Compound-doped Ge-Sb-Te Phase Change Material and Phase Change Memory Based on Lattice Matching

Abstract

The present invention provides a compound-doped Ge-Sb-Te phase change material and a phase change memory based on lattice matching, belonging to the field of micro-nano electronic technology, and its chemical formula is (MA) x (Ge-Sb-Te) 1‑x , wherein MA is a high-melting-point compound with a face-centered cubic structure, its melting point is greater than 900K, the high-melting-point compound MA with a face-centered cubic structure is lattice-matched with the Ge-Sb-Te system, x represents the percentage of the number of face-centered cubic structure compound molecules in the total number of molecules, 0

Description

Technical Field

[0001] The present invention belongs to the field of micro-nano electronic technology, and more specifically, relates to a compound-doped Ge-Sb-Te phase change material based on lattice matching and a phase change memory. Background Art

[0002] In the current era of rapid development of electronic technology and information industry, with the explosive growth of data, people's requirements for the performance of non-volatile memories are also getting higher and higher. Phase change memory (PCM) is considered by the International Semiconductor Industry Association to be most likely to replace flash memory and dynamic memory and become the future mainstream memory due to its advantages such as high integration, fast response speed, long cycle life, and low power consumption.

[0003] The basic principle of the phase change memory is to apply an electric pulse signal to the storage unit to cause a reversible phase change of the phase change material between the amorphous state and the crystalline state to achieve the storage of "0" and "1". Applying a narrow pulse width and high amplitude electric pulse to the unit for RESET operation, the crystalline phase change storage material melts and rapidly cools to transform into an amorphous disordered state, thus achieving a rapid resistance change from the low resistance state "0" to the high resistance state "1". Conversely, applying a wide pulse width and low amplitude electric pulse to the phase change unit for SET operation, the amorphous phase change storage material undergoes a crystallization process similar to annealing and returns to the low resistance state, realizing the rewrite of "1" back to "0".

[0004] The optimization of the performance of the phase change material is the key to improving the performance of the phase change memory, and the microstructure of the phase change material determines its macroscopic properties. It is found that the reliability and cycle rewrite characteristics of the phase change memory are mainly related to the internal atomic migration mechanism of the phase change material during repeated heating and cooling processes. The data retention time of the phase change memory is mainly determined by the amorphous stability of the phase change material. The rewrite speed of the phase change memory is mainly determined by the crystallization speed of the phase change material.

[0005] The phase change material is mainly a chalcogenide compound material, among which, the compound composed of the three elements Ge, Sb, and Te is the most common. The Ge-Sb-Te system is a phase change material that has received extensive attention in recent years. It combines the advantages of the Sb-Te system and the Ge-Te system. However, the cycle performance of the phase change memory device based on the Ge-Sb-Te system is poor and the phase change speed cannot meet the applications in aspects such as memory-level memories. Therefore, the cycle performance and rewrite speed of the phase change memory device based on the Ge-Sb-Te system need to be further improved.

[0006] At present, the main means of optimizing the performance of Ge-Sb-Te system phase change materials is doping. By introducing other elements into the Ge-Sb-Te system phase change materials to form different microstructures, the local properties of the phase change materials are changed, thereby improving the performance of the phase change memory devices. The existing improvement mechanism of doping in the Ge-Sb-Te system is mainly that the doped single element (such as N, Sc, Al, Ti, etc.) forms bonds with one or several elements in the Ge-Sb-Te system, locally regulates the crystallization process of the Ge-Sb-Te system, and improves the amorphous stability of the Ge-Sb-Te system materials and the performance of the devices. This doping method has a simple process, but the incorporated single element generally combines with a certain element in the substrate phase change material to form a bond, changing the original composition of the phase change material and destroying the lattice structure of the phase change material. While the high-resistance stability of the device is improved, the crystallization speed will be sacrificed to a certain extent, and it is difficult to achieve an overall improvement in the performance of the device.

[0007] Therefore, it is necessary to develop a new method for modifying the Ge-Sb-Te system to achieve precise, sensitive, and simple regulation of its microstructure, so as to comprehensively improve the device performance and enable it to be applied as a commercial phase change memory material. Summary of the Invention

[0008] Aiming at the defects of the prior art, the purpose of the present invention is to provide a compound-doped Ge-Sb-Te phase change material and a phase change memory based on lattice matching. By doping with a stable face-centered cubic structure compound based on lattice matching, the crystallization is accelerated, the lattice structure of the phase change material is ensured to be complete, thereby improving the cycling performance of the device, reducing the grain size, preventing the atomic migration of the phase change elements, improving the stability of the device, and finally comprehensively improving the comprehensive performance of the device.

[0009] To achieve the above purpose, the present invention provides a compound-doped Ge-Sb-Te phase change material based on lattice matching, and its chemical formula is (MA) x (Ge-Sb-Te) 1-x , where MA is a high-melting-point compound with a face-centered cubic structure, whose melting point is higher than that of the Ge-Sb-Te phase change material, the melting point is greater than 900K, the high-melting-point compound MA with a face-centered cubic structure is lattice-matched with the Ge-Sb-Te system, x represents the percentage of the number of face-centered cubic structure compound molecules in the total number of molecules, 0 < x < 10%, and the MA includes one or more of SrS, CaSe, CaS, ScN, ScBi, TiN, and HfN.

[0010] Furthermore, the high-melting-point compound MA with a face-centered cubic structure forms stable nucleation points in the Ge-Sb-Te system phase change layer, and is used as a crystallization template for the Ge-Sb-Te system during the crystallization process, which can accelerate the crystallization of the Ge-Sb-Te system.

[0011] Furthermore, the M element and the A element in the high melting point compound MA with a face-centered cubic structure are independent of the elements in the Ge-Sb-Te system phase change material, without bonding, substitution, or interstitial doping, thus ensuring the integrity of the lattice structure of the phase change material and ultimately improving the cycling performance of the device.

[0012] Furthermore, the high melting point compound MA with a face-centered cubic structure is uniformly distributed in the form of an amorphous at the grain boundaries of the crystalline Ge-Sb-Te system phase change material, which can be used to reduce the grain size of the Ge-Sb-Te system phase change material and hinder the atomic migration of the phase change elements, ultimately improving the reliability of the device.

[0013] Furthermore, the Ge-Sb-Te system phase change material includes one or more of Ge2Sb2Te5, Ge1Sb2Te4, and Ge1Sb4Te7.

[0014] Furthermore, it is prepared by magnetron sputtering, chemical vapor deposition, atomic layer deposition, electroplating, or / and electron beam evaporation.

[0015] Furthermore, it is prepared by co-sputtering of a Ge-Sb-Te system target and an MA target.

[0016] According to the second aspect of the present invention, there is also provided a phase change memory using the phase change material, which includes a bottom electrode, an isolation layer, a phase change memory material thin film layer, and a top electrode stacked in sequence, wherein the phase change memory material thin film layer uses the lattice matching-based compound-doped Ge-Sb-Te phase change material as described above.

[0017] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following beneficial effects are obtained:

[0018] In the phase change material doped with a stable face-centered cubic structure compound based on lattice matching of the present invention, the compound MA forms stable nucleation points in the Ge-Sb-Te system phase change layer, providing a template for the crystallization of the amorphous Ge-Sb-Te system and accelerating the crystallization of the amorphous Ge-Sb-Te system; the chemical bond energy of the compound MA is large and it hardly forms bonds with the elements in the Ge-Sb-Te system material in the thin film material, only forming M-A, M-M, and A-A bonds, without substitution or interstitial doping, ensuring the integrity of the lattice structure of the Ge-Sb-Te system phase change material and improving the cycling performance of the device; in addition, the compound MA is uniformly distributed in the form of an amorphous at the grain boundaries of the Ge-Sb-Te system, effectively reducing the grain size and hindering the atomic migration of the phase change elements, improving the reliability of the device, thereby comprehensively improving the comprehensive performance of the device. Description of the Drawings

[0019] Figure 1It is a schematic diagram of the atomic structure in which the doped cubic structure compound in the present invention stably exists in the Ge-Sb-Te matrix material.

[0020] Figure 2 It is a flowchart for preparing a phase change memory of a Ge-Sb-Te system phase change material doped with a stable face-centered cubic structure compound based on lattice matching provided in Embodiment 2 of the present invention.

[0021] Figure 3 It is an R-V test diagram of two different devices in Example 4 and Comparative Example 1 under a fixed pulse width of 8 ns.

[0022] Figure 4 It is a test diagram of the cycling characteristics of the phase change memory device based on TiN-Ge1Sb4Te7 in Example 4 under a fixed pulse width of 20 ns.

[0023] Figure 5 It is a test diagram of the cycling characteristics of the phase change memory device based on pure Ge1Sb4Te7 in Comparative Example 1 under a fixed pulse width of 20 ns.

[0024] Figure 6 It is a schematic diagram of the structural positions of atoms in the phase change material model of the Ge-Sb-Te system doped with a stable face-centered cubic structure compound based on lattice matching after moving for 60 ps at a temperature of 600 K by using first-principles simulation. Detailed implementation manners

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] This invention application relates to an information storage device, particularly to a novel Ge-Sb-Te system phase change material and phase change memory doped with a stable face-centered cubic structure compound based on lattice matching, which has fast high-cycle performance. It involves a doping process of a stable face-centered cubic structure compound using lattice matching, and uses the compound structure to regulate the Ge-Sb-Te system phase change material. By doping with a stable face-centered cubic structure compound through lattice matching, stable nucleation points are formed in the Ge-Sb-Te system phase change layer. Its face-centered cubic structure that matches the Ge-Sb-Te system lattice provides a reliable crystallization template to accelerate the crystallization of Ge-Sb-Te. The elements in the stable face-centered cubic structure compound hardly bond with the elements in the Ge-Sb-Te system phase change material, so there is no substitution or interstitial doping, ensuring the integrity of the phase change material lattice structure, thereby improving the cycle performance of the device. In addition, the stable face-centered cubic structure compound is easily uniformly distributed in the form of amorphous at the grain boundaries of the crystalline phase change material, reducing the grain size, preventing the atomic migration of phase change elements, and improving the stability of the device, ultimately comprehensively improving the comprehensive performance of the device.

[0027] Figure 1 It is a schematic diagram of the atomic structure in which the doped cubic structure compound in the present invention stably exists in the Ge-Sb-Te matrix material. As can be seen from the figure, the cubic structure compound forms stable nucleation points, and its face-centered cubic structure that matches the Ge-Sb-Te system lattice provides a reliable crystallization template to accelerate the crystallization of Ge-Sb-Te. The phase change material obtained by introducing the stable face-centered cubic structure compound MA that matches the lattice into the Ge-Sb-Te system phase change material in the present invention has a chemical composition general formula of (MA) x (Ge-Sb-Te) 1-x , where MA is a stable face-centered cubic structure compound that matches the lattice, and x represents the percentage of the number of high-melting-point compound molecules in the total number of molecules. The preferred value range of x is 0 < x < 10%, and further preferably x = 5%. By adjusting the sputtering power of MA during preparation, the value of x can be regulated. Preferably, (MA) x (Ge-Sb-Te) 1-x The thickness of the phase change thin film material is 10 nm to 300 nm.

[0028] In an embodiment of the present invention, the phase change memory cell sequentially includes a bottom electrode, an isolation layer, a phase change material thin film layer, and a top electrode. The material of the phase change material thin film layer is the above-mentioned Ge-Sb-Te phase change material doped with a stable face-centered cubic structure compound based on lattice matching, which is filled in a small hole with a diameter of 250 nm and a depth of 100 nm. The material of the bottom electrode is TiN. The material of the isolation layer is SiO2. The material of the top electrode is metal Pt.

[0029] The present invention can also provide a method for preparing a Ge-Sb-Te-based phase change material doped with a lattice-matched stable face-centered cubic structure compound for a phase change memory. The preparation methods include magnetron sputtering, chemical vapor deposition, atomic layer deposition, electroplating, electron beam evaporation, etc. Among them, magnetron sputtering is the most flexible. A Ge-Sb-Te system target and an MA target can be co-sputtered. This method can prepare the Ge-Sb-Te-based phase change material doped with the lattice-matched stable face-centered cubic structure compound of the present invention according to the ratio of the chemical formula.

[0030] The Ge-Sb-Te-based phase change storage material doped with the lattice-matched stable face-centered cubic structure compound of the present invention and the device preparation process are mature, and it is easy to be compatible with the existing microelectronic process technology. By using the doped lattice-matched stable face-centered cubic structure compound tissue to regulate the Ge-Sb-Te-based phase change material, stable nucleation points are formed in the Ge-Sb-Te-based phase change layer. Its face-centered cubic structure lattice-matched with the Ge-Sb-Te system provides a reliable crystallization template to accelerate the crystallization of Ge-Sb-Te. The elements in the stable face-centered cubic structure compound hardly bond with the elements in the Ge-Sb-Te-based phase change material, so substitution or interstitial doping does not occur, ensuring the integrity of the lattice structure of the phase change material, thereby improving the cycling performance of the device. In addition, the stable face-centered cubic structure compound is easily uniformly distributed in the grain boundaries of the crystalline phase change material in an amorphous form, reducing the grain size, preventing the atomic migration of the phase change elements, and improving the stability of the device, thereby improving the comprehensive performance of the Ge-Sb-Te-based phase change memory.

[0031] To elaborate the method and material of the present invention in more detail, the following further details are described with more specific embodiments.

[0032] Example 1

[0033] In this example, the chemical formula of the Ge2Sb2Te5 phase change thin film material doped with the lattice-matched stable face-centered cubic structure compound for the phase change storage device is (MA)x(GST)1-x, where MA represents SrS and GST represents Ge2Sb2Te5. In this example, x = 0.05.

[0034] The SrS-Ge2Sb2Te5 phase change storage thin film material is prepared by magnetron sputtering. High-purity argon is introduced as the sputtering gas during preparation. The sputtering pressure is 0.5 Pa. The Ge2Sb2Te5 target uses a DC power supply with a power of 30 W; the SrS target uses an AC power supply with a power of 60 W. The specific preparation process includes the following steps:

[0035] 1. Select a SiO2 / Si substrate (lattice orientation is 100 direction) with a size of 1 cm × 1 cm, clean the front and back surfaces to remove dust particles, organic and inorganic impurities.

[0036] a) Place the SiO2 / Si (lattice orientation is 100 direction) substrate in acetone solution and ultrasonically vibrate it at a power of 40 W for 10 minutes, then rinse it with deionized water.

[0037] b) Place the substrate treated with acetone in ethanol solution and ultrasonically vibrate it at a power of 40 W for 10 minutes, then rinse it with deionized water and dry the front and back surfaces with high-purity N2 gas to obtain the substrate to be sputtered.

[0038] 2. Prepare the SrS-Ge2Sb2Te5 phase change memory thin film material by using the DC-AC power co-sputtering method.

[0039] a) Place the SrS target and the Ge2Sb2Te5 alloy target, both with a purity of 99.99% (atomic percentage), and pump the background vacuum to 10 -4 Pa.

[0040] b) Use high-purity Ar gas as the sputtering gas, adjust the sputtering pressure to 0.5 Pa, and the distance between the target and the substrate is 120 mm.

[0041] c) Set the DC power to 30 W and the AC power to 60 W.

[0042] d) Pre-sputter the SrS target and the Ge2Sb2Te5 target for 10 min to clean the target surfaces.

[0043] e) After the pre-sputtering is completed, open the baffle. When the sputtering time is 6 min, the thickness of the prepared thin film is about 100 nm.

[0044] Example 2

[0045] In this example, a phase change thin film material of SrS-doped Ge2Sb2Te5 is used as the phase change layer material to prepare a storage device, and the SrS-doped Ge2Sb2Te5 phase change layer is obtained by magnetron sputtering. When preparing, high-purity argon gas is introduced as the sputtering gas, the sputtering pressure is 0.5 Pa, the Ge2Sb2Te5 target uses a DC power supply with a power of 30 W; the SrS target uses an AC power supply with a power of 60 W. Figure 2 It is the flowchart of the preparation of a phase change memory based on a lattice-matched stable face-centered cubic structure compound-doped Ge-Sb-Te system phase change material provided by Example 2 of the present invention. As can be seen from the figure, the specific preparation process includes the following steps:

[0046] 1. Select a SiO2 / Si(100) substrate with a size of 1 cm × 1 cm, clean the front and back surfaces to remove dust particles, organic and inorganic impurities.

[0047] a) Place the SiO2 / Si(100) substrate in an acetone solution and ultrasonically vibrate it at a power of 40 W for 10 minutes, then rinse with deionized water.

[0048] b) Place the substrate treated with acetone in an ethanol solution and ultrasonically vibrate it at a power of 40 W for 10 minutes, then rinse with deionized water and dry the front and back surfaces with high-purity N2 gas to obtain the substrate to be sputtered.

[0049] 2. Prepare a 100-nm TiN bottom electrode by DC magnetron sputtering.

[0050] 3. Deposit a 100-nm SiO2 insulating layer on the TiN bottom electrode by chemical vapor deposition.

[0051] 4. Form vias with a depth of 100 nm and a diameter of 250 nm in the SiO2 insulating layer through processes such as electron beam lithography and etching.

[0052] 5. Form a storage array through photolithography.

[0053] 6. Fill the vias with SrS-Ge2Sb2Te5 phase change memory thin film material by AC magnetron sputtering

[0054] a) Place the SrS target and the Ge2Sb2Te5 alloy target, both with a purity of 99.99% (atomic percentage), and evacuate the background vacuum to 10 -4 Pa.

[0055] b) Use high-purity Ar gas as the sputtering gas, adjust the sputtering pressure to 0.5 Pa, and set the distance between the target and the substrate to 120 mm.

[0056] c) Set the DC power supply power to 30 W and the AC power supply power to 60 W.

[0057] d) Perform pre-sputtering on the SrS target and the Ge2Sb2Te5 target for 10 minutes to clean the target surface.

[0058] e) After the pre-sputtering is completed, open the baffle. When the sputtering time is 6 minutes, the thickness of the prepared phase change layer is about 100 nm.

[0059] 7. Prepare a 100-nm Pt top electrode by DC magnetron sputtering to obtain a complete phase change memory device array based on the SrS-Ge2Sb2Te5 phase change layer.

[0060] Example 3

[0061] In this embodiment, the chemical general formula of the lattice-matched stable face-centered cubic structure compound-doped Ge1Sb4Te7 phase change thin film material for phase change memory devices is (MA) x (GST) 1-x , where MA represents TiN, GST represents Ge1Sb4Te7, and in this embodiment, x = 0.05.

[0062] The TiN-Ge1Sb4Te7 phase change memory thin film material is prepared by magnetron sputtering. High-purity argon gas is introduced as the sputtering gas during preparation, the sputtering pressure is 0.5 Pa, the Ge1Sb4Te7 target uses a DC power supply with a power of 30 W, and the TiN target uses a DC power supply with a power of 20 W. The specific preparation process includes the following steps:

[0063] 1. Select a SiO2 / Si(100) substrate with a size of 1 cm × 1 cm, clean the front and back surfaces to remove dust particles, organic and inorganic impurities.

[0064] a) Place the SiO2 / Si(100) substrate in an acetone solution and ultrasonically vibrate it at a power of 40 W for 10 minutes, then rinse it with deionized water.

[0065] b) Place the substrate treated with acetone in an ethanol solution and ultrasonically vibrate it at a power of 40 W for 10 minutes, then rinse it with deionized water and dry the front and back surfaces with high-purity N2 gas to obtain the substrate to be sputtered.

[0066] 2. Prepare the TiN-Ge1Sb4Te7 phase change memory thin film material by DC and AC power co-sputtering.

[0067] a) Place the TiN target and the Ge1Sb4Te7 alloy target, both with a purity of 99.99% (atomic percentage), and pump the background vacuum to 10 -4 Pa.

[0068] b) Use high-purity Ar gas as the sputtering gas, adjust the sputtering pressure to 0.5 Pa, and the distance between the target and the substrate is 120 mm.

[0069] c) Set the DC power of the Ge1Sb4Te7 target to 30 W and the DC power of the TiN target to 20 W.

[0070] d) Perform pre-sputtering on the TiN target and the Ge1Sb4Te7 target for 10 minutes to clean the target surface.

[0071] e) After the pre-sputtering is completed, open the baffle. When the sputtering time is 6 minutes, the thickness of the prepared thin film is about 100 nm.

[0072] Example 4

[0073] In this embodiment, a TiN-doped Ge1Sb4Te7 phase change thin film material is used as the phase change layer material to prepare a storage device, and the TiN-doped Ge1Sb4Te7 phase change layer is prepared by magnetron sputtering. High-purity argon gas is introduced as the sputtering gas during preparation, the sputtering pressure is 0.5 Pa, the Ge1Sb4Te7 target uses a DC power supply with a power of 30 W; the TiN target uses a DC power supply with a power of 20 W. The specific preparation process includes the following steps:

[0074] 1. Select a SiO2 / Si(100) substrate with a size of 1 cm × 1 cm, clean the front and back surfaces to remove dust particles, organic and inorganic impurities.

[0075] a) Place the SiO2 / Si(100) substrate in an acetone solution and ultrasonically vibrate it at a power of 40 W for 10 minutes, then rinse it with deionized water.

[0076] b) Place the substrate treated with acetone in an ethanol solution and ultrasonically vibrate it at a power of 40 W for 10 minutes, then rinse it with deionized water and dry the front and back surfaces with high-purity N2 gas to obtain the substrate to be sputtered.

[0077] 2. Prepare a 100-nm TiN bottom electrode by DC power sputtering.

[0078] 3. Deposit a 100-nm SiO2 insulating layer on the TiN bottom electrode by chemical vapor deposition.

[0079] 4. Form a through hole with a depth of 100 nm and a diameter of 250 nm in the SiO2 insulating layer through processes such as electron beam lithography and etching.

[0080] 5. Form a storage array through lithography.

[0081] 6. Fill the through hole with a TiN-Ge1Sb4Te7 phase change storage thin film material by AC power sputtering

[0082] a) Place the TiN target and the Ge1Sb4Te7 alloy target, both with a purity of 99.99% (atomic percentage), and pump the background vacuum to 10 -4 Pa.

[0083] b) Use high-purity Ar gas as the sputtering gas, adjust the sputtering pressure to 0.5 Pa, and the distance between the target and the substrate is 120 mm.

[0084] c) Set the DC power of the Ge1Sb4Te7 target to 30 W and the DC power of the TiN target to 20 W.

[0085] d) Perform pre-sputtering on the TiN target and the Ge1Sb4Te7 target for 10 minutes to clean the target surface.

[0086] e) After the pre-sputtering is completed, open the baffle. When the sputtering time is 6 min, the thickness of the phase change layer prepared is about 100 nm.

[0087] 7. Use the DC power sputtering method to prepare a 100-nm Pt top electrode, and obtain a complete phase change memory device array based on the TiN-Ge1Sb4Te7 phase change layer.

[0088] Comparative Example 1

[0089] In this comparative example, a pure Ge1Sb4Te7 phase change thin film material is used as the phase change layer material to prepare a memory device. Among them, the pure Ge1Sb4Te7 phase change layer is prepared by magnetron sputtering. High-purity argon gas is introduced as the sputtering gas during the preparation, the sputtering pressure is 0.5 Pa, the Ge1Sb4Te7 target uses a DC power supply, and the power of the power supply is 30 W. The specific preparation process includes the following steps:

[0090] 1. Select a SiO2 / Si(100) substrate with a size of 1 cm × 1 cm, clean the front and back surfaces, and remove dust particles, organic and inorganic impurities.

[0091] a) Place the SiO2 / Si(100) substrate in an acetone solution and ultrasonically vibrate it at a power of 40 W for 10 minutes, then rinse it with deionized water.

[0092] b) Place the substrate treated with acetone in an ethanol solution and ultrasonically vibrate it at a power of 40 W for 10 minutes, then rinse it with deionized water and dry the front and back surfaces with high-purity N2 gas to obtain the substrate to be sputtered.

[0093] 2. Use the DC power sputtering method to prepare a 100-nm TiN bottom electrode.

[0094] 3. Deposit a 100-nm SiO2 insulating layer on the TiN bottom electrode by chemical vapor deposition.

[0095] 4. Form a through hole with a depth of 100 nm and a diameter of 250 nm in the SiO2 insulating layer through processes such as electron beam lithography and etching.

[0096] 5. Form a memory array through the lithography process.

[0097] 6. Use the AC power sputtering method to fill the through hole with the Ge1Sb4Te7 phase change memory thin film material.

[0098] a) Place the Ge1Sb4Te7 alloy target, and its purity reaches 99.99% (atomic percentage). Pump its background vacuum to 10 -4 Pa.

[0099] b) Using high-purity Ar gas as the sputtering gas, adjust the sputtering pressure to 0.5 Pa, and the distance between the target and the substrate is 120 mm.

[0100] c) Set the DC power of the Ge1Sb4Te7 target to 30 W.

[0101] d) Perform pre-sputtering on the Ge1Sb4Te7 target for 10 min to clean the surface of the target.

[0102] e) After the pre-sputtering is completed, open the baffle. When the sputtering time is 6 min, the thickness of the prepared phase change layer is about 100 nm.

[0103] 7. Use DC magnetron sputtering to deposit a 100-nm Pt top electrode to obtain a complete phase change memory device array based on the Ge1Sb4Te7 phase change layer.

[0104] Perform electrical property tests on the TiN-Ge1Sb4Te7 phase change memory devices and pure Ge1Sb4Te7 phase change memory devices in Example 4 and Comparative Example 1 above, respectively.

[0105] Figure 3 is the R-V test diagram of two different devices in Example 4 and Comparative Example 1 under a fixed pulse width of 8 ns, which reflects the SET speed performance of the devices. It can be seen from the figure that, obviously, the phase change memory based on TiN-Ge1Sb4Te7 can successfully SET from the high-resistance state to the low-resistance state under an 8-ns pulse width; while the pulse amplitude of the phase change memory device based on pure Ge1Sb4Te7 increases to 2.4 V and still cannot successfully SET the device. This shows that the operation speed of the TiN-Ge1Sb4Te7 phase change memory device doped with lattice-matched compounds has been greatly improved.

[0106] Figure 4 and Figure 5 is the cycling characteristics test diagram of two different devices in Example 4 and Comparative Example 1 under a fixed pulse width of 20 ns. Figure 4 In, the maximum number of cycles of the phase change memory device based on TiN-Ge1Sb4Te7 is close to E9 times, while Figure 5 In, the maximum number of cycles of the phase change memory device based on pure Ge1Sb4Te7 is 3.5E6 times. It is verified that doping with a stable face-centered cubic structure compound can improve the cycling performance of Ge-Sb-Te-based phase change memory devices.

[0107] Use Materials Studio software to model the TiN-Ge1Sb4Te7 phase change memory thin film material doped with lattice-matched compounds, and use the first-principles method to simulate the movement of atoms in the model at a temperature of 600 K. Figure 6It is a schematic diagram of the structural positions of atoms in a phase change material model of a Ge-Sb-Te system doped with a stable face-centered cubic structure compound based on lattice matching after 60 ps of movement at a temperature of 600K simulated by first principles. It can be found that the doped TiN still exists stably in a combined state in the Ge1Sb4Te7 system, providing stable nucleation points with structural matching for the system.

[0108] In the above embodiments, the high melting point compounds MA with a face-centered cubic structure selected SrS and TiN, and the phase change materials of the Ge-Sb-Te system selected Ge2Sb2Te5 and Ge1Sb4Te7. In fact, the phase change materials of the Ge-Sb-Te system can also select Ge1Sb2Te4, and the high melting point compounds MA with a face-centered cubic structure can also select one or more of CaSe, CaS, ScN, ScBi, and HfN. For example, CaSe-Ge1Sb2Te4, CaS-Ge2Sb2Te5, ScN-Ge1Sb4Te7, ScBi-Ge2Sb2Te5, and HfN-Ge2Sb2Te5, etc.

[0109] Compared with the Ge-Sb-Te system phase change storage materials in the prior art that are not regulated by the organization of stable face-centered cubic structure compounds with lattice matching, in the Ge-Sb-Te system phase change materials doped with stable face-centered cubic structure compounds with lattice matching of the present invention, the organization of the doped stable face-centered cubic structure compounds with lattice matching is used to regulate the Ge-Sb-Te system phase change materials, forming stable nucleation points in the Ge-Sb-Te system phase change layer. Its face-centered cubic structure with lattice matching with the Ge-Sb-Te system provides a reliable crystallization template to accelerate crystallization; the elements in the stable face-centered cubic structure compound hardly bond with the elements in the Ge-Sb-Te system phase change materials, so there is no substitution or interstitial doping, ensuring the integrity of the lattice structure of the phase change materials, thereby improving the cycling performance of the device; in addition, the stable face-centered cubic structure compound is easily uniformly distributed in the form of amorphous at the grain boundaries of the crystalline phase change materials, reducing the grain size, preventing the atomic migration of the phase change elements, and improving the stability of the device, ultimately comprehensively improving the comprehensive performance of the device.

[0110] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A compound-doped Ge-Sb-Te phase change material based on lattice matching, characterized in that Its chemical formula is (MA) x (Ge-Sb-Te) 1-x , where MA is a high-melting-point compound with a face-centered cubic structure. The high-melting-point compound MA with a face-centered cubic structure is uniformly distributed in the grain boundaries of the crystalline Ge-Sb-Te system phase change material in an amorphous form. Its melting point is higher than 900K. The high-melting-point compound MA with a face-centered cubic structure is lattice-matched with the Ge-Sb-Te system. x represents the percentage of the number of face-centered cubic structure compound molecules in the total number of molecules, 0 < x < 10%. The MA includes one or more of SrS, CaSe, CaS, ScN, and ScBi. The M element and A element in the high-melting-point compound MA with a face-centered cubic structure are independent of the elements in the Ge-Sb-Te system phase change material, without bonding, substitution, and interstitial doping, so as to ensure the integrity of the lattice structure during the crystallization of the phase change material and ultimately improve the cycling performance of the device.

2. The Ge-Sb-Te phase change material doped with a compound based on lattice matching according to claim 1, wherein High melting point compound MA with a face-centered cubic structure is doped in the phase change layer of the Ge-Sb-Te system to form stable nucleation sites, which are used as crystallization templates for the Ge-Sb-Te system during the crystallization process and can accelerate the crystallization of the Ge-Sb-Te system.

3. The Ge-Sb-Te phase change material doped with a compound based on lattice matching according to claim 2, wherein The Ge-Sb-Te system phase change material is selected from one or more of Ge2Sb2Te5, Ge1Sb2Te4, and Ge1Sb4Te7.

4. The Ge-Sb-Te phase change material doped with a compound based on lattice matching according to claim 3, characterized in that It is prepared by magnetron sputtering, chemical vapor deposition, atomic layer deposition, electroplating, or / and electron beam evaporation.

5. The Ge-Sb-Te phase change material doped with a compound based on lattice matching according to claim 4, wherein It is prepared by co-sputtering a Ge-Sb-Te system target and an MA target.

6. A phase change memory of a phase change material, characterized in that, It includes a bottom electrode, an isolation layer, a phase change storage material thin film layer, and a top electrode stacked in sequence. Among them, the phase change storage material thin film layer uses the lattice-matching compound-doped Ge-Sb-Te phase change material described in one of claims 1-5.

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