Phase change material, phase change memory, and preparation method

Abstract

The disclosed embodiment discloses a phase change material, a phase change memory, and a preparation method. The phase change material is applied to the phase change memory; the phase change material comprises: a first element and a second element; wherein, in the process of applying the phase change material to manufacture the phase change memory, the loss of the first element is greater than the second element; the component of the first element in the phase change material is greater than a preset component; wherein, the portion of the first element greater than the preset component is used to supplement the loss of the first element.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the field of memory, and are related to but not limited to a phase change material, a phase change memory, and a preparation method. Background Art

[0002] Phase Change Memory (PCM) is a new type of memory that uses the huge resistance difference between the crystalline and amorphous states of phase change materials to achieve information storage. Phase change materials have higher resistance in the amorphous state, and their molecular structure is in a disordered state; phase change materials have lower resistance in the crystalline state, and their internal molecular structure is in an ordered state. The resistance difference between the two states usually reaches 2 orders of magnitude. The Joule heat induced by current can achieve a rapid transition between the two resistance states (high resistance and low resistance) of the phase change material.

[0003] PCM has attracted more and more attention from researchers and enterprises due to its advantages such as strong stability, low power consumption, high storage density, and compatibility with traditional CMOS processes. With its huge advantages, PCM is considered to be one of the most promising next-generation non-volatile memories.

[0004] Phase change material is the core of PCM. After being processed into phase change memory, its performance often deviates from the designed performance. How to make the phase change material maintain its designed performance after processing has become an urgent problem to be solved. Summary of the invention

[0005] In view of this, embodiments of the present disclosure provide a phase change material, a phase change memory, and a preparation method.

[0006] In a first aspect, an embodiment of the present disclosure provides a phase change material, wherein the phase change material is applied to a phase change memory; the phase change material comprises:

[0007] A first element and a second element; wherein, in the process of applying the phase change material to manufacture a phase change memory, the loss of the first element is greater than that of the second element;

[0008] The composition of the first element in the phase change material is greater than a preset composition; wherein the portion of the first element that is greater than the preset composition is used to supplement the lost first element.

[0009] In some embodiments, the first element is Ge; and the second element is Sb.

[0010] In some embodiments, the phase change material further includes a third element; wherein the third element is at least one of the elements from Group 3 to Group 13 in the periodic table.

[0011] In some embodiments, the third element includes an In element.

[0012] In some embodiments, the phase change material has a superlattice-like structure.

[0013] In some embodiments, the superlattice-like structure includes first material layers and second material layers that are alternately arranged.

[0014] In some embodiments, the first material layer includes the first element;

[0015] The second material layer includes the second element.

[0016] In a second aspect, an embodiment of the present disclosure provides a method for preparing a phase change material, the method comprising:

[0017] providing a first target material containing at least a first element;

[0018] providing a second target material containing at least a second element;

[0019] A phase change material comprising a first element and a second element is formed using the first target material and the second target material; during the process of using the phase change material in manufacturing a phase change memory, the loss of the first element is greater than the second element; the composition of the first element in the phase change material is greater than a preset composition; wherein the portion of the first element that is greater than the preset composition is used to supplement the lost first element.

[0020] In some embodiments, the first element is Ge; and the second element is Sb.

[0021] In some embodiments, the phase change material has a superlattice-like structure; and forming the phase change material containing the first element and the second element by using the first target material and the second target material comprises:

[0022] forming at least one first material layer using the first target material;

[0023] The second target material is used to form a second material layer arranged alternately with the first material layer.

[0024] In some embodiments, the phase change material has a superlattice-like structure; and forming the phase change material containing the first element and the second element by using the first target material and the second target material comprises:

[0025] providing a third target material containing at least a third element;

[0026] Using the first target material and / or the third target material to form at least one first material layer;

[0027] The second target material and / or the third target material are used to form a second material layer arranged alternately with the first material layer.

[0028] In some embodiments, the phase change material has a superlattice-like structure; the first target material and / or the second target material further contains a third element; and the forming of the phase change material containing the first element and the second element by using the first target material and the second target material comprises:

[0029] forming at least one first material layer using the first target material;

[0030] The second target material is used to form a second material layer arranged alternately with the first material layer.

[0031] In some embodiments, the third element is at least one of Group 3 to Group 13 elements.

[0032] In some embodiments, the third element includes an In element.

[0033] In a third aspect, an embodiment of the present disclosure provides a method for preparing a phase change memory, the method comprising:

[0034] forming a first address line layer;

[0035] A phase change stacking layer is formed on the first address line layer; the phase change stacking layer comprises a phase change material layer; the material of the phase change material layer is a first phase change material; the first phase change material comprises: a first element and a second element; wherein the component of the first element in the first phase change material is greater than a preset component;

[0036] Etching the first address line material layer to form a plurality of first address lines parallel to each other;

[0037] Etching the phase change stacking layer to form a plurality of mutually unconnected phase change memory stacking bodies; wherein the material of the phase change material layer in the etched phase change memory stacking body 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 preset composition;

[0038] A plurality of second address lines parallel to each other are formed on the phase-change memory stack; the first address lines are perpendicular to the second address lines.

[0039] In some embodiments, forming a phase change stack layer on the first address line material layer includes:

[0040] A lower electrode layer, a bidirectional threshold switch layer, an intermediate electrode layer, the phase change material layer and an upper electrode layer are sequentially stacked on the first address line material layer.

[0041] In a fourth aspect, an embodiment of the present disclosure provides a phase change memory, including:

[0042] A first address line layer; wherein the first address line layer includes a plurality of first address lines parallel to each other;

[0043] A second address line layer; wherein the second address line layer includes a plurality of second address lines parallel to each other;

[0044] A phase change stacking layer located between the first address line layer and the second address line layer; the phase change stacking layer comprises a phase change material layer; wherein the composition of a first element in the phase change material of the phase change material layer when formed is greater than a preset composition; a portion of the first element greater than the preset composition is used to supplement the first element lost in the process of forming the phase change stacking layer.

[0045] In some embodiments, the phase change stack layer comprises:

[0046] A lower electrode layer, a bidirectional threshold switch layer, an intermediate electrode layer, the phase change material layer and an upper electrode layer are stacked in sequence.

[0047] In the embodiment of the present disclosure, by adding a component of an element with a higher loss rate in a phase change material (the phase change material includes at least a first element and a second element) (the element with a higher loss rate can be defined as the first element), the first element can reach a preset component even after being lost during processing, that is, the target performance of the phase change material is achieved. And the difference between the initial component of the first element and the preset component is the loss value of the first element during processing, so the initial component can be set to the preset component plus the loss value.

[0048] In the embodiments of the present disclosure, it is taken into account that in the process of manufacturing a phase change memory using a phase change material, the losses of different elements are different. Therefore, a phase change material with an increased first element component is provided. By increasing the component of the first element in the phase change material, the phase change material can compensate for the loss of the first element in the subsequent process when applied to the phase change memory, thereby being more conducive to maintaining the consistency between the actual performance of the phase change memory and the designed performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A perspective view of a 3D X Point memory device.

[0050] Figure 2 A schematic diagram of the structure of a phase change material provided in an embodiment of the present disclosure;

[0051] Figure 3 A schematic structural diagram of a phase change material having a superlattice structure provided in an embodiment of the present disclosure;

[0052] Figure 4 is a flow chart of a method for preparing a phase change material in an embodiment of the present disclosure;

[0053] Figure 5 is a flow chart of a method for preparing a phase change memory in an embodiment of the present disclosure;

[0054] Figures 6A to 6D A structural perspective view of a phase change memory during preparation provided by an embodiment of the present disclosure;

[0055] Figure 7 A schematic diagram of another phase change memory provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0056] In order to facilitate understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are shown in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thorough and comprehensive.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0058] The basic storage principle of phase change memory is to apply voltage or current pulse signals of different widths and heights to the device unit to cause the physical phase of the phase change material to change, that is, a reversible phase change occurs between the crystalline state (low resistance state) and the amorphous state (high resistance state), thereby realizing the writing ("1") and erasing ("0") operations of information. The mutual conversion process includes two processes: the amorphization transition from the crystalline state to the amorphous state and the crystallization transition from the amorphous state to the crystalline state. The former is called the amorphization process (RESET) and the latter is called the crystallization process (SET). The information is then read out by measuring and comparing the resistance difference between the two physical phases. This non-destructive reading process can ensure that the information stored in the device unit is accurately read out.

[0059] Phase change memory includes two-dimensional phase change memory and three-dimensional phase change memory, and three-dimensional phase change memory includes 3D XPoint memory, which stores data based on the resistance change of bulk material properties (e.g., in a high resistance state or a low resistance state), and this scheme is combined with a stackable cross-point data access array to enable bit addressing. For example, Figure 1A perspective view of the structure of an exemplary 3D X Point memory 100 is shown. According to some embodiments, the 3D X Point memory 100 has a transistor-free cross-point architecture, which enables memory cells to be located at the intersection of vertical conductors; the vertical conductors here include word lines (WL) and bit lines (BL) that intersect each other perpendicularly, and the WL and BL are generally composed of 20nm / 20nm line width (line / space, L / S) formed after a patterning process. Memory cells are formed at the intersections of the vertical WL and BL. The 3D X Point memory 100 includes a plurality of lower bit lines 111 that are parallel to each other in the same plane and a plurality of upper bit lines 121 that are parallel to each other in the same plane above the lower bit lines 111.

[0060] The 3D X Point memory 100 further includes a plurality of lower word lines 112 and upper word lines 122 that are parallel to each other in the same plane between the lower word lines 111 and the upper word lines 121 in the vertical direction. Figure 1 As shown, each lower bit line 111 and each upper bit line 121 extend laterally along the bit line direction in a top plan view (parallel to the wafer plane), and each lower word line 112 and each upper word line 122 extend laterally along the word line direction in a top plan view, and each lower word line 112 and each upper word line 122 are perpendicular to each lower bit line 111 and each upper bit line 121.

[0061] like Figure 1 As shown, the 3D X Point memory 100 includes a plurality of lower memory cells 110 and a plurality of upper memory cells 120, each of the lower memory cells 110 being disposed at the intersection of a lower bit line 111 and a corresponding lower word line 112, and each of the upper memory cells 120 being disposed at the 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 data bit, and each memory cell 110 / 120 can be written or read by changing a 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 a top conductor and a bottom conductor (e.g., a corresponding lower word line 112 or upper word line 122 and a lower bit line 111 or upper bit line 121) 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 groups of WL, BL and storage units improves the bit density.

[0062] The performance parameters of phase change materials include crystal transition temperature (Tx), data retention performance (Data Retention), and the ratio of RESET resistance to Set resistance (the ratio of resistance in amorphous state to resistance in crystalline state). Generally, a higher crystal transition temperature is beneficial to improving thermal stability and reducing power consumption. Data retention capability is used to evaluate the probability of generating erroneous data and loss of required stored data due to unexpected conversion of phase change materials in the active area of ​​a memory cell in an array under operation with elevated temperature. A higher ratio of RESET resistance to SET resistance is beneficial to distinguishing the amorphous and crystalline phase change materials, which is beneficial to increase the PCM Read-Write-Modify (RWM) window.

[0063] In some embodiments, a synthetic material (GST) containing germanium (Ge), antimony (Sb) and tellurium (Te), such as Ge2Sb2Te5, is used as a phase change material in a phase change memory. However, the phase change material has problems such as low crystallization transition temperature and poor data retention performance. In addition, when the phase change material is processed (for example, etching or wet cleaning of the phase change material), the Ge-Sb-Te elements are affected by the processing, and each element will be lost, and the loss rate of each Ge-Sb-Te component is different, especially Ge, which has a greater loss rate than Sb and Ge. This will cause the GST phase change material to form a phase change memory, after being processed, the final Ge-Sb-Te element components are completely different from the initial Ge-Sb-Te element components. For example, the initial component is Ge x Sb y Te z , where x+y+z=1. During the processing of the GST phase change material, the loss of Ge is a%, the loss of Sb is b%, and the loss of Te is c%. Therefore, the final GST phase change material is Ge (1-a％)x Sb (1-b％)y Te (1-c％)z Since the performance of GST phase change materials is closely related to the composition of each element, its performance will change under different compositions, that is, it will deviate from the original design performance, so the performance of the manufactured phase change memory (PCM) will deteriorate.

[0064] To solve the above problems, the present disclosure provides a phase change material, such as Figure 2 As shown, the phase change material 201 is applied to a phase change memory; the phase change material 201 includes:

[0065] A first element and a second element; wherein, in the process of applying the phase change material to manufacture a phase change memory, the loss of the first element is greater than that of the second element;

[0066] The composition of the first element in the phase change material is greater than a preset composition; wherein the portion of the first element that is greater than the preset composition is used to supplement the lost first element.

[0067] PCM can store data by utilizing the difference in conductivity of phase change materials when they transform between their crystalline and amorphous states. When phase change materials are used to manufacture phase change memory, they can be reprocessed before use. Through reprocessing, the phase change materials can have specific structures, shapes, specifications, etc. The methods for processing phase change materials can include etching processes, wet cleaning, etc.

[0068] The phase change material used in the embodiment of the present disclosure contains at least two elements (a first element and a second element), and the loss rate of each element is different when the phase change material is processed. Here, the element with a faster loss rate can be defined as the first element. For example, when the phase change material is dry-etched, the first element in the phase change material is more susceptible to corrosion by the etching gas than the second element, resulting in more loss of the first element than the second element.

[0069] In some embodiments, the preset component is a component of the second phase change material. The loss of the first element is greater than the loss of the second element. Before the second element is completely lost, the first element can still be guaranteed to remain in the phase change material, so that the phase change material can still maintain its designed performance.

[0070] In some embodiments, the performance of the phase change material is different under different components, and the preset component can be set as a component that can achieve the target performance of the phase change material after the loss of the first element. By increasing the component of the first element in the phase change material (the phase change material contains at least the first element and the second element), the first element can reach the preset component even after being lost during processing, that is, the target performance of the phase change material is achieved. It can be understood that the difference between the initial component of the first element and the preset component is the loss value of the first element during processing.

[0071] The disclosed embodiment takes the intermediate process of phase change memory manufacturing into consideration in the design of phase change material parameters, making the parameter design of the phase change material more accurate and more conducive to maintaining the consistency between the actual performance and the designed performance of the phase change memory.

[0072] In some embodiments, the first element is Ge; and the second element is Sb.

[0073] The phase change material contains at least two elements, which can be Ge or Sb. In addition to these two elements, the phase change material can also include other elements. The chemical formula of the phase change material can be written as: Ge x Sb y Az , wherein A can be: Te element, Al element, etc., which is not limited here.

[0074] Taking element A as Te as an example, the chemical formula can be Ge x Sb y Te z The GeSbTe family of phase change materials, Ge x Sb y Te z It can be Ge3Sb2Te6, Ge1Sb2Te4, Ge2Sb2Te5, Ge1Sb4Te7, etc. The angular subscripts of the chemical formula of the GeSbTe family material can represent the atomic weight of each element. In some embodiments, the chemical formula of the GeSbTe family material can also be written as Ge a Sb b Te c , where a+b+c=100%. a, b, c represent the proportion of each element in the phase change material.

[0075] The materials in the GeSbTe family have different properties due to the different angular subscripts in the chemical formula.

[0076] In some embodiments, the composition of Ge can be set to a composition that can achieve the target performance of the phase change material after loss. The following is a comparative analysis using Ge1Sb2Te4 and Ge2Sb2Te5 as examples:

[0077] The carrier concentration of both the deposited and annealed films of Ge1Sb2Te4 is three orders of magnitude greater than that of Ge2Sb2Te5. Due to its larger carrier concentration, Ge1Sb2Te4 tends to be more conductive than Ge2Sb2Te5. The resistance versus time measurements under isothermal conditions show that Ge2Sb2Te5 is more thermally stable than Ge1Sb2Te4 and is more suitable for data storage.

[0078] If Ge2Sb2Te5 is processed directly, because the loss rate of Ge element is much faster than that of Sb element, the composition ratio of Ge, Sb and Te may drop from 2:2:5 to 1:2:4. However, the thermal stability of Ge1Sb2Te4 is lower than that of Ge2Sb2Te5. That is, non-target phase change material is obtained after processing the target phase change material, which is not what we expect.

[0079] When processing the phase change materials of the GeSbTe family, the loss of Ge element can be taken into account. If the loss of Ge is m, Ge can be used. (2+m)Sb2Te5 is used as the phase change material to be processed. The part of Ge lost after processing is m, and the target phase change material Ge2Sb2Te5 can be obtained.

[0080] The above embodiment only considers the loss of Ge element during the processing. In one embodiment, the loss of Sb element can also be taken into account. (2+m) Sb (2+n) Te5 is used as the phase change material to be processed, and the part of Ge lost after processing is m, and the part of Sb lost is n. In another embodiment, the loss of Te element can also be taken into consideration, which will not be described in detail here.

[0081] In some embodiments, the preset composition is a composition of the Sb element. The following is a comparative analysis of Ge1Sb2Te4 and Ge3Sb2Te6 after processing:

[0082] In Ge1Sb2Te4, the atomic weight of Ge element accounts for 1 part, and the atomic weight of Sb element accounts for 2 parts. Because the loss rate of Ge element during processing is much faster than that of Sb element, if the amount of Sb element is completely lost during the processing of Ge1Sb2Te4, the amount of Ge element will also be completely lost, which is not what we want.

[0083] In Ge3Sb2Te6, the atomic weight of Ge element accounts for 3 parts, and the atomic weight of Sb element accounts for 2 parts. Because the loss rate of Ge element during processing is much faster than that of Sb element, even if the amount of Sb element is completely lost, Ge element still has 1 part. However, the complete loss of Sb element is a hypothetical limit condition. Because the loss rate of Sb element is much smaller than that of Ge element, as long as the component of Ge element is greater than that of Sb element, Ge can be guaranteed. x Sb y Te z After processing, (x>y) is still a GeSbTe family material and still has the properties of GeSbTe family materials.

[0084] The above embodiments are all examples in which the subscripts of the chemical formula of the GeSbTe family materials represent the proportion of the atomic weight of each element. It should be understood that when the subscripts of the chemical formula of the GeSbTe family materials represent the proportion of each element in the phase change material, the chemical formula of the phase change material to be processed can also be deduced according to the different losses of each element, and the proportion of each element in the chemical formula of the phase change material to be processed is also 100%.

[0085] In some embodiments, the phase change material further includes a third element; wherein the third element is at least one of the elements from Group 3 to Group 13 in the periodic table.

[0086] In phase change memory, a composite material (GST) containing germanium (Ge), antimony (Sb) and tellurium (Te), such as Ge2Sb2Te5, can be used as a phase change material. However, this material has problems such as low crystal transition temperature and poor data retention performance.

[0087] In some embodiments, the stability of the phase change material in the amorphous state can be increased by adding a third element to GST to improve long-term data storage performance while maintaining the property of being able to obtain crystallization at a high speed.

[0088] The added third element may be at least one of Group 3 to Group 13 elements.

[0089] In some embodiments, Sn elements can be added to GST. The phase change material can improve the read and write speed of the device to a certain extent. After adding Sn elements, the speed of writing "0" using the phase change material can be shortened from 200ns to 40ns, and the speed of writing "1" is also reduced from the original 40ns to 10ns. In addition, the speed of reading data is also improved because the resistance of the phase change material in the crystalline state is reduced from 50KΩm to 4KΩm, thereby effectively achieving low power consumption and fast reading and writing.

[0090] In some embodiments, the third element includes an In element.

[0091] In some embodiments, the In element can be added to GST to form a material of the InGeSbTe family. The material of the InGeSbTe family can be made of the chemical formula In m (Ge x Sb y Te z ) (1-m) Expression, where x>y, in some embodiments, 0.01<m<0.2.

[0092] InGeSbTe family materials can be used for In 0.05 (Ge3Sb2Te6) 0.95 Compared with the materials of the GST family, this phase change material can remain amorphous even in a higher temperature environment, so data will not be lost during the welding and crimping processes. Therefore, adding In can improve the stability and data retention ability of the phase change material in the amorphous state while maintaining the characteristic of being able to obtain crystallization at high speed.

[0093] The phase change material in the above embodiment may be a single-layer phase change material.

[0094] In some embodiments, the phase change material has a superlattice-like structure.

[0095] The so-called superlattice phase change material is a material in which different phase change material layers are alternately distributed, and each layer is a few nanometers thick. This optimized design can greatly increase the phase change speed and also improve the structural stability of the phase change layer.

[0096] By forming a superlattice-like structure, the loss of the phase change material can be limited, and the superlattice-like structure can be maintained through high-temperature processing and phase change memory read-write-erase cycles. Therefore, the phase change material with this superlattice structure can improve the RESET current (current during the amorphization process) and cycle of the three-dimensional phase change memory.

[0097] In some embodiments, Figure 3 As shown, the superlattice-like structure includes first material layers 301 and second material layers 302 that are alternately arranged.

[0098] In some embodiments, the first material layer 301 includes the first element;

[0099] The second material layer 302 includes the second element.

[0100] The quasi-superlattice structure includes at least two or more material layers arranged alternately, and the quasi-superlattice structure includes two material layers arranged alternately as an example. In some embodiments, the first element and the second element can be in different material layers respectively. For example, the first element is Ge and the second element is Sb, the first material layer 301 can include Ge, and the second material layer 302 can include Sb.

[0101] In some embodiments, the first element and / or the third element may be used to form the first material layer 301, and the first element and / or the third element may be used to form the second material layer 302. For example, the first element may be Ge, the second element may be Sb, and the third element may be In. The first phase-change material layer 301 may be GeTe, and the second phase-change material layer 302 may be In. x (Sb2Te3) (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 Sb2Te3. The positions of the first phase change layer 301 and the second phase change layer may be interchanged.

[0102] In some embodiments, the composition of the In element is between 1% and 20%.

[0103] The present disclosure also provides a method for preparing a phase change material. Figure 4 As shown, the method includes:

[0104] Step S101, providing a first target material containing at least a first element;

[0105] Step S102, providing a second target material containing at least a second element;

[0106] Step S103, using the first target material and the second target material to form a phase change material containing a first element and a second element; when the phase change material is used to manufacture a phase change memory, the loss of the first element is greater than the second element; the component of the first element in the phase change material is greater than a preset component; wherein the portion of the first element that is greater than the preset component is used to supplement the lost first element.

[0107] The phase change material can be prepared by a deposition process or a growth process.

[0108] The deposition process includes but is not limited to chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced chemical vapor deposition (PECVD), sputtering, metal organic chemical vapor deposition (MOCVD) or atomic layer deposition (ALD), etc.

[0109] In some embodiments, the first material layer or the second material layer may be formed by an epitaxial growth process, and then the second material layer or the first material layer may be formed by a deposition process or a growth process, and this step may be repeated until the desired phase change material is manufactured.

[0110] In some embodiments, the phase change material of the superlattice-like structure may be formed by a deposition process, such as sputtering (eg, RF magnetron sputtering) or atomic layer deposition in a deposition process.

[0111] In one embodiment, the phase change material described in the above embodiment may be manufactured by a sputtering system.

[0112] The sputtering system may include a chamber, a substrate, and the substrate is installed in the chamber. The substrate may be P-type single crystal silicon. A first target material containing at least a first element and a second element may also be provided in the chamber.

[0113] The first target material may be prepared by: first, mixing a first element with a component ratio of x and a second element with a component ratio of y to form a raw material. In some embodiments, other elements may also be included, for example, mixing a first element with a component ratio of x, a second element with a component ratio of y, and other elements with a component ratio of z to form a raw material, and the other elements may be at least one element.

[0114] Then, the raw material is subjected to vacuum melting treatment to obtain a metal compound composed of the first element, the second element, and other elements. The metal compound composed of the first element, the second element, and other elements is then subjected to powder metallurgy treatment to obtain a dry powder composed of the first element, the second element, and other elements.

[0115] Finally, the dried powder composed of the first element, the second element and other elements is subjected to vacuum hot pressing and sintering treatment to obtain a phase change material sputtering target composed of the first element, the second element and other elements.

[0116] The phase change material sputtering target composed of the first element, the second element and other elements is used to form a phase change material containing the first element and the second element through a sputtering process. The loss of the first element in the process of using the phase change material to manufacture a phase change memory is greater than that of the second element, so the component x of the first element in the phase change material is greater than the preset component x1. The part of the first element that is greater than the preset component is used to supplement the lost first element. That is, the loss of the first element is x-x1.

[0117] By increasing the composition of the first element in the sputtering target of the phase change material, the sputtering target is sputtered into a phase change material. The composition ratio of the first element in the phase change material is also x. In the subsequent process of applying the phase change material to manufacture a phase change memory, the loss of the first element is x-x1, and finally the composition of the first element in the phase change material is x1, which is the preset composition and also has the preset performance. In some embodiments, the preset composition can be the composition of the first element under the target performance of the phase change material; in some embodiments, the preset composition can be the composition of the second element.

[0118] In some embodiments, the first element is Ge; and the second element is Sb.

[0119] In some embodiments, the first element is Ge, the second element is Sb, and other elements include but are not limited to Al, Sn, Te, and the like.

[0120] The sputtering target can be Ge x Sb y ,Ge x Sb y A zEtc. The subscripts of the chemical formula can represent the components of the atomic weight of each element, and x is greater than the preset component x1.

[0121] In some embodiments, the phase change material has a superlattice-like structure; and forming the phase change material containing the first element and the second element by using the first target material and the second target material comprises:

[0122] forming at least one first material layer using the first target material;

[0123] The second target material is used to form a second material layer that is arranged alternately with the first material layer.

[0124] In some embodiments, at least two target materials may be used to form a phase change material having a superlattice-like structure.

[0125] In some embodiments, the first target material may contain a first element, and the second target material may contain a second element. Using a sputtering process, a first material layer is first formed on a substrate by sputtering using the first target material, so the first material layer contains the first element, and then a second material layer is formed by sputtering using the second target material, so the second material layer contains the second element. The first material layer and the second material layer may form a composite layer. N composite layers may be formed, for example, 4 layers. This composite layer composed of 4 layers of the first material layer and the second material layer constitutes a phase change material with a superlattice-like structure.

[0126] In some embodiments, the phase change material has a superlattice-like structure; and forming the phase change material containing the first element and the second element by using the first target material and the second target material comprises:

[0127] providing a third target material containing at least a third element;

[0128] Using the first target material and / or the third target material to form at least one first material layer;

[0129] The second target material and / or the third target material are used to form a second material layer arranged alternately with the first material layer.

[0130] In some embodiments, the phase change material of the superlattice-like structure may further include a third element. The phase change material may be formed using three target materials. For example, a third target material containing at least a third element may also be provided in the chamber.

[0131] Using a sputtering process, a first material layer is firstly formed on a substrate by sputtering the first target material and / or the third target material, so the first material layer contains the first element and / or the third element, and then a second material layer is formed by sputtering the second target material and / or the third target material, so the second material layer contains the second element and / or the third element. The first material layer and the second material layer can form a composite layer. N composite layers can be formed, for example, 4 layers. This composite layer composed of 4 layers of the first material layer and the second material layer constitutes a phase change material with a superlattice-like structure.

[0132] In some embodiments, the phase change material has a superlattice-like structure; the first target material and / or the second target material further contains a third element; and the forming of the phase change material containing the first element and the second element by using the first target material and the second target material comprises:

[0133] forming at least one first material layer using the first target material;

[0134] The second target material is used to form a second material layer that is arranged alternately with the first material layer.

[0135] In some embodiments, the superlattice-like phase change material may further have a third element. The phase change material may be formed using two target materials.

[0136] Using a sputtering process, a first material layer is first formed on a substrate by sputtering using a first target material, and the first target material may contain a first element and / or a third element, so the first material layer contains the first element and / or the third element, and then a second material layer is formed by sputtering using a second target material, and the second target material may contain a second element and / or a third element, so the second material layer contains the second element and / or the third element. The first material layer and the second material layer may form a composite layer. N composite layers may be formed, for example, 4 layers. This composite layer composed of 4 layers of the first material layer and the second material layer constitutes a phase change material with a superlattice-like structure.

[0137] In some embodiments, the third element is at least one of Group 3 to Group 13 elements.

[0138] In some embodiments, the third element includes an In element.

[0139] In some embodiments, the first element may be Ge, the second element may be Sb, and the third element may be In. The first phase change material layer may be GeTe, and the second phase change material layer may be In. x (Sb2Te3) (1-x) Or the first phase change material layer may be In x (GeTe) (1-x) , the second phase change material layer may be Sb2Te3. In some embodiments, 1% <x<20%。

[0140] The present disclosure also provides a method for preparing a phase change memory. Figure 5 As shown, the method includes:

[0141] Step S201, forming a first address line layer;

[0142] Step S202, forming a phase change stack 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 comprises: a first element and a second element; wherein the component of the first element in the first phase change material is greater than a preset component;

[0143] Step S203, etching the first address line material layer to form a plurality of first address lines parallel to each other;

[0144] Step S204, etching the phase change stacking layer to form a plurality of mutually unconnected phase change memory stacking bodies; wherein the first phase change material in the first phase change material layer in the phase change memory stacking body after etching is converted into a second phase change material; the composition of the first element in the second phase change material is less than the composition of the first element in the first phase change material and greater than or equal to the preset composition;

[0145] Step S205 , forming a plurality of second address lines parallel to each other on the phase change memory stack; the first address lines are perpendicular to the second address lines.

[0146] In actual process, Fig. 6A As shown, a substrate 300 may be provided first, and a first address line layer 411 may be formed on the substrate 300 by a deposition process or a growth process. The substrate 300 is used to provide support. Here, the substrate 300 may be a semiconductor substrate, and the semiconductor substrate may include a P-type semiconductor material substrate, such as a silicon (Si) substrate or a germanium (Ge) substrate, an N-type semiconductor substrate, such as an indium phosphide (InP) substrate, a composite semiconductor material substrate, such as a silicon germanium (SiGe) substrate, a silicon on insulator (SOI) substrate, and a germanium on insulator (GeOI) substrate. In addition, the substrate 300 in the embodiment of the present disclosure may also be a substrate on which a partial device structure has been formed, or which has some wiring, which is not limited here.

[0147] 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 other address line layers (e.g., the second address line layer) involved in subsequent process steps may be selected from the above materials.

[0148] A phase change stack layer 410 is formed on the first address line layer 411 by a deposition process or a growth process.

[0149] along Fig. 6A In the second direction shown in FIG. 1 , the first address line layer 411 and the phase change stack layer 410 are etched. Specifically, a mask can be formed on the phase change memory stack layer 410, and the mask is 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. Figure 6B The plurality of phase change memory stack strips 410a and the plurality of first address lines 411a are shown. The etching method includes but is not limited to dry etching and wet etching.

[0150] Then, a deposition process or a growth process is used to form a plurality of phase change memory stack strips 410a. Figure 6C The second address line layer 422 is shown.

[0151] along Figure 6C The second address line layer 422 and the plurality of phase change stacked strips 410a are etched in the first direction as shown. Specifically, a mask can be formed on the second address line layer 422, and the mask is patterned by exposure and development. The second address line layer 422 and the plurality of phase change stacked strips 410a are etched along the first direction based on the patterned hard mask. Fig.6D The plurality of phase change memory stacks 410b and at least one second address line 422a are shown. The etching method includes but is not limited to dry etching and wet etching.

[0152] The first address line 411a can be used as a word line or a bit line, and the second address line 422a can also be used as a word line or a bit line. In some embodiments, the first address line 411a can be a bit line, and the second address line 422a can be a word line.

[0153] In some embodiments, Fig. 6A As shown, the forming of the phase change stack layer 410 on the first address line material layer 411 includes:

[0154] A first lower electrode layer 401 , a first bidirectional threshold switch layer 402 , a first intermediate electrode layer 403 , the first phase change material layer 404 and a first upper electrode layer 405 which are stacked in sequence are formed on the first address line material layer 410 .

[0155] The phase change memory stack layer 410 may include a stacked first phase change material layer 404, a first bidirectional threshold switch layer 402, and a plurality of electrode material layers. Fig. 6AAs shown, for example, it includes a first lower electrode layer 401, a first bidirectional threshold switch layer 402, a first intermediate electrode layer 403, a first phase change material layer 404 and a first upper electrode layer 405 stacked in sequence. Here, each layer of the first upper electrode layer 405, the first lower electrode layer 401 and the first intermediate electrode layer 403 may include a conductive material, and the conductive material includes but is not limited to W, Co, Cu, Al, carbon, polysilicon, doped silicon, silicide or any combination thereof. In some embodiments, the positions of the bidirectional threshold switch layer 402 and the phase change material layer 404 can be interchanged.

[0156] In some embodiments, each of the first upper electrode layer 405, the first lower electrode layer 401, and the first intermediate electrode layer 403 includes carbon, such as amorphous carbon (ac), carbon nanotubes, or graphene. The material of the first bidirectional threshold switch layer 402 may include a chalcogenide material, such as ZnxTey, GexTey, NbxOy, or SixAsyTez. The phase change material of the first phase change material layer 404 is a first phase change material, and the first phase change material includes: a first element and a second element; wherein the loss of the first element in the process of applying the first phase change material to manufacture a phase change memory is greater than the loss of the second element. The component of the first element in the first phase change material is greater than a preset component; wherein the portion of the first element greater than the preset component is used to supplement the loss of the first element. The first phase change material layer forms the second phase change material layer 404a in the phase change memory stack 410b after a processing process (e.g., an etching process, a cleaning process), and the component of the first element in the third phase change material layer 404b is a preset component. The composition of the first element in the phase change memory stack 410 b is a preset composition, ie, has preset properties.

[0157] In some embodiments, the predetermined composition may be a composition of the second element; in some embodiments, the predetermined composition may be a composition of the first element under the target performance of the phase change material.

[0158] The structure, configuration and material of the phase-change memory stack layer 410 and the phase-change memory stack body 410 b formed after etching are not limited thereto, and may include any appropriate structure, configuration and material.

[0159] Figure 7 It is an example of a phase change memory cell array, which includes a plurality of phase change memory cells 500, each of which has a first conductive line 501 above and a second conductive line 509 below. Each phase change memory cell 500 includes: an upper electrode 502, a phase change material 504, and a first conductive layer 503 and a second conductive layer 505 located on the upper and lower sides of the phase change material 504, an intermediate electrode 506, a bidirectional threshold switch 507, and a lower electrode 508. The left and right side walls of the phase change material 504 also include a liner layer 510, a first dielectric layer 511, and a sidewall layer 512.

[0160] The material of the first conductive line 501 and the material of the second conductive line 509 may include a conductive material, which includes but is not limited to tungsten (W), cobalt (Co), copper (Cu), aluminum (Al), polysilicon, doped silicon, silicide, or any combination thereof.

[0161] The first conductive line 501 can be used as a bit line or a word line; the second conductive line 509 can also be used as a word line or a bit line. For example, when the first conductive line 501 is used as a bit line, the second conductive line 509 can be used as a word line. The phase change memory cell is used to store data based on the phase change of the voltage difference between the first conductive line and the second conductive line.

[0162] The materials of the upper electrode 502 , the middle electrode 506 , and the lower electrode 508 include carbon-containing materials, and the carbon-containing materials include but are not limited to amorphous carbon (ac), carbon nanotubes, graphene, and the like.

[0163] The first conductive layer 503 and the second conductive layer 505 can be used to improve the contact sensitivity between the phase change material 504 and 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.

[0164] The material of the bidirectional threshold switch 507 may include a chalcogenide material, for example, Ge-Se, Si-Te, C-Te, B-Te, Ge-Te, Al-Te, Ge-Sb-Te, Ge-Sb, Bi-Te, As-Te, Sn-Te, Ge-Te-Pb or Ge-Se-Te, etc.

[0165] The material of the phase change material 504 can be obtained by processing the phase change material described in the embodiment of the present disclosure, and the phase change material described in the embodiment of the present disclosure includes a first element and a second element; wherein, in the process of applying the phase change material to manufacture a phase change memory, the loss of the first element is greater than that of the second element; the component of the first element in the phase change material is greater than a preset component; wherein, the portion of the first element that is greater than the preset component is used to supplement the lost first element.

[0166] A first gap filling layer (Gap Fill) 514 is further included between each phase change memory cell 500, and the sidewalls of the phase change memory cell array further include a second gap filling layer 513 and a second dielectric layer 515. Examples of gap filling materials 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), lead selenide (PbSe), and cobalt-based compounds and any combination thereof.

[0167] The materials of the first gap-filling layer 514 and the second gap-filling layer 513 may be the same or different.

[0168] The material of the second dielectric layer 515 may be oxide. The material of the first dielectric layer 511 may be the same as or different from that of the second dielectric layer 515.

[0169] In some embodiments, the positions of the phase change material 504 and the bidirectional threshold switch 507 may be interchanged.

[0170] The phase change memory cell array and the peripheral circuit can constitute a phase change memory.

[0171] The present disclosure also provides a phase change memory, including:

[0172] A first address line layer; wherein the first address line layer includes a plurality of first address lines parallel to each other;

[0173] A second address line layer; wherein the second address line layer includes a plurality of second address lines parallel to each other;

[0174] A phase change stacking layer located between the first address line layer and the second address line layer; the phase change stacking layer comprises a phase change material layer; wherein the composition of a first element in the phase change material of the phase change material layer when formed is greater than a preset composition; a portion of the first element greater than the preset composition is used to supplement the first element lost in the process of forming the phase change stacking layer.

[0175] In some embodiments, the phase change stack layer comprises:

[0176] A lower electrode layer, a bidirectional threshold switch layer, an intermediate electrode layer, the phase change material layer and an upper electrode layer are stacked in sequence.

[0177] The phase change material proposed in the embodiment of the present disclosure has better thermal stability, faster SET speed, lower RESET current and high endurance cycle compared to the phase change material before improvement.

[0178] It should be understood that “some embodiments”, “one embodiment” or “an embodiment” mentioned throughout the specification means that specific features, structures or characteristics related to the embodiments are included in at least one embodiment of the present disclosure. Therefore, “in one embodiment” or “in an embodiment” appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present disclosure, the size of the serial number of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure. The serial numbers of the embodiments of the present disclosure are for description only and do not represent the advantages and disadvantages of the embodiments.

[0179] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0180] The above is only an embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A phase change material, characterized in that: The phase change material is applied to a phase change memory; the phase change material comprises: A first element and a second element; wherein, in the process of applying the phase change material to manufacture a phase change memory, the loss of the first element is greater than that of the second element; The composition of the first element in the phase change material is greater than a preset composition; wherein the portion of the first element that is greater than the preset composition is used to supplement the lost first element.

2. The phase change material according to claim 1, characterized in that: The first element is Ge; the second element is Sb.

3. The phase change material according to claim 1, characterized in that: The phase change material further includes a third element; wherein the third element is at least one of the elements of Groups 3 to 13 in the periodic table.

4. The phase change material according to claim 3, characterized in that: The third element includes an In element.

5. The phase change material according to claim 1, characterized in that: The phase change material has a superlattice-like structure.

6. The phase change material according to claim 5, characterized in that: The superlattice-like structure includes first material layers and second material layers which are alternately arranged.

7. The phase change material according to claim 6, characterized in that: The first material layer includes the first element; The second material layer includes the second element.

8. A method for preparing a phase change material, characterized in that: The method comprises: providing a first target material containing at least a first element; providing a second target material containing at least a second element; A phase change material comprising a first element and a second element is formed using the first target material and the second target material; during the process of using the phase change material in manufacturing a phase change memory, the loss of the first element is greater than the second element; the composition of the first element in the phase change material is greater than a preset composition; wherein the portion of the first element that is greater than the preset composition is used to supplement the lost first element.

9. The method for preparing a phase change material according to claim 8, characterized in that: The first element is Ge; the second element is Sb.

10. The method for preparing a phase change material according to claim 8, characterized in that: The phase change material has a superlattice-like structure; and the step of using the first target material and the second target material to form a phase change material containing a first element and a second element comprises: forming at least one first material layer using the first target material; The second target material is used to form a second material layer that is arranged alternately with the first material layer.

11. The method for preparing a phase change material according to claim 8, characterized in that: The phase change material has a superlattice-like structure; and the forming of the phase change material containing the first element and the second element by using the first target material and the second target material comprises: providing a third target material containing at least a third element; Using the first target material and / or the third target material to form at least one first material layer; The second target material and / or the third target material are used to form a second material layer arranged alternately with the first material layer.

12. The method for preparing a phase change material according to claim 8, characterized in that: The phase change material has a superlattice-like structure; the first target material and / or the second target material further contains a third element; and the forming of the phase change material containing the first element and the second element by using the first target material and the second target material comprises: forming at least one first material layer using the first target material; The second target material is used to form a second material layer that is arranged alternately with the first material layer.

13. The method for preparing a phase change material according to claim 11 or 12, characterized in that: 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, characterized in that: The third element includes an In element.

15. A method for preparing a phase change memory, characterized in that: The method comprises: forming a first address line layer; A phase change stacking layer is formed on the first address line layer; the phase change stacking layer comprises a phase change material layer; the material of the phase change material layer is a first phase change material; the first phase change material comprises: a first element and a second element; wherein the component of the first element in the first phase change material is greater than a preset component; Etching the first address line material layer to form a plurality of first address lines parallel to each other; Etching the phase change stacking layer to form a plurality of mutually unconnected phase change memory stacking bodies; wherein the material of the phase change material layer in the etched phase change memory stacking body 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 preset composition; A plurality of second address lines parallel to each other are formed on the phase-change memory stack; the first address lines are perpendicular to the second address lines.

16. The method for preparing a phase change memory according to claim 15, characterized in that: The forming of a phase change stack layer on the first address line material layer comprises: A lower electrode layer, a bidirectional threshold switch layer, an intermediate electrode layer, the phase change material layer and an upper electrode layer are sequentially stacked on the first address line material layer.

17. A phase change memory, characterized in that: include: 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 stacking layer located between the first address line layer and the second address line layer; the phase change stacking layer comprises a phase change material layer; wherein the composition of a first element in the phase change material of the phase change material layer when formed is greater than a preset composition; a portion of the first element greater than the preset composition is used to supplement the first element lost in the process of forming the phase change stacking layer.

18. The phase change memory according to claim 17, characterized in that: The phase change stacking layer comprises: A lower electrode layer, a bidirectional threshold switch layer, an intermediate electrode layer, the phase change material layer and an upper electrode layer are stacked in sequence.

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