Magnetic random access memory unit, memory and data writing method

Abstract

The present invention discloses a magnetic random access memory cell, a memory, and a data writing method. The magnetic random access memory cell includes a spin-orbit coupling layer, multiple magnetic tunnel junctions disposed on the spin-orbit coupling layer, and a VCMA control module. The multiple magnetic tunnel junctions include at least a first magnetic tunnel junction and a second magnetic tunnel junction, wherein the cross-sectional dimension of the first magnetic tunnel junction in contact with the spin-orbit coupling layer is larger than the cross-sectional dimension of the second magnetic tunnel junction in contact with the spin-orbit coupling layer. The spin-orbit coupling layer includes a first region where the first magnetic tunnel junction is disposed and a second region where the second magnetic tunnel junction is disposed, wherein the cross-sectional area of ​​the first region for input current is larger than the cross-sectional area of ​​the second region for input current. The present invention can reduce the bit error rate of the magnetic random access memory cell write operation and improve the storage density of the memory cell.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and more particularly to a magnetic random access memory unit, a memory, and a data writing method. Background Art

[0002] As semiconductor process geometries continue to shrink, Moore's Law slows, and increased leakage current and interconnect delays become bottlenecks for traditional CMOS memory. Magnetic random access memory (MRAM), with its advantages of rewritability, non-volatility, fast read / write speeds, and radiation resistance, holds promise as a universal memory and is an ideal device for building next-generation non-volatile main memory and cache. The magnetic tunnel junction is the fundamental storage unit of MRAM. Second-generation spin-transfer torque magnetic random access memory (STT-MRAM) suffers from drawbacks such as long incubation times and read / write interference, limiting its further development. Spin-orbit torque magnetic random access memory (SOT-MRAM) has attracted widespread attention from both industry and academia due to its advantages such as fast write speeds, separate read / write paths, and low power consumption.

[0003] Currently, spin-orbit torque (SOT)-MRAM, based on spin-orbit torque (SOT), is expected to become a core component in the next generation of MRAM write technology. Compared to STT-MRAM, SOT-MRAM write current flows through the underlying spin-orbit coupling layer, avoiding the risk of breakdown. Furthermore, SOT-MRAM theoretically has an ultra-fast write speed of less than 1ns, making it promising for cache applications. Furthermore, the heavy metal forming the spin-orbit coupling layer has low resistivity and low power consumption. SOT-MRAM-based memory devices have separate read and write paths, allowing for thicker barrier layers. To increase the storage density of magnetic random access memory cells, existing technologies employ multiple magnetic tunnel junctions (MTJs) within a single cell. However, when data is written to one of these MTJs, other MTJs may also be miswritten, resulting in a high bit error rate for write operations. Summary of the Invention

[0004] One object of the present invention is to provide a magnetic random access memory cell that reduces the bit error rate of a write operation of the magnetic random access memory cell and improves the storage density of the memory cell. Another object of the present invention is to provide a magnetic random access memory. Yet another object of the present invention is to provide a method for writing data into a magnetic random access memory cell.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention discloses a magnetic random access memory cell, comprising a spin-orbit coupling layer, a plurality of magnetic tunnel junctions arranged on the spin-orbit coupling layer, and a VCMA control module;

[0007] The VCMA control module is used to input a VCMA voltage to the corresponding magnetic tunnel junction to change the perpendicular anisotropy state of the magnetic tunnel junction;

[0008] The plurality of magnetic tunnel junctions include at least a first magnetic tunnel junction and a second magnetic tunnel junction, wherein a cross-sectional dimension of the first magnetic tunnel junction in contact with the spin-orbit coupling layer is larger than a cross-sectional dimension of the second magnetic tunnel junction in contact with the spin-orbit coupling layer;

[0009] The spin-orbit coupling layer includes a first region where the first magnetic tunnel junction is arranged and a second region where the second magnetic tunnel junction is arranged, and a cross-sectional area of ​​the first region for inputting current is larger than a cross-sectional area of ​​the second region for inputting current;

[0010] The magnetic random access memory cell further comprises a first write line, a second write line, a write control line, a first control line and a second control line, and the magnetic random access memory cell further comprises a first switching element and a second switching element;

[0011] A first end of the first switching element is connected to the first write line, and a second end is connected to the first input end of the spin-orbit coupling layer;

[0012] A first end of the second switch element is connected to the second write line, and a second end is connected to the second input end of the spin-orbit coupling layer;

[0013] The control ends of the first switching element and the second switching element are connected to the write control line;

[0014] The first control line and the second control line are connected to the top of the first magnetic tunnel junction and the second magnetic tunnel junction, respectively.

[0015] Optionally, the VCMA control module is configured to input a VCMA voltage to the corresponding magnetic tunnel junction so that the first magnetic tunnel junction is in a first perpendicular anisotropy state, and the second magnetic tunnel junction is in a second perpendicular anisotropy state, wherein the perpendicular anisotropy of the first perpendicular anisotropy state is greater than the perpendicular anisotropy of the second perpendicular anisotropy state;

[0016] When the VCMA control module inputs a low-level VCMA voltage to the first magnetic tunnel junction, the critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value; when the VCMA control module inputs a high-level VCMA voltage to the first magnetic tunnel junction, the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value;

[0017] When the VCMA control module inputs a low-level VCMA voltage to the second magnetic tunnel junction, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a third critical current value; when the VCMA control module inputs a high-level VCMA voltage to the second magnetic tunnel junction, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value;

[0018] The first critical current value is greater than the second critical current value; the third critical current value is greater than the fourth critical current value.

[0019] Optionally, the first critical current value is greater than the fourth critical current value; and the third critical current value is greater than the second critical current value.

[0020] Optionally, the first magnetic tunnel junction and the second magnetic tunnel junction include a fixed layer, a barrier layer and a free layer arranged in sequence from top to bottom;

[0021] The bottom surfaces of the free layers of the first magnetic tunnel junction and the second magnetic tunnel junction are fixedly connected to the spin-orbit coupling layer.

[0022] Optionally, the critical switching current of the first magnetic tunnel junction free layer is a first current threshold, the critical switching current of the second magnetic tunnel junction free layer is a second current threshold, and the first current threshold is greater than the second current threshold;

[0023] When the current density of the spin-orbit torque current inputted by the spin-orbit coupling layer is greater than a first current threshold, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction change deterministically;

[0024] When the spin-orbit torque current inputted by the spin-orbit coupling layer is between a first current threshold and a second current threshold, the resistance state of the first magnetic tunnel junction remains unchanged, and the resistance state of the second magnetic tunnel junction changes deterministically;

[0025] When the spin-orbit torque current inputted by the spin-orbit coupling layer is less than a second current threshold, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction remain unchanged.

[0026] Optionally, it further includes a third switch element and a read control line;

[0027] The first end and the second end of the third switch element are connected to the first control line and the second control line respectively, and the control end of the third switch element is connected to the read control line.

[0028] The present invention also discloses a magnetic random access memory, comprising a plurality of magnetic random access memory units as described above arranged in an array.

[0029] The present invention also discloses a method for writing data into a magnetic random access memory cell, comprising:

[0030] Determining a spin-orbit torque current based on data to be written and inputting the spin-orbit torque current into the spin-orbit coupling layer, wherein if the data to be written is “00”, the spin-orbit torque current is a write current in a first direction, and a current density of the write current is greater than a critical switching current of the first magnetic tunnel junction;

[0031] If the data to be written is "01", the spin-orbit torque current includes a first write current in a first direction and a second write current in a second direction input sequentially, a current density of the first write current is greater than a critical switching current of the first magnetic tunnel junction, and a current density of the second write current is greater than a critical switching current of the second magnetic tunnel junction and less than a critical switching current of the first magnetic tunnel junction;

[0032] If the data to be written is “10”, the spin-orbit torque current includes a first write current in a second direction and a second write current in a first direction input sequentially, a current density of the first write current is greater than a critical switching current of the first magnetic tunnel junction, and a current density of the second write current is greater than a critical switching current of the second magnetic tunnel junction and less than a critical switching current of the first magnetic tunnel junction;

[0033] If the data to be written is "11", the spin-orbit torque current is a write current in the second direction, and the current density of the write current is greater than the critical switching current of the first magnetic tunnel junction.

[0034] Optionally, when writing "00", a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the write current in the first direction is greater than the second critical current value;

[0035] When "01" is written, a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the first write current in the first direction is greater than the second critical current value; a low-level VCMA voltage is input to the first magnetic tunnel junction, and a high-level VCMA voltage is input to the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the first write current in the first direction is greater than the fourth critical current value and less than the first critical current value;

[0036] When "10" is written, a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the first write current in the second direction is greater than the second critical current value; a low-level VCMA voltage is input to the first magnetic tunnel junction, and a high-level VCMA voltage is input to the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the second write current in the first direction is greater than the fourth critical current value and less than the first critical current value;

[0037] When "11" is written, a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical flipping current for flipping the free layer of the first magnetic tunnel junction is the second critical current value, the critical flipping current for flipping the free layer of the second magnetic tunnel junction is the fourth critical current value, and the current density of the write current in the second direction is greater than the second critical current value.

[0038] Optionally, determining the spin-orbit torque current input to the spin-orbit coupling layer based on the data to be written includes:

[0039] reading the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction;

[0040] determining whether the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction need to be changed according to the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction and the data to be written;

[0041] When data "0" is input only to the first magnetic tunnel junction, a high-level VCMA voltage is input to the first magnetic tunnel junction, and a low-level VCMA voltage is input to the second magnetic tunnel junction, so that a critical switching current for switching the free layer of the first magnetic tunnel junction is a second critical current value, a critical switching current for switching the free layer of the second magnetic tunnel junction is a third critical current value, and a current density of a write current in the first direction is greater than the second critical current value and less than the third critical current value;

[0042] When data "1" is input only to the first magnetic tunnel junction, a high-level VCMA voltage is input to the first magnetic tunnel junction, and a low-level VCMA voltage is input to the second magnetic tunnel junction, so that a critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, a critical switching current for flipping the free layer of the second magnetic tunnel junction is a third critical current value, and a current density of a write current in the second direction is greater than the second critical current value and less than the third critical current value;

[0043] When data "1" is input only to the second magnetic tunnel junction, a low-level VCMA voltage is input to the first magnetic tunnel junction, a high-level VCMA voltage is input to the second magnetic tunnel junction, a critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, a critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and a current density of a write current in the first direction is greater than the fourth critical current value and less than the first critical current value;

[0044] When only data "0" is input to the second magnetic tunnel junction, a low-level VCMA voltage is input to the first magnetic tunnel junction, and a high-level VCMA voltage is input to the second magnetic tunnel junction, so that the critical flipping current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, the critical flipping current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the write current in the second direction is greater than the fourth critical current value and less than the first critical current value.

[0045] The beneficial effects of the present invention are as follows:

[0046] The magnetic random access memory cell of the present invention comprises at least a first magnetic tunnel junction and a second magnetic tunnel junction on a spin-orbit coupling layer. The cross-sectional dimensions of the first magnetic tunnel junction and the cross-sectional area of ​​the input current of the spin-orbit coupling layer are made larger than those of the second magnetic tunnel junction. This dual structure significantly increases the difference in critical switching current between the free layers of the first and second magnetic tunnel junctions, thereby reducing the error rate during data writing. Furthermore, the present invention utilizes a VCMA control module to separately regulate the perpendicular anisotropy states of the first and second magnetic tunnel junctions, thereby further adjusting the critical switching currents of the free layers of the first and second magnetic tunnel junctions as needed for data writing, thereby achieving accurate data writing and reducing the bit error rate of data writing. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0048] Figure 1 A schematic structural diagram showing a specific embodiment of a magnetic random access memory cell according to the present invention is shown;

[0049] Figure 2 A schematic diagram showing a write path of a magnetic random access memory cell according to a specific embodiment of the present invention is shown;

[0050] Figure 3 A schematic diagram showing a read path of a magnetic random access memory cell according to a specific embodiment of the present invention;

[0051] Figure 4 A schematic diagram showing a specific example of a magnetic random access memory of the present invention;

[0052] Figure 5 A schematic diagram showing correspondence between written data and signals in a specific embodiment of a magnetic random access memory cell according to the present invention;

[0053] Figure 6 A schematic structural diagram of a computer device including the magnetic random access memory of the present invention is shown. DETAILED DESCRIPTION

[0054] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the following detailed description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0055] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; they may refer to direct connection or indirect connection through an intermediate medium; they may refer to internal communication between two elements or interaction between two elements. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0056] In the present invention, unless otherwise clearly stipulated and limited, the first feature being "on" or "under" the second feature may include the first and second features being in direct contact, or the first and second features not being in direct contact but being in contact through another feature between them.

[0057] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are used to refer to positions or locations based on those shown in the accompanying drawings. These terms are intended solely to facilitate description and simplify operation, and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meaning.

[0058] According to one aspect of the present invention, this embodiment discloses a magnetic random access memory cell. Figure 1-Figure 3As shown, in this embodiment, the magnetic random access memory unit includes a spin-orbit coupling layer 1, a plurality of magnetic tunnel junctions arranged on the spin-orbit coupling layer 1, and a VCMA control module.

[0059] The VCMA control module is used to input a VCMA voltage to the corresponding magnetic tunnel junction to change the perpendicular anisotropy state of the magnetic tunnel junction.

[0060] The multiple magnetic tunnel junctions include at least a first magnetic tunnel junction MTJ1 and a second magnetic tunnel junction MTJ2, wherein the cross-sectional size of the first magnetic tunnel junction MTJ1 in contact with the spin-orbit coupling layer 1 is larger than the cross-sectional size of the second magnetic tunnel junction MTJ2 in contact with the spin-orbit coupling layer 1.

[0061] The spin-orbit coupling layer 1 includes a first region where the first magnetic tunnel junction MTJ1 is set and a second region where the second magnetic tunnel junction MTJ2 is set. The cross-sectional area of ​​the first region for inputting current is larger than the cross-sectional area of ​​the second region for inputting current.

[0062] The magnetic random access memory further includes a first write line SL1, a second write line SL2, a write control line WL, a first control line BL1 and a second control line BL2. The magnetic random access memory cell further includes a first switch element N1 and a second switch element N2.

[0063] A first end of the first switch element N1 is connected to the first write line SL1 , and a second end of the first switch element N1 is connected to the first input end of the spin-orbit coupling layer 1 .

[0064] A first end of the second switch element N2 is connected to the second write line SL2 , and a second end of the second switch element N2 is connected to the second input end of the spin-orbit coupling layer 1 .

[0065] The control terminals of the first switch element N1 and the second switch element N2 are connected to the write control line WL;

[0066] The first control line BL1 and the second control line BL2 are connected to the top of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2, respectively.

[0067] By controlling the first and second switching elements N1 and N2 to conduct via the write control line WL, the first and second write lines SL1 and SL2 are connected to the corresponding memory cell to form a loop, inputting an SOT current into the memory cell's spin-orbit coupling layer 1, thereby implementing the data writing function. Simultaneously, via the first and second control lines BL1 and BL2 connected to the top of the magnetic tunnel junction, a VCMA voltage can be input to control the magnetic tunnel junction for data writing, assisting in achieving deterministic data writing. In the present invention, each magnetic random access memory cell only requires the first and second switching elements N1 and N2 to control writing.

[0068] Optionally, input electrodes 6 can be set at both ends of the spin-orbit coupling layer 1 of the magnetic random access memory unit, which are electrically connected to the switching element through the input electrodes 6, and a top electrode 5 can be set on the top of the magnetic tunnel junction to be electrically connected to the first control line BL1 or the second control line BL2.

[0069] The magnetic random access memory cell of the present invention is provided with at least a first magnetic tunnel junction MTJ1 and a second magnetic tunnel junction MTJ2 on a spin-orbit coupling layer 1, so that the cross-sectional dimensions of the first magnetic tunnel junction MTJ1 and the cross-sectional area of ​​the input current of the spin-orbit coupling layer 1 are larger than those of the second magnetic tunnel junction MTJ2. This double structure increases the difference in the critical flip current of the free layer 2 of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2, thereby reducing the error rate during data writing. In addition, the present invention also adjusts the perpendicular anisotropy state of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 respectively through a VCMA control module to further adjust the critical flip current of the free layer 2 of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 according to the needs of writing data, thereby achieving accurate data writing and reducing the bit error rate of data writing.

[0070] Furthermore, in the prior art, for a memory cell with multiple MTJs on a spin-orbit coupling layer, the writing and reading of each magnetic tunnel junction requires setting a control transistor at the top of each MTJ to avoid the mutual influence of data writing and reading between different MTJs, but this cell structure requires more transistors. In the memory cell of the present application, the cross-sectional dimensions of the first magnetic tunnel junction and the second magnetic tunnel junction and the cross-sectional areas of the first region and the second region are different. Through this structural design, the difference in critical current for magnetic moment reversal of the first magnetic tunnel junction and the second magnetic tunnel junction is larger. The top of the MTJ can be directly connected to the control line of the input VCMA voltage, and the top of the MTJ does not need to be provided with a switching element such as a transistor. The writing and reading of data from different MTJs will not affect each other, and there is no need to consider the influence of the voltage drop of the switching element on the voltage. At the same time, there will be no situation where the VCMA voltage damages the switching element. Moreover, the memory cell of the present application only requires two switching devices to control the deterministic writing of data of multiple magnetic tunnel junctions in the cell, which reduces the number of switching devices, saves the cell area, and effectively increases the storage density.

[0071] In an optional embodiment, the VCMA control module is used to input a VCMA voltage to the corresponding magnetic tunnel junction so that the first magnetic tunnel junction MTJ1 is in a first perpendicular anisotropy state, and the second magnetic tunnel junction MTJ2 is in a second perpendicular anisotropy state, and the perpendicular anisotropy of the first perpendicular anisotropy state is greater than the perpendicular anisotropy of the second perpendicular anisotropy state.

[0072] Specifically, it can be understood that the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 of the present invention have perpendicular magnetic anisotropy (PMA). The VCMA control module can change the PMA phenomenon of the magnetic layer of the magnetic tunnel junction (MTJ) by applying an external VCMA voltage to the MTJ. Changes in PMA affect the critical switching conditions of the MTJ. By applying a VCMA voltage to the top of the MTJ, the VCMA effect changes the PMA of the MTJ, weakening the stability of the free layer 2, making it easier to switch, and reducing the critical switching current density of the MTJ.

[0073] Therefore, the present invention sets the cross-sectional area of ​​the first magnetic tunnel junction MTJ1 in contact with the spin-orbit coupling layer 1 to be larger than the cross-sectional area of ​​the second magnetic tunnel junction MTJ2 in contact with the spin-orbit coupling layer 1, so that the resistance of the second magnetic tunnel junction MTJ2 in the corresponding blocking state is greater than that of the first magnetic tunnel junction MTJ1. In addition, the cross-sectional area of ​​the spin-orbit coupling layer 1 of the first magnetic tunnel junction MTJ1 is larger than the cross-sectional area of ​​the spin-orbit coupling layer 1 of the second magnetic tunnel junction MTJ2. That is, at the same thickness, the width of the spin-orbit coupling layer 1 of the first magnetic tunnel junction MTJ1 is larger than the width of the spin-orbit coupling layer 1 of the second magnetic tunnel junction MTJ2. When the SOT current flows through the spin-orbit coupling layer 1, the current density in the spin-orbit coupling layer 1 at the bottom of the first magnetic tunnel junction MTJ1 is smaller, and the critical switching current difference between the two MTJs is further widened. Among them, the VCMA control module applies a VCMA voltage to the two MTJs so that the perpendicular anisotropy of the first perpendicular anisotropy state is greater than the perpendicular anisotropy of the second perpendicular anisotropy state, further increasing the current density difference between the critical switching currents of the two MTJs. Through the above setting, the critical switching current required by the first magnetic tunnel junction MTJ1 is much greater than that of the second magnetic tunnel junction MTJ2, thereby improving the reliability of data writing and reducing the write bit error rate.

[0074] In an optional embodiment, when the VCMA control module inputs a low-level VCMA voltage to the first magnetic tunnel junction MTJ1, the critical flipping current for flipping the free layer of the first magnetic tunnel junction MTJ1 is a first current value, and when the low-level VCMA voltage is input to the second magnetic tunnel junction MTJ2, the critical flipping current for flipping the free layer of the second magnetic tunnel junction MTJ2 is a second current value, and the first current value is greater than the second current value;

[0075] When the VCMA control module inputs a high-level VCMA voltage to the first magnetic tunnel junction MTJ1, the critical flipping current for flipping the free layer of the first magnetic tunnel junction MTJ1 is a third current value; when a high-level VCMA voltage is input to the second magnetic tunnel junction MTJ2, the critical flipping current for flipping the free layer of the second magnetic tunnel junction MTJ2 is a fourth current value, and the third critical current value is greater than the fourth critical current value.

[0076] Specifically, the VCMA control module adjusts the perpendicular anisotropy state of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 by ​​applying a high level or a low level to the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2, and at the same time adjusts the size of the SOT current to achieve the change of the corresponding resistance state of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2, so as to achieve the purpose of writing specific data.

[0077] Preferably, the first critical current value is greater than the fourth critical current value; and the third critical current value is greater than the second critical current value.

[0078] In an optional embodiment, when the VCMA control module inputs a low-level VCMA voltage to the first magnetic tunnel junction MTJ1 and inputs a low-level VCMA voltage to the second magnetic tunnel junction MTJ2, the critical flipping current for flipping the free layer of the first magnetic tunnel junction MTJ1 is a first current value, and the critical flipping current for flipping the free layer of the second magnetic tunnel junction MTJ2 is a second current value, and the first current value is greater than the second current value; when the spin-orbit torque current input by the spin-orbit coupling layer is greater than the first current value, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction change deterministically; when the spin-orbit torque current input by the spin-orbit coupling layer is between the first current value and the second current value, the resistance state of the first magnetic tunnel junction remains unchanged, and the resistance state of the second magnetic tunnel junction changes deterministically; when the spin-orbit torque current input by the spin-orbit coupling layer is less than the second current value, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction remain unchanged.

[0079] In another optional embodiment, when the VCMA control module inputs a high-level VCMA voltage to the first magnetic tunnel junction MTJ1 and a low-level VCMA voltage to the second magnetic tunnel junction MTJ2, the critical flipping current for flipping the free layer of the first magnetic tunnel junction MTJ1 is a third current value, and the critical flipping current for flipping the free layer of the second magnetic tunnel junction MTJ2 is a second current value. If the third current value is greater than the second current value; when the spin-orbit torque current input by the spin-orbit coupling layer is greater than the third current value, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction change deterministically; when the spin-orbit torque current input by the spin-orbit coupling layer is between the third current value and the second current value, the resistance state of the first magnetic tunnel junction remains unchanged, and the resistance state of the second magnetic tunnel junction changes deterministically; when the spin-orbit torque current input by the spin-orbit coupling layer is less than the second current value, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction remain unchanged. On the contrary, if the third current value is less than the second current value; when the spin-orbit torque current input by the spin-orbit coupling layer is greater than the second current value, the resistance state of the first magnetic tunnel junction and the second magnetic tunnel junction changes deterministically; when the spin-orbit torque current input by the spin-orbit coupling layer is between the third current value and the second current value, the resistance state of the first magnetic tunnel junction changes deterministically, and the resistance state of the second magnetic tunnel junction remains unchanged; when the spin-orbit torque current input by the spin-orbit coupling layer is less than the third current value, the resistance state of the first magnetic tunnel junction and the second magnetic tunnel junction remains unchanged.

[0080] In another optional embodiment, when the VCMA control module inputs a low-level VCMA voltage to the first magnetic tunnel junction MTJ1 and a high-level VCMA voltage to the second magnetic tunnel junction MTJ2, the critical flipping current for flipping the free layer of the first magnetic tunnel junction MTJ1 is a first current value, and the critical flipping current for flipping the free layer of the second magnetic tunnel junction MTJ2 is a fourth current value, and the first current value is greater than the fourth current value; when the spin-orbit torque current input by the spin-orbit coupling layer is greater than the first current value, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction change deterministically; when the spin-orbit torque current input by the spin-orbit coupling layer is between the first current value and the fourth current value, the resistance state of the first magnetic tunnel junction remains unchanged, and the resistance state of the second magnetic tunnel junction changes deterministically; when the spin-orbit torque current input by the spin-orbit coupling layer is less than the fourth current value, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction remain unchanged. In this embodiment, the critical flip currents of the first magnetic tunnel junction and the second magnetic tunnel junction are the first current value and the fourth current value, respectively. The difference between the first current value and the fourth current value is larger than the difference between the first current value and the second current value, and the current margin is larger, thereby effectively reducing the possibility of erroneous writing and improving device reliability.

[0081] In another optional embodiment, when the VCMA control module inputs a high-level VCMA voltage to the first magnetic tunnel junction MTJ1 and inputs a high-level VCMA voltage to the second magnetic tunnel junction MTJ2, the critical flipping current for flipping the free layer of the first magnetic tunnel junction MTJ1 is a third current value, and the critical flipping current for flipping the free layer of the second magnetic tunnel junction MTJ2 is a fourth current value, and the third current value is greater than the fourth current value; when the spin-orbit torque current input by the spin-orbit coupling layer is greater than the third current value, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction change deterministically; when the spin-orbit torque current input by the spin-orbit coupling layer is between the third current value and the fourth current value, the resistance state of the first magnetic tunnel junction remains unchanged, and the resistance state of the second magnetic tunnel junction changes deterministically; when the spin-orbit torque current input by the spin-orbit coupling layer is less than the fourth current value, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction remain unchanged.

[0082] Therefore, it should be noted that the adjustment method of the VCMA control module on the perpendicular anisotropy state of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 and the specific structure of the VCMA control module can be set by those skilled in the art according to actual needs. The present invention is not limited to this, and other technical solutions based on the same inventive concept should also be within the scope of protection of the present invention.

[0083] In an optional embodiment, the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 include a fixed layer 4, a barrier layer 3 and a free layer 2 arranged in sequence from top to bottom.

[0084] The bottom surfaces of the free layers 2 of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 are fixedly connected to the spin-orbit coupling layer 1 .

[0085] Specifically, the magnetic tunnel junction may include a fixed layer 4, a barrier layer 3, and a free layer 2 arranged in sequence from top to bottom. The bottom surface of the free layer 2 is fixedly connected to the spin-orbit coupling layer 1. It can be understood that the resistance of the magnetic tunnel junction depends on the magnetization direction of the fixed layer 4 and the free layer 2, and the magnetization direction of the free layer 2 and the fixed layer 4 is determined by the direction of the magnetic moment, and the reversal of the magnetic moment direction depends on the SOT current input by the spin-orbit coupling layer 1. If the SOT current is greater than the critical reversal current of the free layer 2, the magnetic moment direction of the free layer 2 undergoes a deterministic reversal corresponding to the SOT current. Therefore, by controlling the magnitude of the SOT current, the magnetic moment direction of the free layer 2 of the magnetic tunnel junction can be controlled to control the resistance state change of the magnetic tunnel junction.

[0086] When the magnetic moments of the pinned layer 4 and the free layer 2 are aligned, the magnetic tunnel junction is in a low-resistance state (low-resistance state). When the magnetic moments of the pinned layer 4 and the free layer 2 are aligned, the magnetic tunnel junction is in a high-resistance state (high-resistance state). The high-resistance and low-resistance states of the magnetic tunnel junction can be pre-assigned to different data. For example, the high-resistance state can be pre-assigned to data "1" and the low-resistance state can be pre-assigned to data "0." A read circuit then inputs a current or voltage into the magnetic tunnel junction. The change in current or voltage can be used to determine whether the resistance state of the magnetic tunnel junction is high or low. Based on the resistance state of the magnetic tunnel junction, the data stored in the magnetic tunnel junction can be determined as "1" or "0." Determining the range of the high-resistance and low-resistance states is a common technique in the art. Those skilled in the art can determine the resistance ranges of the high-resistance and low-resistance states of the magnetic tunnel junction based on common knowledge, and this will not be elaborated upon herein.

[0087] In an optional embodiment, when the critical switching current of the free layer 2 of the first magnetic tunnel junction MTJ1 is a first current threshold, the critical switching current of the free layer 2 of the second magnetic tunnel junction MTJ2 is a second current threshold, and the first current threshold is greater than the second current threshold;

[0088] When the current density of the spin-orbit torque current inputted by the spin-orbit coupling layer 1 is greater than a first current threshold, the resistance states of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 are deterministically changed;

[0089] When the spin-orbit torque current inputted by the spin-orbit coupling layer 1 is between a first current threshold and a second current threshold, the resistance state of the first magnetic tunnel junction MTJ1 remains unchanged, and the resistance state of the second magnetic tunnel junction MTJ2 changes deterministically;

[0090] When the spin-orbit torque current input into the spin-orbit coupling layer 1 is less than a second current threshold, the resistance states of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 remain unchanged.

[0091] It can be understood that due to the cross-section of the magnetic tunnel junction free layer 2 and the effect of the VCMA adjustment module, the critical switching current of the free layer 2 of the first magnetic tunnel junction MTJ1 is greater than the critical switching current of the second magnetic tunnel junction MTJ2. Therefore, when the spin-orbit torque current is input into the spin-orbit coupling layer 1, the current density flowing through the first magnetic tunnel junction MTJ1 is smaller than that of the second magnetic tunnel junction MTJ2. The SOT current required for the magnetic moment switching of the free layer 2 of the first magnetic tunnel junction MTJ1 is much larger than the SOT current required for the magnetic moment switching of the free layer 2 of the second magnetic tunnel junction MTJ2. The current margin for writing data with different magnetic tunnel strengths becomes larger, thereby improving the accuracy of written data and reducing the bit error rate.

[0092] When writing, Figure 2 As shown, Figure 2 In the figure, the dotted lines indicate the flow of the write current Iwrite. The first and second control lines BL1 and BL2 provide voltages BL1 and BL2 to MTJ1 and MTJ2, respectively, through the top electrode 5 of the MTJ (BL2 = VH, BL1 = GND). This increases the critical switching current density of MTJ1 to a greater value than that of MTJ2. Furthermore, due to the different cross-sectional areas of the spin-orbit coupling layer 1, the current density at the bottom of MTJ1 is lower for a given current. By setting the write control line WLWL high, N1 and N2 are turned on, and voltage is applied to BL1, BL2, and SL1, SL2. The write current primarily flows through the two switching elements and the spin-orbit coupling layer 1 at the bottom of the two magnetic tunnel junctions, with a small amount of shunt current flowing through the magnetic tunnel junctions. Because voltage is applied to the top electrode of the magnetic tunnel junction, the MTJ thickness must be increased to prevent breakdown. As a result, the resistance of the magnetic tunnel junction is much greater than the resistance of the spin-orbit coupling layer 1 and the on-resistance of the switching element, making the impact of the shunt current on the write operation negligible.

[0093] In an optional embodiment, the magnetic random access memory cell further includes a third switching element and a read control line.

[0094] The first end and the second end of the third switch element are connected to the first control line BL1 and the second control line BL2 respectively, and the control end of the third switch element is connected to the read control line REN.

[0095] Specifically, during a read operation, such as Figure 3 As shown, Figure 3 In the figure, the dotted line represents the flow direction of the read current Iread. The high level of WL opens N1 and N2, and the high level of REN shorts BL1 and BL2. The high level of BL1 causes the read current to flow through the two MTJs at the same time. The two MTJs are connected in parallel. The resistance of the MTJ is judged according to the magnitude of the current, and thus the state of the MTJ can be judged.

[0096] The data writing method of the magnetic random access memory cell according to the embodiment of the present application includes:

[0097] Determining a spin-orbit torque current based on data to be written and inputting the spin-orbit torque current into the spin-orbit coupling layer, wherein if the data to be written is “00”, the spin-orbit torque current is a write current in a first direction, and a current density of the write current is greater than a critical switching current of the first magnetic tunnel junction;

[0098] If the data to be written is "01", the spin-orbit torque current includes a first write current in a first direction and a second write current in a second direction input sequentially, a current density of the first write current is greater than a critical switching current of the first magnetic tunnel junction, and a current density of the second write current is greater than a critical switching current of the second magnetic tunnel junction and less than a critical switching current of the first magnetic tunnel junction;

[0099] If the data to be written is “10”, the spin-orbit torque current includes a first write current in a second direction and a second write current in a first direction input sequentially, a current density of the first write current is greater than a critical switching current of the first magnetic tunnel junction, and a current density of the second write current is greater than a critical switching current of the second magnetic tunnel junction and less than a critical switching current of the first magnetic tunnel junction;

[0100] If the data to be written is "11", the spin-orbit torque current is a write current in the second direction, and the current density of the write current is greater than the critical switching current of the first magnetic tunnel junction.

[0101] Specifically, it is understandable that when data is written to the magnetic random access memory cell, different data combinations can be written to the two magnetic tunnel junctions by controlling the VCMA voltage and the magnitude and direction of the write current.

[0102] In a preferred embodiment, when writing "00", a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the write current in the first direction is greater than the second critical current value;

[0103] When "01" is written, a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the first write current in the first direction is greater than the second critical current value; a low-level VCMA voltage is input to the first magnetic tunnel junction, and a high-level VCMA voltage is input to the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the first write current in the first direction is greater than the fourth critical current value and less than the first critical current value;

[0104] When "10" is written, a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the first write current in the second direction is greater than the second critical current value; a low-level VCMA voltage is input to the first magnetic tunnel junction, and a high-level VCMA voltage is input to the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the second write current in the first direction is greater than the fourth critical current value and less than the first critical current value;

[0105] When "11" is written, a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical flipping current for flipping the free layer of the first magnetic tunnel junction is the second critical current value, the critical flipping current for flipping the free layer of the second magnetic tunnel junction is the fourth critical current value, and the current density of the write current in the second direction is greater than the second critical current value.

[0106] In order to improve data writing efficiency and accuracy, it is possible to determine whether the resistance state of the magnetic tunnel junction needs to be changed based on the data to be written. If it needs to be changed, the data is only written to the magnetic tunnel junction where the data is to be written, thereby reducing the number of data writing steps. The method of determining the spin-orbit torque current input to the spin-orbit coupling layer based on the data to be written includes:

[0107] reading the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction;

[0108] determining whether the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction need to be changed according to the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction and the data to be written;

[0109] When data "0" is input only to the first magnetic tunnel junction, a high-level VCMA voltage is input to the first magnetic tunnel junction, and a low-level VCMA voltage is input to the second magnetic tunnel junction, so that a critical switching current for switching the free layer of the first magnetic tunnel junction is a second critical current value, a critical switching current for switching the free layer of the second magnetic tunnel junction is a third critical current value, and a current density of a write current in the first direction is greater than the second critical current value and less than the third critical current value;

[0110] When data "1" is input only to the first magnetic tunnel junction, a high-level VCMA voltage is input to the first magnetic tunnel junction, and a low-level VCMA voltage is input to the second magnetic tunnel junction, so that a critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, a critical switching current for flipping the free layer of the second magnetic tunnel junction is a third critical current value, and a current density of a write current in the second direction is greater than the second critical current value and less than the third critical current value;

[0111] When data "1" is input only to the second magnetic tunnel junction, a low-level VCMA voltage is input to the first magnetic tunnel junction, a high-level VCMA voltage is input to the second magnetic tunnel junction, a critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, a critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and a current density of a write current in the first direction is greater than the fourth critical current value and less than the first critical current value;

[0112] When only data "0" is input to the second magnetic tunnel junction, a low-level VCMA voltage is input to the first magnetic tunnel junction, and a high-level VCMA voltage is input to the second magnetic tunnel junction, so that the critical flipping current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, the critical flipping current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the write current in the second direction is greater than the fourth critical current value and less than the first critical current value.

[0113] In a specific example, Figure 1-Figure 3As shown, assuming that the current from SL1 to SL2 passing through the MTJ1 spin-orbit coupling layer 1 exceeds IC1, the MTJ1 will flip to a parallel state (indicating data 0); the current from SL1 to SL2 passing through the MTJ2 spin-orbit coupling layer 1 exceeds IC2, the MTJ2 will flip to a parallel state (indicating data 0); the current from SL2 to SL1 passing through the MTJ1 spin-orbit coupling layer 1 exceeds IC1, the MTJ1 will flip to an anti-parallel state (indicating data 1); the current from SL2 to SL1 passing through the MTJ2 spin-orbit coupling layer 1 exceeds IC2, the MTJ2 will flip to an anti-parallel state (indicating data 1).

[0114] It is defined that the magnitude of the SOT current IH satisfies IH>IC1>IC2, and the magnitude of the SOT current IL satisfies IC1>IL>IC2.

[0115] If data needs to be written in two MTJs, first set WL to a high level, turn on N1 and N2, connect BL1 to a high level, connect BL2 to a low level, and apply a current of IH. At this time, the same value is written in the two MTJs. If MTJ2 is the same as the target state, the writing is completed; if it is different from the target state, apply a current of IL in the opposite direction to complete the writing of MTJ2.

[0116] If you only need to write in MTJ1, first set WL to a high level, open N1 and N2, connect BL1 to a high level, and connect BL2 to a low level. Apply a current of IH according to the target state, and write the same value to the two MTJs. At this time, if MTJ2 is the same as the initial state, the writing is completed; if it is different from the initial state, apply a current of IL in the opposite direction to write MTJ2 back to the initial state.

[0117] If you only need to write in MTJ2, first set WL to a high level, open N1 and N2, connect BL1 to a high level, connect BL2 to a low level, apply a current of IL according to the target state, and write the required value into MTJ2.

[0118] If the original data in the storage unit is not considered, the general steps for writing four types of data to two MTJs are:

[0119] Step 0: WL is high, N1 and N2 are turned on, BL1 is connected to a high level, and BL2 is connected to a low level.

[0120] Step 1: Select the direction of the applied current according to the desired state of MTJ1. The amplitude of the current is IH, so that the magnetization directions of MTJ1 and MTJ2 are both written to the desired state of MTJ1. If the target states of MTJ1 and MTJ2 are the same, the write operation ends. If the target states of MTJ1 and MTJ2 are different, go to step 2.

[0121] Step 2: Apply a current in the opposite direction to that in step 1, where the current amplitude is IL, so that the magnetization direction of MTJ2 is written to the desired state of MTJ2, and the write operation is completed.

[0122] The specific write operations are:

[0123] Step 0: Set WL to high level, turn on N1 and N2, connect BL1 to high level, and connect BL2 to low level.

[0124] If the data written is 00:

[0125] Step 1: Apply a current from SL1 to SL2 (SL12SL2) with an amplitude of IH, and the data 00 is written, and the write operation is completed.

[0126] If the data written is 01:

[0127] Step 1: Apply a current from SL1 to SL2 (SL12SL2) with an amplitude of IH, data 00 is written, and the write operation continues.

[0128] Step 2: Apply a current from SL2 to SL1 (SL22SL1) with an amplitude of IL, and the data 01 is written, and the write operation is completed.

[0129] If the data written is 11:

[0130] Step 1: Apply a current from SL2 to SL1 (SL22SL1) with an amplitude of IH, and the data 11 is written, and the write operation is completed.

[0131] If the data written is 01:

[0132] Step 1: Apply a current from SL2 to SL1 (SL22SL1) with an amplitude of IH, data 11 is written, and the write operation continues.

[0133] Step 2: Apply a current from SL1 to SL2 (SL12SL2) with an amplitude of IL, and the data 10 is written, and the write operation is completed.

[0134] Considering the original data in the memory cell, the general steps for writing four types of data to two MTJs are:

[0135] Step 0: WL high level turns on N1 and N2, BL1 is connected to high level, and BL2 is connected to low level.

[0136] Step 1: Read the original data in the storage unit. If the data to be written is the same as the original data, the write operation ends; if the data to be written is different from the original data, go to step 2.

[0137] Step 2: WL is high, N1 and N2 are turned on. Figure 5 The state transition diagram shown selects the path with the minimum cost (such as the minimum power consumption and the shortest path) to write data.

[0138] During a read operation:

[0139] Assume that the high and low resistance values ​​of MTJ1 and MTJ2 are as shown in Table 1:

[0140] Table 1

[0141]

[0142] The resistances of the four states of the memory cell are shown in Table 2 from low to high, where (A=1+TMR), and TMR is the magnetoresistance of the magnetic tunnel junction.

[0143] Table 2

[0144]

[0145] In order to improve reading performance and reduce the probability of reading failure, the standard deviation of each data item should be considered when setting the reference resistance. The ideal reference resistance is set according to the total standard deviation as shown in Table 3:

[0146] Table 3

[0147]

[0148] R_xx refers to the resistance value of the two MTJs in parallel in the corresponding state, and σ_xx refers to the total standard deviation in the reading circuit in the corresponding state.

[0149] The k value means that the resistance of MTJ2 is k times that of MTJ1. In order to improve the read performance, the read failure probability can be calculated to minimize the read failure probability, thereby determining the k value.

[0150] The steps for reading are as follows:

[0151] Step 0: WL high level turns on N1 and N2, REN high level shorts BL1 and BL2, and only BL1 is set to high level. The read current flows through the two parallel MTJs to generate data voltage, and the corresponding reference resistor generates reference voltage.

[0152] Step 1: Compare the data voltage with the reference voltage 1. If the data voltage is large, MTJ1 is in a high-resistance anti-parallel state and the data is 1X (X is 0 or 1); if the data voltage is small, MTJ1 is in a low-resistance parallel state and the data is 0X.

[0153] Step 2: If the data is 1X, compare the data voltage with the reference voltage 2. If the data voltage is larger, MTJ2 is in a high-resistance antiparallel state and the data is 11; if the data voltage is smaller, MTJ2 is in a low-resistance parallel state and the data is 10. If the data is 0X, compare the data voltage with the reference voltage 0. If the data voltage is larger, MTJ2 is in a high-resistance antiparallel state and the data is 01; if the data voltage is smaller, MTJ2 is in a low-resistance parallel state and the data is 00.

[0154] Optionally, the shape of the magnetic tunnel junction on the spin-orbit coupling layer 1 can be any one of a cube, a cylinder, a square, an elliptical cylinder, etc. The bottom surface of at least one magnetic tunnel junction provided on the spin-orbit coupling layer 1, i.e., the bottom surface of the free layer 2, is coupled to the spin-orbit coupling layer 1.

[0155] Preferably, the spin-orbit coupling layer 1 can be rectangular, so that the top surface area of ​​the spin-orbit coupling layer 1 is larger than the area occupied by the multiple magnetic tunnel junctions provided on the spin-orbit coupling layer 1. In other words, multiple magnetic tunnel junctions can be provided on the spin-orbit coupling layer 1, and the outer edges of the multiple magnetic tunnel junctions are located inside the outer edge of the spin-orbit coupling layer 1. The spin-orbit coupling layer 1 can preferably be made of a heavy metal strip film or an antiferromagnetic strip film.

[0156] In a preferred embodiment, when the magnetic random access memory unit inputs current into the spin-orbit coupling layer 1 and the magnetic tunnel junction, electrodes can be provided on the spin-orbit coupling layer 1 and the magnetic tunnel junction. For example, a top electrode 5 is provided on the top of the magnetic tunnel junction, and an input electrode 6 and an output electrode are provided on opposite sides of the spin-orbit coupling layer 1. Preferably, the material of the electrodes can be any one of tantalum Ta, aluminum Al, gold Au, or copper Cu.

[0157] Preferably, the material of the free layer 2 and the fixed layer 4 may be a ferromagnetic metal, and the material of the barrier layer 3 may be an oxide. The magnetic tunnel junction has perpendicular magnetic anisotropy, which means that the magnetization direction of the free layer 2 and the fixed layer 4 forming the magnetic tunnel junction is in the vertical direction. The ferromagnetic metal may be a mixed metal material formed by at least one of cobalt iron CoFe, cobalt iron boron CoFeB or nickel iron NiFe, and the proportions of the mixed metal materials may be the same or different. The oxide may be one of oxides such as magnesium oxide MgO or aluminum oxide Al2O3, which is used to generate a tunneling magnetoresistance effect. In practical applications, the ferromagnetic metal and the oxide may also be made of other feasible materials, and the present invention is not limited to this.

[0158] The free layer 2 of the magnetic tunnel junction is in contact with and fixed to the spin-orbit coupling layer 1. The layers of the magnetic tunnel junction and the spin-orbit coupling layer 1 can be deposited on the substrate in sequence from bottom to top through traditional methods such as ion beam epitaxy, atomic layer deposition or magnetron sputtering, and then multiple magnetic tunnel junctions can be prepared through traditional nanodevice processing techniques such as photolithography and etching.

[0159] In a preferred embodiment, the spin-orbit coupling layer 1 is a spin-orbit coupling layer 1 composed of a heavy metal film, an antiferromagnetic film, or other materials. The heavy metal film or antiferromagnetic film can be formed into a rectangular shape, and its top area is preferably larger than the bottom area of ​​the outline formed by all magnetic tunnel junctions, so that one or more magnetic tunnel junctions can be arranged, and the bottom surface shape of the magnetic tunnel junction is completely embedded in the top surface shape of the heavy metal film or antiferromagnetic film. Preferably, the material of the spin-orbit coupling layer 1 can be selected from one of platinum (Pt), tantalum (Ta), or tungsten (W). In practical applications, the spin-orbit coupling layer 1 can also be formed of other feasible materials, and the present invention is not limited to this.

[0160] Those skilled in the art will appreciate that the switching element in this embodiment can be a transistor; in other embodiments, a diode can also be used. When implemented using a transistor, either an N-type transistor or a P-type transistor can be used. The high and low levels of various signals are coordinated with the transistor type to achieve the corresponding functions. Those skilled in the art will understand that turning on a P-type transistor requires a low-level signal, while turning on an N-type transistor requires a high-level signal. Therefore, using either an N-type transistor or a P-type transistor and setting the level of the transistor gate (control terminal) to achieve the corresponding on / off function achieves the data reading purpose of the present invention. The control terminal of the transistor provided in the embodiments of the present invention is the gate, and the first terminal can be the source, while the second terminal is the drain, or vice versa, the first terminal can be the drain, while the second terminal is the source. This is not limited in the present invention and can be appropriately selected based on the transistor type.

[0161] Furthermore, the transistor provided in the embodiments of the present invention may be a field-effect transistor, which may be either an enhancement-mode field-effect transistor or a depletion-mode field-effect transistor. The transistor may utilize a low-temperature polysilicon TFT, which reduces manufacturing costs and product power consumption and provides faster electron mobility. Alternatively, an oxide semiconductor TFT may be employed.

[0162] In this embodiment, the magnetic tunnel junction includes a top pinned layer 4, a free layer 2 in contact with a spin-orbit coupling layer 1, and a barrier layer 3 disposed between the pinned layer 4 and the free layer 2. The magnetic tunnel junction is a three-layer structure and includes only one free layer 2. In other embodiments, the free layer 2 may be provided in multiple layers, i.e., more than two free layers 2. The magnetic tunnel junction then includes a top pinned layer 4, multiple free layers 2, and a barrier layer 3 disposed between each two adjacent layers, with the bottom free layer 2 disposed in contact with the spin-orbit coupling layer 1. For example, in a specific example, when two free layers 2 are included, the magnetic storage cell structure may include a spin-orbit coupling layer 1, a second free layer sequentially disposed on the spin-orbit coupling layer 1, a barrier layer 3, a first free layer, a barrier layer 3, and a pinned layer 4.

[0163] Based on the same principle, this embodiment also discloses a magnetic random access memory. In this embodiment, the magnetic random access memory includes a plurality of magnetic random access memory units as described in the present invention arranged in an array.

[0164] like Figure 4 As shown, the memory includes four magnetic random access memory cells arranged in a 2*2 array, wherein the switching elements of each column of memory cells share a write control line (WL0, WL1), the switching elements of each row of memory cells share a first write line (SL10, SL11) and a second write line (SL20, SL21), all memory cells share a read control line REN, and the switching elements of each row of memory cells share a first control line (BL10, BL20) and a second control line (BL11, BL21).

[0165] Since the principle of solving the problem of this memory is similar to that of the above magnetic random access memory unit, the implementation of this memory can refer to the implementation of the above magnetic random access memory unit, and will not be repeated here.

[0166] Magnetic random access memory (RAM) includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of RAM applications include, but are not limited to, random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital compact disc (DVD) or other optical storage, magnetic cassettes, magnetic tape, disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device.

[0167] Based on the same principle, this embodiment also discloses a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor.

[0168] The processor and / or the memory include the magnetic random access memory unit as described in this embodiment.

[0169] The magnetic random access memory unit described in the above embodiments can be provided in a product device having a certain function. A typical implementation device is a computer device. Specifically, the computer device can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0170] In a typical example, a computer device specifically includes a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor and / or the memory include the magnetic random access memory unit as described in this embodiment.

[0171] Reference below Figure 6 , which shows a structural diagram of a computer device 600 suitable for implementing an embodiment of the present invention.

[0172] like Figure 6 As shown, computer device 600 includes a central processing unit (CPU) 601, which can perform various appropriate tasks and processes according to programs stored in a read-only memory (ROM) 602 or programs loaded from a storage unit 608 into a random access memory (RAM) 603. Various programs and data required for the operation of computer device 600 are also stored in RAM 603. CPU 601, ROM 602, and RAM 603 are connected to each other via a bus 604. An input / output (I / O) interface 605 is also connected to bus 604.

[0173] The following components are connected to the I / O interface 605: an input section 606 including a keyboard, mouse, and the like; an output section 607 including devices such as a cathode ray tube (CRT), a liquid crystal display (LCD), and speakers; a storage section 608 including devices such as a hard disk; and a communication section 609 including a network interface card such as a LAN card or a modem. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to the I / O interface 605 as needed. Removable media 611, such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, is installed in the drive 610 as needed, so that computer programs read from the media can be installed in the storage section 608 as needed.

[0174] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0175] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0176] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0177] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0178] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROMs, optical storage, etc.) containing computer-usable program code.

[0179] The present invention may be described in the general context of computer-executable instructions, such as program modules, executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, and the like that perform specific tasks or implement specific abstract data types. The present invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media, including storage devices.

[0180] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0181] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A magnetic random access memory cell, characterized in that: It includes a spin-orbit coupling layer, a plurality of magnetic tunnel junctions arranged on the spin-orbit coupling layer, and a VCMA control module; The VCMA control module is used to input a VCMA voltage to the corresponding magnetic tunnel junction to change the perpendicular anisotropy state of the magnetic tunnel junction; The plurality of magnetic tunnel junctions include at least a first magnetic tunnel junction and a second magnetic tunnel junction, wherein a cross-sectional dimension of the first magnetic tunnel junction in contact with the spin-orbit coupling layer is larger than a cross-sectional dimension of the second magnetic tunnel junction in contact with the spin-orbit coupling layer; The spin-orbit coupling layer includes a first region where the first magnetic tunnel junction is arranged and a second region where the second magnetic tunnel junction is arranged, and a cross-sectional area of ​​the first region for inputting current is larger than a cross-sectional area of ​​the second region for inputting current; The magnetic random access memory cell further comprises a first write line, a second write line, a write control line, a first control line and a second control line, and the magnetic random access memory cell further comprises a first switching element and a second switching element; A first end of the first switching element is connected to the first write line, and a second end is connected to the first input end of the spin-orbit coupling layer; A first end of the second switch element is connected to the second write line, and a second end is connected to the second input end of the spin-orbit coupling layer; The control ends of the first switching element and the second switching element are connected to the write control line; The first control line and the second control line are directly connected to the top of the first magnetic tunnel junction and the second magnetic tunnel junction respectively through wires; The VCMA control module is configured to input a low-level VCMA voltage to the corresponding magnetic tunnel junction to place the magnetic tunnel junction in a first perpendicular anisotropy state, and input a high-level VCMA voltage to the corresponding magnetic tunnel junction to place the magnetic tunnel junction in a second perpendicular anisotropy state, wherein the perpendicular anisotropy of the first perpendicular anisotropy state is greater than the perpendicular anisotropy of the second perpendicular anisotropy state; When the VCMA control module inputs a low-level VCMA voltage to the first magnetic tunnel junction, the critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value; when the VCMA control module inputs a high-level VCMA voltage to the first magnetic tunnel junction, the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value; When the VCMA control module inputs a low-level VCMA voltage to the second magnetic tunnel junction, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a third critical current value; when the VCMA control module inputs a high-level VCMA voltage to the second magnetic tunnel junction, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value; The first critical current value is greater than the second critical current value; the third critical current value is greater than the fourth critical current value; The steps of reading the first magnetic tunnel junction and the second magnetic tunnel junction are as follows: Step 0: The write control line is at a high level to turn on the first and second switch elements. The read control line is at a high level to short-circuit the first and second control lines. At the same time, only the first control line is set to a high level. The read current flows through the two parallel magnetic tunnel junctions to generate a data voltage, and the corresponding reference resistor generates a reference voltage. Step 1: Compare the data voltage with the reference voltage 1. If the data voltage is larger, the first magnetic tunnel junction is in a high-resistance antiparallel state, and the data is 1X, where X is 0 or 1. If the data voltage is smaller, the first magnetic tunnel junction is in a low-resistance parallel state, and the data is 0X. Step 2: If the data is 1X, compare the data voltage with the reference voltage 2. If the data voltage is larger, the second magnetic tunnel junction is in a high resistance antiparallel state, and the data is 11; if the data voltage is smaller, the second magnetic tunnel junction is in a low resistance parallel state, and the data is 10. If the data is 0X, compare the data voltage with the reference voltage 0. If the data voltage is larger, the second magnetic tunnel junction is in a high resistance antiparallel state, and the data is 01; if the data voltage is smaller, the second magnetic tunnel junction is in a low resistance parallel state, and the data is 00. The reference resistors include reference resistor 0, reference resistor 1 and reference resistor 2. Reference resistor 0 is , reference resistor 1 is , reference resistor 2 is ,in 、 、 and Refers to the resistance value of two magnetic tunnel junctions in parallel in the corresponding state, 、 、 and Refers to the total standard deviation in the reading circuit under the corresponding state; Also comprising a third switching element and a read control line; The first end and the second end of the third switch element are connected to the first control line and the second control line respectively, and the control end of the third switch element is connected to the read control line.

2. The magnetic random access memory cell according to claim 1, wherein The first critical current value is greater than the fourth critical current value; the third critical current value is greater than the second critical current value.

3. The magnetic random access memory cell according to claim 1, wherein The first magnetic tunnel junction and the second magnetic tunnel junction include a fixed layer, a barrier layer and a free layer arranged in sequence from top to bottom; The bottom surfaces of the free layers of the first magnetic tunnel junction and the second magnetic tunnel junction are fixedly connected to the spin-orbit coupling layer.

4. The magnetic random access memory cell according to claim 1, wherein: When the current input into the spin-orbit coupling layer is greater than the critical switching current of the free layer of the first magnetic tunnel junction, the resistance state of the first magnetic tunnel junction changes deterministically; when the current input into the spin-orbit coupling layer is less than the critical switching current of the free layer of the first magnetic tunnel junction, the resistance state of the first magnetic tunnel junction remains unchanged; When the current input into the spin-orbit coupling layer is greater than the critical switching current of the free layer of the second magnetic tunnel junction, the resistance state of the second magnetic tunnel junction changes deterministically. When the current input into the spin-orbit coupling layer is less than the critical switching current of the free layer of the second magnetic tunnel junction, the resistance state of the second magnetic tunnel junction remains unchanged.

5. A magnetic random access memory, characterized in that: The invention comprises a plurality of magnetic random access memory cells as claimed in any one of claims 1 to 4 arranged in an array.

6. A method for writing data into a magnetic random access memory cell according to any one of claims 1 to 4, characterized in that: include: determining a spin-orbit torque current based on data to be written and inputting the spin-orbit torque current into the spin-orbit coupling layer, wherein if the data to be written is "00", the spin-orbit torque current is a write current in a first direction, and a current density of the write current is greater than a critical switching current of the first magnetic tunnel junction; If the data to be written is "01", the spin-orbit torque current includes a first write current in a first direction and a second write current in a second direction input sequentially, a current density of the first write current is greater than a critical switching current of the first magnetic tunnel junction, and a current density of the second write current is greater than a critical switching current of the second magnetic tunnel junction and less than a critical switching current of the first magnetic tunnel junction; If the data to be written is "10", the spin-orbit torque current includes a first write current in a second direction and a second write current in a first direction input sequentially, a current density of the first write current is greater than a critical switching current of the first magnetic tunnel junction, and a current density of the second write current is greater than a critical switching current of the second magnetic tunnel junction and less than a critical switching current of the first magnetic tunnel junction; If the data to be written is “11”, the spin-orbit torque current is a write current in the second direction, and the current density of the write current is greater than the critical switching current of the first magnetic tunnel junction.

7. The method for writing data into a magnetic random access memory cell according to claim 6, wherein: When writing "00", a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the write current in the first direction is greater than the second critical current value; When "01" is written, a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the first write current in the first direction is greater than the second critical current value; a low-level VCMA voltage is input to the first magnetic tunnel junction, and a high-level VCMA voltage is input to the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the first write current in the first direction is greater than the fourth critical current value and less than the first critical current value; When "10" is written, a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the first write current in the second direction is greater than the second critical current value; a low-level VCMA voltage is input to the first magnetic tunnel junction, and a high-level VCMA voltage is input to the second magnetic tunnel junction, so that the critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, the critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and the current density of the second write current in the first direction is greater than the fourth critical current value and less than the first critical current value; When "11" is written, a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical flipping current for flipping the free layer of the first magnetic tunnel junction is the second critical current value, the critical flipping current for flipping the free layer of the second magnetic tunnel junction is the fourth critical current value, and the current density of the write current in the second direction is greater than the second critical current value.

8. The method for writing data into a magnetic random access memory cell according to claim 6, wherein: The step of determining the spin-orbit torque current input to the spin-orbit coupling layer based on the data to be written comprises: reading the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction; determining whether the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction need to be changed according to the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction and the data to be written; When data "0" is input only to the first magnetic tunnel junction, a high-level VCMA voltage is input to the first magnetic tunnel junction, and a low-level VCMA voltage is input to the second magnetic tunnel junction, so that a critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, a critical switching current for flipping the free layer of the second magnetic tunnel junction is a third critical current value, and a current density of a write current in the first direction is greater than the second critical current value and less than the third critical current value; When data "1" is input only to the first magnetic tunnel junction, a high-level VCMA voltage is input to the first magnetic tunnel junction, and a low-level VCMA voltage is input to the second magnetic tunnel junction, so that a critical switching current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, a critical switching current for flipping the free layer of the second magnetic tunnel junction is a third critical current value, and a current density of a write current in the second direction is greater than the second critical current value and less than the third critical current value; When data "1" is input only to the second magnetic tunnel junction, a low-level VCMA voltage is input to the first magnetic tunnel junction, a high-level VCMA voltage is input to the second magnetic tunnel junction, a critical switching current for flipping the free layer of the first magnetic tunnel junction is a first critical current value, a critical switching current for flipping the free layer of the second magnetic tunnel junction is a fourth critical current value, and a current density of a write current in the first direction is greater than the fourth critical current value and less than the first critical current value; When only data "0" is input to the first magnetic tunnel junction, a high-level VCMA voltage is input to the first magnetic tunnel junction, and a low-level VCMA voltage is input to the second magnetic tunnel junction, so that the critical flipping current for flipping the free layer of the first magnetic tunnel junction is a second critical current value, and the critical flipping current for flipping the free layer of the second magnetic tunnel junction is a third critical current value, and the current density of the write current in the first direction is greater than the second critical current value and less than the third critical current value.

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