High-sc-component alscn ferroelectric thin film and preparation method and application thereof

Abstract

The application provides an AlScN ferroelectric film with a high Sc component and a preparation method and application thereof, the AlScN ferroelectric film is prepared by adopting a PLD technology, and the AlScN ferroelectric film is grown on the surface of a III group nitride film with an atomic level as a buffer layer; the III group nitride film has a (002) crystal phase orientation; and the AlScN ferroelectric film has a wurtzite structure. The technical scheme of the application adopts a pulse laser deposition (PLD) technology to grow an AlN film with an atomic level flatness and a (002) orientation at a high temperature (greater than or equal to 700 DEG C), and on this basis, the growth of a high Sc doped AlScN film is carried out, so that a good matching can be formed, the Sc content is greater than 30%, and the surface of the obtained AlScN film can reach an atomic level flatness.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to an AlScN ferroelectric thin film with high Sc content, its preparation method, and its applications. Background Technology

[0002] Ferroelectric memories (FEs) are non-volatile memories that utilize the spontaneous polarization of ferroelectric thin film materials in an electric field, with two different orientations (N-polarization and M-polarization) as logic units to store data. They offer advantages such as high-speed read / write speeds, high-density integration, and radiation resistance. The most critical component of a memory is its storage cell, which determines the memory's integration density and read / write performance. For ferroelectric memories, the storage cell is typically a ferroelectric capacitor structure. Therefore, the ability to grow high-quality ferroelectric thin films to fabricate ferroelectric capacitors is crucial for improving ferroelectric memory performance. Currently, mainstream ferroelectric thin films include PZT and HfO2, but these films suffer from poor stability and incompatibility with CMOS processes. Therefore, finding a novel ferroelectric thin film is urgently needed.

[0003] In 2019, Akiyama et al. proved the ferroelectricity of AlScN, paving a new path for the development of ferroelectric memories. AlScN is obtained by doping Sc with wurtzite AlN. AlN possesses excellent physical properties such as high resistivity, high thermal conductivity, high stability, and high acoustic wave propagation rate, making it a widely used piezoelectric material. It is generally believed that AlN cannot exhibit ferroelectricity when the applied electric field strength is lower than the breakdown electric field strength of the AlN thin film dielectric. However, Sc doping lowers the energy barrier between the two polarization states, N-polarization and M-polarization, thus reducing the polarization transition electric field strength to below the breakdown electric field strength, allowing AlScN to exhibit ferroelectricity. This discovery makes it possible to use AlScN ferroelectric thin films as ferroelectric capacitor structures in ferroelectric memories. AlScN-based ferroelectric thin films have high remanent polarization and coercive field that are difficult to achieve with other ferroelectric materials. The fabrication process of AlScN is also compatible with CMOS processes and has high temperature stability, meeting the various requirements of novel ferroelectric memories.

[0004] The ferroelectricity of AlScN ferroelectric thin films is highly correlated with the crystallinity of the film; therefore, preparing high-quality ferroelectric thin films is fundamental for the fabrication of ferroelectric memory. Mainstream methods for preparing AlScN thin films include magnetron sputtering, molecular beam epitaxy (MBE), and chemical vapor deposition (MOCVD). Among existing technologies, there are publicly disclosed techniques that have grown AlScN films down to 5 nm in diameter and detected ferroelectricity, but their remanent polarization is only 23 μC / cm. 2The current level of Sc doping is far from meeting the requirements of ferroelectric memory. Generally, the higher the Sc doping ratio, the stronger the ferroelectricity of the film. Therefore, the ferroelectric performance of ferroelectric films can be improved by increasing the Sc doping concentration. However, in existing technologies, when the Sc doping ratio exceeds 30%, a rock salt structure begins to appear, which destroys the crystal quality of the wurtzite structure and thus affects the ferroelectricity. When the Sc doping ratio reaches 46%, the entire film transforms into a rock salt structure and no longer possesses ferroelectricity. For this reason, the fabrication of AlScN-based ferroelectric memory is still in the laboratory stage, and the Sc doping ratio of AlScN ferroelectric films actually used in existing technologies generally does not exceed 30%.

[0005] On the other hand, in the prior art, magnetron sputtering is usually used to grow AlScN ferroelectric thin films. For example, Chinese invention patent CN113174574A provides a method for preparing a high-quality scandium-doped aluminum nitride thin film template, which includes the following steps: 1. Preparing a substrate; 2. Depositing an AlN transition layer on the substrate using a coating technique; 3. Performing a high-temperature face-to-face heat treatment on the AlN thin film transition layer in a pure nitrogen atmosphere to form a high-quality buffer layer; 4. Depositing an AlScN thin film on the buffer layer using a reactive magnetron sputtering deposition method. In this patent, the AlN buffer layer is grown directly on the substrate. Magnetron sputtering cannot achieve high-temperature growth, which may lead to a polycrystalline structure. This could affect the quality of the AlN buffer layer, and thus the quality of the AlScN film. Although the Sc atom concentration (Sc / (Al+Sc)) reaches 40%, it is already in a polycrystalline state, and the ferroelectric properties are greatly affected. Furthermore, the patent does not evaluate the crystal phase structure of the AlScN film. On the other hand, the film growth method using magnetron sputtering results in poor film uniformity, and the surface cannot achieve atomic-level flatness, making it impossible to prepare atomically thin films. In particular, the high-temperature heat treatment after the growth of the AlN buffer layer will inevitably contaminate the film during transfer between different devices, thus affecting the growth quality of the film.

[0006] Clearly, existing technologies do not yet offer a way to improve the ferroelectricity of AlScN thin films through high Sc doping.

[0007] Therefore, this invention can improve the ferroelectricity of AlScN thin films by increasing the Sc doping concentration. By optimizing the technical solution, the ferroelectricity of AlScN thin films can be improved by increasing the Sc doping ratio without changing the wurtzite structure. This patent proposes a method for preparing AlScN ferroelectric thin films using PLD, which can achieve an Sc doping ratio exceeding 30% while maintaining excellent ferroelectricity. This method can significantly improve the ferroelectricity of AlScN thin films, which is of great significance and application value for the development of AlScN-based ferroelectric memories, and promotes the performance and further popularization of ferroelectric memories. Summary of the Invention

[0008] In view of this, in order to solve the above problems, the present invention provides an AlScN thin film with high Sc content, its preparation method and application, wherein the Sc doping content is greater than 30%, realizing the growth of high Sc doped AlScN thin film, which can form a good match and does not destroy the wurtzite structure, greatly improving the application prospects of AlScN thin film in the field of ferroelectric memory.

[0009] To achieve the above objectives, the present invention provides a method for preparing an AlScN thin film with a high Sc content, comprising: using PLD technology, based on an atomically significant group III nitride thin film as a buffer layer, growing an AlScN ferroelectric thin film on its surface; the group III nitride buffer layer having a (002) crystal phase orientation; and the AlScN ferroelectric thin film having a wurtzite structure.

[0010] Preferably, the doping ratio of Sc in the AlScN ferroelectric thin film is 30-50%; more preferably, the doping ratio of Sc is 30-50%; and most preferably, the doping ratio of Sc is 40%.

[0011] Preferably, the thickness of the AlScN ferroelectric thin film is 5–50 nm.

[0012] Preferably, the target material selected for the AlScN ferroelectric thin film includes, but is not limited to, one or more of AlScN ceramic targets, AlSc alloy targets, and Al and Sc bimetallic targets.

[0013] Preferably, the growth temperature of the AlScN ferroelectric thin film can be 200-500℃, under N2 atmosphere, with a pressure of 0.5-3Pa, a laser frequency of 1-10Hz, a laser energy of 200-500mJ, and a target-substrate distance of 50-70mm.

[0014] Preferably, the group III nitride includes any one of AlN, GaN, AlGaN, InN, and InGaN.

[0015] As a preferred technical solution, a capping layer can also be grown on the surface of the AlScN ferroelectric thin film to protect it from oxidation.

[0016] The capping layer can be a metal that serves as an electrode; preferably, the material of the capping layer can be any one of Pt, Mo, W, and Ni.

[0017] Based on the preparation technology of AlScN ferroelectric thin films with high Sc doping concentration provided by the above technical solution, the present invention also provides a stacked structure, which includes at least the buffer layer-AlScN ferroelectric thin film-capping layer provided by the above technical solution.

[0018] Furthermore, the stacked structure includes a substrate, an isolation layer, a bottom electrode, a buffer layer, an AlScN ferroelectric thin film, a top electrode, and a capping layer.

[0019] In some preferred embodiments, the PLD system can directly grow a stacked structure in one step, the stacked structure of which, from bottom to top, includes TiN-Pt-AlN-AlScN-TiN-Pt.

[0020] Furthermore, the fabrication method of the stacked structure adopts the PLD method throughout and forms a film in one step, and the specific steps include:

[0021] S1. Provide a substrate;

[0022] S2. An isolation layer (or adhesion layer) is grown on the surface of the substrate;

[0023] S3. A bottom electrode film is grown on the surface of the isolation layer;

[0024] S4. A buffer layer is grown on the surface of the bottom electrode film;

[0025] S5. An AlScN ferroelectric thin film is grown on the surface of the buffer layer;

[0026] S6. A top electrode is grown on the surface of the AlScN ferroelectric thin film;

[0027] S7. A capping layer is grown on the surface of the top electrode.

[0028] Among them, the materials and processes of the top electrode and the bottom electrode may be the same or different; the materials and processes of the capping layer and the isolation layer may be the same or different.

[0029] The buffer layer is the group III nitride film.

[0030] Preferably, the thickness of the group III nitride film is 2 to 20 nm.

[0031] Preferably, the growth conditions for the group III nitrides include a temperature of 650–800°C, an N2 atmosphere, a pressure of 0–5 Pa, a laser frequency of 1–10 Hz, a laser energy of 200–500 mJ, and a target-substrate distance of 50–70 mm.

[0032] Preferably, the substrate is made of a material suitable for depositing semiconductor thin films, specifically including any one of Si(100), Si(111), sapphire, gallium nitride (GaN), silicon carbide (SiC), and glass.

[0033] Preferably, the material of the covering layer and / or the insulating layer includes TiN or TaN.

[0034] Preferably, the thickness of the isolation layer is 1–20 nm.

[0035] Preferably, the growth temperature of the isolation layer is 650–800℃, the gas pressure is 0.5–3Pa in an N2 atmosphere, the laser frequency is 1–10Hz, the laser energy is 200–500mJ, and the target-substrate distance is 50–70mm.

[0036] Preferably, the bottom electrode and the top electrode are made of materials that can be used as electrodes, including any one of Pt, Mo, W, and Ni.

[0037] Preferably, the thickness of the top electrode and the capping layer is 20-200 nm, the growth temperature is 20-400 °C, the gas pressure is 0.5-3 Pa in an N2 atmosphere, the laser frequency is 1-10 Hz, the laser energy is 200-500 mJ, and the target-substrate distance is 50-70 mm.

[0038] Preferably, the bottom electrode film and the isolation layer have the same crystal orientation.

[0039] Preferably, the isolation layer is a (111) crystal phase, and the bottom electrode film grown on the surface of the isolation layer also has the same (111) crystal orientation.

[0040] The stacked structure provided by the above technical solution can be applied to AlScN-based ferroelectric memories.

[0041] The beneficial technical effects obtained by this invention are as follows:

[0042] 1. The technical solution of this invention uses pulsed laser deposition (PLD) technology to grow an AlN thin film with (002) orientation and atomically smooth surface at high temperature (≥700℃) as a buffer layer. On this basis, a highly Sc-doped AlScN thin film is grown, which can form a good match. The Sc content is greater than 30%, and the doping concentration can reach up to 50%. The surface of the obtained AlScN thin film can reach atomically smooth surface. In particular, the wurtzite structure of the AlScN ferroelectric thin film allows it to maintain good ferroelectric properties.

[0043] 2. The stacked structure prepared by the technical solution of the present invention includes an AlScN ferroelectric thin film with a high Sc doping concentration, wherein AlScN has a wurtzite structure that can maintain high ferroelectricity. This realizes the method of improving the ferroelectric performance of the ferroelectric thin film by increasing the Sc doping concentration, making it more competitive in the field of ferroelectric memory.

[0044] 3. The technical solution of this invention is based on PLD technology to realize the entire film growth process, which can achieve film formation in one step without exposure to the environment, thereby reducing the pollution of the film by the atmospheric environment.

[0045] 4. The AlScN thin film prepared by the pulsed laser deposition (PLD) system of the present invention can perform stoichiometric transfer and same-component deposition, with good composition preservation, and can prepare nitrides of any proportion; moreover, the film quality is higher and the surface is smoother than that of magnetron sputtering; and compared with MBE, the film growth rate is faster and the cost is lower. Attached Figure Description

[0046] Figure 1 The process flow diagram for preparing highly Sc-doped AlScN ferroelectric thin films provided in Example 1 of this invention.

[0047] Figure 2 XRD diffraction pattern of the AlScN ferroelectric thin film prepared in Example 1 of this invention.

[0048] Figure 3 A schematic diagram of the PLD system of this invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0050] This invention provides a method for preparing AlScN ferroelectric thin films and stacked structures with high Sc content, which is based on the PLD method. The PLD method used in this invention is based on a PLD system, which mainly includes two parts: a light source system and a vacuum growth system (e.g., ...). Figure 3 (As shown).

[0051] Specifically, see Figure 3 The light source system consists of a pulsed excimer laser and a focusing optical path system, while the vacuum growth system consists of a sample introduction chamber and an epitaxial growth chamber. The laser is a German-made ComPexPro201 series krypton fluoride (KrF) pulsed excimer laser with high pulse energy. The focusing optical path system consists of an optical mirror and a focusing lens, which can realize the dynamic control of the energy focusing and incident direction of the incident laser beam.

[0052] The vacuum growth system includes an epitaxial growth chamber and a sample introduction chamber. The epitaxial growth chamber is equipped with four target trays, allowing for in-situ sample processing (e.g., heating, argon ion bombardment), achieving ultra-high vacuum (vacuum level better than 2×10⁻⁶ after baking and degassing). -8 pa) Epitaxial growth of thin films; the four target trays in the epitaxial growth chamber are respectively equipped with Al0.6Sc0.4N ceramic target, AlN ceramic target, Pt metal target and TiN target, which ensures that the entire stacked structure can be grown in a vacuum environment in one go without being exposed to the atmosphere.

[0053] The sample loading chamber is equipped with a sample library and a sample heating stage. The sample library can hold 6 samples or targets, which can reduce the influence of vacuum during the transfer of targets and samples. The sample heating stage has an adjustable heating temperature range from room temperature to 800°C, which can realize the heating growth and in-situ annealing of thin film samples. The differential high-energy electron diffractometer (RHEED) on the PLD system can accurately control the growth of atomic-layer epitaxial thin films in real time and in situ, and observe the surface structure of the samples.

[0054] The use of the PLD system described above for the preparation of AlScN thin films and stacked structures enables one-time growth without the need for transfer between different devices, thus avoiding the impact of atmospheric pollution on film quality.

[0055] Specifically, the high Sc content AlScN ferroelectric thin film provided by the present invention is based on a group III nitride thin film with atomic scale as a buffer layer, on which an AlScN ferroelectric thin film is grown; wherein, the group III nitride has a (002) crystal phase orientation; and the AlScN ferroelectric thin film has a wurtzite structure.

[0056] In some specific embodiments, the Sc doping ratio in the AlScN ferroelectric thin film is 30% to 50%. Unless otherwise specified, the Sc doping concentration or doping ratio mentioned in this invention refers to the ratio or concentration of Sc / (Al+Sc).

[0057] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0058] Example 1

[0059] This embodiment provides a PLD system, mainly comprising a light source system and a vacuum growth system. Specifically, the light source system consists of a pulsed excimer laser and a focusing optical path system, while the vacuum growth system consists of a sample introduction chamber and an epitaxial growth chamber. The laser is a German-made ComPexPro201 series krypton fluoride (KrF) pulsed excimer laser, and the focusing optical path system consists of an optical mirror and a focusing lens, enabling dynamic control of the energy focusing and incident direction of the incident laser beam.

[0060] The vacuum growth system includes an epitaxial growth chamber and a sample introduction chamber. The epitaxial growth chamber is equipped with four target trays, allowing for in-situ sample processing (e.g., heating, argon ion bombardment), achieving ultra-high vacuum (vacuum level better than 2×10⁻⁶ after baking and degassing). -8 Pa) Epitaxial growth of thin films; the four target trays in the epitaxial growth chamber are respectively equipped with Al 0.6 Sc 0.4 The use of N ceramic targets, AlN ceramic targets, Pt metal targets, and TiN targets ensures that the entire laminated structure can be grown in a vacuum environment in one go, without needing to be exposed to the atmosphere.

[0061] This embodiment provides a stacked structure, see reference. Figure 1 The specific preparation methods include:

[0062] 1. Provide a substrate; the substrate material can be selected from those used to deposit semiconductor thin films, specifically including any one of Si(100), Si(111), sapphire, gallium nitride (GaN), silicon carbide (SiC), and glass; as a preferred embodiment, this embodiment selects SiC as the substrate material.

[0063] 2.2. Provide an isolation layer; first, grow a 20nm TiN layer on the substrate as an isolation layer and adhesion layer. The growth temperature is 700℃, the N2 pressure is 2.5Pa, the pulsed laser frequency is 2Hz, the laser energy is 350mJ, the target-substrate distance is 57mm, the growth time is 120min, and after the growth is completed, anneal in situ for 60min.

[0064] 3. Provide a bottom electrode thin film layer; grow a 20nm Pt film on the substrate surface as a bottom electrode thin film, rotate the target revolution rod to align the Pt metal target with the sample stage, the growth temperature is 700℃, the N2 gas pressure is 2.5Pa, the pulse laser frequency is 2Hz, the laser energy is 350mJ, the target-substrate distance is 57mm, the growth time is 120min, and after the growth is completed, anneal in situ for 60min. The metal thin film grown on the (111) crystal phase is also (111) oriented.

[0065] 4. Provide a buffer layer; grow a 2-3 nm AlN layer on the surface of the bottom electrode film as a buffer layer, rotate the target rotation rod to align the AlN ceramic target with the sample stage, the growth temperature is 650℃, the N2 gas pressure is 2.5 Pa, the pulsed laser frequency is 2 Hz, the laser energy is 350 mJ, the target-substrate distance is 57 mm, the growth time is 5 min, and after the growth is completed, anneal in situ for 60 min.

[0066] 5. Provide a ferroelectric thin film layer; grow a 20nm AlScN ferroelectric thin film on the surface of the buffer layer, rotate the target orbital rod, and then... 0.6 5c 0.4 The N-target was aligned with the sample stage, the growth temperature was 400℃, the N2 gas pressure was 1Pa, the pulsed laser frequency was 2Hz, the laser energy was 350mJ, the target-substrate distance was 57mm, and in-situ annealing was performed for 60min after growth. The AlScN wurtzite structure grown on the (002) crystal phase is not easily destroyed, so the doping concentration of Sc element can be increased.

[0067] 5. Provide a capping layer and a top electrode. 20 nm TiN and 20 nm Pt are sequentially grown on the surface of the AlScN ferroelectric thin film as a capping layer and a top electrode. The growth temperature is room temperature, the N2 gas pressure is 1 Pa, the pulsed laser frequency is 2 Hz, the laser energy is 350 mJ, the target-substrate distance is 57 mm, and the film is annealed in situ for 60 min after growth.

[0068] Using the above technical solution, a memory device with a stacked structure can be grown directly in one step. The stacked structure consists of TiN-Pt-AlN-AlScN-TiN-Pt (excluding the substrate) from bottom to top.

[0069] See Figure 2 The figure shows the XRD pattern of Example 1. The XRD peaks of AlScN and AlN are both around 36°. The peaks of AlScN and AlN are shown to overlap in the figure (or the XRD peak of AlScN covers the XRD peak of AlN).

[0070] According to the XRD diffraction pattern, TiN grown under these conditions has a (111) crystal phase, while the AlN layer grown on the TiN surface has a (002) crystal phase; AlScN grown on the (002) crystal phase of AlN exhibits a wurtzite structure with a (002) orientation.

[0071] Example 2

[0072] This embodiment provides a stacked structure, wherein

[0073] 1. Provide a substrate; the substrate material is SiC.

[0074] 2. Provide an isolation layer; first grow a 20nm TiN layer on the substrate as an isolation layer and adhesion layer. The growth temperature is 650℃, the N2 pressure is 2Pa, the pulsed laser frequency is 2Hz, the laser energy is 350mJ, the target-substrate distance is 57mm, the growth time is 120min, and after the growth is completed, anneal in situ for 60min.

[0075] 3. Provide a bottom electrode thin film layer; grow a 20nm Pt film on the substrate surface as a bottom electrode thin film, rotate the target revolution rod to align the Pt metal target with the sample stage, the growth temperature is 700℃, the N2 gas pressure is 2.5Pa, the pulse laser frequency is 2Hz, the laser energy is 350mJ, the target-substrate distance is 57mm, the growth time is 120min, and after the growth is completed, anneal in situ for 60min. The metal thin film grown on the (111) crystal phase is also (111) oriented.

[0076] 4. Provide a buffer layer; grow a 2-3 nm AlN layer on the surface of the bottom electrode film as a buffer layer, rotate the target rotation rod to align the AlN ceramic target with the sample stage, the growth temperature is 800℃, the N2 gas pressure is 5 Pa, the pulse laser frequency is 8 Hz, the laser energy is 500 mJ, the target-substrate distance is 60 mm, the growth time is 5 min, and after the growth is completed, anneal in situ for 60 min.

[0077] 5. Provide a ferroelectric thin film layer; grow a 20nm AlScN ferroelectric thin film on the surface of the buffer layer, rotate the target orbital rod, and then... 0.5 Sc 0.5 The N-target was aligned with the sample stage, the growth temperature was 400℃, the N2 gas pressure was 1Pa, the pulsed laser frequency was 2Hz, the laser energy was 350mJ, the target-substrate distance was 57mm, and in-situ annealing was performed for 60min after growth. The AlScN wurtzite structure grown on the (002) crystal phase is not easily destroyed, so the doping concentration of Sc element can be increased.

[0078] 5. Provide capping layer and top electrode; grow 20 nm TiN and 20 nm Pt sequentially on the surface of AlScN ferroelectric thin film as capping layer and top electrode, respectively. The growth temperature is room temperature, N2 pressure is 1 Pa, pulsed laser frequency is 2 Hz, laser energy is 350 mJ, target-substrate distance is 57 mm, and in-situ annealing is performed after growth.

[0079] In this embodiment, XRD diffraction patterns were obtained, showing that the same diffraction pattern as in Example 1. This indicates that the AlScN wurtzite structure grown on the (002) crystal phase is not easily destroyed, and therefore the doping concentration of Sc can be increased.

[0080] Based on the above technical solution, a ferroelectric thin film is prepared on the surface of a (002) oriented group III nitride thin film by PLD method. The AlScN wurtzite structure is not easily destroyed, so a ferroelectric thin film with a high doping concentration of Sc element can be obtained and excellent ferroelectric performance can be maintained. Even when the doping concentration (Sc / (Sc+Al)) reaches 50%, the AlScN wurtzite structure of the ferroelectric thin film can still be maintained, thus providing support for maintaining good ferroelectric performance in capacitors and ferroelectric memories.

[0081] In particular, the stacked structure prepared using the technical solution of the present invention includes an AlScN ferroelectric thin film with a high Sc doping concentration, wherein the AlScN has a wurtzite structure that can maintain high ferroelectricity. This realizes the method of improving the ferroelectric performance of the ferroelectric thin film by increasing the doping concentration of Sc, making it more competitive in the field of ferroelectric storage.

[0082] The above are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any changes, modifications, substitutions, integrations, and parameter alterations to these embodiments within the spirit and principles of the present invention, achieved through conventional substitutions or by achieving the same function without departing from the principles and spirit of the present invention, fall within the scope of protection of the present invention.

Claims

1. A method for preparing an AlScN ferroelectric thin film with a high Sc content, comprising: Using PLD technology, an AlScN ferroelectric thin film is grown on the surface of an atomically flat group III nitride film as a buffer layer; wherein the group III nitride has a (002) crystal phase orientation; and the AlScN ferroelectric thin film has a wurtzite structure. The growth temperature of the AlScN ferroelectric thin film is 200-500℃, under N2 atmosphere, with a pressure of 0.5-3Pa, a laser frequency of 1-10Hz, a laser energy of 200-500mJ, and a target-substrate distance of 50-70mm. The growth conditions for the buffer layer include a temperature of 650–800℃, an N2 atmosphere, a pressure of 0–5Pa, a laser frequency of 1–10Hz, a laser energy of 200–500mJ, and a target-substrate distance of 50–70mm.

2. The method for preparing AlScN ferroelectric thin films with high Sc content according to claim 1, characterized in that, In the AlScN ferroelectric thin film, the doping ratio of Sc is 30% to 50%; And / or, the thickness of the AlScN ferroelectric thin film is 5–50 nm; And / or, the target material selected for the AlScN ferroelectric thin film includes one or more of AlScN ceramic targets, AlSc alloy targets, and Al,Sc bimetallic targets; And / or, the group III nitrides include any one of AlN, GaN, AlGaN, InN, and InGaN.

3. The method for preparing AlScN ferroelectric thin films with high Sc content according to claim 1 or 2, characterized in that, A capping layer is grown on the surface of the AlScN ferroelectric thin film to protect it from oxidation. And / or, the material of the covering layer includes TiN or TaN.

4. An AlScN ferroelectric thin film, prepared by the preparation method according to any one of claims 1-3.

5. A multilayer structure comprising at least the AlScN ferroelectric thin film as described in claim 4.

6. The stacked structure according to claim 5, comprising a substrate, an isolation layer, a bottom electrode, a buffer layer, an AlScN ferroelectric thin film, a capping layer, and a top electrode; And / or, the buffer layer is a group III nitride film; And / or, the material of the covering layer includes TiN or TaN.

7. A method for preparing a laminated structure as described in claim 5 or 6, based on the PLD method, using a PLD system throughout the process and forming a film in one step, comprising the following steps: S1. Provide a substrate; S2. An isolation layer or an adhesion layer is grown on the surface of the substrate; S3. A bottom electrode film is grown on the surface of the isolation layer; S4. A buffer layer is grown on the surface of the bottom electrode film; S5. An AlScN ferroelectric thin film is grown on the surface of the buffer layer; S6. A top electrode is grown on the surface of the AlScN ferroelectric thin film; S7. A capping layer is grown on the surface of the top electrode; The top electrode and the bottom electrode may be made of the same material or have different manufacturing processes; The materials and processes used for the covering layer and the isolation layer may be the same or different; And / or, the buffer layer is a group III nitride film.

8. The method for preparing the laminated structure according to claim 7, characterized in that, The substrate material is selected from thin film materials used to deposit semiconductors, specifically including any one of Si(100), Si(111), sapphire, gallium nitride (GaN), silicon carbide (SiC), and glass. And / or, the material of the capping layer and / or the insulating layer includes TiN or TaN; And / or, the thickness of the isolation layer is 1–20 nm; And / or, the growth temperature of the isolation layer is 650-800℃, under N2 atmosphere, with a gas pressure of 0.5-3Pa, a laser frequency of 1-10Hz, a laser energy of 200-500mJ, and a target-substrate distance of 50-70mm; And / or, the materials of the bottom electrode and the top electrode are materials that can be used as electrodes, including any one of Pt, Mo, W, and Ni; And / or, the thickness of the top electrode and the capping layer is 20-200 nm, the growth temperature is 20-400 °C, the gas pressure is 0.5-3 Pa in N2 atmosphere, the laser frequency is 1-10 Hz, the laser energy is 200-500 mJ, and the target-substrate distance is 50-70 mm. And / or, the isolation layer is a (111) crystal phase, and the bottom electrode film grown on the surface of the isolation layer has the same (111) crystal orientation; And / or, the material of the top electrode and / or the bottom electrode includes TiN or TaN; And / or, the material of the covering layer includes any one of Pt, Mo, W, and Ni.

9. A ferroelectric memory, comprising at least the AlScN ferroelectric thin film as described in claim 4 or the stacked structure as described in claim 5 or 6.

10. A ferroelectric capacitor, comprising at least the AlScN ferroelectric thin film as described in claim 4 or the multilayer structure as described in claim 5 or 6.

Images