Superlattice phase change structure and method of manufacturing the same, phase change memory

Abstract

The embodiment of the present application provides a superlattice phase change structure, a manufacturing method thereof and a phase change memory, wherein the superlattice phase change structure comprises: a phase change material layer and a thermal barrier layer which are alternately stacked; a chemical general formula of a material of the phase change material layer is Sb x Te 1‑x , and 0.7 <= x < 1; and a material of the thermal barrier layer comprises a titanium subgroup telluride.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of semiconductor technology, and in particular to a super-lattice like (SLL) phase change structure, a manufacturing method thereof, and a phase change memory. BACKGROUND

[0002] Phase change memory (PCM) bridges the performance gap between dynamic random access memory (DRAM) and flash, and has the advantages of high-speed reading, high erasable times, non-volatility, small element size, low power consumption, strong anti-vibration and anti-radiation, and is widely used.

[0003] Unlike DRAM and flash that store data in the form of electric charge, PCM stores data by using the characteristics of crystalline and amorphous states of phase change materials, for example, using different electric pulses to induce rapid and reversible phase changes between amorphous and crystalline states of phase change materials. Using current heating, the phase change material is converted from an amorphous state to a crystalline state, which is called a SET (set) operation; or the phase change material is converted from a crystalline state to an amorphous state, which is called a RESET (reset) operation. The change in the state of the phase change material can represent a bit of data "0" or "1".

[0004] However, the phase change material in the related art has problems of low SET speed, large RESET current, and small cycle times, which limits the performance of the PCM. SUMMARY

[0005] Therefore, embodiments of the present application provide a super-lattice phase change structure, a manufacturing method thereof, and a phase change memory.

[0006] According to a first aspect of embodiments of the present application, a super-lattice phase change structure is provided, comprising:

[0007] The phase change material layer and the thermal barrier layer are alternately stacked; the chemical formula of the material of the phase change material layer is Sb x Te 1-x , and 0.7≤x<1; the material of the thermal barrier layer includes titanium sub-group tellurides.

[0008] In the above solution, the material of the phase change material layer includes at least one of antimony and a tellurium-antimony compound mixture; the material of the thermal barrier layer includes at least one of titanium telluride, zirconium telluride, or hafnium telluride.

[0009] In the scheme, the material of the phase change material layer comprises Sb7Te3; and the material of the thermal barrier layer comprises TiTe2.

[0010] In the scheme, the phase change material layer comprises a sub phase change material layer and a seed material layer which are stacked, the material of the sub phase change material layer comprises Sb2Te3, and the material of the seed material layer comprises Sb; and the material of the thermal barrier layer comprises TiTe2.

[0011] In the scheme, the superlattice phase change structure further comprises a complementary phase change material layer; and the material of the complementary phase change material layer comprises GeTe.

[0012] According to another aspect of the embodiments of the present application, a phase change memory is provided, comprising:

[0013] A phase change memory cell comprising the superlattice phase change structure.

[0014] In the scheme, the phase change memory cell further comprises:

[0015] A first electrode disposed below the superlattice phase change structure, and a second electrode disposed above the superlattice phase change structure; and

[0016] A gating layer and a third electrode which are stacked above the second electrode or below the first electrode.

[0017] According to still another aspect of the embodiments of the present application, a manufacturing method of a superlattice phase change structure is provided, comprising:

[0018] Forming phase change material layers and thermal barrier layers which are alternately stacked; the material of the phase change material layer has a chemical formula of Sb x Te 1-x and 0.7≤x<1; and the material of the thermal barrier layer comprises a titanium subgroup telluride.

[0019] In the scheme, the material of the phase change material layer comprises a tellurium antimony compound; and the forming of the phase change material layer comprises:

[0020] The phase change material layer is formed by in-situ doping of Sb element while depositing the phase change material layer through an in-situ doping process.

[0021] In the scheme, the material of the phase change material layer comprises a mixture of antimony and a tellurium antimony compound; and the phase change material layer comprises a sub phase change material layer and a seed material layer.

[0022] The forming of the phase change material layer comprises:

[0023] The sub phase change material layer is formed; and the material of the sub phase change material layer comprises Sb2Te3.

[0024] forming the seed material layer on the sub-phase change material layer; the material of the seed material layer comprises Sb.

[0025] The application provides a superlattice phase change structure, a manufacturing method thereof and a phase change memory. x Te 1-x , and 0.7≤x<1; the material of the thermal barrier layer comprises titanium subgroup telluride. x Te 1-x The superlattice structure is alternately stacked by Sb x Te 1-x with a high percentage of Sb, which can increase the crystallization speed of Sb x Te 1-x as the phase change material layer, thereby increasing the SET speed of the phase change memory; meanwhile, the titanium subgroup telluride as the thermal barrier layer has a low thermal conductivity, which reduces the RESET current of the phase change memory in the process of transforming from a crystalline state to an amorphous state. x Te 1-x The energy loss in the process of transforming from a crystalline state to an amorphous state is reduced, thereby reducing the RESET current of the phase change memory. x Te 1-x The titanium subgroup telluride is alternately separated in space and does not react with Sb x Te 1-x and can hinder the element migration of Sb x Te 1-x , thereby increasing the cycle times of the phase change memory. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A partial three-dimensional architecture schematic diagram of a phase change memory is provided in the application.

[0027] Figures 2a to 2c Some schematic diagrams of superlattice phase change structures are provided in the application.

[0028] Figure 3 A cross-sectional schematic diagram of a phase change memory cell is provided in the application.

[0029] Figure 4 A cross-sectional schematic diagram of a phase change memory is provided in the application. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be further described in detail below with reference to the drawings and embodiments. Although the exemplary implementation methods of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the implementation described herein. On the contrary, these implementations are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0031] In the following paragraphs, embodiments of the present application will be described in more detail with reference to the accompanying drawings. The advantages and features of the present application will be more apparent from the following description and claims. It should be noted that the drawings are very simplified and use non-precise proportions, only for the purpose of facilitating, clarifying and assisting in the description of the embodiments of the present application.

[0032] It can be understood that the meanings of "on", "above" and "over" of the present application should be interpreted in the broadest way, so that "on" not only means the meaning of "on" with no intervening features or layers therebetween (i.e. directly on), but also includes the meaning of "on" with intervening features or layers therebetween.

[0033] In embodiments of the present application, the term "A is connected to B" includes the case where A and B are connected to each other with A and B in contact with each other, or the case where A and B are connected to each other with other components interposed therebetween and A not in contact with B.

[0034] In embodiments of the present application, the terms "first", "second", and the like are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence.

[0035] In embodiments of the present application, the term "layer" refers to a portion of material that includes a region having a thickness. A layer can extend over the entirety of an underlying or overlying structure, or can have a scope that is less than the scope of an underlying or overlying structure. Further, a layer can be a region of a homogenous or inhomogenous continuous structure that has a thickness that is less than the thickness of the continuous structure. For example, a layer can be located between a top surface and a bottom surface of a continuous structure, or the layer can be between any horizontal pair of planes at the top surface and the bottom surface of the continuous structure. A layer can extend horizontally, vertically, and / or along an inclined surface. A layer can include multiple sub-layers. For example, an interconnect layer can include one or more conductor and contact sub-layers (in which interconnect lines and / or via contacts are formed), and one or more dielectric sub-layers.

[0036] It should be noted that the technical solutions described in the embodiments of the present application can be combined arbitrarily without conflict.

[0037] For ease of description, the Z-axis in the embodiments of the present application and the accompanying drawings represents the direction in which the stacked layers are stacked, and the X-axis and the Y-axis represent two orthogonal directions perpendicular to the stacking direction.

[0038] Three-dimensional phase change memory stores data based on the resistance change of the phase change material of the memory cell (e.g., in a high resistance state or a low resistance state). The phase change memory has a transistor-free cross-point architecture, which places the memory cell at the intersection of perpendicular conductors, including word lines (WL) and bit lines (BL) that intersect each other perpendicularly, which are generally composed of 20 nm / 20 nm line / space (L / S) after a patterning process.

[0039] Unlike DRAM and flash that store data in the form of charge, the phase change memory stores data by using the characteristics of the crystalline and amorphous states of the phase change material, which is induced by different electrical pulses to make a fast and reversible phase change between the amorphous state and the crystalline state. The phase change material is heated by using current to convert from the amorphous state to the crystalline state, which is called a SET (set) operation; or to convert from the crystalline state to the amorphous state, which is called a RESET (reset) operation. The change of the state of the phase change material can represent a bit of data "0" or "1".

[0040] There is a certain relationship between the time, temperature, and current when the phase change memory undergoes a phase change. In the write operation mode, if the data is "1", the word line WL is selected, and the write current is injected into the phase change memory through the bit line BL to heat the phase change material. The temperature of the phase change material is greater than the melting temperature, and the phase change material becomes amorphous. At this time, the required current (Amorphizing RESET Pulse) is the RESET current of the phase change, and then the injected current is quickly reduced, so that the temperature of the phase change material quickly decreases, and the phase change material cannot be crystallized in time, and thus is locked in the amorphous state, in a high resistance state, and the signal "1" is stored in the amorphous state. If the data is "0", the word line WL is selected, and the write current (Crystallization SET Pulse) is injected into the phase change memory through the bit line BL to heat the phase change material. The temperature of the phase change material is greater than the crystallization temperature and less than the melting temperature, and is maintained for a period of time, and the phase change material becomes crystalline. The phase change material is locked in the crystalline state, in a low resistance state, and the signal "0" is stored in the crystalline state.

[0041] Figure 1 is a partial three-dimensional architecture schematic diagram of a phase change memory provided by an embodiment of the present application. As shown in FIG. 1, the phase change memory includes a plurality of memory cells 100, a plurality of word lines WL, and a plurality of bit lines BL. The memory cells 100 are arranged in a matrix form, and each memory cell 100 is located at the intersection of a word line WL and a bit line BL. The memory cells 100 are connected to the word lines WL and the bit lines BL through a plurality of vertical conductors 200. Figure 1As shown, the phase-change memory 10 includes a first address line 101, a first phase-change memory unit 102, a second address line 103, a second phase-change memory unit 104, and a third address line 105 stacked sequentially from bottom to top. The first phase-change memory unit 102 and the second phase-change memory unit 104 each include a first electrode 1021, a gating element 1022, a second electrode 1023, a phase-change memory element 1024, and a third electrode 1025 stacked sequentially from bottom to top. The phase-change memory can store data by heating and quenching the phase-change memory element 1024, causing it to switch between an amorphous and crystalline state, and then utilizing the difference in resistivity between the amorphous and crystalline states.

[0042] from Figure 1 As can be seen, the first address line 101 is parallel to the third address line 105, and both the first address line 101 and the third address line 105 are perpendicular to the second address line 103. Simultaneously, the first phase-change memory cell 102 is perpendicular to both the first address line 101 and the second address line 103, and the second phase-change memory cell 104 is perpendicular to both the second address line 103 and the third address line 105. The first address line 101 and the third address line 105 can be used as bit lines, and the second address line 103 can be used as a word line. In practical applications, the selection of phase-change memory cells connected to both the selected word line and the selected bit line is achieved by activating the selected word line and the selected bit line.

[0043] In related technologies, the phase change material (PCT) of the phase change memory cells in phase change memories (PCMs) is generally based on gas-silicon-to-carbon (GST) materials, such as Ge₂Sb₂Te₅. However, the slow crystallization (transformation from amorphous to crystalline state) speed of GST-based PCTs results in a SET operation speed of approximately several hundred nanoseconds, limiting the data write rate of PCMs. Furthermore, GST-based PCTs require milliampere-level currents to melt the crystalline phase (transformation from crystalline to amorphous state), leading to excessively high RESET operation currents and power consumption. On the other hand, the number of reversible phase transitions (reversible phase transitions between amorphous and crystalline states) in GST-based PCTs is limited, resulting in a low cycle life for PCMs. In other words, the PCTs in related technologies suffer from low SET speed, high RESET current, and low cycle life, which limit the performance of PCMs.

[0044] To address at least one of the aforementioned problems, embodiments of this application provide a superlattice phase change structure and its manufacturing method, as well as a phase change memory. The novel superlattice structure material used in this application can improve the SET speed of the phase change memory, reduce the RESET current, and increase the cycle life of the phase change memory, thereby enhancing the performance of the phase change memory.

[0045] Superlattice structure is defined as a periodic structure of two materials which are alternately stacked and grown, and the thickness of each layer of material is below 100 nm. The movement of phonon (a kind of quasi-particle, which is used to describe the energy quantum of the regularity of the thermal vibration of atoms in a crystal, i.e. lattice vibration) along the stacking direction will produce oscillation. It can be understood that the superlattice structure material can be a multilayer film of two different components alternately grown in a thin layer of less than one nanometer to tens of nanometers and strictly periodic. In fact, it is a specific form of layered fine composite material.

[0046] The multilayer film structure introduces a certain number of interfaces into the material. Under the action of interface scattering, the movement of phonon along the stacking direction is hindered, and additional interface phonon impedance is generated. In a semiconductor, phonon is the main carrier of heat flow, and the macroscopic thermal conductivity of the semiconductor material is mainly determined by phonon. Therefore, the interface phonon impedance will produce obvious interface thermal resistance, thereby reducing the thermal conductivity of the material. The reduction of the thermal conductivity of the material means that the ability of the material to diffuse heat will be greatly enhanced. That is, the reduction of the thermal conductivity will improve the thermal performance of the multilayer phase change material, such as the thermal stability of the material and the like. By using the characteristics of the superlattice structure, the superlattice structure can be used to manufacture a storage unit of a phase change memory to improve the performance of the storage unit.

[0047] The embodiment of the present application provides a superlattice phase change structure, comprising:

[0048] The phase change material layer and the thermal resistance barrier layer are alternately stacked. The chemical formula of the material of the phase change material layer is Sb x Te 1-x , and 0.7≤x<1. The material of the thermal resistance barrier layer comprises a titanium subgroup telluride. It should be noted that in the embodiment of the present application, "Sb x Te 1-x " includes any material that can be represented by the general formula Sb x Te 1-x , and in the range of 0.7≤x<1, the specific stoichiometric ratio between Sb and Te is not limited, wherein x can be understood as the atomic percentage of Sb element in Sb x Te 1-x , and x cannot be understood as the atomic number of Sb element in Sb x Te 1-x . That is, Sb x Te 1-xThe proportion of Sb element can be selected in the range of 0.7≤x<1. For example, the material of the phase change material layer can be Sb7Te3, which means the stoichiometric ratio between Sb element and Te element in Sb7Te3 is 7:3, and the proportion of Sb element in Sb7Te3 is 0.7. It can be understood that Sb x Te 1-x When x is 0.7.

[0049] Here, the phase change material layer and the thermal barrier layer can have the same or similar crystal structure, such as they can both have hexagonal lattice and the lattice constants are close to each other. The material of the multilayer phase change structure formed by the phase change material layer and the thermal barrier layer alternately stacked has the same crystal structure, and is formed into a superlattice phase change structure.

[0050] Here, the titanium subgroup telluride as the thermal barrier layer, Sb x Te 1-x as the phase change material layer, Sb x Te 1-x and the titanium subgroup telluride alternately stacked form a superlattice structure, which improves the SET speed of the phase change memory, reduces the RESET current of the phase change memory, and increases the cycle number of the phase change memory. Specifically:

[0051] In the first aspect, the titanium subgroup telluride and Sb x Te 1-x have the same or similar crystal structure, and the adjacent layers form a van der Waals layer by van der Waals force. In Sb x Te 1-x , the titanium subgroup telluride can act as a crystal seed to accelerate the crystallization process of Sb x Te 1-x and improve the phase change rate thereof;

[0052] In the second aspect, 0.7≤x<1 in Sb x Te 1-x , that is, the proportion of Sb element in the phase change material layer is relatively high. The high proportion of Sb element can improve the crystallization speed of Sb x Te 1-x , thereby accelerating the SET speed of the phase change memory;

[0053] In the third aspect, compared with Sb x Te 1-x , the titanium subgroup telluride has a lower thermal conductivity and a higher electrical conductivity. In this way, the titanium subgroup telluride can reduce the Sb x Te 1-xThe energy loss in the process of transforming from the crystalline state to the non-crystalline state, thereby reducing the RESET current of the phase change memory, in addition, the titanium subgroup telluride and Sb x Te 1-x The spatial separation is also conducive to reducing the RESET current.

[0054] In the fourth aspect, the titanium subgroup telluride has a stable hexagonal crystal structure (the titanium subgroup element is located at the center of the hexagonal lattice) in both the crystalline state and the non-crystalline state, and the titanium subgroup telluride can maintain structural stability and is not prone to reacting with Sb x Te 1-x The reaction occurs, which plays a role in delaying the relaxation of the superlattice phase change structure and hindering the migration of material elements in the phase change material layer, thereby inhibiting signal drift of the phase change memory, reducing signal noise of the phase change memory, and increasing the cycle number of the phase change memory.

[0055] In some embodiments, the material of the phase change material layer includes at least one of antimony and a tellurium-antimony compound. Here, the material of the phase change material layer can include a mixture of antimony and a tellurium-antimony compound. The mixture of antimony and a tellurium-antimony compound can be a mixture formed by independent crystallization of single-phase antimony and single-phase tellurium-antimony compound, which can be understood as a mixture between the crystal structures of single-phase antimony and single-phase tellurium-antimony compound. In the mixture, the phase change material layer can include a seed material layer and a sub-phase change material layer arranged in layers; the material of the seed material layer can be single-phase antimony, and the material of the sub-phase change material layer can be single-phase tellurium-antimony compound. Here, the positions of the seed material layer and the sub-phase change material layer can be interchanged.

[0056] Exemplarily, the mixture of antimony and a tellurium-antimony compound can be a mixture of Sb and Sb2Te3. At this time, the phase change material layer can include Sb and Sb2Te3 arranged in layers.

[0057] Here, the material of the phase change material layer can include a tellurium-antimony compound. At this time, the tellurium-antimony compound can be a eutectic phase. Exemplarily, the tellurium-antimony compound can be Sb7Te3, which is obtained by simultaneously solidifying liquid-phase Sb7Te3 into seed Sb and seed Sb2Te3 to form a mixture of two phases of Sb and Sb2Te3. The mixing degree of the eutectic phase can be understood as being between the mixing between crystal structures and the mixing within crystal structures.

[0058] In some embodiments, the material of the thermal barrier layer includes at least one of titanium telluride, zirconium telluride, or hafnium telluride.

[0059] In some embodiments, the material of the thermal barrier layer includes titanium telluride, which specifically can include at least one of TiTe, TiTe2, Ti5Te8, Ti2Te3. Preferably, the material of the thermal barrier layer includes TiTe2.

[0060] In some embodiments, the material of the thermal barrier layer includes zirconium telluride, which specifically can include at least one of ZrTe, ZrTe2, Zr5Te8, Zr2Te3.

[0061] In some embodiments, the material of the thermal barrier layer includes hafnium telluride, which specifically can include at least one of HfTe, HfTe2, Hf5Te8, Hf2Te3.

[0062] Figures 2a to 2c Some schematic diagrams of superlattice phase change structures provided in embodiments of the present application. Figures 2a to 2c As shown, the superlattice structures 210a, 210b, 210c are formed by alternately stacking the phase change material layers and the thermal barrier layers.

[0063] In some embodiments, the phase change material layer 2212 can be disposed on the thermal barrier layer 2211, and the thermal barrier layer 2211 and the phase change material layer 2212 constitute a periodic stack, and a plurality of periodic stacks are further disposed on the stack. According to actual needs, a superlattice structure with a plurality of periodic stacks can be provided, and it can be understood that the upper and lower sides of the superlattice structure are respectively the thermal barrier layer 2211 and the phase change material layer 2212.

[0064] In the above embodiments, the positions of the thermal barrier layer and the phase change material layer in each periodic stack can be interchanged, that is, the phase change material layer 2212 can be disposed on the thermal barrier layer 2211. The number of the plurality of periodic stacks can be 2-100, and the thickness of each periodic stack can be 1-100 nm. It should be noted that the number of the plurality of periodic stacks and the thickness of each phase change material layer or each thermal barrier layer can be adjusted according to actual process needs.

[0065] In some specific embodiments, the material of the phase change material layer includes Sb7Te3, and the material of the thermal barrier layer includes TiTe2.

[0066] As Figure 2aAs shown, TiTe2 is used as the thermal barrier layer, Sb7Te3 is used as the phase change material layer, and the superlattice structure 210a is formed by alternately stacking Sb7Te3 and TiTe2. In this example, TiTe2 is located above Sb7Te3. It should be noted that in some other examples, TiTe2 can be located below Sb7Te3, Sb7Te3 can be another tellurium-antimony compound with a higher Sb content, and TiTe2 can be another titanium subgroup telluride.

[0067] In some specific embodiments, the phase change material layer includes a plurality of sub-phase change material layers and a plurality of seed material layers, the material of the sub-phase change material layers includes Sb2Te3, and the material of the seed material layers includes Sb; and the material of the thermal barrier layer includes TiTe2.

[0068] As shown in FIG. 21b, the superlattice structure 210b is formed by alternately stacking the phase change material layer and the thermal barrier layer. In this example, the phase change material layer includes a seed material layer 2212-0 and a sub-phase change material layer 2212-1, and the thermal barrier layer includes a thermal barrier layer 2211. Figure 2b As shown in FIG. 21b, the superlattice structure 210b is formed by alternately stacking the phase change material layer and the thermal barrier layer. In this example, the phase change material layer includes a seed material layer 2212-0 and a sub-phase change material layer 2212-1, and the thermal barrier layer includes a thermal barrier layer 2211.

[0069] As shown in FIG. 21b, the superlattice structure 210b is formed by alternately stacking the phase change material layer and the thermal barrier layer. In this example, the phase change material layer includes a seed material layer 2212-0 and a sub-phase change material layer 2212-1, and the thermal barrier layer includes a thermal barrier layer 2211. Figure 2b As shown in FIG. 21b, the superlattice structure 210b is formed by alternately stacking the phase change material layer and the thermal barrier layer. In this example, the phase change material layer includes a seed material layer 2212-0 and a sub-phase change material layer 2212-1, and the thermal barrier layer includes a thermal barrier layer 2211.

[0070] It should be noted that the sub-phase change material layer 2212-1 and the seed material layer 2212-0 can be interchanged, and in some other examples, the sub-phase change material layer 2212-1 can be located above the seed material layer 2212-0.

[0071] It should be noted that the sub-phase change material layer 2212-1 can include a tellurium-antimony compound with a higher Sb content, and in some other examples, the material of the sub-phase change material layer 2212-1 can further include Sb7Te3 or another tellurium-antimony compound.

[0072] In some specific embodiments, the superlattice phase change structure further includes a supplemental phase change material layer, and the material of the supplemental phase change material layer includes GeTe. As shown in FIG. 21c, the superlattice structure 210c is formed by alternately stacking the phase change material layer and the thermal barrier layer. In this example, the phase change material layer includes a seed material layer 2212-0, a sub-phase change material layer 2212-1, and a supplemental phase change material layer 2212-2, and the thermal barrier layer includes a thermal barrier layer 2211. Figure 2cAs shown, TiTe2 is used as the thermal barrier layer 2211, Sb7Te3 is used as the phase change material layer 2212, and GeTe is used as the supplemental phase change material layer 2213. It should be noted that the supplemental phase change material layer 2213 is stacked with the thermal barrier layer 2211 and the phase change material layer 2212. In some other examples, the phase change material layer 2212 can include a tellurium-antimony compound with a higher proportion of Sb.

[0073] In some specific embodiments, the phase change material layer 2212 can further include Sb2Te3. In this case, TiTe2 is still used as the thermal barrier layer 2211, and GeTe is used as the supplemental phase change material layer 2213.

[0074] It can be understood that the introduction of the supplemental phase change material layer can introduce some advantages of Ge element in the phase change process.

[0075] In some embodiments, the phase change material layer further includes a doping element, which can include a transition metal element.

[0076] Here, the transition metal element can be at least one of chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), magnesium (Mg), cadmium (Cd), indium (In), hafnium (Hf), titanium (Ti), tantalum (Ta), and tungsten (W). In some embodiments, the doping amount of the doping element can be controlled in the range of 0-10% of the atomic percentage, where the atomic percentage is the ratio of the number of atoms of the doping element in the phase change material layer to the total number of atoms of all elements in the phase change material layer. By doping a certain amount of transition metal element in the phase change material layer, the crystallization speed, fatigue characteristics, and other properties of the material of the phase change material layer can be adjusted and optimized.

[0077] In some other embodiments, the doping element can also be a non-metal material element, including at least one of C, N, Si, and O. By doping a certain amount of non-metal material element in the phase change material layer, the thermal stability of the phase change material layer can be improved.

[0078] By doping a certain amount of doping element in the phase change material layer Sb x Te 1-x , the chemical formula of the material of the phase change material layer with the doping element is (Sb x Te 1-x ) 1-y R ywherein R includes a transition metal element or a non-metal material element, and 0.7≤x≤0.9, 0 x Te 1-x ) 1-y R y The material of the phase-change material layer with the doping element has a high SET speed, a low RESET current, and a large number of cycles, as compared to the material of the phase-change material layer without the doping element.

[0079] In the embodiments of the present application, Sb x Te 1-x are alternately stacked to form a superlattice structure, wherein Sb x Te 1-x has a higher percentage of Sb, and the higher percentage of Sb can increase the crystallization speed of Sb x Te 1-x as the phase-change material layer, thereby increasing the SET speed of the phase-change memory; meanwhile, the titanium subgroup telluride, as a thermal barrier layer, has a low thermal conductivity, which reduces the RESET current of Sb x Te 1-x in the process of transforming from a crystalline state to an amorphous state, thereby reducing the RESET current of the phase-change memory; furthermore, the titanium subgroup telluride and Sb x Te 1-x are alternately separated in space, and the titanium subgroup telluride does not react with Sb x Te 1-x and can hinder the element migration of Sb x Te 1-x , thereby increasing the number of cycles of the phase-change memory.

[0080] Figure 3 Some cross-sectional schematic diagrams of phase-change memory cells are provided in the embodiments of the present application.

[0081] In yet another aspect of the embodiments of the present application, a phase-change memory is provided, comprising:

[0082] A phase-change memory cell, which at least includes the superlattice phase-change structure described in the embodiments of the present application. The superlattice phase-change structure is described above and will not be repeated here.

[0083] In some embodiments, the phase-change memory cell further comprises:

[0084] a first electrode arranged below the superlattice phase-change structure, and a second electrode arranged above the superlattice phase-change structure; and

[0085] a gating layer, a third electrode, which are stacked above the second electrode or below the first electrode.

[0086] As Figure 3 shown, the phase change memory cell 200 includes a third electrode 241, a gating layer 231, a first electrode 251, the superlattice phase change structure 221, a second electrode 261, which are stacked in sequence. It can be understood that the phase change memory cell 200 can also include a first electrode 251, the superlattice phase change structure 221, a second electrode 261, a gating layer 231, a third electrode 241, which are stacked in sequence.

[0087] It should be noted that the first electrode 251, the second electrode 261 and the third electrode 241 in the phase change memory cell represent electrode layers, the materials included in the electrode layers can be the same or different, and different reference numerals are only used to distinguish the different positions of the electrode layers, and do not necessarily describe a specific order or sequence. The material of the electrode layer can include amorphous carbon, such as alpha-phase carbon. The electrode layer is used to conduct an electrical signal.

[0088] The material of the gating layer 231 can include an Ovonic Threshold Switching (OTS) material, such as Zn a Te b , Ge a Te b , Nb a O b or Si a As b Te c , etc., wherein a, b, and c represent stoichiometric numbers.

[0089] Figure 4 Some cross-sectional schematic diagrams of phase change memories provided by embodiments of the present application.

[0090] As Figure 4 shown, the phase change memory cell 200 includes a third electrode 241, a gating layer 231, a first electrode 251, the superlattice phase change structure 221, a second electrode 261, which are stacked in sequence. It can be understood that the phase change memory cell 200 can also include a first electrode 251, the superlattice phase change structure 221, a second electrode 261, a gating layer 231, a third electrode 241, which are stacked in sequence. Figure 4 The lower part of the figure is a cross-sectional view of a one-layer stack structure, Figure 4The upper part of the figure is another layer stack structure cross-sectional view, which can be seen that the phase change memory cell includes: bottom cell structure and top cell structure; wherein the phase change memory cell includes: bottom bit line 201, top bit line 202 in the same plane above the bottom bit line 201, bottom word line 211, top word line 212 in the same plane above the bottom word line 211, bottom cell structure 291 located between the bottom bit line 201 and the bottom word line 211, and top cell structure 292 located between the top bit line 202 and the top word line 212. In practical applications, the word line (including the bottom word line 211 and the top word line 212) can be a common word line for the bottom cell structure and the top cell structure.

[0091] As shown in Figure 4 some embodiments, the bottom cell structure 291 includes the bottom bit line 201, the bottom bottom electrode 241, the bottom gating layer 231, the bottom middle electrode 251, the bottom storage unit 221, the bottom top electrode 261, and the bottom word line 211 stacked in sequence; similarly, the top cell structure 292 includes the top word line 212, the top bottom electrode 242, the top gating layer 232, the top middle electrode 252, the top storage unit 222, the top top electrode 262, and the top bit line 202 stacked in sequence. In other embodiments, the bottom storage unit 221 further includes a bottom adhesion layer 271, 281 between the bottom middle electrode 251 and the bottom top electrode 261, respectively; similarly, the top storage unit 222 further includes a top contact electrode 272, 282 between the top middle electrode 252 and the top top electrode 262, respectively. It should be noted that the bottom word line 211 and the top word line 212 can be integrated as a common word line for the bottom cell structure and the top cell structure.

[0092] It should be noted that the bottom storage unit 221 and the top storage unit 222 can be understood as the superlattice phase change structure 200a, 200b, 200c provided by the embodiments of the present application (refer to the above Figures 2a to 2c ), which is described above and will not be repeated here. The bottom cell structure 291 and the top cell structure 292 can be understood as the phase change memory cell 200 provided by the embodiments of the present application (refer to the above Figure 3 ), which is described above and will not be repeated here.

[0093] The material of the adhesion layer (including the bottom adhesion layer 271, 281, and the top adhesion layer 272, 282) includes a conductive material. The conductive material includes but is not limited to tungsten (W).

[0094] The material of the bit lines (including the bottom bit line 201 and the top bit line 202) and the word lines (including the bottom word line 211 and the top word line 212, which can be integrated as a common word line) includes a conductive material. The conductive material includes, but is not limited to, tungsten, cobalt, copper (Cu), aluminum, polysilicon, doped silicon, conductive nitride, or any combination thereof. The bit lines and the word lines can have the same conductive material or different conductive materials.

[0095] In practical applications, Figure 4 The medium layers 271-1 to 271-6 required are also shown in the figure. It can be understood that the medium layers 271-1 to 271-4 are used to electrically isolate adjacent phase change memory cells 200, and to electrically isolate each row of bit lines arranged along the first direction X. The medium layers 271-5 to 271-6 are used to electrically isolate adjacent phase change memories 20. The material of the medium layers 271-1, 271-3, and 271-5 includes, but is not limited to, silicon nitride, silicon oxynitride, silicon carbide, silicon dioxide, or any combination thereof.

[0096] It should be noted that the bit lines (including the bottom bit line 201 and the top bit line 202) extend along the X direction, the word lines (including the bottom word line 211 and the top word line 212) extend along the Y direction, and the phase change memory cells are stacked along the Z direction.

[0097] The embodiment of the present application also provides a manufacturing method of the superlattice phase change structure, including:

[0098] The phase change material layer and the thermal barrier layer are alternately stacked; the chemical formula of the phase change material layer is Sb x Te 1-x and 0.7≤x<1; the thermal barrier layer includes a titanium subgroup telluride.

[0099] In some embodiments, the material of the phase change material layer includes a tellurium antimony compound; the phase change material layer is formed; and the phase change material layer is formed by an in-situ doping process to dope the Sb element in-situ while depositing the phase change material layer.

[0100] An in-situ doping process is employed to deposit a phase change material layer doped with Sb. This can be achieved using processes including, but not limited to, physical vapor deposition (PVD), chemical vapor deposition (CVD), or atomic layer deposition (ALD). During the deposition of the phase change material layer, a gas containing Sb is introduced, thus incorporating Sb simultaneously with the deposition of the phase change material layer. The incorporation of Sb increases the proportion of Sb in the phase change material layer, thereby enhancing its doping properties. x Te 1-x In the case of 0.7 ≤ x < 1.

[0101] In some embodiments, the phase change material layer comprises a mixture of antimony and antimony telluride compounds; the phase change material layer comprises a sub-phase change material layer and a seed material layer;

[0102] The formation of the phase change material layer includes:

[0103] The subphase change material layer is formed; the material of the subphase change material layer includes Sb₂Te₃.

[0104] The seed material layer is formed on the subphase change material layer; the material of the seed material layer includes Sb.

[0105] For example, the seed material layer and the subphase change material layer can be formed by a deposition process. Here, the deposition process includes, but is not limited to, PVD, CVD, or ALD processes. Depositing the seed material layer first on the heat barrier layer and then depositing the subphase change material layer on the seed material layer results in better crystallization properties of the subphase change material layer compared to a deposition method that directly deposits the subphase change material layer on the heat barrier layer.

[0106] The superlattice phase transition structure manufactured by the method provided in this application is similar to the superlattice phase transition structure in the above embodiments. For technical features not disclosed in detail in this application, please refer to the above embodiments for understanding. Here, they will not be repeated.

[0107] It should be understood that every feature, structure, or characteristic described in relation to an embodiment is within the scope of at least one embodiment of the present application. Therefore, whenever a particular feature, structure, or characteristic is described in relation to an embodiment, it is intended to convey that it is included in at least one embodiment. Thus, the appearances of "in one embodiment" or "in an embodiment" are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should also be understood that, unless specifically stated otherwise, the order of steps presented in any process described herein can depend on the specific application of the method. Thus, the embodiments of the present application should not be construed that the process must be performed in the order presented, unless specifically stated otherwise. Embodiments of the present application can be implemented in hardware, software, firmware, or a combination thereof. Embodiments of the present application can be implemented in one or more computer programs or code that can be executable on a processor-based system affixed in a desired system. Embodiments of the present application can also be implemented using specially designed hardware, using a combination of specially designed hardware and software, or using software operating on conventional hardware. Embodiments of the present application can also be implemented using a combination of software and firmware.

[0108] The methods disclosed in the several method embodiments provided by the present application can be combined in any suitable manner, without conflict, to obtain new method embodiments.

[0109] The above description is merely illustrative of the application, and the scope of the application is not limited thereto. Any modifications and changes within the scope of the application will be readily apparent to those skilled in the art. Therefore, the scope of the application is not limited to the specific embodiments described herein, but only by the claims that follow, the intent being that equivalents, within the scope of the following claims, are to be substituted for any features not specifically recited in the claims.

Claims

1. A superlattice phase change structure, characterized in that, Comprising: a plurality of periodic stacks; the periodic stack comprises a complementary phase change material layer, a thermal barrier layer and a phase change material layer arranged in a stack; the material of the complementary phase change material layer comprises GeTe; the chemical formula of the material of the phase change material layer is Sb x Te 1-x , and 0.7 < x < 1; the material of the thermal barrier layer comprises at least one of titanium telluride, zirconium telluride or hafnium telluride; wherein the phase change material layer comprises a sub-phase change material layer and a seed material layer arranged in a stack; the seed material layer is arranged on the thermal barrier layer, and the material of the seed material layer comprises Sb; the sub-phase change material layer is arranged on the seed material layer, and the material of the sub-phase change material layer comprises Sb2Te3, Sb7Te3 or other tellurium-antimony compound with a higher proportion of Sb. The phase change material layer further comprises a doping element; the doping element comprises a non-metal material element; a chemical general formula of a material of the phase change material layer is (Sb x Te1 x )1 y R y , R comprises a non-metal material element, and 0.7 2. The superlattice phase change structure of claim 1, wherein, The material of the seed material layer comprises single crystal phase antimony; the material of the sub-phase change material layer comprises single crystal phase tellurium antimony compound.

3. A phase change memory, characterized by, Comprising: The phase change memory cell further comprises:

4. The phase change memory of claim 3, wherein, A first electrode disposed below the superlattice phase change structure, a second electrode disposed above the superlattice phase change structure; and A gating layer disposed above the second electrode or below the first electrode, a third electrode. Comprising:

5. A method of fabricating a superlattice phase change structure, characterized by, Wherein, forming the phase change material layer comprises disposing a seed material layer on the thermal barrier layer, the material of the seed material layer comprises Sb; disposing a sub-phase change material layer on the seed material layer, the material of the sub-phase change material layer comprises Sb2Te3, Sb7Te3 or other tellurium antimony compound with higher Sb proportion; forming a plurality of periodic stacks; the periodic stacks comprising a stack of a complementary phase change material layer, a thermal barrier layer, and a phase change material layer; the material of the complementary phase change material layer comprising GeTe; the material of the phase change material layer having a chemical formula of Sb x Te 1-x and 0.7 < x < 1; the material of the thermal barrier layer comprising at least one of titanium telluride, zirconium telluride, or hafnium telluride; ​ The phase change material layer further comprises a doping element; the doping element comprises a non-metal material element; a chemical general formula of a material of the phase change material layer is (Sb x Te1 x )1 y R y , R comprises a non-metal material element, and 0.7

Images