Phase change memory and storage system
By partitioning the phase change memory layer into different phase change regions with varying antimony content or crystallization temperatures, the problem of thermal crosstalk caused by antimony segregation in the phase change memory is solved, thus improving the stability and performance of the memory.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 新存科技(武汉)有限责任公司
- Filing Date
- 2025-01-10
- Publication Date
- 2026-07-10
AI Technical Summary
Elemental segregation of phase change materials in phase change memory leads to further deterioration of thermal crosstalk, affecting memory performance.
By partitioning the phase change storage layer into a first phase change region and a second phase change region, the antimony content in the material of the first phase change region is greater than that in the second phase change region, or the crystallization temperature of the first phase change region is higher than that of the second phase change region, thus improving the effect of element segregation.
It effectively improves the thermal crosstalk problem caused by antimony segregation, and enhances the stability and performance of phase change memory.
Smart Images
Figure CN122373364A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of memory technology, and in particular to a phase-change memory and a memory system. Background Technology
[0002] Phase-change memory (PCM) relies on the Joule heating of current to operate the phase-change material in the PCM cell, causing it to transition between a crystalline (low resistance) and an amorphous (high resistance) state, thereby enabling the write (SET) and erase (RESET) switching to complete data storage. Both the SET and RESET processes in PCM are related to Joule heating of current; an unreasonable thermal field distribution can increase the probability of erase / write errors.
[0003] During the RESET process, thermal disturbances can cause the temperature of adjacent phase change memory cells in the memory array to increase. The high temperature distribution of adjacent phase change memory cells is mainly at the bottom. At the same time, during read and write operations, the composition of the phase change material will segregate. The high temperature at the bottom of the phase change memory layer, coupled with the low crystallization temperature of the phase change material due to element segregation, will further aggravate thermal crosstalk, thereby increasing the probability of erase / write errors and affecting the performance of the phase change memory. Summary of the Invention
[0004] This application provides a phase change memory and a storage system. The phase change memory of this application can effectively improve the elemental segregation problem of phase change materials, thereby improving the thermal crosstalk deterioration problem of the phase change memory.
[0005] To achieve the above objectives, according to a first aspect of this application, a phase-change memory is provided, the phase-change memory comprising:
[0006] At least one first conductive layer;
[0007] At least one second conductive layer is stacked relative to the first conductive layer along a first direction; and
[0008] At least one first phase change memory cell is disposed between the first conductive layer and the second conductive layer. The first phase change memory cell includes a first phase change memory layer, and the first phase change memory layer includes a first phase change region and a second phase change region. The second phase change region and the first phase change region are stacked along the first direction. The direction of the current in the phase change memory is from the first conductive layer to the second conductive layer, and the distance from the first phase change region to the first conductive layer is less than the distance from the second phase change region to the first conductive layer.
[0009] Wherein, the material of the first phase transition region contains a first element, the content of the first element in the material of the first phase transition region is greater than the content of the first element in the material of the second phase transition region, and the first element is antimony.
[0010] Alternatively, the material of the first phase transition region contains a second element, which causes the crystallization temperature of the material of the first phase transition region to be greater than the crystallization temperature of the material of the second phase transition region.
[0011] In some embodiments, the second element is at least one of germanium, indium, or nitrogen.
[0012] In some embodiments, when the material of the first phase transition region contains the first element, the material of the second phase transition region also contains the first element, and the content of the first element in the material of the first phase transition region is 1% to 15% higher than the content of the first element in the material of the second phase transition region.
[0013] In some embodiments, when the material of the first phase transition region contains the second element, the material of the second phase transition region also contains the second element, and the content of the second element in the material of the first phase transition region is 1% to 25% higher than the content of the second element in the material of the second phase transition region.
[0014] In some embodiments, the first phase change storage layer further includes at least one third phase change region, the third phase change region being located between the first phase change region and the second phase change region;
[0015] The content of the first element in the material of the third phase transition region is less than the content of the first element in the material of the first phase transition region, but greater than the content of the first element in the material of the second phase transition region.
[0016] Alternatively, the content of the second element in the material of the third phase transition region is less than the content of the second element in the material of the first phase transition region, but greater than the content of the second element in the material of the second phase transition region.
[0017] In some embodiments, the first phase change storage layer includes a plurality of third phase change regions, the plurality of third phase change regions are stacked along the first direction, and the content of a first element in the material of the plurality of third phase change regions of the first conductive layer increases along the first direction relative to the first conductive layer.
[0018] In some embodiments, the material of the first phase transition region is a phase transition material with doped particles, wherein the element of the doped particles is the first element or the second element; the material of the second phase transition region is a phase transition material, wherein the phase transition material includes a germanium-antimony-tellurium compound.
[0019] In some embodiments, the phase change memory further includes a substrate and at least one second phase change memory cell; along the first direction, the second conductive layer, the first phase change memory cell, the first conductive layer, and the second phase change memory cell are stacked on the substrate, and the distance from the first phase change memory cell to the substrate is less than the distance from the second phase change memory cell to the substrate;
[0020] The second phase change memory unit includes a second phase change memory layer, and the material of the second phase change memory layer is the same as the material of the second phase change region.
[0021] In some embodiments, the first phase change memory cell further includes a first gate layer, which is located between the first phase change memory layer and the first conductive layer, or between the first phase change memory layer and the second conductive layer.
[0022] According to a second aspect of this application, a storage system is provided, the storage system comprising:
[0023] Phase-change memory as described in the first aspect; and
[0024] A controller, connected to the phase change memory, is used to control the phase change memory to store data.
[0025] This application provides a phase change memory and a storage system. The phase change memory of this application includes at least a first phase change memory cell, the first phase change memory cell includes a first phase change memory layer, and the first phase change memory layer includes a first phase change region and a second phase change region stacked along the current direction. The material of the first phase change region contains a first element, and the content of the first element in the material of the first phase change region is greater than the content of the first element in the material of the second phase change region. The first element is antimony. Alternatively, the material of the first phase change region contains a second element, and the second element causes the crystallization temperature of the material of the first phase change region to be greater than the crystallization temperature of the material of the second phase change region.
[0026] When the material of the first phase change region contains antimony (Sb), that is, when the antimony (Sb) content in the material of the first phase change region is greater than that in the material of the second phase change region, antimony (Sb) will move along the current direction when antimony (Sb) segregates in the first phase change storage layer. The antimony (Sb) in the material of the first phase change region will move into the material of the second phase change region. Eventually, the antimony (Sb) content in the material of the first phase change region and the antimony (Sb) content in the material of the second phase change region can be brought into balance. This application balances the effect of antimony (Sb) segregation in the first phase change storage layer by making the antimony (Sb) content in the material of the first phase change region greater than that in the material of the second phase change region, thereby improving the problem of further deterioration of thermal crosstalk caused by antimony (Sb) segregation.
[0027] When the material in the first phase transition region contains the second element, the crystallization temperature of the material in the first phase transition region is higher than that of the material in the second phase transition region. The material in the first phase transition region is more stable and can restrict the movement of antimony (Sb) element, thereby improving the segregation process of antimony (Sb) element and thus improving the problem of further deterioration of thermal crosstalk caused by antimony (Sb) element segregation. Attached Figure Description
[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0029] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.
[0030] Figure 1 This is a schematic diagram of the structure of a three-dimensional phase-change memory in the prior art;
[0031] Figure 2 yes Figure 1 Crystallization temperature curve of the lower phase change memory cell in a three-dimensional phase change memory;
[0032] Figure 3 yes Figure 1 Temperature distribution diagram of the lower phase change memory cell in a three-dimensional phase change memory;
[0033] Figure 4 This is a schematic diagram of the structure of one type of phase-change memory provided in the embodiments of this application;
[0034] Figure 5This is a schematic diagram of the structure of one type of phase-change memory provided in the embodiments of this application;
[0035] Figure 6 yes Figure 1 Crystallization temperature curve of the upper phase change memory cell in a three-dimensional phase change memory;
[0036] Figure 7 yes Figure 1 Temperature distribution diagram of the upper phase change memory cell in a three-dimensional phase change memory;
[0037] Figure 8 This is a schematic diagram of the structure of one type of phase-change memory provided in the embodiments of this application.
[0038] Explanation of reference numerals in the attached figures:
[0039] 10. Phase-change memory; 100. Substrate; 101. Word line; 102. Bit line; 103. Phase-change memory cell; 104. Bottom electrode; 105. Gating layer; 106. Intermediate electrode; 107. Phase-change memory layer; 108. Top electrode; 111. First conductive layer; 112. Second conductive layer; 113. Third conductive layer; 114. Fourth conductive layer; 115. Fifth conductive layer; 121. First phase-change memory cell; 122. Second phase-change memory cell; 123. Third phase-change memory cell; 124. Fourth phase-change memory cell; 201. First conductive layer; 2011. First conductive layer; Wire; 202, Second conductive layer; 2021, Second conductive wire; 203, First phase change memory cell; 204, First bottom electrode; 205, First gate layer; 206, First intermediate electrode; 207, First phase change memory layer; 2071, First phase change region; 2072, Second phase change region; 2073, Third phase change region; 208, First top electrode; 209, First linear barrier layer; 303, Second phase change memory cell; 304, Second bottom electrode; 305, Second gate layer; 306, Second intermediate electrode; 307, Second phase change memory layer; 308, Second top electrode; 309, Second linear barrier layer. Detailed Implementation
[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.
[0041] Please refer to Figure 1This is a schematic diagram of a three-dimensional phase-change memory (PCM). The PCM includes multiple word lines (WL) 101, multiple bit lines (BL) 102, and multiple PCM cells 103. Taking a two-layer structure PCM as an example, the PCM includes two layers of PCM cells 103 stacked along the first direction Z, word lines 101 located between the two layers of PCM cells 103, and bit lines 102 located on the side of the PCM cells 103 away from the word lines 101. Further, the PCM cells 103 include a bottom electrode (BE) 104, an overlay layer (OTS) 105, an intermediate electrode (ME) 106, a PCM layer (PCM) 107, and a top electrode (TE) 108 stacked along the first direction Z. The PCM layer 107 includes a phase change material, which is a chalcogenide compound GST (Ge-Sb-Te).
[0042] During the read and write operations of a phase-change memory (PCM), some elements in the PCM material undergo segregation, causing changes in the distribution of some elements. For example, antimony (Sb) in the PCM material moves along the direction of the electric field (from word line 101 to bit line 102), while tellurium (Te) moves against the direction of the electric field. After a certain number of operations, the PCM layer 107 near word line 101 will have less antimony (Sb). However, the less antimony (Sb), the higher the crystallization activation energy, resulting in a higher crystallization temperature of the material near word line 101 in the PCM layer 107. Meanwhile, the PCM layer near bit line 102 will be enriched with antimony (Sb). However, the enrichment of antimony (Sb) results in a lower crystallization activation energy, resulting in a lower crystallization temperature of the material near bit line 102 in the PCM layer 107.
[0043] Please refer to Figures 2-3 , Figure 2 yes Figure 1 Crystallization temperature curves of the lower-level phase change memory cells in a three-dimensional phase change memory. Figure 2 Curve a represents the temperature curve of a phase change memory cell without elemental segregation, and curve b represents the temperature curve of a phase change memory cell with elemental segregation. The horizontal axis represents the position of the phase change memory cell in the Z direction, and the vertical axis represents the temperature. Figure 3 yes Figure 1 Temperature distribution diagrams of the lower-level phase change memory cells in a three-dimensional phase change memory include temperature distribution diagrams in plan view and cross view of phase change memory cells without elemental segregation and phase change memory cells with elemental segregation.
[0044] Depend on Figure 2 It can be seen that the top crystallization temperature of phase change memory cells where elemental segregation occurs is higher, while the bottom crystallization temperature is lower. (From...) Figure 3It can be seen that the high-temperature distribution area of the phase change memory cell without element segregation is mainly at the bottom. For the phase change memory cell with element segregation, the high-temperature distribution area becomes the top. This proves that the high temperature at the bottom of the phase change memory layer, coupled with the low crystallization temperature at the bottom of the phase change material due to element segregation, will lead to the deterioration of thermal crosstalk. In other words, element segregation will further deteriorate the thermal crosstalk of the phase change memory cell.
[0045] To address the aforementioned issues, this application provides a phase-change memory 10 to resolve the problem of further deterioration of thermal crosstalk in phase-change memory cells caused by element segregation in the phase-change memory layer.
[0046] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of a phase-change memory 10 provided in an embodiment of this application. The phase-change memory 10 includes at least one first conductive layer 201, at least one second conductive layer 202, and at least one first phase-change memory cell 203. The second conductive layer 202 and the first conductive layer 201 are stacked together along a first direction Z. The first phase change memory unit 203 is disposed between the first conductive layer 201 and the second conductive layer 202. The first phase change memory unit 203 includes a first phase change memory layer 207, which includes a first phase change region 2071 and a second phase change region 2072. The second phase change region 2072 and the first phase change region 2071 are stacked along a first direction Z, which is perpendicular to the first conductive layer 201 and the second conductive layer 202. The direction of the current I in the phase change memory 10 is from the first conductive layer 201 to the second conductive layer 202, and the distance from the first phase change region 2071 to the first conductive layer 201 is less than the distance from the second phase change region 2072 to the first conductive layer 201.
[0047] The material of the first phase transition region 2071 contains a first element, and the content of the first element in the material of the first phase transition region 2071 is greater than the content of the first element in the material of the second phase transition region 2072. The first element is antimony (Sb).
[0048] Alternatively, the material of the first phase transition region 2071 may contain a second element, which causes the crystallization temperature of the material of the first phase transition region 2071 to be greater than the crystallization temperature of the material of the second phase transition region 2072.
[0049] Content refers to the mass fraction or mass percentage of an element.
[0050] This application improves the effect of element segregation by partitioning the first phase change memory layer 207 so that the contents of the first element or the second element in the material of the first phase change region 2071 and the material of the second phase change region 2072 are different, thereby improving the thermal crosstalk deterioration problem of the phase change memory.
[0051] In some embodiments, the materials of the first phase transition region 2071 and the second phase transition region 2072 both contain a first element, and the content of the first element in the material of the first phase transition region 2071 is greater than the content of the first element in the material of the second phase transition region 2072. The first element is antimony (Sb). For example, the phase transition materials of the first phase transition region 2071 and the second phase transition region 2072 can both be chalcogenide compounds GST, that is, containing germanium (Ge), antimony (Sb), and tellurium (Te), wherein the content of antimony (Sb) in the material of the first phase transition region 2071 is greater than the content of antimony (Sb) in the material of the second phase transition region 2072.
[0052] In this embodiment, the first element is antimony (Sb). The antimony (Sb) content in the material of the first phase change region 2071 is greater than that in the material of the second phase change region 2072. During the read / write process of the phase change memory, the antimony (Sb) in the first phase change storage layer 207 will segregate, and the antimony (Sb) will move along the current direction, that is, the antimony (Sb) in the first phase change region 2071 will move into the second phase change region 2072. The content will decrease, and the antimony (Sb) content in the material of the second phase transition region 2072 will increase accordingly. Eventually, the antimony (Sb) content in the material of the first phase transition region 2071 and the antimony (Sb) content in the material of the second phase transition region 2072 can be brought into balance, making the overall distribution of antimony (Sb) in the first phase transition storage layer 207 more uniform. This can improve the problem of further deterioration of thermal crosstalk caused by the uneven distribution of antimony (Sb) in the first phase transition storage layer 207 due to antimony (Sb) segregation.
[0053] Furthermore, when the first element is antimony (Sb), the content of the first element in the material of the first phase transition region 2071 is 1% to 15% higher than the content of the first element in the material of the second phase transition region 2072. When the content of antimony (Sb) in the material of the first phase transition region 2071 and the content of antimony (Sb) in the material of the second phase transition region 2072 are within the above range, the content of antimony (Sb) in the material of the first phase transition region 2071 after segregation tends to be balanced with the content of antimony (Sb) in the material of the second phase transition region 2072, without causing the content of antimony (Sb) in the material of the first phase transition region 2071 to be too high and affecting the overall performance of the first phase transition memory layer 207.
[0054] In some embodiments, the materials of the first phase transition region 2071 and the second phase transition region 2072 both contain a second element, and the content of the second element in the material of the first phase transition region 2071 is greater than the content of the second element in the material of the second phase transition region 2072. The second element is at least one of germanium (Ge), indium (In), or nitrogen (N).
[0055] In this embodiment, the second element is germanium (Ge), indium (In), or nitrogen (N). The content of the second element in the material of the first phase transition region 2071 is greater than that in the material of the second phase transition region 2072. That is, the first phase transition region 2071 is a material enriched with germanium (Ge), indium (In), or nitrogen (N). The crystallization temperature of the material enriched with germanium (Ge), indium (In), or nitrogen (N) is higher. Therefore, the crystallization temperature of the material of the first phase transition region 2071 is higher than that of the material of the second phase transition region 2072. The higher the crystallization temperature, the more stable the material. This makes the material of the first phase transition region 2071 more stable and can limit the movement of antimony (Sb) to improve the segregation process of antimony (Sb), thereby improving the problem of further deterioration of thermal crosstalk caused by antimony (Sb) segregation.
[0056] For example, when the second element is germanium (Ge), the phase transition materials of the first phase transition region 2071 and the second phase transition region 2072 can both be germanium-antimony-tellurium compounds (GST). The content of germanium (Ge) in the material of the first phase transition region 2071 is greater than that in the material of the second phase transition region 2072. Since the first phase transition region 2071 is a material enriched in germanium (Ge), and the enrichment of germanium (Ge) makes the crystallization temperature of the material higher, the crystallization temperature of the material of the first phase transition region 2071 is greater than that of the material of the second phase transition region 2072, and the material of the first phase transition region 2071 is more stable. Meanwhile, germanium (Ge) has a higher crystallization temperature than antimony (Sb), and its structure and properties are relatively more stable, making it less prone to segregation. When the germanium (Ge) content in the first phase transition region 2071 is high, germanium (Ge) can block and bind the movement of antimony (Sb) and tellurium (Te), thereby reducing the segregation of antimony (Sb) and thus improving the problem of further deterioration of thermal crosstalk caused by antimony (Sb) segregation.
[0057] When the second element is indium (In) or nitrogen (N), the principle is similar to that when the second element is germanium (Ge). Because the enrichment of indium (In) or nitrogen (N) increases the crystallization temperature of the material in the first phase transition region 2071, the material becomes more stable, which restricts the movement of antimony (Sb) and improves the antimony (Sb) segregation process. This, in turn, mitigates the problem of further deterioration of thermal crosstalk caused by antimony (Sb) segregation.
[0058] In some embodiments, when the second element is germanium (Ge), indium (In), or nitrogen (N), the content of the second element in the material of the first phase change region 2071 is 1% to 25% higher than the content of the second element in the material of the second phase change region 2072. When the relationship between the content of the second element in the material of the first phase change region 2071 and the content of the second element in the material of the second phase change region 2072 is within the above range, the segregation process of antimony (Sb) can be improved without causing the content of the second element in the material of the first phase change region 2071 to be too high and thus affecting the overall performance of the first phase change memory layer 207.
[0059] In some embodiments, the content of the second element in the material of the second phase transition region 2072 may be zero, that is, the second element is only contained in the material of the first phase transition region 2071. For example, the material of the first phase transition region 2071 may contain indium (In) or nitrogen (N), while the material of the second phase transition region 2072 does not contain indium (In) or nitrogen (N).
[0060] In some embodiments, the material of the first phase transition region 2071 is a phase transition material with doped particles, and the element of the doped particles is a first element or a second element; the material of the second phase transition region 2072 is a phase transition material.
[0061] Specifically, the first phase transition region 2071 may include a first phase transition material, and the second phase transition region 2072 may include a second phase transition material. The first phase transition material is a second phase transition material doped with a first element or a second element. The second phase transition material can be a conventional chalcogenide compound GST, i.e., a germanium-antimony-tellurium compound. The first phase transition material can be obtained by further doping the second phase transition material with a first element or a second element, thereby making the content of the first element in the first phase transition material greater than the content of the first element in the second phase transition material, or the content of the second element in the first phase transition material greater than the content of the second element in the second phase transition material.
[0062] For example, the second phase change material can be a conventional chalcogenide compound phase change material such as GST225 or GST124. Correspondingly, the first phase change material can be GST225 or GST124 doped with antimony (Sb), or GST225 or GST124 doped with germanium (Ge), or GST225 or GST124 doped with indium (In), or GST225 or GST124 doped with nitrogen (N), but is not limited to these.
[0063] In the above embodiments, the content of the first element in the first phase change material refers to the mass percentage of the first element in the first phase change material. For example, the content of the first element in the first phase change material = [(number of atoms of the first element × relative atomic mass of the first element) / relative molecular mass of the first phase change material] × 100%. The content of the first element in the second phase change material is defined similarly to that in the first phase change material.
[0064] In some embodiments, please refer to Figure 5 The first phase change storage layer 207 further includes at least one third phase change region 2073, which is located between the first phase change region 2071 and the second phase change region 2072. The content of the first element in the material of the third phase change region 2073 is less than the content of the first element in the material of the first phase change region 2071, but greater than the content of the first element in the material of the second phase change region 2072; or the content of the second element in the material of the third phase change region 2073 is less than the content of the second element in the material of the first phase change region 2071, but greater than the content of the second element in the material of the second phase change region 2072. The third phase change region 2073 can serve as a transition layer, preventing abrupt changes in the content of the first or second element between the first phase change region 2071 and the second phase change region 2072, thus ensuring a reasonable distribution of antimony (Sb) in the first phase change storage layer 207 and further improving the overall performance of the first phase change storage layer 207.
[0065] When the material of the first phase transition region 2071 contains antimony (Sb) as the first element, the content of antimony (Sb) in the materials of the first phase transition region 2071, the third phase transition region 2073, and the second phase transition region 2072 decreases sequentially. Because antimony (Sb) segregates, it moves from the first phase transition region 2071 to the third phase transition region 2073 and then to the second phase transition region 2072, causing the content of antimony (Sb) in the materials of the first phase transition region 2071, the third phase transition region 2073, and the second phase transition region 2072 to decrease sequentially. After antimony (Sb) segregation occurs, it is beneficial for the first phase transition storage layer 207 to achieve a more uniform distribution of antimony (Sb) overall.
[0066] When the material of the first phase transition region 2071 contains the second element germanium (Ge), indium (In), or nitrogen (N), the content of the second element in the first phase transition region 2071, the third phase transition region 2073, and the second phase transition region 2072 decreases sequentially. Since a higher content of the second element results in a more stable phase transition material and a greater binding effect on the movement of antimony (Sb), and the amount of antimony (Sb) segregated gradually decreases along the current direction, the binding effect required for the movement of antimony (Sb) in the first phase transition region 2071, the third phase transition region 2073, and the second phase transition region 2072 gradually decreases. Correspondingly, the content of the second element in the materials of the first phase transition region 2071, the third phase transition region 2073, and the second phase transition region 2072 can be decreased sequentially to rationally utilize the content of the first element to improve the process of antimony (Sb) segregation.
[0067] In some embodiments, please refer to Figure 5 The first phase change storage layer 207 may include a plurality of third phase change regions 2073, which are stacked along a first direction Z. The content of the first element in the plurality of third phase change regions 2073 increases relative to the first conductive layer 201 along the first direction Z. In this embodiment, the first phase change storage layer 207 includes a first phase change region 2071, a plurality of third phase change regions 2073, and a second phase change region 2072 stacked together. The content of the first element in the plurality of phase change regions gradually increases along the first direction Z, so that the first phase change storage layer 207 as a whole forms a structure with a gradually changing content of the first element along the first direction Z, thereby gradually improving the segregation process of antimony (Sb) in the first phase change storage layer 207 and improving the overall performance of the first phase change storage layer 207.
[0068] In this application, the materials of the first phase transition region 2071, the third phase transition region 2073, and the second phase transition region 2072 can be formed by layer-by-layer deposition, but are not limited thereto.
[0069] In some embodiments, please refer to Figures 4-5 The phase change memory 10 further includes at least one second phase change memory cell 303, which is disposed on the side of the first conductive layer 201 away from the first phase change memory layer 207, and includes the second phase change memory layer 307.
[0070] In some embodiments, please refer to Figures 4-5 The phase change memory 10 also includes a substrate 100. Along the first direction Z, a second conductive layer 202, a first phase change memory cell 203, a first conductive layer 201, and a second phase change memory cell 303 are stacked on the substrate 100. The distance from the first phase change memory cell 203 to the substrate 100 is less than the distance from the second phase change memory cell 303 to the substrate 100.
[0071] Please refer to Figures 6-7 , Figure 6 yes Figure 1 Crystallization temperature curves of the upper phase change memory cells in a three-dimensional phase change memory. Figure 6 Curve a represents the temperature curve of a phase change memory cell without elemental segregation, and curve b represents the temperature curve of a phase change memory cell with elemental segregation. The horizontal axis represents the position of the phase change memory cell in the Z direction, and the vertical axis represents the temperature. Figure 7 yes Figure 1 Temperature distribution maps of the upper phase change memory cells of a three-dimensional phase change memory include temperature distribution maps in plan view and cross view of phase change memory cells without elemental segregation and phase change memory cells with elemental segregation.
[0072] Depend on Figure 6 It can be seen that the bottom crystallization temperature of phase change memory cells where elemental segregation occurs is higher, while the top crystallization temperature is lower. (From...) Figure 7 It can be seen that the high temperature distribution of the phase change memory cell is mainly at the bottom. For phase change memory cells that have undergone element segregation, the high temperature at the bottom of the phase change memory layer, coupled with the high crystallization temperature at the bottom of the phase change material due to element segregation, has little impact on thermal crosstalk. That is, element segregation has little impact on the thermal crosstalk of the upper phase change memory cell.
[0073] In this application, for the second phase change memory cell 303, since the direction of the current is from the first conductive layer 201 to the second conductive layer 202, the direction of antimony (Sb) element segregation in the second phase change memory layer 307 is opposite to that in the first phase change memory layer 207. Therefore, the second phase change memory layer 307 is enriched with antimony (Sb) element at the top and less so at the bottom. Since the high-temperature distribution of the phase change memory 10 is mainly at the bottom, and the bottom phase change material of the second phase change memory layer 307 has less antimony (Sb), its crystallization temperature is higher, and it has little impact on the high-temperature distribution at the bottom of the second phase change memory layer 307. Therefore, the thermal crosstalk of the second phase change memory cell 303 will not worsen. Thus, the effect of element segregation on the thermal crosstalk of the second phase change memory cell 303 is not as significant as that on the thermal crosstalk of the first phase change memory cell 203. Therefore, the material of the second phase change storage layer 307 can be a conventional chalcogenide compound phase change material GST, such as GST225, GST124, etc.
[0074] Furthermore, the material of the second phase change storage layer 307 can be the same as that of the second phase change region 2072, both using conventional phase change materials such as GST225 and GST124. The first phase change region 2071 of the first phase change storage layer 207 uses materials such as GST225 or GST124 doped with germanium (Ge), indium (In), or nitrogen (N) elements to solve the problem of thermal crosstalk deterioration in the first phase change storage cell 203.
[0075] In some embodiments, please refer to Figure 8 The phase-change memory 10 includes a plurality of first conductive layers 201, a plurality of second conductive layers 202, a plurality of first phase-change memory cells 203 and a plurality of second phase-change memory cells 303 disposed on a substrate 100. The first conductive layers 201 and the second conductive layers 202 are stacked alternately along a first direction Z. The first phase-change memory cells 203 and the second phase-change memory cells 303 are stacked alternately along the first direction Z. The first phase-change memory cells 203 and the second phase-change memory cells 303 are respectively located between adjacent first conductive layers 201 and second conductive layers 202. In existing multilayer phase-change memory technologies, element segregation typically causes thermal crosstalk degradation in odd-numbered phase-change memory cells, while having little impact on even-numbered phase-change memory cells. Therefore, this application arranges the first phase-change memory cell 203 and the second phase-change memory cell 303 alternately stacked. For example, the odd-numbered phase-change memory cells relative to the substrate are set as the first phase-change memory cell 203, and the even-numbered phase-change memory cells are set as the second phase-change memory cell 303. The first phase-change memory cell 203 can improve the thermal crosstalk degradation caused by element segregation by improving the element distribution in the material of the first phase-change memory layer 207, while the second storage layer of the second phase-change memory cell 303 can use conventional phase-change materials.
[0076] For details, please refer to Figure 8Taking a four-layer phase-change memory as an example, the phase-change memory 10 includes a substrate 100, a first conductive layer 111 on the substrate 100, a first phase-change memory cell 121 on the first conductive layer 111, a second conductive layer 112 on the first phase-change memory cell 121, a second phase-change memory cell 122 on the second conductive layer 112, a third conductive layer 113 on the second phase-change memory cell 122, a third phase-change memory cell 123 on the third conductive layer 113, a fourth conductive layer 114 on the third phase-change memory cell 123, a fourth phase-change memory cell 124 on the fourth conductive layer 114, and a fifth conductive layer 115 on the fourth phase-change memory cell 124. Wherein, the second conductive layer 112 and the fourth conductive layer 114 are the first conductive layer 201; the first conductive layer 111, the third conductive layer 113, and the fifth conductive layer 115 are the second conductive layer 202; the first phase change memory unit 121 and the third phase change memory unit 123 are the first phase change memory unit 203; and the second phase change memory unit 122 and the fourth phase change memory unit 124 are the second phase change memory unit 303.
[0077] The first conductive layer 201 includes a plurality of first conductive lines 2011 arranged along the second direction Y. The first conductive lines 2011 extend along the third direction X, and the first conductive lines 2011 may be word lines WL. The second direction Y and the third direction X are perpendicular, and both the second direction Y and the third direction X are perpendicular to the first direction Z.
[0078] The second conductive layer 202 includes a plurality of second conductive lines 2021 arranged along a third direction X. The second conductive lines 2021 extend along a second direction Y. The second conductive lines 2021 may be bit lines BL.
[0079] The first phase change memory cell 203 includes a first bottom electrode 204, a first gate layer 205, a first intermediate electrode 206, a first phase change memory layer 207, a first top electrode 208, and a first linear barrier layer 209 covering the sidewalls of the first bottom electrode 204, the first gate layer 205, the first intermediate electrode 206, the first phase change memory layer 207, and the first top electrode 208, stacked sequentially along the first direction Z. The first phase change memory layer 207 includes a first phase change region 2071 and a second phase change region 2072, stacked along the first direction Z. The first phase change region 2071 includes a first phase change material, and the second phase change region 2072 includes a second phase change material. The first phase change material includes a second phase change material doped with a first element or a second element. The first element can be antimony (Sb), and the second element can be germanium (Ge), indium (In), or nitrogen (N). The second phase change material can be GST225 or GST124, but is not limited to these.
[0080] In other embodiments, the first phase change storage layer 207 may further include at least one third phase change region 2073, which is located between the first phase change region 2071 and the second phase change region 2072. The third phase change region 2073 may be a second phase change material including doping with a first element or a second element, wherein the content of the first element in the material of the third phase change region 2073 is less than the content of the first element in the material of the first phase change region 2071 and greater than the content of the first element in the material of the second phase change region 2072, or the content of the second element in the material of the third phase change region 2073 is less than the content of the second element in the material of the first phase change region 2071 and greater than the content of the second element in the material of the second phase change region 2072.
[0081] The second phase change memory cell 303 includes a second bottom electrode 304, a second gate layer 305, a second intermediate electrode 306, a second phase change memory layer 307, a second top electrode 308, and a second linear barrier layer 309 covering the sidewalls of the second bottom electrode 304, the second gate layer 305, the second intermediate electrode 306, the second phase change memory layer 307, and the second top electrode 308, arranged sequentially along the first direction Z. The second phase change memory layer 307 includes a second phase change material.
[0082] In the above embodiments, the materials of the first bottom electrode 204 and the second bottom electrode 304 can be the same, the materials of the first gate layer 205 and the second gate layer 305 can be the same, the materials of the first intermediate electrode 206 and the second intermediate electrode 306 can be the same, the materials of the first top electrode 208 and the second top electrode 308 can be the same, and the materials of the first linear barrier layer 209 and the second linear barrier layer 309 can be the same, but are not limited thereto.
[0083] It should be noted that the first conductive line 2011, the second conductive line 2021, the first bottom electrode 204, the first gate layer 205, the first intermediate electrode 206, the first top electrode 208, the first linear barrier layer 209, the second bottom electrode 304, the second gate layer 305, the second intermediate electrode 306, the second top electrode 308, and the second linear barrier layer 309 can be made of any material known in the art, and no restrictions are imposed here.
[0084] In this application, the phase change memory 10 can also be a structure containing three, five or more layers of phase change memory cells. Its structure and principle are similar to the phase change memory containing two or four layers of phase change memory cells described above, and will not be repeated here.
[0085] This application also provides a storage system, which includes a phase-change memory 10 and a controller. The phase-change memory 10 includes the phase-change memory 10 of any of the above embodiments. The controller is connected to the phase-change memory 10 and is used to control the phase-change memory 10 to store data. The phase-change memory 10 can perform data storage operations based on the control of the controller.
[0086] In summary, this application provides a phase change memory and a storage system. The phase change memory of this application includes at least a first phase change storage unit, the first phase change storage unit includes a first phase change storage layer, and the first phase change storage layer includes a first phase change region and a second phase change region stacked along the current direction. When the material of the first phase change region contains antimony (Sb), that is, when the antimony (Sb) content in the material of the first phase change region is greater than that in the material of the second phase change region, antimony (Sb) will move along the current direction when antimony (Sb) segregates in the first phase change storage layer. The antimony (Sb) in the material of the first phase change region will move into the material of the second phase change region. Eventually, the antimony (Sb) content in the material of the first phase change region and the antimony (Sb) content in the material of the second phase change region can be brought into balance. This application balances the effect of antimony (Sb) segregation in the first phase change storage layer by making the antimony (Sb) content in the material of the first phase change region greater than that in the material of the second phase change region, thereby improving the problem of further deterioration of thermal crosstalk caused by antimony (Sb) segregation. When the material in the first phase transition region contains the second element, the material in the first phase transition region is more stable because its crystallization temperature is higher than that of the material in the second phase transition region. This stability can limit the movement of antimony (Sb) elements, thereby improving the segregation process of antimony (Sb) elements and thus mitigating the problem of further deterioration of thermal crosstalk caused by antimony (Sb) element segregation.
[0087] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.
[0088] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.
[0089] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.
[0090] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.
Claims
1. A phase-change memory, characterized in that, include: At least one first conductive layer; At least one second conductive layer is stacked relative to the first conductive layer along a first direction; as well as At least one first phase change memory cell is disposed between the first conductive layer and the second conductive layer. The first phase change memory cell includes a first phase change memory layer, and the first phase change memory layer includes a first phase change region and a second phase change region. The second phase change region and the first phase change region are stacked along the first direction. The direction of the current in the phase change memory is from the first conductive layer to the second conductive layer, and the distance from the first phase change region to the first conductive layer is less than the distance from the second phase change region to the first conductive layer. Wherein, the material of the first phase transition region contains a first element, the content of the first element in the material of the first phase transition region is greater than the content of the first element in the material of the second phase transition region, and the first element is antimony. Alternatively, the material of the first phase transition region contains a second element, which causes the crystallization temperature of the material of the first phase transition region to be greater than the crystallization temperature of the material of the second phase transition region.
2. The phase-change memory according to claim 1, characterized in that, The second element is at least one of germanium, indium, or nitrogen.
3. The phase-change memory according to claim 1, characterized in that, When the material in the first phase transition region contains the first element, the material in the second phase transition region also contains the first element, and the content of the first element in the material in the first phase transition region is 1% to 15% higher than the content of the first element in the material in the second phase transition region.
4. The phase-change memory according to claim 1, characterized in that, When the material of the first phase transition region contains the second element, the material of the second phase transition region also contains the second element, and the content of the second element in the material of the first phase transition region is 1% to 25% higher than the content of the second element in the material of the second phase transition region.
5. The phase-change memory according to claim 1, characterized in that, The first phase change storage layer further includes at least one third phase change region, which is located between the first phase change region and the second phase change region; Wherein, the content of the first element in the material of the third phase transition region is less than the content of the first element in the material of the first phase transition region, but greater than the content of the first element in the material of the second phase transition region; Alternatively, the content of the second element in the material of the third phase transition region is less than the content of the second element in the material of the first phase transition region, but greater than the content of the second element in the material of the second phase transition region.
6. The phase-change memory according to claim 5, characterized in that, The first phase change storage layer includes a plurality of third phase change regions, which are stacked along the first direction, and the content of the first element in the material of the plurality of third phase change regions increases along the first direction relative to the first conductive layer.
7. The phase-change memory according to any one of claims 1 to 6, characterized in that, The material of the first phase transition region is a phase transition material with doped particles, and the element of the doped particles is either the first element or the second element; the material of the second phase transition region is a phase transition material, and the phase transition material includes a germanium-antimony-tellurium compound.
8. The phase-change memory according to claim 7, characterized in that, It also includes a substrate and at least one second phase change memory cell; along the first direction, the second conductive layer, the first phase change memory cell, the first conductive layer, and the second phase change memory cell are stacked on the substrate, and the distance from the first phase change memory cell to the substrate is less than the distance from the second phase change memory cell to the substrate; The second phase change memory unit includes a second phase change memory layer, and the material of the second phase change memory layer is the same as the material of the second phase change region.
9. The phase-change memory according to claim 8, characterized in that, The first phase-change memory cell further includes a first gate layer, which is located between the first phase-change memory layer and the first conductive layer, or between the first phase-change memory layer and the second conductive layer.
10. A storage system, characterized in that, include: The phase-change memory according to any one of claims 1 to 9; as well as A controller, connected to the phase change memory, is used to control the phase change memory to store data.