MEMORY AND ELECTRONIC DEVICE

An example memory includes a plurality of storage units and bit lines distributed in an array in a storage area of the memory, where each of the storage unit includes a transistor and a magnetic tunnel junction (MTJ) element connected to the transistor. The MTJ element is disposed on a current transmission path between a source or a drain of the transistor and the bit line. The MTJ element includes a pinning layer, a reference layer, a tunneling layer, and a free layer that are stacked in sequence, and a magnetization direction of the pinning layer is parallel to a stacking direction of layers in the MTJ. The example memory further includes a first magnetic structure disposed on the current transmission path and in contact with the MTJ element. An included angle between a magnetization direction of the first magnetic structure and the magnetization direction of the pinning layer is (90°, 180°].

TECHNICAL FIELD

This application relates to the field of memory technologies, and in particular, to a memory and an electronic device.

BACKGROUND

A magnetic random access memory (MRAM) is a new-type non-volatile memory. A spin transfer torque magnetic random access memory (STT MRAM) has gained wide attention because of its advantages such as a high speed, low power consumption, and good COMS (complementary metal-oxide-semiconductor) compatibility.

Reading and writing functions of the spin transfer torque magnetic random access memory are implemented by a storage unit of the spin transfer torque magnetic random access memory. A main structure of the storage unit includes a magnetic tunnel junction (MTJ) element and a transistor. A structure of the MTJ mainly includes a free layer for storing information, a tunneling layer, a reference layer with a fixed magnetization direction, and a pinning layer that are stacked in sequence. The magnetization direction of the reference layer is pinned by the pinning layer in a specific direction, and a magnetization direction of the free layer may change. When currents flow through the MTJ in different directions (where the current flows from a fixed layer to the free layer or the current flows from the free layer to the fixed layer), the magnetization direction of the free layer changes accordingly. When the magnetization direction of the free layer is parallel to the magnetization direction of the reference layer, in other words, when the magnetization direction of the free layer is the same as the magnetization direction of the reference layer, the storage unit presents low resistance, and stored information is “0”. When the magnetization direction of the free layer is oppositely parallel to the magnetization direction of the reference layer, in other words, when the magnetization direction of the free layer is opposite to the magnetization direction of the reference layer, the storage unit presents high resistance, and stored information is “1”. Reading of the magnetic random access memory is to detect resistance of a storage unit. A constant small current flows through an MTJ from a bit line, and a potential difference is generated at two ends of the MTJ. Resistance of the MTJ may be determined based on a value of the potential difference, and then it may be determined that information stored in the magnetic random access memory is “0” or “1”.

Currently, because the pinning layer has a strong stray field, the free layer generates a large compensation field. In this way, a current required for flipping the free layer is increased.

SUMMARY

Embodiments of this application provide a memory and an electronic device, to resolve a problem of a large current required for flipping a free layer in an MTJ.

According to a first aspect, a memory is provided. The memory includes a plurality of storage units and bit lines distributed in an array in a storage area of the memory, where the storage unit includes a transistor and a magnetic tunnel junction MTJ element connected to the transistor. The MTJ element is disposed on a current transmission path between a source or a drain of the transistor and the bit line, the MTJ element includes a pinning layer, a reference layer, a tunneling layer, and a free layer that are stacked in sequence, and a magnetization direction of the pinning layer is parallel to a stacking direction of layers in the MTJ. The memory further includes a first magnetic structure disposed on the current transmission path and in contact with the MTJ element. An included angle between a magnetization direction of the first magnetic structure and the magnetization direction of the pinning layer is (90°, 180° ]. Because the included angle between the magnetization direction of the first magnetic structure and the magnetization direction of the pinning layer is (90°, 180° ], a magnetic field generated by the first magnetic structure at the free layer can cancel a magnetic field generated by the pinning layer at the free layer, so that a compensation field generated by the free layer can be reduced or eliminated. In this way, a current required for flipping the free layer is reduced, and a problem of flipping asymmetry in the MTJ can be resolved. In addition, because the magnetic field generated by the pinning layer at the free layer may be canceled by the magnetic field generated by the first magnetic structure at the free layer, a difference caused by impact of a stray field on the free layer does not need to be overcome by increasing a current. In this way, a magnetization direction of the free layer can be flipped by using a small current, so that power can be reduced, durability of the MTJ can be improved, and a lifespan of the MTJ can be improved.

In a possible implementation, the magnetization direction of the first magnetic structure is opposite to the magnetization direction of the pinning layer, and a magnitude of the magnetic field generated by the first magnetic structure at the free layer is the same as that of the magnetic field generated by the pinning layer at the free layer. In this way, the magnetic field generated by the first magnetic structure at the free layer can cancel the magnetic field generated by the pinning layer at the free layer. Therefore, a magnetic field, generated by another layer, applied to the free layer is zero or approaches zero, and a compensation field generated by the free layer due to the magnetic field generated by the another layer is zero or approaches zero. This further reduces the current required for flipping the free layer, and more effectively resolves the problem of flipping asymmetry in the MTJ.

In a possible implementation, the magnetization direction of the first magnetic structure is opposite to the magnetization direction of the pinning layer, and a magnitude of the magnetic field generated by the first magnetic structure at the free layer is the same as magnitudes of magnetic fields generated by the pinning layer and the reference layer at the free layer. In this way, both the magnetic fields generated by the pinning layer and the reference layer at the free layer can be canceled by the magnetic field generated by the first magnetic structure at the free layer. This further reduces the current required for flipping the free layer.

In a possible implementation, the first magnetic structure is connected between the MTJ element and the source or the drain of the transistor.

In a possible implementation, the first magnetic structure is connected between the MTJ element and the bit line.

In a possible implementation, the MTJ element further includes a first electrode and a second electrode; the first electrode is located on a side that is of the free layer and that is away from the pinning layer, and the second electrode is located on a side that is of the pinning layer and that is away from the free layer; and the first electrode is electrically connected to the bit line, and the second electrode is electrically connected to the source or the drain of the transistor; or the first electrode is electrically connected to the source or the drain of the transistor, and the second electrode is electrically connected to the bit line. Herein, magnitudes of voltages applied to the first electrode and the second electrode determine a flow direction of a current in the MTJ element.

In a possible implementation, a material of the first magnetic structure includes one or more of monatomic cobalt, monatomic iron, monatomic nickel, and an alloy including at least one of cobalt, iron, or nickel.

In a possible implementation, the pinning layer includes a ferromagnetic layer and a heavy metal layer that are alternately stacked along the stacking direction of the layers in the MTJ. Compared with a current technology in which the pinning layer includes a first pinning sub-layer, a non-magnetic layer, and a second pinning sub-layer, and the first pinning sub-layer and the second pinning sub-layer each include a ferromagnetic layer and a heavy metal layer that are alternately stacked along the stacking direction of the layers in the MTJ, in this embodiment of this application, because the pinning layer in this embodiment of this application includes only the ferromagnetic layer and the heavy metal layer that are alternately stacked along the stacking direction of the layers in the MTJ, a thickness of the pinning layer is greatly reduced, and a structure is simplified. This helps reduce roughness of an interface between the tunneling layer and the free layer, reduce stress accumulation, and facilitate miniaturization of the MTJ. In addition, because the thickness of the pinning layer is greatly reduced, in other words, thickness of a conductive material below the tunneling layer is reduced, a probability of a short circuit caused by resputtering in an etching process is reduced, and an engineering yield is improved.

In a possible implementation, a material of the ferromagnetic layer includes one or more of monatomic cobalt, monatomic iron, monatomic nickel, and an alloy including at least one of cobalt, iron, or nickel; and a material of the heavy metal layer includes one or more of monatomic platinum, monatomic tantalum, monatomic copper, monatomic iridium, monatomic ruthenium, monatomic tungsten, and an alloy including at least one of platinum, tantalum, copper, iridium, ruthenium, or tungsten.

In a possible implementation, a material of the pinning layer is a perpendicular magnetic anisotropy material. Because the material of the pinning layer is the perpendicular magnetic anisotropy material, the magnetization direction of the pinning layer is easily magnetized to be parallel to the stacking direction of the layers in the MTJ. In this way, thickness of the pinning layer may be set to be small. Therefore, compared with a current technology, in this embodiment of this application, the thickness of the pinning layer is greatly reduced, and a structure is simplified. This helps reduce roughness of an interface between the tunneling layer and the free layer, reduce stress accumulation, and facilitate miniaturization of the MTJ. In addition, because the thickness of the pinning layer is greatly reduced, in other words, thickness of a conductive material below the tunneling layer is reduced, a probability of a short circuit caused by resputtering in an etching process is reduced, and an engineering yield is improved.

In a possible implementation, the material of the pinning layer includes one or more of an iron-platinum alloy and a cobalt-platinum alloy.

In a possible implementation, materials of the reference layer and the free layer include a cobalt-ferroboron CoFeB alloy; and a material of the tunneling layer includes magnesium oxide MgO.

In a possible implementation, a gate of the transistor is connected to a word line control circuit through a word line WL, the source or the drain of the transistor is connected to a data line, and the bit line BL is connected to a bit line control circuit.

In a possible implementation, the memory further includes a second magnetic structure disposed on the current transmission path; a direction of a magnetic field generated by the second magnetic structure at the free layer is not parallel to a magnetization direction of the free layer; and a projection of the MTJ element on a connection layer does not overlap a projection of the second magnetic structure on the connection layer. The first magnetic structure is connected between the MTJ element and the source or the drain of the transistor, and the second magnetic structure is connected between the MTJ element and the bit line; or the first magnetic structure is connected between the MTJ element and the bit line, and the second magnetic structure is connected between the MTJ element and the source or the drain of the transistor. Because the direction of the magnetic field generated by the second magnetic structure at the free layer is not parallel to the magnetization direction of the free layer, the magnetic field generated by the second magnetic structure at the free layer may apply magnetic field force to the free layer. This facilitates flipping of the free layer. In this way, the current required for flipping the free layer is reduced, STT incubation time is reduced, and a flipping speed of the free layer is increased.

In a possible implementation, the direction of the magnetic field generated by the second magnetic structure at the free layer is perpendicular to the magnetization direction of the free layer. In this way, the magnetic field generated by the second magnetic structure at the free layer is larger, which is more conducive to flipping of the free layer. Therefore, the current required for flipping the free layer can be further reduced, the STT incubation time can be further reduced, and the flipping speed of the free layer can be more effectively improved.

In a possible implementation, the memory further includes the connection layer disposed between the second magnetic structure and the MTJ element, and the second magnetic structure is electrically connected to the MTJ element through the connection layer; and the projection of the MTJ element on the connection layer does not overlap at least a part of areas of the projection of the second magnetic structure on the connection layer. The direction of the magnetic field generated by the second magnetic structure at the free layer may be adjusted by adjusting a magnetization direction of the second magnetic structure and relative locations of the MTJ element and the second magnetic structure in a direction perpendicular to the stacking direction of the layers in the MTJ, to enable the direction of the magnetic field generated by the second magnetic structure at the free layer to be not parallel to the magnetization direction of the free layer.

According to a second aspect, an electronic device is provided. The electronic device includes a circuit board and a memory electrically connected to the circuit board, and the memory is the foregoing memory. The electronic device has technical effects the same as those in the foregoing embodiment. Details are not described herein again

REFERENCE NUMERALS

DESCRIPTION OF EMBODIMENTS

The following describes technical solutions in embodiments of this application with reference to the accompanying drawings in embodiments of this application. It is clear that the described embodiments are merely some rather than all of embodiments of this application.

Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by a person of ordinary skill in the art.

The following terms “first”, “second” and the like are merely intended for ease of description, and shall not be understood as an indication or implication of relative importance or implicit indication of a quantity of indicated technical features. Therefore, a feature limited by “first”, “second” and the like may explicitly indicate or implicitly include one or more such features. In addition, the term “electrical connection” may be a direct electrical connection, or may be an indirect electrical connection through an intermediate medium.

The technical solutions provided in this application may be applied to various storage systems that use a magnetic random access memory. For example, the technical solutions provided in this application are applied to a computer. For another example, the technical solutions provided in this application are applied to a storage system including a memory or a processor and a memory. The processor may be a central processing unit (central processing unit, CPU), an artificial intelligence (artificial intelligence, AI) processor, a digital signal processor (digital signal processor), a neural network processor, or the like.

FIG.1ais a schematic structural diagram of a storage system according to an embodiment of this application. The storage system may include a storage apparatus, and the storage apparatus may be a magnetic random access memory. Optionally, the storage system may further include a CPU, a cache (cache), a controller, and the like.

In an embodiment, as shown inFIG.1a, the storage system includes a CPU, a cache, and a storage apparatus that are integrated together. In another embodiment, as shown inFIG.1B, the storage system may be used as an independent memory. The storage system includes a CPU, a cache, a controller, and a storage apparatus that are integrated together. The storage apparatus is coupled to the cache and the CPU through the controller. In still another embodiment, as shown inFIG.1c, the storage system includes a storage apparatus, and a CPU, a cache, a controller, and a dynamic random access memory (dynamic random access memory, DRAM) that are integrated together. The storage apparatus may be coupled to the DRAM as an external storage apparatus. The DRAM is coupled to the cache and the CPU through the controller. The CPUs in the various storage systems shown inFIG.1a,FIG.1B, andFIG.1cmay also be replaced with CPU cores (cores). The storage apparatuses inFIG.1a,FIG.1B, andFIG.1cmay be magnetic random access memories.

The foregoing magnetic random access memory (referred to as a memory below) includes an MTJ, and the MTJ includes a pinning layer, a reference layer, a tunneling layer, and a free layer that are stacked in sequence. Because a strong magnetic field, that is, a stray field (which may also be referred to as a static magnetic field), is generated around the pinning layer, and the free layer is located around the pinning layer (for example, above the pinning layer), the pinning layer generates a strong stray field at the free layer, and the free layer generates a large compensation field. In this way, a current required for flipping the free layer is increased. When a size of the storage unit is large, the stray field generated by the pinning layer mainly has an edge effect, and has little impact on flipping of the free layer. When the size of the storage unit is small, the stray field basically acts in a direction parallel to a stacking direction of layers in the MTJ. Therefore, the stray field acts greatly in the direction parallel to the stacking direction of the layers in the MTJ, and the flipping of the free layer is greatly affected. Based on this, because a size of a storage unit in a current memory is increasingly small, impact of a stray field is increasingly large. In addition, in a highly integrated MTJ array, this problem is becoming more serious. This is because in the highly integrated MTJ array, a free layer is small and thin, is very sensitive to an external magnetic field, and has an extremely high requirement on evenness of etching. As long as a shape of the free layer after etching is different, for example, a size or a location of the free layer is different, impact of a stray field on the free layer is also greatly different. To reduce a difference, a magnitude of a current needs to be increased, to ensure reading/writing accuracy. However, increasing the current not only increases power, but also seriously affects durability of an MTJ. Consequently, a lifespan of the MTJ may be greatly reduced.

Based on the foregoing descriptions, to reduce the current required for flipping the free layer, the following describes a structure of a memory in a specific embodiment of this application by using examples.

This application provides a memory, which may be used in the foregoing storage system. As shown inFIG.2, a structure of the memory10includes a plurality of storage units11distributed in an array in a storage area of the memory10. The storage unit11includes a transistor T and a magnetic tunnel junction MTJ element12connected to the transistor T.

The transistor T may be a thin film transistor (thin film transistor, TFT), or may be a transistor of another type such as a MOS (metal oxide semiconductor) transistor. The transistor T includes a source, a drain, an active layer, a gate insulation layer, and a gate, where both the source and the drain are in contact with the active layer, and the gate insulation layer is disposed between the gate and the active layer.

As shown inFIG.2, the structure of the memory10further includes a plurality of word lines (word lines, WLs) arranged in parallel and a plurality of bit lines (bit lines, BLs) arranged in parallel, and the word line WL and the bit line BL cross each other. For example, the word line WL and the bit line BL are perpendicular to each other. In some embodiments, the memory10further includes a plurality of data lines arranged in parallel, and the data line may be parallel to the bit line BL. The gate of the transistor T is electrically connected to the word line WL, and the source or the drain of the transistor T is electrically connected to the data line. Herein, the source of the transistor T may be electrically connected to the data line. In this case, the data line may also be referred to as a source line (source line, SL). Alternatively, the drain of the transistor T may be electrically connected to the data line.FIG.2shows an example in which the source of the transistor T is electrically connected to the source line.

In some embodiments, the word line WL is further electrically connected to a word line control circuit, and the word line control circuit is used to provide a high-level signal or a low-level signal for the word line WL, so that the transistor T is in a conducted state or a cut-off state. When the transistor T is an N-type transistor, a high-level signal controls the transistor T to be conducted, and a low-level signal controls the transistor T to be cut off. When the transistor T is a P-type transistor, a low-level signal controls the transistor T to be conducted, and a high-level signal controls the transistor T to be cut off.

In some embodiments, the bit line BL is further electrically connected to a bit line control circuit, and the bit line control circuit is used to provide a signal for the bit line BL.

In some embodiments, the data line is grounded.

The MTJ element12is disposed on a current transmission path between the source or the drain of the transistor T and the bit line BL.

As shown inFIG.3a, the MTJ element12includes a first electrode121, a second electrode122, and an MTJ located between the first electrode121and the second electrode122. The MTJ includes a pinning layer1231, a reference layer1232, a tunneling layer1233, and a free layer1234that are stacked in sequence. A magnetization direction (which may also be referred to as a magnetic moment direction) of the pinning layer1231is parallel to a stacking direction of layers in the MTJ. The first electrode121is located on a side that is of the free layer1234and that is away from the pinning layer1231, and the second electrode122is located on a side that is of the pinning layer1231and that is away from the free layer1234. The first electrode121in the MTJ element12is electrically connected to the bit line BL, and the second electrode122is electrically connected to the drain or the source of the transistor T. Alternatively, the first electrode121is electrically connected to the drain or the source of the transistor T, and the second electrode122is electrically connected to the bit line BL. An example in which the first electrode121is electrically connected to the bit line BL, the second electrode122is electrically connected to the drain of the transistor T, and the source of the transistor T is electrically connected to the source line SL is used below for description.

It should be understood that when the second electrode122or the first electrode121is electrically connected to the drain of the transistor T, the source of the transistor T is electrically connected to the data line. When the second electrode122or the first electrode121is electrically connected to the source of the transistor T, the drain of the transistor is electrically connected to the data line.

It should be noted that the stacking direction of the layers in the MTJ may be from the pinning layer1231to the free layer1234, or may be from the free layer1234to the pinning layer1231. Arrows marked in the pinning layer1231inFIG.3aandFIG.3bare magnetization directions of the pinning layer1231. For example, the stacking direction of the layers in the MTJ is a direction from the pinning layer1231to the free layer1234. In this case, the arrows marked in the pinning layer1231inFIG.3aandFIG.3bmay also represent the stacking direction of the layers in the MTJ. For example, the stacking direction of the layers in the MTJ is a direction from the pinning layer1231to the free layer1234. That the magnetization direction of the pinning layer1231is parallel to the stacking direction of the layers in the MTJ may be that the magnetization direction of the pinning layer1231is the same as the stacking direction of the layers in the MTJ, in other words, the magnetization direction of the pinning layer1231is the direction from the pinning layer1231to the free layer1234. Alternatively, that the magnetization direction of the pinning layer1231is parallel to the stacking direction of the layers in the MTJ may be that the magnetization direction of the pinning layer1231is parallel to and opposite to the stacking direction of the layers in the MTJ, in other words, the magnetization direction of the pinning layer1231is a direction from the free layer1234to the pinning layer1231.

In addition, the reference layer1232is a film layer with a fixed magnetization direction in the MTJ. There is a strong ferromagnetic coupling effect between the pinning layer1231and the reference layer (which may also be referred to as a pinning layer)1232. A magnetization direction of the reference layer1232may be pinned by the pinning layer1231in a fixed direction, and the magnetization direction of the reference layer1232is difficult to change. The magnetization direction of the reference layer1232is the same as the magnetization direction of the pinning layer1231. Therefore, the magnetization direction of the reference layer1232is also parallel to the stacking direction of the layers in the MTJ. In addition, the pinning layer1231is configured to pin the magnetization direction of the reference layer1232in the fixed direction. Therefore, the magnetization direction of the pinning layer1231should not be prone to change, in other words, the pinning layer1231should have a large coercive field. However, the reference layer1232and the free layer1234are in a decoupled state due to an effect of the tunneling layer1233. Therefore, a magnetization direction of the free layer1234is prone to change under an effect of an external magnetic field, and the magnetization direction of the free layer1234may be parallel to or oppositely parallel to the magnetization direction of the reference layer1232, in other words, the magnetization direction of the free layer1234may be the same as or opposite to the magnetization direction of the reference layer1232.

Based on the foregoing descriptions, because magnetization directions of the pinning layer1231, the reference layer1232, and the free layer1234are all parallel to the stacking direction of the layers in the MTJ, the MTJ in this embodiment of this application is an MTJ with perpendicular magnetic anisotropy (perpendicular magnetic anisotropy, PMA).

The reference layer1232and the free layer1234are magnetic layers. For example, materials of the reference layer1232and the free layer1234include one or more of a cobalt-ferroboron (CoFeB) alloy, a ferrocobalt (CoFe) alloy, or a nickel-ferrocobalt (NiFeCo) alloy. For example, the materials of the reference layer1232and the free layer1234are the CoFeB alloy. Specifically, the materials of the reference layer1232and the free layer1234may be (CoxFe1-x)1-yBy, where both x and y are between 0 and 0.30.

The tunneling layer1233is a non-magnetic layer. For example, a material of the tunneling layer1233includes one or more of magnesium oxide (MgO) or aluminum oxide (Al2O3).

To facilitate growth of the pinning layer1231, in some embodiments, as shown inFIG.3b, the MTJ element12further includes a seed (seed) layer1235disposed between the second electrode122and the pinning layer1231, and the pinning layer1231may be grown on the seed layer1235.

A material of the reference layer1232is usually in a001lattice orientation, and a material of the pinning layer1231is usually in a111lattice orientation. In view of this, because a lattice difference between the reference layer1232and the pinning layer1231is large, it is difficult to grow the reference layer1232on the pinning layer1231, and roughness accumulation, stress accumulation, and the like are caused. Based on this, in some embodiments, as shown inFIG.3b, the MTJ element12further includes a structure conversion layer1236disposed between the reference layer1232and the pinning layer1231, and a material of the structure conversion layer1236is an amorphous material.

The material of the structure conversion layer1236disposed between the reference layer1232and the pinning layer1231is the amorphous material, and the amorphous material has no fixed lattice orientation. Therefore, growing the reference layer1232on the structure conversion layer1236can avoid a growth difficulty caused by a lattice difference, and avoid problems such as roughness accumulation and stress accumulation.

For example, the material of the structure conversion layer1236is one or more of tantalum (Ta), a tantalum alloy, or a tantalum-tungsten alloy. The tantalum is an amorphous material.

On this basis, in some embodiments, as shown inFIG.3b, the MTJ element12further includes a capping (capping) layer1237that is in contact with the free layer1234and that is disposed on a side that is of the free layer1234and away from the tunneling layer1233. Herein, after the capping layer1237is added, an interface between the capping layer1237and the free layer1234helps increase perpendicular magnetic anisotropy of the free layer1234, so that data storage time can be prolonged.

For example, a material of the capping layer1237includes magnesium oxide.

It should be understood that the tunneling layer1233is located between the reference layer1232and the free layer1234. When data stored in the MTJ element12is read, more than 90% of tunnel magneto resistance (tunneling magneto resistance, TMR) of the MTJ element12is from the tunneling layer1233. Therefore, resistance of the tunneling layer1233should be set to be large. In addition, the capping layer1237is located on the side that is of the free layer1234and that is away from the tunneling layer1233, and in addition to increasing the perpendicular magnetic anisotropy of the free layer1234, the capping layer1237is further configured to transmit a current. Therefore, resistance of the capping layer1237should be set to be small. In other words, the resistance of the tunneling layer1233is far greater than the resistance of the capping layer1237. When both the material of the tunneling layer1233and the material of the capping layer1237are magnesium oxide, because the resistance of the tunneling layer1233is far greater than the resistance of the capping layer1237, thickness of the capping layer1237may be adjusted to be small, so that the resistance of the capping layer1237is small. Certainly, magnesium oxide may alternatively be formed in a manner of magnesium oxidation and growth, and resistance of the formed magnesium oxide is small. A key to implementing reading/writing of the magnetic random access memory is that the magnetic random access memory has large tunnel magneto resistance and has high spin transfer efficiency. The foregoing MTJ structure in this application can obtain large tunnel magneto resistance (ranging from 150% to 250%) and has high spin transfer efficiency (>0.8). Therefore, reading and writing functions can be ensured.

Based on the structure of the memory10, the following uses a storage unit11as an example to describe a working process of the memory10.

When the storage unit11performs writing, the transistor T is in a conducted state. When a current flows from the free layer1234to the reference layer1232, to be specific, a spin electron flows from the reference layer1232to the free layer1234, and the spin electron passes through the reference layer1232, the electron in the current is spin-polarized along the magnetization direction of the reference layer1232, and a spin magnetic moment of the electron is parallel to the magnetization direction of the reference layer1232. When the electron passes through the tunneling layer1233and reaches the free layer1234, the spin electron transfers a spin moment (also referred to as a spin angular momentum, namely, an STT) to the free layer1234, and the free layer1234subject to a spin moment effect has small magnetization strength. Therefore, the magnetization direction of the free layer1234can freely change based on a polarization direction of the spin electron in the spin current, and finally the magnetization direction of the free layer1234is parallel to the magnetization direction of the reference layer1232, in other words, the magnetization direction of the free layer1234is the same as the magnetization direction of the reference layer1232, which may indicate that written information is “0”.

When a current flows from the reference layer1232to the free layer1234, to be specific, spin electrons flow from the free layer1234to the reference layer1232, the spin electrons perform exchange coupling with a magnetic moment in the reference layer1232, so that an electron that spins parallel to the magnetization direction of the reference layer1232passes through, and an electron that spins oppositely parallel to the magnetization direction of the reference layer1232is reflected. The reflected electron passes through the tunneling layer1233and reaches the free layer1234, and performs exchange coupling with a magnetic moment of the free layer1234, so that the magnetization direction of the free layer1234rotates in a direction opposite to the magnetization direction of the reference layer1232, and finally the magnetization direction of the free layer1234is oppositely parallel to the magnetization direction of the reference layer1232, in other words, the magnetization direction of the free layer1234is opposite to the magnetization direction of the reference layer1232, which may indicate that written information is “1”. A direction of the current herein may be controlled by using voltages provided by the bit line BL and the source line SL. When a voltage provided by the bit line BL is greater than a voltage provided by the source line SL, the current flows from the free layer1234to the reference layer1232; or when a voltage provided by the bit line BL is less than a voltage provided by the source line SL, the current flows from the reference layer1232to the free layer1234.

When the storage unit11performs reading, a constant small current flows out from the bit line BL to the drain of the conducted transistor T through the MTJ, and a potential difference is generated at two ends of the MTJ. Resistance of the MTJ may be determined based on a value of the potential difference, in other words, a relative orientation relationship between the magnetization direction of the free layer1234and the magnetization direction of the reference layer1232may be obtained, to determine that information stored in the storage unit11is “0” or “1”. Specifically, if the MTJ presents low resistance, the magnetization direction of the free layer1234is parallel to the magnetization direction of the reference layer1232, and information stored in the storage unit11is “0”. If the MTJ presents high resistance, the magnetization direction of the free layer1234is oppositely parallel to the magnetization direction of the reference layer1232, and information stored in the storage unit11is “1”.

It should be understood that, when the memory10stores information and reads information, the word line control circuit provides a gating signal to the word lines row by row, so that transistors T in a plurality of rows of storage units11are conducted row by row, and information can be written or read row by row.

Based on a working principle of the storage unit11, the memory10provided in this embodiment of this application may also be referred to as a spin transfer torque magnetic random access memory.

With reference toFIG.4a,FIG.5a, andFIG.6a, the memory10may further include a substrate13. The transistor T, the MTJ element12, and another pattern are all disposed on the substrate13. InFIG.4a,FIG.5a, andFIG.6a, an example in which the transistor is a MOS transistor is used for illustration. A source141, a drain142, an active layer143, and a gate144of the transistor T are illustrated, and a gate insulation layer disposed between the gate144and the active layer143is not illustrated.

It should be understood that, in a manufacturing process of the memory10, after the transistor T is manufactured on the substrate13, the MTJ element12is not directly manufactured. Usually, after the transistor T is manufactured and before the MTJ element12is manufactured, another conductive functional pattern and an insulation layer (FIG.4a,FIG.5a, andFIG.6ado not show the conductive functional pattern and the insulation layer) are further formed. Based on this, to electrically connect the drain142of the transistor T to the second electrode122of the MTJ element12, as shown inFIG.4a,FIG.5a, andFIG.6a, on a current transmission path between the drain142of the transistor T and the MTJ element12, at least one conductive structure15(also referred to as a conductive tube or a metal conductive tube) is connected in series between the second electrode122and the drain142of the transistor T, and the second electrode122is electrically connected to the drain142of the transistor T by using the at least one conductive structure15. Similarly, after the MTJ element12is manufactured and before the bit line BL is manufactured, a conductive functional pattern and an insulation layer are also formed. Based on this, to electrically connect the first electrode121to the bit line BL, as shown inFIG.4a,FIG.5a, andFIG.6a, on a current transmission path between the MTJ element12and the bit line BL, at least one conductive structure15is connected in series between the first electrode121and the bit line BL, and the first electrode121is electrically connected to the bit line BL by using the at least one conductive structure15. The conductive structure15and the conductive functional pattern may be synchronously formed.

Based on this, as shown inFIG.4a,FIG.5a, andFIG.6a, the memory10provided in this embodiment of this application further includes a first magnetic structure16disposed on the current transmission path and in contact with the MTJ element12. An included angle between a magnetization direction of the first magnetic structure16and the magnetization direction of the pinning layer1231is (90°, 180° ]. In other words, the included angle between the magnetization direction of the first magnetic structure16and the magnetization direction of the pinning layer1231is greater than 90° and less than or equal to 180°.

Compared with a current technology, in this embodiment of this application, the first magnetic structure16in contact with the MTJ element12is added to the current transmission path between the source141or the drain142of the transistor T and the bit line BL.

It should be understood that the first magnetic structure16is conductive because the first magnetic structure16is disposed on the current transmission path between the source141or the drain142of the transistor T and the bit line BL.

Herein, the memory10may include one first magnetic structure16that is in contact with the MTJ element12. In this case, as shown inFIG.4aandFIG.4b, the first magnetic structure16is connected between the MTJ element12and the source141or the drain142of the transistor T. Alternatively, as shown inFIG.5aandFIG.5b, the first magnetic structure16is connected between the MTJ element12and the bit line BL. The memory10may alternatively include two first magnetic structures16that are in contact with the MTJ element12. In this case, as shown inFIG.6aandFIG.6b, one first magnetic structure16is connected between the MTJ element12and the source141or the drain142of the transistor T, and the other first magnetic structure16is connected between the MTJ element12and the bit line BL.

It should be understood that, before the memory10is delivered from a factory, magnetization directions of the layers in the MTJ need to be initialized. To ensure that the included angle between the magnetization direction of the first magnetic structure16and the magnetization direction of the pinning layer1231is (90°, 180° ] after initialization, coercive force of the first magnetic structure16is different from coercive force of the pinning layer1231. For example, the first magnetic structure16is connected between the MTJ element12and the bit line BL, the first magnetic structure16is in contact with the first electrode121in the MTJ element12, and the magnetization direction of the first magnetic structure16is opposite to the magnetization direction of the pinning layer1231after initiation. A specific process of initializing the MTJ is as follows: First, as shown inFIG.7, a large first external magnetic field is applied, to enable magnetization directions of the pinning layer1231, the reference layer1232, the free layer1234, and the first magnetic structure16to be the same. Then, as shown inFIG.5b, a small second external magnetic field is applied, where a magnetic field direction of the first external magnetic field is opposite to a magnetic field direction of the second external magnetic field, and the second external magnetic field enables a magnetization direction of a layer with small coercive force to be flipped in an opposite direction, so that the magnetization direction of the first magnetic structure16is opposite to the magnetization direction of the pinning layer1231. InFIG.5bandFIG.7, an example in which the coercive force of the first magnetic structure16is less than the coercive force of the pinning layer1231is used for illustration.

In some embodiments, a material of the first magnetic structure16includes one or more of monatomic cobalt (Co), monatomic iron (Fe), monatomic nickel (Ni), and an alloy including at least one of cobalt, iron, or nickel.

The alloy including at least one of cobalt, iron, or nickel may be, for example, a CoB (cobalt-boron) alloy or a FeB (ferro-boron) alloy.

It may be understood that a material of the conductive structure15in the memory10is a non-magnetic material, for example, copper (Cu).

In some embodiments of this application, the first magnetic structure16may be formed by using a hole filling process. A specific process is as follows: First, an insulation layer is formed, where the insulation layer includes a via (via). Then, a magnetic film is deposited. Next, a magnetic film outside the via is polished, to form the first magnetic structure16in the via.

It should be noted that the conductive structure15inFIG.4a,FIG.5a, andFIG.6aincludes a first conductive part151and a second conductive part152. A reason is as follows: When the conductive structure15is manufactured, an insulation layer is formed first, where the insulation layer includes a via. Next, a conductive film is formed, where a part, of the conductive film, deposited in the via of the insulation layer is referred to as the first conductive part151. The conductive film is patterned to form the foregoing conductive functional pattern. In addition, a part formed after the conductive film deposited above the via is patterned is referred to as the second conductive part152.

In addition, when the memory10includes a conductive structure15connected between the MTJ element12and the bit line BL and in contact with the MTJ element12, the conductive structure15may be shown inFIG.4a, and includes a first conductive part151and a second conductive part152. For a specific manufacturing process, refer to the foregoing descriptions, and details are not described herein again.

When the memory10includes a conductive structure15connected between the MTJ element12and the source141or the drain142of the transistor T and in contact with the MTJ element12, the conductive structure15may include a first conductive part151, but does not include a second conductive part152. A specific manufacturing process is as follows: First, an insulation layer is formed, where the insulation layer includes a via. Then, a conductive film is formed. Next, a conductive film outside the via is removed (for example, polished), and a part, of the conductive film, deposited in the via of the insulation layer forms the first conductive part151, that is, the conductive structure15. The conductive structure15may alternatively be shown inFIG.5a, including a first conductive part151and a second conductive part152. For a specific manufacturing process, refer to the foregoing descriptions. Details are not described herein again.

When the memory10includes the first magnetic structure16connected between the MTJ element12and the bit line BL and in contact with the MTJ element12, after the first magnetic structure16is formed, a process of forming the conductive structure15may be shown inFIG.5aandFIG.6a. A conductive film is formed, and the conductive film is patterned to form the conductive structure15. Alternatively, an insulation layer may be formed first, where the insulation layer includes a via. Then, a conductive film is formed, where a part, of the conductive film, deposited in the via of the insulation layer forms the first conductive part151of the conductive structure15. The conductive film is patterned to form the foregoing conductive functional pattern, and a part formed after the conductive film deposited above the via is patterned is the second conductive part152of the conductive structure15.

It may be understood that, because the included angle between the magnetization direction of the first magnetic structure16and the magnetization direction of the pinning layer1231is (90, 180° ], an included angle between a direction of a magnetic field generated by the first magnetic structure16at the free layer1234and a direction of a magnetic field (also referred to as a static magnetic field or a stray field) generated by the pinning layer1231at the free layer1234is (90, 180° ].

In addition, when the included angle between the direction of the magnetic field generated by the first magnetic structure16at the free layer1234and the direction of the magnetic field generated by the pinning layer1231at the free layer1234is 180°, that is, when the direction of the magnetic field generated by the first magnetic structure16at the free layer1234is opposite to the direction of the magnetic field generated by the pinning layer1231at the free layer1234, the magnetic field generated by the first magnetic structure16at the free layer1234can cancel the magnetic field generated by the pinning layer1231at the free layer1234, so that impact of the magnetic field generated by the pinning layer1231at the free layer1234on the free layer1234can be reduced. When the included angle between the direction of the magnetic field generated by the first magnetic structure16at the free layer1234and the direction of the magnetic field generated by the pinning layer1231at the free layer1234is (90°, 180°), in a direction opposite to the magnetization direction of the pinning layer1231, the first magnetic structure16generates a magnetic field component at the free layer1234, and the magnetic field component that is generated by the first magnetic structure16at the free layer1234and that is along the direction opposite to the magnetization direction of the pinning layer1231may cancel the magnetic field generated by the pinning layer1231at the free layer1234.

It should be noted that, to ensure that the magnetization direction of the first magnetic structure16can remain unchanged after an external magnetic field is removed, for example, the magnetization direction of the first magnetic structure16is parallel to the stacking direction of the layers in the MTJ, in other words, to enable the first magnetic structure16to have magnetic shape anisotropy, a length of the first magnetic structure16along a direction parallel to the stacking direction of the layers in the MTJ is greater than or equal to a length of the first magnetic structure16along a direction perpendicular to the stacking direction of the layers in the MTJ. When the first magnetic structure16is a cylinder, a height of the first magnetic structure16is greater than or equal to a diameter of the first magnetic structure16.

An embodiment of this application provides a memory10. The memory10includes a plurality of storage units11and bit lines BLs. The storage unit11includes a transistor T and an MTJ element12connected to the transistor T. The MTJ element12is disposed on a current transmission path between a source141or a drain142of the transistor T and the bit line BL. The MTJ element12includes a pinning layer1231, a reference layer1232, a tunneling layer1233, and a free layer1234that are stacked in sequence. A magnetization direction of the pinning layer1231is parallel to a stacking direction of layers in the MTJ. The memory10further includes a first magnetic structure16disposed on the current transmission path and in contact with the MTJ element12. An included angle between a magnetization direction of the first magnetic structure16and the magnetization direction of the pinning layer1231is (90°, 180° ]. Because the included angle between the magnetization direction of the first magnetic structure16and the magnetization direction of the pinning layer1231is (90°, 180° ], a magnetic field generated by the first magnetic structure16at the free layer1234can cancel a magnetic field generated by the pinning layer1231at the free layer1234, so that a compensation field generated by the free layer1234can be reduced or eliminated. In this way, a current required for flipping the free layer1234is reduced, and a problem of flipping asymmetry (to be specific, magnitudes of currents required when a magnetization direction of the free layer is enabled to change to two opposite directions are different) in the MTJ can be resolved. In addition, because the magnetic field generated by the pinning layer1231at the free layer1234may be canceled by the magnetic field generated by the first magnetic structure16at the free layer1234, a difference caused by impact of a stray field on the free layer1234does not need to be overcome by increasing a current. In this way, the magnetization direction of the free layer1234can be flipped by using a small current, so that power can be reduced, durability of the MTJ can be improved, and a lifespan of the MTJ can be improved.

In some embodiments, the magnetization direction of the first magnetic structure16is opposite to the magnetization direction of the pinning layer1231, in other words, the included angle between the magnetization direction of the first magnetic structure16and the magnetization direction of the pinning layer1231is 180°, and a magnitude of the magnetic field generated by the first magnetic structure16at the free layer1234is the same as that of the magnetic field generated by the pinning layer1231at the free layer1234.

When the magnetization direction of the first magnetic structure16is opposite to the magnetization direction of the pinning layer1231, and the magnitude of the magnetic field generated by the first magnetic structure16at the free layer1234is the same as that of the magnetic field generated by the pinning layer1231at the free layer1234, the magnetic field generated by the first magnetic structure16at the free layer1234can cancel the magnetic field generated by the pinning layer1231at the free layer1234. Therefore, a magnetic field, generated by another layer, applied to the free layer1234is zero or approaches zero, and a compensation field generated by the free layer1234due to the magnetic field generated by the another layer is zero or approaches zero. This further reduces the current required for flipping the free layer1234, and more effectively resolves the problem of flipping asymmetry in the MTJ.

Considering that the reference layer1232may also generate a stray field at the free layer1234, to prevent the stray field generated by the reference layer1232at the free layer1234from increasing the current required for flipping the free layer1234, in some embodiments, the magnetization direction of the first magnetic structure16is opposite to the magnetization direction of the pinning layer1231. In addition, the magnitude of the magnetic field generated by the first magnetic structure16at the free layer1234is the same as magnitudes of magnetic fields generated by the pinning layer1231and the reference layer1232at the free layer1234. In this way, both the magnetic fields generated by the pinning layer1231and the reference layer1232at the free layer1234can be canceled by the magnetic field generated by the first magnetic structure16at the free layer1234. This further reduces the current required for flipping the free layer1234.

Refer toFIG.8aandFIG.8b.FIG.8ais a schematic diagram of simulation. A block inFIG.8arepresents the first magnetic structure16. The magnetization direction of the first magnetic structure16is parallel to the stacking direction of the layers in the MTJ.FIG.8ashows a direction of a magnetic field in the first magnetic structure16and a direction of a stray field generated externally. InFIG.8a, an arrow is used to represent a magnetic field direction of space in which the first magnetic structure16is located, and the magnetic field direction of the space in which the first magnetic structure16is located includes the direction of the magnetic field in the first magnetic structure16and the direction of the stray field generated externally. InFIG.8a, a black straight line A is parallel to the stacking direction of the layers in the MTJ, and a direction of a magnetic field in a central area of the first magnetic structure16is parallel to the stacking direction of the layers in the MTJ. It can be learned along a location shown by the black straight line A inFIG.8athat the direction of the magnetic field in the first magnetic structure16is opposite to the direction of the stray field generated externally.FIG.8bis a simulation result diagram of locations shown by a black straight line A (that is, a Z axis) and a black straight line B (that is, an X axis) inFIG.8a. A horizontal coordinate represents a location of the X axis or the Z axis, where a point a inFIG.8arepresents that a location of the Z axis is −5.00E-08, and a point b inFIG.8arepresents that a location of the X axis is −5.00E-08. A vertical coordinate inFIG.8brepresents magnetic field (magnetic field) intensity, where a unit is oersted (Oe). It can be learned fromFIG.8bof a change of magnetic field intensity Hx along the X axis and a change of magnetic field intensity Hz along the Z axis. For example, the MTJ is located above the first magnetic structure16. A location P inFIG.8arepresents a location of the free layer1234, and a location of the free layer1234on the Z axis is 20 nm. It can be learned from a simulation result provided inFIG.8bthat the first magnetic structure16generates a stray field of approximately 900 Oe to 2000 Oe at the location P, and a direction of the stray field is opposite to the direction of the magnetic field in the first magnetic structure16. Based on this, the stray field generated by the first magnetic structure16may be used to cancel the stray field generated by the pinning layer1231.

In a current technology, to avoid problems such as a large current required for flipping the free layer1234in the MTJ and flipping asymmetry in the MTJ that are caused by a large compensation field of the free layer1234caused by a strong stray field generated by the pinning layer1231, as shown inFIG.9, an artificial antiferromagnetic layer is used for the pinning layer1231. The artificial antiferromagnetic layer includes a first pinning sub-layer1231a, a non-magnetic layer1231b, and a second pinning sub-layer1231cthat are stacked, and magnetization directions of the first pinning sub-layer1231aand the second pinning sub-layer1231care opposite. The first pinning sub-layer1231ais more close to the reference layer1232relative to the second pinning sub-layer1231c, and a magnetization direction of the reference layer1232is the same as a magnetization direction of the first pinning sub-layer1231a. Because the magnetization directions of the first pinning sub-layer1231aand the second pinning sub-layer1231care opposite, the stray field generated by the pinning layer1231may approach 0. In this way, the problems of the large current required for flipping the free layer1234and the flipping asymmetry in the MTJ can be avoided.

However, as shown inFIG.10, because both the first pinning sub-layer1231aand the second pinning sub-layer1231care formed by a plurality of layers of films that are alternately stacked by a ferromagnetic (ferromagnetic, FM) layer such as a cobalt (Co) layer and a heavy metal (heavy metal, HM) layer such as a platinum (Pt) layer, a structure of the pinning layer1231is complex, roughness or stress accumulation is easily caused, and thickness of the MTJ is large, which are not conducive to miniaturization of the MTJ. In addition, thickness of the pinning layer1231is large, and the pinning layer1231is a conductive material, in other words, thickness of a conductive material below the tunneling layer1233is large. In this way, resputtering is easily caused in an etching process, and the conductive material is sputtered to a side surface of the tunneling layer1233. Therefore, an MTJ short circuit is caused, and an engineering yield is reduced.

In this embodiment of this application, the stray field generated by the pinning layer1231at the free layer1234may be canceled by the stray field generated by the first magnetic structure16at the free layer1234. Therefore, the thickness of the pinning layer1231may be set to be small. Based on this, to reduce the thickness of the pinning layer1231, in some embodiments of this application, as shown inFIG.10, the pinning layer1231includes a ferromagnetic layer and a heavy metal layer (that is, a non-magnetic layer) that are alternately stacked along the stacking direction of the layers in the MTJ.

In some embodiments, a material of the ferromagnetic layer includes one or more of monatomic cobalt, monatomic iron, monatomic nickel, and an alloy including at least one of cobalt, iron, or nickel.

In some embodiments, a material of the heavy metal layer includes one or more of monatomic platinum (Pt), monatomic tantalum, monatomic copper (Cu), monatomic iridium (Ir), monatomic ruthenium (Ru), monatomic tungsten (W), and an alloy including at least one of platinum, tantalum, copper, iridium, ruthenium, or tungsten.

For example, the pinning layer1231includes a cobalt layer and a platinum layer ([Co/Pt]n, where n is a positive integer, and represents a quantity of cobalt layers or a quantity of platinum layers) that are alternately stacked along the stacking direction of the layers in the MTJ.

Compared with the current technology in which the pinning layer1231includes the first pinning sub-layer1231a, the non-magnetic layer1231b, and the second pinning sub-layer1231c, and the first pinning sub-layer1231aand the second pinning sub-layer1231ceach include a ferromagnetic layer and a heavy metal layer that are alternately stacked along the stacking direction of the layers in the MTJ, in this embodiment of this application, because the stray field generated by the pinning layer1231at the free layer1234may be canceled by the stray field generated by the first magnetic structure16at the free layer1234, the pinning layer1231may include only the ferromagnetic layer and the heavy metal layer that are alternately stacked along the stacking direction of the layers in the MTJ, in other words, the pinning layer1231in this embodiment of this application includes only the first pinning sub-layer1231ain the current technology. Therefore, compared with the current technology, in this embodiment of this application, the thickness of the pinning layer1231is greatly reduced, and a structure is simplified. This helps reduce roughness of an interface between the tunneling layer1233and the free layer1234, reduce stress accumulation, and facilitate miniaturization of the MTJ. In addition, because the thickness of the pinning layer1231is greatly reduced, in other words, thickness of a conductive material below the tunneling layer1233is reduced, a probability of a short circuit caused by resputtering in an etching process is reduced, and an engineering yield is improved.

In some other embodiments of this application, a material of the pinning layer1231is a perpendicular magnetic anisotropy material.

When the material of the pinning layer1231is the perpendicular magnetic anisotropy material, in some embodiments, the material of the pinning layer1231includes one or more of a ferroplatinum (FePt) alloy and a cobalt-platinum (CoPt) alloy.

Because the material of the pinning layer1231is the perpendicular magnetic anisotropy material, the magnetization direction of the pinning layer1231is easily magnetized to be parallel to the stacking direction of the layers in the MTJ. In this way, thickness of the pinning layer1231may be set to be small. Therefore, compared with a current technology, in this embodiment of this application, the thickness of the pinning layer1231is greatly reduced, and a structure is simplified. This helps reduce roughness of an interface between the tunneling layer1233and the free layer1234, reduce stress accumulation, and facilitate miniaturization of the MTJ. In addition, because the thickness of the pinning layer1231is greatly reduced, in other words, thickness of a conductive material below the tunneling layer1233is reduced, a probability of a short circuit caused by resputtering in an etching process is reduced, and an engineering yield is improved.

Based on the foregoing descriptions, in some embodiments, as shown inFIG.11aandFIG.12a, the memory10further includes a second magnetic structure17disposed on the current transmission path, and a direction of a magnetic field generated by the second magnetic structure17at the free layer1234is not parallel to the magnetization direction of the free layer1234.

As shown inFIG.12aandFIG.12b, the first magnetic structure16is connected between the MTJ element12and the source141or the drain142of the transistor T, and the second magnetic structure17is connected between the MTJ element12and the bit line BL. Alternatively, as shown inFIG.11aandFIG.11b, the first magnetic structure16is connected between the MTJ element12and the bit line BL, and the second magnetic structure17is connected between the MTJ element12and the source141or the drain142of the transistor T.

It should be noted that, dashed curves inFIG.11a,FIG.11b,FIG.12a, andFIG.12brepresent magnetic lines of the second magnetic structure17.

Herein, a process of forming the second magnetic structure17may be the same as the foregoing process of forming the first magnetic structure16. Reference may be made to the foregoing descriptions, and details are not described herein again.

It should be understood that, because the second magnetic structure17is disposed on the current transmission path between the source141or the drain142of the transistor T and the bit line BL, the second magnetic structure17is conductive.

The following provides two implementations as examples, to enable the direction of the magnetic field generated by the second magnetic structure17at the free layer1234to be not parallel to the magnetization direction of the free layer1234.

In a first implementation, as shown inFIG.4a,FIG.5a, andFIG.6a, the memory further includes a connection layer18disposed between the second magnetic structure17and the MTJ element12. The second magnetic structure17is electrically connected to the MTJ element12through the connection layer18. A projection of the MTJ element12on the connection layer18does not overlap at least a part of areas of a projection of the second magnetic structure17on the connection layer18.

In this implementation, in some embodiments, a magnetization direction of the second magnetic structure17is parallel to the stacking direction of the layers in the MTJ.

It should be noted that, to ensure that the magnetization direction of the second magnetic structure17can remain unchanged after an external magnetic field is removed, for example, the magnetization direction of the second magnetic structure17is parallel to the stacking direction of the layers in the MTJ, in other words, to enable the second magnetic structure17to have magnetic shape anisotropy, a length of the second magnetic structure17along a direction parallel to the stacking direction of the layers in the MTJ is greater than or equal to a length of the second magnetic structure17along a direction perpendicular to the stacking direction of the layers in the MTJ. When the second magnetic structure17is a cylinder, a height of the second magnetic structure17is greater than or equal to a diameter of the second magnetic structure17.

On this basis, the direction of the magnetic field generated by the second magnetic structure17at the free layer1234may be adjusted by adjusting the magnetization direction of the second magnetic structure17and relative locations of the MTJ element12and the second magnetic structure17in the direction perpendicular to the stacking direction of the layers in the MTJ.

In addition, in some examples, the projection of the MTJ element12on the connection layer18overlaps a part of areas of the projection of the second magnetic structure17on the connection layer18, and does not overlap a part of areas of the projection of the second magnetic structure17on the connection layer18. In some other examples, the projection of the MTJ element12on the connection layer18does not overlap the projection of the second magnetic structure17on the connection layer18, in other words, there is no overlapping area between the projection of the MTJ element12on the connection layer18and the projection of the second magnetic structure17on the connection layer18. In the accompanying drawings of embodiments of this application, an example in which there is no overlapping area between the projection of the MTJ element12on the connection layer18and the projection of the second magnetic structure17on the connection layer18is used for illustration.

In a second implementation, the second magnetic structure17is in contact with the MTJ element12, and a magnetization direction of the second magnetic structure17is perpendicular to the stacking direction of the layers in the MTJ.

Herein, that the stacking direction of the layers in the MTJ is a vertical direction is used as an example, and the magnetization direction of the second magnetic structure17may be a horizontal-left direction, or may be a horizontal-right direction.

It should be understood that, when the magnetization direction of the second magnetic structure17is perpendicular to the stacking direction of the layers in the MTJ, the direction of the magnetic field generated by the second magnetic structure17at the free layer1234is perpendicular to the stacking direction of the layers in the MTJ.

It should be noted that, to ensure that the magnetization direction of the second magnetic structure17can remain unchanged and can still be perpendicular to the stacking direction of the layers in the MTJ after an external magnetic field is removed, in other words, to enable the second magnetic structure17to have magnetic shape anisotropy, a length of the second magnetic structure17along a direction perpendicular to the stacking direction of the layers in the MTJ is greater than or equal to a length of the second magnetic structure17along a direction parallel to the stacking direction of the layers in the MTJ. When the second magnetic structure17is a cylinder, a diameter of the second magnetic structure17is greater than or equal to a height of the second magnetic structure17.

It should be understood that, when the direction of the magnetic field generated by the second magnetic structure17at the free layer1234is perpendicular to the magnetization direction of the free layer1234, and the free layer1234is flipped, the magnetic field generated by the second magnetic structure17at the free layer1234may apply magnetic field force to the free layer1234, to facilitate flipping of the free layer1234. When the direction of the magnetic field generated by the second magnetic structure17at the free layer1234is not parallel to and is not perpendicular to the magnetization direction of the free layer1234, and the free layer1234is flipped, a magnetic field component (also referred to as an in-plane component) of the magnetic field generated by the second magnetic structure17at the free layer1234in the direction perpendicular to the stacking direction of the layers in the MTJ, namely, a net in-plane field generated by the second magnetic structure17at the free layer1234, may apply magnetic field force to the free layer1234, to facilitate flipping of the free layer1234.

In this embodiment of this application, because the direction of the magnetic field generated by the second magnetic structure17at the free layer1234is not parallel to the magnetization direction of the free layer1234, the magnetic field generated by the second magnetic structure17at the free layer1234may apply magnetic field force to the free layer1234. This facilitates flipping of the free layer1234. In this way, the current required for flipping the free layer1234is reduced, STT incubation time (incubation time) is reduced, and a flipping speed of the free layer1234is increased.

On this basis, in some examples, the direction of the magnetic field generated by the second magnetic structure17at the free layer1234is perpendicular to the magnetization direction of the free layer1234.

It should be understood that, when the magnetization direction of the second magnetic structure17is parallel to the stacking direction of the layers in the MTJ, relative locations of the MTJ element12and the second magnetic structure17in the direction perpendicular to the stacking direction of the layers in the MTJ are adjusted, to enable the direction of the magnetic field generated by the second magnetic structure17at the free layer1234to be perpendicular to the magnetization direction of the free layer1234. When the magnetization direction of the second magnetic structure17is parallel to the stacking direction of the layers in the MTJ, the magnetization direction of the second magnetic structure17may be the same as the magnetization direction of the pinning layer1231, or may be opposite to the magnetization direction of the pinning layer1231.

When the direction of the magnetic field generated by the second magnetic structure17at the free layer1234is perpendicular to the magnetization direction of the free layer1234, the magnetic field generated by the second magnetic structure17at the free layer1234is more conducive to flipping of the free layer1234. Therefore, the current required for flipping the free layer1234can be further reduced, the STT incubation time can be further reduced, and the flipping speed of the free layer1234can be more effectively improved.

With reference toFIG.8a, a block inFIG.8arepresents the second magnetic structure17, and the magnetization direction of the second magnetic structure17is parallel to the stacking direction of the layers in the MTJ. It can be learned from a location shown by a black straight line B inFIG.8athat, on a plane at the location shown by the black straight line B, an in-plane stray field (that is, a stray field whose magnetic field direction is perpendicular to the stacking direction of the layers in the MTJ) may be generated on two sides above the second magnetic structure17.FIG.13is a simulation result diagram of the plane at the location shown by the black straight line B inFIG.8a, and a dashed circle inFIG.13represents the MTJ. It can be learned fromFIG.13that, on the plane at the location shown by the black straight line B inFIG.8a, an in-plane stray field whose absolute value is about 300 Oe to 800 Oe is generated on two sides above the second magnetic structure17, and the free layer1234may be flipped by using the stray field. In addition, a magnitude of the in-plane stray field, generated by the second magnetic structure17, applied to the MTJ may be selected by moving the MTJ (the dashed circle inFIG.13), in other words, the magnitude of the in-plane stray field, generated by the second magnetic structure17, applied to the MTJ may be adjusted by adjusting relative locations of the MTJ and the second magnetic structure17in a horizontal direction.

The current Jthrequired for flipping the free layer1234may be calculated according to the following formula:

where HXis an in-plane field generated by the second magnetic structure17at the free layer1234(in other words, the direction of the magnetic field generated by the second magnetic structure17at the free layer1234is perpendicular to the stacking direction of the layers in the MTJ), HK,effis an effective anisotropy field, MSis saturated magnetization strength, tFis thickness of the free layer1234, e is an electron constant, a is a magnetic damping (magnetic damping) factor, h is a Planck constant, and η is spin transfer efficiency.

It can be learned from the foregoing formula that, the in-plane field generated by the second magnetic structure17at the free layer1234can significantly reduce a magnitude of the current required for flipping the free layer1234. In addition, when the in-plane field acts in the magnetization direction of the free layer1234, a thermal disturbance effect is enhanced, the STT incubation time is reduced, flipping of the free layer1234is accelerated, writing duration of the MTJ is reduced, and dynamic writing power consumption of the MTJ is further reduced.

It should be noted thatFIG.4a,FIG.4b,FIG.5a,FIG.5b,FIG.6a,FIG.6b,FIG.7,FIG.11a,FIG.11b,FIG.12a, andFIG.12bin the specification of this application show only a connection relationship and a location relationship between the MTJ element12and the first magnetic structure16or the second magnetic structure17, and do not limit a size relationship between the MTJ element12and the first magnetic structure16or the second magnetic structure17. Along the direction perpendicular to the stacking direction of the layers in the MTJ, a size of the first magnetic structure16or the second magnetic structure17may be greater than, equal to, or less than a size of the MTJ element12.

Based on this, an embodiment of this application further provides an electronic device. The electronic device includes a circuit board and a memory connected to the circuit board. The memory may be any memory provided above. The circuit board may be a printed circuit board (printed circuit board, PCB). Certainly, the circuit board may also be a flexible circuit board (flexible printed circuit board, FPC) or the like. The circuit board is not limited in this embodiment.

Optionally, the electronic device is different types of user equipment or terminal devices such as a computer, a mobile phone, a tablet computer, a wearable device, and a vehicle-mounted device. The electronic device may also be a network device such as a base station. Optionally, the electronic device further includes a package substrate, where the package substrate is fixed on the printed circuit board PCB by using a solder ball, and the memory is fixed on the package substrate by using a solder ball. It should be noted that, for details of related descriptions of the memory in the electronic device, refer to the descriptions of the memory in the foregoing embodiment. Details are not described in this embodiment of this application again.

On this basis, an embodiment of this application further provides a non-transitory computer-readable storage medium used together with a computer. The computer has software for creating an integrated circuit. The computer-readable storage medium stores one or more computer-readable data structures. The one or more computer-readable data structures have photomask data for manufacturing the memory provided in any figure provided above.