Nanocomposite stacked phase change film, and preparation method and application thereof

Abstract

The application relates to a nanocomposite stacked phase change film and a preparation method and application thereof, the nanocomposite stacked phase change film is prepared from Ta5Sb 95 The thin film and a GeSb6Te thin film are alternately arranged into a stacked film unit, the stacked film unit is one layer, and the structure conforms to the following general formula: [Ta5Sb 95 (a) / GeSb6Te(b)]1, wherein 10<=a<=20nm, 20<=b<=40nm. Compared with the prior art, the nanocomposite stacked film prepared by the method of room-temperature magnetron sputtering has a simpler structure than the current nanocomposite multilayer film, is beneficial to simplifying the film preparation process, has twice stable phase change processes, can realize multi-level storage and thus improve storage density, and has the advantages of Ta5Sb 95 and GeSb6Te, the phase change performance can be controlled by controlling structure parameters, and the application has sufficient potential in the application aspect of phase change memories.

Description

Technical Field

[0001] This invention relates to the field of microelectronic materials technology, and in particular to a nanocomposite stacked phase change thin film, its preparation method and application. Background Technology

[0002] Phase-change memory (PCM), as a novel storage technology, has a long history, dating back to 1968 when American scientist Stanford R. Ovshinsky discovered a unique phenomenon: chalcogenides could undergo a reversible "order-disorder" transition. However, due to the limitations of semiconductor technology at the time, achieving the reversible transition of phase-change units required very high drive currents, hindering commercialization. The phase-change process results in a significant difference in reflectivity between crystalline and amorphous states. Initially, phase-change materials were used in optical storage, such as rewritable CD-RW, rewritable DVD-RW, DVD-RAM, and Blu-ray phase-change discs. It wasn't until the rapid advancements in semiconductor technology in the 21st century that PCM truly entered the public eye.

[0003] Phase change memory (PCM) is a novel semiconductor data storage technology that uses the resistance difference between a crystalline (low-resistance) and amorphous (high-resistance) phase change materials to write and erase "0" and "1" information, and outputs information by varying the resistance levels. Applying a medium-intensity, long-pulse current to a PCM memory cell causes the temperature of the amorphous material region to rise. When the temperature exceeds the crystallization temperature (Tc) but falls below the melting point (Tm), and this continues for a certain period, a phase transition from amorphous to crystalline occurs, changing the material from a high-resistance state to a low-resistance state—this is the SET process. Applying a higher-intensity, shorter-duration current pulse to the crystalline region of the phase change material causes the temperature to rise rapidly, exceeding its melting point. Following a rapid cooling and quenching process, the material transitions from a molten, disordered state to an amorphous state. The long-range order of polycrystalline materials is disrupted; this process is the RESET process.

[0004] Phase change materials (PCMs) serve as information storage carriers, and their properties directly determine the performance of PCM devices. Currently, Ge2Sb2Te5 is widely recognized as the most widely used, best-performing, and most competitive PCM material. However, it still has many areas for improvement, such as relatively slow crystallization rate, poor thermal stability, and significant volume changes before and after phase change. Therefore, researchers have improved its performance by doping with various elements or through multilayer composites. Cheng L et al., by doping nitrogen into Ge2Sb2Te5 thin films, found that the resulting germanium nitride increased the optical band gap and suppressed grain growth, leading to an increase in the crystallization temperature and resistivity of the FCC phase, thus improving the thermal stability and reducing power consumption of the PCM. Chinese patent CN111463345A discloses a Ta-Ge-Sb-Te phase change material, its preparation method, and a phase change memory unit. By adjusting the content of tantalum (Ta), germanium (Ge), antimony (Sb), and tellurium (Te) elements in the material, as well as the thickness of the thin film, phase change materials with different crystallization temperatures, resistivity, and crystallization activation energies can be obtained. However, in practical applications, it is difficult to precisely control the content of each element, placing excessively high demands on the process. Chinese patent CN111276605A discloses a high-speed superlattice-like zinc-antimony phase change memory medium and its preparation method, using Zn... 50 Sb 50 Multilayer nanocomposite with Sb and two phase change materials comprehensively utilizes the advantages of the two phase change materials, greatly improving the thermal stability and phase change rate of PCM. However, the two resistive states limit its storage density. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a nanocomposite stacked phase change thin film, its preparation method, and its application. This involves using magnetron sputtering to prepare Ta5Sb with a relatively fast phase change rate. 95 By combining phase change materials with thermally stable GeSb6Te phase change materials, a Ta5Sb material that not only possesses high thermal stability but also enables multi-level storage is provided. 95 / GeSb6Te nanocomposite stacked phase change films not only have a faster phase change rate and higher thermal stability, but also enable multi-level storage. Moreover, the process is simpler than that of nanomultilayer composite films, and the application cost is lower.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] The first objective of this invention is to provide a nanocomposite stacked phase change film, which is composed of Ta5Sb 95 Alternating thin films and GeSb6Te thin films are arranged in a stacked thin film unit, which is a single layer, and its structure conforms to the following general formula: [Ta5Sb95 [a) / GeSb6Te(b)]1, which can be abbreviated as [TS(a) / GS6T(b)]. Where a and b represent Ta5Sb... 95 The thicknesses of the thin film and the GeSb6Te thin film are such that 10 ≤ a ≤ 20 nm and 20 ≤ b ≤ 40 nm.

[0008] Preferably, the Ta5Sb 95 The thicknesses of the thin film and the GeSb6Te thin film are 10 nm and 40 nm, respectively.

[0009] A second objective of this invention is to provide a method for preparing nanocomposite stacked phase change thin films, the method comprising the following steps:

[0010] (1) Clean the substrate;

[0011] (2) Install Ta5Sb 95 For the target material and GeSb6Te target material, the mechanical pump and molecular pump were turned on in sequence to evacuate the vacuum. High-purity argon was used as the sputtering gas, and the radio frequency power, gas flow rate, sputtering pressure and substrate rotation speed were set.

[0012] (3) The target material was sputtered by room temperature magnetron sputtering to prepare nanocomposite stacked phase change thin films.

[0013] Furthermore, step (1) includes the following sub-steps:

[0014] (1a) Place the substrate in an ethanol solution and clean it with ultrasound for 20 minutes to remove dust particles and inorganic impurities from the surface of the substrate.

[0015] (1b) Place the substrate in an acetone solution and clean it with ultrasonication for 10 minutes to remove organic impurities from the surface of the substrate.

[0016] (1c) Place the substrate in deionized water and clean it with ultrasonication for 10 minutes, then clean the surface again.

[0017] (1d) Remove the substrate, dry the surface and back side with high-purity N2, and place it in a drying oven for later use.

[0018] Preferably, the purity of the high-purity N2 in step (1d) is 99.999% or higher by volume.

[0019] Furthermore, step (3) includes the following sub-steps:

[0020] (3a) Rotate the substrate to Ta5Sb 95 At the target site, turn on the RF sputtering power supply and sputter Ta5Sb. 95 Target material, Ta5Sb 95 After the thin film sputtering is complete, turn off Ta5Sb.95 RF sputtering power supply for the target site;

[0021] (3b) Rotate the substrate to the GeSb6Te target position, turn on the RF sputtering power supply, sputter the GeSb6Te target material, and turn off the RF sputtering power supply of the GeSb6Te target position after the GeSb6Te thin film sputtering is completed.

[0022] Preferably, the substrate is a SiO2 / Si(100) substrate.

[0023] Preferably, the Ta5Sb 95 The purity of both the target material and the GeSb6Te target material is above 99.999% atomically.

[0024] Preferably, the vacuum level after vacuuming in step (2) is less than 2.5 × 10⁻⁶. -4 Pa.

[0025] Preferably, the purity of the high-purity argon gas in step (2) is 99.999% or higher by volume.

[0026] Preferably, the sputtering pressure in step (2) is 0.3 Pa.

[0027] Preferably, the gas flow rate in step (2) is 30 SCCM.

[0028] Preferably, the base rotation speed in step (2) is 20 r / min, which is controlled by a program.

[0029] Preferably, the target sputtering in step (3) is carried out by radio frequency sputtering with a sputtering power of 20W.

[0030] The nanocomposite stacked phase change thin films prepared by the above method have good thermal stability, small volume before and after phase change, and the ability to achieve multi-level phase change, and can be used as phase change medium layers in phase change memory.

[0031] The third objective of this invention is to provide an application of a nanocomposite stacked phase change film, characterized in that the nanocomposite stacked phase change film is used in the field of phase change memory.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1) Compared with traditional GST phase change materials, the nanocomposite stacked phase change film provided by this invention has a higher phase change temperature, indicating that it has higher thermal stability and can be used for information storage in high-temperature environments.

[0034] 2) The nanocomposite stacked phase change film provided by the present invention has three resistance states: high, medium and low, and can realize multi-level storage, which can greatly improve the storage density of the phase change memory. Moreover, the stability of the intermediate resistance state is better, and the data is not easily lost during the data storage process.

[0035] 3) The nanocomposite stacked phase change film provided by this invention uses an Sb-rich material system, which gives the film the advantage of a faster phase change rate.

[0036] 4) Compared with current nanocomposite multilayer films, the preparation steps of the nanocomposite stacked phase change film provided by the present invention are simpler and easier to operate, making it more suitable for practical application production.

[0037] 5) The volume change rate of the nanocomposite stacked phase change film provided by the present invention before and after crystallization is less than that of the Ge2Sb2Te5 phase change film, indicating that it is less likely to fail due to excessive volume change during application and has greater reliability. Attached Figure Description

[0038] Figure 1 [Ta5Sb] prepared in Example 1 95 [10nm] / GeSb6Te(20nm)]1 nanometer composite stacked phase change film, [Ta5Sb 95 [10nm] / GeSb6Te(40nm)]1 nanometer composite stacked phase change film, [Ta5Sb 95 [(20nm) / GeSb6Te(40nm)]1 nanocomposite stacked phase change film, Comparative Example 1: monolayer Ta5Sb 95 The resistance versus temperature curves of the (50nm) thin film and the GeSb6Te (50nm) thin film prepared in Comparative Example 2;

[0039] Figure 2 [Ta5Sb] prepared in Example 1 95 The curve showing the relationship between the failure time and the reciprocal of temperature for a 10nm / GeSb6Te(40nm)]1 nanometer composite stacked phase change film.

[0040] Figure 3 [Ta5Sb] prepared in Example 1 95 XRD curves of [10nm] / GeSb6Te(40nm)]1 nanometer composite stacked phase change thin film at different temperatures;

[0041] Figure 4 [Ta5Sb] prepared in Example 1 95 The curve showing the relationship between the X-ray reflectance of the (10nm) / GeSb6Te(40nm)]1 nanometer composite stacked phase change film and the incident angle;

[0042] Figure 5 [Ta5Sb] prepared based on Example 1 95 IV characteristic curves of phase change memory device units of [10nm] / GeSb6Te(40nm)]1 nanometer composite stacked phase change thin films.

[0043] Figure 6 [Ta5Sb] prepared based on Example 1 95 RV characteristic curves of phase change memory device units of [10nm] / GeSb6Te(40nm)]1 nanometer composite stacked phase change thin films. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0045] Any preparation methods, materials, structures, or composition ratios not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0046] This invention selects Ta5Sb with a fast phase transition rate. 95 Alternating composites with thermally stable GeSb6Te materials to form thin films not only have a faster phase transition rate and higher thermal stability, but also enable multi-level storage. Moreover, the process is simpler than that of nano-multilayer composite films, and the application cost is relatively lower.

[0047] Example 1

[0048] The nanocomposite stacked thin film prepared in this embodiment has the general structural formula [Ta5Sb]. 95 (a) / GeSb6Te(b)]1, the specific structures are [Ta5Sb 95 (10nm) / GeSb6Te(20nm)]1, [Ta5Sb 95 (10nm) / GeSb6Te(40nm)]1, [Ta5Sb 95 [(20nm) / GeSb6Te(40nm)]1.

[0049] The preparation method of the above-mentioned nanocomposite stacked phase change thin film includes the following steps:

[0050] (1) Clean the surface and back of the SiO2 / Si(100) substrate to remove dust particles, organic and inorganic impurities:

[0051] (1a) Place the SiO2 / Si(100) substrate in an ethanol solution and clean it with ultrasound for 20 minutes to remove dust particles and inorganic impurities from the surface of the SiO2 / Si(100) substrate.

[0052] (1b) Place the SiO2 / Si(100) substrate in an acetone solution and clean it with ultrasound for 10 minutes to remove organic impurities from the surface of the SiO2 / Si(100) substrate.

[0053] (1c) Place the SiO2 / Si(100) substrate in deionized water and clean it with ultrasonication for 10 minutes, then clean the surface again.

[0054] (1d) Remove the SiO2 / Si(100) substrate, dry the surface and back side with high-purity N2 (purity of 99.999% by volume), and place it in a drying oven for later use.

[0055] (2) [Ta5Sb] was prepared by magnetron sputtering. 95 Preliminary preparation of (a) / GeSb6Te(b)]1 nanocomposite stacked phase change thin films:

[0056] (2a) Ta5Sb 95 The target material and the GeSb6Te target material were placed on target positions 1 and 2 of the sputtering instrument, respectively. The SiO2 / Si(100) substrate was fixed on the sample tray, the external vent valve was closed, and the cavity was sealed.

[0057] (2b) Turn on the vacuum gauge and mechanical pump to evacuate the chamber. When the vacuum inside the chamber reaches 8 Pa or below, start the molecular pump to evacuate to 2.5 × 10⁻⁶ Pa. -4 Below Pa;

[0058] (2c) Set Ta5Sb 95 The RF sputtering power of both the GeSb6Te target and the target is 20W.

[0059] (2d) High-purity Ar gas (purity of 99.999% by volume) was used as the sputtering gas, with the Ar gas flow rate set to 30 SCCM and the sputtering pressure to 0.3 Pa.

[0060] (3) Coating is performed using a coating monitoring program, in which Ta5Sb 95 The sputtering velocity of the target is 0.25 nm / s, and the sputtering velocity of the GeSb6Te target is 0.27 nm / s. The required sputtering thickness can be achieved by controlling the sputtering time.

[0061] (3a) Rotate the substrate to Ta5Sb 95 Target position (target 1), turn on the RF sputtering power supply and sputter Ta5Sb. 95The target material is sputtered for a set time according to the set thickness to obtain Ta5Sb of the corresponding thickness. 95 Thin film, [Ta5Sb 95 (10nm) / GeSb6Te(20nm)]1, [Ta5Sb 95 (10nm) / GeSb6Te(40nm)]1, [Ta5Sb 95 The durations of [(20nm) / GeSb6Te(40nm)]1 were 42s, 45s, and 93s, respectively, corresponding to Ta5Sb 95 The thin films are 10nm, 10nm and 20nm respectively. After sputtering is completed, the RF sputtering power supply of target position 1 is turned off.

[0062] (3b) Rotate the substrate to the GeSb6Te target position (target position 2), turn on the RF sputtering power supply, sputter the GeSb6Te target material, and sputter for the corresponding time according to the set thickness to obtain a GeSb6Te thin film layer of the corresponding thickness, [Ta5Sb 95 (10nm) / GeSb6Te(20nm)]1, [Ta5Sb 95 (10nm) / GeSb6Te(40nm)]1, [Ta5Sb 95 The durations of [(20nm) / GeSb6Te(40nm)]1 were 78s, 154s, and 150s, respectively, corresponding to GeSb6Te films of 20nm, 40nm, and 40nm. After sputtering was completed, the RF sputtering power supply for target position 2 was turned off.

[0063] Comparative Example 1

[0064] The monolayer Ta5Sb prepared in this comparative example 95 The total thickness of the phase change film is 50 nm.

[0065] The above-mentioned single-layer Ta5Sb 95 The preparation method of phase change thin films includes the following steps:

[0066] (1) Clean the surface and back of the SiO2 / Si(100) substrate to remove dust particles, organic and inorganic impurities:

[0067] (1a) Place the SiO2 / Si(100) substrate in an ethanol solution and clean it with ultrasound for 20 minutes to remove dust particles and inorganic impurities from the surface of the SiO2 / Si(100) substrate.

[0068] (1b) Place the SiO2 / Si(100) substrate in an acetone solution and clean it with ultrasound for 10 minutes to remove organic impurities from the surface of the SiO2 / Si(100) substrate.

[0069] (1c) Place the SiO2 / Si(100) substrate in deionized water and clean it with ultrasonication for 10 minutes, then clean the surface again.

[0070] (1d) Remove the SiO2 / Si(100) substrate, dry the surface and back side with high-purity N2 (purity of 99.999% by volume), and place it in a drying oven for later use.

[0071] (2) Preparation of Ta5Sb by magnetron sputtering 95 Preliminary preparations for thin films:

[0072] (2a) Ta5Sb 95 Place the target material on sputtering device No. 1, fix the SiO2 / Si(100) substrate on the sample tray, close the external vent valve, and seal the cavity;

[0073] (2b) Turn on the vacuum gauge and mechanical pump to evacuate the chamber. When the vacuum inside the chamber reaches 8 Pa or below, start the molecular pump to evacuate to 2.5 × 10⁻⁶ Pa. -4 Below Pa;

[0074] (2c) Set Ta5Sb 95 The RF sputtering power of the target materials is 20W;

[0075] (2d) High-purity Ar gas (purity of 99.999% by volume) was used as the sputtering gas, with the Ar gas flow rate set to 30 SCCM and the sputtering pressure to 0.3 Pa.

[0076] (3) Coating was performed using a coating monitoring program, Ta5Sb 95 The sputtering velocity of the target is 0.25 nm / s, and the required sputtering thickness can be achieved by controlling the sputtering time.

[0077] Rotate the substrate to Ta5Sb 95 Target position (target 1), turn on the RF sputtering power supply and sputter Ta5Sb. 95 The target material was sputtered for a set thickness for a corresponding time, with a duration of 210 s, resulting in a 50 nm thick monolayer of Ta5Sb. 95 After the thin film is sputtered, turn off the RF sputtering power supply for target position 1.

[0078] Comparative Example 2

[0079] The total thickness of the monolayer GeSb6Te phase change film prepared in this comparative example is 50 nm.

[0080] The preparation method of the above-mentioned monolayer GeSb6Te phase change thin film includes the following steps:

[0081] (1) Clean the surface and back of the SiO2 / Si(100) substrate to remove dust particles, organic and inorganic impurities:

[0082] (1a) Place the SiO2 / Si(100) substrate in an ethanol solution and clean it with ultrasound for 20 minutes to remove dust particles and inorganic impurities from the surface of the SiO2 / Si(100) substrate.

[0083] (1b) Place the SiO2 / Si(100) substrate in an acetone solution and clean it with ultrasound for 10 minutes to remove organic impurities from the surface of the SiO2 / Si(100) substrate.

[0084] (1c) Place the SiO2 / Si(100) substrate in deionized water and clean it with ultrasonication for 10 minutes, then clean the surface again.

[0085] (1d) Remove the SiO2 / Si(100) substrate, dry the surface and back side with high-purity N2 (purity of 99.999% by volume), and place it in a drying oven for later use.

[0086] (2) Preparatory work for preparing GeSb6Te thin films by magnetron sputtering:

[0087] (2a) Place the GeSb6Te target on sputtering machine No. 1, fix the SiO2 / Si(100) substrate on the sample tray, close the external vent valve, and seal the cavity;

[0088] (2b) Turn on the vacuum gauge and mechanical pump to evacuate the chamber. When the vacuum inside the chamber reaches 8 Pa or below, start the molecular pump to evacuate to 2.5 × 10⁻⁶ Pa. -4 Below Pa;

[0089] (2c) Set the RF sputtering power of GeSb6Te target to 20W;

[0090] (2d) High-purity Ar gas (purity of 99.999% by volume) was used as the sputtering gas, with the Ar gas flow rate set to 30 SCCM and the sputtering pressure to 0.3 Pa.

[0091] (3) The coating was performed using a coating monitoring program. The sputtering rate of the GeSb6Te target was 0.27 nm / s. The required sputtering thickness could be achieved by controlling the sputtering time.

[0092] Rotate the substrate to the GeSb6Te target position (target position 2), turn on the RF sputtering power supply, sputter the GeSb6Te target material, sputter for the set thickness for the corresponding time, the duration is 187s, and a single-layer GeSb6Te film with a thickness of 50nm is obtained by sputtering. After sputtering is completed, turn off the RF sputtering power supply of target position 2.

[0093] The [Ta5Sb] of Example 1 above 95 The resistance versus temperature curves of the (a) / GeSb6Te(b)]1 nano-composite stacked phase change thin films and Comparative Examples 1 and 2 were tested, as shown in Figure 1. Figure 1 As shown; [Ta5Sb] in the above embodiment 1 95 The [10nm] / GeSb6Te(40nm)]1 nanometer composite stacked phase change film was tested. The crystallization activation energy of the nanocomposite stacked phase change film was obtained using the Arrhenius equation, and the ten-year data retention force was calculated. Figure 2 As shown; [Ta5Sb] in Example 1 above 95 The XRD curves of the 10nm / GeSb6Te(40nm)]1 nm composite stacked phase change film were obtained by testing at different temperatures. Figure 3 As shown; [Ta5Sb] in Example 1 above 95 X-ray reflectivity tests were performed on a 10nm / GeSb6Te(40nm)]1 nm composite stacked phase change film, and the relationship between X-ray reflectivity and incident angle was obtained, as shown in the figure. Figure 4 As shown; [Ta5Sb] in Example 1 above 95 A phase change memory was fabricated using a 10nm / GeSb6Te(40nm)]1 nm composite stacked phase change film, and its electrical performance was tested. The results are as follows: Figure 5 The phase-change memory shown has IV and such Figure 6 The RV characteristic curve of the phase change memory is shown.

[0094] The above Figures 1-6 The test results are as follows:

[0095] Figure 1 [Ta5Sb] prepared in Example 1 95 [10nm] / GeSb6Te(20nm)]1 nanometer composite stacked phase change film, [Ta5Sb 95 [10nm] / GeSb6Te(40nm)]1 nanometer composite stacked phase change film, [Ta5Sb 95 [(20nm) / GeSb6Te(40nm)]1 nanometer composite stacked phase change film and monolayer Ta5Sb for comparison 95 The resistivity of GeSb6Te phase change material as a function of temperature is shown at a heating rate of 30℃ / min. At lower temperatures, the thin film resistance decreases slowly with increasing temperature, which is the semiconductor behavior of the alloy thin film. With further increases in temperature, the critical temperature (T0) is reached. c The resistance suddenly drops and stabilizes at a low value, indicating that the thin film has transformed from an amorphous state to a crystalline state. Monolayer Ta5Sb95 Both GeSb6Te thin films have only two resistivity states, high and low, while [Ta5Sb]... 95 [10nm] / GeSb6Te(20nm)]1 nanometer composite stacked phase change film, [Ta5Sb 95 [10nm] / GeSb6Te(40nm)]1 nanometer composite stacked phase change film, [Ta5Sb 95 In the [20nm) / GeSb6Te(40nm)]1 nm composite stacked phase change film, high, medium, and low resistance states were observed, indicating that it can be used as a multi-level storage phase change material. 95 The intermediate resistance state and the low resistance state of the (10nm) / GeSb6Te(40nm)]1 nanometer composite stacked phase change thin film differ by more than an order of magnitude, which is beneficial for logic differentiation in practical applications. Figure 1 It can also be seen that the phase transition temperature of the thin film can be controlled by adjusting the thickness ratio of the multilayer and the thickness of the single layer.

[0096] Figure 2 [Ta5Sb] prepared in Example 1 95 The relationship between the failure time and the reciprocal of temperature for a 10nm / GeSb6Te(40nm)]1nm composite stacked phase change film. Based on storage industry standards, the data retention capability of the phase change material is evaluated using the temperature at which it retains data for 10 years. Figure 2 It can be seen that the crystallization activation energy and ten-year data retention temperature of the stacked thin film during the first crystallization are similar to those of the traditional phase change material Ge2Sb2Te5 (2.34eV, 85℃). However, the crystallization activation energy and ten-year data retention temperature of the second crystallization are much higher than those of the GST material, indicating that the thin film has the advantages of strong data retention capability and stable and reliable operation, and is suitable for data storage in high-temperature environments.

[0097] Figure 3 [Ta5Sb] prepared in Example 1 95 XRD images of a 1 nm composite stacked phase change film [(10 nm) / GeSb6Te(40 nm)] were obtained after annealing the sample at different temperatures for 5 minutes. No diffraction peaks were observed in the initial deposition state, indicating that the film was amorphous. After annealing at 220 °C, diffraction peaks of the Sb rhombohedral phase appeared in the film, indicating crystallization. However, no characteristic diffraction peaks related to the GeSb6Te layer were found in the XRD pattern, suggesting that the GeSb6Te film layer remained amorphous. New diffraction peaks appeared at 280 °C and 350 °C, corresponding to the Sb rhombohedral structure in the GeSb6Te layer, indicating a second crystallization of the stacked film.

[0098] Figure 4[Ta5Sb] prepared in Example 1 95 XRR tests were performed on the 1 nm [10 nm) / GeSb6Te(40 nm)]1 nm composite stacked phase change thin film in the deposited state and after annealing. The relationship between X-ray reflectance and incident angle was obtained. The figure shows that the critical angle shifts towards larger angles after crystallization. According to the modified Bragg formula, this shift in critical angle indicates an increase in film density and a corresponding decrease in thickness, i.e., volume shrinkage. Calculations were performed on [Ta5Sb... 95 The volume change of the (10nm) / GeSb6Te(40nm)]1 thin film before and after crystallization is 4.7%, while that of the Ge2Sb2Te5 phase change material is 6.8%. This indicates that the thin film has a smaller volume shrinkage rate, which is beneficial to the stability of contact with the electrode in device applications, thereby improving the reliability of operation.

[0099] Figure 5 , Figure 6 [Ta5Sb] prepared in Example 1 95 The IV and RV characteristic curves of the phase change memory device cell of the [10nm] / GeSb6Te(40nm)]1 nm composite stacked phase change film are shown. From the IV curve of this device cell, its threshold voltage and current are 0.76 V and 30 μA, respectively. This threshold voltage is much lower than the 3.5 V of the traditional Ge2Sb2Te5 phase change material, indicating that the [Ta5Sb] of this invention... 95 The [10nm] / GeSb6Te(40nm)]1nm composite stacked phase change film exhibits lower power consumption. The RV curve of this device unit shows that, based on [Ta5Sb... 95 The phase change memory device of the (10nm) / GeSb6Te(40nm)]1 nano-composite stacked phase change film can exhibit a significant multi-stage phase change process under a 50ns pulse, indicating that the nano-composite stacked phase change film can achieve a reversible phase change under a 50ns pulse and has a relatively fast phase change rate.

[0100] comprehensive Figures 1-6 It can be seen that the nanocomposite stacked phase change film prepared by this technical solution has comprehensive properties such as high storage density, fast phase change speed and good thermal stability, which can effectively overcome many shortcomings of the existing technology.

[0101] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A nanocomposite stacked phase change thin film, characterized in that, This nanocomposite stacked phase change film is made of Ta5Sb 95 Alternating layers of thin films and GeSb6Te thin films are arranged in a stacked thin film unit, with each stacked thin film unit consisting of one layer. The structure of this nanocomposite stacked phase change thin film conforms to the following general formula: [Ta5Sb 95 [(a) / GeSb6Te(b)]1, where a and b represent Ta5Sb respectively. 95 The thicknesses of the thin film and the GeSb6Te thin film are such that 10 ≤ a ≤ 20 nm and 20 ≤ b ≤ 40 nm.

2. The nanocomposite stacked phase change thin film according to claim 1, characterized in that, The Ta5Sb 95 The thicknesses of the thin film and the GeSb6Te thin film are 10 nm and 40 nm, respectively.

3. A method for preparing a nanocomposite stacked phase change thin film as described in claim 1, characterized in that, The preparation method includes the following steps: (1) Clean the substrate; (2) Install Ta5Sb 95 For the target material and GeSb6Te target material, the mechanical pump and molecular pump were turned on in sequence to evacuate the vacuum. High-purity argon was used as the sputtering gas, and the radio frequency power, gas flow rate, sputtering pressure and substrate rotation speed were set. (3) Sputtering of target material using room temperature magnetron sputtering to prepare nanocomposite stacked phase change thin films; Step (3) includes the following sub-steps: (3a) Rotate the substrate to Ta5Sb 95 At the target site, turn on the RF sputtering power supply and sputter Ta5Sb. 95 Target material, Ta5Sb 95 After the thin film sputtering is complete, turn off Ta5Sb. 95 RF sputtering power supply for the target site; (3b) Rotate the substrate to the GeSb6Te target position, turn on the RF sputtering power supply, sputter the GeSb6Te target material, and turn off the RF sputtering power supply of the GeSb6Te target position after the GeSb6Te thin film sputtering is completed.

4. The method for preparing a nanocomposite stacked phase change thin film according to claim 3, characterized in that, The substrate is a SiO2 / Si(100) substrate.

5. The method for preparing a nanocomposite stacked phase change thin film according to claim 3, characterized in that, The Ta5Sb 95 The purity of both the target material and the GeSb6Te target material is above 99.999% atomically.

6. The method for preparing a nanocomposite stacked phase change thin film according to claim 3, characterized in that, The vacuum level after evacuation in step (2) is less than 2.5 × 10⁻⁶. -4 Pa.

7. The method for preparing a nanocomposite stacked phase change thin film according to claim 3, characterized in that, The purity of the high-purity argon gas mentioned in step (2) is above 99.999% by volume. The sputtering pressure is 0.3 Pa; The gas flow rate is 30 SCCM; The base rotation speed is 20 r / min.

8. The method for preparing a nanocomposite stacked phase change thin film according to claim 3, characterized in that, The target sputtering in step (3) uses radio frequency sputtering with a sputtering power of 20W.

9. An application of the nanocomposite stacked phase change thin film as described in claim 1, characterized in that, The nanocomposite stacked phase change film is used in the field of phase change memory.

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