TW202404105A - magnetic memory device - Google Patents

Abstract

In general, according to one embodiment, a magnetic memory device includes a magnetoresistive effect element. The magnetoresistive effect element includes first to second ferromagnetic layer, a layer stack, and first to third non-magnetic layer. The layer stack is arranged on a side opposite to the first ferromagnetic layer with respect to the second ferromagnetic layer. The third non-magnetic layer is arranged on a side opposite to the second non-magnetic layer with respect to the layer stack and contains a metallic oxide. The layer stack includes a fourth non-magnetic layer being in contact with the third non-magnetic layer and containing platinum (Pt).

Description

magnetic memory device

An embodiment of the present invention relates to a magnetic memory device.

Magnetic memory devices (MRAM: Magnetoresistive Random Access Memory) using magnetoresistive effect elements as memory elements are known.

The problem to be solved by the present invention is to provide a magnetic memory device that improves the resistance to external magnetic fields.

The magnetic memory device according to the embodiment includes a magnetoresistive effect element. The magnetoresistive effect element includes a first ferromagnetic layer, a second ferromagnetic layer, a laminated body, a first nonmagnetic layer, a second nonmagnetic layer, and a third nonmagnetic layer. The laminated body is provided on the side opposite to the first ferromagnetic layer with respect to the second ferromagnetic layer. The first nonmagnetic layer is provided between the first ferromagnetic layer and the second ferromagnetic layer. The second nonmagnetic layer is provided between the second ferromagnetic layer and the laminate. The third nonmagnetic layer is provided on the opposite side of the laminate to the second nonmagnetic layer and contains a metal oxide. The laminated body includes a fourth nonmagnetic layer that is in contact with the third nonmagnetic layer and includes platinum (Pt).

Hereinafter, embodiments will be described with reference to the drawings. In the description, components having substantially the same function and configuration are given the same symbols. In addition, the embodiment shown below is an illustration of a technical thinker. The embodiment does not specify the materials, shapes, structures, arrangements, etc. of the constituent parts. Various changes can be added to the embodiment.

[1] First embodiment The magnetic memory device according to the first embodiment will be described. The magnetic memory device of the first embodiment includes, for example, a perpendicular magnetization method using an element (MTJ element) having a magnetoresistance effect through a magnetic tunnel junction (MTJ) as a variable resistance element. Realized magnetic memory device. MTJ elements are also sometimes called magnetoresistance effect elements. In the embodiments described below including this embodiment, description will be made using a case where an MTJ element is used as the magnetoresistive effect element. In addition, for convenience of explanation, the magnetoresistance effect element MTJ will be described and explained.

[1-1]Composition First, the structure of the magnetic memory device according to the first embodiment will be described.

[1-1-1]Magnetic memory device FIG. 1 is a block diagram showing the structure of the magnetic memory device according to the first embodiment. As shown in FIG. 1 , the magnetic memory device 1 includes a memory cell array 10 , a column selection circuit 11 , a row selection circuit 12 , a decoding circuit 13 , a writing circuit 14 , a reading circuit 15 , a voltage generating circuit 16 , and an input/output circuit 17 , and control circuit 18.

The memory cell array 10 includes a plurality of memory cells MC each corresponding to a row and a column group. Specifically, the memory cells MC located in the same column are connected to the same word line WL, and the memory cells MC located in the same row are connected to the same bit line BL.

The column selection circuit 11 is connected to the memory cell array 10 via the word line WL. The column selection circuit 11 is supplied with the decoding result (column address) of the address ADD from the decoding circuit 13 . The column selection circuit 11 sets the word line WL corresponding to the column of the decoding result based on the address ADD to a selected state. Hereinafter, the word line WL set to the selected state is referred to as the selected word line WL. In addition, word lines WL other than the selected word lines WL are called non-selected word lines WL.

The row selection circuit 12 is connected to the memory cell array 10 via the bit line BL. The row selection circuit 12 is supplied with the decoding result (row address) of the address ADD from the decoding circuit 13 . The row selection circuit 12 sets the bit line BL corresponding to the row of the decoding result based on the address ADD to the selected state. Hereinafter, the bit line BL set to the selected state is referred to as the selected bit line BL. In addition, the bit lines BL other than the selected bit lines BL are called non-selected bit lines BL.

The decoding circuit 13 decodes the address ADD from the input/output circuit 17 . The decoding circuit 13 supplies the decoding result of the address ADD to the column selection circuit 11 and the row selection circuit 12 . The address ADD includes the selected row address and column address.

The writing circuit 14 writes data into the memory cell MC. The write circuit 14 includes, for example, a write driver (not shown).

The read circuit 15 reads data from the memory cell MC. The readout circuit 15 includes, for example, a sense amplifier (not shown).

The voltage generating circuit 16 uses the power supply voltage provided from the outside (not shown) of the magnetic memory device 1 to generate voltages for various operations of the memory cell array 10 . For example, the voltage generation circuit 16 generates various voltages required for writing operations and outputs them to the writing circuit 14 . For example, the voltage generation circuit 16 generates various voltages required for the reading operation and outputs the voltages to the reading circuit 15 .

The input-output circuit 17 transmits the external address ADD from the magnetic memory device 1 to the decoding circuit 13 . The input/output circuit 17 transmits the command CMD from the outside of the magnetic memory device 1 to the control circuit 18 . The input/output circuit 17 sends and receives various control signals CNT between the outside of the magnetic memory device 1 and the control circuit 18 . The input/output circuit 17 transmits the data DAT from the outside of the magnetic memory device 1 to the writing circuit 14 , and outputs the data DAT transmitted from the read circuit 15 to the outside of the magnetic memory device 1 .

The control circuit 18 controls the column selection circuit 11, the row selection circuit 12, the decoding circuit 13, the writing circuit 14, the reading circuit 15, the voltage generating circuit 16, and the input and output in the magnetic memory device 1 based on the control signal CNT and the command CMD. Action of circuit 17.

[1-1-2]Memory cell array Next, the structure of the memory cell array of the magnetic memory device according to the first embodiment will be described using FIG. 2 . FIG. 2 is a circuit diagram showing the structure of the memory cell array of the magnetic memory device according to the first embodiment. In FIG. 2 , the word lines WL are classified and displayed by a suffix including two lowercase letters (“u” and “d”) and an index (“＜＞”).

As shown in Figure 2, memory cells MC (MCu and MCd) are arranged in a matrix in the memory cell array 10, and are connected to a plurality of bit lines BL (BL<0>, BL<1>,..., BL<N>). 1, and a plurality of word lines WLd (WLd＜0＞, WLd＜1＞,…, WLd＜M＞) and WLu (WLu＜0＞, WLu＜1＞,…, WLu＜M＞) A corresponding relationship is established between groups of 1 (M and N are arbitrary integers). That is, memory cell MCd<i, j> (0≦i≦M, 0≦j≦N) is connected between word line WLd<i> and bit line BL<j>, memory cell MCu<i, j> is connected between word line WLu<i> and bit line BL<j>.

In addition, the "d" and "u" in the suffixes are used to facilitate the identification of the memory cells disposed below (for example, for the bit line BL) and the memory cells disposed above among the plurality of memory cells MC, respectively. Examples of the three-dimensional structure of the memory cell array 10 will be described later.

The memory cell MC<i,j> includes a series-connected switching element SELd<i,j> and a magnetoresistive effect element MTJd<i,j>. The memory cell MCu<i,j> includes a switching element SELu<i,j> and a magnetoresistive effect element MTJu<i,j> connected in series.

The switching element SEL has a function as a switch that controls the supply of current to the magnetoresistive effect element MTJ when writing and reading data to the corresponding magnetoresistive effect element MTJ. More specifically, for example, when the voltage applied to the memory cell MC is lower than the threshold voltage Vth, the switching element SEL in a certain memory cell MC acts as an insulator with a large resistance value and cuts off the current (turns into an off state). ), when the voltage is higher than the threshold voltage Vth, as a conductor with a small resistance value, current flows (becomes in a conductive state). That is, the switching element SEL has a function that is not limited to the direction of the flowing current and can switch the flow or interruption of the current in response to the magnitude of the voltage applied to the memory cell MC.

The switching element SEL may be, for example, a 2-terminal type switching element. The switching element SEL may be, for example, a 2-terminal type switching element. When the voltage applied between the two terminals does not reach the critical value, the switching element is in a "high resistance" state, such as an electrically non-conducting state. When the voltage applied between the two terminals is above a threshold value, the switching element changes to a "low resistance" state, such as an electrically conductive state. The switching element can have this function regardless of the polarity of the voltage.

The magnetoresistive effect element MTJ can switch the resistance value between a low resistance state and a high resistance state by controlling the current supplied by the switching element SEL. The magnetoresistive effect element MTJ functions as a memory element that can write data based on changes in the resistance state and can store and read the written data in a non-volatile manner.

Next, the cross-sectional structure of the memory cell array 10 will be described using FIGS. 3 and 4 . 3 and 4 show an example of a cross-sectional view for explaining the structure of the memory cell array of the magnetic memory device according to the first embodiment. 3 and 4 are respectively cross-sectional views of the memory cell array 10 viewed from different intersecting directions.

As shown in FIGS. 3 and 4 , the memory cell array 10 is disposed on the semiconductor substrate 20 . In the following description, the plane parallel to the surface of the semiconductor substrate 20 is referred to as the XY plane, and the axis perpendicular to the XY plane is referred to as the Z axis. In addition, in the XY plane, let the axis along the word line WL be the X-axis, and let the axis along the bit line BL be the Y-axis. That is, FIG. 3 and FIG. 4 are cross-sectional views of the memory cell array 10 when viewed along the Y-axis and the X-axis respectively.

For example, a plurality of conductors 21 are provided on the upper surface of the semiconductor substrate 20 . The plurality of conductors 21 have electrical conductivity and function as word lines WLd. The plurality of conductors 21 are arranged in an array along the Y-axis, for example, and each extends along the X-axis. In addition, in FIGS. 3 and 4 , the case where a plurality of conductors 21 are provided on the semiconductor substrate 20 has been described, but the invention is not limited to this. For example, the plurality of conductors 21 may not be in contact with the semiconductor substrate 20 but may be provided spaced apart from each other above.

On the upper surface of one conductor 21, a plurality of elements 22 each functioning as a switching element SELd are provided. A plurality of elements 22 provided on the upper surface of one conductor 21 are arranged in an array along the X-axis, for example. That is, a plurality of elements 22 arranged along the X-axis are commonly connected to the upper surface of one conductor 21 .

On the upper surface of each of the plurality of elements 22, an element 23 each functioning as a magnetoresistive effect element MTJd is provided. In addition, the details of the structure of the component 23 will be described later. The upper surface of each of the plurality of elements 23 is connected to any one of the plurality of conductors 24 . The plurality of conductors 24 have electrical conductivity and function as bit lines BL. The plurality of conductors 24 are arranged in an array along the X-axis, for example, and each extends along the Y-axis. That is, a plurality of elements 23 arranged along the Y-axis are connected to one conductor 24 in common. In addition, in FIGS. 3 and 4 , the case where each of the plurality of elements 23 is connected to the upper surface of the element 22 and the lower surface of the conductor 24 has been described, but the invention is not limited to this. For example, each of the plurality of components 23 may be connected to the component 22 and the conductor 24 through a conductive contact plug (not shown).

A plurality of elements 25 each functioning as a switching element SELu are provided on the upper surface of one conductor 24 . A plurality of elements 25 provided on the upper surface of one conductor 24 are arranged in an array along the X-axis, for example. That is, a plurality of elements 25 arranged along the Y-axis are commonly connected to the upper surface of one conductor 24 .

On the upper surface of each of the plurality of elements 25, an element 26 functioning as a magnetoresistive effect element MTJu is provided. In addition, the element 26 has the same structure as the element 23, for example. The upper surface of each of the plurality of elements 26 is connected to any one of the plurality of conductors 27 . The plurality of conductors 27 have electrical conductivity and function as word lines WLu. The plurality of conductors 27 are arranged in an array along the Y-axis, for example, and each extends along the X-axis. That is, a plurality of elements 26 arranged along the X-axis are connected to one conductor 27 in common. In addition, in FIGS. 3 and 4 , the case where each of the plurality of elements 26 is connected to the upper surface of the element 25 and the lower surface of the conductor 27 has been described, but the invention is not limited to this. For example, each of the plurality of components 26 may be connected to the component 25 and the conductor 27 through a conductive contact plug (not shown).

With the above configuration, the memory cell array 10 has a structure in which one bit line BL corresponds to a set of two word lines WLd and WLu. Furthermore, the memory cell array 10 has the memory cell MCd between the word line WLd and the bit line BL, and the memory cell MCu between the bit line BL and the word line WLu. That is, the memory cell array 10 has a structure in which a plurality of memory cells MC are arranged at different heights along the Z-axis. In the cell structures shown in Figures 3 and 4, the memory cell MCd establishes a corresponding relationship with the lower layer, and the memory cell MCu establishes a corresponding relationship with the upper layer. That is, among the two memory cells MC commonly connected to one bit line BL, the memory cell MC arranged on the upper layer of the bit line BL corresponds to the memory cell MCu with the suffix "u", which is arranged on the lower layer. Memory cell MC corresponds to memory cell MCd with the suffix "d".

[1-1-3] Magnetoresistive effect element Next, the structure of the magnetoresistance effect element of the magnetic memory device according to the first embodiment will be described using FIG. 5 . FIG. 5 is a cross-sectional view for explaining the structure of the magnetoresistance effect element of the magnetic memory device according to the first embodiment. In FIG. 5 , for example, an example of a cross-section of the magnetoresistive effect element MTJd shown in FIGS. 3 and 4 is shown along a plane perpendicular to the Z-axis (for example, the XZ plane). In addition, since the magnetoresistive effect element MTJu has the same structure as the magnetoresistive effect element MTJd, its illustration is omitted.

As shown in FIG. 5 , the magnetoresistive effect element MTJ includes, for example, a nonmagnetic layer 31 functioning as a top layer TOP (Top layer), a nonmagnetic layer 32 functioning as a capping layer CAP (Capping layer), and a memory layer SL ( The ferromagnetic layer 33 that functions as a storage layer), the non-magnetic layer 34 that functions as a tunnel barrier layer TB (Tunnel barrier layer), the laminate 35 that functions as a reference layer RL (Reference layer), the spacer layer SP ( The non-magnetic layer 36 that functions as a spacer layer, the laminate 37 that functions as a shift canceling layer SCL (Shift cancelling layer), and the laminate 38 that functions as a buffer layer BUF (Buffer layer). Each of the memory layer SL, the reference layer RL, and the shift cancellation layer SCL can be regarded as an integral ferromagnetic structure. The buffer layer BUF can be regarded as an integrally non-magnetic structure.

The magnetoresistive effect element MTJd, for example, is arranged in the order of the laminate 38, the laminate 37, the non-magnetic layer 36, the laminate 35, the non-magnetic layer 34 and the ferromagnetic layer from the word line WLd side to the bit line BL side (along the Z-axis direction). 33. The nonmagnetic layer 32 and the nonmagnetic layer 31 are laminated with a plurality of films in sequence. The magnetoresistance effect element MTJu is arranged in the order of the laminate 38, the laminate 37, the non-magnetic layer 36, the laminate 35, the non-magnetic layer 34 and the ferromagnetic layer from the bit line BL side to the word line WLu side (along the Z-axis direction). 33. The nonmagnetic layer 32 and the nonmagnetic layer 31 are laminated with a plurality of films in sequence. For example, the magnetoresistance effect elements MTJd and MTJu function as a perpendicular magnetization type MTJ element in which the magnetization directions of the magnetic bodies constituting the magnetoresistance effect elements MTJd and MTJu are respectively oriented to the vertical direction with respect to the film surface. In addition, the magnetoresistive effect element MTJ may include further layers (not shown) between the above-mentioned layers 31 to 38 .

In the first embodiment, for example, a writing current is directly passed through the magnetoresistive element MTJ, and the writing current is used to inject spin torque into the memory layer SL and the reference layer RL, thereby controlling the memory layer SL. The magnetization direction and the magnetization direction of the reference layer RL are spin injection writing methods. The magnetoresistive effect element MTJ can obtain either a low resistance state or a high resistance state according to whether the relative relationship between the magnetization directions of the memory layer SL and the reference layer RL is parallel or antiparallel.

If a write current IwAPP of a certain size flows in the magnetoresistive element MTJ in the direction of the arrow A1 in Figure 5, that is, from the memory layer SL toward the reference layer RL, then the memory layer SL and the reference layer RL The relative relationship between magnetization directions is parallel. In this parallel state, the resistance value of the magnetoresistive effect element MTJ is the lowest, and the magnetoresistive effect element MTJ is set to a low resistance state. This low-resistance state is called a "P (Parallel) state" and is defined as a state of data "0", for example.

Furthermore, in the magnetoresistive element MTJ, in the direction of arrow A2 in FIG. 5 , that is, in the direction from the reference layer RL toward the memory layer SL (the opposite direction to the arrow A1), a larger write current IwAPP flows. When the writing current IwPAP is applied, the relative relationship between the magnetization directions of the memory layer SL and the reference layer RL is antiparallel. In the case of this anti-parallel state, the resistance value of the magnetoresistive effect element MTJ is the highest, and the magnetoresistive effect element MTJ is set to a high resistance state. This high-resistance state is called an "AP (Anti-Parallel, anti-parallel) state" and is defined as a state of data "1", for example.

Next, the details of the structure of each layer of the magnetoresistive effect element MTJ will be described.

The non-magnetic layer 31 is a non-magnetic conductor and functions as a top electrode to improve the electrical connection between the upper end of the magnetoresistive element MTJ and the bit line BL or word line WL. The nonmagnetic layer 31 includes, for example, tungsten (W), tantalum (Ta), molybdenum (Mo), hafnium (Hf), ruthenium (Ru), tantalum nitride (TaN), titanium (Ti), and titanium nitride ( TiN) at least one element or compound. Or, it contains a layered body containing at least one element or compound selected from the aforementioned materials.

The nonmagnetic layer 32 is a nonmagnetic layer and has the function of suppressing an increase in the damping constant of the ferromagnetic layer 33 and reducing the write current. The nonmagnetic layer 32 contains, for example, an alkaline earth element or a rare earth element and oxygen, or substantially contains an alkaline earth metal oxide or a rare earth element oxide. As an example, it contains oxygen and magnesium, or substantially contains magnesium oxide (MgO). Likewise, it contains oxygen and aluminum, or substantially contains aluminum oxide (Al ₂ O ₃ ). In addition, the non-magnetic layer 32 may be a mixture of these oxides. That is, the nonmagnetic layer 32 is not limited to a binary compound containing two elements, but may include a ternary compound containing three elements, such as magnesium aluminum oxide (MgAlO).

The ferromagnetic layer 33 has ferromagnetism and has an easy magnetization axis in the direction perpendicular to the film surface. The ferromagnetic layer 33 has a magnetization direction along the Z-axis toward either the bit line BL side or the word line WL side. The ferromagnetic layer 33 may include at least any one of iron (Fe), cobalt (Co), and nickel (Ni). In addition, the ferromagnetic layer 33 may further contain boron (B). More specifically, for example, the ferromagnetic layer 33 may include iron cobalt boron (FeCoB) or iron boride (FeB) and have a body-centered cubic crystal structure.

The nonmagnetic layer 34 is a nonmagnetic insulator, for example, containing oxygen and magnesium, or substantially containing magnesium oxide (MgO). The nonmagnetic layer 34 has a NaCl crystal structure in which the film surface is oriented to the (001) plane, and serves as a crystal nucleus for growing a crystalline film from the interface with the ferromagnetic layer 33 during the crystallization process of the ferromagnetic layer 33 The sheet material functions. The nonmagnetic layer 34 is provided between the ferromagnetic layer 33 and the laminate 35, and forms a magnetic tunnel junction together with the two ferromagnetic bodies.

The laminate 35 can be regarded as a ferromagnetic layer as a whole, and has an easy magnetization axis in the direction perpendicular to the film surface. The laminated body 35 has a magnetization direction along the Z-axis toward either the bit line BL side or the word line WL side. The magnetization direction of the laminated body 35 is fixed and faces the direction of the laminated body 37 in the example of FIG. 5 . In addition, “the magnetization direction is fixed” means that the magnetization direction does not change due to a current (spin torque) of a magnitude that can reverse the magnetization direction of the ferromagnetic layer 33 .

More specifically, the laminated body 35 includes a ferromagnetic layer 35a functioning as an interface layer IL (Interface layer), a nonmagnetic layer 35b functioning as a functional layer FL (Function layer), and a main reference layer MRL (Main). Reference layer) functions as a ferromagnetic layer 35c. For example, a ferromagnetic layer 35c, a nonmagnetic layer 35b, and a ferromagnetic layer 35a are sequentially stacked between the upper surface of the nonmagnetic layer 36 and the lower surface of the nonmagnetic layer 34.

The ferromagnetic layer 35a is a ferromagnetic conductor, and may include at least any one of iron (Fe), cobalt (Co), and nickel (Ni), for example. In addition, the ferromagnetic layer 35a may further contain boron (B). More specifically, for example, the ferromagnetic layer 35a may include iron cobalt boron (FeCoB) or iron boride (FeB) and have a body-centered cubic crystal structure.

The non-magnetic layer 35b is a non-magnetic conductor, and may include, for example, tantalum (Ta), hafnium (Hf), tungsten (W), zirconium (Zr), molybdenum (Mo), niobium (Nb), and titanium (Ti). ) of at least one metal. The nonmagnetic layer 35b has the function of maintaining exchange coupling between the ferromagnetic layer 35a and the ferromagnetic layer 35c.

The ferromagnetic layer 35c may include, for example, a multilayer film of cobalt (Co) and platinum (Pt) (Co/Pt multilayer film), a multilayer film of cobalt (Co) and nickel (Ni) (Co/Ni multilayer film), and At least one type of multilayer film of cobalt (Co) and palladium (Pd) (Co/Pd multilayer film). Alternatively, it may be a CoPt, CoPd, CoNi film or a Co single-layer film containing at least Co. In addition, the layer in contact with the non-magnetic layer 36 among the multi-layer films or single-layer films constituting the ferromagnetic layer 35c contains, for example, cobalt (Co).

The nonmagnetic layer 36 is a nonmagnetic conductor, and includes, for example, at least one element selected from the group consisting of ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), vanadium (V), and chromium (Cr). The nonmagnetic layer 36 has a function of coupling the magnetization of the laminated body 35 and the magnetization of the laminated body 37 antiparallelly.

The laminate 37 can be regarded as a ferromagnetic layer as a whole, and has an easy magnetization axis in the direction perpendicular to the film surface. The laminated body 37 has a magnetization direction along the Z-axis toward either the bit line BL side or the word line WL side. The magnetization direction of the laminated body 37 is fixed similarly to the laminated body 35, and in the example of FIG. 5, it faces the direction of the laminated body 35.

More specifically, the laminated body 37 includes a ferromagnetic layer 37a (ML1), a nonmagnetic layer 37b (ML2), a ferromagnetic layer 37c (ML3), a nonmagnetic layer 37c (ML3), and a ferromagnetic layer 37c (ML3). Layer 37d (ML4), ferromagnetic layer 37e (ML5), nonmagnetic layer 37f (ML6), ferromagnetic layer 37g (ML7), and nonmagnetic layer 37h (ML8). For example, between the upper surface of the laminated body 38 and the lower surface of the nonmagnetic layer 36, a nonmagnetic layer 37h, a ferromagnetic layer 37g, a nonmagnetic layer 37f, a ferromagnetic layer 37e, a nonmagnetic layer 37d, and a ferromagnetic layer are sequentially laminated. Layer 37c, nonmagnetic layer 37b, and ferromagnetic layer 37a.

The ferromagnetic layer 37a is a ferromagnetic conductor having a hexagonal close-packed structure (hcp: Hexagonal close-packed) or a face-centered cubic (fcc: face-centered cubic) crystal structure, and contains, for example, cobalt (Co). Ferromagnetic layers 35c and 37a are antiferromagnetically coupled via nonmagnetic layer 36 . That is, the ferromagnetic layer 35c (more specifically, the layer in contact with the nonmagnetic layer 36 among the multilayer films constituting the ferromagnetic layer 35c) and the ferromagnetic layer 37a are coupled so as to have mutually antiparallel magnetization directions. . Therefore, in the example of FIG. 5 , the magnetization directions of the ferromagnetic layers 35 c and 37 a are in opposite directions to each other. Such a coupling structure of the ferromagnetic layer 35c, the nonmagnetic layer 36, and the ferromagnetic layer 37a is called a SAF (Synthetic Anti-Ferromagnetic) structure.

The nonmagnetic layer 37b is a nonmagnetic conductor and includes platinum (Pt). The ferromagnetic layer 37c is a ferromagnetic conductor and contains cobalt (Co). The nonmagnetic layer 37d is a nonmagnetic conductor and contains platinum (Pt). The ferromagnetic layer 37e is a ferromagnetic conductor and contains cobalt (Co). The nonmagnetic layer 37f is a nonmagnetic conductor and includes platinum (Pt). The ferromagnetic layer 37g is a ferromagnetic conductor and contains cobalt (Co). The nonmagnetic layer 37h is a nonmagnetic conductor, including platinum (Pt). The nonmagnetic layer 37h has a face-centered cubic crystal structure in which the film surface is aligned with the (111) plane.

In addition, in the example of FIG. 5 , the case where four sets of magnetic layers and non-magnetic layers are stacked on the laminate 37 is shown. However, five or more sets of ferromagnetic layers and non-magnetic layers may be stacked, or two sets may be stacked. ~3 groups. That is, a multilayer film of cobalt (Co) and platinum (Pt) can be formed by laminating a plurality of ferromagnetic layers and nonmagnetic layers.

According to the above configuration, the laminated body 37 can offset the influence of the leakage magnetic field of the laminated body 35 on the magnetization direction of the ferromagnetic layer 33 . Therefore, it is suppressed that the leakage magnetic field of the laminated body 35 causes asymmetry in the easy reversal of the magnetization of the ferromagnetic layer 33 (that is, the easy reversal of the magnetization of the ferromagnetic layer 33 when the direction of the magnetization is reversed is suppressed). The situation of reversal from one to the other and the situation of reversal from one to the other are different).

The laminate 38 can be regarded as a non-magnetic layer as a whole, and has the function of an electrode to improve the electrical connection with the bit line BL and the word line WL. Specifically, the laminate 38 includes a nonmagnetic layer 38a (BUF1) and a nonmagnetic layer 38b (BUF2) that each function as one of the buffer layers BUF. For example, in the case of FIGS. 3 and 4 , the nonmagnetic layer 38b and the nonmagnetic layer 38a are sequentially stacked along the Z-axis between the semiconductor substrate 20 and the lower surface of the laminate 37 constituting the element 23 . Furthermore, a nonmagnetic layer 38b and a nonmagnetic layer 38a are sequentially stacked along the Z-axis between the bit line BL and the lower surface of the laminate 37 constituting the element 26.

The nonmagnetic layer 38a is a metal oxide film. The nonmagnetic layer 38a is a nonmagnetic conductor, and is a metal oxide with an electronegativity of 1.8 or less, such as gallium oxide (GdO _x ) or aluminum oxide (AlO _x ). The thickness of the nonmagnetic layer 38a is, for example, 1.0 nm. The nonmagnetic layer 38a has an amorphous structure and has a small bonding energy with a noble metal such as platinum (Pt). Thereby, the nonmagnetic layer 38a has the function of promoting the crystallization of the nonmagnetic layer 37h during the film formation of the nonmagnetic layer 37h.

The nonmagnetic layer 38b is a nonmagnetic conductor, including at least one selected from the group consisting of titanium nitride (TiN), hafnium nitride (HfN), zirconium nitride (ZrN), tantalum nitride (TaN), and tungsten nitride (WN). A compound.

[1-2]Effect According to the first embodiment, the external magnetic field resistance of the magnetoresistive effect element can be improved.

The reference layer of the magnetoresistive element MTJ must be magnetized and not reversed during writing, reading and memory retention. In order to suppress false inversion during writing, reading and memory retention of the reference layer, it is necessary to increase the anisotropic magnetic field of the shift cancellation layer that is magnetically coupled anti-parallel to the reference layer.

FIG. 6 is a graph illustrating the relationship between the film properties of the shift eliminating layer of the first embodiment before device processing and the device properties after processing. The horizontal axis represents the anisotropic magnetic field (Hk) of the film of the displacement elimination layer. The vertical axis represents the coercive force (Hc) of the film of the displacement elimination layer. The chain line represents the line where the spin-flip magnetic field (Hsw) of the inverted element is equal to a certain value Hsw0 when the reference layer and the shift cancellation layer remain anti-parallel. The value Hsw0 is, for example, the Hsw of an element that exists with a probability of -3σ when the spin-flip magnetic field (Hsw) of multiple elements is normally distributed. On the right side of the hinge line, the spin-flip magnetic field (Hsw) of the -3σ component is higher than the value Hsw0. On the left side of the hinge line, the spin-flip magnetic field (Hsw) of the -3σ component ) magnetic field (Hsw) is lower than the value Hsw0. In Figure 6, two plot points P1 and P2 are shown. Plotted point P1 represents a comparative example in which no metal oxide is used in the buffer layer. The spin-flip magnetic field (Hsw) of the element plotted at point P1 is lower than the value Hsw0. Plot point P2 corresponds to the first embodiment. Compared with the plotted point P1, the anisotropic magnetic field (Hk) of the shift cancellation layer is higher at plot point P2, and the spin-flip magnetic field (Hsw) of the element is higher than the value Hsw0. In this way, according to the first embodiment, by maintaining the coercive force (Hc) of the displacement elimination layer, which is a film characteristic before device processing, and increasing the anisotropic magnetic field (Hk), the probability of existence at -3σ can be increased. The spin-flip magnetic field (Hsw) of the component.

The anisotropic magnetic field of the shift canceling layer becomes higher when the crystallinity of the shift canceling layer is increased. In the first embodiment, for the nonmagnetic layer 38a of the buffer layer adjacent to the shift elimination layer, a metal oxide having an amorphous structure and a negative conductivity of 1.8 or less is used. In addition, the nonmagnetic layer 37h adjacent to the shift elimination layer contains platinum (Pt). The binding energy between metal oxides with an amorphous structure and platinum (Pt) is small. Furthermore, platinum (Pt) is preferentially aligned on the (111) plane. Therefore, the crystallization of platinum (Pt) is promoted in the nonmagnetic layer 37h adjacent to the nonmagnetic layer 38a of an amorphous structure. Therefore, according to the first embodiment, it is possible to provide a shift cancellation layer with high crystallinity, that is, a shift cancellation layer with a high anisotropic magnetic field.

In this way, according to the first embodiment, a shift cancellation layer with a high anisotropic magnetic field can be provided. Since the reversal magnetic field of the reference layer becomes high, the external magnetic field resistance of the magnetoresistive element MTJ can be improved.

In addition, as a method of providing a shift elimination layer with high crystallinity, a method of providing a layer of platinum (Pt), ruthenium (Ru), iridium (Ir), etc. with a thickness of approximately 2.0 nm is also considered in the buffer layer. In the first embodiment, the thickness of the non-magnetic layer 38a is, for example, 1.0 nm. Compared with the case where a layer of platinum (Pt), ruthenium (Ru), iridium (Ir), etc. is provided with a thickness of about 2.0 nm, the buffer can be thinned. layer. Thereby, the magnetic memory device of the first embodiment can further integrate the magnetoresistive effect element MTJ into a higher density.

[2] Second embodiment The magnetic memory device of the second embodiment is different from the magnetic memory device of the first embodiment in the structure of the laminate 38 of the magnetoresistive effect element MTJ. Hereinafter, the differences between the magnetoresistive effect element of the second embodiment and the first embodiment will be described.

[2-1]Composition [2-1-1] Magnetoresistive effect element 7 is a cross-sectional view for explaining the structure of the magnetoresistance effect element of the magnetic memory device according to the second embodiment. The magnetoresistive effect element of the second embodiment is different from the magnetoresistive effect element of the first embodiment in that the laminate 38 further includes a non-magnetic layer 38c.

The laminate 38 can be regarded as a non-magnetic layer as a whole, and has the function of an electrode to improve the electrical connection with the bit line BL and the word line WL. Specifically, the laminate 38 includes a nonmagnetic layer 38a (BUF1), a nonmagnetic layer 38c (BUF3), and a nonmagnetic layer 38b (BUF2) that each function as one of the buffer layers BUF. For example, in the case of FIGS. 3 and 4 , the nonmagnetic layer 38b and the nonmagnetic layer 38a are sequentially stacked along the Z-axis between the semiconductor substrate 20 and the lower surface of the laminate 37 constituting the element 23 . Furthermore, a nonmagnetic layer 38b and a nonmagnetic layer 38a are sequentially stacked along the Z-axis between the bit line BL and the lower surface of the laminate 37 constituting the element 26.

The non-magnetic layer 38c is a non-magnetic conductor, including titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum At least one element of (Mo), tungsten (W), carbon (C), silicon (Si), and germanium (Ge). The nonmagnetic layer 38b has the function of reducing the resistance of the laminated body 38.

The other structures of the magnetoresistive effect element of the second embodiment are the same as those of the first embodiment.

[2-2]Effect According to the second embodiment, similarly to the first embodiment, the external magnetic field resistance of the magnetoresistive effect element can be improved. Furthermore, according to the second embodiment, it is possible to suppress a decrease in the MR ratio.

In the second embodiment, the nonmagnetic layer 38c is provided under the nonmagnetic layer 38a of an amorphous structure. By providing the nonmagnetic layer 38c, the resistance of the laminated body 38 is reduced. Thereby, the ratio of the resistance value in the high-resistance state and the resistance value in the low-resistance state of the magnetoresistive effect element MTJ, that is, the MR ratio can be suppressed from decreasing.

[3]Others The memory cell MC described in the above-mentioned embodiment has been described in the case where the magnetoresistive effect element MTJ is disposed above the switching element SEL. However, the magnetoresistive effect element MTJ may be disposed below the switching element SEL.

In the above embodiment, the case where the magnetoresistive effect element MTJ is provided on the upper surface of the switching element SEL has been described. However, a conductor may be provided between the switching element SEL and the magnetoresistive effect element MTJ. 8 and 9 show an example of a cross-sectional view for explaining the structure of a memory cell array of a magnetic memory device according to a modified example. The cross-section shown in FIG. 8 corresponds to the cross-section shown in FIG. 3 . The cross-section shown in Figure 9 corresponds to the cross-section shown in Figure 4. Conductors 28 are respectively provided on the upper surfaces of each of the plurality of components 22 . The electrical conductor 28 has electrical conductivity. The element 23 is provided on the upper surface of each of the plurality of conductors 28 . Conductors 29 are respectively provided on the upper surfaces of each of the plurality of elements 25 . The conductor 29 has electrical conductivity. The element 26 is provided on the upper surface of each of the plurality of conductors 29 . The other structures of the magnetic memory device of the modified example are the same as those of the magnetic memory device of the first embodiment. According to the modified example, similarly to the first embodiment or the second embodiment, the external magnetic field resistance of the magnetoresistive effect element can be improved.

In the above embodiment, the case where the laminated body 38 includes the nonmagnetic layer 38b has been described, but the nonmagnetic layer 38b may be omitted. For example, when the nonmagnetic layer 38b is omitted in the first embodiment, the lower end of the magnetoresistance effect element MTJ is the nonmagnetic layer 38a. For example, when the nonmagnetic layer 38b is omitted in the second embodiment, the lower end of the magnetoresistance effect element MTJ is the nonmagnetic layer 38c. The lower end of the magnetoresistance effect element MTJ is connected to the switching element SEL in the example shown in the above-mentioned embodiment. The lower end of the magnetoresistive effect element MTJ is connected to the word line WL or the bit line BL when the magnetoresistive effect element MTJ is disposed below the switching element SEL. The lower end of the magnetoresistive effect element MTJ is connected to the conductor when the magnetoresistive effect element MTJ is disposed above the switching element SEL and a conductor is disposed between the switching element SEL and the magnetoresistive effect element MTJ.

In this specification, "connection" means electrical connection, for example, it does not exclude the use of other components therebetween. In addition, "electrical connection" may be through an insulator as long as it can operate in the same manner as an electrical connection.

Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the patent application and their equivalent scope.

[Reference to related applications] The application for this invention enjoys the priority of applications based on Japanese Patent Application No. 2022-046633 (filing date: March 23, 2022) and US Patent Application No. 17/942365 (filing date: September 12, 2022). right. The present application includes the entire contents of the basic application by reference to the basic application.

1: Magnetic memory device 10: Memory cell array 11: Column selection circuit 12: Row selection circuit 13: Decoding circuit 14:Writing circuit 15: Readout circuit 16: Voltage generation circuit 17: Input and output circuit 18:Control circuit 20:Semiconductor substrate 21:Conductor 22,23,25,26: components 24,27,28,29: conductor 31,32,34,35b,36,37b,37d,37f,37h,38a,38b,38c,BUF1,BUF2,BUF3,ML2,ML4,ML6,ML8: non-magnetic layer 33,35a,35c,37a,37c,37e,37g,ML1,ML3,ML5,ML7: ferromagnetic layer 35,37,38:Laminated body A1,A2: arrow ADD:address AP: anti-parallel BL, BL＜0＞~BL＜N＞: bit lines BUF: buffer layer CAP: covering layer CNT: control signal CMD: command DAT:data FL: functional layer IL: interface layer MC,MCd＜0,0＞~MCd＜0,N＞,MCd＜1,0＞~MCd＜1,N＞,MCd＜M,0＞~MCd＜M,N＞,MCu＜0,0＞ ~MCu＜0,N＞,MCu＜1,0＞~MCu＜1,N＞,MCu＜M,0＞~MCu＜M,N＞: memory cells MRL: main reference layer MTJ, MTJd, MTJd＜0,0＞, MTJu, MTJu＜0,0＞: magnetoresistive effect element P: parallel P1, P2: plot points RL: reference layer SCL: shift cancellation layer SELd, SELd＜0,0＞, SELu, SELu＜0,0＞: switching element SL: memory layer SP: spacer layer TB: tunneling barrier layer TOP: Top level WL, WLd, WLd＜0＞~WLd＜M＞, WLu, WLu＜0＞~WLu＜M＞: word lines X,Y,Z: axis

FIG. 1 is a block diagram showing the structure of the magnetic memory device according to the first embodiment. FIG. 2 is a circuit diagram showing the structure of the memory cell array of the magnetic memory device according to the first embodiment. FIG. 3 is a cross-sectional view illustrating the structure of the memory cell array of the magnetic memory device according to the first embodiment. FIG. 4 is a cross-sectional view illustrating the structure of the memory cell array of the magnetic memory device according to the first embodiment. FIG. 5 is a cross-sectional view for explaining the structure of the magnetoresistance effect element of the magnetic memory device according to the first embodiment. FIG. 6 is a graph illustrating the relationship between the film properties of the shift eliminating layer of the first embodiment before device processing and the device properties after processing. 7 is a cross-sectional view for explaining the structure of the magnetoresistance effect element of the magnetic memory device according to the second embodiment. 8 is a cross-sectional view illustrating the structure of a memory cell array of a magnetic memory device according to a modified example. FIG. 9 is a cross-sectional view illustrating the structure of a memory cell array of a magnetic memory device according to a modified example.

31,32,34,35b,36,37b,37d,37f,37h,38a,38b,BUF1,BUF2,ML2,ML4,ML6,ML8: non-magnetic layer

33,35a,35c,37a,37c,37e,37g,ML1,ML3,ML5,ML7: ferromagnetic layer

35,37,38:Laminated body

A1,A2: arrow

AP: anti-parallel

BUF: buffer layer

CAP: covering layer

FL: functional layer

IL: interface layer

MRL: main reference layer

MTJ: magnetoresistance element

P: parallel

RL: reference layer

SCL: shift cancellation layer

SL: memory layer

SP: spacer layer

TB: tunneling barrier layer

TOP: Top level

X,Y,Z: axis

Claims (15)

A magnetic memory device including a magnetoresistive effect element; and The aforementioned magnetoresistive effect elements include: 1st ferromagnetic layer; 2nd ferromagnetic layer; A laminate in which the second ferromagnetic layer is provided on the opposite side to the first ferromagnetic layer; a first nonmagnetic layer disposed between the first ferromagnetic layer and the second ferromagnetic layer; a second nonmagnetic layer provided between the second ferromagnetic layer and the laminate; and a third nonmagnetic layer, which is provided on the opposite side of the laminate to the second nonmagnetic layer and contains a metal oxide; and The laminated body includes a fourth nonmagnetic layer that is in contact with the third nonmagnetic layer and contains platinum (Pt). The magnetic memory device of claim 1, wherein the third non-magnetic layer contains gallium (Gd) or aluminum (Al). The magnetic memory device of claim 1, wherein the third non-magnetic layer contains an oxide of a metal element with a negative electronegativity less than 1.8. The magnetic memory device of claim 1, wherein the aforementioned laminate further includes: a third ferromagnetic layer, which is in contact with the fourth non-magnetic layer on the opposite side to the third non-magnetic layer; a fifth nonmagnetic layer that is in contact with the third ferromagnetic layer on the opposite side to the fourth nonmagnetic layer from the third ferromagnetic layer; and The fourth ferromagnetic layer is in contact with the fifth nonmagnetic layer on the opposite side to the third ferromagnetic layer from the fifth nonmagnetic layer. The magnetic memory device of claim 4, wherein the fifth non-magnetic layer contains platinum (Pt); and The third ferromagnetic layer and the fourth ferromagnetic layer contain cobalt (Co). The magnetic memory device of claim 1, wherein the aforementioned laminate further includes: a third ferromagnetic layer, which is in contact with the fourth non-magnetic layer on the opposite side to the aforementioned third non-magnetic layer; and A sub-laminated body in which the third ferromagnetic layer is in contact with the third ferromagnetic layer on the side opposite to the fourth non-magnetic layer; and The aforementioned sub-laminated body includes a plurality of sixth non-magnetic layers and a plurality of fifth ferromagnetic layers; The sub-laminated body has a plurality of laminated groups in which the sixth nonmagnetic layer and the fifth ferromagnetic layer are laminated in the order of the sixth nonmagnetic layer and the fifth ferromagnetic layer from the side of the third ferromagnetic layer. its structure. The magnetic memory device of claim 6, wherein the sixth non-magnetic layer contains platinum (Pt); and The third ferromagnetic layer and the fifth ferromagnetic layer contain cobalt (Co). The magnetic memory device of claim 1, wherein the magnetoresistive effect element further includes a seventh nonmagnetic layer, and the seventh nonmagnetic layer is opposite to the third nonmagnetic layer from the laminate on the opposite side to the third nonmagnetic layer. layers are connected; and The seventh nonmagnetic layer includes at least one compound selected from titanium nitride (TiN), hafnium nitride (HfN), zirconium sulfide (ZrN), tantalum nitride (TaN), and tungsten nitride (WN). The magnetic memory device of claim 1, wherein the magnetoresistance effect element further includes an eighth nonmagnetic layer, and the eighth nonmagnetic layer is opposite to the third nonmagnetic layer from the laminate on the opposite side to the third nonmagnetic layer. layers are connected; and The aforementioned eighth non-magnetic layer includes titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten At least one element of (W), carbon (C), silicon (Si), and germanium (Ge). The magnetic memory device of claim 9, wherein the magnetoresistive effect element further includes a ninth non-magnetic layer, and the ninth non-magnetic layer is on the opposite side of the aforementioned third non-magnetic layer to the aforementioned eighth non-magnetic layer and the aforementioned third non-magnetic layer. 8 non-magnetic layers are connected; and The ninth nonmagnetic layer includes at least one compound selected from titanium nitride (TiN), hafnium nitride (HfN), zirconium nitride (ZrN), tantalum nitride (TaN), and tungsten nitride (WN). The magnetic memory device of claim 1, wherein the third non-magnetic layer is amorphous. The magnetic memory device of claim 1, wherein the second non-magnetic layer includes a material selected from the group consisting of ruthenium (Ru), osmium (Os), rhodium (Rh), iridium (Ir), vanadium (V), and chromium (Cr). At least one element. The magnetic memory device of claim 1, wherein the first non-magnetic layer contains magnesium oxide (MgO). The magnetic memory device of claim 1, further comprising a substrate; and In a direction perpendicular to the surface of the substrate, the substrate, the third nonmagnetic layer, the laminated body, the second nonmagnetic layer, the second ferromagnetic layer, the first nonmagnetic layer, and the 1st ferromagnetic layer. The magnetic memory device of claim 14, wherein the substrate is not in contact with the third non-magnetic layer.