Magnetic storage device
By placing hafnium boron compounds above the storage layer of the magnetic storage device or introducing silicon and molybdenum in the buffer layer, the problem of high defective rate caused by miniaturization and narrow spacing of storage cells is solved, and the reliability and performance of the storage cells are improved.
Patent Information
- Application Number
- CN202411261263.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-03-14
- Filing Date
- 2024-09-10
- Publication Date
- 2025-09-16
AI Technical Summary
In the process of miniaturization and narrowing the pitch of storage cells in existing magnetic storage devices, the defective rate of storage cells is high, which affects the storage capacity and performance.
A metal capping layer containing hafnium boron (HfB) or hafnium (Hf) is provided above the memory layer, or silicon (Si) is introduced into the buffer layer and molybdenum (Mo) is used in the non-magnetic layer to improve the reliability and performance of the memory cell.
The defective generation rate of the storage unit is reduced, and the performance and storage capacity of the storage unit are improved.
Smart Images
Figure CN120659523A_ABST
Abstract
Description
Technical Field
[0001] The present embodiments generally relate to magnetic storage devices. Background Art
[0002] A magnetic storage device (MRAM: Magnetoresistive Random Access Memory) using a magnetoresistive effect element as a storage element is known. Summary of the Invention
[0003] Generally speaking, according to one embodiment, a magnetic storage device includes:
[0004] A magnetic storage device of an embodiment comprises: a first non-magnetic layer comprising silicon (Si); a first ferromagnetic (ferromagnetic) layer disposed above the first non-magnetic layer; a second non-magnetic layer disposed above the first ferromagnetic layer; a second ferromagnetic layer disposed above the second non-magnetic layer; a third non-magnetic layer disposed above the second ferromagnetic layer; a third ferromagnetic layer disposed above the third non-magnetic layer; a fourth non-magnetic layer disposed above the third ferromagnetic layer and comprising magnesium (Mg) and oxygen; a fifth non-magnetic layer disposed above the fourth non-magnetic layer and comprising molybdenum (Mo); a sixth non-magnetic layer disposed above the fifth non-magnetic layer and comprising hafnium (Hf); and a seventh non-magnetic layer disposed above the sixth non-magnetic layer and comprising ruthenium (Ru). BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Figure 1 This is a block diagram showing the configuration of a storage system including the magnetic storage device according to the first embodiment.
[0006] Figure 2 This is a circuit diagram of a memory cell array of the magnetic memory device according to the first embodiment.
[0007] Figure 3 It is a perspective view showing the structure of a memory cell array of the magnetic storage device according to the first embodiment.
[0008] Figure 4 It is a cross-sectional view of the variable resistance element of the magnetic memory device according to the first embodiment.
[0009] Figure 5 It is a figure which shows the cross-sectional structure and characteristics of the metal coating layer in 1st Embodiment and Comparative Example 1.
[0010] Figure 6 It is a cross-sectional view of a variable resistance element of the magnetic memory device according to the second embodiment.
[0011] Figure 7It is a diagram showing the cross-sectional structure of the metal coating layer and the buffer layer in the second embodiment and comparative example 2-4.
[0012] Figure 8 Graphs showing the relationship between the exchange coupling magnetic field and the magnetoresistance change rate in the second embodiment and comparative example 2-4.
[0013] Figure 9 It is a cross-sectional view of a variable resistance element of a magnetic memory device according to a third embodiment.
[0014] Figure 10 It is a diagram showing the cross-sectional structures and characteristics of the metal covering layer and the oxide covering layer in the third embodiment and comparative examples 5-7.
[0015] Figure 11 It is a cross-sectional view of a variable resistance element included in a memory cell of a magnetic memory device according to a fourth embodiment.
[0016] Figure 12 It is a cross-sectional view of a variable resistance element included in a memory cell of a magnetic memory device according to a fifth embodiment.
[0017] Figure 13 It is a cross-sectional view of a variable resistance element included in a memory cell of a magnetic memory device according to a sixth embodiment. DETAILED DESCRIPTION
[0018] The following embodiments are described with reference to the accompanying drawings. In the following description, components having the same function and configuration are denoted by common reference numerals. The embodiments described below illustrate devices and methods for embodying the technical concepts of the embodiments, and do not specify the materials, shapes, structures, and arrangements of the components as described below.
[0019] 1. First Implementation
[0020] First, a storage system including the magnetic storage device according to the first embodiment will be described.
[0021] 1.1 Storage System
[0022] Reference Figure 1 An example of a storage system will be described. Figure 1 1 is a block diagram showing the configuration of a storage system MS including the magnetic storage device according to the first embodiment.
[0023] like Figure 1 As shown, the storage system MS includes a magnetic storage device 1 and a storage controller 2. The magnetic storage device 1 operates under the control of the storage controller 2. The storage controller 2 can respond to requests (or commands) from an external host device and instruct the magnetic storage device 1 to perform read operations and write operations.
[0024] Magnetic storage device 1 is a type of resistance change memory. It is a storage device that uses an MTJ (Magnetic Tunnel Junction) element as a memory cell. An MTJ element utilizes the magnetoresistance effect of a magnetic tunnel junction. An MTJ element is also called a magnetoresistance element.
[0025] The magnetic storage device 1 includes, for example, a memory cell array 11 , an input / output circuit 12 , a control circuit 13 , a row selection circuit 14 , a column selection circuit 15 , a write circuit 16 , and a read circuit 17 .
[0026] The memory cell array 11 includes a plurality of memory cells MC, a plurality of word lines WL, and a plurality of bit lines BL. Figure 1 Figure 1 shows a set of memory cells MC, word lines WL, and bit lines BL. Memory cells MC can store data in a nonvolatile manner. Memory cells MC are connected between a word line WL and a bit line BL, corresponding to a row and column pair. A row address is assigned to the word line WL. A column address is assigned to the bit line BL. One or more memory cells MC can be identified by selecting a row and one or more columns.
[0027] The input / output circuit 12 is connected to the storage controller 2 and manages communication between the magnetic storage device 1 and the storage controller 2. The input / output circuit 12 transfers the control signal CNT and command CMD received from the storage controller 2 to the control circuit 13. The input / output circuit 12 also transfers the row address and column address included in the address signal ADD received from the storage controller 2 to the row selection circuit 14 and the column selection circuit 15, respectively. The input / output circuit 12 transfers the data DAT (write data) received from the storage controller 2 to the write circuit 16. The input / output circuit 12 transfers the data DAT (read data) received from the read circuit 17 to the storage controller 2.
[0028] The control circuit 13 controls the overall operation of the magnetic storage device 1. For example, the control circuit 13 executes read operations, write operations, and the like based on the control signal CNT and the command CMD. For example, during a write operation, the control circuit 13 supplies a voltage used to write data to the write circuit 16. Furthermore, during a read operation, the control circuit 13 supplies a voltage used to read data to the read circuit 17.
[0029] The row selection circuit 14 is connected to a plurality of word lines WL. The row selection circuit 14 selects one word line WL specified by a row address. The selected word line WL is electrically connected to, for example, a driver circuit (not shown).
[0030] The column selection circuit 15 is connected to a plurality of bit lines BL. The column selection circuit 15 selects one or more bit lines BL specified by a column address. The selected bit line BL is electrically connected to, for example, a driver circuit (not shown).
[0031] The write circuit 16 supplies a voltage for writing data to the column select circuit 15 based on the control of the control circuit 13 and the data DAT (write data) received from the input / output circuit 12. When a current based on the write data flows through the memory cell MC, the desired data is written into the memory cell MC.
[0032] Read circuit 17 includes a sense amplifier. Under control of control circuit 13, read circuit 17 supplies a voltage used for data reading to column select circuit 15. The sense amplifier then determines the data stored in memory cell MC based on the voltage or current of the selected bit line BL. Read circuit 17 then transfers data DAT (read data) corresponding to the determination result to input / output circuit 12.
[0033] 1.2 Magnetic Storage Devices
[0034] 1.2.1 Circuit Structure of Memory Cell Array
[0035] Reference Figure 2 An example of a circuit configuration of the memory cell array 11 included in the magnetic storage device 1 will be described. Figure 2 1 is a circuit diagram showing a circuit configuration of a memory cell array 11 included in the magnetic storage device 1 according to the first embodiment. Figure 2 WL0 and WL1 among a plurality of word lines WL, and BL0 and BL1 among a plurality of bit lines BL are extracted and shown.
[0036] like Figure 2 As shown, one memory cell MC is connected between WL0 and BL0, between WL0 and BL1, between WL1 and BL0, and between WL1 and BL1. A plurality of memory cells MC are arranged in a matrix within the memory cell array 11, for example.
[0037] Each memory cell MC includes a variable resistor element VR and a switch element SE. The variable resistor element VR and the switch element SE are connected in series between the associated bit line BL and word line WL. For example, one end of the variable resistor element VR is connected to the bit line BL. The other end of the variable resistor element VR is connected to one end of the switch element SE. The other end of the switch element SE is connected to the word line WL. Furthermore, the connection relationship between the variable resistor element VR and the switch element SE between the bit line BL and the word line WL can be reversed. That is, one end of the variable resistor element VR is connected to the word line WL, and the other end of the variable resistor element VR is connected to one end of the switch element SE. The other end of the switch element SE can also be connected to the bit line BL.
[0038] The variable resistor element VR corresponds to the MTJ element. The variable resistor element VR can store data non-volatilely based on its resistance value. For example, a memory cell MC including the variable resistor element VR in a high resistance state stores data "1." A memory cell MC including the variable resistor element VR in a low resistance state stores data "0." The data associated with the resistance value of the variable resistor element VR can also be assigned in other settings. The resistance state of the variable resistor element VR can change according to the current flowing through the variable resistor element VR.
[0039] The switching element SE is, for example, a bidirectional diode. The switching element SE functions as a selector that controls the supply of current to the associated variable resistance element VR. Specifically, the switching element SE included in a memory cell MC is turned off when the voltage applied to the memory cell MC is lower than the threshold voltage of the switching element SE, and is turned on when the voltage applied to the memory cell MC is greater than the threshold voltage of the switching element SE. The switching element SE in the off state functions as an insulator with a high resistance value. When the switching element SE is in the off state, the flow of current between the word line WL and the bit line BL connected to the memory cell MC is suppressed. When the switching element SE is in the on state, the switching element SE functions as a conductor with a low resistance value. When the switching element SE is in the on state, current flows between the word line WL and the bit line BL connected to the memory cell MC. In other words, the switching element SE can switch whether or not current flows, regardless of the direction of current flow, depending on the magnitude of the voltage applied to the memory cell MC. Alternatively, other elements such as transistors may be used as the switching element SE.
[0040] 1.2.2 Structure of Memory Cell Array
[0041] Below, an example of the structure of the memory cell array 11 possessed by the magnetic storage device 1 is described. In the following description, an XYZ orthogonal coordinate system is used. The X direction corresponds to the extension direction of the bit line BL. The Y direction corresponds to the extension direction of the word line WL. The Z direction corresponds to the direction perpendicular to the surface of the semiconductor substrate used to form the magnetic storage device 1. The term "lower" and its derivatives and related terms indicate the position of a smaller coordinate on the Z axis. The term "upper" and its derivatives and related terms indicate the position of a larger coordinate on the Z axis. In the stereogram, section lines are appropriately added. The section lines added to the stereogram are not necessarily related to the raw materials and characteristics of the components to which the section lines are added. In the stereogram and the cross-sectional view, the illustration of the structure such as the interlayer insulating film is omitted.
[0042] Reference Figure 3 An example of a three-dimensional structure of the memory cell array 11 included in the magnetic storage device 1 will be described. Figure 3 It is a perspective view showing the structure of a memory cell array 11 included in the magnetic storage device 1 according to the first embodiment.
[0043] like Figure 3 As shown, the memory cell array 11 includes a plurality of conductive layers 20 , a plurality of conductive layers 21 , and a plurality of memory cells MC.
[0044] Each of the plurality of conductive layers 20 has a portion extending in the X direction. The plurality of conductive layers 20 are arranged in the Y direction and are separated from each other. Each conductive layer 20 serves as a bit line BL.
[0045] Each of the plurality of conductive layers 21 has a portion extending in the Y direction. The plurality of conductive layers 21 are arranged in the X direction and are separated from each other. Each conductive layer 21 serves as a word line WL.
[0046] A wiring layer comprising multiple conductive layers 21 is provided above a wiring layer comprising multiple conductive layers 20. A memory cell MC is provided at each intersection of the multiple conductive layers 20 and 21. In other words, each memory cell MC is provided between the associated bit line BL and word line WL. Each memory cell MC has a columnar structure. In this example, a variable resistance element VR is provided above the conductive layer 20. A switching element SE is provided above the variable resistance element VR. A conductive layer 21 is provided above the switching element SE.
[0047] Furthermore, although the case where the variable resistance element VR is provided below the switching element SE has been exemplified, the variable resistance element VR may also be provided above the switching element SE depending on the circuit configuration of the memory cell array 11 .
[0048] 1.2.3 Cross-sectional structure of variable resistor element
[0049] Next, refer to Figure 4 The cross-sectional structure of the variable resistance element VR included in the memory cell MC will be described. Figure 4 It is a cross-sectional view of a variable resistance element VR included in a memory cell MC of the magnetic memory device 1 according to the first embodiment.
[0050] like Figure 4 As shown, the variable resistance element VR includes, for example, a non-magnetic layer 30, a ferromagnetic (ferromagnetic) layer 31, a non-magnetic layer 32, a ferromagnetic layer 33, a non-magnetic layer 34, a ferromagnetic layer 35, a non-magnetic layer 36, and a non-magnetic layer 37. Figure 4 In the following figures, the magnetization direction of the magnetic layer is shown by arrows. The bidirectional arrows indicate that the magnetization direction is variable.
[0051] The non-magnetic layer 30, the ferromagnetic layer 31, the non-magnetic layer 32, the ferromagnetic layer 33, the non-magnetic layer 34, the ferromagnetic layer 35, the non-magnetic layer 36, and the non-magnetic layer 37 are stacked in this order from the conductive layer 20 (bit line BL) side toward the conductive layer 21 (word line WL) side (in the Z direction).
[0052] Specifically, the nonmagnetic layer 30 is provided above the conductive layer 20 (in the Z direction). The ferromagnetic layer 31 is provided above the nonmagnetic layer 30. The nonmagnetic layer 32 is provided above the ferromagnetic layer 31. The ferromagnetic layer 33 is provided above the nonmagnetic layer 32. The nonmagnetic layer 34 is provided above the ferromagnetic layer 33. The ferromagnetic layer 35 is provided above the nonmagnetic layer 34. The nonmagnetic layer 36 is provided above the ferromagnetic layer 35. The nonmagnetic layer 37 is provided above the nonmagnetic layer 36. The conductive layer 21 is provided above the nonmagnetic layer 37.
[0053] In other words, the ferromagnetic layer 33 is provided between the ferromagnetic layer 31 and the ferromagnetic layer 35. The nonmagnetic layer 34 is provided between the ferromagnetic layer 33 and the ferromagnetic layer 35. The nonmagnetic layer 32 is provided between the ferromagnetic layer 31 and the ferromagnetic layer 33. The ferromagnetic layer 31 is provided between the nonmagnetic layer 30 and the nonmagnetic layer 32. The nonmagnetic layer 30 is provided between the conductive layer 20 and the ferromagnetic layer 31. The ferromagnetic layer 35 is provided between the nonmagnetic layer 34 and the nonmagnetic layer 36. The nonmagnetic layer 36 is provided between the ferromagnetic layer 35 and the nonmagnetic layer 37. The nonmagnetic layer 37 is provided between the nonmagnetic layer 36 and the conductive layer 21.
[0054] The nonmagnetic layer 30 is a nonmagnetic conductor. The nonmagnetic layer (buffer layer BL) 30 functions as a layer for controlling the desired crystal orientation of the ferromagnetic layer 31 formed thereon. The nonmagnetic layer 30 includes a first layer 30a and a second layer 30b. The second layer 30b is provided above the first layer 30a. In other words, the second layer 30b is provided between the first layer 30a and the ferromagnetic layer 31.
[0055] The first layer 30a has an amorphous structure and contains hafnium (Hf) or hafnium boride (HfB).
[0056] The second layer 30b has a BCC (body centered cubic) crystal structure and has a
[110] plane of the BCC crystal structure in a direction perpendicular to the stacking direction
[100] of the stacking structure. By using such a second layer 30b, the ferromagnetic layer 31 can be well oriented on the FCC (face centered cubic)
[111] plane or the HCP (hexagonal close packed)
[0001] plane. As a result, the perpendicular magnetic anisotropy of the ferromagnetic layer 31 can be improved. The second layer 30b can contain at least one element selected from molybdenum (Mo), tungsten (W), and tantalum (Ta). That is, the second layer 30b can be a molybdenum (Mo) layer, a tungsten (W) layer, or a tantalum (Ta) layer. The second layer 30b can also be an alloy layer of two or more elements selected from molybdenum (Mo), tungsten (W), and tantalum (Ta).
[0057] In addition, the non-magnetic layer 30 is Figure 4 In the example shown, two layers are shown, but a laminated body in which three or more layers are laminated may also be used.
[0058] The ferromagnetic layer 31 is a ferromagnetic conductor. The ferromagnetic layer 31 has an easy magnetization axis in a direction perpendicular to the film surface. Figure 4 In the example shown, the magnetization direction of the ferromagnetic layer 31 is oriented toward the ferromagnetic layer 33. The magnitude of the magnetic field required to reverse the magnetization direction of the ferromagnetic layer 31 is, for example, greater than that of the ferromagnetic layer 33. The leakage magnetic field from the ferromagnetic layer 31 reduces the effect of the leakage magnetic field from the ferromagnetic layer 33 on the magnetization direction of the ferromagnetic layer 35. In other words, the ferromagnetic layer 31 functions as a shift canceling layer (SCL).
[0059] The ferromagnetic layer 31 may contain, for example, at least one element selected from iron (Fe), cobalt (Co), and nickel (Ni). Furthermore, the ferromagnetic layer 31 may contain, as an impurity, at least one element selected from boron (B), phosphorus (P), carbon (C), aluminum (Al), silicon (Si), tantalum (Ta), molybdenum (Mo), chromium (Cr), hafnium (Hf), tungsten (W), and titanium (Ti). Specifically, the ferromagnetic layer 31 may contain cobalt iron boron (CoFeB). The ferromagnetic layer 31 may contain at least one binary compound selected from iron boride (FeB), cobalt platinum (CoPt), cobalt nickel (CoNi), and cobalt palladium (CoPd).
[0060] The non-magnetic layer 32 is a non-magnetic conductor. It serves as a spacer layer (SP) between the ferromagnetic layer 31 and the ferromagnetic layer 33, and is antiferromagnetically coupled to the ferromagnetic layer 31. As a result, the magnetization direction of the ferromagnetic layer 31 is fixed in an antiparallel direction relative to the magnetization direction of the ferromagnetic layer 33. This coupled structure of the ferromagnetic layer 31, the non-magnetic layer 32, and the ferromagnetic layer 33 is called a SAF (Synthetic Anti-Ferromagnetic) structure. The non-magnetic layer 32, for example, contains at least one element selected from ruthenium (Ru), osmium (Os), iridium (Ir), vanadium (V), and chromium (Cr).
[0061] The ferromagnetic layer 33 is a ferromagnetic conductor. The ferromagnetic layer 33 has an easy magnetization axis in a direction perpendicular to the film surface. The magnetization direction of the ferromagnetic layer 33 is fixed to the ferromagnetic layer 31 side or the ferromagnetic layer 35 side. Figure 4 In the example shown, the magnetization direction of the ferromagnetic layer 33 is fixed to the ferromagnetic layer 31. Thus, the ferromagnetic layer 33 is used as a reference layer RL (reference layer) of the MTJ element. The reference layer RL is also called a "pinned layer" or a "fixed layer."
[0062] The ferromagnetic layer 33 includes ferromagnetic layers 33a and 33b. The ferromagnetic layer 33a is disposed above the nonmagnetic layer 32. The ferromagnetic layer 33b is disposed above the ferromagnetic layer 33a. The ferromagnetic layer 33a functions as the main reference layer (MRL). The ferromagnetic layer 33b functions as the interface layer (IL) between the nonmagnetic layer 34 and the main reference layer (MRL).
[0063] The ferromagnetic layer 33a, for example, contains at least one element selected from iron (Fe), cobalt (Co), and nickel (Ni). Furthermore, the ferromagnetic layer 33a may contain at least one element selected from boron (B), phosphorus (P), carbon (C), aluminum (Al), silicon (Si), tantalum (Ta), molybdenum (Mo), chromium (Cr), hafnium (Hf), tungsten (W), and titanium (Ti) as an impurity. Specifically, the ferromagnetic layer 33a may contain cobalt iron boron (CoFeB). The ferromagnetic layer 33a may also contain at least one binary compound selected from iron boride (FeB), cobalt platinum (CoPt), cobalt nickel (CoNi), and cobalt palladium (CoPd). The ferromagnetic layer 33b, for example, may contain cobalt iron boron (CoFeB) or iron boride (FeB).
[0064] The non-magnetic layer 34 is a non-magnetic insulator. Together with the ferromagnetic layers 33 and 35, the non-magnetic layer 34 forms a magnetic tunnel junction. Specifically, the non-magnetic layer 34 functions as a tunnel barrier layer (TB) of the MTJ element. Furthermore, the non-magnetic layer 34 functions as a seed material during the crystallization process of the ferromagnetic layers 33 and 35 included in the manufacturing process of the magnetic storage device 1. This seed material corresponds to a material that serves as a nucleus for growing a crystalline film from the interface between the ferromagnetic layers 33 and 35. The non-magnetic layer 34, for example, includes an oxide of at least one element or compound selected from magnesium (Mg), aluminum (Al), zinc (Zn), titanium (Ti), and LSM (Lanthanum-Strontium-Manganese).
[0065] The ferromagnetic layer 35 is a ferromagnetic conductor. The ferromagnetic layer 35 has an easy magnetization axis oriented perpendicular to the film surface. The magnetization of the ferromagnetic layer 35 is directed toward either the ferromagnetic layer 33 or the nonmagnetic layer 36. The magnetization of the ferromagnetic layer 35 is configured to be easily reversible compared to the ferromagnetic layer 33. Consequently, the ferromagnetic layer 35 serves as the storage layer (SL) of the MTJ element. The storage layer (SL) is also referred to as the "free layer."
[0066] The ferromagnetic layer 35 may contain, for example, at least one element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). Furthermore, the ferromagnetic layer 35 may contain, as an impurity, at least one element selected from the group consisting of boron (B), phosphorus (P), carbon (C), aluminum (Al), silicon (Si), tantalum (Ta), molybdenum (Mo), chromium (Cr), hafnium (Hf), tungsten (W), and titanium (Ti). Specifically, the ferromagnetic layer 35 may contain cobalt iron boron (CoFeB) or iron boride (FeB).
[0067] The non-magnetic layer 36 is a non-magnetic oxide. The non-magnetic layer 36 serves as an oxide capping layer OxCP for the ferromagnetic layer 35 (storage layer SL). The non-magnetic layer 36 (oxide capping layer OxCP) is in contact with the ferromagnetic layer 35 (storage layer SL). The non-magnetic layer 36 can improve the perpendicular magnetic anisotropy of the ferromagnetic layer 35. The non-magnetic layer 36 includes an oxide, such as magnesium oxide (MgO), aluminum oxide (Al2O3), or a rare earth oxide. Alternatively, the non-magnetic layer 36 can be a mixture of these oxides. That is, the non-magnetic layer 36 is not limited to a binary compound formed from two elements, but can also include a ternary compound formed from three elements, such as magnesium aluminum oxide (MgAl2O4). In addition, the non-magnetic layer 36 includes, for example, at least one element selected from iridium (Ir), platinum (Pt), and ruthenium (Ru).
[0068] The non-magnetic layer 37 is a non-magnetic conductor. The non-magnetic layer 37 serves as a metal cover layer MCP for the ferromagnetic layer 35 (storage layer SL). The non-magnetic layer 37 includes non-magnetic layers 37a, 37b, and 37c. The non-magnetic layer 37a is disposed above the non-magnetic layer 36. The non-magnetic layer 37b is disposed above the non-magnetic layer 37a. The non-magnetic layer 37c is disposed above the non-magnetic layer 37b. In other words, the non-magnetic layer 37a is disposed between the non-magnetic layer 36 and the non-magnetic layer 37b. The non-magnetic layer 37b is disposed between the non-magnetic layer 37a and the non-magnetic layer 37c. Hereinafter, the non-magnetic layers 37a, 37b, and 37c are also referred to as the first metal cover layer MCP1, the second metal cover layer MCP2, and the third metal cover layer MCP3, respectively.
[0069] The non-magnetic layer 37a (first metal cover layer MCP1) and 37b (second metal cover layer MCP2) can, for example, have the function of improving the characteristics of the MTJ element, function as a hard mask, and / or function as an electrode. The non-magnetic layer 37a includes, for example, tantalum (Ta). The non-magnetic layer 37b includes, for example, a compound (HfB) of hafnium (Hf) and boron (B), or hafnium (Hf). By making the non-magnetic layer 37b include a hard material, i.e., a material with high hardness, such as a hafnium boron compound (HfB) or hafnium (Hf), the defect rate in the MTJ element can be reduced.
[0070] The non-magnetic layer 37c (third metal cap layer MCP3) can be used as an electrode to improve the electrical connectivity between the variable resistance element VR and an upper element (e.g., the switching element SE) or a conductive layer (e.g., the bit line BL) 20. The non-magnetic layer 37c contains at least one element selected from ruthenium (Ru), platinum (Pt), tungsten (W), and tantalum (Ta).
[0071] The variable resistor element VR described above functions as a perpendicular magnetization MTJ element utilizing the TMR (Tunneling Magnetoresistance) effect. The variable resistor element VR can be in either a low resistance state or a high resistance state depending on the relative relationship between the magnetization directions of the ferromagnetic layer 33 (reference layer RL) and the ferromagnetic layer 35 (storage layer SL). Specifically, the variable resistor element VR is in a high resistance state when the magnetization directions of the reference layer RL and the storage layer SL are antiparallel (AP (Antiparallel) state), and is in a low resistance state when the magnetization directions of the reference layer RL and the storage layer SL are parallel (P (Parallel) state).
[0072] The magnetic storage device 1 can store desired data in the memory cell MC by fixing the magnetization direction of the ferromagnetic layer 33 (reference layer RL) and varying the magnetization direction of the ferromagnetic layer 35 (storage layer SL). Specifically, the magnetic storage device 1 injects spin torque into the storage layer SL and reference layer RL by passing a write current through the variable resistance element VR, thereby controlling the magnetization direction of the storage layer SL. This writing method is called "spin injection writing."
[0073] In this example, the variable resistance element VR enters the AP state when a write current flows from the ferromagnetic layer 33 toward the ferromagnetic layer 35, and enters the P state when a write current flows from the ferromagnetic layer 35 toward the ferromagnetic layer 33. Furthermore, the variable resistance element VR is configured so that the magnetization direction of the ferromagnetic layer 33 does not change when a current of a magnitude sufficient to reverse the magnetization direction of the ferromagnetic layer 35 flows through the variable resistance element VR. In other words, "the magnetization direction is fixed" means that the magnetization direction of the ferromagnetic layer 33 does not change in response to a current of a magnitude sufficient to reverse the magnetization direction of the ferromagnetic layer 35.
[0074] Furthermore, the variable resistance element VR may include other layers, and each ferromagnetic layer and each non-magnetic layer may be composed of a plurality of layers.
[0075] 1.2.4 Comparison of characteristics based on differences in metal coatings
[0076] Hereinafter, using Comparative Example 1 with respect to the first embodiment, a description will be given of changes in the characteristics of the variable resistance element VR (MTJ element) due to differences in the metal cover layer. Figure 5 It is a figure which shows the cross-sectional structure and characteristics of the metal coating layer in 1st Embodiment and Comparative Example 1. Figure 5The cross-sectional structure shown extracts and shows the ferromagnetic layer 35 (storage layer SL), the nonmagnetic layer 36 (cap layer OxCP), and the nonmagnetic layer 37 (metal cap layer MCP), which are layer structures corresponding to the variable resistance element VR formed on the silicon substrate.
[0077] like Figure 5 As shown, cobalt iron boron (CoFeB) is used for the ferromagnetic layer 35 (storage layer SL) in both the first embodiment and comparative example 1. Oxide is used for the nonmagnetic layer 36 (cap layer OxCP) in both the first embodiment and comparative example 1. In both the first embodiment and comparative example 1, the same material is used for the other layers except the nonmagnetic layer 37 (metal cap layer MCP).
[0078] The metal capping layers MCP of the first embodiment and comparative example 1 have different structures. In the first embodiment, a metal capping layer MCP1 containing tantalum (Ta), a metal capping layer MCP2 containing hafnium boron (HfB), and a metal capping layer MCP3 containing ruthenium (Ru) are sequentially provided above the capping layer OxCP. In comparative example 1, a metal capping layer MCP containing tantalum (Ta) and a metal capping layer MCP containing ruthenium (Ru) are sequentially provided above the capping layer OxCP.
[0079] The etching rate of the metal cap layer MCP2 containing the hafnium boron compound (HfB) in the first embodiment is approximately The etching rate of the metal cap layer MCP containing ruthenium (Ru) in Comparative Example 1 is about
[0080] The SFR (Shunt Fail Rate) in the memory cell MC of the magnetic storage device 1 according to the first embodiment is approximately 3.4%. In contrast, the SFR in the memory cell of Comparative Example 1 is approximately 79.9%. The SFR represents the rate of failure caused by a short circuit between the storage layer SL and the reference layer RL in the MTJ element.
[0081] As described above, the first embodiment including the metal cap layer MCP2 made of a hard material such as hafnium boron (HfB) can reduce the SFR in the memory cell MC compared to the comparative example 1 not including the metal cap layer HfB.
[0082] 1.3 Effects of the First Implementation
[0083] According to the magnetic storage device 1 of the first embodiment, the defect rate of the memory cell can be reduced, and the performance of the memory cell can be improved.
[0084] Hereinafter, the effects of the first embodiment will be described in detail.
[0085] One method for increasing the storage capacity of magnetic storage devices is to miniaturize memory cells MC and arrange them at a higher density by narrowing the pitch. With such miniaturization and narrowing the pitch of memory cells MC, the defect rate of memory cells MC in magnetic storage devices may increase. Therefore, it is desirable to reduce the SFR in magnetic storage devices.
[0086] In contrast, in the configuration of the first embodiment, a metal cap layer MCP2 containing a hafnium boron compound (HfB) or hafnium (Hf) is provided above the storage layer SL. This reduces the SFR in the memory cell MC. Consequently, the defect rate of the memory cell MC in the magnetic storage device can be reduced, thereby improving the performance of the memory cell.
[0087] 2. Second Implementation
[0088] Next, the magnetic storage device of the second embodiment is described. The configuration of the storage system, the circuit configuration of the memory cell array, and the structure of the memory cell array in the second embodiment are the same as those in the first embodiment described above. In subsequent embodiments, these configurations are also the same as those in the first embodiment, so description thereof is omitted. In the second embodiment, a variable resistance element VR is described that is different from that in the first embodiment. In the variable resistance element VR of the second embodiment, the non-magnetic layer 30 (buffer layer BL) contains silicon (Si), and the non-magnetic layer 37 (metal cover layer MCP) contains molybdenum (Mo).
[0089] 2.1 Cross-sectional structure of variable resistor element
[0090] Below, refer to Figure 6 A cross-sectional structure of the variable resistance element VR according to the second embodiment will be described. Figure 6 It is a cross-sectional view of a variable resistance element VR included in a memory cell MC of the magnetic memory device 1 according to the second embodiment.
[0091] like Figure 6 As shown, the variable resistance element VR includes, for example, a nonmagnetic layer 30, a ferromagnetic layer 31, a nonmagnetic layer 32, a ferromagnetic layer 33, a nonmagnetic layer 34, a ferromagnetic layer 35, a nonmagnetic layer 36, and a nonmagnetic layer 37. Hereinafter, descriptions of the same layers as those in the first embodiment will be omitted, and the description will focus on the layers having different structures and materials from those in the first embodiment.
[0092] The nonmagnetic layer 30 is a nonmagnetic conductor. The nonmagnetic layer (buffer layer BL) 30 functions as a layer for controlling the ferromagnetic layer 31 formed thereon to a desired crystal orientation, and as a layer for suppressing material diffusion into the ferromagnetic layer 31. The nonmagnetic layer 30 includes a first layer 30a, a second layer 30b, and a third layer 30c. The second layer 30b is provided above the first layer 30a. The third layer 30c is provided above the second layer 30b. In other words, the second layer 30b is provided between the first layer 30a and the third layer 30c. The third layer 30c is provided between the second layer 30b and the ferromagnetic layer 31.
[0093] The first layer 30a has an amorphous structure and contains hafnium (Hf) or hafnium boron (HfB).
[0094] The second layer 30b has a BCC (body centered cubic) crystal structure and has a
[110] plane of the BCC crystal structure in a direction perpendicular to the stacking direction of the stacking structure
[100] . By using such a second layer 30b, the ferromagnetic layer 31 can be well oriented in the FCC (face centered cubic)
[111] plane or the HCP (hexagonal close packed)
[0001] plane. As a result, the perpendicular magnetic anisotropy of the ferromagnetic layer 31 can be improved. The second layer 30b can contain at least one element selected from molybdenum (Mo), tungsten (W), and tantalum (Ta). That is, the second layer 30b can be a molybdenum (Mo) layer, a tungsten (W) layer, or a tantalum (Ta). The second layer 30b can also be an alloy layer of two or more elements selected from molybdenum (Mo), tungsten (W), and tantalum (Ta).
[0095] The third layer 30c contains silicon (Si) or a silicon compound. For example, the third layer 30c is a layer containing silicon (Si) and boron (B). By providing the third layer 30c, the diffusion of elements caused by heat treatment can be suppressed, and a variable resistance element VR with excellent heat resistance can be obtained. In other words, the degradation of characteristics caused by heat treatment can be suppressed, and the magnetoresistance change rate (MR ratio) in the MTJ element of the variable resistance element VR can be increased. The MR ratio is the value obtained by dividing the change in resistance when the MTJ element changes from the P state to the AP state by the resistance in the P state. In addition, by providing the third layer 30c, the perpendicular magnetic anisotropy of the ferromagnetic layer 31 can be improved.
[0096] In addition, the non-magnetic layer 30 is Figure 6 In the example shown, three layers are shown, but a laminated body in which two or four or more layers are laminated may also be used.
[0097] The nonmagnetic layer 36 is a nonmagnetic oxide. It serves as an oxide capping layer OxCP for the ferromagnetic layer 35 (storage layer SL). The nonmagnetic layer 36 is in contact with the ferromagnetic layer 35. The nonmagnetic layer 36 can improve the perpendicular magnetic anisotropy of the ferromagnetic layer 35. The nonmagnetic layer 36 may include an oxide such as gadolinium oxide (GdOx), aluminum oxide (Al2O3), or a rare earth oxide. Alternatively, the nonmagnetic layer 36 may be a mixture of these oxides.
[0098] The nonmagnetic layer 37 is a nonmagnetic conductor. It serves as a metal cap layer MCP for the ferromagnetic layer 35 (storage layer SL). The nonmagnetic layer 37 can, for example, improve the characteristics of the MTJ element, serve as a hard mask, and / or function as an electrode. The nonmagnetic layer 37 includes, for example, molybdenum (Mo).
[0099] When the nonmagnetic layer 30 (buffer layer BL) includes silicon (Si) or a silicon compound and the nonmagnetic layer 37 (metal cap layer MCP) includes molybdenum (Mo), the magnetoresistance change ratio (MR ratio) in the MTJ element is further increased.
[0100] 2.2 Comparison of properties based on differences in metal cover and buffer layers
[0101] Hereinafter, using Comparative Example 2-4 with respect to the second embodiment, a description will be given of changes in the characteristics of the variable resistance element VR (MTJ element) due to differences in the metal cap layer and the buffer layer. Figure 7 It is a diagram showing the cross-sectional structure of the metal coating layer and the buffer layer in the second embodiment and comparative example 2-4. Figure 7 The cross-sectional structure shown extracts and shows the nonmagnetic layer 30 (buffer layer BL), ferromagnetic layer 35 (storage layer SL), nonmagnetic layer 36 (cover layer OxCP), and nonmagnetic layer 37 (metal cover layer MCP) of the layer structure corresponding to the variable resistance element VR.
[0102] like Figure 7 As shown, cobalt iron boron (CoFeB) is used for the ferromagnetic layer 35 (storage layer SL) in the second embodiment and comparative example 2-4. Gadolinium oxide (GdOx) is used for the nonmagnetic layer 36 (cap layer OxCP) in the second embodiment and comparative example 2-4. In the second embodiment and comparative example 2-4, the same materials are used for the other layers except for the nonmagnetic layer 30 (buffer layer BL) and the nonmagnetic layer 37 (metal cap layer MCP).
[0103] In the second embodiment, a metal cap layer MCP containing molybdenum (Mo) is provided above the cap layer OxCP, and a buffer layer BL containing silicon (Si) is provided below the transition canceling layer SCL.
[0104] In Comparative Example 2, a metal cap layer MCP containing ruthenium (Ru) and a metal cap layer MCP containing tantalum (Ta) are sequentially provided above the cap layer OxCP. Furthermore, the buffer layer BL provided below the transition canceling layer SCL does not contain silicon (Si).
[0105] In Comparative Example 3, similar to Comparative Example 2, a metal cap layer MCP containing ruthenium (Ru) and a metal cap layer MCP containing tantalum (Ta) are sequentially provided above the cap layer OxCP. Furthermore, a buffer layer BL containing silicon (Si) is provided below the transition canceling layer SCL.
[0106] In Comparative Example 4, a metal cap layer MCP containing molybdenum (Mo) is provided on the cap layer OxCP, and the buffer layer BL provided below the transition canceling layer SCL does not contain silicon (Si).
[0107] Below, refer to Figure 8 The magnetic resistance change rate in the second embodiment and comparative example 2-4 will be described. Figure 8 Graph showing the relationship between the exchange coupling magnetic field and the magnetoresistance change rate in the second embodiment and comparative example 2-4. Figure 8 In FIG. 1 , the horizontal axis represents the exchange coupling magnetic field (Hex) (kOe), and the vertical axis represents the magnetoresistance change rate (%). The exchange coupling magnetic field represents the intensity of the pinned magnetic field of the reference layer RL in the SAF structure composed of the transition cancel layer SCL and the reference layer RL.
[0108] In Comparative Example 2, the buffer layer BL does not contain silicon (Si), and the metal cap layer MCP does not contain molybdenum (Mo). Figure 8 As shown, compared with the second embodiment and Comparative Example 3, the exchange coupling magnetic field is weak and the magnetoresistance change rate is also small.
[0109] In Comparative Example 3, the buffer layer BL includes silicon (Si), and the metal cap layer MCP does not include molybdenum (Mo). Figure 8 As shown, the exchange coupling magnetic field is stronger than that of Comparative Examples 2 and 4, and weaker than that of the second embodiment, and the magnetoresistance change rate is also smaller.
[0110] In Comparative Example 4, the buffer layer BL does not include silicon (Si), and the metal cap layer MCP includes molybdenum (Mo). Figure 8 As shown, compared with the second embodiment and Comparative Example 3, the exchange coupling magnetic field is weak and the magnetoresistance change rate is also small.
[0111] In the second embodiment, the buffer layer BL includes silicon (Si), and the metal cap layer MCP includes molybdenum (Mo). Figure 8 As shown, the exchange coupling magnetic field is stronger and the magnetoresistance change rate is larger than that of Comparative Example 2-4.
[0112] More specifically, in the second embodiment, the inclusion of a buffer layer BL containing silicon (Si) improves the heat resistance of the transition cancellation layer SCL and reference layer RL, which form the SAF structure. Furthermore, the inclusion of a metal cap layer MCP containing molybdenum (Mo) improves the heat resistance of the storage layer SL. Consequently, in the variable resistance element VR of the second embodiment, both the exchange coupling magnetic field and the magnetoresistance change rate can be improved.
[0113] 2.3 Effects of the Second Implementation
[0114] According to the magnetic storage device 1 of the second embodiment, the performance of the storage cell can be improved.
[0115] Hereinafter, the effects of the second embodiment will be described in detail.
[0116] One method for increasing the storage capacity of a magnetic storage device is to miniaturize the memory cells MC and arrange them at a higher density by narrowing the pitch. With the miniaturization and narrowing of the pitch of the memory cells MC, the magnetoresistance change rate in the memory cells MC may decrease. Therefore, it is desirable to increase the magnetoresistance change rate in the memory cells MC.
[0117] In contrast, the configuration of the second embodiment includes a buffer layer BL made of silicon (Si) below the transition cancellation layer SCL, and a metal cap layer MCP made of molybdenum (Mo) above the storage layer SL. This increases the magnetoresistance change rate while maintaining the strength of the exchange coupling magnetic field. Consequently, the performance of the memory cell MC in the magnetic storage device can be improved.
[0118] 3. Third Implementation Method
[0119] Next, a magnetic storage device according to a third embodiment will be described. In the third embodiment, a variable resistance element VR is described, which differs from the first and second embodiments. In the variable resistance element VR according to the third embodiment, the nonmagnetic layer 36 (cover layer OxCP) contains magnesium oxide (MgO), and the nonmagnetic layer 37 (metal cover layer MCP) contains molybdenum (Mo).
[0120] 3.1 Cross-sectional structure of variable resistor element
[0121] Below, refer to Figure 9 A cross-sectional structure of the variable resistance element VR according to the third embodiment will be described. Figure 9It is a cross-sectional view of a variable resistance element VR included in a memory cell MC of a magnetic memory device 1 according to the third embodiment.
[0122] like Figure 9 As shown, the variable resistance element VR includes, for example, a nonmagnetic layer 30, a ferromagnetic layer 31, a nonmagnetic layer 32, a ferromagnetic layer 33, a nonmagnetic layer 34, a ferromagnetic layer 35, a nonmagnetic layer 36, and a nonmagnetic layer 37. Hereinafter, descriptions of the same layers as those in the first embodiment will be omitted, and the description will focus on the layers having different structures and materials from those in the first embodiment.
[0123] The nonmagnetic layer 36 is a nonmagnetic oxide. It serves as an oxide cap layer OxCP for the ferromagnetic layer 35 (storage layer SL). The nonmagnetic layer 36 is in contact with the ferromagnetic layer 35. The nonmagnetic layer 36 can improve the perpendicular magnetic anisotropy of the ferromagnetic layer 35. For example, the nonmagnetic layer 36 includes magnesium oxide (MgO).
[0124] The nonmagnetic layer 37 is a nonmagnetic conductor. It serves as a metal cap layer MCP for the ferromagnetic layer 35 (storage layer SL). The nonmagnetic layer 37 can, for example, improve the characteristics of the MTJ element, serve as a hard mask, or function as an electrode. The nonmagnetic layer 37 includes, for example, molybdenum (Mo).
[0125] The nonmagnetic layer 36 (cap layer OxCP) includes magnesium oxide (MgO) and the nonmagnetic layer 37 (metal cap layer MCP) includes molybdenum (Mo), thereby increasing the anisotropic magnetic field of the storage layer SL in the MTJ element.
[0126] 3.2 Comparison of properties based on differences between metal and oxide coatings
[0127] Hereinafter, using Comparative Examples 5-7 with respect to the third embodiment, a description will be given of changes in the characteristics of the variable resistance element VR (MTJ element) due to the difference between the metal cap layer and the oxide cap layer. Figure 10 These are diagrams showing the cross-sectional structures and characteristics of the metal covering layer and the oxide covering layer in the third embodiment and comparative examples 5-7. Figure 10 The cross-sectional structure shown extracts and shows the ferromagnetic layer 35 (storage layer SL), the nonmagnetic layer 36 (cap layer OxCP), and the nonmagnetic layer 37 (metal cap layer MCP), which are layer structures corresponding to the variable resistance element VR.
[0128] like Figure 10As shown, cobalt iron boron (CoFeB) is used for the ferromagnetic layer 35 (storage layer SL) in the third embodiment and comparative examples 5 to 7. In the third embodiment and comparative examples 5 to 7, the same material is used for the other layers except for the non-magnetic layer 36 (cap layer OxCP) and the non-magnetic layer 37 (metal cap layer MCP).
[0129] In the third embodiment, a cap layer OxCP made of magnesium oxide (MgO) is provided on the storage layer SL, and a metal cap layer MCP made of molybdenum (Mo) is provided on the cap layer OxCP.
[0130] In Comparative Example 5, a cap layer OxCP containing gadolinium oxide (GdOx) is provided above the storage layer SL. Furthermore, a metal cap layer MCP containing ruthenium (Ru) and a metal cap layer MCP containing tantalum (Ta) are sequentially provided above the cap layer OxCP.
[0131] In Comparative Example 6, a cap layer OxCP containing magnesium oxide (MgO) is provided above the storage layer SL, and a metal cap layer MCP containing ruthenium (Ru) and a metal cap layer MCP containing tantalum (Ta) are sequentially provided above the cap layer OxCP.
[0132] In Comparative Example 7, a cap layer OxCP containing gadolinium oxide (GdOx) is provided above the storage layer SL, and a metal cap layer MCP containing molybdenum (Mo) is provided above the cap layer OxCP.
[0133] like Figure 10 As shown, the anisotropic magnetic field of the storage layer SL in the third embodiment is approximately 5.5 (kOe). The anisotropic magnetic fields of the storage layer SL in Comparative Examples 5, 6, and 7 are approximately 3.1 (kOe), 3.2 (kOe), and 2.2 (kOe), respectively. These anisotropic magnetic fields are values obtained when the product of the saturation magnetic field of the storage layer SL and its film thickness (i.e., thickness in the Z direction) is constant.
[0134] In both Comparative Examples 5 and 6, the metal cap layer MCP includes a layer containing ruthenium (Ru) and a layer containing tantalum (Ta). In Comparative Example 5, the cap layer OxCP includes gadolinium oxide (GdOx), while in Comparative Example 6, the cap layer OxCP includes magnesium oxide (MgO). The anisotropic magnetic fields of the storage layers SL in Comparative Examples 5 and 6 with these structures are substantially the same and cannot be increased.
[0135] In the third embodiment, by providing a cap layer OxCP containing magnesium oxide (MgO) and a metal cap layer MCP containing molybdenum (Mo), the anisotropic magnetic field of the storage layer SL can be increased compared to Comparative Examples 5 to 7. Furthermore, even if a metal cap layer MCP containing molybdenum (Mo) is provided as in Comparative Example 7, the anisotropic magnetic field of the storage layer SL cannot be increased without the cap layer OxCP containing magnesium oxide (MgO).
[0136] 3.3 Effects of the Third Implementation
[0137] According to the magnetic storage device 1 of the third embodiment, the performance of the storage cell can be improved.
[0138] Hereinafter, the effects of the third embodiment will be described in detail.
[0139] One method for increasing the storage capacity of magnetic storage devices is to miniaturize memory cells MC and arrange them at a higher density by narrowing the pitch. However, with such miniaturization and narrowing of the pitch of memory cells MC, the thermal stability of the memory cells MC may decrease. Therefore, there is a need to improve the thermal stability of the memory cells MC.
[0140] In contrast, in the configuration of the third embodiment, a cap layer OxCP made of magnesium oxide (MgO) is provided above the storage layer SL, and a metal cap layer MCP made of molybdenum (Mo) is provided above the cap layer OxCP. This increases the anisotropic magnetic field of the storage layer SL. Consequently, the thermal stability of the memory cell can be improved, thereby enhancing the performance of the memory cell.
[0141] 4. Fourth Implementation Method
[0142] Next, a magnetic storage device according to a fourth embodiment will be described. In the fourth embodiment, a variable resistance element VR having the configurations described in the first, second, and third embodiments will be described.
[0143] In the variable resistance element VR of the fourth embodiment, the non-magnetic layer 30 (buffer layer BL) contains silicon (Si), the non-magnetic layer 36 (cover layer OxCP) contains magnesium oxide (MgO), the non-magnetic layer 37a (metal cover layer MCP1) contains molybdenum (Mo), the non-magnetic layer 37b (metal cover layer MCP2) contains hafnium boron compound (HfB) or hafnium (Hf), and the non-magnetic layer 37c (metal cover layer MCP3) contains ruthenium (Ru).
[0144] 4.1 Cross-sectional structure of variable resistor element
[0145] Below, refer to Figure 11 A cross-sectional structure of the variable resistance element VR according to the fourth embodiment will be described. Figure 11 It is a cross-sectional view of a variable resistance element VR included in a memory cell MC of a magnetic memory device 1 according to a fourth embodiment.
[0146] like Figure 11 As shown, the variable resistance element VR includes, for example, a nonmagnetic layer 30, a ferromagnetic layer 31, a nonmagnetic layer 32, a ferromagnetic layer 33, a nonmagnetic layer 34, a ferromagnetic layer 35, a nonmagnetic layer 36, a nonmagnetic layer 37a, a nonmagnetic layer 37b, and a nonmagnetic layer 37c.
[0147] The non-magnetic layer 30, the ferromagnetic layer 31, the non-magnetic layer 32, the ferromagnetic layer 33, the non-magnetic layer 34, the ferromagnetic layer 35, the non-magnetic layer 36, the non-magnetic layer 37a, the non-magnetic layer 37b, and the non-magnetic layer 37c are stacked in this order from the conductive layer 20 (bit line BL) side toward the conductive layer 21 (word line WL) side (in the Z direction).
[0148] Specifically, the non-magnetic layer 30 is provided above the conductive layer 20 (in the Z direction). The ferromagnetic layer 31 is provided above the non-magnetic layer 30. The non-magnetic layer 32 is provided above the ferromagnetic layer 31. The ferromagnetic layer 33 is provided above the non-magnetic layer 32. The non-magnetic layer 34 is provided above the ferromagnetic layer 33. The ferromagnetic layer 35 is provided above the non-magnetic layer 34. The non-magnetic layer 36 is provided above the ferromagnetic layer 35. The non-magnetic layer 37a is provided above the non-magnetic layer 36. The non-magnetic layer 37b is provided above the non-magnetic layer 37a. The non-magnetic layer 37c is provided above the non-magnetic layer 37b. The conductive layer 21 is provided above the non-magnetic layer 37c.
[0149] In other words, the ferromagnetic layer 33 is provided between the ferromagnetic layer 31 and the ferromagnetic layer 35. The nonmagnetic layer 34 is provided between the ferromagnetic layer 33 and the ferromagnetic layer 35. The nonmagnetic layer 32 is provided between the ferromagnetic layer 31 and the ferromagnetic layer 33. The ferromagnetic layer 31 is provided between the nonmagnetic layer 30 and the nonmagnetic layer 32. The nonmagnetic layer 30 is provided between the conductive layer 20 and the ferromagnetic layer 31. The ferromagnetic layer 35 is provided between the nonmagnetic layer 34 and the nonmagnetic layer 36. The nonmagnetic layer 36 is provided between the ferromagnetic layer 35 and the nonmagnetic layer 37a. The nonmagnetic layer 37a is provided between the nonmagnetic layer 36 and the nonmagnetic layer 37b. The nonmagnetic layer 37b is provided between the nonmagnetic layer 37a and the nonmagnetic layer 37c. The nonmagnetic layer 37c is provided between the nonmagnetic layer 37b and the conductive layer 21.
[0150] Non-magnetic layer 30 comprises, for example, silicon (Si). Non-magnetic layer 36 (cover layer OxCP) comprises, for example, magnesium oxide (MgO). Non-magnetic layer 37a (metal cover layer MCP1) comprises, for example, molybdenum (Mo). Non-magnetic layer 37b (metal cover layer MCP2) comprises, for example, hafnium boron (HfB) or hafnium (Hf). Non-magnetic layer 37c (metal cover layer MCP3) comprises, for example, ruthenium (Ru).
[0151] In addition, the effects of the fourth embodiment are substantially the same as those of the first, second, and third embodiments, and thus description thereof is omitted.
[0152] 5. Fifth Implementation Method
[0153] Next, a magnetic storage device according to a fifth embodiment will be described. In the fifth embodiment, a variable resistance element VR having the configuration described in the first and second embodiments will be described.
[0154] In the variable resistance element VR of the fifth embodiment, the non-magnetic layer 30 (buffer layer BL) contains silicon (Si), the non-magnetic layer 37a (metal cover layer MCP1) contains molybdenum (Mo), the non-magnetic layer 37b (metal cover layer MCP2) contains hafnium boron compound (HfB) or hafnium (Hf), and the non-magnetic layer 37c (metal cover layer MCP3) contains ruthenium (Ru).
[0155] 5.1 Cross-sectional structure of variable resistor element
[0156] Below, refer to Figure 12 A cross-sectional structure of the variable resistance element VR according to the fifth embodiment will be described. Figure 12 It is a cross-sectional view of a variable resistance element VR included in a memory cell MC of a magnetic memory device 1 according to the fifth embodiment.
[0157] Figure 12 The stacked structure of the fifth embodiment shown is Figure 11 The same is true for the fourth embodiment shown. The non-magnetic layer 36 (cover layer OxCP) contains, for example, gadolinium oxide (GdOx). The configuration and materials of the other ferromagnetic layers and non-magnetic layers are the same as those of the fourth embodiment.
[0158] The effects of the fifth embodiment are substantially the same as those of the first and second embodiments, and thus description thereof is omitted.
[0159] 6. Sixth Implementation Method
[0160] Next, a magnetic storage device according to a sixth embodiment will be described. In the sixth embodiment, a variable resistance element VR having the configuration described in the second and third embodiments will be described.
[0161] In the variable resistance element VR of the sixth embodiment, the nonmagnetic layer 30 (buffer layer BL) includes silicon (Si), the nonmagnetic layer 36 (cap layer OxCP) includes magnesium oxide (MgO), and the nonmagnetic layer 37 (metal cap layer MCP) includes molybdenum (Mo).
[0162] 6.1 Cross-sectional structure of variable resistor element
[0163] Below, refer to Figure 13 A cross-sectional structure of the variable resistance element VR according to the sixth embodiment will be described. Figure 13 It is a cross-sectional view of a variable resistance element VR included in a memory cell MC of a magnetic memory device 1 according to the sixth embodiment.
[0164] like Figure 13 As shown, the variable resistance element VR includes, for example, a nonmagnetic layer 30 , a ferromagnetic layer 31 , a nonmagnetic layer 32 , a ferromagnetic layer 33 , a nonmagnetic layer 34 , a ferromagnetic layer 35 , a nonmagnetic layer 36 , and a nonmagnetic layer 37 .
[0165] The non-magnetic layer 30, the ferromagnetic layer 31, the non-magnetic layer 32, the ferromagnetic layer 33, the non-magnetic layer 34, the ferromagnetic layer 35, the non-magnetic layer 36, and the non-magnetic layer 37 are stacked in this order from the conductive layer 20 (bit line BL) side toward the conductive layer 21 (word line WL) side (in the Z direction).
[0166] Specifically, the nonmagnetic layer 30 is provided above the conductive layer 20 (in the Z direction). The ferromagnetic layer 31 is provided above the nonmagnetic layer 30. The nonmagnetic layer 32 is provided above the ferromagnetic layer 31. The ferromagnetic layer 33 is provided above the nonmagnetic layer 32. The nonmagnetic layer 34 is provided above the ferromagnetic layer 33. The ferromagnetic layer 35 is provided above the nonmagnetic layer 34. The nonmagnetic layer 36 is provided above the ferromagnetic layer 35. The nonmagnetic layer 37 is provided above the nonmagnetic layer 36. The conductive layer 21 is provided above the nonmagnetic layer 37.
[0167] In other words, the ferromagnetic layer 33 is provided between the ferromagnetic layer 31 and the ferromagnetic layer 35. The nonmagnetic layer 34 is provided between the ferromagnetic layer 33 and the ferromagnetic layer 35. The nonmagnetic layer 32 is provided between the ferromagnetic layer 31 and the ferromagnetic layer 33. The ferromagnetic layer 31 is provided between the nonmagnetic layer 30 and the nonmagnetic layer 32. The nonmagnetic layer 30 is provided between the conductive layer 20 and the ferromagnetic layer 31. The ferromagnetic layer 35 is provided between the nonmagnetic layer 34 and the nonmagnetic layer 36. The nonmagnetic layer 36 is provided between the ferromagnetic layer 35 and the nonmagnetic layer 37. The nonmagnetic layer 37 is provided between the nonmagnetic layer 36 and the conductive layer 21.
[0168] The non-magnetic layer 30 includes, for example, silicon (Si). The non-magnetic layer 36 (cover layer OxCP) includes, for example, magnesium oxide (MgO). The non-magnetic layer 37 (metal cover layer MCP) includes, for example, molybdenum (Mo).
[0169] In addition, since the effects of the sixth embodiment are substantially the same as those of the second and third embodiments, description thereof will be omitted.
[0170] 7. Others
[0171] In the embodiments, the magnetic storage device 1 is described as an example of a magnetic device including an MTJ element (variable resistance element VR), but the present invention is not limited thereto. The magnetic device may also be other equipment such as a sensor or a medium that requires a magnetic element having perpendicular magnetic anisotropy. The magnetic element may at least use a variable resistance element VR.
[0172] In this specification, "connection" means electrical connection, and does not exclude the situation where another element is passed between them. The non-magnetic layers 32 and 37 can each be referred to as a "conductor layer". The non-magnetic layer 34 can also be referred to as an "oxide layer". The non-magnetic layer 36 can also be referred to as an "oxide layer". The elements contained in each layer of the MTJ element can be measured, for example, by using electron energy loss spectroscopy (EELS; Electron Energy Loss Spectroscopy) performed by a scanning transmission electron microscope (STEM; Scanning Transmission Electron Microscope).
[0173] While some embodiments of the present invention have been described, these embodiments are provided as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways and can be omitted, replaced, or modified without departing from the gist of the invention. These embodiments and their variations are included within the scope and gist of the invention and are also included within the scope of the invention described in the claims and their equivalents.
Claims
1. A magnetic storage device, include: a first non-magnetic layer comprising silicon; a first ferromagnetic layer disposed above the first non-magnetic layer; a second non-magnetic layer disposed above the first ferromagnetic layer; a second ferromagnetic layer disposed above the second non-magnetic layer; a third non-magnetic layer disposed above the second ferromagnetic layer; a third ferromagnetic layer, disposed above the third non-magnetic layer; a fourth non-magnetic layer disposed on the third ferromagnetic layer and comprising magnesium and oxygen; a fifth non-magnetic layer disposed on the fourth non-magnetic layer and comprising molybdenum; a sixth non-magnetic layer disposed on the fifth non-magnetic layer and comprising hafnium; and The seventh non-magnetic layer is disposed on the sixth non-magnetic layer and contains ruthenium.
2. The magnetic storage device according to claim 1, The fourth non-magnetic layer contains at least one element selected from the group consisting of iridium, platinum, and ruthenium.
3. The magnetic storage device according to claim 1, The first non-magnetic layer contains a silicon compound.
4. The magnetic storage device according to claim 1, The seventh non-magnetic layer includes at least one element selected from platinum, tungsten, tantalum, and ruthenium.
5. The magnetic storage device according to claim 1, The sixth non-magnetic layer includes a compound of hafnium and boron.
6. The magnetic storage device according to claim 1, The fifth non-magnetic layer contains a molybdenum compound.
7. The magnetic storage device according to claim 1, The third ferromagnetic layer is in contact with the fourth non-magnetic layer.
8. The magnetic storage device according to claim 1, The second ferromagnetic layer contains at least one element selected from iron, cobalt and nickel. The third non-magnetic layer comprises an oxide of at least one element or compound selected from magnesium, aluminum, zinc, titanium, and LSM (lanthanum strontium manganese). The third ferromagnetic layer contains at least one element selected from the group consisting of iron, cobalt, and nickel.
9. The magnetic storage device according to claim 1, The second non-magnetic layer is antiferromagnetically coupled to the first ferromagnetic layer. The magnetization direction of the first ferromagnetic layer is fixed in an antiparallel direction with respect to the magnetization direction of the second ferromagnetic layer.
10. The magnetic storage device according to claim 1, The first ferromagnetic layer contains at least one element selected from the group consisting of iron, cobalt, and nickel.
11. The magnetic storage device according to claim 1, The second non-magnetic layer contains at least one element selected from the group consisting of ruthenium, osmium, iridium, vanadium, and chromium.
12. The magnetic storage device according to claim 1, The second ferromagnetic layer and the third ferromagnetic layer each have an easy magnetization axis direction perpendicular to the film surface. The magnetization direction of the second ferromagnetic layer is fixed. The magnetization direction of the third ferromagnetic layer is configured to be more easily reversed than that of the second ferromagnetic layer.
13. The magnetic storage device according to claim 1, Also includes: A first conductive layer extending in a first direction; a second conductive layer extending in a second direction intersecting the first direction and spaced apart from the first conductive layer; as well as A memory cell is provided between the first conductive layer and the second conductive layer. The storage unit includes the first ferromagnetic layer, the second ferromagnetic layer, the third ferromagnetic layer, the first nonmagnetic layer, the second nonmagnetic layer, the third nonmagnetic layer, the fourth nonmagnetic layer, the fifth nonmagnetic layer, the sixth nonmagnetic layer and the seventh nonmagnetic layer.
14. A magnetic storage device, include: a first non-magnetic layer comprising silicon; a first ferromagnetic layer disposed above the first non-magnetic layer; a second non-magnetic layer disposed above the first ferromagnetic layer; a second ferromagnetic layer disposed above the second non-magnetic layer; a third non-magnetic layer disposed above the second ferromagnetic layer; a third ferromagnetic layer, disposed above the third non-magnetic layer; a fourth non-magnetic layer disposed above the third ferromagnetic layer; a fifth non-magnetic layer disposed on the fourth non-magnetic layer and comprising molybdenum; a sixth non-magnetic layer disposed on the fifth non-magnetic layer and comprising hafnium; and The seventh non-magnetic layer is disposed on the sixth non-magnetic layer and contains ruthenium.
15. The magnetic storage device according to claim 14, The first non-magnetic layer contains a silicon compound.
16. The magnetic storage device according to claim 14, The sixth non-magnetic layer includes a compound of hafnium and boron.
17. The magnetic storage device according to claim 14, The fifth non-magnetic layer contains a molybdenum compound.
18. A magnetic storage device, include: a first non-magnetic layer comprising silicon; a first ferromagnetic layer disposed above the first non-magnetic layer; a second non-magnetic layer disposed above the first ferromagnetic layer; a second ferromagnetic layer disposed above the second non-magnetic layer; a third non-magnetic layer disposed above the second ferromagnetic layer; a third ferromagnetic layer, disposed above the third non-magnetic layer; a fourth non-magnetic layer provided on the third ferromagnetic layer and containing magnesium and oxygen; and a fifth non-magnetic layer provided on the fourth non-magnetic layer and containing molybdenum.
19. The magnetic storage device according to claim 18, The first non-magnetic layer contains a silicon compound.
20. The magnetic storage device according to claim 18, The fifth non-magnetic layer contains a molybdenum compound.