WO2022206619A1

WO2022206619A1 - Phase change material suitable for phase change memory and phase change memory

Info

Publication number: WO2022206619A1
Application number: PCT/CN2022/083150
Authority: WO
Inventors: 马平; 李响; 陈鑫
Original assignee: 华为技术有限公司
Priority date: 2021-04-02
Filing date: 2022-03-25
Publication date: 2022-10-06
Also published as: CN113140674A

Abstract

The embodiments of the present application provide a phase change material suitable for a phase change memory and a phase change memory. The phase change material comprises: a phase change layer and a superlattice interlayer. The phase change layer and the superlattice interlayer form a superlattice structure, and the phase change layer comprises antimony atoms Sb. Compared to phase change materials which generally contain antimony atoms, the superlattice provided in the embodiments of the present application has a larger viscosity, better application reliability and longer service life.

Description

Phase change material and phase change memory suitable for phase change memory

This application claims the priority of the Chinese patent application filed on April 2, 2021 with the State Intellectual Property Office of China, the application number is 202110363018.8, and the invention name is "phase change material suitable for phase change memory and phase change memory", all of which are The contents are incorporated herein by reference.

technical field

The present application relates to the field of phase change memory materials, and in particular, to a phase change material suitable for a phase change memory and a phase change memory.

Background technique

A phase change memory (phase change memory, PCM) is composed of a first electrode, a phase change material and a second electrode, wherein the first electrode and the second electrode are connected through the phase change material. The states of phase change materials include crystalline state and amorphous state. In the amorphous state, the phase change material has a short-distance atomic energy level and a low free electron density, which makes it have a high resistivity. In the crystalline state, phase-change materials have long-distance atomic energy levels and high free electron density, resulting in low resistivity. The phase change memory can store data by using the resistivity difference shown by the phase change material inside it when it transforms between the crystalline state and the amorphous state.

Due to the relatively fast phase change speed of antimony atom Sb in the crystallization process, phase change materials containing antimony atoms are mostly used in phase change materials at present. However, the materials containing antimony atoms are prone to atomic migration, resulting in a decrease in the viscosity of the prepared phase change materials. , poor application reliability and service life.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the prior art, the embodiments of the present application show a phase change material and a phase change memory.

In a first aspect, embodiments of the present application provide a phase change material, the phase change material includes: a phase change layer and a superlattice interlayer; the phase change layer and the superlattice interlayer form a superlattice structure, and the phase The change layer includes antimony atoms Sb; the superlattice interlayer is in a crystalline state when the phase change layer is switched between a crystalline state and an amorphous state.

In this implementation manner, compared with phase change materials generally containing antimony atoms, the phase change materials provided in the embodiments of the present application have larger viscosity, better application reliability and longer service life. Since the superlattice interlayer remains in the crystalline state in the process of converting the phase change layer to the crystalline state, and there is no migration of molecules, atoms or ions in the superlattice interlayer, the superlattice interlayer acts to limit the antimony atoms in the phase change layer. Due to the effect of migration, antimony atoms can only migrate in the phase change layer, thus reducing the number of voids caused by the migration of antimony atoms to a certain extent, which improves the viscosity of the phase change material, and improves the application reliability of the phase change material. The service life has been improved; the antimony atoms in the phase change layer are converted from crystalline state to amorphous state; there is no migration of molecules, atoms or ions in the superlattice interlayer, and the superlattice interlayer acts to limit the antimony atoms in the phase change layer Due to the migration of antimony atoms, the antimony atoms can only migrate in the phase change layer, so to a certain extent, the number of voids generated by the migration of antimony atoms is reduced, so that the viscosity of the phase change material is improved, and the application reliability of the phase change material is improved. and service life are improved.

With reference to the first aspect, in a first possible implementation manner of the first aspect, the superlattice interlayers and the phase change layers are alternately arranged, and multiple layers are formed between the superlattice interlayers and the phase change layers. An interface, where the superlattice interlayer provides a nucleus for the phase change layer at the location of the interface when the phase change layer is transformed into a crystalline state.

In this implementation manner, the superlattice interlayer and the phase change layer are alternately arranged, and a plurality of interfaces are formed between the superlattice interlayer and the phase change layer, and the phase change layer is transformed into a crystal state. When , the superlattice interlayer provides nucleus points for the phase change layer at the position of the interface, thereby increasing the number of nucleus points in the phase change material, and the increase in the number of nucleus points can shorten the crystallization of the phase change layer time, the crystallization time of the corresponding phase change material is shortened, so that the phase change material can realize ultra-fast read and write operations.

With reference to the first aspect, in a second possible implementation manner of the first aspect, the difference between the first lattice constant and the second lattice parameter is less than or equal to a lattice parameter threshold, and the first lattice constant is the The lattice constant of the superlattice interlayer, and the second lattice constant is the lattice constant of the phase change layer.

In this implementation manner, the difference between the first lattice constant and the second lattice parameter is less than or equal to the lattice parameter threshold, the superlattice interlayer and the phase change layer have a good degree of lattice matching, and the superlattice interlayer can match the The phase change layer is matched in multiple directions, and the superlattice interlayer can provide an increase in the number of nucleation points for the phase change layer, and the increase in the number of nucleation points can shorten the crystallization time of the phase change layer and the corresponding crystallization time of the phase change material. , so that the phase change material can achieve ultra-fast read and write operations.

With reference to the first aspect, in a third possible implementation manner of the first aspect, the difference between the first atomic radius and the second atomic radius is less than or equal to an atomic radius threshold, and the first atomic radius is the superlattice interlayer The atomic radius of the contained atoms, and the second atomic radius is the atomic radius of the contained atoms of the phase change layer.

In this implementation manner, the difference between the first atomic radius and the second atomic radius is less than or equal to the atomic radius threshold, the superlattice interlayer and the phase change layer have a good lattice matching degree, and the superlattice interlayer can be compatible with the phase change layer. By matching in multiple directions, the superlattice interlayer can provide an increase in the number of nucleation points for the phase change layer, and the increase in the number of nucleation points can shorten the crystallization time of the phase change layer and the corresponding crystallization time of the phase change material, so that the Phase change materials enable ultra-fast read and write operations.

With reference to the first aspect, in a fourth possible implementation manner of the first aspect, the superlattice interlayer does not have phase change properties, and the melting point of the superlattice interlayer is greater than the melting point of the phase change layer.

In this implementation, since the phase transition temperature of the superlattice interlayer is greater than the melting point of the phase change layer, the reset process can increase the temperature to T3, and the melting point of T3 greater than the phase change layer is smaller than the phase transition temperature of the superlattice interlayer, so in Reset During the process, the superlattice interlayer can maintain a stable state; the Set process can raise the temperature to T4, and T4 is the crystallization temperature of the phase change layer less than T3 and less than the phase transition temperature of the superlattice interlayer, so the superlattice interlayer can be maintained during the Set process. stable state. Since both T3 and T4 are lower than the phase transition temperature of the superlattice interlayer, the superlattice interlayer will not undergo atomic migration during the heating process, so the problem of viscosity reduction in the superlattice interlayer will not occur.

In combination with the first aspect, in a fifth possible implementation manner of the first aspect, the superlattice interlayer has phase transition properties, the phase transition temperature of the superlattice interlayer is greater than that of the phase transition layer, and the phase transition temperature of the superlattice interlayer is greater than that of the phase transition layer. The transition temperature is greater than the melting point of the phase transition layer.

In this implementation, the superlattice interlayer can have phase transition properties. Since the phase transition temperature of the superlattice interlayer is greater than the melting point of the phase change layer, the Reset process can raise the temperature to T3, which is greater than the melting point of the phase change layer and smaller than the melting point of the superlattice layer. The phase transition temperature of the lattice interlayer, so the superlattice interlayer can maintain a stable state during the Reset process; the Set process can raise the temperature to T4, where T4 is the crystallization temperature of the phase change layer, which is less than T3 and less than the phase transition temperature of the superlattice interlayer. Therefore, the superlattice interlayer can maintain a stable state during the Set process. Since both T3 and T4 are lower than the phase transition temperature of the superlattice interlayer, the superlattice interlayer will not undergo atomic migration during the heating process, so the problem of viscosity reduction in the superlattice interlayer will not occur.

With reference to the first aspect, in a sixth possible implementation manner of the first aspect, the phase change layer further includes tellurium atoms Te, and the superlattice interlayer includes antimony atoms Sb.

In this implementation manner, the phase change layer may include antimony atoms and tellurium atoms, so as to further improve the thermal stability of the phase change material. The phase change layer is obtained by doping tellurium atoms and antimony atoms with each other. Tellurium atoms and antimony atoms can form strong chemical bonds. Therefore, in the amorphous state, tellurium atoms and antimony atoms become a stable compound. The thermal stability in the crystalline state is improved, and the thermal stability of the phase change material is improved.

With reference to the first aspect, in a seventh possible implementation manner of the first aspect, the phase change layer further includes tellurium atoms Te, and the superlattice interlayer includes tellurium atoms Te and scandium atoms Sc.

In this implementation manner, the superlattice interlayer may include tellurium atoms and scandium atoms, so as to take into account the thermal stability and crystallization time of the phase change material. The superlattice interlayer is doped with tellurium atoms and scandium atoms to obtain the compound ScTe. The compound ScTe is a stable compound, so the superlattice interlayer has good thermal stability, and the thermal stability of the corresponding phase change material can be improved. . Further, since the lattice constant of scandium atoms on the xy plane is similar to the lattice constant of antimony atoms on the xy plane, it is guaranteed that the superlattice interlayer lattice containing compound ScTe and the phase change layer lattice containing antimony atoms can To achieve multi-directional matching, the superlattice interlayer can provide nucleation points for the phase change layer in multiple directions, and the superlattice interlayer can provide the phase change layer with an increase in the number of nucleation points. time, the crystallization time of the phase change material is short.

With reference to the first aspect, in an eighth possible implementation manner of the first aspect, the thickness of the phase change layer is greater than or equal to 1 nm and less than or equal to 10 nm.

In this implementation manner, the thickness of the phase change layer is between 1 nm and 10 nm, so as to reduce the energy required in the reset process of the phase change material. Since the thickness of the phase change layer is between 1 nm and 10 nm, the melting point of the phase change layer is significantly reduced. Therefore, the energy required by the phase change layer in the Reset process is reduced, and the energy required by the phase change material in the Reset process is reduced. Further, since the thickness of the phase change layer is between 1 nm and 10 nm, in the amorphous state, the atomic density near the particle surface layer of the phase change layer is less, so the number of antimony atoms that can migrate during the crystallization process is less. Therefore, the number of voids generated due to the migration of antimony atoms is reduced to a certain extent, so that the viscosity of the phase change material is improved, and the application reliability and service life of the phase change material are improved.

In a second aspect, an embodiment of the present application provides a phase change material, the phase change material is antimony atom Sb, and the thickness of the phase change material is 1 nm-10 nm.

In this implementation manner, the thickness of the phase change material is between 1 nm and 10 nm, and the melting point of the phase change material is significantly reduced. Therefore, the energy required by the phase change material in the Reset process is reduced. Further, since the thickness of the phase change material is between 1 nm and 10 nm, in the amorphous state, the atomic density near the particle surface layer of the phase change layer is less, so the number of antimony atoms that can migrate during the crystallization process is relatively small. Therefore, the number of voids generated due to the migration of antimony atoms is reduced to a certain extent, so that the viscosity of the phase change material is improved, and the application reliability and service life of the phase change material are improved.

In a third aspect, an embodiment of the present application provides a phase change memory, including: a plurality of phase change memory cells, each phase change memory cell including the phase change material shown in the embodiment of the present application, a first electrode and a second electrode, The first electrode and the second electrode are connected through a phase change material.

In this implementation manner, the phase change memory has the beneficial effects of long service life, good application reliability, and maintaining normal operation under long-term multiple erasing and writing: compared with the phase change materials generally containing antimony atoms, the present application The phase change material provided in the embodiment has a relatively large viscosity, thereby improving the application reliability of the phase change memory prepared from the phase change material, prolonging the service life of the phase change memory, and ensuring that the phase change memory can last for a long time. It still keeps working normally even after several erasing.

Description of drawings

Fig. 1 is the structural schematic diagram of the lattice model of antimony element in the amorphous state;

Fig. 2 is the schematic diagram of the lattice structure of antimony-containing atoms in the crystalline state;

3 is a schematic diagram of the lattice structure of antimony-containing atoms in an amorphous state;

4 is a schematic diagram of a tellurium-containing atomic lattice structure provided in real time;

5 is a schematic structural diagram of a phase change memory disclosed in a feasible embodiment;

6 is a schematic structural diagram of another phase-change memory made of phase-change materials;

7 is a schematic structural diagram of a phase change memory disclosed in a feasible embodiment;

8 is a schematic structural diagram of a phase change memory disclosed in a feasible embodiment;

9 is a schematic structural diagram of a phase change memory disclosed in a feasible embodiment;

FIG. 10 is a schematic structural diagram of a phase change memory disclosed in a feasible embodiment.

Detailed ways

In this application, the phase change material is a material to which pulse signals of different amplitudes are applied, and the pulse signals of amplitude can be pulse currents, which can be mutually converted between a crystalline state and an amorphous state. In the amorphous state, the phase change material has a short-distance atomic energy level and a low free electron density, so that it has a high resistivity, and the amorphous state may also be referred to as a high-resistance state in this application. In the crystalline state, the phase change material has a long-distance atomic energy level and a high free electron density, and thus has a relatively low resistivity. In this application, the crystalline state may also be referred to as a low-resistance state. Utilizing the bistable (high-resistance and low-resistance) characteristics of phase change materials in electrical properties, different electrical pulse signals can be applied to them to maintain a high-resistance state or a low-resistance state.

In the present application, an amorphous state refers to a state in which atoms, ions or molecules are arranged disorderly within a crystal. The crystal state refers to the state in which atoms, ions or molecules are arranged spatially in a crystal. Therefore, the essence of the mutual conversion process of the phase change material between the crystalline state and the amorphous state is the process of the migration of atoms, ions or molecules inside the phase change material. The migration process includes the transformation of atoms, ions, and molecules from an ordered state to a disordered state (it can be called an amorphization process in this embodiment); it also includes the transformation of atoms, ions, and molecules from a disordered state to an ordered state (in the This embodiment may be referred to as a crystallization process). The distribution state of atoms in the crystalline state and the amorphous state will be described below with reference to the specific drawings. Figure 1 is a schematic diagram of the lattice structure of antimony atoms in the amorphous state. It can be seen that the antimony atoms 11 are arranged in a disordered state in the lattice. Figure 2 is a schematic diagram of the lattice structure of antimony atoms in the crystalline state. It can be seen that the antimony atoms are arranged in a hexagonal space sequence of 21 in the lattice.

Since the antimony atom Sb has good atomic mobility, the time required for the crystallization process or the time required for the deactivation process can be shortened, and the phase change materials shown in this embodiment all include antimony atoms.

In the phase change material containing antimony atoms, in the process of mutual conversion between the crystalline state and the amorphous state, the antimony atoms have good atomic migration properties, so that during the crystallization process, due to the migration of antimony atoms, the interior of the phase change material is A large number of voids are generated, and these voids will reduce the viscosity of the phase change material, causing the phase change materials to separate from each other, affecting the application reliability and service life of the phase change material.

Based on the above problems, the embodiments of the present application provide a phase change material, the phase change material includes: a phase change layer and a superlattice interlayer; the phase change layer and the superlattice interlayer form a superlattice structure, and the phase change layer includes antimony atoms;

In the present application, the phase change layer is the layer of material in the phase change material that can be mutually converted between a crystalline state and an amorphous state, and the thickness is within 100 nm. The phase change layer includes at least antimony atoms, and the antimony atoms have good atomic mobility, which can shorten the crystallization time of the phase change layer.

In this application, the superlattice interlayer is a material that can form a superlattice structure with the phase change layer, and the thickness is within 100 nm. The difference between a lattice constant and a second lattice parameter is less than or equal to a lattice parameter threshold, the first lattice constant is the lattice constant of the superlattice interlayer, and the second lattice constant is a phase transition The lattice constant of the lattice of the layer. The lattice parameter threshold can be set according to requirements, for example, in a feasible embodiment, the lattice parameter threshold is 0.01.

In this application, the superlattice structure refers to a periodic structure grown alternately between two materials with better lattice matching, and the thickness of each layer of material is below 100 nm. 3 is a schematic structural diagram of a phase change material disclosed in a feasible embodiment, the phase change material includes: a phase change layer 31 and a superlattice interlayer 32, and the phase change layer 31 and the superlattice interlayer 32 are alternately grown and periodically arranged into a superlattice structure.

The phase change material provided in the embodiment of the present application has the following beneficial effects: compared with the phase change material generally containing antimony atoms, the phase change material provided by the embodiment of the present application has a larger viscosity, better application reliability and relatively high viscosity. Long service life. When the first amplitude pulse signal is applied to the phase change material, the temperature of the phase change material rises above the crystallization temperature of the antimony atoms, the antimony atoms in the phase change layer are converted into a crystalline state, and the antimony atoms in the phase change layer are converted into crystals In the process of state, the superlattice interlayer remains in the crystalline state, and there is no migration of molecules, atoms or ions in the superlattice interlayer. It can migrate in the phase change layer, thus reducing the number of voids caused by the migration of antimony atoms to a certain extent. The application reliability and service life of the phase change material are improved; when the second amplitude pulse signal is applied to the phase change material, the temperature of the phase change material rises to above the melting point of the antimony atom, and then rapidly cools down, and the Antimony atoms are converted from crystalline state to amorphous state; there is no migration of molecules, atoms or ions in the superlattice interlayer, and the superlattice interlayer acts to limit the migration of antimony atoms in the phase change layer, so that antimony atoms can only be in Therefore, the number of voids generated due to the migration of antimony atoms is reduced to a certain extent, so that the viscosity of the phase change material is improved, and the application reliability and service life of the phase change material are improved.

In one embodiment, the phase change layer further includes tellurium atoms Te.

In this embodiment, the phase change material includes a phase change layer and a superlattice interlayer, and the thermal stability of the phase change layer affects the thermal stability of the phase change material. The thermal stability of the phase change layer is affected by the thermal stability of the phase change layer in the amorphous state. The better the thermal stability of the phase change layer in the amorphous state, the better the thermal stability of the corresponding phase change material, the stronger the application reliability of the phase change memory prepared from the phase change material, and the longer the service life of the phase change memory. long.

Considering the influence of the thermal stability of the phase change layer in the amorphous state on the service life of the phase change memory, as a feasible embodiment, the phase change layer may include antimony atoms and tellurium atoms to further improve the thermal stability of the phase change material . The phase change layer is obtained by doping between tellurium atoms and antimony atoms. The tellurium atoms and antimony atoms are uniformly and randomly distributed and form bonds. Since the atomic radius of the tellurium atom is similar to that of the antimony atom, in the process of bonding, the tellurium atom and the antimony atom are similar. The extranuclear electrons of the atom and the antimony atoms overlap to a greater extent, so that the tellurium atom and the antimony atom can form a strong chemical bond, so in the amorphous state, the tellurium atom and the antimony atom become a stable compound, and the phase transition The thermal stability of the layer in the amorphous state is improved, and the thermal stability of the phase change material is improved, thereby improving the reliability of the application of the phase change memory prepared from the phase change material, and prolonging the service life of the phase change memory, Ensure that the phase change memory can still maintain normal operation under long-term multiple erasing and writing.

In one embodiment, the phase change layer may further include tellurium atoms and rare earth atoms.

Generally, the crystal structure of the phase change layer in the amorphous state affects the stability of the phase change material. The more stable the crystal structure of the phase change layer in the amorphous state, the better the stability of the phase change material. The stronger the reliability of the application of the phase change memory prepared by the change material, the longer the service life of the phase change memory.

The compound formed by the tellurium atom and the antimony atom in the phase change layer has a lamellar structure in the amorphous state, and the crystal of the lamellar structure is less stable than the crystal of other structures.

Considering the influence of the crystal structure in the amorphous state of the phase change layer on the stability of the phase change material, as a feasible embodiment, the phase change layer may include: antimony atoms, tellurium atoms and rare earth atoms to further improve the stability of the phase change material. stability. Since antimony atoms, tellurium atoms and rare earth atoms can form ternary compounds, the crystal structure of this ternary compound is a non-lamellar structure in an amorphous state, so antimony atoms, tellurium atoms and rare earth atoms form ternary compounds with antimony atoms and Compared with the binary compound formed by tellurium atoms, the stability of the crystal structure is improved, the stability of the crystal structure of the phase change layer is improved, and the stability of the phase change material is improved, thereby improving the phase change memory prepared from the phase change material. The reliability of the application extends the service life of the phase change memory.

In one embodiment, the phase change layer may further include tellurium atoms and tin atoms Sn.

In general, the number of core points in the phase change layer affects the crystallization time of the phase change material. The more the number of core points in the phase change layer, the shorter the crystallization time of the phase change layer, the shorter the crystallization time of the phase change material, the higher the read and write efficiency of the phase change memory prepared from the phase change material, and the application of The better the convenience and functionality.

Considering the influence of the number of core points in the phase change layer on the crystallization time of the phase change material, as a feasible embodiment, the phase change layer may include antimony atoms, tellurium atoms and tin atoms to shorten the crystallization time of the phase change material. The phase change layer is obtained by doping tellurium atoms, antimony atoms and tin atoms with each other. Since the atomic radius of the tellurium atom is similar to that of the antimony atom, the tellurium atom and the antimony atom can form a strong chemical bond. In this state, tellurium atoms and antimony atoms become a stable compound. Doping tin atoms in this compound can increase the number of nuclei in the crystallization process, and the increase in the number of nuclei can shorten the crystallization time of the phase change layer. The crystallization time of the phase change material is short, so that the phase change memory prepared from the phase change material can realize fast read and write operations, the data read and write efficiency of the phase change memory can be improved, and the application convenience and functionality of the phase change memory can be improved. promote.

In one embodiment, the thickness of the phase change layer is between 1 nm and 10 nm.

In the process of mutual conversion between the crystalline state and the amorphous state of the phase change material, the temperature of the phase change material needs to be increased. For example: the process of converting the phase change material from an amorphous state to a crystalline state (it can be called a Set process in this embodiment): a long and medium-intensity pulse signal needs to be applied to the phase change material to make the phase change material The temperature is raised above the crystallization temperature and below the melting point, and maintained for a period of time, so that the phase change material is transformed into a crystalline state, at which time the phase change material exhibits a low resistance state. For another example, the process of converting a phase change material from a crystalline state to an amorphous state can also be referred to as a Reset process, and the Reset process applies a long and strong amplitude pulse signal (also referred to as a Reset current in this application) to the phase change material. ), so that the temperature of the phase change material is raised above the melting point, and then rapidly cooled, the phase change material is transformed into an amorphous state, and the phase change material exhibits a high resistance state at this time.

The reset current is an important parameter of the phase change memory. The smaller the reset current, the smaller the energy required in the reset process. It is generally desirable to lower the melting point of the phase change material to reduce the energy required in the reset process of the phase change material.

Under normal circumstances, when the size of the material is in the nanometer level, its fixed melting point is significantly reduced, and when the size of the material is less than 10 nm, the phenomenon of melting point reduction is particularly significant. At the same time, when the size of the material is on the nanometer scale, in the amorphous state, the density of atoms near the surface layer of the material is less.

Considering the influence of the size of the material on the energy required in the reset process of the phase change material, as a feasible embodiment, the thickness of the phase change layer is 1 nm-10 nm, so as to reduce the energy required in the reset process of the phase change material. Since the thickness of the phase change layer is between 1 nm and 10 nm, the melting point of the phase change layer is significantly reduced. Therefore, the energy required by the phase change layer in the Reset process is reduced, and the energy required by the phase change material in the Reset process is reduced. The power consumption of the phase change memory fabricated from the phase change material. Further, since the thickness of the phase change layer is between 1 nm and 10 nm, in the amorphous state, the atomic density near the particle surface layer of the phase change layer is less, so the number of antimony atoms that can migrate during the crystallization process is less. , so to a certain extent, the number of voids generated due to the migration of antimony atoms is reduced, the viscosity of the phase change material is improved, and the application reliability and service life of the phase change material are improved, thereby improving the performance of the phase change material. The application reliability of the prepared phase-change memory extends the service life of the phase-change memory, and ensures that the phase-change memory can still maintain normal operation under multiple erasing and writing for a long time.

In one embodiment, the superlattice interlayer includes tellurium atoms Te.

In this embodiment, the superlattice interlayer and the phase change layer can form a superlattice structure, that is, the superlattice interlayer and the phase change layer are alternately and periodically arranged, and multiple interfaces are formed between the superlattice interlayer and the phase change layer. During the Set process of the phase change layer, the superlattice interlayer at the interface can provide a nucleus point for the phase change layer.

In the present application, a nucleus point is a point that can provide a crystal nucleus for the phase change layer during the crystallization process of the phase change layer.

Usually, the difference between the first atomic radius and the second atomic radius is less than or equal to the atomic radius threshold, the lattice of the superlattice interlayer and the phase change layer have a good lattice match, and the superlattice interlayer can provide the phase change layer. The more nuclei, the shorter the crystallization time of the phase change layer and the shorter the crystallization time of the phase change material, wherein the first atomic radius is the atomic radius of the atoms contained in the superlattice interlayer, and the second atomic radius is the atomic radius of the atoms contained in the superlattice interlayer. The atomic radius is the atomic radius of the atoms contained in the phase change layer. The atomic radius threshold may be set according to requirements, for example, in a feasible embodiment, the atomic radius threshold may be 2pm.

Considering the influence of the number of nucleation points that the superlattice interlayer can provide for the phase change layer on the crystallization time of the phase change material, as a feasible example, the superlattice interlayer can include tellurium atoms to shorten the crystallization of the phase change material. time. The phase change layer includes antimony atoms, and the lattice structure of the antimony element in the crystal state can continue to refer to FIG. 2 , it can be seen that the lattice structure of the antimony atoms is a hexagonal structure. In this embodiment, the superlattice interlayer includes tellurium atoms, and the lattice structure of the tellurium atoms can be seen in FIG. 4 . FIG. 4 is a schematic diagram of the lattice structure containing the tellurium atoms provided in real time. It can be seen that the lattice of the tellurium atoms 41 The structure is a hexagonal structure, so the superlattice interlayer lattice has a good matching degree with the phase change layer lattice. Further, because the atomic radius of the tellurium atom is similar to that of the antimony atom, the superlattice interlayer lattice is The degree of matching with the lattice of the phase change layer is further improved, thereby ensuring that the lattice of the superlattice interlayer and the lattice of the phase change layer can achieve multi-directional matching, and the superlattice interlayer can provide an increase in the number of nuclei for the phase change layer , the increase in the number of nuclei can shorten the crystallization time of the phase change layer, and the crystallization time of the corresponding phase change material, so that the phase change material can realize ultra-fast read and write operations, and improve the process of the phase change material. The data read and write efficiency of the phase change memory improves the convenience and functionality of the phase change memory application.

In one embodiment, the superlattice interlayer may include tellurium atoms and scandium atoms Sc.

In this embodiment, the phase change material includes a phase change layer and a superlattice interlayer, and the thermal stability of the superlattice interlayer affects the thermal stability of the phase change material. The better the thermal stability of the superlattice interlayer, the better the thermal stability of the phase change material. At the same time, the better the matching degree between the lattice of the superlattice interlayer and the lattice of the phase change layer is, the more the superlattice interlayer can provide the nucleation point for the phase change layer, the shorter the crystallization time of the phase change layer, and the crystallisation of the phase change material. shorter time.

Taking into account the thermal stability of the superlattice interlayer and the influence of the number of nuclei that the superlattice interlayer can provide for the phase change layer on the phase change material, as a feasible embodiment, the superlattice interlayer can include tellurium atoms and scandium atoms, In order to take into account the thermal stability and crystallization time of the phase change material. The superlattice interlayer is doped with tellurium atoms Te and scandium atoms Sc to obtain the compound ScTe. The compound ScTe is a stable compound without phase transition properties. The melting point can reach 1300K, so the superlattice interlayer has good thermal stability. The thermal stability of the corresponding phase change material is improved, thereby improving the application reliability of the phase change memory prepared from the phase change material, prolonging the service life of the phase change memory, and ensuring that the phase change memory can be used for a long time. After multiple erasing and writing, it still keeps working normally. Further, since the lattice constant of scandium atoms on the xy plane is similar to the lattice constant of antimony atoms on the xy plane, it is guaranteed that the superlattice interlayer lattice containing compound ScTe and the phase change layer lattice containing antimony atoms can To achieve multi-directional matching, the superlattice interlayer can provide nucleation points for the phase change layer in multiple directions, and the superlattice interlayer can provide the phase change layer with an increase in the number of nucleation points. The crystallization time of the phase change material is short, so that the phase change material can realize ultra-fast read and write operations, improve the data read and write efficiency of the phase change memory prepared from the phase change material, and improve the read and write efficiency of the phase change material. Convenience and functionality of fabricated phase change memory applications.

As an achievable manner, the superlattice interlayer has no phase change property, and the melting point of the superlattice interlayer is greater than the melting point of the phase change layer. During the repeated erasing and writing of the phase change memory, the temperature of the phase change material needs to be increased. In this embodiment, the superlattice interlayer does not have phase transition properties, so the superlattice interlayer will not undergo atomic migration during the heating process, so the problem of viscosity reduction in the superlattice interlayer will not occur. Further, since the melting point of the superlattice interlayer is greater than the melting point of the phase change layer, the reset process can increase the temperature to T1, and the melting point of T1 greater than the phase change layer is smaller than the melting point of the superlattice interlayer, so the superlattice interlayer in the Reset process can be Maintain a stable state; the Set process can raise the temperature to T2, and T2 is the crystallization temperature of the phase change layer less than T1 and less than the melting point of the superlattice interlayer, so the superlattice interlayer can maintain a stable state during the Set process.

As an achievable manner, the superlattice interlayer has phase transition properties, and the phase transition temperature of the superlattice interlayer is greater than the melting point of the phase transition layer. During the repeated erasing and writing of the phase change memory, the temperature of the phase change material needs to be increased. In this embodiment, the superlattice interlayer may have phase transition properties. Since the phase transition temperature of the superlattice interlayer is greater than the melting point of the phase change layer, the reset process can raise the temperature to T3, which is greater than the melting point of the phase change layer and smaller than the melting point of the superlattice layer. The phase transition temperature of the lattice interlayer, so the superlattice interlayer can maintain a stable state during the Reset process; the Set process can raise the temperature to T4, where T4 is the crystallization temperature of the phase change layer, which is less than T3 and less than the phase transition temperature of the superlattice interlayer. Therefore, the superlattice interlayer can maintain a stable state during the Set process. Since both T3 and T4 are lower than the phase transition temperature of the superlattice interlayer, the superlattice interlayer will not undergo atomic migration during the heating process, so the problem of viscosity reduction in the superlattice interlayer will not occur.

The embodiment of the present application provides a phase change material, the phase change material is antimony atom Sb, and the thickness of the phase change material is 1 nm to 10 nm; when a first amplitude pulse signal is applied to the phase change material, the phase change material heats up to the crystal of the antimony atom. Above the melting temperature, the antimony atoms in the phase change material are converted into a crystalline state; when the second amplitude pulse signal is applied to the phase change material, the phase change material heats up to above the melting point of the antimony atoms and cools down, and the antimony atoms in the phase change material are changed from The crystalline state is converted to an amorphous state.

The phase change material provided in the embodiments of the present application has the following beneficial effects: the thickness of the phase change material is between 1 nm and 10 nm, and the melting point of the phase change material is significantly reduced. Therefore, the energy required by the phase change material in the reset process is reduced. Further, since the thickness of the phase change material is between 1 nm and 10 nm, in the amorphous state, the atomic density near the particle surface layer of the phase change layer is less, so the number of antimony atoms that can migrate during the crystallization process is relatively small. Therefore, the number of voids generated due to the migration of antimony atoms is reduced to a certain extent, so that the viscosity of the phase change material is improved, and the application reliability and service life of the phase change material are improved.

As shown in FIG. 5 , which is a schematic structural diagram of a phase change memory fabricated by using the above phase change material, the phase change memory may include a first electrode 51 , a phase change material 52 and a second electrode 53 . The upper surface of the first electrode 511 is provided with a phase change material 52 , and the upper surface of the phase change material 52 is provided with a second electrode 53 ; the first electrode 51 , the phase change material 52 and the second electrode 53 are arranged in parallel.

FIG. 6 is a schematic structural diagram of another phase change memory fabricated by using the above-mentioned phase change material. In this embodiment, the upper surface of the first electrode 61 is provided with a phase change material 62 , and the upper surface of the phase change material 62 is provided with a phase change material 62 . Two electrodes 63; the first electrode 61 and the second electrode 63 are arranged at a certain angle. In this application, the angle between the first electrode 61 and the second electrode 63 is not limited in degrees, and the angle between the first electrode 61 and the second electrode 63 can be set according to requirements in the actual application process. .

As an achievable manner, the cross section of the phase change material in the vertical direction may be smaller than the cross section of the first electrode or the second electrode in the vertical direction, so as to achieve the purpose of saving the phase change material.

The phase-change memory provided by the embodiment of the present application has the beneficial effects of long service life, good application reliability, and normal operation under long-term multiple erasing and writing: compared with the phase-change material generally containing antimony atoms, this The phase change materials provided in the application examples have relatively large viscosity. When the first amplitude pulse signal is applied to the above phase change material, the antimony atoms in the phase change layer are converted into a crystalline state. There is no migration of molecules, atoms or ions in the lattice interlayer, and the superlattice interlayer plays a role in restricting the migration of antimony atoms in the phase change layer, so that antimony atoms can only migrate in the phase change layer, thus reducing to a certain extent the The number of voids generated by the migration of antimony atoms increases the viscosity of the phase change material, and improves the application reliability and service life of the phase change material; when the second amplitude pulse signal is applied to the phase change material, the phase change layer The antimony atoms are converted into an amorphous state, and there is no migration of molecules, atoms or ions in the superlattice interlayer. Therefore, the number of voids generated due to the migration of antimony atoms is reduced to a certain extent, so that the viscosity of the phase change material is improved, and the application reliability and service life of the phase change material are improved, thereby improving the phase change material. The reliability of the application of the phase change memory prepared by the material can prolong the service life of the phase change memory, and ensure that the phase change memory can still maintain normal operation under multiple erasing and writing for a long time.

It is worth noting that, FIG. 5 and FIG. 6 only exemplify two possible structures of the phase change memory, but do not limit the scope of this embodiment.

As a feasible implementation manner, the material of the first electrode may include: one of W, Al, Cu, Ru, Ti, Ta, Co, Mo, Ir, Ni, Nb, TiN, TaN, TiW, IrO2 or several. It is worth noting that this embodiment is only an example of several materials of the first electrode, rather than limiting the scope of this embodiment. In the process of practical application, any material that can play a conductive role can be used as The material of the first electrode.

As a feasible implementation manner, the material of the second electrode may include: one of W, Al, Cu, Ru, Ti, Ta, Co, Mo, Ir, Ni, Nb, TiN, TaN, TiW, IrO2 or several. It is worth noting that this embodiment is only an example of several materials for the second electrode, rather than limiting the scope of this embodiment. In the process of practical application, any material that can play a conductive role can be used as The material of the second electrode.

In some embodiments, the phase change memory may further include a substrate, and the substrate is disposed on the surface of the first electrode and plays a role of supporting and protecting the first electrode. The phase change memory provided in this embodiment will be further described below with reference to the specific drawings.

FIG. 7 is a schematic structural diagram of a phase change memory disclosed in a feasible embodiment. It can be seen that the phase change memory may include: a first electrode 71 , a phase change material 72 , a second electrode 73 and a substrate 74 . In the figure, the substrate 74 is disposed on the lower surface of the first electrode 71 to support the first electrode 71; the upper surface of the first electrode 71 is provided with a phase change material 72, and the upper side of the phase change material 72 is provided with a first electrode 72. Two electrodes 73 . It is worth noting that FIG. 7 merely exemplifies a possible structure of a phase change memory, rather than limiting the scope of this embodiment.

As a feasible implementation manner, the material of the substrate may include one or more of silicon, silicon oxide, sapphire, silicon carbide, and gallium nitride. It is worth noting that this embodiment is only an example of several substrate materials, rather than limiting the scope of this embodiment. In the process of practical application, all can play the role of supporting and protecting the first electrode Any material can be used as the material of the substrate.

In some embodiments, the phase change memory may further include: an insulating layer. The phase change memory provided in this embodiment will be further described below with reference to the specific drawings.

8 is a schematic structural diagram of a phase change memory disclosed in a feasible embodiment. It can be seen that the phase change memory may include: a first electrode 81 , a phase change material 82 , a second electrode 83 , a substrate 84 and an insulating layer 85 . In the figure, the substrate 84 is disposed on the lower surface of the first electrode 81 to support the first electrode 81; the upper surface of the first electrode 81 is provided with an insulating layer 85, and the insulating layer 85 is provided with a through hole (Fig. The phase change material 82 is arranged in the through hole, and the lower surface of the phase change material is connected with the first electrode 81 . A second electrode 83 is disposed on the upper surface of the insulating layer 85; the second electrode 83 covers the through hole and is connected to the second surface of the phase change material 82 disposed inside the through hole.

The phase change memory shown in this embodiment further includes an insulating layer, and the insulating layer is disposed on the outer surface of the phase change material to protect the phase change material.

9 is a schematic structural diagram of a phase change memory disclosed in a feasible embodiment. It can be seen that the phase change memory may include: a first electrode 91 , a phase change material 92 , a second electrode 93 , a substrate 94 and an insulating layer 95 . In the figure, the substrate 94 is disposed on the lower surface of the first electrode 91 to support the first electrode 91; the upper surface of the first electrode 91 is provided with an insulating layer 95, and the insulating layer 95 is provided with through holes (Fig. The cross section of the phase change material 92 in the vertical direction is in a "T" shape, and the phase change material 92 includes: a first sub-component 921 and a second sub-component 922, the first sub-component 921 is placed horizontally, and the second sub-component 921 is placed horizontally. The upper surface of the sub-component 922 is connected to the lower surface of the first sub-component 921, and the second sub-component 922 is connected to the first electrode 91 through the through hole; the first sub-component 921 is arranged on the upper surface of the insulating layer 95, and the first sub-component 922 The upper surface of the 921 is provided with the second electrode 93 .

The phase change memory shown in this embodiment further includes an insulating layer. The insulating layer is provided on the outer surface of the second sub-component to protect the second sub-component. Further, the insulating layer is provided on the first sub-component and the first electrode. In between, it plays the role of supporting the first sub-component.

In the application scenario where the substrate is made of conductive material, if the first electrode is directly arranged on the upper surface of the substrate, the problem of leakage current will be caused. In order to solve the above technical problem, this embodiment shows a phase change memory. The accompanying drawings further illustrate the phase change memory provided in this embodiment.

10 is a schematic diagram of a phase change memory disclosed in a feasible embodiment. It can be seen that the phase change memory may include: a first electrode 101, a phase change material 102, a second electrode 103, a substrate 104 and an insulating layer 105. In this embodiment In an example, the substrate 104 is fabricated from a conductive material. In the figure, the insulating layer 105 is provided on the upper surface of the substrate 104; the phase change material 102 is provided on the upper surface of the insulating layer 105; The upper surface; the second electrode 103 is partially arranged on the upper surface of the insulating layer 105 , and partly arranged on the upper surface of the phase change material 102 .

The phase change memory shown in this embodiment uses an insulating material to isolate the substrate from the phase change material, the substrate from the first electrode, and the substrate from the first electrode. Even in an application scenario where a substrate of a conductive material is used, the There is a leakage problem.

It is worth noting that, FIG. 8 , FIG. 9 , and FIG. 10 only exemplify several possible structures of the phase change memory, but do not limit the scope of this embodiment.

The present application also provides a method for preparing a phase change material. Specifically, the present application can be prepared by any one of chemical electroplating, magnetron sputtering, chemical vapor deposition, pulsed laser, atomic layer deposition or electron beam evaporation. Phase change materials shown in the examples.

The present application also provides a method for preparing a phase change memory, the method comprising:

preparing a first electrode, a phase change material and a second electrode;

The prepared first electrode phase change material and the second electrode are integrated into a phase change memory.

As a feasible real-time method, the first electrode can be prepared by chemical plating, magnetron sputtering, chemical vapor deposition, pulsed laser, atomic layer deposition or electron beam evaporation.

As a feasible real-time method, chemical plating, magnetron sputtering, chemical vapor deposition, pulsed laser, atomic layer deposition or electron beam evaporation can be used to prepare the phase change material shown in this embodiment.

As a feasible real-time method, the second electrode can be prepared by chemical plating, magnetron sputtering, chemical vapor deposition, pulsed laser, atomic layer deposition or electron beam evaporation.

The present application also provides a memory, which includes the phase change memory shown in the embodiment of the present application and a storage unit connected to the phase change memory.

As a feasible embodiment, the memory may include a phase change memory, a resistive memory, a magnetic memory, a ferroelectric memory, and the like. It is worth noting that this embodiment is only an exemplary form in which the memory may exist, and does not limit the scope of this embodiment.

A computer is also provided in the present application. The computer includes the memory shown in the embodiment of the present application and the processor connected to the memory.

The computer involved in the embodiments of the present application may be a mobile phone, a tablet computer, a notebook computer, an ultra-mobile personal computer (UMPC), a handheld computer, a netbook, a personal digital assistant (PDA), and a wearable terminal. , vehicle-mounted equipment, virtual reality equipment, etc., the embodiments of the present application do not impose any restrictions on this.

It should be understood that the multiple involved in the embodiments of the present application refers to two or more. In addition, it should be understood that in the description provided by the embodiments of the present application, terms such as "first" and "second" are only used for the purpose of distinguishing the description, and should not be construed as indicating or implying relative importance, nor understood as indicating or implying a sequence. The same and similar parts among the various embodiments in this specification may be referred to each other, and the above-mentioned embodiments do not constitute a limitation on the protection scope of the present application. Various modifications and variations of this application are possible for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles provided by the embodiments of the present application shall be included within the protection scope provided by the embodiments of the present application.

Claims

A phase change material suitable for a phase change memory, characterized in that the phase change material comprises: a phase change layer and a superlattice interlayer; the phase change layer and the superlattice interlayer form a superlattice structure, The phase change layer includes antimony atoms Sb; the superlattice interlayer is in a crystalline state when the phase change layer transitions between a crystalline state and an amorphous state.
The phase change material according to claim 1, wherein the superlattice interlayers and the phase change layers are alternately arranged, and a plurality of interfaces are formed between the superlattice interlayers and the phase change layers, The superlattice interlayer provides a nucleus point for the phase change layer at the location of the interface when the phase change layer is transformed into a crystalline state.
The phase change material according to claim 1 or 2, wherein the difference between the first lattice constant and the second lattice parameter is less than or equal to a lattice parameter threshold, and the first lattice constant is the super The lattice constant of the lattice interlayer, and the second lattice constant is the lattice constant of the phase change layer.
The phase change material according to claim 1 or 2, wherein the difference between the first atomic radius and the second atomic radius is less than or equal to an atomic radius threshold, and the first atomic radius is the superlattice interlayer comprising The atomic radius of the atom, and the second atomic radius is the atomic radius of the atoms contained in the phase change layer.
The phase change material according to any one of claims 1-4, wherein the superlattice interlayer has no phase change property, and the melting point of the superlattice interlayer is greater than the melting point of the phase change layer.
The phase change material according to any one of claims 1 to 4, wherein the superlattice interlayer has phase change properties, and the phase transition temperature of the superlattice interlayer is greater than that of the phase change layer temperature, the phase transition temperature of the superlattice interlayer is greater than the melting point of the phase transition layer.
The phase change material according to any one of claims 1-6, wherein the phase change layer further comprises tellurium atoms Te, and the superlattice interlayer comprises tellurium atoms Te.
The phase change material according to any one of claims 1-6, wherein the phase change layer further comprises tellurium atoms Te, and the superlattice interlayer comprises tellurium atoms Te and scandium atoms Sc.
The phase change material according to any one of claims 1-7, wherein the thickness of the phase change layer is greater than or equal to 1 nm and less than or equal to 10 nm.
A phase change memory, comprising a plurality of phase change memory cells, each phase change memory cell comprising the phase change material according to any one of claims 1-9, a first electrode and a second electrode, the first electrode and the The second electrode is connected through the phase change material.