Magnetic memory device and method for manufacturing a magnetic memory device

Abstract

A magnetic memory device includes a pinned layer; a free layer; a tunnel barrier layer between the pinned layer and the free layer; a first oxide layer spaced apart from the tunnel barrier layer, wherein the free layer is between the first oxide layer and the tunnel barrier layer; and a second oxide layer spaced apart from the free layer, wherein the first oxide layer is between the second oxide layer and the free layer. The first oxide layer includes an oxide of a first material, and a thickness of the first oxide layer can be in a range from 0.5 A to 2 A. The second oxide layer can include an oxide of a second material, and a thickness of the second oxide layer can be in a range from 0.5 A to 2 A. A first oxygen affinity of the first material can be greater than a second oxygen affinity of the second material.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2020-0086510, filed on July 14, 2020, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a magnetic storage device and / or a method for manufacturing the magnetic storage device. More specifically, this disclosure relates to a magnetic storage device including an oxide layer for inducing interfacial perpendicular magnetic anisotropy (i-PMA) in a free layer and / or a method for manufacturing the magnetic storage device. Background Technology

[0004] As electronic devices become faster and more power-efficient, the memory devices built into them may also require fast read / write operations and low operating voltages. Magnetic storage devices are being investigated as a potential solution to this need. Magnetic storage devices are attracting attention as a next-generation memory because they are non-volatile and capable of high-speed operation.

[0005] Meanwhile, as magnetic storage devices become increasingly integrated, STT-MRAM, which utilizes the spin-transfer torque (STT) phenomenon to store information, is under investigation. STT-MRAM stores information by inducing magnetization reversal through the direct application of current to the magnetic tunnel junction element. Highly integrated STT-MRAM may require high-speed and low-current operation. Summary of the Invention

[0006] Various aspects of this disclosure provide a magnetic storage device with improved product reliability, performance, and / or distribution.

[0007] Various aspects of this disclosure also provide a method for manufacturing magnetic storage devices with improved product reliability, performance, and / or distribution.

[0008] However, the aspects of this disclosure are not limited to those set forth herein. The foregoing and other aspects of this disclosure will become more apparent to those skilled in the art upon reference to the detailed description given below.

[0009] According to one embodiment, the magnetic storage device may include: a pinned layer; a free layer; a tunnel barrier layer between the pinned layer and the free layer; a first oxide layer spaced apart from the tunnel barrier layer, wherein the free layer is between the first oxide layer and the tunnel barrier layer; and a second oxide layer spaced apart from the free layer, wherein the first oxide layer is between the second oxide layer and the free layer. The first oxide layer may include an oxide of a first material, and the thickness of the first oxide layer may be [missing information]. to The second oxide layer may include an oxide of the second material, and the thickness of the second oxide layer may be [missing information]. to The first material can have a first oxygen affinity. The second material can have a second oxygen affinity. The second oxygen affinity can be less than the first oxygen affinity.

[0010] According to one embodiment, the magnetic storage device may include: a pinned layer; a free layer; a tunnel barrier layer between the pinned layer and the free layer; a first oxide layer spaced apart from the tunnel barrier layer, wherein the free layer is between the first oxide layer and the tunnel barrier layer; and a second oxide layer spaced apart from the free layer, wherein the first oxide layer is between the second oxide layer and the free layer. The first oxide layer may include a first material, which includes at least one of the following: calcium (Ca), strontium (Sr), magnesium (Mg), hafnium (Hf), zirconium (Zr), and aluminum (Al). The second oxide layer may include a second material different from the first material. The first material may have a first oxygen affinity. The second material may have a second oxygen affinity, which may be less than the first oxygen affinity.

[0011] According to one embodiment, the magnetic storage device may include: a pinned layer; a free layer; a tunnel barrier layer between the pinned layer and the free layer; a first oxide layer spaced apart from the tunnel barrier layer, wherein the free layer is between the first oxide layer and the tunnel barrier layer; and a second oxide layer spaced apart from the free layer, wherein the first oxide layer is between the second oxide layer and the free layer. The first oxide layer may include a first metal oxide having a first oxide decomposition potential. The second oxide layer may include a second metal oxide different from the first metal oxide. The second metal oxide may have a second oxide decomposition potential smaller than the first oxide decomposition potential.

[0012] According to one embodiment, a method for manufacturing a magnetic storage device may include: forming a pinned layer on a substrate; forming a tunnel barrier layer on the pinned layer; forming a free layer on the tunnel barrier layer; forming a first oxide layer on the free layer, the first oxide layer comprising an oxide of a first material having a first oxygen affinity; and forming a second oxide layer on the first oxide layer, the second oxide layer comprising an oxide of a second material having a second oxygen affinity less than the first oxygen affinity. Attached Figure Description

[0013] The above and other aspects and features of this disclosure will become clearer from the detailed description of exemplary embodiments with reference to the accompanying drawings, in which:

[0014] Figure 1 This is an example block diagram of a magnetic storage device according to some embodiments.

[0015] Figure 2 This is an example circuit diagram of a cell array of magnetic storage devices according to some embodiments.

[0016] Figure 3 and Figure 4 This is a schematic cross-sectional view showing a magnetic tunnel junction element of a magnetic storage device according to some embodiments.

[0017] Figures 5 to 8 Various schematic cross-sectional views of magnetic tunnel junction elements of magnetic storage devices according to some embodiments are shown.

[0018] Figure 9 This is a schematic cross-sectional view of a magnetic storage device according to some embodiments.

[0019] Figures 10 to 14 This is a diagram illustrating intermediate steps of a method for manufacturing a magnetic storage device according to some embodiments. Detailed Implementation

[0020] Expressions such as “at least one of…” modify the entire list of elements (e.g., A, B, and C) when they follow the list of elements, rather than individual elements in the list. For example, “at least one of A, B, and C,” “at least one of A, B, or C,” “one of A, B, and C, or a combination thereof,” and “one of A, B, and C, or a combination thereof” can be interpreted as covering any one of the following combinations: A; B; A and B; A and C; B and C; and A, B, and C.

[0021] When the terms “about” or “substantially” are used in conjunction with numerical values ​​in this specification, the associated numerical values ​​are intended to include manufacturing or operational tolerances (e.g., ±10%) near the stated value. Furthermore, when the words “generally” and “substantially” are used in conjunction with geometry, it is intended that precision of the geometry is not required, but the boundaries of the shape are within the scope of this disclosure. Moreover, regardless of whether a numerical value or shape is modified to “about” or “substantially”, it should be understood that these numerical values ​​and shapes should be interpreted to include manufacturing or operational tolerances (e.g., ±10%) near the stated value or shape.

[0022] In the following text, reference will be made to Figures 1 to 9 This disclosure describes magnetic tunnel junction elements and magnetic storage devices according to some embodiments of the present disclosure.

[0023] Figure 1 This is an example block diagram of a magnetic storage device according to some embodiments.

[0024] Reference Figure 1According to some embodiments, the magnetic storage device includes a cell array 1, a row decoder 2, a column decoder 3, a read / write circuit 4, and a control logic device 5.

[0025] Cell array 1 may include multiple word lines and multiple bit lines. Memory cells may be connected to the points where word lines and bit lines intersect. See later. Figure 2 The cell array 1 is described in more detail.

[0026] Line decoder 2 can be connected to cell array 1 via word lines. Line decoder 2 can select one of multiple word lines by decoding the address of an external input.

[0027] Column decoder 3 can be connected to cell array 1 via bit lines. Column decoder 3 can select one of multiple bit lines by decoding the address of an external input. The bit line selected by column decoder 3 can be connected to read / write circuitry 4.

[0028] The read / write circuit 4 can provide bit line bias under the control of the control logic device 5 for accessing selected memory cells. For example, the read / write circuit 4 can provide bit line bias to selected bit lines to write input data to or read input data from memory cells.

[0029] In some embodiments, the control logic device 5, row decoder 2, and column decoder 3 may include: processing circuitry such as hardware including logic circuitry; a hardware / software combination such as a processor executing software; or a combination thereof. For example, the processing circuitry may more specifically include, but is not limited to, a central processing unit (CPU), an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field-programmable gate array (FPGA), a system-on-a-chip (SoC), a programmable logic unit, a microprocessor, an application-specific integrated circuit (ASIC), etc.

[0030] Control logic device 5 can output control signals for controlling the magnetic storage device based on command signals provided from an external source. The control signals output from control logic device 5 can control read / write circuit 4. Control logic device 5 can operate in response to control / command signals, commands, or instructions input to it from an external source (e.g., a host (not shown)) and can be configured to access cell array 1 and control the operation of the magnetic storage device discussed herein, thereby turning control logic device 5 into a dedicated controller.

[0031] Figure 2 This is an example circuit diagram of a cell array of magnetic storage devices according to some embodiments. Figure 3 and Figure 4 This is a schematic cross-sectional view showing a magnetic tunnel junction element of a magnetic storage device according to some embodiments. For reference, Figure 3 and Figure 4 This is an example of a magnetic storage device that constitutes a spin-transfer torque magnetic random access memory (STT-MRAM).

[0032] Reference Figure 2 Cell array 1 includes multiple bit lines BL, multiple word lines WL, and multiple unit memory cells MC.

[0033] The word line WL extends in the first direction. The bit line BL may extend in a second direction that intersects the first direction to intersect the word line WL.

[0034] Unit memory cells (MCs) can be arranged in two or three dimensions. Each MC can be connected to the intersection of word lines (WLs) and bit lines (BLs) that intersect each other. Therefore, each MC connected to the word line (WL) can be connected to the read / write circuitry (e.g., via the bit line (BL)). Figure 1 (Read / write circuitry 40 in the cell). Each of the cell storage units MC may include a magnetic tunnel junction element ME and a selection element SE.

[0035] A magnetic tunnel junction element ME can be connected between a bit line BL and a select element SE, and the select element SE can be connected between the magnetic tunnel junction element ME and a word line WL. The magnetic tunnel junction element ME may include pinning layers (e.g., Figure 3 210 in the middle), free layer (e.g., Figure 3 230 in the middle) and tunnel barrier layer (e.g., Figure 3 (220 in the middle).

[0036] The selector element SE can be configured to selectively control the flow of charge through the magnetic tunnel junction element ME. For example, the selector element SF may include at least one of the following: a diode, a PNP bipolar transistor, an NPN bipolar transistor, an NMOS field-effect transistor, or a PMOS field-effect transistor. When a bipolar transistor (which is a 3-terminal element) or a MOS field-effect transistor is used to construct the selector element SE, additional wires (e.g., source lines) may be connected to the selector element SE.

[0037] Reference Figure 3 and Figure 4 According to some embodiments, the magnetic tunnel junction element of the magnetic storage device includes a pinned layer 210, a free layer 230, a tunnel barrier layer 220, a first oxide layer 240, and a second oxide layer 250.

[0038] Pinning layer 210 can have a pinned magnetization direction. For example, the magnetization direction of pinning layer 210 can be pinned regardless of the programming current flowing through it.

[0039] The pinning layer 210 may include a ferromagnetic material. For example, the pinning layer 210 may include at least one of the following: an amorphous rare earth element alloy, a multilayer thin film of alternating stacks of ferromagnetic metals (FM) and nonmagnetic metals (NM), an alloy having an L10 type crystal structure, a cobalt-based alloy, or a combination thereof, but is not limited thereto.

[0040] Amorphous rare earth element alloys can include, for example, alloys such as TbFe, TbCo, TbFeCo, DyTbFeCo, and GdTbCo. Multilayer films consisting of alternating stacks of ferromagnetic metals (FM) and nonmagnetic metals (NM) can include, for example, multilayer films such as Co / Pt, Co / Pd, CoCr / Pt, Co / Ru, Co / Os, Co / Au, and Ni / Cu. Alloys having an L10-type crystal structure can include, for example, Fe... 50 Pt 50 Fe 50 Pd 50 Co 50 Pt 50 Fe 30 Ni 20 Pt 50 and Co 30 Ni 20 Pt 50 Cobalt-based alloys may include, for example, alloys such as CoCr, CoPt, CoCrPt, CoCrTa, CoCrPtTa, CoCrNb, and CoFeB. For example, an example of pinning layer 210 comprising CoFeB will be described below.

[0041] In some embodiments, the pinning layer 210 may have perpendicular magnetic anisotropy (PMA). That is, the pinning layer 210 may have an easy magnetization axis in a direction perpendicular to the extension direction of the pinning layer 210. Figure 3 The unidirectional arrow A in the diagram indicates that the magnetization direction of the pinning layer 210 is pinned vertically.

[0042] The free layer 230 may have a variable magnetization direction. For example, the magnetization direction of the free layer 230 may vary depending on the programming current flowing through it. In some embodiments, the magnetization direction of the free layer 230 may be changed by spin-transfer torque (STT).

[0043] The free layer 230 may include at least one magnetic element. Regarding the magnetic element, the free layer 230 may include, for example, at least one of iron (Fe), nickel (Ni), or cobalt (Co), but is not limited thereto.

[0044] In some embodiments, the free layer 230 may have perpendicular magnetic anisotropy (PMA). That is, the free layer 230 may have an easy magnetization axis in a direction perpendicular to the extension direction of the free layer 230. Figure 3 The double-headed arrow B indicates that the magnetization direction of the free layer 230 can be parallel to the magnetization direction of the pinned layer 210 or can be antiparallel to the magnetization direction of the pinned layer 210.

[0045] In some embodiments, the free layer 230 may include a magnetic element capable of inducing interfacial vertical magnetic anisotropy (i-PMA) by binding with oxygen. The magnetic element may be, for example, iron (Fe). For instance, the free layer 230 is described below as including CoFe or CoFeB.

[0046] In some embodiments, the free layer 230 may have a crystal structure. For example, at least a portion of the free layer 230 may have a body-centered cubic (BCC) crystal structure.

[0047] The tunnel barrier layer 220 may be located between the pinned layer 210 and the free layer 230. The tunnel barrier layer 220 may be used as an insulating tunnel barrier for generating quantum mechanical tunneling between the pinned layer 210 and the free layer 230.

[0048] The tunnel barrier layer 220 may include, for example, at least one of the following: magnesium oxide (MgO), aluminum oxide (Al2O3), silicon oxide (SiO2), tantalum oxide (Ta2O5), silicon nitride (SiN), aluminum nitride (AlN), or combinations thereof, but is not limited thereto. For example, the tunnel barrier layer 220 is described below as including magnesium oxide having a face-centered cubic (FCC) crystal structure or a sodium chloride (NaCl) crystal structure.

[0049] The magnetic tunnel junction element, including pinned layer 210, tunnel barrier layer 220, and free layer 230, can be used as a variable resistance element that can be switched between two resistance states by an electrical signal (e.g., a programming current) applied to it. For example, when the magnetization direction of pinned layer 210 is parallel to the magnetization direction of free layer 230, the magnetic tunnel junction element can have a low resistance value and can be stored as data "0". Conversely, when the magnetization direction of pinned layer 210 is antiparallel to the magnetization direction of free layer 230, the magnetic tunnel junction element has a high resistance value and can be stored as data "1".

[0050] In some embodiments, the pinned layer 210, the tunnel barrier layer 220, and the free layer 230 may be sequentially stacked on the substrate 100. The substrate 100 may be, for example, a silicon substrate, a gallium arsenide substrate, a silicon-germanium substrate, a ceramic substrate, a quartz substrate, or a glass substrate or a semiconductor-on-insulator (SOI) substrate for display, but is not limited thereto.

[0051] The first oxide layer 240 may be spaced apart from the tunnel barrier layer 220, wherein the free layer 230 is located between the first oxide layer 240 and the tunnel barrier layer 220. For example, the first oxide layer 240 may cover the top surface of the free layer 230. The first oxide layer 240 may be in contact with the free layer 230.

[0052] The first oxide layer 240 may include an oxide of the first material. For example, the first oxide layer 240 may be a native oxide of the first material. The first material may have a first oxygen affinity. The first material may include, for example, at least one of the following: metals (e.g., calcium (Ca), strontium (Sr), beryllium (Be), magnesium (Mg), hafnium (Hf), zirconium (Zr), barium (Ba), and aluminum (Al)), borides of metals (e.g., calcium boride (CaB), aluminum boride (AlB), and zirconium boride (ZrB)), tantalum boride (TaB), titanium boride (TiB), or tantalum carbide (TaC), but is not limited thereto.

[0053] The second oxide layer 250 may be spaced apart from the free layer 230, wherein the first oxide layer 240 is located between the second oxide layer 250 and the free layer 230. For example, the second oxide layer 250 may cover the top surface of the first oxide layer 240. In some embodiments, the second oxide layer 250 may be in contact with the first free layer 230.

[0054] The second oxide layer 250 may include an oxide of a second material. For example, the second oxide layer 250 may be a native oxide of the second material. The second material may have a second oxygen affinity. The second material may include, for example, at least one of the following: titanium (Ti), tantalum (Ta), gallium (Ga), vanadium (V), zinc (Zn), manganese (Mn), or niobium (Nb), but is not limited thereto. In some embodiments, the second material may be different from the first material.

[0055] The first oxygen affinity of the first oxide layer 240 can be greater than the second oxygen affinity of the second oxide layer 250. For example, the first oxide decomposition potential of the oxide of the first material can be greater than the second oxide decomposition potential of the oxide of the second material. The difference between the first oxide decomposition potential and the second oxide decomposition potential can be 0.1V or greater (e.g., 0.1V to 2.0V and / or 0.1V to 1.55V). Here, oxide decomposition potential refers to the absolute value of the decomposition potential measured in the electrolysis of the oxide.

[0056] Table 1 below shows the known oxide decomposition potentials of several metals at 1300 K.

[0057] [Table 1]

[0058]

[0059]

[0060] For example, the first material can be calcium (Ca), and the second material can be tantalum (Ta). That is, the first oxide layer 240 can include calcium oxide (CaO), and the second oxide layer 250 can include tantalum oxide (Ta₂O₅). Referring to Table 1 above, the oxide decomposition potential of calcium (Ca) at 1300 K (approximately 2.590 V) is greater than the oxide decomposition potential of tantalum (Ta) at 1300 K (approximately 1.529 V). Therefore, the first oxygen affinity of the first oxide layer 240 can be greater than the second oxygen affinity of the second oxide layer 250.

[0061] In some embodiments, the first material may be a first metal, and the second material may be a second metal different from the first metal. For example, the first oxide layer 240 may include a first metal oxide, and the second oxide layer 250 may include a second metal oxide different from the first metal oxide. In this case, the first oxide decomposition potential of the first metal oxide may be greater than the second oxide decomposition potential of the second metal oxide.

[0062] In some embodiments, at 1300K, the first oxide decomposition potential of the first metal oxide can be 2.1V or greater, and the second oxide decomposition potential of the second metal oxide can be 2.0V or less.

[0063] In some embodiments, the first metal oxide may include at least one of the following elements: calcium (Ca), strontium (Sr), magnesium (Mg), hafnium (Hf), zirconium (Zr), or aluminum (Al). That is, the first oxide layer 240 may include at least one of the following: calcium oxide (CaO), strontium oxide (SrO), magnesium oxide (MgO), hafnium oxide (HfO2), zirconium oxide (ZrO2), or aluminum oxide (AlO).

[0064] In some embodiments, the second metal oxide may include at least one of the following: titanium (Ti), tantalum (Ta), gallium (Ga), vanadium (V), or zinc (Zn). That is, the second oxide layer 250 may include at least one of the following: titanium oxide (TiO2, Ti2O3), tantalum oxide (Ta2O5), gallium oxide (Ga2O3), vanadium oxide (VO, V2O3, VO2, V2O5), or zinc oxide (ZnO).

[0065] The second oxide layer 250 can supply oxygen atoms to the interface between the free layer 230 and the first oxide layer 240. The oxygen atoms supplied from the second oxide layer 250 can combine with magnetic atoms (e.g., iron (Fe) atoms) in the free layer 230 to induce perpendicular magnetic anisotropy (i-PMA) at the interface. For example, as... Figure 4 As shown, the free layer 230 may include an interface layer 235 in contact with the first oxide layer 240. The interface layer 235 may be bonded to oxygen atoms supplied from the second oxide layer 250 to induce interfacial perpendicular magnetic anisotropy (i-PMA). In some embodiments, the interface layer 235 may include iron-oxygen (Fe-O) bonds.

[0066] The first oxide layer 240 can control the oxygen atoms supplied from the second oxide layer 250 to the free layer 230. Since the oxygen affinity of the first oxide layer 240 is greater than that of the second oxide layer 250, the first oxide layer 240 can limit and / or prevent excessive diffusion of oxygen atoms within the free layer 230 and / or into the tunnel barrier layer 220. Furthermore, the first oxide layer 240 and the second oxide layer 250 can be bonded to each other, allowing for the control of oxygen atoms to be uniformly supplied to the free layer 230.

[0067] In some embodiments, the thickness TH1 of the first oxide layer 240 can be... to Within the range. When the thickness TH1 of the first oxide layer 240 is less than At this time, it may be impossible to control the oxygen atoms supplied from the second oxide layer 250 to the free layer 230. Therefore, oxygen atoms may over-diffuse within the free layer 230 and / or over-diffuse into the tunnel barrier layer 220, and the characteristics of the magnetic tunnel junction element (e.g., holding force, coercivity (Hc), resistivity-area product (RA), tunneling magnetoresistance ratio (TMR ratio), etc.) may deteriorate. When the thickness TH1 of the first oxide layer 240 exceeds... At that time, there are not enough oxygen atoms provided to the free layer 230. Therefore, at the interface between the free layer 230 and the first oxide layer 240, interfacial perpendicular magnetic anisotropy (i-PMA) may not be sufficiently induced.

[0068] In some embodiments, the thickness TH2 of the second oxide layer 250 can be to When the thickness TH2 of the second oxide layer 250 is less than At that time, insufficient oxygen atoms are supplied to the free layer 230. Therefore, at the interface between the free layer 230 and the first oxide layer 240, interfacial perpendicular magnetic anisotropy (i-PMA) may not be sufficiently induced. When the thickness TH2 of the second oxide layer 250 exceeds... At this time, the switching current increases excessively. Therefore, low-current operation of the magnetic tunnel junction element may not be possible.

[0069] To improve the thermal stability of magnetic storage devices, interfacial perpendicular magnetic anisotropy (i-PMA) can be induced by supplying oxygen atoms to the interface of the free layer. However, when oxygen atoms diffuse excessively within the free layer and / or into the tunnel barrier layer, the oxygen concentration in the free layer and / or tunnel barrier layer increases, potentially degrading the characteristics of the magnetic tunnel junction device (e.g., holding force, coercivity (Hc), resistivity-area product (RA), tunneling magnetoresistance ratio (TMR ratio), etc.).

[0070] However, according to some embodiments, the magnetic tunnel junction element of the magnetic storage device can limit and / or prevent the degradation of its characteristics by controlling the oxygen atoms supplied to the interface of the free layer 230. For example, as described above, since the oxygen affinity of the first oxide layer 240 is greater than that of the second oxide layer 250, the first oxide layer 240 can limit and / or prevent excessive diffusion of oxygen atoms within the free layer 230 and / or into the tunnel barrier layer 220. Therefore, a magnetic storage device with improved product reliability and performance can be provided by limiting and / or preventing the degradation of the magnetic tunnel junction element's characteristics.

[0071] Furthermore, in the magnetic tunnel junction element of the magnetic storage device according to some embodiments, a uniform interfacial vertical magnetic anisotropy (i-PMA) can be provided at the interface (e.g., interface layer 235) between the free layer 230 and the first oxide layer 240. For example, the first oxide layer 240 and the second oxide layer 250 can be bonded to each other, allowing oxygen atoms to be controlled to be uniformly supplied to the free layer 230. Therefore, a magnetic storage device with improved distribution of interfacial vertical magnetic anisotropy can be provided.

[0072] In some embodiments, the first oxide layer 240 may further include boron (B). For example, the first oxide layer 240 may include at least one of the following: calcium boride (CaB), aluminum boride (AlB), zirconium boride (ZrB), tantalum boride (TaB), or titanium boride (TiB). In some embodiments, the boride formation energy of the first oxide layer 240 may be lower than the boride formation energy of the free layer 230.

[0073] In some embodiments, the free layer 230 may include crystalline and amorphous portions. For example, the crystalline portion of the free layer 230 may be adjacent to the tunnel barrier layer 220, and the amorphous portion of the free layer 230 may be adjacent to the first oxide layer 240. In some embodiments, the boron concentration of the amorphous portion of the free layer 230 (e.g., the interface layer 235) may be greater than the boron concentration of the crystalline portion of the free layer 230 (e.g., the center of the free layer 230).

[0074] In some embodiments, the (maximum) boron concentration of the first oxide layer 240 may be greater than the (maximum) boron concentration of the free layer 230. For example, the boron concentration at the center of the first oxide layer 240 may be greater than the boron concentration in the amorphous portion of the free layer 230 (e.g., the interface layer 235).

[0075] In some embodiments, the free layer 230 and / or the first oxide layer 240 may have a uniform boron concentration. In this case, the uniform boron concentration of the first oxide layer 240 may be greater than the uniform boron concentration of the free layer 230. In some embodiments, the free layer 230 may not contain boron.

[0076] In some embodiments, the boron concentration of the free layer 230 may be 30 at% or less, and the boron concentration of the first oxide layer 240 may be 50 at% or less. In some embodiments, the second oxide layer 250 may not contain boron (B).

[0077] According to some embodiments, the magnetic tunnel junction element of the magnetic storage device can be connected to the substrate 100 and the first wire 300.

[0078] For example, a first interlayer insulating layer 105 may be formed on a substrate 100. A pinning layer 210, a tunnel barrier layer 220, a free layer 230, a first oxide layer 240, and a second oxide layer 250 may be sequentially stacked on the first interlayer insulating layer 105. Furthermore, for example, a second interlayer insulating layer 205 may be formed on the first interlayer insulating layer 105. The second interlayer insulating layer 205 may cover the first interlayer insulating layer 105, the pinning layer 210, the tunnel barrier layer 220, the free layer 230, the first oxide layer 240, and the second oxide layer 250. A first conductor 300 may be formed on the second interlayer insulating layer 205.

[0079] The first interlayer insulation layer 105 and the second interlayer insulation layer 205 may each include an insulating material, such as silicon oxide or silicon oxynitride, but are not limited thereto.

[0080] In some embodiments, a first contact plug 190 may be formed between a magnetic tunnel junction element (e.g., pinned layer 210) and a substrate 100. The first contact plug 190 may penetrate a first interlayer insulating layer 105 to connect to the substrate 100. The first contact plug 190 may include, but is not limited to, at least one of the following: a doped semiconductor material (e.g., doped silicon), a metal (e.g., tungsten, aluminum, copper, titanium, and / or tantalum), a conductive metal nitride (e.g., titanium nitride, tantalum nitride, and / or tungsten nitride), or a metal semiconductor compound (e.g., a metal silicide).

[0081] In some embodiments, the bottom electrode BE may be formed on the first interlayer insulating layer 105. For example, the bottom electrode BE may cover the bottom surface of the pinning layer 210. The bottom electrode BE may be connected to the first contact plug 190. Thus, the magnetic tunnel junction element (e.g., the pinning layer 210) may be connected to the substrate 100 via the bottom electrode BE and / or the first contact plug 190.

[0082] The bottom electrode BE may include, for example, a conductive metal nitride or a metal. In some embodiments, the bottom electrode BE may serve as a seed layer for the pinning layer 210. For example, when the pinning layer 210 is formed of a material having an L10-type crystal structure, the bottom electrode BE may include a conductive metal nitride (e.g., titanium nitride, tantalum nitride, chromium nitride, or vanadium nitride) having a face-centered cubic crystal structure (or a sodium chloride (NaCl) crystal structure). Alternatively, for example, when the pinning layer 210 has a dense hexagonal crystal structure, the bottom electrode BE may include a conductive material (e.g., ruthenium) having a dense hexagonal crystal structure. However, this is merely an example, and the bottom electrode BE may include a conductive material (e.g., titanium or tantalum).

[0083] In some embodiments, a second contact plug 290 may be formed between a magnetic tunnel junction element (e.g., a second oxide layer 250) and a substrate 100. The second contact plug 290 may penetrate a second interlayer insulating layer 205 to connect to a first wire 300. The second contact plug 290 may include, but is not limited to, at least one of the following: a doped semiconductor material (e.g., doped silicon), a metal (e.g., tungsten, aluminum, copper, titanium, and / or tantalum), a conductive metal nitride (e.g., titanium nitride, tantalum nitride, and / or tungsten nitride), or a metal semiconductor compound (e.g., a metal silicide).

[0084] In some embodiments, a top electrode TE may be formed on the second oxide layer 250. For example, the top electrode TE may cover the top surface of the second oxide layer 250. The top electrode TE may be connected to the second contact plug 290. Thus, the magnetic tunnel junction element (e.g., the second oxide layer 250) may be connected to the first wire 300 via the top electrode TE and / or the second contact plug 290.

[0085] The top electrode TE may include, for example, a conductive metal nitride or a metal. In some embodiments, the top electrode TE may protect the second oxide layer 250. For example, the top electrode TE may include at least one of ruthenium (Ru), tantalum (Ta), or their nitrides.

[0086] Figures 5 to 8 Various schematic cross-sectional views of magnetic tunnel junction elements of magnetic storage devices according to some embodiments are shown. For the sake of simplicity, references will be briefly given or omitted. Figures 1 to 4 The description is a repetitive description.

[0087] Reference Figure 5 According to some embodiments, the magnetic storage device also includes a seed layer 215.

[0088] Seed layer 215 may be formed on substrate 100. In some embodiments, seed layer 215 may cover the bottom surface of pinning layer 210. Seed layer 215 may be spaced apart from tunnel barrier layer 220, wherein pinning layer 210 is located between seed layer 215 and tunnel barrier layer 220.

[0089] Seed layer 215 can be used as a seed layer for pinning layer 210. For example, when pinning layer 210 is formed of a material having an L10-type crystal structure, seed layer 215 may include a conductive metal nitride (e.g., titanium nitride, tantalum nitride, chromium nitride, or vanadium nitride) having a face-centered cubic crystal structure (or sodium chloride (NaCl) crystal structure). Alternatively, for example, when pinning layer 210 has a dense hexagonal crystal structure, seed layer 215 may include a conductive material (e.g., ruthenium) having a dense hexagonal crystal structure.

[0090] In some embodiments, the seed layer 215 may include at least one of the following: tantalum (Ta), ruthenium (Ru), titanium (Ti), palladium (Pd), platinum (Pt), magnesium (Mg), aluminum (Al), or their nitrides. In some embodiments, the seed layer 215 may be formed using a multilayer film of stacked different nonmagnetic metals. For example, the seed layer 215 may include a first nonmagnetic layer and a second nonmagnetic layer stacked in sequence. The first nonmagnetic layer may include tantalum (Ta), and the second nonmagnetic layer may include platinum (Pt), but is not limited thereto.

[0091] Reference Figure 6 In a magnetic storage device according to some embodiments, a free layer 230, a tunnel barrier layer 220, and a pinning layer 210 are sequentially stacked on a substrate 100.

[0092] For example, the second oxide layer 250, the first oxide layer 240, the free layer 230, the tunnel barrier layer 220 and the pinning layer 210 can be sequentially stacked on the first interlayer insulating layer 105.

[0093] In some embodiments, the second oxide layer 250 may be connected to the substrate 100 via the bottom electrode BE and / or the first contact plug 190. In some embodiments, the pinning layer 210 may be connected to the first lead wire 300 via the top electrode TE and / or the second contact plug 290.

[0094] Reference Figure 7 According to some embodiments, the magnetic storage device also includes a first capping layer 260.

[0095] A first capping layer 260 may be formed on a magnetic tunnel junction element. In some embodiments, the first capping layer 260 may cover the top surface of the magnetic tunnel junction element. For example, the first capping layer 260 may cover the top surface of the second oxide layer 250. The first capping layer 260 may be spaced apart from the first oxide layer 240, wherein the second oxide layer 250 is located between the first capping layer 260 and the first oxide layer 240.

[0096] The first capping layer 260 can serve as a protective layer for the second oxide layer 250. In some embodiments, the first capping layer 260 may comprise a metal or a metal oxide. The metal may include, for example, at least one of the following: cobalt (Co), nickel (Ni), iron (Fe), tantalum (Ta), tungsten (W), and ruthenium (Ru), but is not limited thereto. The metal oxide may include, for example, at least one of the following: magnesium oxide (MgO), magnesium aluminum oxide (MgAlO), hafnium oxide (HfO), zirconium oxide (ZrO), or aluminum oxide (AlO), but is not limited thereto.

[0097] In some embodiments, the second contact plug 290 may penetrate the second interlayer insulation layer 205 and the first capping layer 260 to connect to the second oxide layer 250.

[0098] Reference Figure 8 According to some embodiments, the magnetic storage device also includes a second cover layer 270.

[0099] A second capping layer 270 may be formed on the magnetic tunnel junction element. In some embodiments, the second capping layer 270 may cover the side and top surfaces of the magnetic tunnel junction element. For example, the second capping layer 270 may conformally extend along the pinned layer 210, the tunnel barrier layer 220, the free layer 230, the first oxide layer 240, and the second oxide layer 250. More specifically, the second capping layer 270 may cover the side surfaces of the pinned layer 210, the tunnel barrier layer 220, the free layer 230, the first oxide layer 240, the second oxide layer 250, and the side and top surfaces of the first capping layer 260.

[0100] In some embodiments, the second capping layer 270 may also extend along the first interlayer insulation layer 105. For example, the second capping layer 270 may cover the top surface of the first interlayer insulation layer 105.

[0101] The second capping layer 270 can serve as a protective layer that protects the magnetic tunnel junction element from moisture or oxidation. For example, the second capping layer 270 can limit and / or prevent the characteristics of the magnetic tunnel junction element (e.g., holding force, coercivity (Hc), resistivity-area product (RA), tunneling magnetoresistance ratio (TMR ratio), etc.) from deterioration due to moisture or oxidation. The second capping layer 270 may include, for example, silicon nitride, but is not limited thereto.

[0102] In some embodiments, the second interlayer insulation layer 205 may cover the second capping layer 270.

[0103] In some embodiments, the second contact plug 290 may penetrate the second interlayer insulation layer 205, the second capping layer 270 and the first capping layer 260 to connect to the second oxide layer 250.

[0104] Figure 9 This is a schematic cross-sectional view of a magnetic storage device according to some embodiments. For the sake of simplicity, references will be briefly given or omitted. Figures 1 to 8 The description is a repetition of the previous one. For reference, Figure 9 The magnetic storage device constituting STT-MRAM is shown.

[0105] Reference Figure 9 According to some embodiments, the magnetic storage device includes select elements 12, 13, 21, and 22, a first magnetic tunnel junction element ME1, and a second magnetic tunnel junction element ME2. Select elements 12, 13, 21, and 22 are shown as MOS field-effect transistors, but this is merely an example, and the spirit of this disclosure is not limited thereto. For example, unlike the illustrated example, diodes or bipolar transistors may constitute the select elements.

[0106] Selection elements 12, 13, 21, and 22 may be formed on substrate 100. In some embodiments, selection elements 12, 13, 21, and 22 may include a source region 13, a drain region 12, a gate electrode 22, and a gate insulating layer 21. The source region 13 and the drain region 12 may be spaced apart from each other to be formed in substrate 100. The gate electrode 22 may be formed on substrate 100 between the source region 13 and the drain region 12. For example, the gate electrode 22 may extend across the top surface of substrate 100 to serve as a word line (e.g., Figure 2 (Word line WL in the text). The gate electrode 22 can be insulated from the substrate 100 through the gate insulating layer 21. The substrate 100 may include an isolation layer 11 comprising an insulating material such as silicon oxide and adjacent to the drain region 12. Figure 9 As shown, the isolation layer 11 can define the region of the substrate 100 including the source region 12, the drain region 13, and the active region below the gate electrode 22.

[0107] A third interlayer insulating layer 20 can be formed on the substrate 100 to cover the selectable elements 12, 13, 21, and 22. A source line 32 can be formed on a portion of the third interlayer insulating layer 20 corresponding to the source region 13. For example, the source line 32 can be formed to extend in the same direction as the gate electrode 22. Figure 9The diagram shows adjacent selector elements 12, 13, 21, and 22 sharing a source line 32, but this is merely an example. For instance, source lines 32 corresponding to each selector element 12, 13, 21, and 22 could, of course, be provided.

[0108] The source contact 24 and the landing contact 23 can be formed in the third interlayer insulation layer 20. The source contact 24 can penetrate the third interlayer insulation layer 20 to electrically connect the source line 32 to the source region 13. The landing contact 23 can penetrate the third interlayer insulation layer 20 to electrically connect to the drain region 12.

[0109] The fourth interlayer insulation layer 30 may be formed on the third interlayer insulation layer 20. The third contact plug 31 may be formed in the fourth interlayer insulation layer 30. The third contact plug 31 may penetrate the fourth interlayer insulation layer 30 to be electrically connected to the landing contact portion 23.

[0110] The first magnetic tunnel junction element ME1 and the second magnetic tunnel junction element ME2 can be disposed on the fourth interlayer insulating layer 30. Each of the first magnetic tunnel junction element ME1 and the second magnetic tunnel junction element ME2 can be referenced above. Figures 1 to 8 The magnetic tunnel junction elements described correspond to each other. For example, each of the first magnetic tunnel junction element ME1 and the second magnetic tunnel junction element ME2 may include a pinning layer 210, a tunnel barrier layer 220, a free layer 230, a first oxide layer 240 and a second oxide layer 250.

[0111] The first magnetic tunnel junction element ME1 and the second magnetic tunnel junction element ME2 can be electrically connected to the drain region 12, for example, through the bottom electrode BE, the third contact plug 31 and the landing contact 23.

[0112] A fifth interlayer insulating layer 40 may be formed on the fourth interlayer insulating layer 30. A second conductor 50 may be formed on the fifth interlayer insulating layer 40. For example, the second conductor 50 may be electrically connected to the first magnetic tunnel junction element ME1 and the second magnetic tunnel junction element ME2 via the fourth contact plug 41. The second conductor 50 may extend to intersect with the gate electrode 22 to serve as a bit line (e.g., Figure 2 (BL in the middle).

[0113] Each of the third interlayer insulating layer 20, the fourth interlayer insulating layer 30, and the fifth interlayer insulating layer 40 may include an insulating material, such as silicon oxide or silicon oxynitride, but is not limited thereto. The landing contact 23, the source line contact 24, the source line 32, the third contact plug 31, the fourth contact plug 41, and the second conductor 50 may include conductive materials, such as tungsten (W), ruthenium (Ru), tantalum (Ta), copper (Cu), aluminum (Al), or doped polycrystalline silicon, but is not limited thereto.

[0114] Although not shown, a metal wire electrically connected to the peripheral circuit unit (not shown) may also be formed on the second conductor 50.

[0115] In the following text, reference will be made to Figures 1 to 14 Methods for manufacturing magnetic tunnel junction elements and magnetic storage devices according to some example embodiments of the present disclosure are described.

[0116] Figures 10 to 14 This is a diagram illustrating intermediate steps of a method for manufacturing a magnetic storage device according to some embodiments. For the sake of simplicity, references will be briefly given or omitted. Figures 1 to 9 The description is a repetitive description.

[0117] Reference Figure 10 A first interlayer insulating layer 105 and a first contact plug 190 are formed on the substrate 100.

[0118] For example, a first interlayer insulating layer 105 may be formed on the substrate 100. Subsequently, a first contact plug 190 may be formed that penetrates the first interlayer insulating layer 105 to connect with the substrate 100.

[0119] Reference Figure 11 A preliminary pinning layer 210L, a preliminary tunnel barrier layer 220L, a preliminary free layer 230L, a first preliminary oxide layer 240L, and a second preliminary oxide layer 250L are formed on a substrate 100.

[0120] In some embodiments, the initial pinning layer 210L, the initial tunnel barrier layer 220L, the initial free layer 230L, the first initial oxide layer 240L, and the second initial oxide layer 250L may be sequentially stacked on the first interlayer insulating layer 105.

[0121] The initial anchoring layer 210L, the initial tunnel barrier layer 220L, and the initial free layer 230L can respectively include the above-mentioned components. Figure 3 and Figure 4 The pinning layer 210, tunnel barrier layer 220, and free layer 230 described herein are made of the same material. For example, the initial pinning layer 210L may include CoFeB, the initial tunnel barrier layer 220L may include MgO, and the initial free layer 230L may include CoFeB.

[0122] Each of the preliminary pinning layer 210L, the preliminary tunnel barrier layer 220L, and the preliminary free layer 230L can be formed by, for example, physical vapor deposition (PVD) processes (e.g., sputtering), chemical vapor deposition (CVD) processes, or atomic layer deposition (ALD) processes, but is not limited thereto.

[0123] The first preliminary oxide layer 240L may include a first material having a first oxygen affinity. The first material may include, for example, at least one of the following: metals (e.g., calcium (Ca), strontium (Sr), beryllium (Be), magnesium (Mg), hafnium (Hf), zirconium (Zr), barium (Ba), and aluminum (Al)), borides of metals (e.g., calcium boride (CaB), aluminum boride (AlB), and zirconium boride (ZrB)), tantalum boride (TaB), titanium boride (TiB), or tantalum carbide (TaC), but is not limited thereto.

[0124] The first preliminary oxide layer 240L may include an oxide of the first material. For example, the first preliminary oxide layer 240L may be a native oxide of the first material.

[0125] The second preliminary oxide layer 250L may include a second material having a second oxygen affinity that is less than a first oxygen affinity. The second material may include, for example, at least one of the following: titanium (Ti), tantalum (Ta), gallium (Ga), vanadium (V), zinc (Zn), manganese (Mn), or niobium (Nb), but is not limited thereto. In some embodiments, the second material may be different from the first material.

[0126] The second preliminary oxide layer 250L may include an oxide of the second material. For example, the second preliminary oxide layer 250L may be a native oxide of the second material.

[0127] In some embodiments, each of the first preliminary oxide layer 240L and the second preliminary oxide layer 250L can be formed by a deposition process. For example, each of the first preliminary oxide layer 240L and the second preliminary oxide layer 250L can be formed by a PVD process, a CVD process, or an ALD process, but is not limited thereto.

[0128] In some embodiments, a bottom electrode layer BEL may also be formed on the first interlayer insulating layer 105. For example, a bottom electrode layer BEL extending along the top surface of the first interlayer insulating layer 105 and the top surface of the first contact plug 190 may be formed before the formation of the initial pinning layer 210L. The bottom electrode layer BEL may include components as described above. Figure 3 and Figure 4 The bottom electrode BE is made of the same material as described.

[0129] In some embodiments, a preliminary seed layer 215L may also be formed on the first interlayer insulating layer 105. For example, a preliminary seed layer 215L extending along the top surface of the bottom electrode layer BEL may be formed before the formation of the preliminary pinning layer 210L. The preliminary seed layer 215L may serve as a seed layer for the preliminary pinning layer 210L. The preliminary seed layer 215L may include components as described above. Figure 5The material of the seed layer 215 described in the description is the same as that described in the description.

[0130] In some embodiments, a preliminary capping layer 260L may also be formed on the second preliminary oxide layer 250L. For example, after forming the second preliminary oxide layer 250L, a preliminary capping layer 260L extending along the top surface of the second preliminary oxide layer 250L may be formed. The preliminary capping layer 260L can serve as a protective layer for protecting the second preliminary oxide layer 250L. The preliminary capping layer 260L may include components as described above. Figure 7 The material of the first capping layer 260 described in the description is the same as that described in the description.

[0131] Reference Figure 12 A pinning layer 210, a tunnel barrier layer 220, a free layer 230, a first oxide layer 240, and a second oxide layer 250 are formed on a substrate 100.

[0132] For example, it is possible to Figure 11 The preliminary pinning layer 210L, preliminary tunnel barrier layer 220L, preliminary free layer 230L, first preliminary oxide layer 240L, and second preliminary oxide layer 250L are patterned. Therefore, a magnetic tunnel junction element including the pinning layer 210, tunnel barrier layer 220, free layer 230, first oxide layer 240, and second oxide layer 250 can be formed.

[0133] In some embodiments, the bottom electrode layer BEL, the preliminary seed layer 215L, and the preliminary capping layer 260L can be patterned together with the preliminary pinning layer 210L, the preliminary tunnel barrier layer 220L, the preliminary free layer 230L, the first preliminary oxide layer 240L, and the second preliminary oxide layer 250L. Thus, the bottom electrode BF, the seed layer 215, and the first capping layer 260 can be formed.

[0134] Reference Figure 13 A second capping layer 270 and a second interlayer insulating layer 205 are formed on the substrate 100.

[0135] For example, the second capping layer 270 may cover the side surfaces of the pinned layer 210, the tunnel barrier layer 220, the free layer 230, the first oxide layer 240, the second oxide layer 250, and the side and top surfaces of the first capping layer 260. In some embodiments, the second capping layer 270 may cover the top surface of the first interlayer insulation layer 105.

[0136] The second interlayer insulation layer 205 may cover the first interlayer insulation layer 105, the pinned layer 210, the tunnel barrier layer 220, the free layer 230, the first oxide layer 240, and the second oxide layer 250. For example, the second interlayer insulation layer 205 may cover the second capping layer 270.

[0137] Reference Figure 14 The heat treatment process is then performed.

[0138] Heat treatment processes may include, for example, annealing, but are not limited to.

[0139] Through a heat treatment process, the second oxide layer 250 can supply oxygen atoms to the interface between the free layer 230 and the first oxide layer 240. The oxygen atoms supplied from the second oxide layer 250 can bond with magnetic atoms (e.g., iron (Fe) atoms) of the free layer 230 to induce interfacial perpendicular magnetic anisotropy (i-PMA). For example, the interface layer 235 can bond with oxygen atoms supplied from the second oxide layer 250 to induce interfacial perpendicular magnetic anisotropy (i-PMA). In some embodiments, the interface layer 235 may include iron-oxygen (Fe-O) bonds.

[0140] During the heat treatment process, the first oxide layer 240 can control the supply of oxygen atoms from the second oxide layer 250 to the free layer 230. Since the oxygen affinity of the first oxide layer 240 is greater than that of the second oxide layer 250, the first oxide layer 240 can limit and / or prevent excessive diffusion of oxygen atoms within the free layer 230 and / or into the tunnel barrier layer 220. Furthermore, the first oxide layer 240 and the second oxide layer 250 can be bonded to each other, allowing for the control of the uniform supply of oxygen atoms to the free layer 230.

[0141] Therefore, a method for manufacturing magnetic storage devices with improved product reliability, performance, and distribution can be provided.

[0142] Although some exemplary embodiments have been described, the embodiments presented in this disclosure are used in a general and descriptive sense only and are not intended to be limiting. Those skilled in the art will understand that many variations and modifications can be made to the embodiments of the inventive concept without substantially departing from the principles of the inventive concept as defined in this disclosure by the appended claims.

Claims

1. A magnetic storage device, comprising: Stapling layer; Free layer; A tunnel barrier layer, located between the pinned layer and the free layer; A first oxide layer is spaced apart from the tunnel barrier layer, wherein the free layer is located between the first oxide layer and the tunnel barrier layer, the first oxide layer comprising an oxide of a first material having a first oxygen affinity, and the thickness of the first oxide layer being in the range of 0.3 Å to 2.0 Å. as well as A second oxide layer is spaced apart from the free layer, wherein the first oxide layer is located between the second oxide layer and the free layer, the second oxide layer comprising an oxide of a second material having a lower oxygen affinity than the first oxygen affinity, and the thickness of the second oxide layer being in the range of 0.1 Å to 5.0 Å. The free layer and the first oxide layer contain boron (B), and the boron concentration in the free layer is less than the boron concentration in the first oxide layer.

2. The magnetic storage device according to claim 1, wherein, The first oxide decomposition potential of the oxide of the first material is greater than the second oxide decomposition potential of the oxide of the second material.

3. The magnetic storage device according to claim 1, wherein, The free layer includes magnetic elements configured to merge with oxygen bonds to induce interfacial vertical magnetic anisotropy (i-PMA).

4. The magnetic storage device according to claim 1, further comprising: Substrate, wherein, The pinned layer, the free layer, the tunnel barrier layer, the first oxide layer, and the second oxide layer are sequentially stacked on the substrate.

5. The magnetic storage device according to claim 4, further comprising: Seed layer, located below the bottom surface of the pinning layer; as well as A first capping layer covers the top surface of the second oxide layer.

6. The magnetic storage device according to claim 5, further comprising: The second capping layer covers the side surfaces of the seed layer, the pinning layer, the free layer, the tunnel barrier layer, the first oxide layer, the second oxide layer, and the side and top surfaces of the first capping layer.

7. The magnetic storage device according to claim 6, wherein, The second capping layer comprises silicon nitride.

8. The magnetic storage device according to claim 1, wherein, The first oxide layer is a natural oxide of the first material, and The second oxide layer is a natural oxide of the second material.

9. The magnetic storage device according to claim 1, wherein, The second oxide layer does not contain boron (B).

10. The magnetic storage device according to claim 1, wherein, The boron concentration of the free layer is 30 at% or less, and The boron concentration of the first oxide layer is 50 at% or less.

11. A magnetic storage device, comprising: Stapling layer; Free layer; A tunnel barrier layer, located between the pinned layer and the free layer; A first oxide layer is spaced apart from the tunnel barrier layer, wherein the free layer is between the first oxide layer and the tunnel barrier layer, and the first oxide layer comprises a first material, the first material comprising at least one of the following: calcium (Ca), strontium (Sr), magnesium (Mg), hafnium (Hf), zirconium (Zr), and aluminum (Al), the first material having a first oxygen affinity; as well as A second oxide layer is spaced apart from the free layer, wherein the first oxide layer is located between the second oxide layer and the free layer. The second oxide layer comprises a second material different from the first material, the second material having a lower oxygen affinity than the first oxygen affinity. The free layer and the first oxide layer contain boron (B), and the boron concentration in the free layer is less than the boron concentration in the first oxide layer.

12. The magnetic storage device according to claim 11, wherein, The second material includes at least one of the following: titanium (Ti), tantalum (Ta), gallium (Ga), vanadium (V), and zinc (Zn).

13. The magnetic storage device according to claim 11, wherein, The thickness of the first oxide layer is in the range of 0.3 Å to 2.0 Å, and The thickness of the second oxide layer is in the range of 0.1 Å to 5.0 Å.

14. The magnetic storage device according to claim 11, wherein, The free layer includes an interface layer in contact with the first oxide layer, and The interface layer is configured to induce interfacial vertical magnetic anisotropy (i-PMA).

15. A magnetic storage device, comprising: Stapling layer; Free layer; A tunnel barrier layer, located between the pinned layer and the free layer; A first oxide layer is spaced apart from the tunnel barrier layer, wherein the free layer is between the first oxide layer and the tunnel barrier layer, and the first oxide layer comprises a first metal oxide having a first oxide decomposition potential. as well as A second oxide layer is spaced apart from the free layer, wherein the first oxide layer is located between the second oxide layer and the free layer. The second oxide layer comprises a second metal oxide different from the first metal oxide, and the decomposition potential of the second metal oxide is lower than that of the first oxide. The free layer and the first oxide layer contain boron (B), and the boron concentration in the free layer is less than the boron concentration in the first oxide layer.

16. The magnetic storage device according to claim 15, wherein, The difference between the decomposition potential of the first oxide and the decomposition potential of the second oxide is 0.1 V or greater.

17. The magnetic storage device according to claim 15, wherein, At 1300 K, the decomposition potential of the first oxide is 2.1 V or greater, and The decomposition potential of the second oxide at 1300K is 2.0 V or less.

18. The magnetic storage device according to claim 15, wherein, The thickness of the first oxide layer is in the range of 0.3 Å to 2.0 Å, and The thickness of the second oxide layer is in the range of 0.1 Å to 5.0 Å.

19. The magnetic storage device according to claim 15, wherein, The free layer comprises iron (Fe), The first metal oxide comprises at least one of the following: calcium (Ca), strontium (Sr), magnesium (Mg), hafnium (Hf), zirconium (Zr), and aluminum (Al), and The second metal oxide includes at least one of the following: titanium (Ti), tantalum (Ta), gallium (Ga), vanadium (V), and zinc (Zn).

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