CN114824074A - Phase change material, phase change memory and preparation method - Google Patents

Abstract

The embodiment of the disclosure discloses a phase change material, a phase change memory and a preparation method. The phase change material is applied to a phase change memory; the phase change material includes: a first element and a second element; wherein the loss of the first element is larger than that of the second element in the process of applying the phase-change material to manufacturing the phase-change memory; the composition of a first element in the phase-change material is greater than a preset composition; wherein the first element is larger than the first element of which the part of the preset composition is used for supplementing loss.

Description

Phase change material, phase change memory and preparation method

Technical Field

The disclosed embodiments relate to the field of memories, and relate to, but are not limited to, a phase change material, a phase change memory, and a preparation method.

Background

Phase Change Memory (PCM) is a new type of Memory that uses the large resistance difference between crystalline and amorphous states of a Phase Change material to store information. The phase-change material has higher resistance in an amorphous state, and the molecular structure of the phase-change material is in a disordered state; the phase-change material has lower resistance in a crystalline state, the internal molecular structure of the phase-change material is in an ordered state, and the resistance difference between the two states generally reaches 2 orders of magnitude. Rapid transition of the phase change material between two resistance states (high and low) can be achieved by current-induced joule heating.

The PCM has the advantages of high stability, low power consumption, high storage density, compatibility with a conventional CMOS process, and the like, and thus receives more and more attention from researchers and enterprises. PCM is considered to be one of the most potential next-generation non-volatile memories with its great advantages.

The phase-change material is the core of the PCM, and after the phase-change material is processed into the phase-change memory, the performance of the phase-change material is often deviated from the design performance, so that how to maintain the design performance of the phase-change material after processing becomes a problem to be solved urgently.

Disclosure of Invention

In view of the above, the embodiments of the present disclosure provide a phase change material, a phase change memory, and a method for manufacturing the same.

In a first aspect, the disclosed embodiments provide a phase change material, which is applied to a phase change memory; the phase change material includes:

a first element and a second element; wherein the loss of the first element is larger than that of the second element in the process of applying the phase-change material to manufacturing the phase-change memory;

the composition of a first element in the phase-change material is greater than a preset composition; wherein the first element is larger than the first element of which the part of the preset composition is used for supplementing loss.

In some embodiments, the first element is Ge element; the second element is an Sb element.

In some embodiments, the phase change material further comprises a third element; wherein the third element is at least one of group 3 to group 13 elements in the periodic table.

In some embodiments, the third element comprises an In element.

In some embodiments, the phase change material has a superlattice-like structure.

In some embodiments, the superlattice-like structure includes alternating layers of first and second materials.

In some embodiments, the first layer of material comprises the first element;

the second material layer includes the second element.

In a second aspect, embodiments of the present disclosure provide a method for preparing a phase change material, the method including:

providing a first target material at least containing a first element;

providing a second target material at least containing a second element;

forming a phase change material including a first element and a second element using the first target and the second target; the loss of the first element is larger than that of the second element in the process of applying the phase-change material to manufacturing the phase-change memory; the composition of a first element in the phase-change material is greater than a preset composition; wherein the first element is larger than the first element of which the part of the preset composition is used for supplementing loss.

In some embodiments, the first element is Ge element; the second element is Sb element.

In some embodiments, the phase change material has a superlattice-like structure; the forming of the phase change material including the first element and the second element using the first target and the second target includes:

forming at least one first material layer by using the first target;

and forming second material layers which are alternately arranged with the first material layers by using the second target.

In some embodiments, the phase change material has a superlattice-like structure; the forming a phase change material including a first element and a second element using the first target and the second target includes:

providing a third target material at least containing a third element;

forming at least one first material layer using the first target and/or the third target;

and forming second material layers which are alternately arranged with the first material layers by using the second target and/or the third target.

In some embodiments, the phase change material has a superlattice-like structure; the first target and/or the second target further contain a third element; the forming a phase change material including a first element and a second element using the first target and the second target includes:

forming at least one first material layer by using the first target;

and forming second material layers which are alternately arranged with the first material layers by using the second target.

In some embodiments, the third element is at least one of a group 3 to group 13 element.

In some embodiments, the third element comprises an In element.

In a third aspect, an embodiment of the present disclosure provides a method for manufacturing a phase change memory, where the method includes:

forming a first address line layer;

forming a phase change stack layer on the first address line layer; the phase change stack layer comprises a phase change material layer; the phase change material layer is made of a first phase change material; the first phase change material includes: a first element and a second element; wherein the composition of the first element in the first phase change material is greater than a predetermined composition;

etching the first address line material layer to form a plurality of first address lines which are parallel to each other;

etching the phase change stacked layer to form a plurality of phase change storage stacked bodies which are not connected with each other; wherein material of the phase change material layer in the etched phase change storage stack is converted into a second phase change material; the composition of the first element of the second phase change material is less than the composition of the first element and greater than or equal to the predetermined composition;

forming a plurality of mutually parallel second address lines on the phase change memory stack; the first address line is perpendicular to the second address line.

In some embodiments, the forming a phase change stack layer on the first address line material layer comprises:

and forming a lower electrode layer, an ovonic threshold switch layer, a middle electrode layer, the phase change material layer and an upper electrode layer which are sequentially stacked on the first address line material layer.

In a fourth aspect, an embodiment of the present disclosure provides a phase change memory, including:

a first address line layer; wherein the first address line layer includes a plurality of first address lines parallel to each other;

a second address line layer; wherein the second address line layer includes a plurality of second address lines parallel to each other;

a phase change stack layer between the first address line layer and the second address line layer; the phase change stack layer comprises a phase change material layer; the composition of a first element in the phase-change material when the phase-change material layer is formed is larger than a preset composition; the portion of the first element larger than the predetermined composition is used to supplement the first element lost during the formation of the phase change stack layer.

In some embodiments, the phase change stack layer comprises:

the phase change memory device comprises a lower electrode layer, an bidirectional threshold switch layer, a middle electrode layer, a phase change material layer and an upper electrode layer which are sequentially stacked.

The embodiments of the present disclosure may increase a composition of an element with a higher loss rate (which may be defined as a first element) in a phase change material (which includes at least the first element and a second element), so that the first element may reach a predetermined composition even after being processed and lost, that is, a target performance of the phase change material. And the difference between the initial component and the preset component of the first element is the loss value of the first element in the processing process, so the initial component can be set to be the preset component plus the loss value.

In the embodiment of the disclosure, it is considered that the loss of different elements is different in the process of manufacturing the phase change memory by using the phase change material. Thus, a phase change material that increases the first element component is provided. By means of increasing the components of the first element in the phase change material, the loss of the first element in the subsequent process can be made up when the phase change material is applied to the phase change memory, and therefore consistency of actual performance and design performance of the phase change memory can be kept.

Drawings

Fig. 1 is a perspective view of a three-dimensional cross Point (3D X Point) memory device.

Fig. 2 is a schematic structural diagram of a phase change material provided in an embodiment of the present disclosure;

FIG. 3 is a schematic structural diagram of a phase change material of a superlattice-like structure provided in an embodiment of the disclosure;

FIG. 4 is a flow chart of a method of making a phase change material in an embodiment of the present disclosure;

FIG. 5 is a flow chart of a method for fabricating a phase change memory according to an embodiment of the disclosure;

fig. 6A to 6D are perspective views illustrating a phase change memory according to an embodiment of the disclosure during a manufacturing process;

fig. 7 is a schematic diagram of another phase change memory according to an embodiment of the disclosure.

Detailed Description

To facilitate an understanding of the present disclosure, the present disclosure will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present disclosure are shown in the drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein in the description of the disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The basic storage principle of the phase change memory is that voltage or current pulse signals with different widths and heights are applied to a device unit, so that the phase change material is subjected to physical phase change, namely reversible phase change interconversion between a crystalline state (low resistance state) and an amorphous state (high resistance state), and writing ('1') and erasing ('0') of information are realized. The inter-conversion process includes two processes of amorphous transformation from a crystalline state to an amorphous state, which is called an amorphization process (RESET), and crystalline transformation from an amorphous state to a crystalline state, which is called a crystallization process (SET). The information is then read out by measuring and comparing the difference in resistance between the two physical phases, and this non-destructive reading process ensures accurate reading of the information stored in the device cell.

Phase change memories include two-dimensional phase change memories and three-dimensional phase change memories, including 3D X Point memories, that store data based on a change in resistance of a bulk material property (e.g., in a high resistance state or a low resistance state), in combination with a stackable cross-Point data access array to enable bit addressing. For example, FIG. 1 shows a perspective view of the structure of an exemplary 3D X Point memory 100. According to some embodiments, the 3D X Point memory 100 has a transistor-less cross-Point architecture that locates memory cells at the intersection of vertical conductors; the vertical conductor here includes Word lines (WL, Word Line) and Bit lines (BL, Bit Line) that perpendicularly intersect each other, and the WL and BL are generally constituted by a Line/space (L/S) of a 20nm/20nm constant width formed after a patterning process. A memory cell is formed at the intersection of the vertical WL and BL. The 3D X Point memory 100 includes a plurality of lower bit lines 111 parallel to each other in the same plane and a plurality of upper bit lines 121 parallel to each other in the same plane above the lower bit lines 111.

The 3D X Point memory 100 further includes a plurality of lower word lines 112 and upper word lines 122 parallel to each other in the same plane between the lower bit lines 111 and the upper bit lines 121 in a vertical direction. As shown in fig. 1, each of the lower bit lines 111 and each of the upper bit lines 121 extends laterally in a bit line direction in a top plan view (parallel to a wafer plane), and each of the lower word lines 112 and the upper word lines 122 extends laterally in a word line direction in a top plan view, each of the lower word lines 112 and the upper word lines 122 being perpendicular to each of the lower bit lines 111 and each of the upper bit lines 121.

As shown in fig. 1, the 3D X Point memory 100 includes a plurality of lower memory cells 110 and a plurality of upper memory cells 120, each lower memory cell 110 being disposed at an intersection of a lower bit line 111 and a corresponding lower word line 112, and each upper memory cell 120 being disposed at an intersection of an upper bit line 121 and a corresponding upper word line 122. Each memory cell 110/120 includes at least a vertically stacked PCM element and a selector. Each memory cell 110/120 stores a single bit of data and can be written to or read from each memory cell 110/120 by varying the voltage applied to a corresponding selector (which replaces the need for a transistor). Each memory cell can be individually accessed by applying a current through the top and bottom conductors (e.g., the respective lower 112 or upper 122 word line and lower 111 or upper 121 bit line) that are in contact with each memory cell. The memory cells in the 3D X Point memory 100 are arranged in a memory array. This design of stacking two sets of WL, BL and memory cells improves the bit density.

The performance parameters of the phase change material include the crystal transition temperature (Tx), the Data Retention (Data Retention), and the ratio of the RESET resistance to the Set resistance (ratio of the resistance in the amorphous state to the resistance in the crystalline state). Generally, higher crystallization transition temperatures are beneficial for improved thermal stability and reduced power consumption. Data retention is used to evaluate the probability of phase change materials in the active region of memory cells in an array causing erroneous data and the desired loss of stored data due to undesired transitions under elevated temperature operation. The higher ratio of the RESET resistance to the SET resistance is favorable for distinguishing amorphous state and crystal of the phase-change material, which is favorable for increasing a Read-Write-Modify (RWM) window of the PCM.

In some embodiments, a germanium (Ge), antimony (Sb), and tellurium (Te) -containing composite material (GST), such as Ge, is used in a phase change memory ₂ Sb ₂ Te ₅ The phase change material is used. But the phase-change material is storedLow crystallization transition temperature, poor data retention, and the like. And the elements of the Ge-Sb-Te are affected by processing when the phase-change material is processed (for example, the phase-change material is etched or the phase-change material is cleaned by a wet method), the elements are lost, and the loss speed of the components of the Ge-Sb-Te is different, particularly the loss speed of Ge is larger than that of Sb and Ge. This results in the GST phase change material to be formed into a phase change memory having a final Ge-Sb-Te element composition that is completely different from the initial Ge-Sb-Te element composition after processing. For example with an initial composition of Ge _x Sb _y Te _z Wherein x + y + z is 1. The loss of Ge is a%, the loss of Sb is b% and the loss of Te is c% in the processing process of the GST phase change material, so that the final GST phase change material is Ge _(1-a％)x Sb _(1-b％)y Te _(1-c％)z . Since the performance of the GST Phase Change material is closely related to the composition of each element, the performance of the Phase Change Memory (PCM) manufactured by the method may be deteriorated due to the variation of the performance of different compositions, i.e., the deviation from the original design performance.

In order to solve the above problem, the embodiments of the present disclosure provide a phase change material, as shown in fig. 2, the phase change material 201 is applied to a phase change memory; the phase change material 201 includes:

a first element and a second element; wherein the loss of the first element is larger than that of the second element in the process of applying the phase-change material to manufacturing the phase-change memory;

the composition of a first element in the phase-change material is greater than a preset composition; wherein the first element is larger than the first element of which the part of the preset composition is used for supplementing loss.

PCM may store data using a difference in conductivity exhibited by a phase change material when the phase change material is transformed between its crystalline and amorphous states. When the phase change material is used for manufacturing a phase change memory, the phase change material can be reprocessed and used, and the phase change material can have a specific structure, shape, specification and the like through the reprocessing. And the processing method of the phase-change material may include an etching process, a wet cleaning, and the like.

The phase change material used in the embodiments of the present disclosure includes at least two elements (a first element and a second element), and the loss rates of the elements are different when the phase change material is processed. Here, an element having a higher loss rate may be defined as a first element. For example, when the phase change material is subjected to a dry etching process, a first element in the phase change material is more susceptible to corrosion by an etching gas than a second element, so that the first element is more depleted than the second element.

In some embodiments, the predetermined composition is a composition of the second phase change material. The loss amount of the first element is larger than that of the second element, and the first element can still be ensured to remain in the phase-change material before the second element is completely lost, so that the phase-change material can still keep the design performance.

In some embodiments, the properties of the phase change material are different for different compositions, and the predetermined composition is a composition that can be set to achieve a target property of the phase change material after the first element is depleted. By adding the composition of the first element in the phase change material (the phase change material at least comprises the first element and the second element), the first element can reach the preset composition even after being processed and lost, namely, the target performance of the phase change material is reached. It will be appreciated that the difference between the initial composition and the predetermined composition of the first element is the loss of the first element during processing.

The embodiment of the disclosure considers the intermediate process of phase change memory manufacturing into the design of phase change material parameters, so that the parameter design of the phase change material is more accurate, and the consistency of the actual performance and the design performance of the phase change memory is more favorably maintained.

In some embodiments, the first element is Ge element; the second element is an Sb element.

The phase change material comprises at least two elements, and the two elements can be Ge elements or Sb elements. In addition to these two elements, the phase change material may also include other elements, and the chemical formula of the phase change material may be written as: ge (germanium) oxide _x Sb _y A _z Wherein a may be: te element, Al element, etc., and are not limited herein.

The following is an example of an element A as Te which can be formed into a chemical formula of Ge _x Sb _y Te _z GeSbTe family of phase change materials, Ge _x Sb _y Te _z May be Ge ₃ Sb ₂ Te ₆ 、Ge ₁ Sb ₂ Te ₄ 、Ge ₂ Sb ₂ Te ₅ And Ge ₁ Sb ₄ Te ₇ And so on. The angular subscripts of the chemical formula for a GeSbTe family of materials may represent the composition of the atomic weight of each element thereof. In some embodiments, the chemical formula of GeSbTe family of materials can also be written as Ge _a Sb _b Te _c Wherein a + b + c is 100%. a, b and c represent the proportion of each element in the phase change material.

The GeSbTe family of materials have different properties due to the difference of the subscript of the chemical formula.

In some embodiments, the composition of Ge may be set to a composition that achieves target properties of the phase change material after depletion. Below with Ge ₁ Sb ₂ Te ₄ And Ge ₂ Sb ₂ Te ₅ Comparative analysis was performed for the examples:

Ge ₁ Sb ₂ Te ₄ the carrier concentration of the deposited film and the annealed film of (1) is higher than that of Ge ₂ Sb ₂ Te ₅ Three orders of magnitude greater. Due to Ge ₁ Sb ₂ Te ₄ Having a greater carrier concentration, Ge ₁ Sb ₂ Te ₄ Tends to be specific to Ge ₂ Sb ₂ Te ₅ And is more conductive. The measurement results of resistance and time under isothermal conditions show that Ge ₂ Sb ₂ Te ₅ Specific Ge ₁ Sb ₂ Te ₄ Has thermal stability and is more suitable for data storage.

If directly to Ge ₂ Sb ₂ Te ₅ The processing treatment is carried out, since the loss rate of Ge element is much faster than that of Sb element, there is a possibility that the composition ratio of Ge, Sb and Te is reduced to 1:2:4 at 2:2:5, while Ge element is reduced to 1:2:4 ₁ Sb ₂ Te ₄ Is less than Ge ₂ Sb ₂ Te ₅ I.e. obtained by working the target phase-change materialThe target phase change material, which is undesirable.

In the processing of a GeSbTe family phase change material, the loss of Ge element can be taken into account, and if the loss of Ge is m, Ge can be used _(2+m) Sb ₂ Te ₅ As a phase-change material to be processed, the loss part of Ge after processing is m, and Ge can be obtained ₂ Sb ₂ Te ₅ This target phase change material.

In the above embodiment, only the loss of the Ge element during the processing is considered, and in an embodiment, the loss of the Sb element may be also considered. I.e. using Ge _(2+m) Sb _(2+n) Te ₅ And as the phase-change material to be processed, the part lost by Ge after processing is m, and the part lost by Sb is n. In another embodiment, the loss of Te element can be taken into account, and is not described herein.

In some embodiments, the predetermined composition is a composition of Sb element. Below with Ge ₁ Sb ₂ Te ₄ And Ge ₃ Sb ₂ Te ₆ Comparative analysis after processing was performed as an example:

at Ge ₁ Sb ₂ Te ₄ In the above formula, the atomic weight of Ge element is 1 part, and the atomic weight of Sb element is 2 parts. As the loss speed of Ge element in the processing process is far higher than that of Sb element, Ge element ₁ Sb ₂ Te ₄ It is not preferable that the amount of the Ge element is lost when the amount of the Sb element is lost during the processing.

At Ge ₃ Sb ₂ Te ₆ In the above formula, the atomic weight of Ge element is 3 parts, and the atomic weight of Sb element is 2 parts. Since the loss rate of Ge element during processing is much faster than that of Sb element, Ge element is still 1 part even though the amount of Sb element is lost completely. However, the total loss of Sb is an assumed limit condition, and the loss speed of Sb is far lower than that of Ge element, so the Ge element can be ensured only by making the composition of Ge element larger than that of Sb element _x Sb _y Te _z (x > y) after processing, still GeSbTe familyFamily of materials, still having the properties of GeSbTe family of materials.

The above embodiments are all exemplified by the composition of the GeSbTe family material whose chemical formula has its angular subscripts representing the atomic weight of each element, and it should be understood that when the chemical formula of the GeSbTe family material has its angular subscripts representing the proportion of each element in the phase change material, the chemical formula of the phase change material to be processed may be pushed back according to the loss of each element, and the proportion of each element in the chemical formula of the phase change material to be processed is also 100%.

In some embodiments, the phase change material further comprises a third element; wherein the third element is at least one of group 3 to group 13 elements in the periodic table.

A germanium (Ge), antimony (Sb) and tellurium (Te) -containing composite material (GST), such as Ge, may be used in a phase change memory ₂ Sb ₂ Te ₅ The phase change material is used. However, this material has problems such as low crystal transition temperature and poor data retention.

In some embodiments, the stability of the phase change material in the amorphous state may be improved by adding a third element to the GST to improve long-term data storage performance while maintaining the characteristic that crystallization can be obtained at high speed.

The added third element may be at least one of group 3 to group 13 elements.

In some embodiments, Sn element may be added to GST, the phase-change material may improve the read/write speed of the device to some extent, after Sn element is added, the speed of writing "0" with the phase-change material may be reduced from 200ns to 40ns, and the speed of writing "1" is also reduced from 40ns to 10 ns. In addition, the speed of reading data is improved, and the resistance value of the phase-change material in a crystalline state is reduced from 50K omega m to 4K omega m, so that low power consumption and quick reading and writing are effectively realized.

In some embodiments, the third element comprises an In element.

In some embodiments, the In element may be added to GST to make up the material of the InGeSbTe family. Materials of the InGeSbTe family can be usedGeneral chemical formula In _m (Ge _x Sb _y Te _z ) _(1-m) Where x > y, and in some embodiments, 0.01 < m < 0.2.

The InGeSbTe family material may be In _0.05 (Ge ₃ Sb ₂ Te ₆ ) _0.95 Compared with GST family materials, the phase change material can keep amorphous state under higher temperature environment, so that data can not be lost In the welding process and the crimping process, and the stability and data retention capability of the phase change material In the amorphous state can be improved by adding In, and meanwhile, the characteristic that crystals can be obtained at high speed is kept.

The phase change material in the above embodiments may be a single layer of phase change material.

In some embodiments, the phase change material has a superlattice-like structure.

The phase change material is a material with the thickness of several nanometers, and the material is distributed alternately by different phase change material layers. The optimized design can greatly improve the phase change speed and the structural stability of the phase change layer.

The loss of the phase change material can be limited by forming the quasi-superlattice structure, and the quasi-superlattice structure can be kept through a high-temperature treatment process and a read-write erasing cycle of the phase change memory. Therefore, the phase-change material with the superlattice structure can improve the RESET current (current in the process of amorphization) and circulation of the three-dimensional phase-change memory.

In some embodiments, as shown in fig. 3, the superlattice-like structure includes first material layers 301 and second material layers 302 arranged alternately.

In some embodiments, the first material layer 301 comprises the first element;

the second material layer 302 includes the second element.

The superlattice-like structure at least comprises two or more material layers which are alternately arranged, and the example of the superlattice-like structure comprises two material layers which are alternately arranged is taken as an example. In some embodiments, the first element and the second element may be in different material layers, respectively. Taking the first element as Ge element and the second element as Sb element as an example, the first material layer 301 may include Ge element and the second material layer 302 may include Sb element.

In some embodiments, a first element and/or a third element may be used to form the first material layer 301 and a first element and/or a third element may be used to form the second material layer 302. For example, the first element may be a Ge element, the second element may be a Sb element, and the third element may be an In element. The first phase change material layer 301 may be GeTe, and the second phase change material layer 302 may be In _x (Sb ₂ Te ₃ ) _(1-x) Or the first phase change material layer 301 may be In _x (GeTe) _(1-x) The second phase change material layer 302 may be Sb ₂ Te ₃ . The positions of the first phase-change layer 301 and the second phase-change layer may be interchanged.

In some embodiments, the composition of the In element is between 1% and 20%.

The embodiment of the present disclosure also provides a method for preparing a phase change material, as shown in fig. 4, the method includes:

step S101, providing a first target at least containing a first element;

step S102, providing a second target at least containing a second element;

step S103, forming a phase change material containing a first element and a second element by using the first target and the second target; the loss of the first element is larger than that of the second element in the process of applying the phase-change material to manufacturing the phase-change memory; the composition of a first element in the phase-change material is greater than a preset composition; wherein the first element is larger than the first element of which the part of the preset composition is used for supplementing loss.

The phase-change material can be prepared by a deposition process or a growth process.

Deposition processes include, but are not limited to, Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), Plasma Enhanced Chemical Vapor Deposition (PECVD), Sputtering (Sputtering), Metal Organic Chemical Vapor Deposition (MOCVD), or Atomic Layer Deposition (ALD), among others.

In some embodiments, the first material layer or the second material layer may be formed by an epitaxial growth process, and the second material layer or the first material layer may be formed by a deposition process or a growth process. This step is repeated until the desired phase change material is produced.

In some embodiments, the phase change material of the superlattice-like structure may be formed by a deposition process. For example by means of Sputtering in a deposition process, for example radio frequency Magnetron Sputtering, or atomic layer deposition.

In one embodiment, the phase change material described in the above embodiments may be manufactured by a sputtering system.

The sputtering system can include a chamber, a substrate mounted within the chamber. The substrate may be P-type monocrystalline silicon. A first target material containing at least a first element and a second element may also be provided within the chamber.

The first target material may be prepared in the following manner: firstly, mixing a first element with the component proportion of x and a second element with the component proportion of y to form a raw material. In some embodiments, other elements may also be included, for example, a first element with a composition ratio of x, a second element with a composition ratio of y, and other elements with a composition ratio of z are mixed to form the raw material, and the other elements may be at least one element.

Then, the raw materials are subjected to vacuum melting treatment to obtain a metal compound consisting of the first element, the second element and other elements. And then carrying out powder metallurgy treatment on the metal compound consisting of the first element, the second element and other elements to obtain dry powder consisting of the first element, the second element and other elements.

And finally, carrying out vacuum hot-pressing sintering treatment on the dried powder consisting of the first element, the second element and other elements to obtain the phase-change material sputtering target consisting of the first element, the second element and other elements.

And forming the phase-change material containing the first element and the second element by using the phase-change material sputtering target consisting of the first element, the second element and other elements through a sputtering process. The loss of the first element in the process of applying the phase-change material to manufacturing the phase-change memory is larger than that of the second element, so that the composition x of the first element in the phase-change material is larger than the preset composition x 1. Wherein the first element is larger than the first element used to supplement the loss of the portion of the predetermined composition. I.e., the loss of the first element is x-x 1.

The phase change material is sputtered by increasing the composition of the first element in the sputtering target material. The composition ratio of the first element in the phase change material is also x. The loss of the first element in the subsequent process of applying the phase change material to the manufacturing of the phase change memory is x-x1, and finally the composition of the first element in the phase change material is x1, namely the composition is a preset composition, and meanwhile, the phase change material also has preset performance. In some embodiments, the predetermined composition may be a composition of the first element at a target property of the phase change material; in some embodiments, the predetermined composition may be a composition of the second element.

In some embodiments, the first element is Ge element; the second element is an Sb element.

In some embodiments, the first element is Ge element, the second element is Sb element, and other elements include, but are not limited to, Al element, Sn element, Te element, and the like.

The sputtering target can be Ge _x Sb _y 、Ge _x Sb _y A _z And so on. The angular subscripts of the formula may represent the components whose elements occupy atomic weight and x is greater than a predetermined component x 1.

In some embodiments, the phase change material has a superlattice-like structure; the forming of the phase change material including the first element and the second element using the first target and the second target includes:

forming at least one first material layer by using the first target;

and forming second material layers which are alternately arranged with the first material layers by using the second target.

In some embodiments, at least two targets may also be used to form a phase change material of a superlattice-like structure.

In some embodiments, the first target may contain a first element and the second target may contain a second element. By using a sputtering process, a first material layer is formed on the substrate by sputtering using a first target, so that the first material layer contains a first element, and then a second material layer is formed by sputtering using a second target, so that the second material layer contains a second element. The first material layer and the second material layer may constitute a composite layer. N composite layers, for example 4 layers, may be formed. The phase change material with a superlattice-like structure is formed by combining 4 layers of the first material layer and the second material layer to form a composite layer.

In some embodiments, the phase change material has a superlattice-like structure; the forming a phase change material including a first element and a second element using the first target and the second target includes:

providing a third target material at least containing a third element;

forming at least one first material layer using the first target and/or the third target;

and forming second material layers which are alternately arranged with the first material layers by using the second target and/or the third target.

In some embodiments, the superlattice-like structure phase change material may also have a third element. Three targets may be used to form the phase change material. For example, a third target containing at least a third element may also be provided in the chamber.

By utilizing a sputtering process, a first material layer is firstly formed on the substrate by utilizing a first target and/or a third target through co-sputtering, so that the first material layer contains a first element and/or a third element, and then a second material layer is formed by utilizing a second target and/or a third target through sputtering, so that the second material layer contains a second element and/or a third element. The first material layer and the second material layer may constitute a composite layer. N composite layers, for example 4 layers, may be formed. The phase change material with a superlattice-like structure is formed by combining 4 layers of the first material layer and the second material layer to form a composite layer.

In some embodiments, the phase change material has a superlattice-like structure; the first target and/or the second target further contain a third element; the forming a phase change material including a first element and a second element using the first target and the second target includes:

forming at least one first material layer by using the first target;

and forming second material layers which are alternately arranged with the first material layers by using the second target.

In some embodiments, the superlattice-like structure phase change material may also have a third element. Two targets may be used to form the phase change material.

The method comprises the steps of firstly forming a first material layer on a substrate by sputtering through a first target by using a sputtering process, wherein the first target can contain a first element and/or a third element, so that the first material layer contains the first element and/or the third element, and then forming a second material layer by sputtering through a second target, wherein the second target can contain a second element and/or a third element, so that the second material layer contains the second element and/or the third element. The first material layer and the second material layer may constitute a composite layer. N composite layers, for example 4 layers, may be formed. The phase change material with a superlattice-like structure is formed by combining 4 layers of the first material layer and the second material layer to form a composite layer.

In some embodiments, the third element is at least one of a group 3 to group 13 element.

In some embodiments, the third element comprises an In element.

In some embodiments, the first element may be a Ge element, the second element may be a Sb element, and the third element may be an In element. The first phase change material layer may be GeTe and the second phase change material layer may be In _x (Sb ₂ Te ₃ ) _(1-x) Or the first phase change material layer may be In _x (GeTe) _(1-x) The second phase change material layer may be Sb ₂ Te ₃ . In some embodiments, 1%<x<20％。

The embodiment of the present disclosure further provides a method for manufacturing a phase change memory, as shown in fig. 5, the method includes:

step S201, forming a first address line layer;

step S202, forming a phase change stacking layer on the first address line layer; the phase change stack layer comprises a first phase change material layer; the material of the first phase change material layer is a first phase change material; the first phase change material includes: a first element and a second element; wherein the composition of the first element in the first phase change material is greater than a predetermined composition;

step S203, etching the first address line material layer to form a plurality of first address lines which are parallel to each other;

step S204, etching the phase change stacking layer to form a plurality of phase change storage stacking bodies which are not connected with each other; wherein the first phase change material in the etched first phase change material layer in the phase change storage stack is converted into a second phase change material; the composition of the first element of the second phase change material is smaller than that of the first element in the first phase change material and is larger than or equal to the preset composition;

step S205, forming a plurality of second address lines which are parallel to each other on the phase change storage stacked body; the first address line is perpendicular to the second address line.

In an actual process, as shown in fig. 6A, the substrate 300 may be first provided, and the first address line layer 411 may be formed on the substrate 300 using a deposition process or a growth process. The substrate 300 is used to provide support. Here, the substrate 300 may be a semiconductor substrate, which may include a P-type semiconductor material substrate, such as a silicon (Si) substrate or a germanium (Ge) substrate, etc., an N-type semiconductor substrate, such as an indium phosphide (InP) substrate, a composite semiconductor material substrate, such as a silicon germanium (SiGe) substrate, etc., a silicon-on-insulator (SOI) substrate, a germanium-on-insulator (GeOI) substrate, etc. In addition, the substrate 300 in the embodiment of the present disclosure may also be a substrate in which a part of a device structure is already formed, or a substrate having some wirings, which is not limited herein.

The material of the first address line layer 411 may include a conductive material including, but not limited to, tungsten (W), cobalt (Co), copper (Cu), aluminum (Al), polysilicon, doped silicon, silicide, or any combination thereof. The materials of the other address line layers (e.g., the second address line layer) involved in subsequent process steps may be selected from the materials described above.

The phase change stack layer 410 is formed on the first address line layer 411 by a deposition process or a growth process.

The first address line layer 411 and the phase change stack layer 410 are etched in a second direction shown in fig. 6A. Specifically, a mask may be formed on the phase change memory stack layer 410, and the mask may be patterned by exposure and development. The phase change memory stack layer 410 and the first address line layer 411 are etched based on the patterned hard mask. Resulting in a plurality of phase change memory stack stripes 410a and a plurality of first address lines 411a as shown in fig. 6B. The etching method includes, but is not limited to, dry etching and wet etching.

A second address line layer 422 as shown in fig. 6C is formed on the plurality of phase change memory stack stripes 410a using a deposition process or a growth process.

The second address line layer 422 and the plurality of phase change stack stripes 410a are etched in a first direction as shown in fig. 6C. Specifically, a mask may be formed on the second address line layer 422, and the mask may be patterned by exposure and development. The second address line layer 422 and the plurality of phase change stack stripes 410a are etched in a first direction based on a patterned hard mask. Resulting in a plurality of phase change memory stacks 410b and at least one second address line 422a as shown in figure 6D. The etching method includes, but is not limited to, dry etching and wet etching.

The first address line 411a may function as a word line or a bit line, and the second address line 422a may also function as a word line or a bit line. In some embodiments, the first address line 411a may be a bit line and the second address line 422a may be a word line.

In some embodiments, as shown in fig. 6A, the forming the phase change stack layer 410 on the first address line material layer 411 includes:

a first lower electrode layer 401, a first bi-directional threshold switch layer 402, a first intermediate electrode layer 403, the first phase change material layer 404, and a first upper electrode layer 405 are formed on the first address line material layer 410, which are sequentially stacked.

The phase change memory stack layer 410 may include a first phase change material layer 404, a first bidirectional threshold switch layer 402, and a plurality of electrode material layers stacked. Specifically, as shown in fig. 6A, for example, a first lower electrode layer 401, a first bidirectional threshold switching layer 402, a first intermediate electrode layer 403, a first phase change material layer 404, and a first upper electrode layer 405 are included, which are stacked in this order. Here, each of the first upper electrode layer 405, the first lower electrode layer 401, and the first middle electrode layer 403 may include a conductive material including, but not limited to, W, Co, Cu, Al, carbon, polysilicon, doped silicon, silicide, or any combination thereof. In some embodiments, the locations of the ovonic threshold switch layer 402 and the phase change material layer 404 may be interchanged.

In some embodiments, each of the first upper electrode layer 405, the first lower electrode layer 401, and the first middle electrode layer 403 includes carbon, such as amorphous carbon (a-c), carbon nanotubes, or graphene. The material of the first bi-directional threshold switching layer 402 may include chalcogenide materials such as ZnxTey, GexTey, NbxOy, or SixAsyTez, among others. The phase change material of the first phase change material layer 404 is a first phase change material including: a first element and a second element; wherein the loss of the first element is greater than that of the second element in the process of applying the first phase change material to manufacturing the phase change memory. The composition of a first element in the first phase change material is greater than a preset composition; wherein the first element is larger than the first element of which the part of the preset composition is used for supplementing loss. The first phase change material layer forms the second phase change material layer 404a in the phase change storage stack 410b after a processing process (e.g., an etching process, a cleaning process), and the composition of the first element in the third phase change material layer 404b is a predetermined composition. The composition of the first element in the phase change memory stack 410b is a predetermined composition, i.e., has a predetermined property.

In some embodiments, the predetermined composition may be a composition of a second element; in some embodiments, the predetermined composition may be a composition of the first element at a target property of the phase change material.

The structure, configuration, and materials of the phase change storage stack layer 410 and the phase change storage stack 410b formed after etching are not limited thereto and may include any suitable structure, configuration, and materials.

Fig. 7 is an example of an array of phase change memory cells, which includes a plurality of phase change memory cells 500, each having a first conductive line 501 above and a second conductive line 509 below. Wherein each phase change memory cell 500 comprises: an upper electrode 502, a phase change material 504, a first conductive layer 503 and a second conductive layer 505 on the upper and lower sides of the phase change material 504, a middle electrode 506, an ovonic threshold switch 507, and a lower electrode 508. The left and right sidewalls of the phase change material 504 also include a liner layer 510, a first dielectric layer 511, and a sidewall layer 512.

The material of the first conductive line 501 and the material of the second conductive line 509 may comprise conductive materials including, but not limited to, tungsten (W), cobalt (Co), copper (Cu), aluminum (Al), polysilicon, doped silicon, silicide, or any combination thereof.

The first conductive line 501 may act as a bit line or a word line; the second conductive line 509 may also function as a word line or a bit line. For example, when the first conductive line 501 functions as a bit line, the second conductive line 509 may function as a word line. The phase change memory cell is used for storing data by performing phase change based on a voltage difference between the first conductive line and the second conductive line.

The materials of the upper electrode 502, the middle electrode 506, and the lower electrode 508 include carbon-containing materials including, but not limited to, amorphous carbon (a-c), carbon nanotubes, or graphene, among others.

The first conductive layer 503 and the second conductive layer 505 may be used to improve the contact sensitivity of the phase change material 504 with the upper electrode 502 and the middle electrode 506. In some embodiments, the first conductive layer 503 and the second conductive layer 505 may not be used.

The material of the ovonic threshold switch 507 may comprise a chalcogenide material, which may be, for example, Ge-Se, Si-Te, C-Te, B-Te, Ge-Te, Al-Te, Ge-Sb, Bi-Te, As-Te, Sn-Te, Ge-Te-Pb, or Ge-Se-Te, and the like.

The phase change material described in the embodiments of the present disclosure may be processed to obtain the material of the phase change material 504, and the phase change material described in the embodiments of the present disclosure includes a first element and a second element; wherein the loss of the first element is larger than that of the second element in the process of applying the phase-change material to manufacturing the phase-change memory; the composition of a first element in the phase-change material is greater than a preset composition; wherein the first element is larger than the first element of which the part of the preset composition is used for supplementing loss.

Each phase change memory cell 500 further includes a first Gap filling layer (Gap Fill)514 therebetween, and sidewalls of the phase change memory cell array further include a second Gap filling layer 513 and a second dielectric layer 515. Examples of the gap filling material used for the gap filling layer include, but are not limited to, gallium arsenide (GaAs), indium gallium arsenide (InGaAs), gallium nitride (GaN), aluminum nitride (AlN), cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium tellurite (CdTe), zinc sulfide (ZnS), lead sulfide (PbS), and lead selenide (PbSe), and cobalt-based compounds, and any combination thereof.

The first gap filling layer 514 and the second gap filling layer 513 may be made of the same material or different materials.

The material of the second dielectric layer 515 may be an oxide. The material of the first dielectric layer 511 may be the same as that of the second dielectric layer 515 or may be different.

In some embodiments, the positions of the phase change material 504 and the ovonic threshold switch 507 may be interchanged.

The phase change memory cell array and the peripheral circuit may constitute a phase change memory.

An embodiment of the present disclosure further provides a phase change memory, including:

a first address line layer; wherein the first address line layer includes a plurality of first address lines parallel to each other;

a second address line layer; wherein the second address line layer includes a plurality of second address lines parallel to each other;

a phase change stack layer between the first address line layer and the second address line layer; the phase change stack layer comprises a phase change material layer; the composition of a first element in the phase-change material when the phase-change material layer is formed is larger than a preset composition; the portion of the first element larger than the predetermined composition is used to supplement the first element lost during the formation of the phase change stack layer.

In some embodiments, the phase change stack layer comprises:

the phase change memory device comprises a lower electrode layer, an ovonic threshold switch layer, a middle electrode layer, a phase change material layer and an upper electrode layer which are sequentially stacked.

The phase-change material provided by the embodiment of the disclosure has better thermal stability, faster SET speed, lower RESET current and high endurance cycle compared with the phase-change material before improvement.

It should be appreciated that reference throughout this specification to "some embodiments," "one embodiment," or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. It should be understood that, in various embodiments of the present disclosure, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure. The above-mentioned serial numbers of the embodiments of the present disclosure are merely for description and do not represent the merits of the embodiments.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above description is only an embodiment of the present disclosure, but the scope of the present disclosure is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present disclosure, and all the changes or substitutions should be covered by the scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims (18)

1. The phase change material is characterized in that the phase change material is applied to a phase change memory; the phase change material includes:

a first element and a second element; wherein the loss of the first element is larger than that of the second element in the process of applying the phase-change material to manufacturing the phase-change memory;

the composition of a first element in the phase-change material is greater than a preset composition; wherein the first element is larger than the first element of which the part of the preset composition is used for supplementing loss.

2. The phase-change material according to claim 1, wherein the first element is a Ge element; the second element is an Sb element.

3. The phase change material as claimed in claim 1, further comprising a third element; wherein the third element is at least one of group 3 to group 13 elements in the periodic table.

4. The phase change material of claim 3, wherein the third element comprises an In element.

5. The phase change material of claim 1, wherein the phase change material has a superlattice-like structure.

6. The phase change material of claim 5, wherein the superlattice-like structure comprises alternating layers of the first material and the second material.

7. The phase change material of claim 6, wherein the first material layer comprises the first element;

the second material layer includes the second element.

8. A method of making a phase change material, the method comprising:

providing a first target material at least containing a first element;

providing a second target material at least containing a second element;

forming a phase change material including a first element and a second element using the first target and the second target; the loss of the first element is larger than that of the second element in the process of applying the phase-change material to manufacturing the phase-change memory; the composition of a first element in the phase-change material is greater than a preset composition; wherein the first element is larger than the first element of which the part of the preset composition is used for supplementing loss.

9. The method according to claim 8, wherein the first element is a Ge element; the second element is an Sb element.

10. The method of claim 8, wherein the phase change material has a superlattice-like structure; the forming of the phase change material including the first element and the second element using the first target and the second target includes:

forming at least one first material layer by using the first target;

and forming second material layers which are alternately arranged with the first material layers by using the second target.

11. The method of claim 8, wherein the phase change material has a superlattice-like structure; the forming a phase change material including a first element and a second element using the first target and the second target includes:

providing a third target material at least containing a third element;

forming at least one first material layer using the first target and/or the third target;

and forming second material layers which are alternately arranged with the first material layers by using the second target and/or the third target.

12. The method of claim 8, wherein the phase change material has a superlattice-like structure; the first target and/or the second target further contain a third element; the forming a phase change material including a first element and a second element using the first target and the second target includes:

forming at least one first material layer by using the first target;

and forming second material layers which are alternately arranged with the first material layers by using the second target.

13. The method of claim 11 or 12, wherein the third element is at least one of group 3 to group 13 elements.

14. The method for preparing a phase change material according to claim 13,

the third element includes an In element.

15. A method for manufacturing a phase change memory, the method comprising:

forming a first address line layer;

forming a phase change stack layer on the first address line layer; the phase change stack layer comprises a phase change material layer; the phase change material layer is made of a first phase change material; the first phase change material includes: a first element and a second element; wherein the composition of the first element in the first phase change material is greater than a predetermined composition;

etching the first address line material layer to form a plurality of first address lines which are parallel to each other;

etching the phase change stacked layer to form a plurality of phase change storage stacked bodies which are not connected with each other; wherein material of the phase change material layer in the etched phase change storage stack is converted into a second phase change material; the composition of the first element of the second phase change material is less than the composition of the first element and greater than or equal to the predetermined composition;

forming a plurality of second address lines parallel to each other on the phase change memory stack; the first address line is perpendicular to the second address line.

16. The method of claim 15, wherein forming the phase change stack layer on the first address line material layer comprises:

and forming a lower electrode layer, an ovonic threshold switch layer, a middle electrode layer, the phase-change material layer and an upper electrode layer which are sequentially stacked on the first address line material layer.

17. A phase change memory, comprising:

a first address line layer; wherein the first address line layer includes a plurality of first address lines parallel to each other;

a second address line layer; wherein the second address line layer includes a plurality of second address lines parallel to each other;

a phase change stack layer between the first address line layer and the second address line layer; the phase change stack layer comprises a phase change material layer; the composition of a first element in the phase-change material when the phase-change material layer is formed is larger than a preset composition; the portion of the first element larger than the predetermined composition is used to supplement the first element lost during the formation of the phase change stack layer.

18. The phase change memory of claim 17, wherein the phase change stack layer comprises:

the phase change memory device comprises a lower electrode layer, an bidirectional threshold switch layer, a middle electrode layer, a phase change material layer and an upper electrode layer which are sequentially stacked.

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