WO2021000747A1 - Magnetic storage device based on spin orbit torque, and sot-mram storage unit - Google Patents

Abstract

Provided are a magnetic storage device based on a spin orbit torque, and an SOT-MRAM storage unit. The magnetic storage device comprises: a spin orbit torque supply line, a magnetic tunnel junction located on a surface of one side of the spin orbit torque supply line, and a dielectric layer located on a surface of the other side of the spin orbit torque supply line, wherein one side of a free layer of the magnetic tunnel junction is close to the spin orbit torque supply line, and the horizontal length of the spin orbit torque supply line is greater than the feature length of the magnetic tunnel junction; and the dielectric layer is provided, in the vertical direction, with a conductive hole penetrating through the dielectric layer, and the position of the conductive hole in the horizontal direction corresponds to the position of the magnetic tunnel junction, and the conductive hole is used for providing a conductive path vertical to the spin orbit torque supply line. According to the present invention, the read disturbance during a reading process can be reduced.

Description

Magnetic memory device and SOT-MRAM memory cell based on spin-orbit moment Technical field

The present invention relates to the technical field of magnetic memory, in particular to a magnetic storage device and SOT-MRAM storage unit based on spin-orbit moment.

Background technique

In response to the traditional STT-MRAM (Spin Transfer Torque Magnetic Random Access Memory, Spin Transfer Torque Magnetic Random Access Memory) that requires a higher write voltage, the industry has proposed a SOT-MRAM (Spin Orbit Torque Magnetic Random Access Memory). Spin-orbital moment magnetic random access memory), using spin-orbital moment to realize fast and reliable magnetization reversal. This writing technology requires a spin-orbital moment supply line to be added under the free layer of the magnetic tunnel junction. The current flowing through the spin-orbital moment supply line can induce a torque to drive the magnetization inversion of the free layer. In addition to the spin Hall effect, the Rashba effect, the spin-orbit moment effect of unknown mechanism, etc. may all have similar effects.

The structure of the existing SOT-MRAM memory cell is shown in Figure 1. During the read operation, the selector tube on the RWL is turned on, the read bias voltage is applied between BL and SL, the read current flows through the MTJ, and the spin orbit moment The supply line flows horizontally for a certain distance, causing the SOT effect.

In the process of implementing the present invention, the inventor found that at least the following technical problems exist in the prior art:

When the existing SOT-MRAM memory cell reads data, due to the addition of the SOT effect, the read current generates read disturbances, resulting in data read errors.

Summary of the invention

In order to solve the above-mentioned problems, the present invention provides a magnetic storage device and SOT-MRAM storage unit based on spin-orbit moment, which can reduce the read disturbance during the reading process.

In a first aspect, the present invention provides a magnetic storage device based on a spin orbital moment, comprising: a spin-orbital moment supply line, a magnetic tunnel junction located on one side surface of the spin-orbital moment supply line, and The orbital moment provides the dielectric layer on the other side of the line, where

A side of the free layer of the magnetic tunnel junction is close to the spin-orbit moment providing line, and the horizontal length of the spin-orbit moment providing line is greater than the characteristic length of the magnetic tunnel junction;

The dielectric layer is provided with a conductive hole passing through the dielectric layer in a vertical direction, and the position of the conductive hole in the horizontal direction corresponds to the position of the magnetic tunnel junction, and is used to provide a hole perpendicular to the spin The orbital moment provides the conductive path of the wire.

Optionally, the conductive hole is made of a high-resistivity material, including one of titanium (Ti), tantalum (Ta), and β-phase-tungsten (W).

Optionally, the conductive hole has a multilayer structure, wherein a layer of material that provides line contact with the spin-orbit moment is a high-resistivity material, including titanium (Ti), tantalum (Ta), and β-phase-tungsten ( One of W).

Optionally, the material of the spin-orbit moment providing line is a heavy metal material, including platinum (Pt), tantalum (Ta), tungsten (W), iridium (Ir), hafnium (Hf), ruthenium (Ru), thallium (Tl), bismuth (Bi), gold (Au), titanium (Ti), and osmium (Os).

Optionally, the spin-orbit moment providing line adopts a multi-segment structure in the horizontal direction, wherein the position overlapping with the magnetic tunnel junction is a heavy metal material, including platinum (Pt), tantalum (Ta), and tungsten (W) , Iridium (Ir), hafnium (Hf), ruthenium (Ru), thallium (Tl), bismuth (Bi), gold (Au), titanium (Ti), and osmium (Os).

Optionally, the spin-orbit moment providing line adopts a multilayer structure in the vertical direction, wherein the layer in contact with the magnetic tunnel junction is a heavy metal material, including platinum (Pt), tantalum (Ta), tungsten (W ), iridium (Ir), hafnium (Hf), ruthenium (Ru), thallium (Tl), bismuth (Bi), gold (Au), titanium (Ti), and osmium (Os).

In a second aspect, the present invention provides a SOT-MRAM memory cell, comprising: the above-mentioned spin-orbital moment-based magnetic memory device, further comprising: a first transistor and a second transistor, wherein the first transistor is used to control a read operation, The second transistor is used to control the write operation,

One side of the fixed layer of the magnetic tunnel junction is connected to a bit line, the conductive hole is connected to the drain of the first transistor, the gate of the first transistor is connected to the read word line, and the The source is connected to the source line;

The end of the spin-orbit moment providing line in the horizontal direction away from the magnetic tunnel junction is connected to the drain of the second transistor, the gate of the second transistor is connected to the writing line, and the source of the second transistor The pole is connected to the source line.

In a third aspect, the present invention provides a SOT-MRAM memory cell, comprising: the above-mentioned spin-orbital moment-based magnetic memory device, further comprising: a third transistor and a bidirectional controllable switching device, wherein the third transistor is used for For controlling the read operation and the write operation, the bidirectional controllable switch device is used to form a current path for the write operation;

One side of the fixed layer of the magnetic tunnel junction is connected to a bit line, the conductive hole is connected to the drain of the third transistor, and the end of the spin-orbit moment providing line in the horizontal direction away from the magnetic tunnel junction passes through The bidirectional controllable switch device is connected to the drain of the third transistor, the gate of the third transistor is connected to the word line, and the source of the third transistor is connected to the source line.

In the magnetic storage device and SOT-MRAM memory cell based on the spin orbital moment provided by the present invention, in the reading process, the reading current flows through the conductive path formed by the conductive hole, instead of passing through the spin orbit moment supply line, the reading current is In the vertical direction, the spin-orbit moment provides a read current that does not flow horizontally in the line, thereby reducing the read disturbance caused by the SOT effect on the read current and reducing the read error rate of the device.

Description of the drawings

FIG. 1 is a schematic diagram of the structure of an existing SOT-MRAM memory cell;

2 is a schematic structural diagram of a magnetic storage device based on a spin-orbit moment according to an embodiment of the present invention;

3 is a schematic diagram of the structure of a SOT-MRAM memory cell according to an embodiment of the present invention;

4 is a schematic structural diagram of a SOT-MRAM memory cell according to another embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is only a part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

An embodiment of the present invention provides a magnetic storage device based on a spin orbital moment. As shown in FIG. 2, the magnetic storage device includes: a spin orbital moment supply line 10, and a surface on one side of the spin orbital moment supply line 10 The magnetic tunnel junction (abbreviated as MTJ in the subsequent discussion) 20 and the dielectric layer 30 on the other side surface of the spin-orbit moment supply line 10, wherein,

The MTJ 20 includes a free layer 201, a barrier layer 202, and a fixed layer (also referred to as a reference layer) 203. The free layer side 201 of the MTJ is close to the spin orbit moment supply line 10, and the spin orbit moment supply line The horizontal length of 10 is greater than the characteristic length of MTJ20. In this embodiment, MTJ20 is located at one end of the spin orbital moment providing line 10 in the horizontal direction;

The dielectric layer 30 is provided with a conductive hole 40 passing through the dielectric layer 30 in a vertical direction. The material of the dielectric layer 30 is an insulating dielectric. The position of the conductive hole 40 in the horizontal direction is the same as that of the MTJ20. Correspondingly, it is used to provide a conductive path perpendicular to the spin orbit moment providing line.

Optionally, the conductive hole 40 in the above embodiment needs to have a relatively high resistance, so the conductive hole 40 uses a material with high resistivity, including but not limited to titanium (Ti), tantalum (Ta) and β-phase-tungsten (W ). Further, in order to make the conductive hole have better resistance characteristics, the conductive hole 40 may adopt a multilayer structure to modulate the resistance, wherein the layer of material that provides line contact with the spin orbital moment is a high-resistivity material , Including one of titanium (Ti), tantalum (Ta) and β phase-tungsten (W).

Further, the spin orbit moment providing line 10 is used to generate the spin orbit moment, and the material uses heavy metal materials, including platinum (Pt), tantalum (Ta), tungsten (W), iridium (Ir), hafnium (Hf), ruthenium (Ru), thallium (Tl), bismuth (Bi), gold (Au), titanium (Ti), and osmium (Os), but not limited thereto. From the perspective of saving heavy metal materials, on the one hand, the spin orbit moment providing line 10 adopts a multi-segment structure in the horizontal direction, and the position overlapping with MTJ20 is heavy metal materials, including platinum (Pt), tantalum (Ta), tungsten ( Any one of W), iridium (Ir), hafnium (Hf), ruthenium (Ru), thallium (Tl), bismuth (Bi), gold (Au), titanium (Ti) and osmium (Os), other positions It is a metal material with low resistivity, such as copper (Cu), aluminum (Al), and tungsten (W), but is not limited thereto. On the other hand, the spin orbit moment providing line 10 adopts a multilayer structure in the vertical direction, in which the layer in contact with the MTJ20 is made of heavy metal materials, including platinum (Pt), tantalum (Ta), tungsten (W), iridium (Ir ), hafnium (Hf), ruthenium (Ru), thallium (Tl), bismuth (Bi), gold (Au), titanium (Ti) and osmium (Os), the other layers are relatively high resistance materials, For example, one of titanium (Ti), tantalum (Ta), and β-phase-tungsten (W) makes the current tend to flow horizontally through the spin-orbit moment supply line.

On the basis of the magnetic storage device based on the spin orbital moment of the above embodiment, an embodiment of the present invention provides a SOT-MRAM memory cell. Referring to FIG. 3, the magnetic memory device based on the spin orbital moment 100 and a first transistor are provided. M1 and the second transistor M2, where the first transistor M1 is used to control the read operation, and the second transistor M2 is used to control the write operation,

In this embodiment, the fixed layer side of the MTJ20 is connected to the bit line BL through the top electrode, the conductive hole 40 in the dielectric layer 30 is electrically connected to the outside through the metal interconnection structure, and the conductive hole 40 is connected to the first transistor M1 through the metal interconnection structure The gate of M1 is connected to the read word line RWL, and the source of M1 is connected to the source line SL; the end of the spin orbit moment supply line 10 in the horizontal direction away from MTJ20 is connected to the drain of the second transistor M2 , The gate of M2 is connected to the word line WWL, and the source of M2 is connected to the source line SL.

When the SOT-MRAM memory cell shown in Figure 3 reads data, RWL pressurizes M1 to turn on, WWL floats to turn M2 off, BL applies read voltage Vr, SL is grounded, read current passes through MTJ20 and vertically passes through the spin The orbital moment supply line 10 then enters the conductive hole 40, and further passes through M1 to SL to read the resistance of the MTJ and obtain information. During the entire reading process, no horizontal read current passes through the spin-orbit moment supply line 10, which effectively reduces the disturbance of the MTJ free layer caused by the spin-orbit coupling.

The process of writing to the SOT-MRAM memory cell shown in FIG. 3 is further introduced. When writing the first state, WWL pressurizes to turn on M2, RWL floats to turn off M1, a write voltage (+Vw1) is applied to BL, and the write current enters the spin orbit moment supply line 10 through MTJ20 and flows horizontally through the self The orbital moment providing line 10 passes through M2 to the source line SL. After setting this writing process, the MTJ state is the first state.

When writing the second state, WWL pressurizes to turn on M2, RWL floats to turn off M1, a write voltage (-Vw2) is applied to BL, and the write current flows from the source line SL and flows horizontally through the spin track after M2. Moment provides line 10, then enters MTJ20, and finally to bit line BL. After setting this writing process, the MTJ state is the second state.

When realizing the writing process, whether it is writing the first state or writing the second state, the MTJ free layer realizes the reversal of the magnetization direction under the combined action of the STT and SOT effects. Due to the combined action of the STT and SOT effects, the write current will be significant reduce.

Another embodiment of the present invention provides a SOT-MRAM memory cell, as shown in FIG. 4, comprising a spin-orbital moment-based magnetic memory 200, a third transistor M3 and a bidirectional controllable switching device Q1, wherein the third transistor M3 is used to control read and write operations, and the bidirectional controllable switching device Q1 is used to form a current path for write operations,

In this embodiment, the fixed layer side of the MTJ 20 is connected to the bit line BL through the top electrode, the conductive hole 40 in the dielectric layer 30 is electrically connected to the outside through the metal interconnection structure, and the conductive hole 40 is connected to the third transistor M3 through the metal interconnection structure. The drain of the spin-orbital moment supply line 10 is connected to the end of Q1 in the horizontal direction away from MTJ20, the other end of Q1 is connected to the drain of the third transistor M3, and the gate of M3 is connected to the word line WL, M3 The source is connected to the source line SL.

Specifically, the bidirectional controllable switch device Q1 satisfies the following characteristics: the turn-on threshold voltage of Q1 is higher than the read voltage but lower than the write voltage, that is, during a read operation, Q1 is off, and during a write operation, Q1 is on, and When turned on, the on-resistance of the bidirectional controllable switch device Q1 is very small. Q1 can be a bidirectional conduction tube made of materials such as CuGeSe or HfO, and the turn-on threshold voltage is between 0.05V-1V.

When the memory cell shown in Figure 4 reads data, WL pressurizes to turn on M3, BL applies a read voltage Vr, Vr is less than the conduction voltage of the bidirectional controllable switching device Q1, SL is grounded, and the read current passes through MTJ20 and vertically passes through The spin-orbit moment providing wire 10 then enters the conductive hole 40 and further passes through M3 to SL. During the reading process, no horizontal read current passes through the spin-orbit moment supply line 10, which effectively reduces the disturbance of the MTJ free layer caused by the spin-orbit coupling.

Let me introduce the process of writing to the memory cell shown in FIG. 4. When writing the first state, WL pressurizes to make M3 turn on, and a write voltage (+Vw3) is applied to BL. Vw3 is greater than the turn-on voltage of the bidirectional controllable switching device Q1, Q1 turns on, and the conductive hole 40 is equivalent to a via The resistance, the via resistance and the bidirectional controllable switching device Q1 are connected in parallel with the spin-orbit moment supply line 10 and the drain of the third transistor M3. Compared with the on-resistance of Q1, the via resistance is in a high resistance state. Therefore, the write current enters the spin orbit moment supply line 10 through the MTJ20, and then most of the write current level flows through the spin orbit moment supply line 10, flows into the source line SL through Q1 and M3, and only a small part of the write current flows through the conductive hole 40 , M3 flows into the source line SL. After setting this writing process, the MTJ state is the first state.

When writing the second state, WL pressurizes to turn on M3, and a write voltage (-Vw4) is applied to BL. Vw4 is greater than the turn-on voltage of the bidirectional controllable switch device Q1, Q1 turns on, and the write current flows from the source line SL. After M3, since the conductive hole 40 is of high resistance, most of the write current flows through Q1 and horizontally through the spin orbit moment supply line 10, then enters the MTJ20, and finally reaches the bit line BL. Only a small part of the write current flows into the conductive hole 40 and finally reaches the bit line BL through the MTJ 20. After setting this writing process, the MTJ state is the second state.

When realizing the writing process, whether it is writing the first state or writing the second state, the MTJ free layer realizes the reversal of the magnetization direction under the combined action of the STT and SOT effects. Due to the combined action of the STT and SOT effects, the write current will be significant reduce.

It can be seen from the above that in the SOT-MRAM memory cell of the embodiment of the present invention, in the process of realizing read, the read current flows through the vertical conductive path formed by the conductive hole, instead of passing through the spin orbit moment supply line in the horizontal direction. It is in the vertical direction, and the spin-orbital moment provides no read current flowing in the horizontal direction in the line, thereby reducing the read current disturbance of the MTJ caused by the SOT effect and reducing the read error rate of the device. Further, the write operation realizes the reversal of the magnetization direction under the combined action of the STT and SOT effects, which can reduce the write current.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. All should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (10)

A magnetic storage device based on a spin-orbit moment, which is characterized by comprising: a spin-orbit moment supply line, a magnetic tunnel junction located on one side surface of the spin-orbit moment supply line, and a spin-orbit moment supply line. The dielectric layer on the other side of the line, where A side of the free layer of the magnetic tunnel junction is close to the spin-orbit moment providing line, and the horizontal length of the spin-orbit moment providing line is greater than the characteristic length of the magnetic tunnel junction; The dielectric layer is provided with a conductive hole passing through the dielectric layer in a vertical direction, and the position of the conductive hole in the horizontal direction corresponds to the position of the magnetic tunnel junction, and is used to provide a hole perpendicular to the spin The orbital moment provides the conductive path of the wire. The magnetic storage device based on the spin-orbit moment according to claim 1, wherein the conductive holes are made of high-resistivity materials, including titanium (Ti), tantalum (Ta) and β-phase-tungsten (W). Kind of. The magnetic storage device based on the spin orbital moment of claim 1, wherein the conductive hole has a multilayer structure, and a layer of material that is in line contact with the spin orbital moment is a high-resistivity material , Including one of titanium (Ti), tantalum (Ta) and β phase-tungsten (W). The magnetic storage device based on spin orbit moment according to claim 1, wherein the material of the spin orbit moment providing line is a heavy metal material, including platinum (Pt), tantalum (Ta), and tungsten (W) , Iridium (Ir), hafnium (Hf), ruthenium (Ru), thallium (Tl), bismuth (Bi), gold (Au), titanium (Ti), and osmium (Os). The magnetic storage device based on the spin orbit moment according to claim 1, wherein the spin orbit moment supply line adopts a multi-segment structure in the horizontal direction, wherein a position overlapping with the magnetic tunnel junction is a heavy metal Materials, including platinum (Pt), tantalum (Ta), tungsten (W), iridium (Ir), hafnium (Hf), ruthenium (Ru), thallium (Tl), bismuth (Bi), gold (Au), titanium ( Any one of Ti) and Osmium (Os). The magnetic storage device based on the spin orbit moment according to claim 1, wherein the spin orbit moment supply line adopts a multilayer structure in a vertical direction, wherein the layer in contact with the magnetic tunnel junction is Heavy metal materials, including platinum (Pt), tantalum (Ta), tungsten (W), iridium (Ir), hafnium (Hf), ruthenium (Ru), thallium (Tl), bismuth (Bi), gold (Au), titanium Either (Ti) or osmium (Os). A SOT-MRAM memory cell, characterized by comprising the spin-orbital moment-based magnetic memory device according to any one of claims 1 to 6, and further comprising: a first transistor and a second transistor, wherein the first transistor The transistor is used to control the read operation, and the second transistor is used to control the write operation; One side of the fixed layer of the magnetic tunnel junction is connected to a bit line, the conductive hole is connected to the drain of the first transistor, the gate of the first transistor is connected to the read word line, and the The source is connected to the source line; The end of the spin-orbit moment providing line in the horizontal direction away from the magnetic tunnel junction is connected to the drain of the second transistor, the gate of the second transistor is connected to the writing line, and the source of the second transistor The pole is connected to the source line. A SOT-MRAM memory cell, characterized by comprising the spin-orbit moment-based magnetic memory device according to any one of claims 1 to 6, and further comprising: a third transistor and a bidirectional controllable switching device, wherein , The third transistor is used to control the read operation and the write operation, and the bidirectional controllable switch device is used to form a current path for the write operation; One side of the fixed layer of the magnetic tunnel junction is connected to a bit line, the conductive hole is connected to the drain of the third transistor, and the end of the spin-orbit moment providing line in the horizontal direction away from the magnetic tunnel junction passes through The bidirectional controllable switch device is connected to the drain of the third transistor, the gate of the third transistor is connected to the word line, and the source of the third transistor is connected to the source line. 8. The SOT-MRAM memory cell according to claim 8, wherein the bidirectional controllable switch device is a bidirectional conduction transistor made of CuGeSe or HfO. 9. The SOT-MRAM memory cell of claim 9, wherein the turn-on threshold voltage of the bidirectional conduction transistor is between 0.05V and 1V.

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