Magnetic storage device
The magnetic memory device addresses the issue of high defect rates in miniaturized cells by using a silicon-containing buffer layer and molybdenum metal cap layer, improving cell stability and performance.
Patent Information
- Application Number
- JP2024040336
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-14
- Publication Date
- 2025-09-29
AI Technical Summary
Existing magnetic memory devices face challenges in reducing the defect rate of memory cells, particularly as they are miniaturized for higher density, leading to increased shunt failure rates.
The magnetic memory device incorporates a specific layer structure including a non-magnetic layer containing silicon or a silicon compound and a metal cap layer made of molybdenum, which enhances the perpendicular magnetic anisotropy and reduces shunt failure rates by improving the stability and integrity of the memory cells.
This configuration reduces the defect rate of memory cells, enhancing their performance and reliability, especially in high-density memory applications.
Smart Images
Figure 2025140766000001_ABST
Abstract
Description
[Technical Field]
[0001] FIELD OF THE INVENTION The present invention relates to a magnetic storage device. [Background technology]
[0002] 2. Description of the Related Art Magnetic storage devices using magnetoresistive elements as storage elements (Magnetoresistive Random Access Memories (MRAMs)) are known. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] US Patent Application Publication No. 2015 / 0092481 Summary of the Invention [Problem to be solved by the invention]
[0004] A magnetic memory device capable of improving the performance of memory cells is provided. [Means for solving the problem]
[0005] The magnetic memory device of the embodiment includes a first non-magnetic layer containing silicon (Si), a first ferromagnetic layer provided above the first non-magnetic layer, a second non-magnetic layer provided above the first ferromagnetic layer, a second ferromagnetic layer provided above the second non-magnetic layer, a third non-magnetic layer provided above the second ferromagnetic layer, a third ferromagnetic layer provided above the third non-magnetic layer, a fourth non-magnetic layer provided above the third ferromagnetic layer and containing magnesium (Mg) and oxide, a fifth non-magnetic layer provided above the fourth non-magnetic layer and containing molybdenum (Mo), a sixth non-magnetic layer provided above the fifth non-magnetic layer and containing hafnium (Hf), and a seventh non-magnetic layer provided above the sixth non-magnetic layer and containing ruthenium (Ru). [Brief explanation of the drawings]
[0006] [Figure 1] 1 is a block diagram showing the configuration of a memory system including a magnetic memory device according to a first embodiment. [Figure 2] 1 is a circuit diagram of a memory cell array of a magnetic memory device according to a first embodiment. [Figure 3] 1 is a perspective view showing the structure of a memory cell array of a magnetic memory device according to a first embodiment. [Figure 4] FIG. 2 is a cross-sectional view of a variable resistance element of the magnetic memory device according to the first embodiment. [Figure 5] 3A and 3B are diagrams showing the cross-sectional structures and characteristics of metal cap layers in the first embodiment and Comparative Example 1. [Figure 6] FIG. 10 is a cross-sectional view of a variable resistance element of a magnetic memory device according to a second embodiment. [Figure 7] 10A and 10B are diagrams showing cross-sectional structures of a metal cap layer and a buffer layer in the second embodiment and Comparative Example 2-4. [Figure 8] FIG. 10 is a diagram showing the relationship between the exchange coupling magnetic field and the magnetoresistance ratio in the second embodiment and Comparative Example 2-4. [Figure 9] FIG. 11 is a cross-sectional view of a variable resistance element of a magnetic memory device according to a third embodiment. [Figure 10] FIG. 10 is a diagram showing the cross-sectional structure and characteristics of the metal cap layer and the oxide cap layer in the third embodiment and Comparative Examples 5-7. [Figure 11] FIG. 10 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. [Figure 12] FIG. 11 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. [Figure 13] FIG. 13 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 OF THE INVENTION
[0007] Hereinafter, embodiments will be described with reference to the drawings. In the following description, components having the same function and configuration will be assigned the same reference numerals. Furthermore, the embodiments shown below are merely examples of devices and methods for embodying the technical ideas of the embodiments, and do not specify the materials, shapes, structures, arrangements, etc. of the components as described below.
[0008] 1. First embodiment First, a memory system including the magnetic memory device of the first embodiment will be described.
[0009] 1.1 Memory System An example of a memory system will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the configuration of a memory system MS including a magnetic memory device according to a first embodiment.
[0010] 1, the memory system MS includes a magnetic storage device 1 and a memory controller 2. The magnetic storage device 1 operates under the control of the memory controller 2. In response to a request (or command) from an external host device, the memory controller 2 can instruct the magnetic storage device 1 to perform a read operation, a write operation, etc.
[0011] The magnetic memory device 1 is a type of resistance change memory. The magnetic memory device 1 is a memory device that uses MTJ (Magnetic Tunnel Junction) elements as memory cells. The MTJ elements utilize the magnetoresistance effect caused by a magnetic tunnel junction. The MTJ elements are also called magnetoresistance effect elements.
[0012] The magnetic memory 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.
[0013] 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. FIG. 1 shows a set of memory cells MC, word lines WL, and bit lines BL. The memory cells MC can store data in a non-volatile manner. The memory cells MC are connected between one word line WL and one bit line BL, and correspond to a set of a row and a column. 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 specified by selecting one row and one or more columns.
[0014] The input / output circuit 12 is connected to the memory controller 2 and controls communication between the magnetic storage device 1 and the memory controller 2. The input / output circuit 12 transfers the control signal CNT and command CMD received from the memory 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 memory 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 memory 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 memory controller 2.
[0015] The control circuit 13 controls the overall operation of the magnetic memory device 1. For example, the control circuit 13 executes read operations, write operations, etc. based on the control indicated by the control signal CNT and the command CMD. For example, in a write operation, the control circuit 13 supplies a voltage used for writing data to the write circuit 16. In addition, in a read operation, the control circuit 13 supplies a voltage used for reading data to the read circuit 17.
[0016] 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).
[0017] 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 lines BL are electrically connected to, for example, a driver circuit (not shown).
[0018] The write circuit 16 supplies a voltage used for writing data to the column selection 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 to the memory cell MC.
[0019] The read circuit 17 includes a sense amplifier. Based on the control of the control circuit 13, the read circuit 17 supplies a voltage used for reading data to the column selection circuit 15. Then, the sense amplifier determines the data stored in the memory cell MC based on the voltage or current of the selected bit line BL. Furthermore, the read circuit 17 transfers data DAT (read data) corresponding to the determination result to the input / output circuit 12.
[0020] 1.2 Magnetic Storage Devices 1.2.1 Memory cell array circuit configuration An example of the circuit configuration of the memory cell array 11 included in the magnetic memory device 1 will be described with reference to Fig. 2. Fig. 2 is a circuit diagram showing the circuit configuration of the memory cell array 11 included in the magnetic memory device 1 of the first embodiment. Fig. 2 shows WL0 and WL1 extracted from the multiple word lines WL and BL0 and BL1 extracted from the multiple bit lines BL.
[0021] 2, one memory cell MC is connected between WL0 and BL0, between WL0 and BL1, between WL1 and BL0, and between WL1 and BL1, respectively. The memory cells MC are arranged in the memory cell array 11, for example, in a matrix.
[0022] Each memory cell MC includes a variable resistance element VR and a switching element SE. The variable resistance element VR and the switching element SE are connected in series between the associated bit line BL and word line WL. For example, one end of the variable resistance element VR is connected to the bit line BL. The other end of the variable resistance element VR is connected to one end of the switching element SE. The other end of the switching element SE is connected to the word line WL. Note that the connection relationship between the variable resistance element VR and the switching element SE between the bit line BL and the word line WL may be reversed. That is, one end of the variable resistance element VR is connected to the word line WL, and the other end of the variable resistance element VR is connected to one end of the switching element SE. The other end of the switching element SE may be connected to the bit line BL.
[0023] The variable resistance element VR corresponds to an MTJ element. The variable resistance element VR can store data nonvolatilely based on its resistance value. For example, a memory cell MC including a variable resistance element VR in a high resistance state stores data "1." A memory cell MC including a variable resistance element VR in a low resistance state stores data "0." The assignment of data associated with the resistance value of the variable resistance element VR may be other settings. The resistance state of the variable resistance element VR can change depending on the current flowing through the variable resistance element VR.
[0024] 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 certain 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 is equal to or higher 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. When the switching element SE is in the off state, current flow is suppressed between the word line WL and the bit line BL connected to the memory cell MC. The switching element SE in the on state functions as a conductor with a low resistance. 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 to pass current depending on the magnitude of the voltage applied to the memory cell MC, regardless of the direction of current flow. Note that other elements, such as a transistor, may also be used as the switching element SE.
[0025] 1.2.2 Memory cell array structure An example of the structure of the memory cell array 11 included in the magnetic memory device 1 will be described below. In the following description, an XYZ Cartesian coordinate system is used. The X direction corresponds to the extension direction of the bit lines BL. The Y direction corresponds to the extension direction of the word lines WL. The Z direction corresponds to the vertical direction relative to the surface of the semiconductor substrate used to form the magnetic memory device 1. The term "bottom" and its derivatives and related terms refer to a position with a smaller coordinate on the Z axis. The term "top" and its derivatives and related terms refer to a position with a larger coordinate on the Z axis. Hatching is added appropriately to the perspective views. The hatching added to the perspective views does not necessarily relate to the materials or characteristics of the components to which the hatching is added. In the perspective views and cross-sectional views, illustrations of components such as interlayer insulating films are omitted.
[0026] An example of the three-dimensional structure of the memory cell array 11 included in the magnetic memory device 1 will be described with reference to Fig. 3. Fig. 3 is a perspective view showing the structure of the memory cell array 11 included in the magnetic memory device 1 of the first embodiment.
[0027] As shown in FIG. 3, the memory cell array 11 includes a plurality of conductor layers 20, a plurality of conductor layers 21, and a plurality of memory cells MC.
[0028] Each of the plurality of conductive layers 20 has a portion extending in the X direction. The plurality of conductive layers 20 are arranged side by side in the Y direction and spaced apart from one another. Each conductive layer 20 is used as a bit line BL.
[0029] Each of the plurality of conductive layers 21 has a portion extending in the Y direction. The plurality of conductive layers 21 are arranged side by side in the X direction and spaced apart from one another. Each conductive layer 21 is used as a word line WL.
[0030] A wiring layer including a plurality of conductor layers 21 is provided above a wiring layer including a plurality of conductor layers 20. One memory cell MC is provided at each intersection of the plurality of conductor layers 20 and the plurality of conductor layers 21. In other words, each memory cell MC is provided between an 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 on the conductor layer 20. A switching element SE is provided on the variable resistance element VR. A conductor layer 21 is provided on the switching element SE.
[0031] Although the case where the variable resistance element VR is provided below the switching element SE has been exemplified, depending on the circuit configuration of the memory cell array 11, the variable resistance element VR may be provided above the switching element SE.
[0032] 1.2.3 Cross-sectional structure of a variable resistance element Next, the cross-sectional structure of the variable resistance element VR included in the memory cell MC will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view of the variable resistance element VR included in the memory cell MC of the magnetic memory device 1 of the first embodiment.
[0033] 4, the variable resistance element VR includes, for example, a non-magnetic layer 30, a 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. Note that in FIG. 4 and the following figures, the magnetization directions of the magnetic layers are indicated by arrows. The double-headed arrows indicate that the magnetization direction is variable.
[0034] Non-magnetic layer 30, ferromagnetic layer 31, non-magnetic layer 32, ferromagnetic layer 33, non-magnetic layer 34, ferromagnetic layer 35, non-magnetic layer 36, and non-magnetic layer 37 are stacked in this order from the conductor layer 20 (bit line BL) side toward the conductor layer 21 (word line WL) side (in the Z direction).
[0035] 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.
[0036] 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.
[0037] 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. The nonmagnetic layer 30 has 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.
[0038] The first layer 30a has an amorphous structure and contains hafnium (Hf) or hafnium boron (HfB).
[0039] The second layer 30b has a body-centered cubic (BCC) crystal structure with a
[0110] plane perpendicular to the stacking direction of the
[0100] layer structure. By using such a second layer 30b, the ferromagnetic layer 31 can be favorably oriented in a face-centered cubic (FCC)
[0111] plane or a hexagonal close packed (HCP)
[0001] plane. This improves the perpendicular magnetic anisotropy of the ferromagnetic layer 31. The second layer 30b may contain at least one element selected from molybdenum (Mo), tungsten (W), and tantalum (Ta). That is, the second layer 30b may be a molybdenum (Mo) layer, a tungsten (W) layer, or a tantalum (Ta) layer. The second layer 30b may also be an alloy layer of two or more elements selected from molybdenum (Mo), tungsten (W), and tantalum (Ta).
[0040] Although the nonmagnetic layer 30 is shown as two layers in the example shown in FIG. 4, it may be a laminate of three or more layers.
[0041] The ferromagnetic layer 31 is a ferromagnetic conductor. The ferromagnetic layer 31 has an easy axis of magnetization perpendicular to the film surface. In the example shown in FIG. 4, the magnetization direction of the ferromagnetic layer 31 faces the ferromagnetic layer 33. The magnitude of the magnetic field required to reverse the magnetization direction of the ferromagnetic layer 31 is, for example, larger than that of the ferromagnetic layer 33. The leakage magnetic field from the ferromagnetic layer 31 reduces the influence 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 cancelling layer (SCL).
[0042] The ferromagnetic layer 31 may contain, for example, at least one element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). The ferromagnetic layer 31 may also 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 31 may contain cobalt iron boron (CoFeB). The ferromagnetic layer 31 may also contain at least one binary compound selected from the group consisting of iron boride (FeB), cobalt platinum (CoPt), cobalt nickel (CoNi), and cobalt palladium (CoPd).
[0043] The nonmagnetic layer 32 is a nonmagnetic conductor. The nonmagnetic layer 32 is used as a spacer layer SP (Spacer Layer) between the ferromagnetic layer 31 and the ferromagnetic layer 33, and is antiferromagnetically coupled to the ferromagnetic layer 31. This fixes the magnetization direction of the ferromagnetic layer 31 in a direction antiparallel to the magnetization direction of the ferromagnetic layer 33. Such a coupled structure of the ferromagnetic layer 31, the nonmagnetic layer 32, and the ferromagnetic layer 33 is called an SAF (Synthetic Anti-Ferromagnetic) structure. The nonmagnetic layer 32 contains, for example, at least one element selected from the group consisting of ruthenium (Ru), osmium (Os), iridium (Ir), vanadium (V), and chromium (Cr).
[0044] The ferromagnetic layer 33 is a ferromagnetic conductor. The ferromagnetic layer 33 has an easy axis of magnetization 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. In the example shown in FIG. 4, the magnetization direction of the ferromagnetic layer 33 is fixed to the ferromagnetic layer 31 side. This allows the ferromagnetic layer 33 to be used as a reference layer RL of the MTJ element. The reference layer RL is also called a "pinned layer" or a "fixed layer."
[0045] The ferromagnetic layer 33 includes ferromagnetic layers 33a and 33b. The ferromagnetic layer 33a is provided above the nonmagnetic layer 32. The ferromagnetic layer 33b is provided above the ferromagnetic layer 33a. The ferromagnetic layer 33a functions as a main reference layer MRL. The ferromagnetic layer 33b functions as an interface layer IL between the nonmagnetic layer 34 and the main reference layer MRL.
[0046] The ferromagnetic layer 33a may contain, for example, at least one element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). The ferromagnetic layer 33a may also 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 33a may contain cobalt-iron-boron (CoFeB). The ferromagnetic layer 33a may also contain at least one binary compound selected from the group consisting of iron boride (FeB), cobalt-platinum (CoPt), cobalt-nickel (CoNi), and cobalt-palladium (CoPd). The ferromagnetic layer 33b may include, for example, cobalt iron boron (CoFeB) or iron boride (FeB).
[0047] The nonmagnetic layer 34 is a nonmagnetic insulator. The nonmagnetic layer 34 forms a magnetic tunnel junction together with the ferromagnetic layers 33 and 35. That is, the nonmagnetic layer 34 functions as a tunnel barrier layer (TB) of the MTJ element. The nonmagnetic layer 34 also functions as a seed material in 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 nonmagnetic layer 34 includes, for example, an oxide of at least one element or compound selected from the group consisting of magnesium (Mg), aluminum (Al), zinc (Zn), titanium (Ti), and LSM (Lanthanum-Strontium-Manganese).
[0048] The ferromagnetic layer 35 is a ferromagnetic conductor. The ferromagnetic layer 35 has an easy axis of magnetization perpendicular to the film surface. The magnetization direction of the ferromagnetic layer 35 is directed toward either the ferromagnetic layer 33 or the non-magnetic layer 36. The magnetization direction of the ferromagnetic layer 35 is configured to be more easily reversible than that of the ferromagnetic layer 33. This allows the ferromagnetic layer 35 to be used as a storage layer SL of the MTJ element. The storage layer SL is also called a "free layer."
[0049] The ferromagnetic layer 35 includes, for example, at least one element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). The ferromagnetic layer 35 may also include, 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 include cobalt iron boron (CoFeB) or iron boride (FeB).
[0050] The nonmagnetic layer 36 is a nonmagnetic oxide. The nonmagnetic layer 36 is used as an oxide cap layer OxCP for the ferromagnetic layer 35 (memory layer SL). The nonmagnetic layer 36 (oxide cap layer OxCP) is in contact with the ferromagnetic layer 35 (memory layer SL). The nonmagnetic layer 36 can improve the perpendicular magnetic anisotropy of the ferromagnetic layer 35. The nonmagnetic layer 36 contains an oxide, such as magnesium oxide (MgO), aluminum oxide (Al2O3), or a rare earth oxide. The nonmagnetic layer 36 may also be a mixture of these oxides. That is, the nonmagnetic layer 36 is not limited to a binary compound consisting of two elements, but may also contain a ternary compound consisting of three elements, such as magnesium aluminum oxide (MgAl2O4). The nonmagnetic layer 36 also contains at least one element selected from the group consisting of iridium (Ir), platinum (Pt), and ruthenium (Ru).
[0051] The nonmagnetic layer 37 is a nonmagnetic conductor. The nonmagnetic layer 37 is used as a metal cap layer MCP for the ferromagnetic layer 35 (memory layer SL). The nonmagnetic layer 37 includes nonmagnetic layers 37a, 37b, and 37c. The nonmagnetic layer 37a is provided above the nonmagnetic layer 36. The nonmagnetic layer 37b is provided above the nonmagnetic layer 37a. The nonmagnetic layer 37c is provided above the nonmagnetic layer 37b. In other words, 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. Hereinafter, the nonmagnetic layers 37a, 37b, and 37c will also be referred to as a first metal cap layer MCP1, a second metal cap layer MCP2, and a third metal cap layer MCP3, respectively.
[0052] The non-magnetic layers 37a (first metal cap layer MCP1) and 37b (second metal cap layer MCP2) can have functions such as improving the characteristics of the MTJ element, functioning as a hard mask, or functioning as an electrode. The non-magnetic layer 37a contains, for example, tantalum (Ta). The non-magnetic layer 37b contains, for example, a compound (HfB) of hafnium (Hf) and boron (B), or hafnium (Hf). When the non-magnetic layer 37b contains a hard material, i.e., a material with high hardness, such as the hafnium-boron compound (HfB) or hafnium (Hf), it is possible to reduce the defect rate in the MTJ element.
[0053] The nonmagnetic layer 37c (third metal cap layer MCP3) can be used as an electrode that improves electrical connectivity between the variable resistance element VR and an upper element (e.g., switching element SE) or a conductor layer (e.g., bit line BL) 20. The nonmagnetic layer 37c contains at least one element selected from the group consisting of ruthenium (Ru), platinum (Pt), tungsten (W), and tantalum (Ta).
[0054] The variable resistance element VR described above functions as a perpendicular magnetization MTJ element utilizing the TMR (Tunneling Magnetoresistance) effect. The variable resistance 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 (memory layer SL). Specifically, the variable resistance element VR is in a high resistance state when the magnetization directions of the reference layer RL and the memory layer SL are antiparallel (AP (Antiparallel) state), and in a low resistance state when the magnetization directions of the reference layer RL and the memory layer SL are parallel (P (Parallel) state).
[0055] The magnetic memory 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 changing the magnetization direction of the ferromagnetic layer 35 (memory layer SL). Specifically, the magnetic memory device 1 injects spin torque into the memory layer SL and the reference layer RL by passing a write current through the variable resistance element VR, thereby controlling the magnetization direction of the memory layer SL. This type of write method is called a "spin injection write method."
[0056] In this example, the variable resistance element VR is in the AP state when a write current is passed in the direction from the ferromagnetic layer 33 to the ferromagnetic layer 35, and is in the P state when a write current is passed in the direction from the ferromagnetic layer 35 to the ferromagnetic layer 33. 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 is passed 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 when a current of a magnitude sufficient to reverse the magnetization direction of the ferromagnetic layer 35 is passed through the variable resistance element VR.
[0057] The variable resistance element VR may include other layers, and each ferromagnetic layer and each non-magnetic layer may be made up of a plurality of layers.
[0058] 1.2.4 Comparison of characteristics based on differences in metal cap layers Below, 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, using Comparative Example 1 for the first embodiment. Fig. 5 is a diagram showing the cross-sectional structure and characteristics of the metal cap layer in the first embodiment and Comparative Example 1. The cross-sectional structure shown in Fig. 5 shows an excerpt of the ferromagnetic layer 35 (memory layer SL), nonmagnetic layer 36 (cap layer OxCP), and nonmagnetic layer 37 (metal cap layer MCP) of the layer structure corresponding to the variable resistance element VR formed on a silicon substrate.
[0059] 5, cobalt iron boron (CoFeB) is used for the ferromagnetic layer 35 (memory layer SL) in both the first embodiment and comparative example 1. An oxide is used for the nonmagnetic layer 36 (cap layer OxCP) in both the first embodiment and comparative example 1. In the first embodiment and comparative example 1, the same material is used for the other layers except for the nonmagnetic layer 37 (metal cap layer MCP).
[0060] The metal cap layers MCP of the first embodiment and Comparative Example 1 have different structures. In the first embodiment, a metal cap layer MCP1 containing tantalum (Ta), a metal cap layer MCP2 containing hafnium boron compound (HfB), and a metal cap layer MCP3 containing ruthenium (Ru) are provided in this order above the cap layer OxCP. In Comparative Example 1, a metal cap layer MCP containing tantalum (Ta) and a metal cap layer MCP containing ruthenium (Ru) are provided in this order above the cap layer OxCP.
[0061] The etching rate of the metal cap layer MCP2 containing a hafnium boron compound (HfB) in the first embodiment is about 2.5 (Å / sec). The etching rate of the metal cap layer MCP containing ruthenium (Ru) in the comparative example 1 is about 4.3 (Å / sec).
[0062] The SFR (Shunt Fail Rate) of the memory cells MC of the magnetic memory device 1 of the first embodiment is approximately 3.4 percent. In contrast, the SFR of the memory cells of Comparative Example 1 is approximately 79.9 percent. The SFR represents the rate of occurrence of defects caused by short circuits between the memory layer SL and the reference layer RL in the MTJ element.
[0063] From the above, it can be seen that in the first embodiment, which has a metal cap layer MCP2 containing a hard material such as hafnium boron compound (HfB), the SFR in the memory cell MC can be reduced compared to comparative example 1, which does not have a metal cap layer of hafnium boron compound (HfB).
[0064] 1.3 Effects of the First Embodiment According to the magnetic memory device 1 of the first embodiment, the rate of occurrence of defects in memory cells can be reduced, and the performance of memory cells can be improved.
[0065] The effects of the first embodiment will be described in detail below.
[0066] One way to increase the storage capacity of a magnetic memory device is to miniaturize the memory cells MC and narrow the pitch of the memory cell MC to arrange them at a higher density. As the memory cells MC become smaller and the pitch becomes narrower, the rate of defects in the memory cells MC in the magnetic memory device may increase. Therefore, there is a demand for a reduction in the SFR in the magnetic memory device.
[0067] 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 memory layer SL. This reduces the SFR in the memory cell MC. Therefore, the defect rate of the memory cell MC in the magnetic storage device can be reduced, and the performance of the memory cell can be improved.
[0068] 2. Second embodiment Next, a magnetic memory device according to a second embodiment will be described. The configuration of the memory 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. In the following embodiments, these configurations are also the same as those in the first embodiment, so descriptions will be omitted. In the second embodiment, a variable resistance element VR different from that in the first embodiment will be described. In the variable resistance element VR in the second embodiment, the nonmagnetic layer 30 (buffer layer BL) contains silicon (Si), and the nonmagnetic layer 37 (metal cap layer MCP) contains molybdenum (Mo).
[0069] 2.1 Cross-sectional structure of a variable resistance element The cross-sectional structure of the variable resistance element VR of the second embodiment will be described below with reference to Fig. 6. Fig. 6 is a cross-sectional view of the variable resistance element VR included in the memory cell MC of the magnetic memory device 1 of the second embodiment.
[0070] 6, the variable resistance element VR includes, for example, a non-magnetic layer 30, a 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. Of these layers, descriptions of layers that are the same as those in the first embodiment will be omitted, and the following will mainly describe layers that have configurations and materials different from those in the first embodiment.
[0071] 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. That is, 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.
[0072] The first layer 30a has an amorphous structure and contains hafnium (Hf) or hafnium boron (HfB).
[0073] The second layer 30b has a body-centered cubic (BCC) crystal structure with a
[0110] plane perpendicular to the stacking direction of the
[0100] layer structure. By using such a second layer 30b, the ferromagnetic layer 31 can be favorably oriented in a face-centered cubic (FCC)
[0111] plane or a hexagonal close packed (HCP)
[0001] plane. This improves the perpendicular magnetic anisotropy of the ferromagnetic layer 31. The second layer 30b may contain at least one element selected from molybdenum (Mo), tungsten (W), and tantalum (Ta). That is, the second layer 30b may be a molybdenum (Mo) layer, a tungsten (W) layer, or a tantalum (Ta) layer. The second layer 30b may also be an alloy layer of two or more elements selected from molybdenum (Mo), tungsten (W), and tantalum (Ta).
[0074] 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, it is possible to suppress element diffusion due to heat treatment, and it is possible to obtain a variable resistance element VR with excellent heat resistance. That is, it is possible to suppress characteristic degradation due to heat treatment, and it is possible to increase the magnetoresistance ratio (MR ratio) of the MTJ element of the variable resistance element VR. The MR ratio is calculated by dividing the amount of change in electrical resistance when the MTJ element changes from the P state to the AP state by the electrical resistance in the P state. Furthermore, by providing the third layer 30c, it is possible to improve the perpendicular magnetic anisotropy of the ferromagnetic layer 31.
[0075] Although the nonmagnetic layer 30 is shown as three layers in the example shown in FIG. 6, it may be a laminate of two layers or four or more layers.
[0076] The non-magnetic layer 36 is a non-magnetic oxide. The non-magnetic layer 36 is used as an oxide cap layer OxCP for the ferromagnetic layer 35 (storage layer SL). The non-magnetic layer 36 is in contact with the ferromagnetic layer 35. 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 gadolinium oxide (GdOx), aluminum oxide (AL2O3), or a rare earth oxide. The non-magnetic layer 36 may also be a mixture of these oxides.
[0077] The nonmagnetic layer 37 is a nonmagnetic conductor. The nonmagnetic layer 37 is used as a metal cap layer MCP for the ferromagnetic layer 35 (memory layer SL). The nonmagnetic layer 37 can have, for example, a function to improve the characteristics of the MTJ element, a function as a hard mask, or a function as an electrode. The nonmagnetic layer 37 contains, for example, molybdenum (Mo).
[0078] When the nonmagnetic layer 30 (buffer layer BL) contains silicon (Si) or a silicon compound and the nonmagnetic layer 37 (metal cap layer MCP) contains molybdenum (Mo), the magnetoresistance ratio (MR ratio) of the MTJ element becomes even larger.
[0079] 2.2 Comparison of characteristics based on differences in metal cap layer and buffer layer Below, we will explain the changes in the characteristics of the variable resistance element VR (MTJ element) based on differences in the metal cap layer and buffer layer using Comparative Example 2-4 for the second embodiment. Figure 7 is a diagram showing the cross-sectional structures of the metal cap layer and buffer layer in the second embodiment and Comparative Example 2-4. The cross-sectional structure shown in Figure 7 shows the nonmagnetic layer 30 (buffer layer BL), ferromagnetic layer 35 (memory layer SL), nonmagnetic layer 36 (cap layer OxCP), and nonmagnetic layer 37 (metal cap layer MCP) of the layer structure corresponding to the variable resistance element VR.
[0080] 7, the ferromagnetic layer 35 (memory layer SL) of the second embodiment and comparative example 2-4 is made of cobalt iron boron (CoFeB). The nonmagnetic layer 36 (cap layer OxCP) of the second embodiment and comparative example 2-4 is made of gadolinium oxide (GdOx). In the second embodiment and comparative example 2-4, the layers other than the nonmagnetic layer 30 (buffer layer BL) and nonmagnetic layer 37 (metal cap layer MCP) are made of the same material.
[0081] 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 shift cancellation layer SCL.
[0082] In Comparative Example 2, a metal cap layer MCP containing ruthenium (Ru) and a metal cap layer MCP containing tantalum (Ta) are provided in this order above the cap layer OxCP. Furthermore, the buffer layer BL provided below the shift cancellation layer SCL does not contain silicon (Si).
[0083] In Comparative Example 3, a metal cap layer MCP containing ruthenium (Ru) and a metal cap layer MCP containing tantalum (Ta) are provided in this order above the cap layer OxCP, as in Comparative Example 2. Furthermore, a buffer layer BL containing silicon (Si) is provided below the shift cancellation layer SCL.
[0084] In Comparative Example 4, a metal cap layer MCP containing molybdenum (Mo) is provided above the cap layer OxCP. Furthermore, the buffer layer BL provided below the shift cancellation layer SCL does not contain silicon (Si).
[0085] The magnetoresistance change rates in the second embodiment and comparative example 2-4 will be described below with reference to Fig. 8. Fig. 8 is a diagram showing the relationship between the exchange coupling magnetic field and the magnetoresistance change rate in the second embodiment and comparative example 2-4. In Fig. 8, 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 strength of the magnetic field that fixes the reference layer RL in the SAF structure consisting of the shift cancellation layer SCL and the reference layer RL.
[0086] In Comparative Example 2, the buffer layer BL does not contain silicon (Si) and the metal cap layer MCP does not contain molybdenum (Mo). As shown in FIG. 8, Comparative Example 2 has a weaker exchange coupling magnetic field and a smaller magnetoresistance ratio than the second embodiment and Comparative Example 3.
[0087] In Comparative Example 3, the buffer layer BL contains silicon (Si) and the metal cap layer MCP does not contain molybdenum (Mo). As shown in Fig. 8, Comparative Example 3 has a stronger exchange coupling magnetic field than Comparative Examples 2 and 4, and a weaker exchange coupling magnetic field and a smaller magnetoresistance ratio than the second embodiment.
[0088] In Comparative Example 4, the buffer layer BL does not contain silicon (Si) and the metal cap layer MCP contains molybdenum (Mo). As shown in FIG. 8, Comparative Example 4 has a weaker exchange coupling magnetic field and a smaller magnetoresistance ratio than the second embodiment and Comparative Example 3.
[0089] In the second embodiment, the buffer layer BL contains silicon (Si) and the metal cap layer MCP contains molybdenum (Mo). As shown in FIG. 8, the second embodiment has a stronger exchange coupling magnetic field and a larger magnetoresistance ratio than Comparative Example 2-4.
[0090] More specifically, in the second embodiment, by providing a buffer layer BL containing silicon (Si), it is possible to improve the heat resistance of the shift cancellation layer SCL and the reference layer RL that constitute the SAF structure. Furthermore, by providing a metal cap layer MCP containing molybdenum (Mo), it is possible to improve the heat resistance of the memory layer SL. As a result, in the variable resistance element VR of the second embodiment, it is possible to improve both the exchange coupling magnetic field and the magnetoresistance rate of change.
[0091] 2.3 Effects of the second embodiment According to the magnetic memory device 1 of the second embodiment, the performance of the memory cells can be improved.
[0092] The effects of the second embodiment will be described in detail below.
[0093] One way to increase the storage capacity of a magnetic memory device is to miniaturize the memory cells MC and narrow the pitch of the memory cells MC, thereby arranging the memory cells MC at a higher density. As the memory cells MC are miniaturized and the pitch is narrowed, the magnetoresistance change rate of the memory cells MC may decrease. Therefore, there is a demand for an increase in the magnetoresistance change rate of the memory cells MC.
[0094] In contrast, the configuration of the second embodiment includes a buffer layer BL containing silicon (Si) below the shift cancellation layer SCL, and a metal cap layer MCP containing molybdenum (Mo) above the memory layer SL. This allows the magnetoresistance change rate to be increased while maintaining the strength of the exchange coupling magnetic field. Therefore, the performance of the memory cell MC in the magnetic storage device can be improved.
[0095] 3. Third embodiment Next, a magnetic memory device according to a third embodiment will be described. In the third embodiment, a variable resistance element VR different from those of the first and second embodiments will be described. In the variable resistance element VR of the third embodiment, the non-magnetic layer 36 (cap layer OxCP) contains magnesium oxide (MgO), and the non-magnetic layer 37 (metal cap layer MCP) contains molybdenum (Mo).
[0096] 3.1 Cross-sectional structure of variable resistance element The cross-sectional structure of the variable resistance element VR of the third embodiment will be described below with reference to Fig. 9. Fig. 9 is a cross-sectional view of the variable resistance element VR included in the memory cell MC of the magnetic memory device 1 of the third embodiment.
[0097] 9, the variable resistance element VR includes, for example, a non-magnetic layer 30, a 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. Of these layers, descriptions of layers that are the same as those in the first embodiment will be omitted, and the following will mainly describe layers that have configurations and materials different from those in the first embodiment.
[0098] The nonmagnetic layer 36 is a nonmagnetic oxide. The nonmagnetic layer 36 is used as an oxide cap layer OxCP for the ferromagnetic layer 35 (memory 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 contains, for example, magnesium oxide (MgO).
[0099] The nonmagnetic layer 37 is a nonmagnetic conductor. The nonmagnetic layer 37 is used as a metal cap layer MCP for the ferromagnetic layer 35 (memory layer SL). The nonmagnetic layer 37 can have, for example, a function to improve the characteristics of the MTJ element, a function as a hard mask, or a function as an electrode. The nonmagnetic layer 37 contains, for example, molybdenum (Mo).
[0100] The non-magnetic layer 36 (cap layer OxCP) contains magnesium oxide (MgO) and the non-magnetic layer 37 (metal cap layer MCP) contains molybdenum (Mo), thereby increasing the anisotropic magnetic field of the memory layer SL in the MTJ element.
[0101] 3.2 Comparison of characteristics based on differences between metal cap layer and oxide cap layer Below, we will explain the changes in the characteristics of the variable resistance element VR (MTJ element) based on differences in the metal cap layer and oxide cap layer using comparative examples 5-7 for the third embodiment. Fig. 10 is a diagram showing the cross-sectional structures and characteristics of the metal cap layer and oxide cap layer in the third embodiment and comparative examples 5-7. The cross-sectional structure shown in Fig. 10 shows an excerpt of the ferromagnetic layer 35 (memory layer SL), nonmagnetic layer 36 (cap layer OxCP), and nonmagnetic layer 37 (metal cap layer MCP) of the layer structure corresponding to the variable resistance element VR.
[0102] 10, the ferromagnetic layer 35 (memory layer SL) of the third embodiment and comparative examples 5-7 is made of cobalt iron boron (CoFeB). In the third embodiment and comparative examples 5-7, the layers other than the nonmagnetic layer 36 (cap layer OxCP) and the nonmagnetic layer 37 (metal cap layer MCP) are made of the same material.
[0103] In the third embodiment, a cap layer OxCP containing magnesium oxide (MgO) is provided above the memory layer SL. Furthermore, a metal cap layer MCP containing molybdenum (Mo) is provided above the cap layer OxCP.
[0104] In Comparative Example 5, a cap layer OxCP containing gadolinium oxide (GdOx) is provided above the memory layer SL. Furthermore, a metal cap layer MCP containing ruthenium (Ru) and a metal cap layer MCP containing tantalum (Ta) are provided in this order above the cap layer OxCP.
[0105] In Comparative Example 6, a cap layer OxCP containing magnesium oxide (MgO) is provided above the memory layer SL. Furthermore, a metal cap layer MCP containing ruthenium (Ru) and a metal cap layer MCP containing tantalum (Ta) are provided in this order above the cap layer OxCP.
[0106] In Comparative Example 7, a cap layer OxCP containing gadolinium oxide (GdOx) is provided above the memory layer SL. Furthermore, a metal cap layer MCP containing molybdenum (Mo) is provided above the cap layer OxCP.
[0107] 10, the anisotropy magnetic field of the memory layer SL in the third embodiment is approximately 5.5 (kOe). The anisotropy magnetic fields of the memory layer SL in comparative examples 5, 6, and 7 are approximately 3.1 (kOe), 3.2 (kOe), and 2.2 (kOe), respectively. These anisotropy magnetic fields are values when the product of the saturation magnetic field of the memory layer SL and its film thickness (i.e., the thickness in the Z direction) is constant.
[0108] In both Comparative Examples 5 and 6, the metal cap layer MCP includes a layer containing ruthenium (Ru) and a layer containing tantalum (Ta), and the cap layer OxCP includes gadolinium oxide (GdOx) in Comparative Example 5, while the cap layer OxCP includes magnesium oxide (MgO) in Comparative Example 6. The anisotropy magnetic fields of the memory layers SL in Comparative Examples 5 and 6 with such configurations are almost the same and cannot be increased.
[0109] In the third embodiment, by providing a cap layer OxCP containing magnesium oxide (MgO) and a metal cap layer MCP containing molybdenum (Mo), the anisotropy magnetic field of the memory layer SL can be increased compared to Comparative Examples 5 to 7. Note that, as shown in Comparative Example 7, even if a metal cap layer MCP containing molybdenum (Mo) is provided, if a cap layer OxCP containing magnesium oxide (MgO) is not provided, the anisotropy magnetic field of the memory layer SL cannot be increased.
[0110] 3.3 Effects of the third embodiment According to the magnetic memory device 1 of the third embodiment, the performance of the memory cells can be improved.
[0111] The effects of the third embodiment will be described in detail below.
[0112] One way to increase the storage capacity of a magnetic memory device is to miniaturize the memory cells MC and narrow the pitch of the memory cells MC, thereby arranging the memory cells MC at a higher density. Such miniaturization and narrowing of the pitch of the memory cells MC may result in a decrease in the thermal stability of the memory cells MC. Therefore, there is a need to improve the thermal stability of the memory cells MC.
[0113] In contrast, in the configuration of the third embodiment, a cap layer OxCP containing magnesium oxide (MgO) is provided above the memory layer SL, and a metal cap layer MCP containing molybdenum (Mo) is provided above the cap layer OxCP. This increases the anisotropic magnetic field of the memory layer SL. As a result, the thermal stability of the memory cell can be improved, and the performance of the memory cell can be improved.
[0114] 4. Fourth embodiment Next, a magnetic memory device according to a fourth embodiment will be described. In the fourth embodiment, a variable resistance element VR having the configuration described in the first, second, and third embodiments will be described.
[0115] In the variable resistance element VR in the fourth embodiment, the non-magnetic layer 30 (buffer layer BL) contains silicon (Si), the non-magnetic layer 36 (cap layer OxCP) contains magnesium oxide (MgO), the non-magnetic layer 37a (metal cap layer MCP1) contains molybdenum (Mo), the non-magnetic layer 37b (metal cap layer MCP2) contains a hafnium boron compound (HfB) or hafnium (Hf), and the non-magnetic layer 37c (metal cap layer MCP3) contains ruthenium (Ru).
[0116] 4.1 Cross-sectional structure of variable resistance element The cross-sectional structure of the variable resistance element VR of the fourth embodiment will be described below with reference to Fig. 11. Fig. 11 is a cross-sectional view of the variable resistance element VR included in the memory cell MC of the magnetic memory device 1 of the fourth embodiment.
[0117] As shown in FIG. 11, the variable resistance element VR includes, for example, a non-magnetic layer 30, a 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, a non-magnetic layer 37a, a non-magnetic layer 37b, and a non-magnetic layer 37c.
[0118] Non-magnetic layer 30, ferromagnetic layer 31, non-magnetic layer 32, ferromagnetic layer 33, non-magnetic layer 34, ferromagnetic layer 35, non-magnetic layer 36, non-magnetic layer 37a, non-magnetic layer 37b, and non-magnetic layer 37c are stacked in this order from the conductor layer 20 (bit line BL) side toward the conductor layer 21 (word line WL) side (in the Z direction).
[0119] 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 37a is provided above the nonmagnetic layer 36. The nonmagnetic layer 37b is provided above the nonmagnetic layer 37a. The nonmagnetic layer 37c is provided above the nonmagnetic layer 37b. The conductive layer 21 is provided above the nonmagnetic layer 37c.
[0120] 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.
[0121] The non-magnetic layer 30 includes, for example, silicon (Si). The non-magnetic layer 36 (cap layer OxCP) includes, for example, magnesium oxide (MgO). The non-magnetic layer 37a (metal cap layer MCP1) includes, for example, molybdenum (Mo). The non-magnetic layer 37b (metal cap layer MCP2) includes, for example, hafnium boron compound (HfB) or hafnium (Hf). The non-magnetic layer 37c (metal cap layer MCP3) includes, for example, ruthenium (Ru).
[0122] The effects of the fourth embodiment are almost the same as those of the first, second, and third embodiments, and therefore will not be described here.
[0123] 5. Fifth embodiment Next, a magnetic memory 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.
[0124] 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 cap layer MCP1) contains molybdenum (Mo), the non-magnetic layer 37b (metal cap layer MCP2) contains a hafnium boron compound (HfB) or hafnium (Hf), and the non-magnetic layer 37c (metal cap layer MCP3) contains ruthenium (Ru).
[0125] 5.1 Cross-sectional structure of variable resistance element The cross-sectional structure of the variable resistance element VR of the fifth embodiment will be described below with reference to Fig. 12. Fig. 12 is a cross-sectional view of the variable resistance element VR included in the memory cell MC of the magnetic memory device 1 of the fifth embodiment.
[0126] The stacked structure of the fifth embodiment shown in Fig. 12 is the same as that of the fourth embodiment shown in Fig. 11. The nonmagnetic layer 36 (cap layer OxCP) contains, for example, gadolinium oxide (GdOx). The other structures and materials of the ferromagnetic layers and nonmagnetic layers are the same as those of the fourth embodiment.
[0127] The effects of the fifth embodiment are almost the same as those of the first and second embodiments, and therefore description thereof will be omitted.
[0128] 6. Sixth embodiment Next, a magnetic memory 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.
[0129] In the variable resistance element VR in the sixth embodiment, the nonmagnetic layer 30 (buffer layer BL) contains silicon (Si), the nonmagnetic layer 36 (cap layer OxCP) contains magnesium oxide (MgO), and the nonmagnetic layer 37 (metal cap layer MCP) contains molybdenum (Mo).
[0130] 6.1 Cross-sectional structure of a variable resistance element The cross-sectional structure of the variable resistance element VR of the sixth embodiment will be described below with reference to Fig. 13. Fig. 13 is a cross-sectional view of the variable resistance element VR included in the memory cell MC of the magnetic memory device 1 of the sixth embodiment.
[0131] As shown in FIG. 13, 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.
[0132] Non-magnetic layer 30, ferromagnetic layer 31, non-magnetic layer 32, ferromagnetic layer 33, non-magnetic layer 34, ferromagnetic layer 35, non-magnetic layer 36, and non-magnetic layer 37 are stacked in this order from the conductor layer 20 (bit line BL) side toward the conductor layer 21 (word line WL) side (in the Z direction).
[0133] 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.
[0134] 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.
[0135] The non-magnetic layer 30 includes, for example, silicon (Si). The non-magnetic layer 36 (cap layer OxCP) includes, for example, magnesium oxide (MgO). The non-magnetic layer 37 (metal cap layer MCP) includes, for example, molybdenum (Mo).
[0136] The effects of the sixth embodiment are almost the same as those of the second and third embodiments, and therefore description thereof will be omitted.
[0137] 7.Other In the embodiment, the magnetic storage device 1 has been described as an example of a magnetic device including an MTJ element (variable resistance element VR), but the present invention is not limited to this. The magnetic device may be other devices that require a magnetic element with perpendicular magnetic anisotropy, such as a sensor or a medium. The magnetic element may include at least a variable resistance element VR.
[0138] In this specification, "connected" refers to being electrically connected and does not exclude the presence of another element therebetween. Each of the nonmagnetic layers 32 and 37 may be called an "electrical conductive layer." The nonmagnetic layer 34 may be called an "oxide layer." The nonmagnetic layer 36 may be called 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) using a scanning transmission electron microscope (STEM).
[0139] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [Explanation of symbols]
[0140] 1...magnetic memory device, 2...memory controller, 11...memory cell array, 12...input / output circuit, 13...control circuit, 14...row selection circuit, 15...column selection circuit, 16...write circuit, 17...read circuit, 20...conductive layer, 21...conductive layer, 30...non-magnetic layer, 31...ferromagnetic layer, 32...non-magnetic layer, 33...ferromagnetic layer, 33a...ferromagnetic layer, 33b...ferromagnetic layer, 34...non-magnetic layer, 35...ferromagnetic layer, 36...non-magnetic layer, 37...non-magnetic layer, 37a...non-magnetic layer, 37b...non-magnetic layer, 37c...non-magnetic layer, MCP1...metal cap layer, MCP2...metal cap layer, MCP3...metal cap layer.
Claims
1. a first nonmagnetic layer containing silicon (Si); a first ferromagnetic layer provided above the first nonmagnetic layer; a second non-magnetic layer provided above the first ferromagnetic layer; a second ferromagnetic layer provided above the second nonmagnetic layer; a third non-magnetic layer provided above the second ferromagnetic layer; a third ferromagnetic layer provided above the third nonmagnetic layer; a fourth non-magnetic layer provided above the third ferromagnetic layer and containing magnesium (Mg) and oxygen (O); a fifth non-magnetic layer provided above the fourth non-magnetic layer and containing molybdenum (Mo); a sixth non-magnetic layer provided above the fifth non-magnetic layer and containing hafnium (Hf); a seventh non-magnetic layer provided above the sixth non-magnetic layer and containing ruthenium (Ru); A magnetic storage device comprising:
2. the fourth nonmagnetic layer contains at least one element selected from the group consisting of iridium (Ir), platinum (Pt), and ruthenium (Ru); 2. The magnetic storage device according to claim 1.
3. the first nonmagnetic layer contains a silicon (Si) compound; 2. The magnetic storage device according to claim 1.
4. the seventh nonmagnetic layer contains at least one element selected from the group consisting of platinum (Pt), tungsten (W), tantalum (Ta), and ruthenium (Ru); 2. The magnetic storage device according to claim 1.
5. the sixth nonmagnetic layer contains a compound of hafnium (Hf) and boron (B); 2. The magnetic storage device according to claim 1.
6. the fifth nonmagnetic layer contains a molybdenum (Mo) compound; 2. The magnetic storage device according to claim 1.
7. the third ferromagnetic layer and the fourth nonmagnetic layer are in contact with each other; 2. The magnetic storage device according to claim 1.
8. the second ferromagnetic layer contains at least one element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni); the third nonmagnetic layer contains an oxide of at least one element or compound selected from the group consisting of magnesium (Mg), aluminum (Al), zinc (Zn), titanium (Ti), and LSM (Lanthanum-strontium-manganese); the third ferromagnetic layer contains at least one element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni); 2. The magnetic storage device according to claim 1.
9. the second nonmagnetic layer is antiferromagnetically coupled to the first ferromagnetic layer, the magnetization direction of the first ferromagnetic layer is fixed in a direction antiparallel to the magnetization direction of the second ferromagnetic layer; 2. The magnetic storage device according to claim 1.
10. the first ferromagnetic layer contains at least one element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni); 2. The magnetic storage device according to claim 1.
11. the second nonmagnetic layer contains at least one element selected from the group consisting of ruthenium (Ru), osmium (Os), iridium (Ir), vanadium (V), and chromium (Cr); 2. The magnetic storage device according to claim 1.
12. each of the second ferromagnetic layer and the third ferromagnetic layer has an easy axis of magnetization in a 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 easily reversed compared to that of the second ferromagnetic layer.
2. The magnetic storage device according to claim 1.
13. 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; a memory cell provided between the first conductive layer and the second conductive layer; Furthermore, the memory cell includes the first ferromagnetic layer, the second ferromagnetic layer, the third ferromagnetic layer, the first non-magnetic layer, the second non-magnetic layer, the third non-magnetic layer, the fourth non-magnetic layer, the fifth non-magnetic layer, the sixth non-magnetic layer, and the seventh non-magnetic layer; 2. The magnetic storage device according to claim 1.
14. a first nonmagnetic layer containing silicon (Si); a first ferromagnetic layer provided above the first nonmagnetic layer; a second non-magnetic layer provided above the first ferromagnetic layer; a second ferromagnetic layer provided above the second nonmagnetic layer; a third non-magnetic layer provided above the second ferromagnetic layer; a third ferromagnetic layer provided above the third nonmagnetic layer; a fourth non-magnetic layer provided above the third ferromagnetic layer; a fifth non-magnetic layer provided above the fourth non-magnetic layer and containing molybdenum (Mo); a sixth non-magnetic layer provided above the fifth non-magnetic layer and containing hafnium (Hf); a seventh non-magnetic layer provided above the sixth non-magnetic layer and containing ruthenium (Ru); A magnetic storage device comprising:
15. the first nonmagnetic layer contains a silicon (Si) compound; 15. The magnetic storage device according to claim 14.
16. the sixth nonmagnetic layer contains a compound of hafnium (Hf) and boron (B); 15. The magnetic storage device according to claim 14.
17. the fifth nonmagnetic layer contains a molybdenum (Mo) compound; 15. The magnetic storage device according to claim 14.
18. a first nonmagnetic layer containing silicon (Si); a first ferromagnetic layer provided above the first nonmagnetic layer; a second non-magnetic layer provided above the first ferromagnetic layer; a second ferromagnetic layer provided above the second nonmagnetic layer; a third non-magnetic layer provided above the second ferromagnetic layer; a third ferromagnetic layer provided above the third nonmagnetic layer; a fourth non-magnetic layer provided above the third ferromagnetic layer and containing magnesium (Mg) and oxygen (O); a fifth non-magnetic layer provided above the fourth non-magnetic layer and containing molybdenum (Mo); A magnetic storage device comprising:
19. the first nonmagnetic layer contains a silicon (Si) compound; 20. The magnetic storage device according to claim 18.
20. the fifth nonmagnetic layer contains a molybdenum (Mo) compound; 20. The magnetic storage device according to claim 18.
Citation Information
Patent Citations
Electronic device and method for fabricating the same
US20150092481A1