Magnetic random access memory unit, memory and data writing method

Abstract

The invention discloses a magnetic random access memory unit, a memory and a data writing method. The magnetic random access memory unit comprises a spin-orbit coupling layer, a plurality of magnetic tunnel junctions arranged on the spin-orbit coupling layer and a VCMA regulation and control module, the plurality of magnetic tunnel junctions at least comprise a first magnetic tunnel junction and a second magnetic tunnel junction, and the sectional dimension of the first magnetic tunnel junction in contact with the spin-orbit coupling layer is larger than the sectional dimension of the second magnetic tunnel junction in contact with the spin-orbit coupling layer; the spin-orbit coupling layer comprises a first region where the first magnetic tunnel junction is arranged and a second region where the second magnetic tunnel junction is arranged, and the cross-sectional area of input current of the first region is larger than that of input current of the second region. The bit error rate of writing operation of the magnetic random storage unit can be reduced, and the storage density of the storage unit is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices. More specifically, it relates to a magnetic random access memory cell, a memory, and a data writing method. Background Art

[0002] With the continuous reduction of the semiconductor process size, Moore's Law has slowed down, and the increase in leakage current and interconnect delay have become bottlenecks for traditional CMOS memories. Magnetic random access memory (MRAM) has the advantages of being rewritable, non-volatile, fast read / write speed, radiation resistance, etc., and is expected to become a general-purpose memory. It is an ideal device for constructing the next-generation non-volatile main memory and cache. The magnetic tunnel junction is the basic storage unit of the magnetic random access memory. The second-generation spin-transfer torque magnetic random access memory (STT-MRAM) has disadvantages such as a long incubation time and read / write interference, which limit its further development. Spin-orbit torque magnetic random access memory (SOT-MRAM) has received extensive attention from the industrial and academic communities due to its advantages such as fast writing speed, separated read / write paths, and low power consumption.

[0003] Currently, the SOT-MRAM based on spin-orbit torque (SOT) is expected to become the core device for the next-generation writing technology of MRAM. Compared with STT-MRAM, the writing current of SOT-MRAM flows through the underlying spin-orbit coupling layer, avoiding the risk of breakdown. Moreover, SOT-MRAM theoretically has an ultra-fast writing speed of less than 1 ns and is expected to be used as a cache. In addition, the heavy metal forming the spin-orbit coupling layer has low resistivity and low power consumption, and the read / write branches of the storage device based on SOT-MRAM are separated, allowing a thicker barrier layer. In order to increase the storage density of the magnetic random access memory cell, in the prior art, multiple magnetic tunnel junctions (MTJs) are arranged in one storage unit. However, when one of the multiple magnetic tunnel junctions is written with data, other magnetic tunnel junctions may also be accidentally written, and the write operation error rate is relatively high. Summary of the Invention

[0004] An object of the present invention is to provide a magnetic random access memory cell to reduce the error rate of the write operation of the magnetic random access memory cell and increase the storage density of the storage unit. Another object of the present invention is to provide a magnetic random access memory. Still another object of the present invention is to provide a data writing method for the magnetic random access memory cell.

[0005] To achieve the above objects, the present invention adopts the following technical solutions: The present invention discloses a magnetic random access memory cell, which includes a spin-orbit coupling layer, a plurality of magnetic tunnel junctions disposed on the spin-orbit coupling layer, and a VCMA regulation module; The VCMA regulation module is configured 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 at least include a first magnetic tunnel junction and a second magnetic tunnel junction, and a cross-sectional size of the first magnetic tunnel junction in contact with the spin-orbit coupling layer is larger than a cross-sectional size 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, 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; It further includes 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 includes 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 a first input end of the spin-orbit coupling layer; A first end of the second switching element is connected to the second write line, and a second end is connected to a second input end of the spin-orbit coupling layer; 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 respectively connected to tops of the first magnetic tunnel junction and the second magnetic tunnel junction.

[0006] Optionally, the VCMA regulation module is configured to input a VCMA voltage to the corresponding magnetic tunnel junction to make the first magnetic tunnel junction in a first perpendicular anisotropy state and make the second magnetic tunnel junction in a second perpendicular anisotropy state, and a perpendicular anisotropy of the first perpendicular anisotropy state is greater than a perpendicular anisotropy of the second perpendicular anisotropy state; When the VCMA regulation module inputs a low-level VCMA voltage to the first magnetic tunnel junction, a critical switching current for flipping a free layer of the first magnetic tunnel junction is a first critical current value, and when the VCMA regulation 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 regulation module inputs a low-level VCMA voltage to the second magnetic tunnel junction, a critical switching current for flipping a free layer of the second magnetic tunnel junction is a third critical current value, and when the VCMA regulation 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.

[0007] Optionally, 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.

[0008] Optionally, the first magnetic tunnel junction and the second magnetic tunnel junction include a fixed layer, a barrier layer, and a free layer arranged from top to bottom in sequence; The bottom surface of the free layer of the first magnetic tunnel junction and the second magnetic tunnel junction is fixedly connected to the spin-orbit coupling layer.

[0009] Optionally, the critical switching current of the free layer of the first magnetic tunnel junction is a first current threshold, the critical switching current of the free layer of the second magnetic tunnel junction is a second current threshold, and the first current threshold is greater than the second current threshold; When the current density of the spin-orbit torque current input by the spin-orbit coupling layer is greater than the first current threshold, 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 threshold and the 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; When the spin-orbit torque current input by the spin-orbit coupling layer is less than the second current threshold, the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction remain unchanged.

[0010] Optionally, it further includes a third switching element and a read control line; The first end and the second end of the third switching element are respectively connected to the first control line and the second control line, and the control end of the third switching element is connected to the read control line.

[0011] The present invention also discloses a magnetic random access memory, including a plurality of magnetic random access memory units arranged in an array as described above.

[0012] The present invention also discloses a method for writing data into a magnetic random access memory unit, including: Determining a spin-orbit torque current based on the data to be written and inputting the spin-orbit torque current into the spin-orbit coupling layer, wherein, when the data to be written is "00", the spin-orbit torque current is a write current in a first direction, and the current density of the write current is greater than the critical switching current of the first magnetic tunnel junction; When 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 that are input in sequence. The current density of the first write current is greater than the critical switching current of the first magnetic tunnel junction, and the current density of the second write current is greater than the critical switching current of the second magnetic tunnel junction and less than the critical switching current of the first magnetic tunnel junction; When 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 that are input in sequence. The current density of the first write current is greater than the critical switching current of the first magnetic tunnel junction, and the current density of the second write current is greater than the critical switching current of the second magnetic tunnel junction and less than the critical switching current of the first magnetic tunnel junction; When 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.

[0013] 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 the free layer of the first magnetic tunnel junction to flip is a second critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is a fourth critical current value. The current density of the write current in the first direction is greater than the second critical current value; When writing "01", 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 the free layer of the first magnetic tunnel junction to flip is a second critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is a fourth critical current value. 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 the free layer of the first magnetic tunnel junction to flip is a first critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is a fourth critical current value. 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 writing "10", a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction. The critical switching current for flipping the free layer of the first magnetic tunnel junction is the second critical current value, and the critical switching current for flipping the free layer of the second magnetic tunnel junction is the fourth critical current value. 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. The critical switching current for flipping the free layer of the first magnetic tunnel junction is the first critical current value, and the critical switching current for flipping the free layer of the second magnetic tunnel junction is the fourth critical current value. 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 writing "11", a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction. The critical switching current for flipping the free layer of the first magnetic tunnel junction is the second critical current value, and the critical switching current for flipping the free layer of the second magnetic tunnel junction is the fourth critical current value. The current density of the write current in the second direction is greater than the second critical current value.

[0014] Optionally, determining the spin-orbit torque current input to the spin-orbit coupling layer based on the data to be written includes: 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 only writing the data "0" 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. The critical switching current for flipping the free layer of the first magnetic tunnel junction is the second critical current value, and the critical switching current for flipping the free layer of the second magnetic tunnel junction is the third critical current value. 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. When only writing the data "1" 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. The critical switching current for flipping the free layer of the first magnetic tunnel junction is the second critical current value, and the critical switching current for flipping the free layer of the second magnetic tunnel junction is the third critical current value. The current density of the write current in the second direction is greater than the second critical current value and less than the third critical current value. When only inputting data "1" to the second magnetic tunnel junction, input a low-level VCMA voltage to the first magnetic tunnel junction and a high-level VCMA voltage to the second magnetic tunnel junction. The critical switching current for the free layer of the first magnetic tunnel junction to flip is a first critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is a fourth critical current value. The current density of the write current in the first direction is greater than the fourth critical current value and less than the first critical current value; When only inputting data "0" to the second magnetic tunnel junction, input a low-level VCMA voltage to the first magnetic tunnel junction and a high-level VCMA voltage to the second magnetic tunnel junction. The critical switching current for the free layer of the first magnetic tunnel junction to flip is a first critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is a fourth critical current value. 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.

[0015] The beneficial effects of the present invention are as follows: In the magnetic random access memory cell of the present invention, at least a first magnetic tunnel junction and a second magnetic tunnel junction are provided on the spin-orbit coupling layer, such that the cross-sectional size of the first magnetic tunnel junction and the cross-sectional area of the input current of the spin-orbit coupling layer provided are larger than those of the second magnetic tunnel junction, so as to increase the difference in the critical switching currents of the free layers of the first magnetic tunnel junction and the second magnetic tunnel junction through the double structure difference, and reduce the error rate during data writing. In addition, the present invention also adjusts the states of the perpendicular anisotropies of the first magnetic tunnel junction and the second magnetic tunnel junction respectively through a VCMA regulation module, so as to further adjust the critical switching currents of the free layers of the first magnetic tunnel junction and the second magnetic tunnel junction according to the needs of the written data, realize accurate data writing, and reduce the bit error rate of data writing. Description of the Drawings

[0016] The following further elaborates on the specific embodiments of the present invention with reference to the drawings.

[0017] Figure 1 The structural schematic diagram showing a specific embodiment of the magnetic random access memory cell of the present invention; Figure 2 The schematic diagram showing the write path of a specific embodiment of the magnetic random access memory cell of the present invention; Figure 3 The schematic diagram showing the read path of a specific embodiment of the magnetic random access memory cell of the present invention; Figure 4 The schematic diagram showing a specific example of the magnetic random access memory of the present invention; Figure 5 The schematic diagram showing the correspondence between the written data and the signal of a specific embodiment of the magnetic random access memory cell of the present invention; Figure 6Schematic structural diagram of a computer device including the magnetic random access memory of the present invention. Detailed implementation manners

[0018] To more clearly illustrate the present invention, the present invention will be further described below in conjunction with preferred embodiments and the accompanying drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0019] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected", and "fixed" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be directly connected, or indirectly connected through an intermediate medium, and may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0020] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but in contact through additional features therebetween.

[0021] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "left", and "right" are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying operations, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0022] According to one aspect of the present invention, this embodiment discloses a magnetic random access storage unit. As Figures 1-3 shown, in this embodiment, the magnetic random access storage unit includes a spin-orbit coupling layer 1, a plurality of magnetic tunnel junctions provided on the spin-orbit coupling layer 1, and a VCMA regulation module.

[0023] Wherein, the VCMA regulation 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.

[0024] The plurality of magnetic tunnel junctions at least include a first magnetic tunnel junction MTJ1 and a second magnetic tunnel junction MTJ2, and 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.

[0025] The spin - orbit coupling layer 1 includes a first region where the first magnetic tunnel junction MTJ1 is disposed and a second region where the second magnetic tunnel junction MTJ2 is disposed, and the cross - sectional area of the input current in the first region is larger than that in the second region.

[0026] 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, and the magnetic random access memory cell further includes a first switching element N1 and a second switching element N2.

[0027] The first end of the first switching element N1 is connected to the first write line SL1, and the second end is connected to the first input end of the spin - orbit coupling layer 1.

[0028] The first end of the second switching element N2 is connected to the second write line SL2, and the second end is connected to the second input end of the spin - orbit coupling layer 1.

[0029] The control ends of the first switching element N1 and the second switching element N2 are connected to the write control line WL; The first control line BL1 and the second control line BL2 are respectively connected to the tops of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2.

[0030] Among them, by controlling the first switching element N1 and the second switching element N2 to conduct through the write control line WL, the first write line SL1 and the second write line SL2 can form a loop with the corresponding memory cell, and an SOT current is input to the spin - orbit coupling layer 1 of the memory cell to realize the data writing function. At the same time, a VCMA voltage can be input through the first control line BL1 and the second control line BL2 connected to the top of the magnetic tunnel junction to control the magnetic tunnel junction for writing data, and assist in realizing the deterministic writing of data. In the present invention, each magnetic random access memory cell can be controlled for writing only through the first switching element N1 and the second switching element N2.

[0031] Optionally, input electrodes 6 can be disposed at both ends of the spin - orbit coupling layer 1 of the magnetic random access memory cell, and are electrically connected to the switching element through the input electrodes 6. A top electrode 5 can be disposed at the top of the magnetic tunnel junction and is electrically connected to the first control line BL1 or the second control line BL2.

[0032] In the magnetic random access memory cell of the present invention, at least a first magnetic tunnel junction MTJ1 and a second magnetic tunnel junction MTJ2 are provided on the spin-orbit coupling layer 1, such that the cross-sectional size 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, so as to increase the difference in the critical switching currents of the free layers 2 of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 through the dual structure difference, and reduce the error rate during data writing. In addition, the present invention also adjusts the states of the perpendicular anisotropies of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 respectively through the VCMA regulation module, so as to further adjust the critical switching currents of the free layers 2 of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 according to the needs of the written data, achieve accurate data writing, and reduce the bit error rate during data writing.

[0033] Moreover, in the prior art, for a memory cell with multiple MTJs provided on a spin-orbit coupling layer, a control transistor needs to be provided at the top of each magnetic tunnel junction for writing and reading respectively to avoid the mutual influence of data writing and reading between different MTJs. However, this cell structure requires more transistors. In the memory cell of the present application, the cross-sectional sizes 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 the critical currents for the magnetic moment reversal of the first magnetic tunnel junction and the second magnetic tunnel junction is greater. Then, the top of the MTJ can be directly connected to the control line for inputting the VCMA voltage, and no switching elements such as transistors need to be provided at the top of the MTJ. Data writing and reading of different MTJs will not affect each other, without considering the influence of the voltage drop of the switching element on the voltage, and there will be no situation where the VCMA voltage damages the switching element. And the memory cell of the present application only needs two switching devices to control the deterministic writing of data of multiple magnetic tunnel junctions in the cell, reduces the number of switching devices, saves the cell area, and effectively increases the storage density.

[0034] In an optional embodiment, the VCMA regulation module is used to input a VCMA voltage to the corresponding magnetic tunnel junction to make the first magnetic tunnel junction MTJ1 in a first perpendicular anisotropy state and make the second magnetic tunnel junction MTJ2 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.

[0035] 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 regulation module can change the PMA phenomenon of the magnetic layer of the MTJ by inputting an external VCMA voltage to the magnetic tunnel junction (MTJ). The change in PMA will affect the critical switching condition of the MTJ. By applying a VCMA voltage on the top of the MTJ, the VCMA effect changes the PMA of the MTJ, weakens the stability of the free layer 2, makes it easier to switch, and reduces the critical switching current density of the MTJ.

[0036] Therefore, in the present invention, the cross-sectional area of the first magnetic tunnel junction MTJ1 in contact with the spin-orbit coupling layer 1 is 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 corresponding to the resistance state is greater than that of the first magnetic tunnel junction MTJ1. Moreover, the cross-sectional area of the spin-orbit coupling layer 1 where the first magnetic tunnel junction MTJ1 is arranged is larger than the cross-sectional area of the spin-orbit coupling layer 1 where the second magnetic tunnel junction MTJ2 is arranged, that is, at the same thickness, the width of the spin-orbit coupling layer 1 where the first magnetic tunnel junction MTJ1 is arranged is greater than the width of the spin-orbit coupling layer 1 where the second magnetic tunnel junction MTJ2 is arranged, so that 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 gap between the two MTJs is further widened. Among them, the VCMA regulation module applies a VCMA voltage to the two MTJs to make the perpendicular anisotropy of the first perpendicular anisotropy state greater than the perpendicular anisotropy of the second perpendicular anisotropy state, further increasing the current density gap of the critical switching currents of the two MTJs. Through the above settings, the critical switching current required by the first magnetic tunnel junction MTJ1 is much greater than that of the second magnetic tunnel junction MTJ2, improving the reliability of data writing and reducing the writing error rate.

[0037] In an alternative embodiment, when the VCMA regulation module inputs a low-level VCMA voltage to the first magnetic tunnel junction MTJ1, the critical switching current for the free layer of the first magnetic tunnel junction MTJ1 to flip is a first current value. When a low-level VCMA voltage is input to the second magnetic tunnel junction MTJ2, the critical switching current for the free layer of the second magnetic tunnel junction MTJ2 to flip is a second current value, and the first current value is greater than the second current value; When the VCMA regulation module inputs a high-level VCMA voltage to the first magnetic tunnel junction MTJ1, the critical switching current for the free layer of the first magnetic tunnel junction MTJ1 to flip is a third current value. When a high-level VCMA voltage is input to the second magnetic tunnel junction MTJ2, the critical switching current for the free layer of the second magnetic tunnel junction MTJ2 to flip is a fourth current value, and the third critical current value is greater than the fourth critical current value.

[0038] Specifically, the VCMA control module adjusts the perpendicular anisotropy states of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 by applying high or low levels to the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2, and at the same time adjusts the magnitude of the SOT current to change the corresponding resistance states of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2, so as to achieve the purpose of writing specific data.

[0039] Preferably, the first critical current value is also greater than the fourth critical current value; the third critical current value is also greater than the second critical current value.

[0040] In an alternative 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 switching current for the free layer of the first magnetic tunnel junction MTJ1 to switch is the first current value, and the critical switching current for the free layer of the second magnetic tunnel junction MTJ2 to switch is the 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.

[0041] In another alternative embodiment, when the VCMA regulation 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 switching current for the free layer of the first magnetic tunnel junction MTJ1 to flip is the third current value, and the critical switching current for the free layer of the second magnetic tunnel junction MTJ2 to flip is the 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. Conversely, 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 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 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 states of the first magnetic tunnel junction and the second magnetic tunnel junction remain unchanged.

[0042] In yet another alternative embodiment, when the VCMA regulation 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 switching current for the free layer of the first magnetic tunnel junction MTJ1 to flip is the first current value, and the critical switching current for the free layer of the second magnetic tunnel junction MTJ2 to flip is the fourth current value. 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 switching 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, thus effectively reducing the possibility of miswriting and improving the device reliability.

[0043] In still another alternative embodiment, when the VCMA regulation module inputs a high-level VCMA voltage to the first magnetic tunnel junction MTJ1 and also inputs a high-level VCMA voltage to the second magnetic tunnel junction MTJ2, the critical switching current for the free layer of the first magnetic tunnel junction MTJ1 to flip is a third current value, and the critical switching current for the free layer of the second magnetic tunnel junction MTJ2 to flip 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.

[0044] Therefore, it should be noted that those skilled in the art can set the adjustment method of the perpendicular anisotropy state of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 by the VCMA regulation module and the specific structure of the VCMA regulation module according to actual needs, and the present invention does not limit this. Other technical solutions based on the same inventive concept should also be within the protection scope of the present invention.

[0045] In an alternative 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.

[0046] The bottom surface of the free layer 2 of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 is fixedly connected to the spin-orbit coupling layer 1.

[0047] 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 directions of the fixed layer 4 and the free layer 2, and the magnetization directions of the free layer 2 and the fixed layer 4 are determined by the magnetic moment directions, and the flipping 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 switching current of the free layer 2, the magnetic moment direction of the free layer 2 undergoes a deterministic flip corresponding to the SOT current. Thus, 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 change of the resistance state of the magnetic tunnel junction.

[0048] When the magnetic moment directions of the fixed layer 4 and the free layer 2 are the same, the magnetic tunnel junction is in a low resistance state (low resistance state). When the magnetic moment directions of the fixed layer 4 and the free layer 2 are opposite, the magnetic tunnel junction is in a high resistance state (high resistance state). Different data can be pre-corresponded to the high resistance state and the low resistance state of the magnetic tunnel junction respectively. For example, it is preset that the high resistance state corresponds to the data "1" and the low resistance state corresponds to the data "0". Then, by inputting current or voltage to the magnetic tunnel junction through a reading circuit, according to the change of the current or voltage, it can be determined whether the resistance state of the magnetic tunnel junction is a high resistance state or a low resistance state. According to the resistance state of the magnetic tunnel junction, it can be determined whether the data stored in the magnetic tunnel junction is "1" or "0". Among them, the ranges of the high resistance state and the low resistance state are determined by common technical means in the art. Those skilled in the art can determine the resistance value ranges of the high resistance state and the low resistance state of the magnetic tunnel junction according to common general knowledge, and the present invention will not elaborate herein.

[0049] In an alternative 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; When the current density of the spin-orbit torque current input by the spin-orbit coupling layer 1 is greater than the first current threshold, the resistance states of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 change deterministically; When the spin-orbit torque current input by the spin-orbit coupling layer 1 is between the first current threshold and the 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; When the spin-orbit torque current input by the spin-orbit coupling layer 1 is less than the second current threshold, the resistance states of the first magnetic tunnel junction MTJ1 and the second magnetic tunnel junction MTJ2 remain unchanged.

[0050] It can be understood that due to the cross-section of the free layer 2 of the magnetic tunnel junction and the function of the VCMA adjustment module, the critical switching current of the free layer 2 of the first magnetic tunnel junction MTJ1 is greater than that of the second magnetic tunnel junction MTJ2. Thus, when the spin-orbit torque current is input by the spin-orbit coupling layer 1, the current density flowing through the first magnetic tunnel junction MTJ1 is less than that of the second magnetic tunnel junction MTJ2. The magnitude of the SOT current required for the magnetic moment reversal of the free layer 2 of the first magnetic tunnel junction MTJ1 is much greater than that of the second magnetic tunnel junction MTJ2. The current margin for writing data into different magnetic tunnels becomes larger, improving the accuracy of writing data and reducing the bit error rate.

[0051] During the write operation, as Figure 2 shown, Figure 2In the figure, the dashed line indicates the direction of the write current Iwrite. The first control line BL1 and the second control line BL2 respectively provide BL1 and BL2 voltages (BL2 = VH, BL1 = GND) for MTJ1 and MTJ2 through the top electrodes 5 of the MTJs, so that the critical switching current density of MTJ1 is greater than that of MTJ2. At the same time, due to the different cross-sectional areas of the spin-orbit coupling layer 1, when a certain magnitude of current flows through, the current density at the bottom of MTJ1 is smaller. Adjust the write control line WL to a high level, N1 and N2 are turned on, voltages are applied to BL1, BL2, SL1, and SL2. The write current mainly passes through the two switching elements and the spin-orbit coupling layer 1 at the bottom of the two magnetic tunnel junctions, and a small amount of shunt current passes through the magnetic tunnel junctions. Since a voltage is applied to the top electrodes of the magnetic tunnel junctions, the thickness of the MTJ needs to be increased to prevent the MTJ from being broken down. Therefore, 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, and the influence of the shunt current on the write operation can be ignored.

[0052] In an alternative embodiment, the magnetic random access memory cell further includes a third switching element and a read control line.

[0053] The first end and the second end of the third switching element are respectively connected to the first control line BL1 and the second control line BL2, and the control end of the third switching element is connected to the read control line REN.

[0054] Specifically, during the read operation, as Figure 3 shown, Figure 3 in the figure, the dashed line indicates the direction of the read current Iread. WL at a high level turns on N1 and N2, REN is set to a high level to short-circuit BL1 and BL2, and BL1 at a high level causes the read current to flow through both MTJs simultaneously. The two MTJs are in parallel, and the resistance condition of the MTJ is judged according to the magnitude of the current, so as to judge the state of the MTJ.

[0055] The data writing method of the magnetic random access memory cell according to the embodiment of the present application includes: Determining a spin-orbit torque current based on the data to be written and inputting the spin-orbit torque current into the spin-orbit coupling layer. Wherein, when the data to be written is "00", the spin-orbit torque current is a write current in a first direction, and the current density of the write current is greater than the critical switching current of the first magnetic tunnel junction; When 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 in sequence. The current density of the first write current is greater than the critical switching current of the first magnetic tunnel junction, and the current density of the second write current is greater than the critical switching current of the second magnetic tunnel junction and less than the critical switching current of the first magnetic tunnel junction; When 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 that are sequentially input. The current density of the first write current is greater than the critical switching current of the first magnetic tunnel junction, and the current density of the second write current is greater than the critical switching current of the second magnetic tunnel junction and less than the critical switching current of the first magnetic tunnel junction; When 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.

[0056] Specifically, it can be understood that when writing data to the magnetic random access memory cell, different data combinations can be written to the two magnetic tunnel junctions by controlling the magnitude and direction of the VCMA voltage and the write current.

[0057] 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 the free layer of the first magnetic tunnel junction to flip is a second critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is a fourth critical current value. The current density of the write current in the first direction is greater than the second critical current value; When writing "01", 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 the free layer of the first magnetic tunnel junction to flip is a second critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is a fourth critical current value. 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 the free layer of the first magnetic tunnel junction to flip is a first critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is a fourth critical current value. 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 writing "10", a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction. The critical switching current for flipping the free layer of the first magnetic tunnel junction is the second critical current value, and the critical switching current for flipping the free layer of the second magnetic tunnel junction is the fourth critical current value. 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. The critical switching current for flipping the free layer of the first magnetic tunnel junction is the first critical current value, and the critical switching current for flipping the free layer of the second magnetic tunnel junction is the fourth critical current value. 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 writing "11", a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction. The critical switching current for flipping the free layer of the first magnetic tunnel junction is the second critical current value, and the critical switching current for flipping the free layer of the second magnetic tunnel junction is the fourth critical current value. The current density of the write current in the second direction is greater than the second critical current value.

[0058] To improve the data writing efficiency and accuracy, it is possible to determine whether the resistance state of the magnetic tunnel junction needs to be changed according to the data to be written. If it needs to be changed, only write data to the magnetic tunnel junction that needs to write data, reducing the operation steps of data writing. Then, determining the spin-orbit torque current input to the spin-orbit coupling layer based on the data to be written includes: Read the resistance states of the first magnetic tunnel junction and the second magnetic tunnel junction; Determine 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 only writing the data "0" 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. The critical switching current for flipping the free layer of the first magnetic tunnel junction is the second critical current value, and the critical switching current for flipping the free layer of the second magnetic tunnel junction is the third critical current value. 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. When only inputting data "1" 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. The critical switching current for the free layer of the first magnetic tunnel junction to flip is the second critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is the third critical current value. The current density of the write current in the second direction is greater than the second critical current value and less than the third critical current value; When only inputting data "1" 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. The critical switching current for the free layer of the first magnetic tunnel junction to flip is the first critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is the fourth critical current value. The current density of the write current in the first direction is greater than the fourth critical current value and less than the first critical current value; When only inputting data "0" 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. The critical switching current for the free layer of the first magnetic tunnel junction to flip is the first critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is the fourth critical current value. 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.

[0059] In a specific example, as Figures 1-3 shown, it is assumed that when the current passing through the spin-orbit coupling layer 1 of MTJ1 from SL1 to SL2 exceeds IC1, MTJ1 will flip to the parallel state (representing data 0); when the current passing through the spin-orbit coupling layer 1 of MTJ2 from SL1 to SL2 exceeds IC2, MTJ2 will flip to the parallel state (representing data 0); when the current passing through the spin-orbit coupling layer 1 of MTJ1 from SL2 to SL1 exceeds IC1, MTJ1 will flip to the antiparallel state (representing data 1); when the current passing through the spin-orbit coupling layer 1 of MTJ2 from SL2 to SL1 exceeds IC2, MTJ2 will flip to the antiparallel state (representing data 1).

[0060] 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.

[0061] If data needs to be written into two MTJs, first set WL to high level, turn on N1 and N2, connect BL1 to high level, connect BL2 to low level, and apply a current of magnitude IH. At this time, the same value is written into the two MTJs. If MTJ2 is in the same state as the target state, the writing ends; if it is different from the target state, apply a current of magnitude IL in the opposite direction to complete the writing of MTJ2.

[0062] If only writing into MTJ1 is needed, first set WL to high level, turn on N1 and N2, connect BL1 to high level, connect BL2 to low level, and apply a current of magnitude IH according to the target state to write the same value into the two MTJs. At this time, if MTJ2 is in the same state as the initial state, the writing ends; if it is different from the initial state, apply a current of magnitude IL in the opposite direction to write MTJ2 back to the initial state.

[0063] If only writing into MTJ2 is needed, first set WL to high level, turn on N1 and N2, connect BL1 to high level, connect BL2 to low level, and apply a current of magnitude IL according to the target state to write the required value into MTJ2.

[0064] If the original data in the storage cell is not considered, the general steps to write four kinds of data into the two MTJs are as follows: Step 0: WL is at high level, N1 and N2 are turned on, BL1 is connected to high level, and BL2 is connected to low level.

[0065] Step 1: Select the direction of the applied current according to the desired state of MTJ1, and the amplitude of the current is IH. Thus, the magnetization directions of both MTJ1 and MTJ2 are written as the desired state of MTJ1. If MTJ1 is in the same state as the target state of MTJ2, the writing operation ends. If MTJ1 and MTJ2 are in different target states, then go to Step 2.

[0066] Step 2: Apply a current in the opposite direction to that in Step 1, and the amplitude of the current is IL. Thus, the magnetization direction of MTJ2 is written as the desired state of MTJ2, and the writing operation ends.

[0067] The specific writing operation is as follows: Step 0: Set WL to high level, turn on N1 and N2, connect BL1 to high level, and connect BL2 to low level.

[0068] If the written data is 00: Step 1: Apply a current in the direction from SL1 to SL2 (SL12SL2) with an amplitude of IH, and the data 00 is written, and the writing operation ends.

[0069] If the written data is 01: Step 1: Apply a current in the direction from SL1 to SL2 (SL12SL2) with an amplitude of IH, write data 00, and continue the write operation.

[0070] Step 2: Apply a current in the direction from SL2 to SL1 (SL22SL1) with an amplitude of IL, write data 01, and end the write operation.

[0071] If the written data is 11: Step 1: Apply a current in the direction from SL2 to SL1 (SL22SL1) with an amplitude of IH, write data 11, and end the write operation.

[0072] If the written data is 01: Step 1: Apply a current in the direction from SL2 to SL1 (SL22SL1) with an amplitude of IH, write data 11, and continue the write operation.

[0073] Step 2: Apply a current in the direction from SL1 to SL2 (SL12SL2) with an amplitude of IL, write data 10, and end the write operation.

[0074] If considering the original data in the storage cell, the general steps to write four types of data to two MTJs are as follows: Step 0: Turn on N1 and N2 with WL at high level, connect BL1 to high level, and connect BL2 to low level.

[0075] Step 1: Read the original data in the storage cell. If the data to be written is the same as the original data, end the write operation; if the written data is different from the original data, go to Step 2.

[0076] Step 2: Keep WL at high level and turn on N1 and N2. Then, according to the Figure 5 shown state transition diagram, select the path with the minimum cost (such as minimum power consumption, shortest path) to write data.

[0077] During the read operation: Assume that the high and low resistance values of MTJ1 and MTJ2 are as shown in Table 1 respectively: Table 1

[0078] Then, the resistances of the four states of the storage cell from low to high are as shown in Table 2, where (A = 1 + TMR), and TMR is the magnetoresistance of the magnetic tunnel junction.

[0079] Table 2

[0080] To improve the read performance and reduce the probability of read failure, the standard deviation of each piece of data 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: Table 3

[0081] R_xx refers to the resistance value of two parallel MTJs in the corresponding state, and σ_xx refers to the total standard deviation in the read circuit in the corresponding state.

[0082] Among them, the k value means that the resistance of MTJ2 is k times that of MTJ1. To improve the read performance, the read failure probability can be calculated to make the read failure probability the lowest, thereby obtaining the k value.

[0083] The steps of reading are as follows: Step 0: When WL is at a high level, N1 and N2 are turned on. When REN is at a high level, BL1 and BL2 are short-circuited. At the same time, only BL1 is set to a high level. The read current flows through two parallel MTJs to generate a data voltage, and the corresponding reference resistance generates a reference voltage.

[0084] Step 1: Compare the data voltage with the reference voltage 1. If the data voltage is large, MTJ1 is in the high-resistance antiparallel state, and the data is 1X (X is 0 or 1); if the data voltage is small, MTJ1 is in the low-resistance parallel state, and the data is 0X.

[0085] Step 2: If the data is 1X, compare the data voltage with the reference voltage 2. If the data voltage is large, MTJ2 is in the high-resistance antiparallel state, and the data is 11; if the data voltage is small, MTJ2 is in the 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 large, MTJ2 is in the high-resistance antiparallel state, and the data is 01; if the data voltage is small, MTJ2 is in the low-resistance parallel state, and the data is 00.

[0086] 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 cube, an elliptical cylinder, etc. The bottom shape of at least one magnetic tunnel junction provided on the spin-orbit coupling layer 1, that is, the lower surface of the free layer 2 is coupled to the spin-orbit coupling layer 1.

[0087] Preferably, the spin-orbit coupling layer 1 can be selected as a rectangle, 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, that is, the 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 edges of the spin-orbit coupling layer 1. Among them, the spin-orbit coupling layer 1 is preferably selected as a heavy metal strip-shaped thin film or an antiferromagnetic strip-shaped thin film.

[0088] In a preferred embodiment, when the magnetic random access memory cell inputs current to the spin-orbit coupling layer 1 and the magnetic tunnel junction, the input can be achieved by providing electrodes 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 respectively provided on the two 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).

[0089] Preferably, the materials of the free layer 2 and the fixed layer 4 can be ferromagnetic metals, and the material of the barrier layer 3 can be an oxide. When the magnetic tunnel junction has perpendicular magnetic anisotropy, it means that the magnetization directions of the free layer 2 and the fixed layer 4 forming the magnetic tunnel junction are along the vertical direction. Among them, the ferromagnetic metal can be a mixed metal material formed by at least one of materials such as cobalt iron (CoFe), cobalt iron boron (CoFeB), or nickel iron (NiFe), and the proportions of the mixed metal materials can be the same or different. The oxide can be one of oxides such as magnesium oxide (MgO) or aluminum oxide (Al2O3), which is used to generate the tunneling magnetoresistance effect. In practical applications, other feasible materials can also be used for the ferromagnetic metal and the oxide, and the present invention does not limit this.

[0090] The free layer 2 of the magnetic tunnel junction is in contact and fixed with the spin-orbit coupling layer 1. The layers of the magnetic tunnel junction and the spin-orbit coupling layer 1 can be sequentially deposited on the substrate in order from bottom to top by traditional methods such as ion beam epitaxy, atomic layer deposition, or magnetron sputtering, and then multiple magnetic tunnel junctions can be prepared by traditional nano-device processing techniques such as photolithography and etching.

[0091] In a preferred embodiment, the spin-orbit coupling layer 1 is a spin-orbit coupling layer 1 composed of a heavy metal thin film, an antiferromagnetic thin film, or other materials. The heavy metal thin film or the antiferromagnetic thin film can be made rectangular, and its top area is preferably larger than the bottom area of the contour formed by all the magnetic tunnel junctions, so as to be able to provide one or more magnetic tunnel junctions, and the bottom shape of the magnetic tunnel junction is completely embedded in the top shape of the heavy metal thin film or the antiferromagnetic thin film. Preferably, the material of the spin-orbit coupling layer 1 can be selected from materials such as platinum (Pt), tantalum (Ta), or tungsten (W). In practical applications, the spin-orbit coupling layer 1 can also be formed by other feasible materials, and the present invention does not limit this.

[0092] Those skilled in the art can understand that the switching element in this embodiment can be a triode. In other embodiments, a diode can also be used. When implemented with a triode, an N-type triode or a P-type triode can be used. The high and low levels of various signals can achieve corresponding functions only in cooperation with the type of the triode. Those skilled in the art know that a low-level signal is required to turn on a P-type triode, and a high-level signal is required to turn on an N-type triode. Therefore, an N-type triode or a P-type triode is used and the level of the triode gate (control terminal) is set to achieve the corresponding conduction or disconnection function, so as to achieve the data reading purpose of the present invention. In the embodiment of the present invention, the control terminal of the triode is the gate, the first end can be the source, and the second end is the drain, or vice versa. The first end can be the drain and the second end is the source. The present invention does not make a limitation on this, and it can be reasonably selected according to the type of the triode.

[0093] In addition, the triode provided in the embodiment of the present invention can be a field-effect triode, which can be an enhancement-mode field-effect triode or a depletion-mode field-effect triode. The triode can adopt a low-temperature polysilicon TFT, which can reduce the manufacturing cost and product power consumption and has a faster electron mobility. An oxide semiconductor TFT can also be used.

[0094] In this embodiment, the magnetic tunnel junction includes a fixed layer 4 at the top, a free layer 2 in contact with the spin-orbit coupling layer 1, and a barrier layer 3 provided between the fixed layer 4 and the free layer 2. The magnetic tunnel junction is a three-layer structure and only includes one free layer 2. In other embodiments, the free layer 2 can be set to multiple, that is, two or more free layers 2. Then the magnetic tunnel junction includes a fixed layer 4 at the top, multiple free layers 2, and a barrier layer 3 provided between each adjacent two layers. The bottom free layer 2 is 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 unit structure can include a spin-orbit coupling layer 1, a second free layer, a barrier layer 3, a first free layer, a barrier layer 3, and a fixed layer 4 arranged in sequence on the spin-orbit coupling layer 1.

[0095] 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 storage units as described in the present invention arranged in an array.

[0096] Such as Figure 4As shown, the memory includes four magnetic random access memory cells arranged in a 2*2 array. Among them, the switching elements of each column of memory cells share the write control lines (WL0, WL1), the switching elements of each row of memory cells share the first write line (SL10, SL11) and the second write line (SL20, SL21), all memory cells share the read control line REN, and the switching elements of each row of memory cells share the first control line (BL10, BL20) and the second control line (BL11, BL21).

[0097] Since the principle of solving problems by this memory is similar to that of the above magnetic random access memory cells, the implementation of this memory can refer to the implementation of the above magnetic random access memory cells, which will not be elaborated here.

[0098] Magnetic random access memory includes permanent and non-permanent, removable and non-removable media. Information storage can be implemented by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of applications of magnetic random access memory 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 versatile disc (DVD), or other optical storage, magnetic cassette tapes, magnetic 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.

[0099] Based on the same principle, this embodiment also discloses a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. The processor and / or the memory includes the magnetic random access memory cells as described in this embodiment.

[0100] The magnetic random access memory cells illustrated in the above embodiments can be specifically arranged in a product device with 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 smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0101] In a typical example, the computer device specifically includes a memory, a processor, and a computer program stored on the memory and executable on the processor. The processor and / or the memory includes the magnetic random access memory cells as described in this embodiment.

[0102] Refer to the following Figure 6, which shows a schematic structural diagram of a computer device 600 suitable for implementing the embodiments of the present invention.

[0103] As Figure 6 shown, the computer device 600 includes a central processing unit (CPU) 601, which can perform various appropriate operations and processes according to the programs stored in the read-only memory (ROM) 602 or the programs loaded from the storage section 608 into the random access memory (RAM) 603. In the RAM 603, various programs and data required for the operation of the computer device 600 are also stored. The CPU 601, ROM 602, and RAM 603 are connected to each other via a bus 604. The input / output (I / O) interface 605 is also connected to the bus 604.

[0104] The following components are connected to the I / O interface 605: an input section 606 including a keyboard, a mouse, etc.; an output section 607 including, for example, a cathode ray tube (CRT), a liquid crystal display (LCD), etc. and speakers, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a LAN card, a modem, etc. 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. A removable medium 611, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 610 as needed so that the computer program read from it can be installed in the storage section 608 as needed.

[0105] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0106] These computer program instructions can 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 generate a manufactured article including instruction means, and the instruction means implements the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0107] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are executed on the computer or other programmable apparatus to produce a computer-implemented process, and thus the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one process Figure 1 one process or a plurality of processes and / or blocks Figure 1 steps of the functions specified in one block or a plurality of blocks.

[0108] It should also be noted that the term "comprising", "including" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, commodity or apparatus comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, commodity or apparatus. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, commodity or apparatus comprising said element.

[0109] Those skilled in the art will appreciate that the embodiments of the present invention may be provided as a method, system or computer program product. Therefore, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Moreover, the present invention may be implemented in the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0110] The present invention may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The present invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media including storage devices.

[0111] Each embodiment in this specification is described in a progressive manner, and the same or similar parts among the embodiments may be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system embodiments, since they are basically similar to method embodiments, they are described relatively simply, and the relevant parts may refer to the description of the method embodiments.

[0112] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall 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 disposed on the spin-orbit coupling layer, and a VCMA regulation module; The VCMA regulation module is configured 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 at least include a first magnetic tunnel junction and a second magnetic tunnel junction, and the cross-sectional size of the first magnetic tunnel junction in contact with the spin-orbit coupling layer is larger than the cross-sectional size 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, and 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; It further includes 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 includes a first switching element and a second switching element; The first end of the first switching element is connected to the first write line, and the second end is connected to the first input end of the spin-orbit coupling layer; The first end of the second switching element is connected to the second write line, and the 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 respectively connected to the tops of the first magnetic tunnel junction and the second magnetic tunnel junction.

2. The magnetic random access memory cell according to claim 1, wherein The VCMA regulation module is configured to input a low-level VCMA voltage to the corresponding magnetic tunnel junction to make the magnetic tunnel junction in a first perpendicular anisotropy state, and input a high-level VCMA voltage to the corresponding magnetic tunnel junction to make the magnetic tunnel junction 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; When the VCMA regulation module inputs a low-level VCMA voltage to the first magnetic tunnel junction, the critical switching current for the free layer of the first magnetic tunnel junction to flip is a first critical current value, and when the VCMA regulation module inputs a high-level VCMA voltage to the first magnetic tunnel junction, the critical switching current for the free layer of the first magnetic tunnel junction to flip is a second critical current value; When the VCMA regulation module inputs a low-level VCMA voltage to the second magnetic tunnel junction, the critical switching current for the free layer of the second magnetic tunnel junction to flip is a third critical current value, and when the VCMA regulation module inputs a high-level VCMA voltage to the second magnetic tunnel junction, the critical switching current for the free layer of the second magnetic tunnel junction to flip 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.

3. The magnetic random access memory cell according to claim 2, 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.

4. The magnetic random access memory cell according to claim 1, characterized in that The first magnetic tunnel junction and the second magnetic tunnel junction include a fixed layer, a barrier layer, and a free layer sequentially arranged 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.

5. The magnetic random access memory cell according to claim 1, characterized in that When the current input by 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 by 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 by 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 by 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.

6. The magnetic random access memory cell according to claim 1, wherein It further includes a third switching element and a read control line. The first end and the second end of the third switching element are respectively connected to the first control line and the second control line, and the control end of the third switching element is connected to the read control line.

7. A magnetic random access memory, characterized in that, It includes a plurality of magnetic random access memory cells arranged in an array as described in any one of claims 1-6.

8. A method for writing data into a magnetic random access memory cell according to any one of claims 1-6, characterized in that, It includes: Determine the spin-orbit torque current based on the data to be written and input the spin-orbit torque current into the spin-orbit coupling layer. Among them, if the data to be written is "00", the spin-orbit torque current is a write current in the first direction, and the current density of the write current is greater than the 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 the first direction and a second write current in the second direction input in sequence. The current density of the first write current is greater than the critical switching current of the first magnetic tunnel junction, and the current density of the second write current is greater than the critical switching current of the second magnetic tunnel junction and less than the 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 the second direction and a second write current in the first direction input in sequence. The current density of the first write current is greater than the critical switching current of the first magnetic tunnel junction, and the current density of the second write current is greater than the critical switching current of the second magnetic tunnel junction and less than the 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.

9. The data writing method according to claim 8, wherein When writing "00", input a high-level VCMA voltage to the first magnetic tunnel junction and the second magnetic tunnel junction, so that the critical switching current for the free layer of the first magnetic tunnel junction to flip is the second critical current value, the critical switching current for the free layer of the second magnetic tunnel junction to flip is the 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 writing "01", a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction. The critical switching current for the free layer of the first magnetic tunnel junction to flip is the second critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is the fourth critical current value. 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. The critical switching current for the free layer of the first magnetic tunnel junction to flip is the first critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is the fourth critical current value. 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 writing "10", a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction. The critical switching current for the free layer of the first magnetic tunnel junction to flip is the second critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is the fourth critical current value. 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. The critical switching current for the free layer of the first magnetic tunnel junction to flip is the first critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is the fourth critical current value. 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 writing "11", a high-level VCMA voltage is input to the first magnetic tunnel junction and the second magnetic tunnel junction. The critical switching current for the free layer of the first magnetic tunnel junction to flip is the second critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is the fourth critical current value. The current density of the write current in the second direction is greater than the second critical current value.

10. The data writing method according to claim 8, wherein The spin-orbit torque current input to the spin-orbit coupling layer determined based on the data to be written includes: 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 only writing the data "0" 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. The critical switching current for the free layer of the first magnetic tunnel junction to flip is the second critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to flip is the third critical current value. 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; When only inputting data "1" 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. The critical switching current for the free layer of the first magnetic tunnel junction to switch is the second critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to switch is the third critical current value. The current density of the write current in the second direction is greater than the second critical current value and less than the third critical current value; When only inputting data "1" 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. The critical switching current for the free layer of the first magnetic tunnel junction to switch is the first critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to switch is the fourth critical current value. The current density of the write current in the first direction is greater than the fourth critical current value and less than the first critical current value; When only inputting data "0" 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. The critical switching current for the free layer of the first magnetic tunnel junction to switch is the first critical current value, and the critical switching current for the free layer of the second magnetic tunnel junction to switch is the fourth critical current value. 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.

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