Magnetic tunnel junction structure, storage unit and writing and reading method thereof

Abstract

The invention discloses a magnetic tunnel junction structure, a storage unit and a writing and reading method thereof. The magnetic tunnel junction structure comprises a conductive layer; the at least two magnetic tunnel junction units are located on the surface of the conducting layer, the at least two magnetic tunnel junction units are arranged in the first direction, and each magnetic tunnel junction unit comprises a free layer located on the surface of the conducting layer, a barrier layer located on the surface of the free layer and a reference layer located on the surface of the barrier layer; and operation currents of different magnetic tunnel junction units are different. The at least two magnetic tunnel junction units are located on the same conductive layer, so that the density of the magnetic tunnel junction units is increased, the area of circuit design is reduced, and the circuit integration level is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a magnetic tunnel junction structure, a storage unit and a writing and reading method thereof. Background Art

[0002] MRAM is a non-volatile magnetic random access memory. It has the high-speed read and write capabilities of static random access memory and the high integration of dynamic random access memory, and can basically be rewritten infinitely. The traditional MRAM cell includes MOS tube and magnetic tunnel junction (MTJ), among which MOS tube plays the role of providing write current.

[0003] In the prior art, two transistors are used in the spin orbit torque magnetic random access memory (SOT-MRAM) to perform write and read operations respectively. However, the two transistors occupy a larger area in the memory cell, which is not conducive to the integration of the memory cell. In addition, in the existing solution, the two transistors can only perform write and read operations on one magnetic tunnel junction cell, which reduces the storage efficiency. Summary of the invention

[0004] The technical problem solved by the present invention is that the integration of storage units is low and the storage efficiency is reduced.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a magnetic tunnel junction structure, including: a conductive layer; at least two magnetic tunnel junction units located on the surface of the conductive layer, the at least two magnetic tunnel junction units are arranged along a first direction, each of the magnetic tunnel junction units includes a free layer located on the surface of the conductive layer, a barrier layer located on the surface of the free layer, and a reference layer located on the surface of the barrier layer, and the operating currents of different magnetic tunnel junction units are different.

[0006] Optionally, the magnetic tunnel junction units are arranged along a first direction, and different magnetic tunnel junction units have different widths in a second direction, the second direction is parallel to the surface of the conductive layer, and the second direction is perpendicular to the first direction.

[0007] Optionally, widths of the at least two magnetic tunnel junction units increase one by one along the first direction, and operating currents of the at least two magnetic tunnel junction units increase one by one along the first direction.

[0008] Optionally, the conductive layer includes a plurality of device regions, each magnetic tunnel junction unit is located on a surface of a device region, and there is a preset size difference between a width of the device region in the second direction and a width of the magnetic tunnel junction unit.

[0009] Optionally, the material of the conductive layer is a combination of one or more of platinum, tantalum and tungsten.

[0010] Correspondingly, an embodiment of the present invention further provides a method for forming the above magnetic tunnel junction structure.

[0011] Correspondingly, an embodiment of the present invention also provides a storage unit, comprising: a conductive layer, the conductive layer comprising a first end and a second end; N magnetic tunnel junction units, each of the magnetic tunnel junction units comprising: a free layer electrode and a reference layer electrode, the free layer electrodes of the N magnetic tunnel junction units are electrically connected to the conductive layer, and the operating currents of the N magnetic tunnel junction units are all different, wherein N>1, and N is a positive integer; a first source line; a MOS tube, one of the source or drain of the MOS tube is connected to the first end of the conductive layer, and the other source or drain of the MOS tube is connected to the first source line; a second source line, the second source line is connected to the second end of the conductive layer.

[0012] Optionally, the storage unit further includes: a word line, to which the gate of the MOS tube is connected; and N bit lines, to which the reference layer electrodes of the N magnetic tunnel junction units are connected one-to-one.

[0013] Optionally, the N magnetic tunnel junction units are arranged along a first direction, and the N magnetic tunnel junction units have different widths in a second direction, the second direction is parallel to the surface of the conductive layer, and the second direction is perpendicular to the first direction.

[0014] Optionally, the width of the magnetic tunnel junction unit increases along a first direction, and the operating currents corresponding to the N magnetic tunnel junction units increase along the first direction.

[0015] Optionally, the N magnetic tunnel junction units increase in geometric proportion along the first direction, and the operating currents corresponding to the N magnetic tunnel junction units increase in geometric proportion along the first direction.

[0016] Optionally, the conductive layer includes a plurality of device regions, each magnetic tunnel junction unit is located on a surface of a device region, and there is a preset size difference between a width of the device region in the second direction and a width of the magnetic tunnel junction unit.

[0017] Optionally, the MOS tube includes an NMOS tube or a PMOS tube.

[0018] Optionally, when the MOS tube includes a PMOS tube, a source of the PMOS tube is connected to the first source line, and a drain of the PMOS tube is connected to the first end of the conductive layer.

[0019] Optionally, when the MOS tube includes an NMOS tube, the drain of the NMOS tube is connected to the first source line, and the source of the NMOS tube is connected to the first end of the conductive layer.

[0020] Optionally, the storage unit further includes N diodes, anodes of the N diodes are connected to the reference layer electrodes of the N magnetic tunnel junction units in a one-to-one correspondence, and cathodes of the N diodes are all connected to the word line.

[0021] Optionally, the N magnetic tunnel junction units include a first magnetic tunnel junction unit to an Nth magnetic tunnel junction unit arranged from the first end to the second end.

[0022] Optionally, the storage unit also includes: a write operation unit, which is used to: put the MOS tube into a conductive state; apply a first level to the first end of the conductive layer, and apply a second level to the second end of the conductive layer, the first level is opposite to the second level, and the conductive layer generates a write current Iwrite to write data to N magnetic tunnel junction units.

[0023] Optionally, writing data to the N magnetic tunnel junction units includes: when the current value of the write current Iwrite is between the operating current Ii of the i-th magnetic tunnel junction unit and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit, the first magnetic tunnel junction unit to the i-th magnetic tunnel junction unit are in a first resistance state, and the i+1-th magnetic tunnel junction unit to the N-th magnetic tunnel junction unit are in a second resistance state, wherein 1≤i≤N-1, i is a positive integer, and the first resistance state and the second resistance state are opposite.

[0024] Optionally, the storage unit also includes: a read operation unit, which is used to: put the MOS tube in a cut-off state and apply a first level to the second end of the conductive layer; obtain a read current Iread flowing through the reference layer electrode of the N magnetic tunnel junction units, and read the write data in the N magnetic tunnel junction units.

[0025] Optionally, reading the write data in the N magnetic tunnel junction units includes: when the current value of the read current Iread is between the operating current Ii of the i-th magnetic tunnel junction unit and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit, reading the write data in the N magnetic tunnel junction units according to the first resistance state of the first magnetic tunnel junction unit to the i-th magnetic tunnel junction unit and the second resistance state of the i+1-th magnetic tunnel junction unit to the N-th magnetic tunnel junction unit, wherein 1≤i≤N-1, i is a positive integer, and the write data represented by the first resistance state and the second resistance state are opposite.

[0026] Correspondingly, an embodiment of the present invention further provides a memory, comprising a plurality of the above-mentioned storage units.

[0027] Correspondingly, an embodiment of the present invention also provides a writing method for a storage unit, comprising: putting the MOS tube in a conducting state; applying a first level to a first end of a conductive layer, applying a second level to a second end of the conductive layer, the first level is opposite to the second level, the conductive layer generates a writing current Iwrite, and writing data to N magnetic tunnel junction units, wherein N>1, and N is a positive integer.

[0028] Optionally, the N magnetic tunnel junction units include a first magnetic tunnel junction unit to an Nth magnetic tunnel junction unit arranged from the first end to the second end.

[0029] Optionally, writing data to the N magnetic tunnel junction units includes: when the current value of the write current Iwrite is between the operating current Ii of the i-th magnetic tunnel junction unit and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit, the first magnetic tunnel junction unit to the i-th magnetic tunnel junction unit are in a first resistance state, and the i+1-th magnetic tunnel junction unit to the N-th magnetic tunnel junction unit are in a second resistance state, wherein 1≤i≤N-1, i is a positive integer, and the first resistance state and the second resistance state are opposite.

[0030] Correspondingly, an embodiment of the present invention also provides a method for reading a storage unit, comprising: putting the MOS tube in a cut-off state, applying a first level to the second end of the conductive layer; obtaining a read current Iread flowing through the reference layer electrode of the N magnetic tunnel junction units, and reading the write data in the N magnetic tunnel junction units, wherein N>1 and N is a positive integer.

[0031] Optionally, the N magnetic tunnel junction units include a first magnetic tunnel junction unit to an Nth magnetic tunnel junction unit arranged from the first end to the second end.

[0032] Optionally, when the current value of the read current Iread is between the operating current Ii of the i-th magnetic tunnel junction unit and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit, the write data in the N magnetic tunnel junction units are read according to the first resistance state of the first magnetic tunnel junction unit to the i-th magnetic tunnel junction unit and the second resistance state of the i+1-th magnetic tunnel junction unit to the N-th magnetic tunnel junction unit, where 1≤i≤N-1, i is a positive integer, and the write data represented by the first resistance state and the second resistance state are opposite.

[0033] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0034] The magnetic tunnel junction structure provided by the technical solution of the present invention, wherein the at least two magnetic tunnel junction units are located on the same conductive layer, increases the density of the magnetic tunnel junction units, reduces the area of ​​circuit design, improves the circuit integration, and the operating currents of the at least two magnetic tunnel junction units are different, so that the conductive layer can simultaneously control the storage states of different magnetic tunnel junction units, thereby achieving an improvement in storage efficiency.

[0035] Furthermore, in the technical solution of the present invention, the area of ​​the storage unit is reduced by setting the width of the magnetic tunnel junction unit to different widths, and the operating currents of the magnetic tunnel junction units of different widths are different. By controlling the size of the write current or the read current, the write operation or the read operation on different magnetic tunnel junction units is controlled, thereby achieving storage flexibility.

[0036] Furthermore, in the technical solution of the present invention, there is a preset size difference between the width of the conductive layer and the width of the magnetic tunnel junction unit, which reduces the size of the conductive layer in the second direction, thereby reducing the area of ​​the storage unit.

[0037] In the method for forming a magnetic tunnel junction structure provided by the technical solution of the present invention, at least two magnetic tunnel junction units are formed on a conductive layer, which increases the density of the magnetic tunnel junction units, reduces the area of ​​circuit design, and improves the circuit integration. In addition, the operating currents of at least two magnetic tunnel junction units are different, so that the conductive layer can simultaneously control the storage states of different magnetic tunnel junction units, thereby achieving an improvement in storage efficiency.

[0038] In the storage unit provided by the technical solution of the present invention, a MOS tube is connected to N magnetic tunnel junction units, which increases the density of the magnetic tunnel junction units, reduces the area of ​​circuit design, and improves the circuit integration. The N magnetic tunnel junction units are connected to a conductive layer at the same time, so that one MOS tube can provide write current for the N magnetic tunnel junction units at the same time, thereby improving the storage efficiency.

[0039] Furthermore, in the technical solution of the present invention, the area of ​​the storage unit is reduced by setting the width of the magnetic tunnel junction unit to different widths, and the operating currents of the magnetic tunnel junction units of different widths are different. By controlling the size of the write current or the read current, the write operation or the read operation on different magnetic tunnel junction units is controlled, thereby achieving storage flexibility.

[0040] Furthermore, in the technical solution of the present invention, diodes are connected in series with the magnetic tunnel junction units to block the reverse current, so that the current direction is fixed to avoid interference between the write operation and the read operation, and the area of ​​the diode is small, thereby reducing the area of ​​the storage unit.

[0041] In the writing method of the storage unit provided by the technical solution of the present invention, when the MOS tube is in the on state, a writing current is generated in the conductive layer, and N magnetic tunnel junction units are electrically connected to the conductive layer, so that one MOS tube can provide writing current for N magnetic tunnel junction units at the same time, thereby realizing the improvement of storage efficiency.

[0042] Furthermore, in the technical solution of the present invention, different storage states of the N magnetic tunnel junction units are controlled according to the operating current and the write current of the N magnetic tunnel junction units, thereby improving the storage flexibility and storage efficiency.

[0043] In the storage unit reading method provided by the technical solution of the present invention, when the MOS tube is in a conduction-off state, a reading current is generated in N magnetic tunnel junction units, and the reading current flowing through the N magnetic tunnel junction units is obtained, so that the storage states of the N magnetic tunnel junction units can be read simultaneously, thereby improving the storage efficiency.

[0044] Furthermore, in the technical solution of the present invention, different storage states on the N magnetic tunnel junction units are read according to the operating current and the reading current of the N magnetic tunnel junction units, thereby improving the storage flexibility and storage efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of a magnetic tunnel junction structure.

[0046] Figure 2 It is a structural diagram of a storage unit.

[0047] Figure 3 Schematic diagram of the magnetic tunnel junction structure in an embodiment of the present invention Figure 1 .

[0048] Figure 4 Schematic diagram of the magnetic tunnel junction structure in an embodiment of the present invention Figure 2 .

[0049] Figure 5Schematic diagram of the structure of the storage unit in the embodiment of the present invention Figure 1 .

[0050] Figure 6 Schematic diagram of the structure of the storage unit in the embodiment of the present invention Figure 2 . DETAILED DESCRIPTION

[0051] It should be noted that the terms “surface” and “on” in this specification are used to describe relative positional relationships in space and are not limited to direct contact.

[0052] From the background technology, it can be known that the existing storage units have the problems of low integration and low storage efficiency. Now, the reasons are analyzed in combination with the existing storage units:

[0053] Figure 1 It is a structural schematic diagram of a magnetic tunnel junction structure.

[0054] Please refer to Figure 1 The magnetic tunnel junction structure includes: a conductive layer 104; a magnetic tunnel junction unit 100 located on the surface of the conductive layer 104, and the magnetic tunnel junction unit 100 includes a free layer 103 located on the surface of the conductive layer 104, a barrier layer 102 located on the surface of the free layer 103, and a reference layer 101 located on the surface of the barrier layer 102.

[0055] Figure 2 It is a structural diagram of a storage unit.

[0056] Please Figure 1 Based on reference Figure 2 The storage unit includes: a conductive layer 104, wherein the conductive layer 104 includes a first end and a second end; a magnetic tunnel junction unit 100, wherein the magnetic tunnel junction unit 100 includes: a free layer 103 electrode and a reference layer 101 electrode, wherein the free layer 103 electrode of the magnetic tunnel junction unit 100 is electrically connected to the conductive layer 104; a first MOS transistor M1, wherein one of the source or drain of the first MOS transistor M1 is connected to the first end of the conductive layer 104; a second MOS transistor M2, wherein one of the source or drain of the second MOS transistor M2 is connected to to the first end of the conductive layer 104; a source line SL, the source line SL is connected to the second end of the conductive layer 104; a write word line WWL, the write word line WWL is connected to the gate of the first MOS transistor M1; a write bit line WBL, the write bit line WBL is connected to one of the source or the drain of the first MOS transistor M1; a read word line RWL, the read word line RWL is connected to the gate of the second MOS transistor M2; a read bit line RBL, the read bit line RBL is connected to one of the source or the drain of the second MOS transistor M2.

[0057] In the above scheme, the first MOS transistor M1 is used for writing operation, and the second MOS transistor M2 is used for reading operation, and the two MOS transistors can only write or read one magnetic tunnel junction unit 100. On the one hand, the use of two MOS transistors increases the area of ​​the storage unit, which is not conducive to the integration of the memory. On the other hand, only one magnetic tunnel junction structure can be written or read at a time, which reduces the storage efficiency of the storage unit. If multiple magnetic tunnel junction structures are to be stored, the above storage units need to be arranged in the form of an array to form a storage array (not shown in the figure). Since each storage unit has two MOS transistors, the number of MOS transistors in the storage array increases by a multiple of 2, further increasing the area of ​​the memory.

[0058] In order to solve the problems of large storage unit area and reduced storage efficiency, the present invention also provides a magnetic tunnel junction structure, wherein the N magnetic tunnel junction units are located on the same conductive layer, thereby increasing the density of the magnetic tunnel junction units, reducing the area of ​​circuit design, and improving circuit integration. The N magnetic tunnel junction units are simultaneously connected to a conductive layer, so that one MOS tube can provide write current for the N magnetic tunnel junction units at the same time, thereby achieving improved storage efficiency.

[0059] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0060] Figure 3 Schematic diagram of the magnetic tunnel junction structure in an embodiment of the present invention Figure 1 .

[0061] Figure 4 Schematic diagram of the magnetic tunnel junction structure in an embodiment of the present invention Figure 2 .

[0062] Please refer to Figure 3 as well as Figure 4 , Figure 4 This is a top view of the structure. Figure 3 yes Figure 4 In the cross-sectional schematic diagram along line AA1, the magnetic tunnel junction structure includes: a conductive layer 204; at least two magnetic tunnel junction units 200 located on the surface of the conductive layer 204, the at least two magnetic tunnel junction units 200 are arranged along a first direction X, each of the magnetic tunnel junction units 200 includes a free layer 203 located on the surface of the conductive layer 204, a barrier layer 202 located on the surface of the free layer 203, and a reference layer 201 located on the surface of the barrier layer 202, and the operating currents of different magnetic tunnel junction units 200 are different.

[0063] In this embodiment, the material of the free layer 203 includes cobalt iron boron, and the material of the reference layer 201 includes magnesium oxide. Of course, the present invention does not limit the materials of the reference layer 201 and the free layer 203, and other materials or combinations of materials are within the protection scope of the present invention.

[0064] The working process of the magnetic tunnel junction unit 200 of this embodiment is described below:

[0065] When current flows from the reference layer 201 to the free layer 203 , the magnetization directions of the reference layer 201 and the free layer 203 are parallel, and the magnetic tunnel junction unit 200 is in a low resistance state. At this time, the storage data in the magnetic tunnel junction unit 200 is logic 1.

[0066] When current flows from the free layer 203 to the reference layer 201 , the magnetization directions of the reference layer 201 and the free layer 203 are antiparallel, and the magnetic tunnel junction unit 200 is in a high resistance state. At this time, the storage data in the magnetic tunnel junction unit 200 is logic 0.

[0067] Please continue to refer to Figure 4 The magnetic tunnel junction units 200 are arranged along a first direction X, and different magnetic tunnel junction units 200 have different widths W2 in a second direction Y. The second direction Y is parallel to the surface of the conductive layer 204 , and the second direction Y is perpendicular to the first direction X.

[0068] In this embodiment, the widths W2 of the at least two magnetic tunnel junction units 200 increase one by one along the first direction X, and the operating currents of the at least two magnetic tunnel junction units 200 increase one by one along the first direction X.

[0069] In this embodiment, the N magnetic tunnel junction units 200 include a first magnetic tunnel junction unit MTJ1 to an Nth magnetic tunnel junction unit MTJN arranged from the first end to the second end.

[0070] In this embodiment, the conductive layer 204 includes a plurality of device regions 208 , each magnetic tunnel junction unit 200 is located on a surface of a device region 208 , and there is a preset size difference between a width W1 of the device region 208 in the second direction Y and a width W2 of the magnetic tunnel junction unit 200 .

[0071] In this embodiment, the material of the conductive layer 204 is one or a combination of platinum, tantalum and tungsten.

[0072] In this embodiment, the width W1 of the conductive layer 204 connected to the first magnetic tunnel junction unit MTJ1 in the second direction Y is 75nm, and the switching current required for the first magnetic tunnel junction unit MTJ1 is 110μA; the width W1 of the conductive layer 204 connected to the second magnetic tunnel junction unit MTJ2 in the second direction Y is 95nm, and the switching current required for the second magnetic tunnel junction unit MTJ2 is 140μA; the width W1 of the conductive layer 204 connected to the third magnetic tunnel junction unit MTJ3 in the second direction Y is 115nm, and the switching current required for the third magnetic tunnel junction unit MTJ3 is 175μA.

[0073] In other embodiments not shown in the figures, the width of the conductive layer connected to the fourth magnetic tunnel junction unit in the second direction is 135nm, and the switching current required for the fourth magnetic tunnel junction unit is 140μA; the width of the conductive layer connected to the fifth magnetic tunnel junction unit in the second direction is 205nm, and the switching current required for the fifth magnetic tunnel junction unit is 255μA.

[0074] The switching current is the operating current in this embodiment.

[0075] It can be seen that the operating current is proportional to the width W1 of the conductive layer 204 in the second direction Y.

[0076] In addition, in a specific embodiment, when a specified current is applied to the conductive layer 204, and the current density on the conductive layer 204 exceeds 7.5 x 10 7 A / cm 2 When , the magnetic tunnel junction unit 200 switches.

[0077] Specifically, the specified current is 120 μA, 150 μA, 180 μA and 225 μA.

[0078] Correspondingly, the present invention also provides a method for forming the magnetic tunnel junction structure.

[0079] Correspondingly, the present invention also provides a storage unit.

[0080] Figure 5 Schematic diagram of the structure of the storage unit in the embodiment of the present invention Figure 1 .

[0081] Please refer to Figure 5, the storage unit includes: a conductive layer 204, the conductive layer 204 includes a first end and a second end; N magnetic tunnel junction units 200, each of the magnetic tunnel junction units 200 includes: a free layer 203 electrode and a reference layer 201 electrode, the free layer 203 electrodes of the N magnetic tunnel junction units 200 are electrically connected to the conductive layer 204, and the operating currents of the N magnetic tunnel junction units 200 are different, wherein N>1, and N is a positive integer; a first source line SL1; a MOS tube 205, one of the source or drain of the MOS tube 205 is connected to the first end of the conductive layer 204, and the other source or drain of the MOS tube 205 is connected to the first source line SL1; a second source line SL2, the second source line SL2 is connected to the second end of the conductive layer 204.

[0082] In this embodiment, the MOS transistor 205 includes an NMOS transistor or a PMOS transistor.

[0083] In this embodiment, when the MOS transistor 205 includes a PMOS transistor, the source of the PMOS transistor is connected to the first source line SL1 , and the drain of the PMOS transistor is connected to the first end of the conductive layer 204 .

[0084] In this embodiment, when the MOS transistor 205 includes an NMOS transistor, the drain of the NMOS transistor is connected to the first source line SL1 , and the source of the NMOS transistor is connected to the first end of the conductive layer 204 .

[0085] Please continue to refer to Figure 5 The storage unit further includes: a word line WL, to which the gate of the MOS tube 205 is connected; N bit lines BL1 to BLN, to which the reference layer 201 electrodes of the N magnetic tunnel junction units 200 are connected one by one.

[0086] In this embodiment, the word line WL is used to control the on or off state of the MOS tube 205. Specifically, when the storage unit is in the writing process, a first level is applied to the gate of the MOS tube 205, so that the MOS tube 205 is in the on state; when the storage unit is in the reading process, a second level is applied to the gate of the MOS tube 205, so that the MOS tube 205 is in the off state.

[0087] In this embodiment, the MOS transistor 205 is an NMOS transistor, the first level is a high level, and the second level is a low level.

[0088] Figure 6 Schematic diagram of the structure of the storage unit in the embodiment of the present invention Figure 2 .

[0089] Please refer to Figure 6 The N magnetic tunnel junction units 200 are arranged along a first direction X, and the widths W2 of the N magnetic tunnel junction units 200 in a second direction Y are different. The second direction Y is parallel to the surface of the conductive layer 204, and the second direction Y is perpendicular to the first direction X.

[0090] In this embodiment, the width W2 of the magnetic tunnel junction unit 200 increases along the first direction X, and the operating currents corresponding to the N magnetic tunnel junction units 200 increase along the first direction X.

[0091] In this embodiment, the N magnetic tunnel junction units 200 increase in geometric proportion along the first direction X, and the operating currents corresponding to the N magnetic tunnel junction units 200 increase in geometric proportion along the first direction X.

[0092] Please continue to refer to Figure 6 The conductive layer 204 includes a plurality of device regions 208 , each magnetic tunnel junction unit 200 is located on a surface of a device region 208 , and there is a preset size difference between a width W1 of the device region 208 in the second direction Y and a width W2 of the magnetic tunnel junction unit 200 .

[0093] In this embodiment, the storage unit further includes N diodes 206 , the anodes of the N diodes 206 are connected to the reference layer 201 electrodes of the N magnetic tunnel junction units 200 in a one-to-one correspondence, and the cathodes of the N diodes 206 are all connected to the word line WL.

[0094] In this embodiment, the storage unit also includes: a write operation unit 207, and the write operation unit 207 is used to: put the MOS tube 205 in a conductive state; apply a first level to the first end of the conductive layer 204, and apply a second level to the second end of the conductive layer 204, the first level is opposite to the second level, and the conductive layer 204 generates a write current Iwrite to write data to N magnetic tunnel junction units 200.

[0095] Specifically, the writing of data to the N magnetic tunnel junction units 200 includes: when the current value of the write current Iwrite is between the operating current Ii of the i-th magnetic tunnel junction unit MTJi and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit MTJi+1, the first magnetic tunnel junction unit MTJ1 to the i-th magnetic tunnel junction unit MTJi are in a first resistance state, and the i+1-th magnetic tunnel junction unit MTJi+1 to the N-th magnetic tunnel junction unit MTJN are in a second resistance state, wherein 1≤i≤N-1, i is a positive integer, and the first resistance state is opposite to the second resistance state.

[0096] The first resistance state is a high resistance state, and the second resistance state is a low resistance state.

[0097] In this embodiment, the storage unit also includes: a read operation unit 207, and the read operation unit 207 is used to: put the MOS tube 205 in a cut-off state, apply a first level to the second end of the conductive layer 204; obtain a read current Iread flowing through the reference layer 201 electrode of the N magnetic tunnel junction units 200, and read the written data in the N magnetic tunnel junction units 200.

[0098] Specifically, the reading of the write data in the N magnetic tunnel junction units 200 includes: when the current value of the read current Iread is between the operating current Ii of the i-th magnetic tunnel junction unit MTJi and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit MTJi+1, according to the first resistance state of the first magnetic tunnel junction unit MTJ1 to the i-th magnetic tunnel junction unit MTJi and the second resistance state of the i+1-th magnetic tunnel junction unit MTJi+1 to the N-th magnetic tunnel junction unit MTJN, reading the write data in the N magnetic tunnel junction units 200, wherein 1≤i≤N-1, i is a positive integer, and the write data represented by the first resistance state and the second resistance state are opposite.

[0099] In this embodiment, Figure 5 The storage states of each magnetic tunnel junction unit 200 are shown in Table 1:

[0100]

[0101] Table 1

[0102] The following example takes the high level voltage value of 1.8V and the low level voltage value of 0V as an example. Figure 5 The working process of the storage unit of this embodiment is described as follows:

[0103] It should be noted that the MOS transistor 205 in this embodiment is an NMOS transistor.

[0104] During the writing process, a high level is applied to the gate of the MOS tube 205 connected to the word line WL, so that the MOS tube 205 is in a conductive state, a high level is applied to the drain of the MOS tube 205 connected to the first source line SL1, and a low level is applied to the second source line SL2 connected to the second end of the conductive layer 204, so that the write current Iwrite flows from the first end to the second end of the conductive layer 204.

[0105] In one embodiment, when the write current Iwrite is greater than the operating current of the first magnetic tunnel junction unit MTJ1 during the period from the operating current of the first magnetic tunnel junction unit MTJ1 to the operating current of the second magnetic tunnel junction unit MTJ2, at this time, the first magnetic tunnel junction unit MTJ1 is in a high resistance state, that is, logic 0 is written, and the second magnetic tunnel junction unit MTJ2 to the Nth magnetic tunnel junction unit MTJN are in a low resistance state, that is, logic 1 is written.

[0106] In another embodiment, when the write current Iwrite is greater than the operating current of the second magnetic tunnel junction unit MTJ2 during the period from the operating current of the second magnetic tunnel junction unit MTJ2 to the operating current of the third magnetic tunnel junction unit MTJ3, at this time, the first magnetic tunnel junction unit MTJ1 and the second magnetic tunnel junction unit MTJ2 are in a high resistance state, that is, logic 0 is written, and the third magnetic tunnel junction unit MTJ3 to the Nth magnetic tunnel junction unit MTJN are in a low resistance state, that is, logic 1 is written.

[0107] In another embodiment, when the write current Iwrite is greater than the operating current of the i-th magnetic tunnel junction unit MTJi during the operation current of the i+1-th magnetic tunnel junction unit MTJi+1, at this time, the first magnetic tunnel junction unit MTJ1 to the i-th magnetic tunnel junction unit MTJi are in a high resistance state, that is, logic 0 is written, and the i+1-th magnetic tunnel junction unit MTJi+1 to the N-th magnetic tunnel junction unit MTJN are in a low resistance state, that is, logic 1 is written.

[0108] In other embodiments, a low level is applied to the drain of the MOS tube 205 connected to the first source line SL1, and a high level is applied to the second source line SL2 connected to the second end of the conductive layer 204, so that the write current Iwrite flows from the second end to the first end of the conductive layer 204, so that the written data is reversed, wherein the writing process is the same as the above-mentioned scheme and will not be repeated here.

[0109] During the reading process, a low level is applied to the gate of the MOS tube 205 connected to the word line WL, so that the MOS tube 205 is in a cut-off state, and a high level is applied to the second source line SL2 connected to the second end of the conductive layer 204 to obtain the read current Iread flowing through the reference layer 201 electrode of the N magnetic tunnel junction units 200.

[0110] In one embodiment, when the read current Iread is greater than the operating current of the first magnetic tunnel junction unit MTJ1 during the period from the operating current of the first magnetic tunnel junction unit MTJ1 to the operating current of the second magnetic tunnel junction unit MTJ2, at this time, the first magnetic tunnel junction unit MTJ1 is in a high resistance state, i.e., the reading logic 0, and the second magnetic tunnel junction unit MTJ2 to the Nth magnetic tunnel junction unit MTJN are in a low resistance state, i.e., the reading logic 1.

[0111] In another embodiment, when the read current Iread is greater than the operating current of the second magnetic tunnel junction unit MTJ2 during the period from the operating current of the second magnetic tunnel junction unit MTJ2 to the operating current of the third magnetic tunnel junction unit MTJ3, at this time, the first magnetic tunnel junction unit MTJ1 and the second magnetic tunnel junction unit MTJ2 are in a high resistance state, i.e., reading logic 0, and the third magnetic tunnel junction unit MTJ3 to the Nth magnetic tunnel junction unit MTJN are in a low resistance state, i.e., reading logic 1.

[0112] In another embodiment, when the read current Iread is greater than the operating current of the i-th magnetic tunnel junction unit MTJi when the operating current of the i-th magnetic tunnel junction unit 200 is to the operating current of the i+1-th magnetic tunnel junction unit MTJi+1, at this time, the first magnetic tunnel junction unit MTJ1 to the i-th magnetic tunnel junction unit MTJi are in a high resistance state, that is, the reading logic 0, and the i+1-th magnetic tunnel junction unit MTJi+1 to the N-th magnetic tunnel junction unit MTJN are in a low resistance state, that is, the reading logic 1.

[0113] Correspondingly, the technical solution of the present invention also provides a memory, including the above-mentioned storage unit.

[0114] Please continue to refer to Figure 5 as well as Figure 6 The technical solution of the present invention also provides a method for writing a storage unit, comprising: making the MOS tube 205 in a conducting state; applying a first level to a first end of a conductive layer 204, applying a second level to a second end of the conductive layer 204, wherein the first level is opposite to the second level, and the conductive layer 204 generates a write current Iwrite, and writes data to N magnetic tunnel junction units 200, wherein N>1, and N is a positive integer.

[0115] In this embodiment, the N magnetic tunnel junction units 200 include a first magnetic tunnel junction unit MTJ1 to an Nth magnetic tunnel junction unit MTJN arranged from the first end to the second end.

[0116] In this embodiment, the writing of data to the N magnetic tunnel junction units 200 includes: when the current value of the write current Iwrite is between the operating current Ii of the i-th magnetic tunnel junction unit MTJi and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit MTJi+1, the first magnetic tunnel junction unit MTJ1 to the i-th magnetic tunnel junction unit MTJi are in a first resistance state, and the i+1-th magnetic tunnel junction unit MTJi+1 to the N-th magnetic tunnel junction unit MTJN are in a second resistance state, wherein 1≤i≤N-1, i is a positive integer, and the first resistance state is opposite to the second resistance state.

[0117] Correspondingly, the technical solution of the present invention also provides a method for reading a storage unit, including: putting the MOS tube 205 in a cut-off state, applying a first level to the second end of the conductive layer 204; obtaining a read current Iread flowing through the reference layer electrode of the N magnetic tunnel junction units 200, and reading the written data in the N magnetic tunnel junction units 200, wherein N>1, and N is a positive integer.

[0118] In this embodiment, the N magnetic tunnel junction units 200 include a first magnetic tunnel junction unit MTJ1 to an Nth magnetic tunnel junction unit MTJN arranged from the first end to the second end.

[0119] In this embodiment, when the current value of the read current Iread is between the operating current Ii of the i-th magnetic tunnel junction unit MTJi and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit MTJi+1, the write data in the N magnetic tunnel junction units 200 are read according to the first resistance state of the first magnetic tunnel junction unit MTJ1 to the i-th magnetic tunnel junction unit MTJi and the second resistance state of the i+1-th magnetic tunnel junction unit MTJi+1 to the N-th magnetic tunnel junction unit MTJN, wherein 1≤i≤N-1, i is a positive integer, and the write data represented by the first resistance state and the second resistance state are opposite.

[0120] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A magnetic tunnel junction structure, characterized in that: include: Conductive layer; At least two magnetic tunnel junction units are located on the surface of the conductive layer, and the at least two magnetic tunnel junction units are arranged along a first direction. Each of the magnetic tunnel junction units includes a free layer located on the surface of the conductive layer, a barrier layer located on the surface of the free layer, and a reference layer located on the surface of the barrier layer. The operating currents of different magnetic tunnel junction units are different.

2. The magnetic tunnel junction structure according to claim 1, wherein: The magnetic tunnel junction units are arranged along a first direction, and different magnetic tunnel junction units have different widths in a second direction. The second direction is parallel to the surface of the conductive layer, and the second direction is perpendicular to the first direction.

3. The magnetic tunnel junction structure according to claim 2, characterized in that: The widths of the at least two magnetic tunnel junction units increase one by one along a first direction, and the operating currents of the at least two magnetic tunnel junction units increase one by one along the first direction.

4. The magnetic tunnel junction structure according to claim 2, characterized in that: The conductive layer includes a plurality of device regions, each magnetic tunnel junction unit is located on a surface of a device region, and there is a preset size difference between the width of the device region in the second direction and the width of the magnetic tunnel junction unit.

5. The magnetic tunnel junction structure according to claim 2, characterized in that: The material of the conductive layer is one or more of platinum, tantalum and tungsten.

6. A method for forming a magnetic tunnel junction structure according to any one of claims 1 to 5.

7. A storage unit, characterized in that: include: A conductive layer, the conductive layer comprising a first end and a second end; N magnetic tunnel junction units, each of which includes: a free layer electrode and a reference layer electrode, the free layer electrodes of the N magnetic tunnel junction units are electrically connected to the conductive layer, and the operating currents of the N magnetic tunnel junction units are different, wherein N>1, and N is a positive integer; a first source line; A MOS tube, wherein one of a source or a drain of the MOS tube is connected to the first end of the conductive layer, and the other source or drain of the MOS tube is connected to the first source line; A second source line is connected to a second end of the conductive layer.

8. The storage unit according to claim 7, characterized in that Also includes: A word line, to which the gate of the MOS tube is connected; N bit lines, and the reference layer electrodes of the N magnetic tunnel junction units are connected to the N bit lines in a one-to-one correspondence.

9. The storage unit according to claim 8, characterized in that The N magnetic tunnel junction units are arranged along a first direction, and the widths of the N magnetic tunnel junction units in a second direction are different. The second direction is parallel to the surface of the conductive layer, and the second direction is perpendicular to the first direction.

10. The storage unit according to claim 9, characterized in that The width of the magnetic tunnel junction unit increases along a first direction, and the operating currents corresponding to the N magnetic tunnel junction units increase along the first direction.

11. The storage unit according to claim 10, characterized in that The N magnetic tunnel junction units increase in geometric proportion along a first direction, and the operating currents corresponding to the N magnetic tunnel junction units increase in geometric proportion along the first direction.

12. The storage unit according to claim 11, characterized in that The conductive layer includes a plurality of device regions, each magnetic tunnel junction unit is located on a surface of a device region, and there is a preset size difference between the width of the device region in the second direction and the width of the magnetic tunnel junction unit.

13. The storage unit according to claim 7, wherein: The MOS tube includes an NMOS tube or a PMOS tube.

14. The storage unit according to claim 13, characterized in that When the MOS tube includes a PMOS tube, a source of the PMOS tube is connected to the first source line, and a drain of the PMOS tube is connected to the first end of the conductive layer.

15. The storage unit according to claim 13, characterized in that When the MOS tube includes an NMOS tube, the drain of the NMOS tube is connected to the first source line, and the source of the NMOS tube is connected to the first end of the conductive layer.

16. The storage unit according to claim 8, characterized in that It also includes N diodes, wherein the anodes of the N diodes are connected to the reference layer electrodes of the N magnetic tunnel junction units one by one, and the cathodes of the N diodes are all connected to the word lines.

17. The storage unit according to claim 7, characterized in that The N magnetic tunnel junction units include a first magnetic tunnel junction unit to an Nth magnetic tunnel junction unit arranged from the first end to the second end.

18. The storage unit according to claim 17, characterized in that Also includes: A write operation unit, the write operation unit is used to: put the MOS tube into a conducting state; A first level is applied to a first end of the conductive layer, and a second level is applied to a second end of the conductive layer, wherein the first level is opposite to the second level, and the conductive layer generates a write current Iwrite to write data to N magnetic tunnel junction units.

19. The storage unit according to claim 18, characterized in that The writing of data to the N magnetic tunnel junction units includes: when the current value of the write current Iwrite is between the operating current Ii of the i-th magnetic tunnel junction unit and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit, the first magnetic tunnel junction unit to the i-th magnetic tunnel junction unit are in a first resistance state, and the i+1-th magnetic tunnel junction unit to the N-th magnetic tunnel junction unit are in a second resistance state, wherein 1≤i≤N-1, i is a positive integer, and the first resistance state is opposite to the second resistance state.

20. The storage unit according to claim 17, wherein: Also includes: A read operation unit, the read operation unit is used to: put the MOS tube in a cut-off state, and apply a first level to the second end of the conductive layer; A read current Iread flowing through the reference layer electrodes of the N magnetic tunnel junction units is obtained to read the written data in the N magnetic tunnel junction units.

21. The storage unit according to claim 20, characterized in that The reading of the write data in the N magnetic tunnel junction units includes: when the current value of the read current Iread is between the operating current Ii of the i-th magnetic tunnel junction unit and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit, according to the first resistance state of the first magnetic tunnel junction unit to the i-th magnetic tunnel junction unit and the second resistance state of the i+1-th magnetic tunnel junction unit to the N-th magnetic tunnel junction unit, reading the write data in the N magnetic tunnel junction units, wherein 1≤i≤N-1, i is a positive integer, and the write data represented by the first resistance state and the second resistance state are opposite.

22. A memory, characterized in that: A storage unit comprising any one of claims 7 to 21.

23. A method for writing into a storage unit according to any one of claims 7 to 21, characterized in that: include: Make the MOS tube in the on state; A first level is applied to a first end of a conductive layer, and a second level is applied to a second end of the conductive layer, wherein the first level is opposite to the second level, and the conductive layer generates a write current Iwrite to write data to N magnetic tunnel junction units, wherein N>1 and N is a positive integer.

24. The method for writing into a storage unit as claimed in claim 23, characterized in that: The N magnetic tunnel junction units include a first magnetic tunnel junction unit to an Nth magnetic tunnel junction unit arranged from the first end to the second end.

25. The method for writing into a storage unit as claimed in claim 24, characterized in that: The writing of data to the N magnetic tunnel junction units includes: when the current value of the write current Iwrite is between the operating current Ii of the i-th magnetic tunnel junction unit and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit, the first magnetic tunnel junction unit to the i-th magnetic tunnel junction unit are in a first resistance state, and the i+1-th magnetic tunnel junction unit to the N-th magnetic tunnel junction unit are in a second resistance state, wherein 1≤i≤N-1, i is a positive integer, and the first resistance state is opposite to the second resistance state.

26. A method for reading a storage unit according to any one of claims 7 to 21, characterized in that: include: The MOS tube is in a cut-off state, and a first level is applied to the second end of the conductive layer; A read current Iread flowing through the reference layer electrodes of the N magnetic tunnel junction units is obtained, and written data in the N magnetic tunnel junction units is read, wherein N>1 and N is a positive integer.

27. The method for reading a storage unit according to claim 26, wherein: The N magnetic tunnel junction units include a first magnetic tunnel junction unit to an Nth magnetic tunnel junction unit arranged from the first end to the second end.

28. The method for reading a storage unit according to claim 27, characterized in that: When the current value of the read current Iread is between the operating current Ii of the i-th magnetic tunnel junction unit and the operating current Ii+1 of the i+1-th magnetic tunnel junction unit, the write data in the N magnetic tunnel junction units are read according to the first resistance state of the first magnetic tunnel junction unit to the i-th magnetic tunnel junction unit and the second resistance state of the i+1-th magnetic tunnel junction unit to the N-th magnetic tunnel junction unit, wherein 1≤i≤N-1, i is a positive integer, and the write data represented by the first resistance state and the second resistance state are opposite.

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