WO2015196412A1

WO2015196412A1 - Metal doped ge-sb-te-based multivalue storage phase-change material and phase-change memory

Info

Publication number: WO2015196412A1
Application number: PCT/CN2014/080823
Authority: WO
Inventors: 缪向水; 余念念; 童浩; 徐荣刚; 赵俊峰; 张树杰
Original assignee: 华为技术有限公司
Priority date: 2014-06-26
Filing date: 2014-06-26
Publication date: 2015-12-30
Also published as: CN105393375A; CN105393375B

Abstract

A metal doped Ge-Sb-Te-based multivalue storage phase-change material, represented by general formula M_X(Ge_aSb_bTe_c)_1-X, wherein M is a doping metal element, M is at least one of Cu, Ag and Zn, x represents the atom number percentage of M, 0<x<20%, and M is uniformly distributed among the Ge_aSb_bTe_c. Under an externally applied impulse voltage or impulse current, three-state storage in an amorphous high-resistance state, an amorphous low-resistance state and a crystalline low-resistance state of the phase-change material is achieved, the states are apparently distinguished, the intermediate resistance state is highly controllable, a small electric field is required to acquire the intermediate resistance state, the power consumption is low, and the acquired intermediate resistance state has good stability and good repeatability. Also provided is a phase-change memory comprising the metal doped Ge-Sb-Te-based multivalue storage phase-change material.

Description

Metal-doped Ge-Sb-Te based multi-value storage phase change material and phase change memory

The present invention relates to the field of phase change memory materials, and more particularly to a metal doped Ge-Sb-Te based multi-value storage phase change material and phase change memory. Background technique

Phase change memory has become one of the mainstream semiconductor memory products in the future due to its outstanding technical advantages and the International Semiconductor Industry Association's belief that it can replace flash memory and dynamic random access. At present, research on phase change memory mainly focuses on high speed and low power consumption. In order to meet the requirements of massive information storage, high-density storage research of phase change memory is particularly important.

Conventional methods for implementing high-density phase-change memories include: reducing the area of the phase-change unit and reducing the area of the peripheral circuit. The former requires improvement of the device structure and is limited by the size of the lithography; the latter requires optimization of the integrated circuit design. The problem of the above conventional method can be avoided if the difference in resistance between the crystalline state and the amorphous state (usually several tens to hundreds of times) can be fully utilized to realize multi-value storage of more than 2 bits. This greatly expands the memory capacity based on existing phase change memory lithography and integrated circuit design.

At present, the multi-value storage materials reported in the industry are mostly mainstream phase change materials (Ge-Sb-Te-based phase change materials) doped with non-metallic elements or doped with non-mainstream phase change materials. The former has an intermediate resistance state that is difficult to control and needs. The electric field is large, the energy consumption is high, and the latter has the disadvantages of poor phase transition performance and unstable intermediate state. Summary of the invention

In view of this, the first aspect of the present invention provides a metal-doped Ge-Sb-Te based multi-value storage phase change material for solving the poor phase change performance of the multi-valued storage material in the prior art. , medium Problems such as unstable state of the environment and high energy consumption.

In a first aspect, an embodiment of the present invention provides a metal-doped Ge-Sb-Te based multi-value storage phase change material, wherein the storage phase change material has the general formula: M GeaSbbTeJn, wherein M is a doped metal element The M is at least one of Cu, Ag, and Zn, and X represents a percentage of the number of atoms of M, 0 < x < 20%, and the M is uniformly dispersed in Ge _a Sb _b Te _c .

In an embodiment of the invention, the phase change material is M GezSbzTeA^

In an embodiment of the invention, the phase change material is M Ge^bzTe^^

In an embodiment of the invention, the phase change material is M _x (Ge ₂ Sb ₂ Te ₄ )k.

In an embodiment of the invention, the phase change material is M _x (Ge ₃ Sb ₄ Te ₈ )k.

In the embodiment of the present invention, by applying a pulse voltage or a pulse current to the phase change material, the phase change material may be in three different states of an amorphous high resistance state, an amorphous low resistance state, and a crystalline low resistance state. Convert to achieve multi-value storage.

In the embodiment of the present invention, by applying a first pulse voltage or a pulse current to the phase change material, the doped metal element M atom can form a conductive path between the two poles to realize an amorphous high resistance state to an amorphous low resistance. Transition of the state, by applying a second pulse voltage or a pulse current to the phase change material to crystallize the phase change material to achieve a transition from an amorphous low resistance state to a crystalline low resistance state, the first pulse voltage or The pulse current is less than or equal to 1/2 of the second pulse voltage or pulse current.

In an embodiment of the invention, the first pulse voltage is 0.25V-1V; and the second pulse voltage is 0.5V-2V.

In an embodiment of the invention, the magnitude of the change in resistance between the amorphous high resistance state and the crystalline low resistance state is more than two orders of magnitude.

In an embodiment of the invention, the phase change material is sputtered, electron beam evaporated, vapor deposited Prepared by law or atomic layer deposition.

In an embodiment of the invention, the phase change material is formed by co-sputtering with four elemental targets of Ge, Sb, Te, metal M and under an inert gas atmosphere.

In an embodiment of the invention, the phase change material is formed by co-sputtering with a Ge-Sb-Te alloy target and a metal M elemental target under an inert gas atmosphere.

The metal-doped Ge-Sb-Te-based multi-value storage phase change material provided by the first aspect of the present invention can realize amorphous high-resistance state, amorphous low-resistance state, and crystal under external pulse voltage or pulse current. Three-state storage of low-resistance state, the distinction between each state is obvious and the intermediate resistance state is controllable, the electric field required to obtain the intermediate resistance state is small, the energy consumption is low, and the metal atom in the amorphous phase change material is utilized. The intermediate resistance state obtained by forming a conductive path under the action of an electric field has good stability and good repeatability.

In a second aspect, an embodiment of the present invention provides a phase change memory including a phase change memory unit, wherein the phase change memory unit includes a top electrode, a first isolation layer, and a phase change memory material film layer sequentially disposed on a substrate. a second isolation layer and a lower electrode, wherein the top electrode is in electrical contact with the phase change memory material film layer, and the material of the phase change memory material film layer is metal doped according to the first aspect of the present invention. Ge-Sb-Te based multi-value storage phase change material.

In an embodiment of the invention, the phase change memory material thin film layer has a thickness of 10 nm to 120 nm. The phase change memory provided by the second aspect of the present invention can realize a three-state storage of an amorphous high-resistance state, an amorphous low-resistance state, and a crystalline low-resistance state under an applied pulse voltage or pulse current, and can realize high density. Multi-value storage, high stability, good repeatability, and based on the traditional phase change memory cell structure, no process complexity is improved, the programming method is simple, and there is no improvement in circuit design complexity.

The advantages of the embodiments of the present invention will be set forth in part in the description which follows. DRAWINGS

Figure 1 shows the NaCl-type atomic arrangement of the GST crystalline film;

2 is a microstructure of a metal-doped Ge-Sb-Te based multi-value storage phase change material in a crystallization low resistance state, an amorphous low resistance state, and an amorphous high resistance state according to an embodiment of the present invention;

3 is a schematic structural diagram of a phase change memory cell of a metal-doped Ge-Sb-Te based multi-value storage phase change material according to an embodiment of the present invention;

4 is a schematic diagram of a pulse for realizing multi-value storage of a phase change memory according to Embodiment 1 of the present invention; FIG. 5 is a pulse test result of a memory cell of a phase change memory according to Embodiment 1 of the present invention. detailed description

The following are the preferred embodiments of the embodiments of the present invention, and it should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the embodiments of the present invention. And retouching is also considered to be the scope of protection of the embodiments of the present invention.

The first aspect of the present invention provides a metal-doped Ge-Sb-Te-based multi-valued storage phase change material, which is used to solve the problem that the multi-value storage material in the prior art has poor phase transition performance and the intermediate state is unstable. , high energy consumption and other issues.

In an embodiment of the invention, the phase change material is M GezSbzTe^^

In an embodiment of the invention, the phase change material is M Ge^bzTe ^ In an embodiment of the invention, the phase change material is

The atomic arrangement of the GST (Ge-Sb-Te) film is shown in Figure 1. It is a NaCl-type atomic arrangement. In its structure, there are lattice points that are not filled with atoms, that is, vacancies. The ratio of vacancies to the entire lattice is Vacancy rate. Since the Ge-Sb-Te-based phase change material has a vacancy rate of 10% to 20%, it provides a space for migration of metal atoms. The metal has good electrical conductivity. The Ge-Sb-Te-based phase change material is doped with a small atomic radius and a relatively active metal material Cu (128pm), Ag (144pm), Zn (133pm), when no applied voltage. When the metal atoms are uniformly dispersed in the Ge-Sb-Te-based phase change material, the microstructure is as shown in Fig. 2A, and the amorphous state is high. When a certain voltage is applied to the upper and lower ends of the amorphous Ge-Sb-Te-based phase change material, the metal atoms migrate under the action of the electric field to form a conductive path between the upper and lower electrodes. The energy provided by the electric field is sufficiently low to ensure that the phase change material is still amorphous, thereby obtaining an amorphous low resistance state between the amorphous high resistance state and the crystalline low resistance state, and the microstructure at this time is as shown in FIG. 2 . B shows. Continue to increase the voltage until the phase transition of the cell reaches the crystalline low-resistance state. The microstructure at this time is shown in Figure 2C. M in Fig. 2 is a metal atom. The amorphous low-resistance state obtained by using the conductive channel formed by the doped metal atom at a low voltage forms a tri-state memory with the amorphous high-resistance state and the polycrystalline low-resistance state of the phase change material itself, thereby realizing high density. storage.

In an embodiment of the invention, the phase change material is prepared by a sputtering method, an electron beam evaporation method, a vapor deposition method or an atomic layer deposition method.

In a second aspect, an embodiment of the present invention provides a phase change memory including a phase change memory unit, wherein the phase change memory unit includes a top electrode, a first isolation layer, and a phase change memory material film layer sequentially disposed on a substrate. a second isolation layer and a lower electrode, wherein the top electrode is in electrical contact with the phase change memory material film layer, and the material of the phase change memory material film layer is metal doped according to the first aspect of the present invention. Ge-Sb-Te based multi-value storage phase change material. In an embodiment of the invention, the phase change memory material thin film layer has a thickness of 10 nm to 120 nm. In the embodiment of the present invention, the materials of the substrate, the top electrode, the lower electrode, the first isolation layer and the second isolation layer are not particularly limited, and may be commonly used.

In an embodiment of the invention, the material of the substrate is Si0 ₂ .

In the embodiment of the invention, the material of the top electrode and the lower electrode is TiW.

In the embodiment of the present invention, the materials of the first isolation layer and the second isolation layer are both SiO ₂ . The phase change memory provided by the second aspect of the present invention can realize a three-state storage of an amorphous high-resistance state, an amorphous low-resistance state, and a crystalline low-resistance state under an applied pulse voltage or pulse current, and can realize high density. Multi-value storage, high stability, good repeatability, and based on the traditional phase change memory cell structure, no process complexity is improved, the programming method is simple, and there is no improvement in circuit design complexity.

The embodiments of the present invention are further described below in various embodiments. The embodiments of the present invention are not limited to the specific embodiments below. Changes can be implemented as appropriate within the scope of the invariable principal rights.

Embodiment 1

A Cu-doped Ge ₂ Sb ₂ Te ₅ phase change memory material having the structural formula: Cu _x (Ge ₂ Sb ₂ Te _{5 x} , wherein x=5%, and the other elements are Cu, Ge, Sb, Te The target is co-sputtered.

A phase change memory is prepared by using Ci GezSbzTes) as a material of a phase change memory material film layer. The phase change memory cell of the phase change memory is shown in FIG. 3, and includes a top electrode 10, which is sequentially disposed on the substrate 101. An isolation layer 20, a phase change memory material film layer 30, a second isolation layer 40, a lower electrode 50, and a top electrode 10 are in electrical contact with the phase change memory material film layer 30. The top electrode 10 and the lower electrode 50 are made of TiW, and have a thickness. The material of the first isolation layer 20 and the second isolation layer 40 is Si0 ₂ and the thickness is 100 nm, and the material of the phase change memory material film layer 30 is 200 nm.

The thickness is 120 nm. Embodiment 2

An Ag-doped Ge ₂ Sb ₂ Te ₅ phase change memory material having the structural formula: Ag _x (Ge ₂ Sb ₂ Te ₅ ) _1-x , wherein x=10%, and its use of Ag, Ge, Sb, Te Four elemental targets are co-sputtered.

Embodiment 3

A Zn-doped Ge ₂ Sb ₂ Te ₅ phase change memory material having the structural formula: Zn _x (Ge ₂ Sb ₂ Te ₅ ) _1-x , wherein x=15%, which uses Zn, Ge, Sb, Te IV Single element targets are co-sputtered.

Embodiment 4

A Cu-doped GeiSbzTea phase change memory material having the structural formula:

Among them, x=5%, which is formed by sputtering of four kinds of single targets of Cu, Ge, Sb and Te.

Embodiment 5

An Ag-doped Ge ₃ Sb ₄ Te ₈ phase change memory material having the structural formula: Ag _x (Ge ₃ Sb ₄ Te ₈ ) _1-x , wherein x=15%, and its use of Ag, Ge, Sb, Te Four elemental targets are co-sputtered.

Embodiment 6

A Zn-doped Ge ₂ Sb ₂ Te ₄ phase change memory material having the structural formula: Zn _x (Ge ₂ Sb ₂ Te ₄ ) _1-x , wherein x=15%, and 釆, Zn, Ge, Sb, Te Four elemental targets are co-sputtered.

Example 7

A Cu-doped Ge ₃ Sb ₄ Te ₈ phase change memory material having the structural formula: Cu _x (Ge ₃ Sb ₄ Te ₈ ) _1-x , wherein x=10%, and its use of Cu, Ge, Sb, Te Four elemental targets are co-sputtered.

Example eight

An Ag-doped Ge^bzTeA phase change memory material having the structural formula:

Among them, x=10%, which is sputtered by four kinds of single targets of Ag, Ge, Sb and Te.

Example nine A Cu-doped Ge ₂ Sb ₂ Te ₄ phase change memory material having the structural formula: Cu _x (Ge ₂ Sb ₂ Te ₄ )n, wherein x=10%, and the other uses Cu, Ge, Sb, Te The single target is co-sputtered.

Example ten

An Ag-doped Ge ₂ Sb ₂ Te ₄ phase change memory material having the structural formula: Ag _x (Ge ₂ Sb ₂ Te ₄ )n, wherein x=20%, and the latter are four kinds of Ag, Ge, Sb and Te The single target is co-sputtered. The effect embodiment is to strongly support the beneficial effects of the embodiments of the present invention, and provides an effect implementation, for example, to evaluate the performance of the product provided by the embodiment of the present invention.

The phase change memory cell of the Ci GezSbzTes) phase change memory material of the first embodiment of the present invention is subjected to pulse test, and FIG. 4 is a schematic diagram of the test pulse. Among them, the test data is shown in Table 1; the pulse test results are shown in Figure 5.

Table 1

The curves in Figure 5 are from top to bottom: amorphous high resistance state, amorphous low resistance state, and crystallized low resistance state. It can be seen from the figure that the metal-doped Ge-Sb-Te based multi-value storage phase change material provided by the embodiment of the invention has obvious distinction between states and strong controllability of the intermediate state. The metal-doped Ge-Sb-Te based multi-value storage phase change material of the invention has good stability and repeatability by using an intermediate phase change state obtained by forming a conductive path by a metal atom in an amorphous phase change material under an electric field. it is good. Obtaining an intermediate resistance state guide The electric field requires less electric field and lower energy consumption. In addition, the traditional phase change memory cell structure does not improve the process complexity, the programming method is simple, and there is no improvement in circuit design complexity.

Claims

Rights request

A metal-doped Ge-Sb-Te-based multi-value storage phase change material, characterized in that: the memory phase change material has the general formula: M GeaSbbTeJ^, wherein M is a doped metal element, M is at least one of Cu, Ag, and Zn, and X represents a percentage of the number of atoms of M, 0 < x < 20%, and the M is uniformly dispersed in Ge _a Sb _b Te _c .

2. The metal-doped Ge-Sb-Te based multi-value storage phase change material according to claim 1, wherein the phase change material is M _x (Ge ₂ Sb ₂ Te ₅ )^.

3. The metal-doped Ge-Sb-Te based multi-value storage phase change material according to claim 1, wherein the phase change material is

4. The metal-doped Ge-Sb-Te based multi-value storage phase change material according to claim 1, wherein the phase change material is M _x (Ge ₂ Sb ₂ Te _{4 x} .

5. The metal-doped Ge-Sb-Te based multi-value storage phase change material according to claim 1, wherein the phase change material is M _x (Ge ₃ Sb ₄ Te _{8 x} .

6. The metal-doped Ge-Sb-Te based multi-value storage phase change material according to any one of claims 1 to 5, wherein a pulse voltage or a pulse current is applied to the phase change material. The phase change material can be converted between three different states of amorphous high resistance state, amorphous low resistance state and crystalline low resistance state, thereby realizing multi-value storage.

The metal-doped Ge-Sb-Te based multi-value storage phase change material according to any one of claims 1 to 6, wherein a first pulse voltage or a pulse current is applied to the phase change material. The doped metal element M atom can form a conductive path between the two poles to realize a transition from an amorphous high resistance state to an amorphous low resistance state, by applying a second pulse voltage or a pulse current to the phase change material. Crystallization of the phase change material to achieve a transition from an amorphous low resistance state to a crystalline low resistance state, the first pulse voltage or pulse current is small At or equal to 1/2 of the second pulse voltage or pulse current.

8. The metal-doped Ge-Sb-Te based multi-value storage phase change material according to claim 7, wherein said first pulse voltage is 0.25 V-1 V; and said second pulse voltage is 0.5 V-2V.

The metal-doped Ge-Sb-Te based multi-value storage phase change material according to any one of claims 6 to 8, wherein the amorphous high resistance state and the crystalline low resistance state The magnitude of the change in resistance is more than two orders of magnitude.

The metal-doped Ge-Sb-Te-based multi-value storage phase change material according to any one of claims 1 to 9, wherein the phase change material is sputtered by a method of electron beam evaporation. Prepared by vapor deposition or atomic layer deposition.

The metal-doped Ge-Sb-Te based multi-value storage phase change material according to any one of claims 1 to 9, wherein the phase change material is in an inert gas atmosphere, and Ge is used. , Sb, Te, metal M, and four elemental targets are co-sputtered.

The metal-doped Ge-Sb-Te-based multi-value storage phase change material according to any one of claims 1 to 9, wherein the phase change material is in an inert gas atmosphere, and Ge is used. - Sb-Te alloy target, metal M elemental target is co-sputtered.

13. A phase change memory, comprising a phase change memory cell, wherein the phase change memory cell comprises a top electrode, a first isolation layer, a phase change memory material film layer, and a second isolation layer sequentially disposed on a substrate a layer, a lower electrode, the top electrode is in electrical contact with the phase change memory material film layer, and the material of the phase change memory material film layer is the metal doped Ge-Sb according to any one of claims 1-12 -Te based multi-value storage phase change material.

The phase change memory according to claim 13, wherein the phase change memory material thin film layer has a thickness of 10 to 120 nm.