阅读说明：本技术 一种自旋轨道转矩磁阻式随机存储器及其制造方法 (Spin orbit torque magnetic resistance type random access memory and manufacturing method thereof ) 是由 杨美音 罗军 崔岩 许静 于 2021-08-25 设计创作，主要内容包括：本申请提供了一种自旋轨道转矩磁阻式随机存储器及其制造方法,包括：铁电薄膜层,设置有两个金属电极,通过两个金属电极向铁电薄膜层施加第一电压；底电极,位于铁电薄膜层之上并设置于铁电薄膜层中部,呈长条形,在底电极两端施加第二电压；隧道结,位于底电极之上并设置于底电极中部；其中,两个金属电极相对设置在铁电薄膜层相对的两个边缘上,且两个边缘位于底电极长边方向的两侧,通过两个金属电极施加第一电压的方向与底电极短边方向平行；通过第一电压与第二电压的正负,控制磁化的定向翻转。从而在实现磁矩定向翻转的同时,利于器件的集成和产业化。(The application provides a spin-orbit torque magnetoresistive random access memory and a method of manufacturing the same, comprising: a ferroelectric thin film layer provided with two metal electrodes through which a first voltage is applied to the ferroelectric thin film layer; the bottom electrode is positioned on the ferroelectric thin film layer, arranged in the middle of the ferroelectric thin film layer and in a strip shape, and a second voltage is applied to two ends of the bottom electrode; the tunnel junction is positioned above the bottom electrode and arranged in the middle of the bottom electrode; the two metal electrodes are oppositely arranged on two opposite edges of the ferroelectric thin film layer, the two edges are positioned on two sides of the long edge direction of the bottom electrode, and the direction of applying the first voltage through the two metal electrodes is parallel to the short edge direction of the bottom electrode; and controlling the orientation reversal of magnetization through the positive and negative of the first voltage and the second voltage. Therefore, the directional overturning of the magnetic moment is realized, and the integration and industrialization of the device are facilitated.)

1. A spin-orbit torque magnetoresistive random access memory, comprising:

a ferroelectric thin film layer provided with two metal electrodes through which a first voltage is applied to the ferroelectric thin film layer;

the bottom electrode is positioned on the ferroelectric thin film layer, arranged in the middle of the ferroelectric thin film layer and in a strip shape, and a second voltage is applied to two ends of the bottom electrode;

the tunnel junction is positioned above the bottom electrode and arranged in the middle of the bottom electrode;

the two metal electrodes are oppositely arranged on two opposite edges of the ferroelectric thin film layer, the two edges are positioned on two sides of the long side direction of the bottom electrode, and the direction of applying a first voltage through the two metal electrodes is parallel to the short side direction of the bottom electrode; and controlling the orientation reversal of magnetization through the positive and negative of the first voltage and the second voltage.

2. The memory according to claim 1, wherein the ferroelectric thin film layer is made of HfZrO or PZT and has a thickness of 3-10 nm.

3. The memory according to claim 1, wherein the metal electrode material is Al, Cu or W, and has a thickness of 100-400 nm.

4. The memory according to claim 1, wherein the first voltage and the second voltage are in a range of-2 to 2V.

5. The memory according to claim 1, wherein the tunnel junction comprises a free layer, a tunneling layer and a reference layer which are sequentially stacked from bottom to top, wherein the free layer is connected with the bottom electrode.

6. The memory of claim 1, wherein the tunnel junction is circular, elliptical, or rectangular.

7. A method of manufacturing a spin-orbit torque magnetoresistive random access memory, comprising:

growing a ferroelectric film on the circuit board to form a ferroelectric film layer;

growing a bottom electrode on the ferroelectric film layer, wherein the bottom electrode is in a strip shape;

depositing metal electrodes on two edges of the ferroelectric thin film layer on two sides of the long side direction of the bottom electrode;

and forming a tunnel junction in the middle on the bottom electrode.

8. The method according to claim 7, wherein a tunnel junction is formed in the middle on the bottom electrode, in particular:

growing a free layer, a tunneling layer and a reference layer on the bottom electrode in sequence;

and carrying out ion beam etching on the free layer, the tunneling layer and the reference layer to form a tunnel junction.

9. The method according to claim 7, wherein the ferroelectric thin film layer is made of HfZrO or PZT and has a thickness of 3-10 nm.

10. The method of claim 8, wherein a pinning layer is also grown on the reference layer of the tunnel junction for solidifying the magnetization direction.

Technical Field

The present disclosure relates to semiconductor devices and manufacturing methods thereof, and more particularly, to a spin-orbit torque magnetoresistive random access memory and a manufacturing method thereof.

Background

With the development of memory technology and electronic technology, random access memories are widely used, and can be independent or integrated in devices using random access memories, such as processors, application specific integrated circuits or systems on a chip.

Spin-orbit torque Magnetoresistive Random Access Memory (SOT-MRAM) is a magnetic Random Access Memory for Random storage by using magnetic moment reversal, and has the advantages of high-speed read-write capability, high integration level and infinite repeated writing, and has extremely high durability because the writing current does not pass through a tunneling junction, and is suitable for being applied to a storage and calculation integrated device. In the device, Spin-Orbit coupling (SOT) can be utilized to generate Spin current and induce the magnetic moment of a ferromagnet to turn, but the turning direction of the magnetic moment is random under the action of the current, an external magnetic field is needed to realize the directional turning of the magnetic moment, and the external magnetic field is not beneficial to the integration of the device.

Disclosure of Invention

In order to solve the technical problems, the application provides a spin orbit torque magnetoresistive random access memory and a manufacturing method thereof, which are beneficial to integration and industrialization of devices while realizing directional overturning of magnetic moments.

In a first aspect, the present application provides a spin-orbit torque magnetoresistive random access memory comprising:

a ferroelectric thin film layer provided with two metal electrodes through which a first voltage is applied to the ferroelectric thin film layer;

the bottom electrode is positioned on the ferroelectric thin film layer, arranged in the middle of the ferroelectric thin film layer and in a strip shape, and a second voltage is applied to two ends of the bottom electrode;

the tunnel junction is positioned above the bottom electrode and arranged in the middle of the bottom electrode;

the two metal electrodes are oppositely arranged on two opposite edges of the ferroelectric thin film layer, the two edges are positioned on two sides of the long side direction of the bottom electrode, and the direction of applying a first voltage through the two metal electrodes is parallel to the short side direction of the bottom electrode; and controlling the orientation reversal of magnetization through the positive and negative of the first voltage and the second voltage.

Optionally, the ferroelectric thin film layer is made of HfZrO or PZT, and the thickness of the ferroelectric thin film layer is 3-10 nm.

Optionally, the metal electrode material is Al, Cu or W, and the thickness is 100-400 nm.

Optionally, the first voltage and the second voltage range from-2V to 2V.

Optionally, the tunnel junction includes a free layer, a tunneling layer, and a reference layer sequentially stacked from bottom to top, where the free layer is connected to the bottom electrode.

Optionally, the tunnel junction is circular, elliptical or rectangular.

In a second aspect, the present application provides a method of manufacturing a spin-orbit torque magnetoresistive random access memory, comprising:

growing a ferroelectric film on the circuit board to form a ferroelectric film layer;

growing a bottom electrode on the ferroelectric film layer, wherein the bottom electrode is in a strip shape;

depositing metal electrodes on two edges of the ferroelectric thin film layer on two sides of the long side direction of the bottom electrode;

and forming a tunnel junction in the middle on the bottom electrode.

Optionally, a tunnel junction is formed in the middle of the bottom electrode, specifically:

growing a free layer, a tunneling layer and a reference layer on the bottom electrode in sequence;

and carrying out ion beam etching on the free layer, the tunneling layer and the reference layer to form a tunnel junction.

Optionally, the ferroelectric thin film layer is made of HfZrO or PZT, and the thickness of the ferroelectric thin film layer is 3-10 nm.

Optionally, a pinning layer is also grown on the reference layer of the tunnel junction for solidifying the magnetization direction.

Compared with the prior art, the method has the advantages that:

the application provides a spin-orbit torque magnetoresistive random access memory and a method of manufacturing the same, comprising: the ferroelectric thin film layer is provided with two metal electrodes, a first voltage is applied to the ferroelectric thin film layer through the two metal electrodes to realize local polarization of the ferroelectric thin film layer, and the local polarization causes the ferroelectric thin film layer to generate a stress gradient, so that local deformation of the ferroelectric thin film layer is realized, further the deformation on the ferroelectric thin film is non-uniform, the bottom electrode is positioned on the ferroelectric thin film layer, is arranged in the middle of the ferroelectric thin film layer and is in a strip shape, and a second voltage is applied to two ends of the bottom electrode; the bottom electrode is affected by the deformation unevenness to generate the uneven spin orbit coupling effect, the bottom electrode spin Hall effect can be regulated and controlled, so that a spin current gradient is formed on the bottom electrode, and a tunnel junction is positioned on the bottom electrode and arranged in the middle of the bottom electrode; the two metal electrodes are oppositely arranged on two opposite edges of the ferroelectric thin film layer, the two edges are positioned on two sides of the long edge direction of the bottom electrode, and the direction of applying the first voltage through the two metal electrodes is parallel to the short edge direction of the bottom electrode; the directional magnetization reversal of the free layer is realized through the positive and negative of the first voltage and the second voltage, so that the stored data "0" or "1" can be written into the SOT-MRAM by controlling the directional magnetization reversal of the free layer in the tunnel junction through the current, so that the magnetization directions of the free layer and the reference layer are the same or opposite, and the data storage is completed. In addition, the magnetization reversal is realized by adding the ferroelectric film, which is beneficial to realizing the integration and industrialization of the SOT-MRAM device.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic diagram illustrating a top view structure of a spin-orbit torque magnetoresistive random access memory according to an embodiment of the present disclosure;

FIG. 2 is a schematic cross-sectional view along AA in FIG. 1;

fig. 3 is a flowchart illustrating a method for manufacturing a spin-orbit torque magnetoresistive random access memory according to an embodiment of the present application.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, but the present application may be practiced in other ways than those described herein, and it will be apparent to those of ordinary skill in the art that the present application is not limited by the specific embodiments disclosed below.

Example 1

In one embodiment of the present invention, a spin-orbit torque magnetoresistive random access memory is disclosed, which is schematically illustrated in fig. 1 in a top view and fig. 2 in a cross-sectional view, and comprises:

and a ferroelectric thin film layer provided with two metal electrodes through which a first voltage is applied to the ferroelectric thin film layer.

The bottom electrode is positioned on the ferroelectric thin film layer, arranged in the middle of the ferroelectric thin film layer and in a strip shape, and a second voltage is applied to two ends of the bottom electrode;

and the tunnel junction is positioned on the bottom electrode, arranged in the middle of the bottom electrode and comprises a free layer, a tunneling layer and a reference layer which are sequentially stacked from bottom to top.

The two metal electrodes are oppositely arranged on two opposite edges of the ferroelectric thin film layer, the two edges are positioned on two sides of the long side direction of the bottom electrode, and the direction of applying a first voltage through the two metal electrodes is parallel to the short side direction of the bottom electrode; and controlling the orientation reversal of magnetization through the positive and negative of the first voltage and the second voltage.

Compared with the prior art, the ferroelectric thin film layer is arranged below the bottom electrode, the two metal electrodes are arranged, the first voltage is applied to the ferroelectric thin film layer through the two metal electrodes to realize local polarization of the ferroelectric thin film layer, the local polarization causes the ferroelectric thin film layer to generate a stress gradient, so that the local deformation of the ferroelectric thin film layer is realized, the deformation of the ferroelectric thin film layer is further enabled to be non-uniform, the bottom electrode is positioned on the ferroelectric thin film layer and arranged in the middle of the ferroelectric thin film layer and is in a strip shape, and the second voltage is applied to two ends of the bottom electrode; the bottom electrode is affected by the deformation unevenness to generate the uneven spin orbit coupling effect, the bottom electrode spin Hall effect can be regulated and controlled, so that a spin current gradient is formed on the bottom electrode, and a tunnel junction is positioned on the bottom electrode and arranged in the middle of the bottom electrode; the two metal electrodes are oppositely arranged on two opposite edges of the ferroelectric thin film layer, the two edges are positioned on two sides of the long edge direction of the bottom electrode, and the direction of applying the first voltage through the two metal electrodes is parallel to the short edge direction of the bottom electrode; the directional magnetization reversal of the free layer is realized through the positive and negative of the first voltage and the second voltage, so that the stored data "0" or "1" can be written into the SOT-MRAM by controlling the directional magnetization reversal of the free layer in the tunnel junction through the current, so that the magnetization directions of the free layer and the reference layer are the same or opposite, and the data storage is completed. In addition, the magnetization reversal is realized by adding the ferroelectric film, which is beneficial to realizing the integration and industrialization of the SOT-MRAM device.

In the implementation, the ferroelectric material adopted by the ferroelectric thin film layer can be HfZrO or PZT; preferably HfZrO, compatible with CMOS processes, facilitating device integration. The thickness of the ferroelectric thin film layer is 3-10nm, preferably 3nm, and the control voltage of the ferroelectric thin film layer can be reduced.

Specifically, the ferroelectric thin film layer is arranged in a square shape, and the bottom electrode partially covers the ferroelectric thin film layer. It is understood that the bottom electrode is smaller than the ferroelectric thin film layer, i.e., the bottom area of the bottom electrode is smaller than the upper surface area of the ferroelectric thin film layer. The ferroelectric film layer is set to be square, so that the miniaturization development of the device is facilitated, and the subsequent integration and industrialization are facilitated.

When the ferroelectric thin film is implemented, the metal electrode can be made of Al, Cu and W, the thickness can be 100-400 nm, the ferroelectric thin film can be interconnected with the metal thin film, and the ferroelectric thin film can generate better local deformation after voltage is applied; more specifically, the metal electrode may be provided in a rectangular structure. It is understood that the metal electrode is disposed at an edge portion of the ferroelectric thin film layer, and may be partially connected to the ferroelectric thin film layer for applying a voltage to the ferroelectric thin film layer.

Specifically, the lengths of the two metal electrodes are equal to the length of the edge of the ferroelectric thin film layer. It should be noted that the length of the two metal electrodes is equal to the length of the edge of the ferroelectric thin film layer, so that the gradient of the stress generated by the ferroelectric thin film layer is larger, and the effect of increasing the spin current gradient is achieved.

In the implementation, the range of the first voltage and the second voltage is-2V. It should be noted that the specific values of the first voltage and the second voltage can be selected and determined according to the requirements of the practical application.

In specific implementation, the bottom electrode may be a metal layer or a topological insulating layer having a spin coupling effect, and further, may be made of a material having a strong spin orbit coupling effect, and may be made of a metal material such as Ta, Pt, Hf, Ir, and CuIr, or a topological insulator material such as BiSn and BiSe, or a metal oxide material such as SrRuO 3. Furthermore, the thickness of the bottom electrode can be selected from 0 to 20 nm.

It can be understood that the bottom electrode is used for providing spin orbit torque, current is introduced into the bottom electrode, electrons with upward spin and electrons with downward spin in the bottom electrode are gathered at two sides of the bottom electrode, the strong spin coupling effect generated by the bottom electrode generates spin current, and the spin current is utilized to realize the magnetic direction inversion of the free layer in the tunnel junction.

In implementation, the tunnel junction comprises a free layer, a tunneling layer and a reference layer which are sequentially stacked from bottom to top, wherein the free layer is connected with the bottom electrode; the free layer and the reference layer are magnetic layers, vertical anisotropy is formed between the free layer and the reference layer, and the tunneling layer is a nonmagnetic layer.

In implementation, the tunnel junction is circular, elliptical or rectangular; preferably, the tunnel junction is cylindrical and is vertically disposed on the bottom electrode.

It will be appreciated that the tunnel junction magnetization is oriented perpendicular to the short side of the bottom electrode, i.e., the direction of the applied current. The magnetization direction of the free layer in the tunnel junction can be changed and is used for writing and storing data, the magnetization direction in the reference layer is fixed, the bottom electrode generates a spin current perpendicular to the current direction after being electrified, and when the spin current flows through the free layer, the magnetization direction of the free layer can be induced to be reversed, so that the magnetization directions of the free layer and the reference layer are the same or opposite, and the writing and the storing of the data are realized. When the directions of the free layer and the reference layer are the same, the tunnel junction is in a low-resistance state and is used for representing low level 0; when the directions of the free layer and the reference layer are opposite, the tunnel junction presents a high resistance state for representing a low level "1".

Specifically, the free layer and the reference layer are made of ferromagnetic materials with perpendicular anisotropy, single ferromagnetic materials, alloy ferromagnetic materials or metal oxides with magnetism can be selected, and in addition, the free layer and the reference layer can be made of the same material or different materials. The tunneling layer is made of nonmagnetic metal or insulating material, and nonmagnetic metal such as Cu or Ag can be selected, and insulating material such as aluminum oxide or magnesium oxide can also be selected.

More specifically, the thicknesses of the free layer and the reference layer can be selected from 0-3 nm; the thickness of the tunneling layer can be selected from 0-2 nm.

Furthermore, the free layer and the reference layer can adopt a multilayer film structure, and a cobalt-platinum multilayer film or a cobalt-nickel multilayer film can be adopted, so that the free layer and the reference layer have better perpendicular magnetic anisotropy.

It should be noted that the tunnel junction is cylindrical, and the diameter of the bottom surface of the tunnel junction is smaller than or equal to the length of the short side of the bottom electrode, so as to reduce the manufacturing cost, facilitate the miniaturization of the size, and be more suitable for memories with different structures. Furthermore, an output terminal is connected to the reference layer.

In particular implementations, the tunnel junction may also have a pinning layer above the reference layer for solidifying the magnetization direction, and IrMn or CoPt may be used. The tunnel junction may be further provided with a protective layer on the uppermost layer for protecting the tunnel junction from damage, and Ta or Ru may be used.

Example 2

One embodiment 2 of the present invention discloses a method for manufacturing a spin-orbit torque magnetoresistive random access memory, as shown in fig. 3, including:

and S1, growing a ferroelectric film on the circuit board to form a ferroelectric film layer.

In the implementation process, the ferroelectric thin film layer is made of HfZrO or PZT, and the thickness of the ferroelectric thin film layer is 3-10 nm.

Specifically, the growth mode of the ferroelectric thin film is one of physical vapor deposition and atomic layer deposition.

More specifically, Physical Vapor Deposition (PVD) and Atomic Layer Deposition (ALD) may be used to grow a ferroelectric thin film, such as a zro, compatible with a Complementary Metal-Oxide-Semiconductor (CMOS) thin film, on a circuit board.

Specifically, the ferroelectric thin film layer is processed into a square shape, the bottom electrode is located in the middle of the ferroelectric thin film layer, and the processing mode comprises ion beam etching and reactive ion etching. It can be understood that the ferroelectric thin film layer is arranged in a square shape, which is beneficial to the miniaturization development of the device and is also convenient for the subsequent integration and industrialization.

And S2, growing a bottom electrode on the ferroelectric film layer, wherein the bottom electrode is in a strip shape.

Specifically, a bottom electrode can be formed by growing a topological insulator material such as BiSn or SnTe on the ferroelectric thin film layer by adopting molecular beam epitaxial growth or a magnetron sputtering method, and the thickness of the bottom electrode can be 3-10 nm. It can be understood that the current is introduced into the bottom electrode, and the spin current is generated due to the strong spin orbit coupling effect, so that the magnetic direction of the magnetic free layer is turned over by the spin current.

And S3, depositing metal electrodes on two edges of the ferroelectric thin film layer on two sides of the bottom electrode in the long side direction.

Specifically, the metal electrode can be etched into a rectangular structure by ion beam etching.

In practice, the length of the two metal electrodes is equal to the length of the edge of the ferroelectric film layer. It should be noted that the length of the two metal electrodes is equal to the length of the edge of the ferroelectric thin film layer, so that the gradient of the stress generated by the ferroelectric thin film layer is larger, and the effect of increasing the spin current gradient is achieved.

And S4, forming a tunnel junction in the middle on the bottom electrode.

In implementation, the tunnel junction is formed in the middle of the bottom electrode, specifically:

growing a free layer, a tunneling layer and a reference layer on the bottom electrode in sequence;

and carrying out ion beam etching on the free layer, the tunneling layer and the reference layer to form a tunnel junction.

Specifically, a magnetic free layer, a nonmagnetic tunneling layer, and a magnetic reference layer may be sequentially grown on the bottom electrode by sputtering. More specifically, the free layer, the tunneling layer and the reference layer are processed into a cylindrical shape, so that the tunnel junction is cylindrical and perpendicular to the bottom electrode, and the output end is connected to the reference layer.

In practice, a pinning layer may also be grown on the reference layer of the tunnel junction for solidifying the magnetization direction; further, a protective layer may be grown on the uppermost layer to protect the tunnel junction from damage.

Example 3

An embodiment 3 of the present invention provides a writing method for a spin-orbit torque magnetoresistive random access memory, which can perform corresponding information storage according to the spin-orbit torque magnetoresistive random access memory in embodiment 1, and specifically includes:

and inputting a first voltage to the ferroelectric film layer through the two metal electrodes, inputting a second voltage to the bottom electrode layer through two ends of the bottom electrode, and controlling the positive and negative of the first voltage and the second voltage to complete the writing of the SOT-MRAM. That is, in the SOT-MRAM writing, when the first voltage applied to the ferroelectric thin film layer is positive or negative, different data can be written by changing the positive or negative of the second voltage applied to the bottom electrode; different data can also be written by changing the positive or negative of the first voltage applied to the ferroelectric thin film layer when the positive or negative of the second voltage applied to the bottom electrode is determined.

Specifically, the range of the first voltage and the second voltage is-2V. It should be noted that the specific values of the first voltage and the second voltage can be selected and determined according to the requirements of the practical application.

Exemplarily, as shown in fig. 1, two metal electrodes of the SOT-MRAM in the present embodiment are disposed on both sides, that is, in the longitudinal direction of the bottom electrode, with metal electrode V3 as a positive electrode and metal electrode V4 as a negative electrode, and a first voltage is applied across metal electrode V3 and metal electrode V4; and taking the left end of the bottom electrode as a positive electrode, taking the right end of the bottom electrode as a negative electrode, and applying a second voltage to the two ends of the bottom electrode.

Specifically, when no voltage is applied to the ferroelectric layer, the bottom electrode is applied with a voltage that does not cause the magnetic moment to flip its orientation, i.e. the written data is "0" or "1" randomly. After applying a voltage to the ferroelectric layer, writing data "0" or "1" by changing the positive and negative of the voltage applied to the ferroelectric layer and the voltage applied to the bottom electrode, specifically:

when the first voltage is positive voltage and the second voltage is positive voltage, positive current is conducted from the left end to the right end of the bottom electrode, so that the magnetic moment of the free layer of the tunnel junction is reversed, the direction of the magnetic moment of the free layer is opposite to that of the magnetic moment of the reference layer, the resistance of the magnetic tunnel junction is in a high resistance state, and the written data is 1.

When the first voltage is negative voltage, the second voltage is positive voltage, namely, positive current is conducted from the left end to the right end of the bottom electrode, so that the magnetic moment of the free layer of the tunnel junction is reversed, the direction of the magnetic moment of the free layer is the same as that of the magnetic moment of the reference layer, the resistance of the magnetic tunnel junction is in a high resistance state, and the written data is '0'.

When the first voltage is positive voltage, negative current is conducted to the second voltage, namely, the left end to the right end of the bottom electrode, so that the magnetic moment of the free layer of the tunnel junction is reversed, the direction of the magnetic moment of the free layer is the same as that of the magnetic moment of the reference layer, the resistance of the magnetic tunnel junction is in a low resistance state, and the written data is '0'.

When the first voltage is negative voltage, negative current is conducted to the second voltage, namely, the left end to the right end of the bottom electrode, so that the magnetic moment of the free layer of the tunnel junction is reversed, the direction of the magnetic moment of the free layer is opposite to that of the magnetic moment of the reference layer, the resistance of the magnetic tunnel junction is in a high resistance state, and the written data is 1.

In summary, by controlling the positive and negative of the first voltage and the second voltage, i.e. by controlling the direction of the applied voltage of the ferroelectric thin film layer and the bottom electrode, the directional writing of the SOT-MRAM is realized.

Those skilled in the art will appreciate that all or part of the flow of the method implementing the above embodiments may be implemented by a computer program, which is stored in a computer readable storage medium, to instruct related hardware. The computer readable storage medium is a magnetic disk, an optical disk, a read-only memory or a random access memory.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments.

The foregoing is merely a preferred embodiment of the present application and, although the present application discloses the foregoing preferred embodiments, the present application is not limited thereto. Those skilled in the art can now make numerous possible variations and modifications to the disclosed embodiments, or modify equivalent embodiments, using the methods and techniques disclosed above, without departing from the scope of the claimed embodiments. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application still fall within the protection scope of the technical solution of the present application without departing from the content of the technical solution of the present application.