75 minutes. The c / a ratio of S1-5 was 2.710, and that of S2-1 was 2.674. Thus, as shown in FIG. 8A and FIG. 8B, the c / a ratio was significantly decreased in the doped BiSbE coupons (S2-1, S2-5, S2-2, S2-3) compared to the undoped BiSb coupons (S1-5, S1-6, S1-4, S1-3). For example, N-doped BiSbE coupons S2-1, S2-5, S2-2, and S2-3 each had a c / a ratio less than 2.7, while undoped BiSb coupons S1-5, S1-6, S1-4, and S1-3 each had a c / a ratio greater than 2.7.

[0070] FIG. 8C shows a chart containing the properties of undoped and doped BiSbE films before and after annealing at various temperatures to determine if doping the undoped BiSb film adversely affects the TI characteristics and makes the doped BiSbE film thermally unstable. To test the thermal stability of the doped BiSbE film, eight coupons, four coupons of undoped BiSb samples (S13-S16) and four coupons of doped BiSbE samples (S21-25), were analyzed for change in resistance (Rs Delta / Mean) before and after annealing at various temperatures. Both the undoped BiSb coupons (S13-S16) and the doped BiSbE coupons (S21-25) were found to have experienced a change in resistance of approximately -5% to +5%, which is within the normal standard error range (i.e., no mathematically significant change in resistance was observed in the samples after annealing). Thus, doping BiSbE films with N2 during formation is effective in reducing grain size and improving film texture while also retaining thermal stability.

[0071] FIG. 9A shows a root mean square (RMS) roughness chart comparing an undoped BiSb layer to a doped BiSbE layer doped with N2, such as the doped BiSbE layer 304 of FIGS. 3A and 3B. Slots 7-11 each represent an undoped BiSb layer having a particular thickness. Slots 2-6 correspond to doped BiSbE layers formed under process conditions of 750 V / 150 mA with a sputtering gas of 5 sccm Kr (Kr5) and 10 sccm N2 (N10). Slots 7-11 correspond to undoped BiSb layers formed under similar process conditions of 750 V / 150 mA with a sputtering gas of 5 sccm Kr (Kr5) (i.e., the sputtering gas did not contain a non-reactive dopant gas). FIG. 9B shows a roughness summary table for the RMS roughness chart of FIG. 9A.

[0072] With respect to slots 2 and 7, both slot 2 and slot 7 were formed with a deposition time of 300 seconds (s), but slot 7 having a thickness of about 576 angstroms (Å) is thicker than slot 2 having a thickness of about 488 Å. This is because the undoped BiSb layer in slot 7 was deposited at a faster rate of about 1.92 Å / s compared to the doped BiSbE layer in slot 2, which had a deposition rate of about 1.627 angstroms per second (Å / s). Additionally, slot 7 having an RMS roughness of 14.28 is rougher than slot 2 having an RMS roughness of 3.92.

[0073] With regard to slots 3 and 8, both slot 3 and slot 8 were formed with a deposition time of 240 seconds, but slot 8 with a thickness of 481 Å is thicker than slot 3 with a thickness of 404 Å. This is because the undoped BiSb layer in slot 8 was deposited at a faster rate of about 2.004 Å / s compared to the doped BiSbE layer in slot 3, which had a deposition rate of about 1.683 Å / s. Additionally, slot 8 with an RMS roughness of 13.33 is rougher than slot 3 with an RMS roughness of 3.03.

[0074] With regard to slots 4 and 9, both slot 4 and slot 9 were formed with a deposition time of 180 seconds, but slot 9 with a thickness of 350 Å is thicker than slot 4 with a thickness of 298 Å. This is because the undoped BiSb layer in slot 9 was deposited at a faster rate of about 1.944 Å / s compared to the doped BiSbE layer in slot 4, which had a deposition rate of about 1.656 Å / s. Additionally, slot 9 with an RMS roughness of 8.89 is rougher than slot 4 with an RMS roughness of 2.24.

[0075] With respect to slots 5 and 10, both slot 5 and slot 10 were formed with a deposition time of 120 seconds, but slot 10, having a thickness of 236 Å, is thicker than slot 5, having a thickness of 198 Å. This is because the undoped BiSb layer in slot 10 was deposited at a faster rate of about 1.967 Å / s compared to the doped BiSbE layer in slot 5, which had a deposition rate of about 1.650 Å / s. Additionally, slot 10, having an RMS roughness of 5.31, is rougher than slot 4, having an RMS roughness of 1.27.

[0076] With regard to slots 6 and 11, both slots 6 and 11 were formed with a deposition time of 60 seconds, but slot 11, having a thickness of 125 Å, is thicker than slot 6, having a thickness of 102 Å. This is because the undoped BiSb layer in slot 11 was deposited at a faster rate of about 2.083 Å / s compared to the doped BiSbE layer in slot 6, which had a deposition rate of about 1.700 Å / s. Additionally, slot 11, having an RMS roughness of 1.21, is rougher than slot 6, having an RMS roughness of 0.78.

[0077] Thus, it is clearly shown that N2 doping reduces both the film thickness and grain size by interrupting the continuous growth of the BiSb grains, resulting in slower growing films with lower RMS roughness, thereby improving the interface quality between the BiSb layer and the surrounding layers and suppressing undesirable antimony migration.

[0078] FIG. 9C shows the conductivity versus film thickness for various BiSb film types (i.e., both undoped and doped). The conductivity (1 / resistivity (ρ)*1000) of five different BiSb film types was measured, with each of the five different BiSb film types having five coupons of various thicknesses. For each of the five different BiSb film types, one coupon had a deposition time of 300 seconds, a second coupon had a deposition time of 240 seconds, a third coupon had a deposition time of 180 seconds, a fourth coupon had a deposition time of 120 seconds, and a fifth coupon had a deposition time of 60 seconds. Thus, each of the five coupons for each of the five different BiSb films had various thicknesses because process conditions such as deposition time, annealing temperature, V / mA, and the presence of dopant elements during the formation of the film affect the thickness of the film, as discussed above.

[0079] "Old BiSb Data" shows the conductivity vs. film thickness for undoped BiSb films of the prior art. "101821BiSb Data Kr" shows the conductivity vs. film thickness for undoped BiSb coupons in slots 6-11 of Figures 9A and 9B. "101821BiSbN Data Kr" shows the conductivity vs. film thickness for N2 doped BiSbE coupons in slots 1-5 of Figures 9A and 9B. The doped BiSbE coupons show an increase in bulk conductivity without affecting TI.

[0080] 10A is a schematic cross-sectional view of an SOT device 1000 for use in a MAMR write head, which may be used, for example, as part of a read / write head in the drive 100 of FIG. 1 or other suitable magnetic media drive. The SOT device 1000 includes a doped BiSbE layer 304 having a (012) orientation formed on a seed layer 310 formed on a substrate 311, such as the N-doped BiSbE layer 304 and seed layer 310 of FIGS. 3A and 3B. A spin torque layer (STL) 1097 is formed on the BiSbE layer 304. The STL 1097 includes a ferromagnetic material, such as one or more layers of CoFe, CoIr, NiFe, and CoFeX alloys, where X=B, Ta, Re, or Ir.

[0081] In certain embodiments, a current shunt blocking layer 1096 is disposed between the BiSbE layer 304 and the STL 1097. The current shunt blocking layer 1096 reduces current flow from the BiSbE layer 304 to the STL 1097, but allows spin-orbit coupling between the BiSbE layer 304 and the STL 1097. In certain embodiments, the current shunt blocking layer 1096 includes a magnetic material that provides greater spin-orbit coupling between the BiSbE layer 304 and the STL 1097 than a non-magnetic material. In certain embodiments, the current shunt blocking layer 1096 comprises FeCo, FeCoM, FeCoMO, FeCoMMeO, FeCoM / MeO multilayer stack, FeCoMNiMnMgZnFeO, FeCoM / NiMnMgZnFeO multilayer stack, multiple layers / stacks thereof, or combinations thereof, where M is one or more of B, Si, P, Al, Hf, Zr, Nb, Ti, Ta, Mo, Mg, Y, Cu, Cr, and Ni, and Me is one or more of Si, Al, Hf, Zr, Nb, Ti, Ta, Mg, Y, or Cr. In certain embodiments, the current shunt blocking layer 1096 is formed to a thickness of about 10 Å to about 100 Å. In certain aspects, a current shunt blocking layer 1096 having a thickness greater than 100 Å may reduce spin-orbit coupling between the BiSbE layer 304 and the STL 1097. In certain embodiments, a current shunt blocking layer having a thickness less than 10 Å may not sufficiently reduce current flow from the BiSbE layer 304 to the STL1097.

[0082] In certain embodiments, additional layers, such as a spacer layer 1098 and a pinned layer 1099, are formed over the STL 1097. The pinned layer 1099 can partially pin the STL 1097. The pinned layer 1099 comprises a single layer or multiple layers of PtMn, NiMn, IrMn, IrMnCr, CrMnPt, FeMn, other antiferromagnetic materials, or combinations thereof. The spacer layer 1098 comprises a single layer or multiple layers of magnesium oxide, aluminum oxide, other non-magnetic materials, or combinations thereof.

[0083] 10B and 10C are schematic MFS diagrams of a particular embodiment of a portion of a MAMR write head 210 having the SOT device 1000 of FIG. 10A. The MAMR write head 210 may be the write head of FIG. 2 or any other suitable write head in the disk drive 100 of FIG. 1 or any other suitable magnetic media drive, such as a tape drive. The MAMR write head 210 includes, in the track direction, a main pole 220 and a trailing shield 240. The SOT device 1000 is disposed in the gap between the main pole and the trailing shield 240.

[0084] In operation, a charge current through the doped BiSbE layer or layer stack 304, which acts as a spin Hall layer, generates a spin current in the doped BiSbE layer. Spin-orbit coupling between the BiSbE layer and the STL 1097 causes switching or precession of the magnetization of the STL 1097 due to spin-orbit coupling of the spin current from the BiSbE layer 304. The switching or precession of the magnetization of the STL 1097 can generate an assisting AC and / or DC magnetic field for the write field. The energy-assisted write head based on SOT has several times greater power efficiency compared to the MAMR write head based on spin-transfer torque. As shown in FIG. 10B, the easy axis of the magnetization direction of the STL 1097 is perpendicular to the MFS from the shape anisotropy of the STL 1097, from the pinned layer 1099 of FIG. 10A, and / or from the hard bias element close to the STL 1097. As shown in FIG. 10C, the easy axis of magnetization of the STL 1097 is parallel to the MFS from the shape anisotropy of the STL 1097, from the pinned layer 1099 of FIG. 10A, and / or from hard bias elements proximate to the STL 1097.

[0085] 11 is a schematic cross-sectional view of a SOT MTJ 1101 used as an MRAM device 1100. The MRAM device 1100 includes a reference layer (RL) 1110, a spacer layer 1120 on the RL 1110, a recording layer 1130 on the spacer layer 1120, a seed layer or buffer layer 310 on a current shunt blocking layer 1140 disposed on the recording layer 1130, and a doped BiSbE layer or layer stack 304 on the seed layer or buffer layer 310. The doped BiSbE layer 304 and the seed layer or buffer layer 310 may be the doped BiSbE layer 304 and the seed layer 310 of FIG. 3A and FIG. 3B.

[0086] The RL 1110 comprises a single layer or multiple layers of CoFe, other ferromagnetic materials, and combinations thereof. The spacer layer 1120 comprises a single layer or multiple layers of magnesium oxide, aluminum oxide, other dielectric materials, or combinations thereof. The recording layer 1130 comprises a single layer or multiple layers of CoFe, NiFe, other ferromagnetic materials, or combinations thereof.

[0087] As mentioned above, in certain embodiments, the current shunt blocking layer 1140 is disposed between the seed or buffer layer 310 and the recording layer 1130. The current shunt blocking layer 1140 reduces current flow from the doped BiSbE layer 304 to the recording layer 1130, but allows spin-orbit coupling between the doped BiSbE layer 304 and the recording layer 1130. For example, writing to an MRAM device may be enabled by spin-orbit coupling between the doped BiSbE layer and the recording layer 1130, which allows switching of the magnetization of the recording layer 1130 by spin-orbit coupling of the spin current from the doped BiSbE layer 304. In certain embodiments, the current shunt blocking layer 1140 includes a magnetic material that provides greater spin-orbit coupling between the doped BiSbE layer 304 and the recording layer 1130 than a non-magnetic material. In certain embodiments, the current shunt blocking layer 1140 comprises FeCoM, FeCoMO, FeCoMMeO, FeCoM / MeO stack, FeCoMNiMnMgZnFeO, FeCoM / NiMnMgZnFeO stack, multiple layers / stacks thereof, or combinations thereof, where M is one or more of B, Si, P, Al, Hf, Zr, Nb, Ti, Ta, Mo, Mg, Y, Cu, Cr, and Ni, and Me is Si, Al, Hf, Zr, Nb, Ti, Ta, Mg, Y, or Cr.

[0088] The MRAM device 1100 of Figure 11 may include other layers such as pinning layers, pinning structures (e.g., synthetic antiferromagnetic (SAF) pinning structures), electrodes, gates, and other structures. Other MRAM devices than the structure of Figure 11 may be formed using a doped BiSbE layer 304 with a (012) orientation on top of the seed layer 310 to form the SOT MTJ 1101.

[0089] 12A and 12B are schematic medium-facing surface (MFS) diagrams of pinned, doped BiSbE-based sensors according to various embodiments. FIG. 12A shows a top pinned sensor 1202 including a first shield 1210a, a seed layer 1212 disposed adjacent to and in contact with the first shield 1210a, a doped BiSbE layer 1214 adjacent to and in contact with the seed layer 1212, an interlayer 1216 adjacent to and in contact with the doped BiSbE layer 1214, an MTJ structure 1218 adjacent to and in contact with the interlayer 1216, a capping layer 1220 disposed adjacent to and in contact with the MTJ structure 1218, and a second shield 1210b disposed adjacent to and in contact with the capping layer 1220. The sensor 1202 further comprises a first via 1230a and a second via 1230b, with a first insulating layer 1215a separating the first via 1230a from the interlayer 1216, the MTJ structure 1218, and the capping layer 1220, and a second insulating layer 1215b separating the second via 1230b from the interlayer 1216, the MTJ structure 1218, and the capping layer 1220.

[0090] 12B illustrates a bottom pinned sensor 1252. The sensor 1252 includes a first shield 1210a, a seed layer 1212 disposed adjacent to and in contact with the first shield 1210a, an MTJ structure 1218 disposed adjacent to and in contact with the seed layer 1212, a first interlayer 1216a disposed adjacent to and in contact with the MTJ structure 1218, a doped BiSbE layer 1214 disposed adjacent to and in contact with the first interlayer 1216a, a second interlayer 1216b disposed adjacent to and in contact with the doped BiSbE layer 1214, a capping layer 1220 disposed adjacent to and in contact with the second interlayer 1216b, and a second shield 1210b disposed adjacent to and in contact with the capping layer 1220.

[0091] Doping the BiSb layer with a non-reactive gas reduces grain size, improves film texture, and reduces undesirable antimony migration.

[0092] In one embodiment, a method of forming a spin-orbit torque (SOT) device includes disposing a substrate in a sputtering chamber, flowing a sputtering gas into the chamber, the sputtering gas including Kr gas and a non-reactive dopant gas, applying a bias to a target, and depositing a bismuth antimony (BiSb) layer on the substrate, the BiSb layer being doped with the non-reactive dopant gas. The non-reactive dopant gas doped BiSb layer includes between about 0.5 atomic % and about 5 atomic % of the non-reactive dopant gas. The non-reactive dopant gas doped BiSb layer is deposited at a rate between about 1.6 angstroms per second (Å / s) and about 1.7 Å / s. The method further includes depositing an interlayer on the BiSb layer, the interlayer including one or more materials selected from the group consisting of tetragonal (001) material, tetragonal (110) material, body-centered cubic (bcc) (100) material, face-centered cubic (fcc) (100) material, textured bcc (100) material, textured fcc (100) material, textured (100) material, amorphous material including covalently bonded carbides, oxides, or nitrides, amorphous metallic material, and layered combinations thereof. The sputtering gas into the chamber includes flowing a first volumetric flow rate of Kr gas into the chamber and flowing a second volumetric flow rate of a non-reactive dopant gas into the chamber. The non-reactive dopant gas includes N2, H2, Ne, Xe, Kr, C x H y where x and y are numbers, and combinations thereof. The first volumetric flow rate is substantially equal to the second volumetric flow rate. The first volumetric flow rate is less than the second volumetric flow rate.

[0093] In another embodiment, a spin-orbit torque (SOT) device comprises a substrate and a bismuth antimony dopant element (BiSbE) layer on the substrate, the BiSbE layer having a (012) orientation, the BiSbE layer including bismuth, antimony, and a non-reactive dopant element, the non-reactive dopant element constituting 0.5 atomic % to about 5 atomic % of the BiSbE layer. The BiSbE layer has a surface roughness of about 0.7 nanometers (nm) to about 4 nm. The BiSbE layer has a c / a ratio of less than 2.7. The BiSbE layer has a thickness of about 100 angstroms (Å) to about 500 Å. The BiSbE layer has a conductivity of about 1.2 1 / resistivity*1000 to about 1.4 1 / resistivity*1000. The BiSbE layer is deposited by doping the BiSbE layer with a non-reactive dopant gas, which is Kr, N2, H2, Xe, Ne, C x H y where x and y are numbers, and combinations thereof. The SOT device further comprises an intermediate layer disposed on the BiSbE layer, the intermediate layer comprising one or more materials selected from the group consisting of a tetragonal (001) material, a tetragonal (110) material, a textured B2 (100) material, a textured fcc (100) material, a textured bcc (100) material, an amorphous material, and layered combinations thereof.

[0094] In yet another embodiment, a method of forming a spin-orbit torque (SOT) device includes disposing a substrate in a sputter chamber; depositing a seed layer over the substrate; and depositing a bismuth antimony (BiSb) layer over the seed layer, wherein depositing the BiSb layer comprises any one of N2, H2, Ne, Xe, Kr, C x H ywhere x and y are numbers, and combinations thereof, and depositing an interlayer on the doped BiSb layer. The method further includes depositing a spin torque layer (STL) on the interlayer, the STL comprising a ferromagnetic material selected from the group consisting of CoFe, CoM, CoIr, NiFe, and CoFeM, and combinations thereof, where M is B, Ta, Re, or Ir. The method further includes depositing a free perpendicular magnetic anisotropy (PMA) layer on the interlayer, depositing an insulating layer on the PMA layer, depositing a reference PMA layer on the insulating layer, and depositing a cap layer on the reference PMA layer.

[0095] In yet another embodiment, a spin-orbit torque (SOT) magnetic tunnel junction (MTJ) MRAM device may be formed according to the above-mentioned method, the SOT MTJ device comprising: a substrate; a buffer layer formed on the substrate, the buffer layer comprising a first intermediate layer, the first intermediate layer comprising a material selected from the group of tetragonal texture (001), (110) material, texture bcc or B2 (100) material, texture fcc (100) material, and texture (100) material; and a bismuth antimony (BiSb) layer having a (012) orientation formed using the above-mentioned method on the buffer layer, the BiSb layer comprising a first Bi layer, the BiSb layer being disposed on the first Bi layer; and depositing a second Bi layer on the BiSb layer, the buffer layer being configured to reduce migration of Sb into the BiSb layer. The buffer layer further comprises an amorphous layer disposed under the first intermediate layer, the amorphous layer comprises a material selected from the group consisting of NiTa, NiFeTa, NiNb, NiW, NiFeW, NiFeHf, CoHfB, CoZrTa, CoFeB, NiFeB, CoB, FeB, and alloy combinations, the alloy combinations comprising a combination of elements selected from the group consisting of Ni, Fe, Co, Zr, W, Ta, Hf, Ag, Pt, Pd, Si, Ge, Mn, Al, and Ti. The SOT MTJ device, wherein the buffer layer further comprises a second intermediate layer. The second intermediate layer is a textured bcc(100) material. The second intermediate layer is a textured fcc(100) material. The SOT MTJ device further comprises an interlayer disposed on the BiSb layer, the interlayer comprises the same material as the first intermediate layer. The first and second Bi layers each have a width of about 0 Å to about 10 Å. The first intermediate layer is composed of a tetragonal (001) or (110) material, the tetragonal (001) or (110) material having an a-axis lattice constant in the range of about 4.20 Å to about 4.75 Å. The first intermediate layer is composed of an fcc(100) material, the fcc(100) material having a lattice constant in the range of about 4.10 Å to about 4.70 Å.

[0096] In yet another embodiment, a spin-orbit torque (SOT) magnetic tunnel junction (MTJ) MRAM device may be formed according to the method described above, the SOT MTJ device comprising: a substrate; a buffer layer formed on the substrate, the buffer layer comprising a textured layer having a (100) orientation; and a first intermediate layer disposed on the textured layer, the first intermediate layer being composed of a material selected from the group consisting of tetragonal (001), tetragonal (110), texture bcc or B2 (100), texture fcc (100), and combinations thereof; a bismuth antimony (BiSb) layer formed on the buffer layer using the method described above, the BiSb layer having a (012) orientation, the buffer layer configured to reduce diffusion of Sb in the BiSb layer; and an interlayer disposed on the BiSb layer. The buffer layer further comprises an amorphous layer including a material selected from the group consisting of NiTa, NiFeTa, NiNb, NiW, NiFeW, NiFeHf, CoHfB, CoZrTa, CoFeB, NiFeB, CoB, FeB, and alloy combinations, the alloy combinations including combinations of elements selected from the group consisting of Ni, Fe, Co, Zr, W, Ta, Hf, Ag, Pt, Pd, Si, Ge, Mn, Al, and Ti. The amorphous layer is disposed on the substrate, the texture layer is disposed on the amorphous layer, the first intermediate layer is disposed on the texture layer, and the BiSb layer is disposed on the first intermediate layer. The buffer layer further comprises a second intermediate layer, the second intermediate layer having a different cubic crystal structure from the first intermediate layer. The interlayer comprises one or more materials selected from the group consisting of tetragonal (001) material, tetragonal (110) material, textured B2 (100) material, textured fcc (100) material, textured bcc (100) material, amorphous material, and layered combinations thereof. The textured layer comprises a material selected from the group consisting of RuAl, Cr at a temperature of about 100° C. or greater, and a heated CrX alloy, where X is a material selected from the group consisting of Ru, W, Mo, and Ti, and X is heated to a temperature of 100° C. or greater.The first intermediate layer includes a tetragonal (001) or (110) material, and the tetragonal (001) or (110) material includes RuO2.

[0097] In another embodiment, a spin-orbit torque (SOT) device comprises a substrate and a doped bismuth antimonide (BiSbE) layer disposed over the substrate, the doped BiSbE layer having a (012) orientation, E is a dopant, and the dopant is present in an amount between about 0.5 atomic percent and about 5 atomic percent of the doped BiSbE layer. The SOT device is a write head. The SOT device is a read head. The SOT device is a magnetoresistive random access memory (MRAM) device. The doped BiSbE layer has a surface roughness between about 0.7 nm and about 4 nm. The dopants are selected from the group consisting of N2, H2, C x H y where x and y are numbers, and combinations thereof. Wherein the SOT device further comprises a seed layer disposed between the substrate and the doped BiSbE layer, the seed layer comprising an amorphous tuning layer and a texturing layer. The SOT device further comprises an interlayer disposed on the doped BiSbE layer, the interlayer comprising a migration barrier layer and a texturing layer. The SOT device further comprises a spin torque layer (STL) disposed on the doped BiSbE layer.

[0098] In another embodiment, a spin-orbit torque (SOT) device comprises a substrate, a doped bismuth antimony (BiSbE) layer disposed over the substrate, the doped BiSbE layer having a (012) orientation, and E being a dopant, an interlayer disposed over the doped BiSbE layer, and a magnetic tunnel junction (MTJ) stack disposed over the interlayer. The interlayer comprises at least one texturing layer and at least one migration barrier layer, the at least one migration barrier layer disposed over the doped BiSbE layer, and the MTJ stack disposed over the at least one texturing layer. The SOT device further comprises a seed layer disposed over the substrate, the doped BiSbE layer disposed over the seed layer. The seed layer comprises a textured fcc (111) layer. The seed layer has a lattice constant between about 3.48 Å and about 3.71 Å. The substrate is a main pole.The substrate is a magnetic shield.The SOT device further comprises a capping layer disposed on the MTJ stack.

[0099] In another embodiment, a method of forming a spin-orbit torque (SOT) device includes disposing a substrate in a sputtering chamber, the sputtering chamber including a sputtering target, flowing a sputtering gas into the sputtering chamber, the sputtering gas including an inert gas and a non-reactive dopant gas, applying a bias to the sputtering target, and depositing a doped bismuth antimony (BiSbE) layer on the substrate, where E is a dopant from the dopant gas, and the doped BiSbE layer has a (012) orientation. The method further includes forming a magnetic tunnel junction (MTJ) structure on the doped BiSbE layer, and forming a texturing layer and a migration barrier layer on the doped BiSbE layer, the substrate including an amorphous tuning layer. The method further includes forming a spin torque layer (STL) on the doped BiSbE layer, and forming a texturing layer and a migration barrier layer on the doped BiSbE layer, the substrate comprising an amorphous tuning layer.

[0100] While the above is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, which scope is determined by the following claims. The following items were included in the claims as originally filed: (Item 1) 1. A spin-orbit torque (SOT) device, comprising: A substrate; a doped bismuth antimony (BiSbE) layer disposed over the substrate, the doped BiSbE layer having a (012) orientation, E being a dopant, the dopant being present in an amount between about 0.5 atomic percent and about 5 atomic percent of the doped BiSbE layer. (Item 2) 2. The SOT device according to item 1, wherein the SOT device is a write head. (Item 3) Item 2. The SOT device according to item 1, wherein the SOT device is a read head. (Item 4) Item 2. The SOT device of item 1, wherein the SOT device is a magnetoresistive random access memory (MRAM) device. (Item 5) Item 2. The SOT device of item 1, wherein the doped BiSbE layer has a surface roughness of about 0.7 nm to about 4 nm. (Item 6) Item 2. The SOT device of item 1, wherein the dopant is selected from the group consisting of N2, H2, CxHy (wherein x and y are numbers), and combinations thereof. (Item 7) Item 1. The SOT device of item 1, further comprising a seed layer disposed between the substrate and the doped BiSbE layer, the seed layer comprising an amorphous adjustment layer and a texturing layer. (Item 8) Item 1. The SOT device of item 1, further comprising an interlayer disposed on the doped BiSbE layer, the interlayer comprising a migration barrier layer and a texturing layer. (Item 9) Item 1. The SOT device of item 1, further comprising a spin torque layer (STL) disposed on the doped BiSbE layer. (Item 10) A substrate; a doped bismuth antimonide (BiSbE) layer disposed over the substrate, the doped BiSbE layer having a (012) orientation, and E being a dopant; an interlayer disposed on the doped BiSbE layer; a magnetic tunnel junction (MTJ) stack disposed on the interlayer. (Item 11) Item 11. The SOT device of item 10, wherein the interlayer comprises at least one texturing layer and at least one migration barrier layer, the at least one migration barrier layer being disposed on the doped BiSbE layer, and the MTJ stack being disposed on the at least one texturing layer. (Item 12) Item 11. The SOT device of item 10, further comprising a seed layer disposed on the substrate, the doped BiSbE layer being disposed on the seed layer. (Item 13) Item 13. The SOT device of item 12, wherein the seed layer comprises a textured fcc(111) layer. (Item 14) Item 13. The SOT device of item 12, wherein the seed layer has a lattice constant of about 3.48 Å to about 3.71 Å. (Item 15) Item 11. The SOT device of item 10, wherein the substrate is a main pole. (Item 16) Item 11. The SOT device of item 10, wherein the substrate is a magnetic shield. (Item 17) Item 11. The SOT device of item 10, further comprising a capping layer disposed on the MTJ stack. (Item 18) Item 11. The SOT device of item 10, wherein the dopant is derived from a non-reactant dopant gas selected from the group consisting of N2, H2, CxHy (wherein x and y are numbers), and combinations thereof. (Item 19) 1. A method of forming a spin-orbit torque (SOT) device, comprising: disposing a substrate in a sputtering chamber, the sputtering chamber including a sputtering target; flowing a sputtering gas into the sputtering chamber, the sputtering gas including an inert gas and a non-reactive dopant gas; applying a bias to the sputtering target; depositing a doped bismuth antimonide (BiSbE) layer on the substrate, wherein E is a dopant from the dopant gas and the doped BiSbE layer has a (012) orientation. (Item 20) forming a magnetic tunnel junction (MTJ) structure on the doped BiSbE layer; 20. The method of claim 19, further comprising forming a texturing layer and a migration barrier layer on the doped BiSbE layer, wherein the substrate comprises an amorphous adjustment layer. (Item 21) forming a spin torque layer (STL) on the doped BiSbE layer; 20. The method of claim 19, further comprising forming a texturing layer and a migration barrier layer on the doped BiSbE layer, wherein the substrate comprises an amorphous adjustment layer. (Item 22) 20. The method of claim 19, wherein the non-reactive dopant gas is selected from the group consisting of N2, H2, CxHy (wherein x and y are numbers), and combinations thereof.

Claims

1. 1. A spin-orbit torque (SOT) device comprising: A substrate; a doped bismuth antimonide (BiSbE) layer disposed over the substrate, the doped BiSbE layer having a (012) orientation, E being a dopant, the dopant being present in an amount between about 0.5 atomic percent and about 5 atomic percent of the doped BiSbE layer; the dopant is selected from the group consisting of N2, H2, CxHy, where x and y are numbers, and combinations thereof; The doped BiSbE layer has a surface roughness of about 0.7 nm to about 4 nm.

2. The SOT device of claim 1 , wherein the SOT device is a write head.

3. The SOT device of claim 1 , wherein the SOT device is a read head.

4. The SOT device of claim 1 , wherein the SOT device is a magnetoresistive random access memory (MRAM) device.

5. 10. The SOT device of claim 1, further comprising a seed layer disposed between the substrate and the doped BiSbE layer, the seed layer comprising an amorphous adjustment layer and a texturing layer.

6. 10. The SOT device of claim 1, further comprising an interlayer disposed over the doped BiSbE layer, the interlayer comprising a migration barrier layer and a texturing layer.

7. 10. The SOT device of claim 1, further comprising a spin torque layer (STL) disposed over the doped BiSbE layer.

8. 1. A spin-orbit torque (SOT) device comprising: A substrate; a doped bismuth antimonide (BiSbE) layer disposed over the substrate, the doped BiSbE layer having a (012) orientation, E being a dopant, the dopant being present in an amount between about 0.5 atomic percent and about 5 atomic percent of the doped BiSbE layer, the dopant being N ２ , H ２ , C ｘ H ｙ wherein x and y are numbers, and combinations thereof; The doped BiSbE layer has a surface roughness of about 0.7 nm to about 4 nm.

9. The SOT device of claim 8 , wherein the SOT device is a write head.

10. The SOT device of claim 8 , wherein the SOT device is a read head.

11. The SOT device of claim 8 , wherein the SOT device is a magnetoresistive random access memory (MRAM) device.

12. 10. The SOT device of claim 8, further comprising a seed layer disposed between the substrate and the doped BiSbE layer, the seed layer comprising an amorphous adjustment layer and a texturing layer.

13. 10. The SOT device of claim 8, further comprising an interlayer disposed over the doped BiSbE layer, the interlayer comprising a migration barrier layer and a texturing layer.

14. 10. The SOT device of claim 8, further comprising a spin torque layer (STL) disposed over the doped BiSbE layer.

15. 1. A spin-orbit torque (SOT) device comprising: A substrate; a doped bismuth antimonide (BiSbE) layer disposed over the substrate, the doped BiSbE layer having a (012) orientation, E being a dopant, the dopant being present in an amount between about 0.5 atomic percent and about 5 atomic percent of the doped BiSbE layer; a seed layer disposed between the substrate and the doped BiSbE layer, the seed layer comprising an amorphous adjustment layer and a texturing layer; the dopant is selected from the group consisting of N2, H2, CxHy, where x and y are numbers, and combinations thereof; The doped BiSbE layer has a surface roughness of about 0.7 nm to about 4 nm.

16. The SOT device of claim 15 , wherein the SOT device is a write head.

17. The SOT device of claim 15 , wherein the SOT device is a read head.

18. The SOT device of claim 15 , wherein the SOT device is a magnetoresistive random access memory (MRAM) device.

19. an interlayer disposed on the doped BiSbE layer, the interlayer comprising a migration barrier layer and a texturing layer; 16. The SOT device of claim 15, further comprising: a spin torque layer (STL) disposed over the doped BiSbE layer.

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