CN109256160B - Spin orbit torque magnetic memory reading method - Google Patents
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- CN109256160B CN109256160B CN201811066017.1A CN201811066017A CN109256160B CN 109256160 B CN109256160 B CN 109256160B CN 201811066017 A CN201811066017 A CN 201811066017A CN 109256160 B CN109256160 B CN 109256160B
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- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
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- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
- G11C11/161—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
Abstract
The invention discloses a method for reading a spin orbit torque magnetic memory, which comprises the following steps: s1, applying a reading signal to a spin-orbit torque magnetic memory data unit to be read, and recording a first data signal generated by the data unit; s2, applying an auxiliary signal to act on the heavy metal film of the data unit to make the data unit in a temporary stable state; s3, reading the information of the data unit according to the magnitude relation between the first data signal and the second data signal generated by the data unit in the transient state; s4, according to the read information of step S3, the data unit is restored from the temporary stable state to the state before reading. Compared with the traditional self-reference method, the method provided by the invention eliminates the influence of device process errors and ensures the reliability of data reading; the control complexity and the circuit structure are simplified; the device loss is reduced; the reading speed is faster.
Description
[ technical field ] A method for producing a semiconductor device
The invention belongs to the technical field of nonvolatile memories, and particularly relates to a method for reading a spin orbit torque magnetic memory.
[ background of the invention ]
Spin orbit torque magnetic tunnel junction (SOT-MTJ) is a resistive memory device based on tunneling magnetoresistance effect, and binary information is represented by the high and low resistance states, so that it can be used to construct a nonvolatile Spin orbit torque magnetic random access memory (SOT-MRAM). According to the difference between the direction of easy magnetization axis and the direction of film surface, the SOT-MTJ can be divided into two types: in-plane (In-plane) magnetic anisotropy SOT-MTJ (I-SOT-MTJ) and Perpendicular (Perpendicular) magnetic anisotropy SOT-MTJ (P-SOT-MTJ). P-SOT-MTJ is better than I-SOT-MTJ in storage density, write power consumption, thermal stability, etc. and thus has received much attention, and its structure and circuit symbols are shown in FIG. 1A and FIG. 1B, respectively. The P-SOT-MTJ can complete high-speed and reliable data writing operation through Spin-Hall effect (SHE), overcomes the problems of initial delay (Incubation delay) and barrier breakdown of the traditional Spin transfer torque magnetic tunnel junction (STT-MTJ), and simultaneously retains the advantages of non-volatility, radiation resistance, erasing resistance and the like of the STT-MTJ, so that the P-SOT-MTJ is expected to become a next-generation low-power-consumption storage unit.
The data unit of the SOT-MRAM consists of an SOT-MTJ and a corresponding access transistor, and the reading of data is realized by detecting the resistance value of the MTJ in the data unit. Existing P-SOT-MTJ reading methods generally fall into two categories: the first type judges the information of the data unit by applying the same current (or voltage) to the data unit and the reference unit and comparing the voltage value (or current value) generated by the data unit and the reference unit correspondingly; the second type performs self-reference reading by performing a read-reference write-compare read-rewrite operation on the same data unit. However, as the process size decreases, the process deviation increases, and the standard deviation of the resistance values of the memory cell and the reference cell increases, so that the reliability of the first type of reading method decreases; the second type of conventional self-referencing method has higher reliability than the first type of conventional self-referencing method, but because two write operations are required, higher read delay is caused and the device lifetime is seriously lost, and in addition, the operation Margin (Margin) of the read current in the "comparison and sensing" process is extremely limited, and the control difficulty is high. Both of these methods fail to meet the requirements for read performance at submicron dimensions.
[ summary of the invention ]
The invention discloses a method for reading a spin-orbit torque magnetic memory, aiming at the problem that the performances of reading reliability, speed, control complexity and the like mentioned in the background are difficult to be considered simultaneously. The method overcomes the defects of the prior art, utilizes the intrinsic property of the device to generate the self-reference signal, and has the advantages of high reliability, low control complexity, small device loss, high speed and the like.
The technical scheme of the invention is as follows: a spin orbit torque magnetic memory reading method, the method comprising the steps of:
s1, applying the reading signal to the spin-orbit torque magnetic memory data unit to be read, and recording a first data signal generated by the data unit;
when the reading signal is a current signal, the first data signal is a voltage signal, and the amplitude value of the first data signal can be recorded by the voltage sampling circuit; when the reading signal is a voltage signal, the first data signal is a current signal, and the amplitude of the current signal can be recorded by the current sampling circuit.
S2, applying an auxiliary signal to the heavy metal film 14 of the data unit to make the data unit in a temporary stable state;
the auxiliary signal is specifically: the direction and amplitude of the spin Hall effect current are fixed and unchangeable in the application process, so that the reading control complexity and the circuit structure can be simplified; the transient steady state is a state where the resistance of the data cell is temporarily stabilized at an intermediate resistance between its high and low resistance values.
S3, reading the information of the data unit according to the magnitude relation between the first data signal and the second data signal generated by the data unit in the transient state;
the second data signal is generated by the data unit in the transient state under the action of the same reading signal in the step S1, is the same type of electric signal as the first data signal, and can judge the magnitude relation of the amplitudes thereof through the comparison circuit;
if the second data signal is larger than the first data signal, judging that the data unit is in a low-resistance state; on the contrary, if the second data signal is smaller than the first data signal, the data unit is judged to be in a high impedance state; the low resistance state may represent the stored information as a "0" and the high resistance state may represent the stored information as a "1", or vice versa, i.e., the high resistance state may represent the stored information as a "0" and the low resistance state may represent the stored information as a "1".
S4, according to the read information of step S3, the data unit is restored from the temporary stable state to the state before reading.
The recovering the data unit from the transient state to the state before reading specifically includes:
s41, obtaining the read-out information of the data unit in the step S3;
s42, determining the Spin Transfer Torque (STT) current direction required to be applied for recovering data according to the read information of the data unit in the step S3; if the read information is in a low resistance state, the applied STT current direction ensures that the data unit is written into the low resistance state, namely the magnetization directions of two ferromagnetic layers of the magnetic tunnel junction are parallel to each other; if the read information is in a high resistance state, the applied STT current direction ensures that the data unit is written into the high resistance state, namely the magnetization directions of two ferromagnetic layers of the magnetic tunnel junction are antiparallel to each other;
s43, removing the auxiliary signal applied in step S2, and applying the recovery current with the determined direction in step S42 to recover the data unit from the temporary steady state to the state before reading.
The spin orbit torque magnetic memory reading method has the advantages that:
(1) the invention utilizes the intrinsic property of the device to generate the self-reference signal, thereby eliminating the influence of the process error of the device and ensuring the reliability of data reading.
(2) Compared with the traditional self-reference method, the method has the advantages that the current (voltage) can be read twice by adopting the same amplitude, the accurate adjustment of the amplitude is not needed, and the control complexity and the circuit structure are simplified.
(3) Compared with the traditional self-reference method, the method only performs once recovery writing operation in the whole reading process, and the adopted auxiliary signal acts on the heavy metal film without passing through the device, so that the device loss is reduced.
(4) Compared with the traditional self-reference method, the self-reference method has the advantages that the auxiliary signal is used for inducing the spin orbit torque, the writing efficiency is higher than that of other nonvolatile resistance change devices, and the generation of the self-reference signal and the recovery of data unit information can be rapidly completed, so that the reading speed is higher.
[ description of the drawings ]
FIG. 1A is a schematic structural diagram of a P-SOT-MTJ device.
FIG. 1B is a schematic diagram of a P-SOT-MTJ circuit.
FIG. 2A is a diagram illustrating the magnetization direction definition of the MTJ free layer.
FIG. 2B is a schematic diagram of the spin Hall effect current.
FIG. 3 is a schematic diagram of a spin-orbit torque magnetic memory reading method according to the present invention.
FIG. 4 shows an embodiment of a method for reading a spin-orbit torque magnetic memory according to the present invention.
Fig. 5 is a schematic circuit diagram for implementing the specific embodiment according to the embodiment of the present invention.
Wherein, the parameters in the graph are defined as:
11: a first ferromagnetic layer;
12: a barrier layer;
13: a second ferromagnetic layer;
14: a heavy metal film;
21: a fixed layer magnetization direction;
22: a free layer magnetization direction;
23: electrons that spin upward;
24: electrons with spin-down;
41: a peripheral read control module;
42: a storage array;
43: a signal sampling module;
44: a signal decision module;
45: a data recovery module;
T1-T3: a first electrode, a second electrode and a third electrode in sequence;
SHE: spin Hall Effect, which is the abbreviation of Spin-Hall Effect;
STT: spin Transfer Torque, short for Spin Transfer Torque;
θ: a polar angle of the magnetization direction of the free layer in the coordinate axis;
σ: an electron spin unit vector injected into the free layer due to the spin hall effect;
SR: a read signal generated by the selected data cell;
Sd_1: obtaining a signal after the first sampling;
Sd_2: obtaining a signal after the second sampling;
BL: bit lines, which are short for Bit lines;
WL: word Line, short for Word Line;
TG1-TG 8: sequentially comprises Transmission gates 1-8, and TG is the abbreviation of Transmission Gate;
Iread: a read current flowing through the data cell;
C1: for sampling SRA first capacitance for the signal;
C2: for sampling SRA second capacitance for the signal;
VDD: a power supply voltage;
Vout1: output signal of one end of signal decision module, and Vout2Mutually logic high and low levels;
Vout2: output signal of one end of signal decision module, and Vout1Mutually logic high and low levels;
[ detailed description ] embodiments
The essential features of the invention are further explained with reference to the drawings. Detailed exemplary embodiments are disclosed herein with specific structural and functional details representative of the purposes of describing the exemplary embodiments only, and thus the present invention may be embodied in many alternate forms and should not be construed as limited to only the exemplary embodiments set forth herein but rather as covering all changes, equivalents, and alternatives falling within the scope of the present invention. Additionally, well-known elements, devices and sub-circuits of the invention will not be described in detail or will be omitted so as not to obscure the relevant details of the embodiments of the invention.
FIG. 1A is a schematic structural diagram of a P-SOT-MTJ device; FIG. 1B is a schematic diagram of a P-SOT-MTJ circuit.
As shown in FIG. 1A, the P-SOT-MTJ device is composed of four layers from top to bottom, which are: a first ferromagnetic layer 11, a barrier layer 12, a second ferromagnetic layer 13, and a heavy metal film 14. The upper end of the first ferromagnetic layer 11 is plated with a first electrode T1, and both ends of the heavy metal film 14 are plated with a second electrode T2 and a third electrode T3, respectively. The first ferromagnetic layer 11, the barrier layer 12, and the second ferromagnetic layer 13 constitute an MTJ structure, which is fabricated over the heavy metal film 14. Depending on the direction of the easy axes of the two ferromagnetic layers, MTJs can be classified into in-plane magnetic anisotropy and perpendicular magnetic anisotropy. In fig. 1A, the easy magnetization axis direction is perpendicular to the film surface, and therefore, it is a perpendicular magnetic anisotropy MTJ. In which the magnetization direction of the first ferromagnetic layer 11 is constant, called the pinned layer; the magnetization direction of the second ferromagnetic layer 13 can assume both orientations parallel or antiparallel to the first ferromagnetic layer 11, referred to as the free layer. More specifically, when the fixed and free layer magnetization directions are parallel, the MTJ exhibits a low resistance value; when antiparallel, the MTJ exhibits a high resistance and thus can store binary information.
The P-SOT-MTJ achieves the resistance state transition by spin-orbit torque, wherein a specific implementation of pure electricity is to use Spin Hall Effect (SHE) current flowing through the heavy metal film 14 and Spin Transfer Torque (STT) current flowing through the MTJ to jointly complete the write operation, as shown in fig. 1B. The SHE current can induce spin orbit torque, and the magnetization direction of the MTJ free layer is rapidly inverted from the perpendicular direction to the in-plane direction at the initial stage of writing. However, the SOT alone cannot achieve a definite inversion because the two states vertically up and vertically down are equivalent in the in-plane direction, and thus after the magnetization direction of the free layer is inverted to the in-plane direction, the SHE current needs to be removed, and the final inversion direction is determined by the STT current. In fig. 1B, assuming that the magnetization direction of the pinned layer is upward perpendicular to the heavy metal film 14, when SHE current flows from the T2 end to the T3 end (or from the T3 end to the T2 end), if STT current flows from the T1 end to the T2 end (or from the T1 end to the T3 end), MTJ becomes a high resistance value; if the STT current flows from terminal T2 to terminal T1 (or from terminal T3 to terminal T1), the MTJ becomes low resistance.
FIG. 2A is a diagram illustrating the magnetization direction definition of the MTJ free layer.
Without loss of generality, assuming that the magnetization direction 21 of the fixed layer is positive along the z-axis of the coordinate axis, the polar angle and the azimuthal angle of the magnetization direction 22 of the free layer and the coordinate axis are recorded as θ and
when theta is 0 deg., the MTJ has low resistance and uses RPRepresents; when theta is 180 deg., the MTJ has high resistance and uses RAPExpressed, the Tunneling Magnetoresistance (TMR) of the MTJ can be calculated by the following formula,
in particular, if the TMR value at zero bias is denoted as TMR0Then the actual resistance R of the MTJMTJCan be calculated as follows:
wherein V represents the MTJ bias voltage, VhIndicating that TMR value becomes TMR0Half the bias voltage. The above equation shows the actual resistance R of the MTJMTJIs a function of the bias voltage V and the polar angle theta.
FIG. 2B is a schematic diagram of the effect of spin Hall effect current.
The SHE current can be used not only for write operations but also as an auxiliary signal during read. As shown in fig. 2B, when the SHE current flows through the heavy metal thin film 14, the spin-up electrons 23 and the spin-down electrons 24 are gathered equally along both sides of the z-axis, causing strong spin-orbit coupling of the heavy metal material, inducing spin-orbit torque, and rapidly reversing the magnetization direction of the MTJ free layer from the perpendicular direction to the in-plane direction (i.e., θ ═ 90 °). Then, if SHE current is continuously applied, the magnetization direction of the free layer can be temporarily maintained in the in-plane direction, and according to the formula (2), the resistance value of the MTJ is about the middle resistance value between the high and low resistance values, which can be used as the reference resistance value for data reading operation. By utilizing the intrinsic property, high-reliability and high-speed data reading can be realized by generating a self-reference signal by the device.
FIG. 3 is a schematic diagram of a spin-orbit torque magnetic memory reading method according to the present invention.
In step S1, a read signal is applied to a spin-orbit torque magnetic memory data cell to be read, and a first data signal generated by the data cell is recorded.
In this step, when the read signal is a current signal, the first data signal is a voltage signal, and the amplitude of the voltage signal can be recorded by the voltage sampling circuit; when the reading signal is a voltage signal, the first data signal is a current signal, and the amplitude of the current signal can be recorded by the current sampling circuit.
In step S2, an auxiliary signal is applied to the heavy metal film 14 of the data cell to make the data cell in a temporary steady state;
in this step, the auxiliary signal is specifically: the direction and amplitude of the spin Hall effect current are fixed and unchangeable in the application process, so that the reading control complexity and the circuit structure can be simplified; the transient steady state is a state where the resistance of the data cell is temporarily stabilized at an intermediate resistance between its high and low resistance values.
In step S3, reading information of the data unit according to the magnitude relationship between the first data signal and the second data signal generated by the data unit in the transient state;
in this step, the second data signal is generated by the data unit in the transient state under the action of the same reading signal in step S1, and is the same type of electrical signal as the first data signal, and the magnitude relationship between them can be judged by the comparison circuit;
if the second data signal is larger than the first data signal, judging that the data unit is in a low-resistance state; on the contrary, if the second data signal is smaller than the first data signal, the data unit is judged to be in a high impedance state; a low resistance state may represent stored information as a "0" and a high resistance state may represent stored information as a "1", or vice versa.
In step S4, the data unit is restored from the transient state to the state before reading in accordance with the read information of step S3.
In this step, the recovering the data unit from the transient and stable state to the state before reading specifically includes:
s41, obtaining the read-out information of the data unit in the step S3;
s42, determining the Spin Transfer Torque (STT) current direction required to be applied for recovering data according to the read information of the data unit in the step S3; if the read information is in a low resistance state, the applied STT current direction ensures that the data unit is written into the low resistance state, namely the magnetization directions of two ferromagnetic layers of the magnetic tunnel junction are parallel to each other; if the read information is in a high resistance state, the direction of the applied current should ensure that the data cell is written in the high resistance state, i.e. the magnetization directions of the two ferromagnetic layers of the magnetic tunnel junction are anti-parallel to each other;
s43, removing the auxiliary signal applied in step S2, and applying the recovery current with the determined direction in step S42 to recover the data unit from the temporary steady state to the state before reading.
In the reading method, under the action of an auxiliary signal such as spin Hall effect current, the intrinsic property of the device is utilized to generate a self-reference signal, so that the speed can reach subnanosecond level, the influence of the process error of the device is eliminated, and the reading reliability is ensured. Compared with the traditional self-reference method, on one hand, the auxiliary signal adopted by the method acts on the heavy metal film 14 without passing through the device, so that the loss of the device is reduced; on the other hand, the whole reading process of 'steady state-transient steady state-steady state' is equivalent to one-time writing operation, so that the speed is higher, the loss is lower, and the power consumption is smaller.
FIG. 4 shows an embodiment of a method for reading a spin-orbit torque magnetic memory according to the present invention.
The reading module of the spin-orbit torque magnetic memory of the embodiment is composed of a peripheral reading control module 41, a memory array 42, a signal sampling module 43, a signal decision module 44 and a data recovery module 45. The position connection relationship and the signal trend between the two are as follows: the peripheral reading control module 41 is connected with the other modules and is used for controlling the whole reading process and providing a reading signal and an auxiliary signal; the storage array 42 is connected with the input end of the signal sampling module 43 and provides a data signal generated under the action of a reading signal; the output end of the signal sampling module 43 is connected with the input end of the signal judging module 44, and is used for sampling data signals and outputting a first data signal and a second data signal generated before and after the auxiliary signal is applied; the output end of the signal judgment module 44 is connected with the input end of the data recovery module 45, and compares and judges the magnitude relation between the first data signal and the second data signal to output data read information; the output end of the data recovery module 45 is connected with the storage array 42, and according to the read information, the corresponding data unit is recovered from the temporary stable state to the state before reading.
Fig. 5 is a schematic circuit diagram for implementing the specific embodiment according to the embodiment of the present invention.
The circuit has the same structure as that of fig. 4. Wherein, the peripheral read control module 41 provides each module control signal, read signal IreadAnd an auxiliary signal SHE current; the memory array 42 is accessed by m x n data elements and correspondingThe transistor is formed, and a cell to be read can be selected through a bit line BL and a word line WL; the signal sampling module 43 samples the data signal S before and after applying the auxiliary signalRAnd obtain a first data signal Sd_1And a second data signal Sd_2(ii) a The signal decision module 44 receives Sd_1And Sd_2Comparing and judging their magnitudes and amplifying them to a logic level, and outputting a read result V complementarilyout1And Vout2(ii) a Data recovery module 45 receives Vout1And Vout2And generating a recovery current according to the read information, and recovering the data unit from the transient state to the state before reading through the recovery current after removing the auxiliary signal SHE current.
More specifically, the data reading process according to the embodiment of the present invention can be divided into the following four steps:
(1) under the control of the peripheral read control module 41, the read signal I is transmittedreadThe signal sampling module 43 is used for sampling the data voltage signal S of the selected spin orbit torque magnetic memory data unit in the memory array 42RAnd recorded as the first data signal Sd_1。
(2) The current of the auxiliary signal SHE is applied to the heavy metal film 14 of the data unit, so that the data unit is in a temporary stable state. Reading the signal S due to the change of the resistance of the data cellRWill change accordingly.
(3) At the same read current IreadNext, the signal sampling module 43 samples the changed SRIs denoted as a second data signal Sd_2And then S isd_1And Sd_2Output to the signal decision module 44; the signal decision module 44 compares Sd_1And Sd_2And amplifying the data cell size relationship to a logic level, and reading out the information of the data cell; if Sd_2Greater than Sd_1Judging that the data unit is in a low resistance state and the stored information is logic '0'; if Sd_2Less than Sd_1The data unit is judged to be in a high resistance state, and the stored information is logic '1'.
(4) The data recovery module 45 acquires the read information; determining the STT current direction of the recovery data according to the read information; if the read information is in a low resistance state, the STT current direction is a direction for writing the data unit into a parallel state; if the read information is in a high impedance state, the STT current direction is the direction for writing the data unit into an anti-parallel state; and then removing the auxiliary signal SHE current, and applying STT current in a determined direction to restore the data unit from the transient steady state to the state before reading.
It should be understood that the specific circuits described above and shown in fig. 5 are only a preferred embodiment of the present invention, and that numerous modifications and variations could be made in accordance with the principles of the present invention by those skilled in the art without the use of inventive faculty. Therefore, any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A spin orbit torque magnetic memory reading method, characterized by: the method comprises the following steps:
s1, applying a reading signal to a spin-orbit torque magnetic memory data unit to be read, and recording a first data signal generated by the data unit;
s2, applying an auxiliary signal to act on the heavy metal film of the data unit to make the data unit in a temporary stable state;
s3, reading the information of the data unit according to the magnitude relation between the first data signal and the second data signal generated by the data unit in the transient state; if the second data signal is larger than the first data signal, judging that the data unit is in a low-resistance state; on the contrary, if the second data signal is smaller than the first data signal, the data unit is judged to be in a high impedance state; the low resistance state may represent the stored information as a "0" and the high resistance state may represent the stored information as a "1", or vice versa, i.e., the high resistance state may represent the stored information as a "0" and the low resistance state may represent the stored information as a "1";
s4, according to the read information of step S3, the data unit is restored from the temporary stable state to the state before reading;
the auxiliary signal is specifically: a spin hall effect current whose direction and amplitude are fixed and invariant during application;
the transient state refers to the state that the resistance value of the data unit is temporarily stabilized at the middle resistance value between the high resistance value and the low resistance value;
the second data signal is generated by the data unit in the transient state under the action of the same reading signal in step S1, and is the same type of electric signal as the first data signal, and the magnitude relation of the amplitudes is judged through the comparison circuit.
2. A spin orbit torque magnetic memory reading method according to claim 1, wherein: in step S4, the step of restoring the data unit from the transient state to the state before reading includes:
s41, obtaining the read-out information of the data unit in the step S3;
s42, determining the direction of the spin transfer torque current required to restore the data according to the read information of the data unit in the step S3; if the read information is in a low resistance state, the direction of the applied spin transfer torque current should ensure that the data unit is written into the low resistance state, namely the magnetization directions of two ferromagnetic layers of the magnetic tunnel junction are parallel to each other; if the read information is in a high resistance state, the direction of the applied spin transfer torque current should ensure that the data unit is written into the high resistance state, i.e. the magnetization directions of the two ferromagnetic layers of the magnetic tunnel junction are antiparallel to each other;
s43, removing the auxiliary signal applied in step S2, and applying the recovery current with the determined direction in step S42 to recover the data unit from the temporary steady state to the state before reading.
3. A spin orbit torque magnetic memory reading method according to claim 1 or 2, wherein: the spin orbit torque magnetic memory reading module consists of a peripheral reading control module, a memory array, a signal sampling module, a signal judgment module and a data recovery module; the position connection relationship and the signal trend between the two are as follows: the peripheral reading control module is connected with the other modules and is used for controlling the whole reading process and providing a reading signal and an auxiliary signal; the storage array is connected with the input end of the signal sampling module and provides a data signal generated under the action of a reading signal; the output end of the signal sampling module is connected with the input end of the signal judging module and is used for sampling data signals and outputting a first data signal and a second data signal which are generated before and after the auxiliary signal is applied; the output end of the signal judgment module is connected with the input end of the data recovery module, the magnitude relation between the first data signal and the second data signal is compared and judged, and data read-out information is output; the output end of the data recovery module is connected with the storage array, and the corresponding data unit is recovered from the temporary stable state to the state before reading according to the read information.
4. A spin orbit torque magnetic memory reading method according to claim 3, wherein: the peripheral reading control module provides control signals of each module and a reading signal IreadAnd an auxiliary signal SHE current; the memory array is composed of m × n data units and corresponding access transistors, and the unit to be read is selected through a bit line BL and a word line WL; the signal sampling module samples the data signal S before and after applying the auxiliary signalRAnd obtain a first data signal Sd_1And a second data signal Sd_2(ii) a The signal decision module 44 receives Sd_1And Sd_2Comparing and judging their magnitudes and amplifying them to a logic level, and outputting a read result V complementarilyout1And Vout2(ii) a Data recovery module receives Vout1And Vout2And generating a recovery current according to the read information, and recovering the data unit from the transient state to the state before reading through the recovery current after removing the auxiliary signal SHE current.
5. A spin-orbit torque magnetic memory reading method according to claim 4, characterized in that: the data reading process is divided into the following four steps:
(1) under the control of the peripheral reading control module, the reading signal I is transmitted to the peripheral reading control modulereadActing on a selected spin orbit torque magnetic memory data unit in the memory array, the signal sampling module samples the data voltage signal S at the momentRAnd recorded as the first data signal Sd_1；
(2) Applying auxiliary signal SHEThe flow acts on the heavy metal film of the data unit to make the data unit in a temporary stable state; reading the signal S due to the change of the resistance of the data cellRWill change accordingly;
(3) at the same read current IreadNext, the signal sampling module samples the changed SRIs denoted as a second data signal Sd_2And then S isd_1And Sd_2Outputting the signal to a signal judgment module; signal decision module comparison Sd_1And Sd_2Amplifying the data unit to a logic level, and reading out the information of the data unit; if Sd_2Greater than Sd_1Judging that the data unit is in a low resistance state and the stored information is logic '0'; if Sd_2Less than Sd_1Judging that the data unit is in a high resistance state, and storing the information to be logic '1';
(4) the data recovery module acquires read information; determining STT current direction of recovery data according to the read information; if the read information is in a low resistance state, the STT current direction is a direction for writing the data unit into a parallel state; if the read information is in a high resistance state, the STT current direction is a direction for writing the data unit into an anti-parallel state; and then removing the auxiliary signal SHE current, and applying STT current in a determined direction to restore the data unit from the transient steady state to the state before reading.
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| CN110427170B (en) * | 2019-07-05 | 2021-05-25 | 北京航空航天大学 | Full adder based on spin orbit torque |
| CN110391331B (en) * | 2019-07-05 | 2021-03-09 | 北京航空航天大学 | Magnetic analog-digital converter |
| CN112447250B (en) * | 2019-08-30 | 2022-09-27 | 中电海康集团有限公司 | Test structure and test method |
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