CN111725386B - A magnetic storage device and its manufacturing method, memory and neural network system - Google Patents

Abstract

The invention relates to a magnetic storage device, a method for making the same, a memory and a neural network system. The magnetic storage device comprises a free layer; the free layer comprises at least two ferromagnetic layers with variable magnetic moment directions and at least one decoupling layer, at least Each decoupling layer of one decoupling layer is disposed between two ferromagnetic layers of the at least two ferromagnetic layers, and the decoupling layer between the two ferromagnetic layers makes no coupling between the two ferromagnetic layers effect. In the magnetic memory device provided by the present application, when the direction of the magnetic moment of the ferromagnetic layer in the free layer changes, the magnetic memory device will have four or more than four magnetic moment states, and each magnetic moment state can represent a binary Logical information, in this way, can realize multi-value storage; in addition, when the magnetic storage device is applied to a neural network system, various weight coefficients in convolution calculation can be realized.

Description

A magnetic storage device and its manufacturing method, memory and neural network system

technical field

The present invention relates to the technical field of non-volatile storage and neural network, in particular to a magnetic storage device and a manufacturing method thereof, a memory and a neural network system.

Background technique

As shown in FIG. 1 , a magnetic memory device in the prior art generally consists of a buffer layer 110 , a pinning layer 210 , a reference layer 310 , a barrier layer 410 (or a space layer), a free layer 510 , and a hard mask layer 610 . Magnetic memory devices can be divided into two categories according to different magnetic anisotropy: in-plane magnetic anisotropy magnetic memory devices and perpendicular magnetic anisotropy magnetic memory devices.

The reference layer of the magnetic memory device is composed of a single or multi-layer ferromagnetic layer and a coupling layer between the ferromagnetic layers. The magnetic moment of the ferromagnetic material is firmly pinned and the direction is fixed; the free layer is composed of a single layer. Layer or double-layer ferromagnetic layers and coupling layers between the ferromagnetic layers are formed. Generally, the magnetic moments of all ferromagnetic layers in the free layer can be regarded as a whole, and the direction of the overall magnetic moment can be changed. Magnetic memory devices mainly have two magnetic moment states: when the magnetic moment directions of the free layer and the reference layer are in the same direction, the device presents a low resistance state; when the magnetic moment directions of the free layer and the reference layer are opposite, the device presents a high resistance state. Due to the above characteristics, it is often used as the core device of Magnetic Random Access Memory (MRAM), the low resistance state is used to represent the binary logic state "0", and the high resistance state is used to represent the binary logic state "1 ". This means that a magnetic storage device can only have one bit of information storage capacity, so how to increase the information storage capacity of each magnetic storage device is of great significance to improve the read-write efficiency and information storage density of MRAM.

SUMMARY OF THE INVENTION

The embodiments of the present application provide a magnetic storage device, a method for making the same, a memory, and a neural network system. The magnetic storage device can have multiple magnetic moment states, can realize the function of multi-value storage, and can realize multiple functions in convolution calculation. weight coefficients.

In one aspect, the present application provides a magnetic memory device including a free layer; the free layer includes at least two ferromagnetic layers with variable magnetic moment directions and at least one decoupling layer, each of which is decoupled in the at least one decoupling layer The layer is arranged between two ferromagnetic layers in the at least two ferromagnetic layers; the decoupling layer between the two ferromagnetic layers makes no coupling effect between the two ferromagnetic layers; wherein, the at least two ferromagnetic layers The composition and/or thickness of any two ferromagnetic layers are different; or, the free layer includes two or more decoupling layers, and the thickness of any two decoupling layers in the two or more decoupling layers is the sum of / or different ingredients.

In another aspect, the present application provides a method for fabricating a magnetic memory device, comprising sequentially depositing a buffer layer, a pinning layer, a reference layer and a barrier layer; depositing a free layer on the barrier layer; wherein the free layer includes at least two ferromagnetic layers with variable magnetic moment directions and at least one decoupling layer, any two of the at least two ferromagnetic layers have different compositions and/or thicknesses; or, the free layer includes two or more decoupling layers. A coupling layer, any two of the two or more decoupling layers having different thicknesses and/or compositions; annealing the free layer; depositing a hard mask layer on the free layer.

In another aspect, the present application provides a method for fabricating a magnetic memory device, comprising sequentially depositing a buffer layer, a pinning layer, a reference layer and a barrier layer; depositing a first ferromagnetic layer and a first decoupling on the barrier layer layer, performing the first annealing on the first ferromagnetic layer and the first decoupling layer; depositing a second ferromagnetic layer on the first decoupling layer, and performing the second annealing on the second ferromagnetic layer; wherein the first The annealing conditions of the second annealing are different from those of the second annealing, and the annealing conditions include annealing temperature, annealing time and annealing atmosphere; a hard mask layer is deposited on the second ferromagnetic layer.

On the other hand, the present application provides a memory, comprising a wire for generating a magnetic field, the above-mentioned magnetic storage device and a magnetic detection device; the magnetic storage device is used for presenting various magnetic moment states according to the magnetic field generated by the wire; the magnetic detection device uses for obtaining the magnetic moment state of a magnetic memory device.

On the other hand, the present application provides a neural network system, including a calculation unit, the calculation unit includes a wire for generating a magnetic field, the above-mentioned magnetic storage device, a magnetic detection device, and a resistive coupling device; one end of the resistive coupling device and the magnetic One end of the detection device is connected, and the other end of the resistive coupling device is connected to the other end of the magnetic detection device; among them, the magnetic storage device can present various magnetic moment states according to the magnetic field generated by the wire, and the synaptic weight of the neural network system corresponds to various A magnetic moment state in the magnetic moment state; the magnetic detection device is used to obtain the magnetic moment state of the magnetic storage device, so as to obtain the synaptic weight corresponding to the magnetic moment state.

A magnetic storage device and a manufacturing method thereof, a memory, and a neural network system provided by the embodiments of the present application have the following technical effects:

A magnetic memory device provided by the present application includes a free layer; the free layer includes at least two ferromagnetic layers with variable magnetic moment directions and at least one decoupling layer, and each decoupling layer in the at least one decoupling layer is provided in the Between two ferromagnetic layers in the at least two ferromagnetic layers; wherein, the composition and/or thickness of any two ferromagnetic layers in the at least two ferromagnetic layers are different; or, the free layer includes two or more Decoupling layers, any two of the two or more decoupling layers are different in thickness and/or composition. In the magnetic memory device provided by the present application, when the direction of the magnetic moment of the ferromagnetic layer in the free layer changes, it will cause the magnetic memory device to have four or more than four magnetic moment states, and each magnetic moment state can represent a binary Logic information, taking the free layer including two ferromagnetic layers as an example, the magnetic memory device can present four magnetic moment states, which can represent the binary logic information of "00", "01", "10", and "11" respectively. Implements binary storage for a device. The magnetic storage device provided by the present application can present four or more than four magnetic moment states, and each magnetic moment state can represent different binary logic information, thus, multi-value storage can be realized; in addition, the magnetic storage device is applied to neural networks system, which can realize various weight coefficients in convolution calculation.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present application more clearly, the following briefly introduces the drawings that are used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

1 is a schematic structural diagram of a magnetic storage device in the prior art;

FIG. 2 is a schematic structural diagram of a magnetic storage device provided by an embodiment of the present application;

3 is a schematic diagram of a magnetic moment state of a magnetic storage device provided in an embodiment of the present application;

FIG. 4 is a schematic diagram of a magnetic moment state of another magnetic memory device provided in an embodiment of the present application;

FIG. 5 is a schematic structural diagram of a decoupling layer provided by an embodiment of the present application;

FIG. 6 is a schematic structural diagram of another decoupling layer provided by an embodiment of the present application;

7 is a schematic structural diagram of a free layer provided by an embodiment of the present application;

8 is a schematic diagram of the relationship between the magnetic field direction and the voltage pulse of an Oersted magnetic field provided by an embodiment of the present application;

9 is a schematic diagram of a magnetic moment state of a magnetic memory device provided by an embodiment of the present application as a function of voltage pulses;

10 is a schematic diagram of the relationship between the magnetic field direction of another Oersted magnetic field and the voltage pulse provided by the embodiment of the present application;

FIG. 11 is a schematic diagram of a magnetic moment state of another magnetic memory device provided by an embodiment of the present application changing with a voltage pulse;

12 is a schematic structural diagram of a storage unit in a memory provided by an embodiment of the present application;

13 is a schematic structural diagram of a storage unit in a memory provided by an embodiment of the present application;

14 is a schematic structural diagram of a neural network computing module provided by an embodiment of the present application;

The following supplementary descriptions are provided for the accompanying drawings:

110-buffer layer; 210-pinning layer; 310-reference layer; 410-barrier layer;

510 free layer; 511 - ferromagnetic layer; 512 - ferromagnetic layer; 513 - decoupling layer; 5131 - first induction layer; 5132 - second induction layer;

610 - hard mask layer;

1200-magnetic memory device; 1201-SQUID device; 1202- solenoid; 1203-word line; 1204-word line; 1205-write/read bit line; 1206-write/read bit line;

1300 - magnetic storage device; 1301 - SQUID device; 1302 - write bit line; 1303 - write bit line; 1304 - word line; 1305 - read bit line; 1306 - read bit line;

1401-input wire; 1402-output wire, 1403-magnetic storage device; 1404-wire; 1405-magnetic detection device; 1406-resistive coupling element.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of this application.

Reference herein to "one embodiment" or "an embodiment" refers to a particular feature, structure, or characteristic that may be included in at least one implementation of the present application. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the purpose of It is convenient to describe the application and to simplify the description, rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the application. In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. Also, the terms "first," "second," etc. are used to distinguish between similar objects, and are not necessarily used to describe a particular order or precedence. It is to be understood that data so used may be interchanged under appropriate circumstances so that the embodiments of the application described herein can be practiced in sequences other than those illustrated or described herein.

Please refer to FIG. 2. FIG. 2 is a schematic structural diagram of a magnetic memory device provided by an embodiment of the present application, including a free layer 510;

The free layer 510 includes at least two ferromagnetic layers with variable magnetic moment directions and at least one decoupling layer, and each decoupling layer in the at least one decoupling layer is provided on two ferromagnetic layers in the at least two ferromagnetic layers between the two ferromagnetic layers; the decoupling layer between the two ferromagnetic layers makes no coupling effect between the two ferromagnetic layers; wherein the composition and/or thickness of any two of the at least two ferromagnetic layers are different; or , the free layer includes two or more decoupling layers, and any two of the two or more decoupling layers have different thicknesses and/or compositions.

In the embodiment of the present application, the free layer 510 includes two or more ferromagnetic layers and a decoupling layer between the ferromagnetic layers, and the thickness of the decoupling layer between the two ferromagnetic layers is greater than or equal to 5 nanometers. There is no coupling effect between the two ferromagnetic layers, and when the direction of the magnetic moment of a ferromagnetic layer changes, the direction of the magnetic moment of other ferromagnetic layers may not be affected. Wherein, the composition and/or thickness of any two ferromagnetic layers are different, so that the magnitudes of the magnetic anisotropy of each ferromagnetic layer are different from each other; or, the free layer includes two or more decoupling layers, and the two Different thicknesses and/or compositions of any two decoupling layers or two or more decoupling layers can also make the magnitude of the magnetic anisotropy of each ferromagnetic layer different from each other. According to the change of the magnetic moment direction of the ferromagnetic layer in the free layer 510, the magnetic memory device can present four or more than four magnetic moment states, and each magnetic moment state can represent a kind of binary logic information.

In the embodiment of the present application, the magnetic memory device further includes a buffer layer 110 , a pinning layer 210 , a reference layer 310 , a barrier layer 410 and a hard mask layer 610 , and the magnetic memory device is sequenced from bottom to top as the buffer layer 110 , the pinning layer layer 210 , reference layer 310 , barrier layer 410 , free layer 510 and hard mask layer 610 . The shape of the magnetic memory device may be a cylinder, an elliptical cylinder, an irregular cylinder, a cube, and a rectangular parallelepiped.

Please refer to FIG. 3 . FIG. 3 is a schematic diagram of a magnetic moment state of a magnetic memory device provided by an embodiment of the present application. In a magnetic memory device with perpendicular magnetic anisotropy, there are two ferromagnetic layers 511 and 512 in the free layer 510 . For example. The magnetic memory device can present four magnetic moment states, which represent binary logic information of "00", "01", "10", and "11" respectively, so that binary storage of a device can be realized. FIG. 4 is a schematic diagram of the magnetic moment state of another magnetic memory device provided by the embodiment of the present application. Taking the magnetic memory device with in-plane magnetic anisotropy and two ferromagnetic layers 511 and 512 in the free layer 510 as an example, The principle is the same as the above-mentioned perpendicular magnetic anisotropy magnetic memory device. The magnetic memory device provided by the present application can present four or more than four magnetic moment states, and each magnetic moment state can represent different binary logic information, so that multi-value storage can be realized. It should be noted that the lengths of the arrows in the ferromagnetic layers in the drawings are different, indicating that the magnitudes of the magnetic anisotropy of the ferromagnetic layers are different.

In the embodiment of the present application, the material of the decoupling layer 513 includes a metal material and/or an oxide material; wherein, the metal material includes a metal material doped with impurity particles and a metal material without impurity particle doping.

The above-mentioned metal material may include any one of Al, Cr, Mn, Cu, Zn, Ag and Au;

The above oxide material may include any one or more of MgO, Al ₂ O ₃ , AlO _x , BiFeO ₃ , NiO, CoO, Ni _0.5 Co _0.5 O, GdO _y and MgAl ₂ O ₄ .

Please refer to FIG. 5 , which is a schematic structural diagram of a decoupling layer provided by an embodiment of the present application.

Optionally, as shown in FIG. 5( a ), the decoupling layer 513 may only be a single-layer structure composed of any one of the above-mentioned metal materials.

Optionally, as shown in FIG. 5( b ), the decoupling layer 513 may also have a single-layer structure composed of only any one of the above oxide materials.

Optionally, as shown in FIG. 5( c ), the decoupling layer 513 may also be a multi-layer structure composed of the above-mentioned non-impurity particle-doped metal material and the above-mentioned oxide material.

Optionally, as shown in FIG. 5( d ), the decoupling layer 513 may also be a single-layer structure composed of any one of the above-mentioned metal materials doped with impurity particles.

In the embodiment of the present application, the thickness of each decoupling layer 513 is greater than or equal to 5 nanometers, so that the coupling strength between different ferromagnetic layers is substantially zero, and when the direction of the magnetic moment of one of the ferromagnetic layers changes, it does not affect the other The direction of the magnetic moment of the ferromagnetic layer.

Please refer to FIG. 6. FIG. 6 is a schematic structural diagram of another decoupling layer provided by an embodiment of the present application.

In this embodiment of the present application, the decoupling layer 513 in at least one decoupling layer includes a first inductive layer 5131 and/or a second inductive layer 5132 ; wherein the first inductive layer 5131 is located in the decoupling layer including the first inductive layer 5131 513, the second inductive layer 5132 is located on the second surface of the decoupling layer 513 including the second inductive layer 5132; the composition and/or thickness of the first inductive layer 5131 and the second inductive layer 5132 are different.

Optionally, the decoupling layer 513 includes a first induction layer 5131 and a second induction layer 5132, the first surface of the decoupling layer 513 is adjacent to the ferromagnetic layer 511, and the second surface of the decoupling layer 513 is adjacent to the ferromagnetic layer 512. Adjacent, the composition of the first inductive layer 5131 and the second inductive layer 5132 are different but the thicknesses are the same. In this way, the ferromagnetic layer 512 adjacent to the first inductive layer 5131 and the ferromagnetic layer adjacent to the second inductive layer can be made The magnitude of the magnetic anisotropy is different.

In the embodiment of the present application, the thickness of the first induction layer and the thickness of the second induction layer are both less than 2 nanometers.

The material of the first inductive layer and the material of the second inductive layer may include: any one of Mo, Ru, Rh, Pd, Hf, Ta, W, Ir, Pt, and Tb; or IrMn, FeMn, and PdMn. Any alloy; or any oxide of MgO and AlO _x ; or graphene material; or, other two-dimensional materials that are easily orbital hybridized with adjacent magnetic particles.

In the embodiments of the present application, the composition of the ferromagnetic layer includes mixed metal materials; the mixed metal materials include Co, Fe, Ni, Mn, Rh, Pd, Pt, Gd, Tb, Dy, Ho, B, Al, Si, Ga, At least two of Ge. By adjusting the composition and/or thickness of each ferromagnetic layer in the free layer 510, the magnitude of the magnetic anisotropy of each ferromagnetic layer is made different from each other. Please refer to FIG. 7 , which is a schematic structural diagram of a free layer provided by an embodiment of the present application.

Optionally, as shown in FIG. 7( a ), the ferromagnetic layer 511 and the ferromagnetic layer 512 have different compositions. Specifically, the ferromagnetic layer 511 may be Co ₂₀ Fe ₆₀ B ₂₀ , and the ferromagnetic layer 512 may be Co ₄₀ Fe ₄₀ B ₂₀ .

Optionally, as shown in FIG. 7( b ), the ferromagnetic layer 511 and the ferromagnetic layer 512 have the same composition but different thicknesses.

Optionally, as shown in FIGS. 7( c ) and ( d ), the composition and thickness of the ferromagnetic layer 511 and the ferromagnetic layer 512 are different.

The present application also provides a method for fabricating a magnetic memory device, comprising: depositing a buffer layer, a pinning layer, a reference layer and a barrier layer in sequence; depositing a free layer on the barrier layer; wherein the free layer includes at least two magnetic A ferromagnetic layer with variable moment direction and at least one decoupling layer, any two of the at least two ferromagnetic layers have different compositions and/or thicknesses; or, the free layer includes two or more decoupling layers , any two of the two or more decoupling layers have different thicknesses; the free layer is annealed; and a hard mask layer is deposited on the free layer.

In the embodiment of the present application, the deposition method may include physical vapor deposition and chemical vapor deposition, and specifically, may include magnetron sputtering, pulsed laser deposition, and molecular beam epitaxy.

In an optional embodiment of depositing a free layer on the barrier layer, the free layer may include a first ferromagnetic layer, a first decoupling layer and a second ferromagnetic layer, the first ferromagnetic layer and the second ferromagnetic layer The thickness and/or composition of the ferromagnetic layers are different; the above-mentioned first ferromagnetic layer, the above-mentioned first decoupling layer and the above-mentioned second ferromagnetic layer are sequentially deposited on the barrier layer. Specifically, the first ferromagnetic layer may be Co ₂₀ Fe ₆₀ B ₂₀ , the second ferromagnetic layer may be Co ₄₀ Fe ₄₀ B ₂₀ , and the thicknesses of the first ferromagnetic layer and the second ferromagnetic layer are the same, so that the The magnitudes of the magnetic anisotropy of the first ferromagnetic layer and the second ferromagnetic layer are different.

In another optional embodiment of depositing a free layer on the barrier layer, the free layer may include a first ferromagnetic layer, a first decoupling layer, a second ferromagnetic layer, a second decoupling layer and a third ferromagnetic layer Magnetic layer, the thickness and/or composition of the first decoupling layer and the second decoupling layer are different; the first ferromagnetic layer, the first decoupling layer, the second ferromagnetic layer are sequentially deposited on the barrier layer layer, the second decoupling layer described above, and the third ferromagnetic layer described above. Specifically, the thickness of the first decoupling layer is 7 nanometers, the thickness of the second decoupling layer is 6 nanometers, and the first decoupling layer includes a first induction layer, and the components of the first decoupling layer may include Al and Mo, the composition of the second decoupling layer may include Cr.

The present application also provides a method for fabricating a magnetic memory device, comprising: depositing a buffer layer, a pinning layer, a reference layer and a barrier layer in sequence; depositing a first ferromagnetic layer and a first decoupling layer on the barrier layer, annealing the first ferromagnetic layer and the first decoupling layer for the first time; depositing a second ferromagnetic layer on the first decoupling layer, and annealing the second ferromagnetic layer for the second time; wherein, the first annealing The annealing conditions are different from the annealing conditions of the second annealing, and the annealing conditions include annealing temperature, annealing time and annealing atmosphere; a hard mask layer is deposited on the second ferromagnetic layer.

It should be noted that the above-mentioned first ferromagnetic layer, the above-mentioned first decoupling layer and the above-mentioned second ferromagnetic layer are all free layers, and the free layer in this embodiment of the present application may further include more than two ferromagnetic layers and More than one decoupling layer. It is only different from the free layer structure in the examples of this application, but also by changing the technical means of annealing conditions, the interface quality (roughness, crystallinity, interface atomic diffusion degree, etc.) The technical effects of different sizes of the magnetic anisotropy of the magnetic layers all belong to the protection scope of the present application.

Specifically, the annealing temperature of the first annealing is higher than the annealing temperature of the second annealing, and the time required for the first annealing is greater than the time required for the second annealing. The gases introduced into different atmospheres may include H ₂ , Ar and mixed gases of H ₂ /Ar with different ratios.

In the embodiments of the present application, the direction of the magnetic moment of the ferromagnetic layer in the free layer is regulated by the Oersted magnetic field. Specifically, a solenoid or two long straight wires that are perpendicular to each other but not intersecting are arranged near the magnetic storage device, and voltage pulses of different amplitudes or polarities are passed through the solenoid or the two long straight wires to make the surrounding An Oersted magnetic field perpendicular to the surface of the film or parallel to the surface of the free layer is generated to control the magnetic memory device to exhibit different magnetic moment states.

Referring to FIG. 2 , the following description will be given by taking the example in FIG. 2( a ) that the free layer 510 includes two ferromagnetic layers 511 and 512 , and the ferromagnetic layers 511 and 512 have perpendicular magnetic anisotropy. A solenoid is arranged near the magnetic storage device to generate a vertical Oersted magnetic field, and the material of the solenoid can be Cu or Nb.

Please refer to FIG. 8 and FIG. 9. FIG. 8 is a schematic diagram of the relationship between the magnetic field direction of an Oersted magnetic field and a voltage pulse provided by an embodiment of the present application, and FIG. 9 is a magnetic moment of a magnetic storage device provided by an embodiment of the present application. Schematic diagram of state change with voltage pulse.

Assuming that the voltage pulse V is applied to the solenoid, an Oersted magnetic field Hp is generated. When V is positive, HP points from the lower side to the upper side, and when V is negative, Hp points from the upper side to the lower side; the magnetic moment of the reference layer 310 The direction is fixed as the direction from the lower side to the upper side, and is parallel to the free layer easy axis, indicated by the thick solid arrow M. During the t0 period, the magnetic memory device is initialized so that the direction of the magnetic moment M1 of the ferromagnetic layer 511 and the direction of the magnetic moment M2 of the ferromagnetic layer 512 are consistent with the direction of the magnetic moment M of the reference layer. 1"; during t1, when a small negative voltage pulse is applied to the solenoid, the M2 with a smaller magnetic anisotropy field begins to flip, and the M1 with a larger magnetic anisotropy field still points from the lower side to the upper side; during the t2 period, There is no current in the solenoid, M2 points from the upper side to the lower side, and M1 still points to the upper side from the lower side. At this time, it can indicate "magnetic moment state 2"; during t3, a large negative voltage pulse is applied to the solenoid coil, M1 begins to flip; during t4, there is no current in the solenoid, and both M1 and M2 point from the upper side to the lower side. At this time, it can represent "magnetic moment state 3"; during t5, a small positive voltage pulse is applied to the solenoid. , M2 with a smaller magnetic anisotropy field begins to flip; during t6, there is no current in the solenoid, M2 points from the lower side to the upper side, and M1 points from the upper side to the lower side. At this time, it can represent "magnetic moment state 4 ”; during t7, a larger positive voltage pulse is applied to the solenoid, and M1 with a larger anisotropic field begins to flip; during t8, there is no current in the solenoid, M1 and M2 point from the lower side to the upper side, at this time, May represent "Magnetic Moment State 1".

In the following, the free layer 510 in FIG. 2( b ) includes two ferromagnetic layers 511 and 512 , and the ferromagnetic layers 511 and 512 have in-plane magnetic anisotropy as an example for description. Two long straight wires are arranged around the magnetic storage device to generate parallel Oersted magnetic fields, the two wires are perpendicular to each other and are not connected, and there is a magnetic storage device near the intersection of the two wires.

Please refer to FIG. 10 and FIG. 11. FIG. 10 is a schematic diagram of the relationship between the magnetic field direction and voltage pulse of another Oersted magnetic field provided by the embodiment of the present application, and FIG. 11 is a schematic diagram of another magnetic storage device provided by the embodiment of the present application. Schematic representation of the state of magnetic moment as a function of voltage pulse.

Assume that a voltage pulse V1 is applied to wire 1 of the two wires to generate an Oersted magnetic field H1. When V1 is positive, H1 points from the lower side to the upper side; the wire 2 of the two wires applies a voltage pulse V2 to generate an Oersted magnetic field. The special magnetic field H2, when V2 is positive, H2 points from the left to the right, and only when there are voltage pulses on the two wires at the same time, it is possible to flip the magnetic moments of the ferromagnetic layers 511 and 512 in the magnetic memory device near the intersection Orientation; the magnetic moment M of the reference layer is parallel to the free layer easy axis and its orientation is fixed from left to right. During the t0 period, the magnetic memory device is initialized so that the direction of the magnetic moment M1 of the ferromagnetic layer 511 and the direction of the magnetic moment M2 of the ferromagnetic layer 512 are consistent with the direction of the magnetic moment M of the reference layer. 1"; during t1, a small positive voltage pulse is applied to wire 1, and a small negative voltage pulse is applied to wire 2, and M2 with a small magnetic anisotropy field begins to flip, while M1 only slightly deviates from the easy axis; period t2 , both conductor 1 and conductor 2 have no pulse voltage, M2 points from the right to the left, and M1 still returns to its nearest easy axis, and its direction points from the left to the right. At this time, it can indicate the "magnetic moment state" 2"; during t3, wire 1 applies a larger positive voltage pulse, while wire 2 applies a larger negative voltage pulse, M1 with a larger magnetic anisotropy field begins to flip, while M2 slightly deviates from the easy axis direction; t4 period , both conductor 1 and conductor 2 have no pulse voltage, M1 points from the right to the left, and M2 will eventually return to its easy axis, and the direction also points from the right to the left. At this time, it can indicate "magnetic moment state 3 ”; in t5 period, wire 1 applies a small positive voltage pulse, and wire 2 applies a small positive voltage pulse, M2 with a small magnetic anisotropy field begins to flip, and M1 only slightly deviates from the easy axis; t6 period , both conductor 1 and conductor 2 have no pulse voltage, M2 points from the left to the right, and M1 still returns to its nearest easy axis, and its direction points from the right to the left. At this time, it can represent the "magnetic moment state" 4"; during t7, wire 1 applies a larger positive voltage pulse, while wire 2 applies a larger positive voltage pulse, M1 with a larger magnetic anisotropy field begins to flip, while M2 only slightly deviates from the easy axis; t8 period , both conductor 1 and conductor 2 have no pulse voltage, M1 points from the left to the right, and M2 will eventually return to its easy axis, and the direction also points from the left to the right. At this time, it can indicate "magnetic moment state 1 ". It should be noted that the amplitude of the pulse voltage in the two wires can be adjusted according to the actual performance of the magnetic memory device. The amplitude is small.

The present application also provides a memory, including a wire for generating a magnetic field, the above-mentioned magnetic storage device and a magnetic detection device; a magnetic storage device for presenting various magnetic moment states according to the magnetic field generated by the wire; and a magnetic detection device for Obtain the magnetic moment state of a magnetic memory device.

In the embodiment of the present application, when writing data to the memory: the vertical or parallel Oersted magnetic field generated by the solenoid or two long straight wires that are perpendicular to each other and do not intersect with each other is used to control the magnetic moment state of the magnetic storage device so that it has Four or more magnetic moment states can represent multi-bit binary logic information.

When reading data from the memory: the magnetic moment state of the magnetic storage device is obtained through the magnetic detection device.

In this embodiment of the present application, the above-mentioned memory may be an MRAM. The MRAM includes a plurality of the above-mentioned magnetic storage devices. The magnetic storage device, the write bit line, the read bit line, the word line, the MOS transistor and the magnetic detection device together form the storage array of the MRAM. In this way, a large storage capacity can be realized, and the ultra-low storage capacity can be realized. MRAM working in the working temperature zone.

In the embodiments of the present application, the magnetic detection device may be a superconducting quantum interference device (SQUID) and a nano-superconducting quantum interference device (Nano-SQUID) based on a Josephson node or a nanobridge node. When the magnetic moment state of the magnetic storage device is obtained, a bias current is applied across the SQUID device to make the device work normally. When the magnetic moment state of the magnetic storage device changes, the magnetic flux passing through the SQUID device changes, and the SQUID device two The voltage at the terminals jumps, and the current state of the magnetic moment of the magnetic storage device can be obtained by measuring the voltage across the SQUID device.

In the following, the magnetic storage device in the memory will be described as having perpendicular magnetic anisotropy. Please refer to FIG. 12. FIG. 12 is a schematic structural diagram of a storage unit in a memory provided by an embodiment of the present application. The storage unit includes a magnetic storage device 1200, a SQUID device 1201, a solenoid 1202, a word line 1203, a word line 1204, a write /read bit line 1205, write/read bit line 1206, MOS1 and MOS2. The memory array of the memory includes a plurality of the above-mentioned memory cells. Wherein, the material of the write/read bit line 1205 and the write/read bit line 1206 may be Cu, Au, Al or other high conductivity metal materials, or may be Nb, NbN, NbTi, NbTiN, Nb3Sn, high temperature superconducting or other superconducting materials. The magnetic memory device 1200 includes a free layer 510, the free layer 510 includes two ferromagnetic layers, and the ferromagnetic layers have perpendicular magnetic anisotropy.

When writing data to the memory: according to the external address decoding circuit, energize the write/read bit line 1205, write/read bit line 1206 and word line 1203 corresponding to the storage address of the storage unit, at this time MOS1 is turned on, and the solenoid 1202 is energized Then, an Oersted magnetic field is generated, and by applying a voltage pulse to the solenoid 1202, the magnetic storage device 1200 can present different magnetic moment states according to the amplitude and positive and negative polarities of the voltage pulse, respectively representing different information.

When reading data from the memory: according to the external address decoding circuit, a bias current is applied to the word line 1204, the write/read bit line 1205 and the write/read bit line 1206 corresponding to the storage address of the memory cell, and the MOS2 is turned on at this time, By measuring the voltage across the SQUID device 1201, the current magnetic moment state of the magnetic storage device 1200 is obtained, that is, information corresponding to the current magnetic moment state is obtained. For example, "moment state 1", "moment state 2", "moment state 3", and "moment state 4" represent "00", "01", "10", and "11", respectively.

In the following, the magnetic storage device in the memory will be described as having in-plane magnetic anisotropy. Please refer to FIG. 13 . FIG. 13 is a schematic structural diagram of a memory cell in a memory provided by an embodiment of the present application. The memory cell includes a magnetic memory device 1300 , a SQUID device 1301 , a write bit line 1302 , a write bit line 1303 , and a word line 1304 , read bit line 1305, read bit line 1306 and MOS3. The write bit line 1302 and the write bit line 1303 are perpendicular to each other and do not cross each other for generating an Oersted magnetic field. The write bit line 1302, the write bit line 1303, the read bit line 1305 and the read bit line 1306 can be Cu, Au, Al or other high-conductivity metal materials, or can be Nb, NbN, NbTi, _NbTiN , Nb3Sn, High temperature superconducting or other superconducting materials.

When writing data to the memory: according to the external address decoding circuit, power on the write bit line 1302 and the write bit line 1303 corresponding to the storage address of the storage unit to generate an Oersted magnetic field. When a voltage pulse is applied, the magnetic memory device 1300 can present different magnetic moment states according to the amplitudes and positive and negative polarities of the two voltage pulses, respectively representing different information.

When reading data from the memory: according to the external address decoding circuit, the word line 1304, the read bit line 1305 and the read bit line 1306 corresponding to the storage address of the memory cell are powered on, the MOS3 is turned on, and the read bit line 1305 and the read bit line are turned on at the same time. 1306 applies a bias current, and obtains the current magnetic moment state of the magnetic storage device 1300 by measuring the voltage across the SQUID device 1301, that is, obtains information corresponding to the current magnetic moment state. For example, "moment state 1", "moment state 2", "moment state 3", and "moment state 4" represent "00", "01", "10", and "11", respectively.

The embodiments of the present application also provide a neural network system. Please refer to FIG. 14 . FIG. 14 is a schematic structural diagram of a neural network system provided by an embodiment of the present application, including a computing unit. The computing unit includes a magnetic storage device 1403 , a wire 1404 for generating an Oersted magnetic field, and a magnetic detection device 1405 and a resistive coupling element 1406; one end of the resistive coupling device 1406 is connected to one end of the magnetic detection device 1405, and the other end of the resistive coupling device 1406 is connected to the other end 1405 of the magnetic detection device; wherein, the magnetic storage device 1405 can be connected according to the wire The magnetic field generated by 1404 presents various magnetic moment states, and the synaptic weight of the neural network system corresponds to one of the various magnetic moment states; the magnetic detection device 1406 is used to obtain the magnetic moment state of the magnetic storage device 1405 to determine The synaptic weight corresponding to the magnetic moment state.

In the embodiments of the present application, the magnetic storage device is applied to the computing unit of the neural network system to simulate the synaptic behavior required in the learning and computing process of the human brain.

Assuming that there are four neurons A1, A2, A3, A4 at the input of the neural network system, and two neurons B1, B2 at the output, the input and output of the neural network satisfy the formula: B _j =σ(∑ _i A _i ·W _i,j ), where σ is a nonlinear equation; W is a synaptic weight; i is 1, 2, 3, or 4; and j is 1 or 2. In the embodiment of the present application, the magnetic memory device has four or more magnetic moment states, that is, for the same computing path, for example, the computing path from A1 to B1, there may be four or more synaptic weights. of various weight coefficients.

In this embodiment of the present application, the neural network system further includes four input wires 1401 and two output wires 1402. The four input wires 1401 are respectively connected to the input ports A1, A2, A3 and A4, and the two output wires 1402 are respectively connected to the output ports B1 and B2. One end of the magnetic detection device 1405 is connected to the input wire 1401, and the other end of the magnetic detection device 1405 is connected to the output wire 1402.

Specifically, the calculation process of the calculation unit of the above-mentioned neural network system includes:

The wire 1404 is energized, and the Oersted magnetic field generated by the wire 1404 is used to sequentially adjust or simultaneously control multiple magnetic storage devices 1403, so that all the magnetic storage devices 1404 are in a certain magnetic moment state, that is, there is a certain sudden change in the calculation of the entire neural network. touch weight;

When a calculation instruction is received, an analog voltage is applied to the four input wires 1401 as input data through a digital-to-analog converter, and a bias current is passed to the magnetic detection device 1405 at the same time; the input wire 1404, the magnetic detection device 1405, and the resistive coupling The element 1406 and the output wire 1402 form a loop to measure the current analog signal of the loop; the analog-to-digital converter converts the current analog signal into a digital signal and outputs the output wire 1402 to the peripheral circuit. Among them, by changing the magnetic moment state of the magnetic storage device 1404, the output voltage of the magnetic detection device 1405 can be changed. Under the condition that the amplitude and polarity of the voltage pulse on the input wire and the output wire remain unchanged, the measured value in the circuit The current analog signal will change; that is, the synaptic weight in the neural network calculation process changes with the change of the magnetic moment state of the magnetic storage device 1404. For the magnetic storage device 1404 with four or more magnetic moment states, it can represent Four or more synaptic weights, thus, various weight coefficients in the convolution calculation can be realized.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection of the present application. within the range.

Claims (9)

1. A magnetic memory device, comprising a free layer;

the free layer comprises at least two ferromagnetic layers with variable magnetic moment directions and at least one decoupling layer, and each decoupling layer in the at least one decoupling layer is arranged between two ferromagnetic layers in the at least two ferromagnetic layers; the thickness of the decoupling layer is more than or equal to 5 nanometers; a decoupling layer between the two ferromagnetic layers such that there is no coupling between the two ferromagnetic layers;

wherein any two of the ferromagnetic layers of the at least two ferromagnetic layers differ in composition and/or thickness; or, the free layer comprises more than two decoupling layers, and the thicknesses and/or compositions of any two decoupling layers in the more than two decoupling layers are different;

an decoupling layer of the at least one decoupling layer comprises a first inducing layer and/or a second inducing layer; wherein the first inducing layer is located at a first surface of an decoupling layer comprising the first inducing layer and the second inducing layer is located at a second surface of the decoupling layer comprising the second inducing layer; the first and second inducing layers are different in composition and/or thickness.

2. The magnetic memory device of claim 1,

the material of the decoupling layer comprises a metal material and/or an oxide material;

wherein the metal material comprises a metal material doped with impurity particles and a metal material doped without impurity particles.

3. The magnetic memory device of claim 2, wherein:

the metal material comprises any one of Al, Cr, Mn, Cu, Zn, Ag and Au;

the oxide material comprises MgO and Al₂O₃、AlO_x、BiFeO₃、NiO、CoO、Ni_0.5Co_0.5O、GdO_yAnd MgAl₂O₄Any one or more.

4. The magnetic memory device of claim 3, wherein the material of the first inducing layer and the material of the second inducing layer comprise:

any one metal of Mo, Ru, Rh, Pd, Hf, Ta, W, Ir, Pt and Tb; or;

any one alloy of IrMn, FeMn, PdMn; or;

MgO、AlO_xany one of the oxides; or;

a graphene material.

5. The magnetic memory device of claim 1,

the composition of the ferromagnetic layer comprises a mixed-metal material; the mixed metal material comprises at least two of Co, Fe, Ni, Mn, Rh, Pd, Pt, Gd, Tb, Dy, Ho, B, Al, Si, Ga and Ge.

6. A method of fabricating a magnetic memory device, comprising:

depositing a buffer layer, a pinning layer, a reference layer and a barrier layer in sequence;

depositing a free layer on the barrier layer; the free layer comprises at least two ferromagnetic layers with variable magnetic moment directions and at least one decoupling layer, and the compositions and/or thicknesses of any two ferromagnetic layers in the at least two ferromagnetic layers are different; or, the free layer comprises more than two decoupling layers, and the thicknesses and/or compositions of any two decoupling layers in the more than two decoupling layers are different; the thickness of the decoupling layer is more than or equal to 5 nanometers; a decoupling layer between the two ferromagnetic layers such that there is no coupling between the two ferromagnetic layers; an decoupling layer of the at least one decoupling layer comprises a first inducing layer and/or a second inducing layer; wherein the first inducing layer is located at a first surface of an decoupling layer comprising the first inducing layer and the second inducing layer is located at a second surface of the decoupling layer comprising the second inducing layer; the first and second inducing layers are different in composition and/or thickness;

annealing the free layer;

And depositing a hard mask layer on the free layer.

7. A method of fabricating a magnetic memory device, comprising:

depositing a buffer layer, a pinning layer, a reference layer and a barrier layer in sequence;

depositing a first ferromagnetic layer and a first decoupling layer on the barrier layer, and annealing the first ferromagnetic layer and the first decoupling layer for a first time;

depositing a second ferromagnetic layer on the first decoupling layer, and annealing the second ferromagnetic layer a second time; wherein the annealing conditions of the first annealing and the annealing conditions of the second annealing are different, and the annealing conditions comprise annealing temperature, annealing time and annealing atmosphere; the thickness of the first decoupling layer is more than or equal to 5 nanometers; the first decoupling layer is such that there is no coupling between the first ferromagnetic layer and the second ferromagnetic layer;

a hard mask layer is deposited on the second ferromagnetic layer.

8. A memory comprising conductive lines for generating a magnetic field, magnetic storage means and magnetic detection means;

the magnetic memory device includes a free layer; the free layer comprises at least two ferromagnetic layers with variable magnetic moment directions and at least one decoupling layer, and each decoupling layer in the at least one decoupling layer is arranged between two ferromagnetic layers in the at least two ferromagnetic layers; the thickness of the decoupling layer is more than or equal to 5 nanometers; a decoupling layer between the two ferromagnetic layers such that there is no coupling between the two ferromagnetic layers; wherein any two of the ferromagnetic layers of the at least two ferromagnetic layers differ in composition and/or thickness; or, the free layer comprises more than two decoupling layers, and the thicknesses and/or compositions of any two decoupling layers in the more than two decoupling layers are different; an decoupling layer of the at least one decoupling layer comprises a first inducing layer and/or a second inducing layer; wherein the first inducing layer is located at a first surface of an decoupling layer comprising the first inducing layer and the second inducing layer is located at a second surface of the decoupling layer comprising the second inducing layer; the first and second inducing layers are different in composition and/or thickness;

The magnetic storage device is used for presenting a plurality of magnetic moment states according to the magnetic field generated by the wire;

the magnetic detection device is used for acquiring the magnetic moment state of the magnetic storage device.

9. A neural network system, comprising a computing unit; the computing unit comprises a lead wire for generating a magnetic field, a magnetic storage device, a magnetic detection device and a resistance type coupling device;

one end of the resistive coupling device is connected with one end of the magnetic detection device, and the other end of the resistive coupling device is connected with the other end of the magnetic detection device;

the magnetic memory device includes a free layer; the free layer comprises at least two ferromagnetic layers with variable magnetic moment directions and at least one decoupling layer, and each decoupling layer in the at least one decoupling layer is arranged between two ferromagnetic layers in the at least two ferromagnetic layers; the thickness of the decoupling layer is more than or equal to 5 nanometers; a decoupling layer between the two ferromagnetic layers such that there is no coupling between the two ferromagnetic layers; wherein any two of the ferromagnetic layers of the at least two ferromagnetic layers differ in composition and/or thickness; or, the free layer comprises more than two decoupling layers, and the thicknesses and/or compositions of any two decoupling layers in the more than two decoupling layers are different; an decoupling layer of the at least one decoupling layer comprises a first inducing layer and/or a second inducing layer; wherein the first inducing layer is located at a first surface of an decoupling layer comprising the first inducing layer and the second inducing layer is located at a second surface of the decoupling layer comprising the second inducing layer; the first and second inducing layers are different in composition and/or thickness;

Wherein the magnetic storage device is capable of assuming a plurality of magnetic moment states according to a magnetic field generated by the wire, and a synaptic weight of the neural network system corresponds to one of the plurality of magnetic moment states;

the magnetic detection device is used for acquiring the magnetic moment state of the magnetic storage device so as to determine the synaptic weight corresponding to the magnetic moment state.

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