Preparation method and system of AlScN thin film

Abstract

The application relates to a preparation method and a preparation system of an AlScN film. The preparation method comprises the following steps: providing a substrate; pre-treating the substrate to form a platinum electrode layer on the substrate; placing the substrate in a reaction chamber, pre-treating the reaction chamber, and changing the pressure and temperature of the reaction chamber into predetermined values; introducing a precursor gas into the reaction chamber; and circulating the precursor gas multiple times to deposit a film with a target thickness on the surface of the platinum electrode layer. The preparation system comprises a reaction chamber, a heating carrier rotatably arranged in the reaction chamber and used for carrying the substrate, a precursor pipeline comprising a first pipeline and a second pipeline and a carrier gas pipeline, and a reaction gas pipeline in communication with the reaction chamber and used for introducing ammonia into the reaction chamber. The precursor gas of the application does not introduce impurities, and high-temperature annealing treatment is not needed to realize a crystalline state.

Description

Technical Field

[0001] This invention relates to the field of thin film material preparation technology, and in particular to a method and system for preparing AlScN thin films. Background Technology

[0002] The current mainstream fabrication technology for AlScN thin films is still magnetron sputtering, which is mainly aimed at the filter market.

[0003] In existing technologies, due to limitations in reaction kinetics, the energy required for thermal atomic layer deposition (ALD) is insufficient to achieve crystalline growth of AlScN thin films. This issue has become a core bottleneck hindering its industrial application in memory devices. In addition, existing ALD techniques for preparing AlScN thin films face several other key challenges: firstly, there is a lack of suitable Sc precursors; commercially available Sc precursors often contain impurities such as Cl and O, which can lead to residual impurities in the film and reduce device stability. Secondly, AlScN films deposited via ALD typically require subsequent high-temperature (above 600°C) annealing to achieve a crystalline state. This not only increases process complexity but may also cause interfacial diffusion problems between the metal electrode and the dielectric film, resulting in device leakage.

[0004] Therefore, it is necessary to provide a new method and system for preparing AlScN thin films to solve the above-mentioned problems in the prior art. Summary of the Invention

[0005] The technical problem to be solved by this application is how to provide a method and system for preparing AlScN thin films that do not introduce impurities with the precursor gas and do not require high-temperature annealing to achieve a crystalline state.

[0006] To address the aforementioned technical problems, according to embodiments of this application, a method for preparing an AlScN thin film is provided, comprising the following steps: providing a substrate; pretreating the substrate to form a platinum electrode layer on the substrate; placing the substrate in a reaction chamber and pretreating the reaction chamber to set the pressure and temperature of the reaction chamber to predetermined values; introducing a precursor gas into the reaction chamber to provide aluminum atoms and scandium atoms to the platinum electrode layer; and circulating the precursor gas multiple times to deposit a thin film of a target thickness on the surface of the platinum electrode layer.

[0007] According to an embodiment of this application, the pretreatment of the substrate to form a platinum electrode layer on the substrate includes: etching the substrate using an inert gas mixed plasma to form an etched surface; forming the platinum electrode layer on the etched surface by a magnetron sputtering process; and heat-treating the platinum electrode layer to stabilize its crystallization.

[0008] According to an embodiment of this application, the etching of the substrate using an inert gas mixed plasma to form an etched surface includes mixing argon and nitrogen in a 1:1 ratio and exciting them to form a mixed plasma to etch the substrate; the etching power is 125-175W and the etching time is 3-7min.

[0009] According to an embodiment of this application, the step of introducing a precursor gas into the reaction chamber includes: using an inert gas as a carrier gas, pulse-introducing trimethylaluminum gas into the reaction chamber to provide aluminum atoms to the platinum electrode layer; using an inert gas as a carrier gas to... A gas pulse is introduced into the reaction chamber to provide scandium atoms to the platinum electrode layer.

[0010] According to an embodiment of this application, the multiple cycles of the precursor gas to deposit a thin film of the target thickness on the surface of the platinum electrode layer includes: cyclically introducing trimethylaluminum gas to form an aluminum nitride layer; cyclically introducing... Gas, forming a scandium nitride layer; trimethylaluminum gas is repeatedly introduced and... The gas step forms a thin film of the target thickness.

[0011] According to an embodiment of this application, the step of circulating trimethylaluminum gas to form an aluminum nitride layer includes: pulsedly introducing trimethylaluminum gas into the reaction chamber for 0.1-0.5 s; purging with a carrier gas at a flow rate of 500-700 sccm for 1-5 s; pulsedly introducing ammonia gas into the reaction chamber for 1-3 s; purging again with a carrier gas at a flow rate of 500-700 sccm for 55-65 s; repeating the above steps until the aluminum nitride lattice unit layers are stacked to a set thickness to form the aluminum nitride layer.

[0012] According to an embodiment of this application, the cyclic input... Gas, forming a scandium nitride layer, including pulsed injection into the reaction chamber. Gas; pulse duration 1-3s; purging with carrier gas; carrier gas flow rate 500-700 sccm, purging time 5-10s; ammonia gas pulsed into the reaction chamber; pulse duration 1-3s; purging again with carrier gas to form scandium nitride lattice unit layer; carrier gas flow rate 500-700 sccm, purging time 15-30s; repeat the above steps until the scandium nitride lattice unit layer is stacked to a set thickness to form the scandium nitride layer.

[0013] According to an embodiment of this application, the process of repeatedly circulating the precursor gas to deposit a thin film of the target thickness on the surface of the platinum electrode layer further includes: maintaining the temperature of the reaction chamber constant, introducing an inert gas into the reaction chamber for 10-50 minutes; reducing the temperature inside the reaction chamber to room temperature at a set cooling rate, and removing the substrate.

[0014] According to an embodiment of this application, the method further includes, after the trimethylaluminum gas is circulated to form an aluminum nitride layer, closing the control valve of the reaction chamber, maintaining the pressure and temperature of the reaction chamber constant for 1-3 minutes, to allow atomic diffusion on the surface of the aluminum nitride layer; the circulated gas... After the gas forms a scandium nitride layer, the control valve of the reaction chamber is closed, and the pressure and temperature of the reaction chamber are kept constant for 1-3 minutes to allow atomic diffusion on the surface of the scandium nitride layer.

[0015] An AlScN thin film preparation system for implementing the above-described preparation method, the preparation system comprising a reaction chamber; a heating carrier rotatably disposed within the reaction chamber for supporting the substrate; and a precursor pipeline including a first pipeline, a second pipeline, and a carrier gas pipeline; one end of the first pipeline is connected to the reaction chamber, and the other end is used to place trimethylaluminum gas from the precursor gas; one end of the second pipeline is connected to the reaction chamber, and the other end is used to place trimethylaluminum gas from the precursor gas... Gas; the carrier gas pipeline is connected to the side wall of the first pipeline and the side wall of the second pipeline, and is used to introduce carrier gas into the first pipeline or the second pipeline, so that the trimethylaluminum gas in the first pipeline enters the reaction chamber, or the trimethylaluminum gas in the second pipeline... Gas enters the reaction chamber; a reaction gas pipeline is connected to the reaction chamber to introduce ammonia gas into the reaction chamber.

[0016] By adopting the above technical solution, an ultra-cyclic process is formed by alternating deposition of aluminum nitride and scandium nitride layers. The thickness and composition of the film are controlled by using a precursor free of impurities such as chlorine, oxygen, sulfur, and fluorine. After each layer is deposited, the inlet valve is closed for in-situ micro-annealing to repair defects and release stress layer by layer. This process is used to cyclically form an AlScN film of the target thickness. This results in a crystalline aluminum nitride and scandium nitride film with uniform thickness, precise composition, and extremely low impurities. At the same time, the precursor gas does not introduce impurities, reducing the complexity of the process. Furthermore, it eliminates the need for subsequent high-temperature annealing to achieve crystallization, thus realizing the low-temperature growth of crystalline AlScN films. Attached Figure Description

[0017] Figure 1 This is a step diagram illustrating a method for preparing an AlScN thin film according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the main structure of an AlScN thin film preparation system according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the chemical structure of trimethylaluminum according to an embodiment of the present invention.

[0020] Figure 4 This is one embodiment of the present invention. A schematic diagram of its chemical structure.

[0021] Figure 5 This is a thickness distribution diagram of an AlN thin film at 30 nm according to an embodiment of the present invention.

[0022] Figure 6 This is a distribution diagram of the refractive index n value of an AlN thin film at 30 nm according to an embodiment of the present invention.

[0023] Figure 7 This is a thickness distribution diagram of an AlScN thin film at 30 nm according to an embodiment of the present invention.

[0024] Figure 8 This is a distribution diagram of the refractive index n value of an AlScN thin film at 30 nm according to an embodiment of the present invention.

[0025] Figure 9 This is an XPS spectrum of an AlScN thin film according to an embodiment of the present invention. The horizontal axis represents the binding energy in eV; the vertical axis represents the photoelectron intensity in counts / s.

[0026] Figure 10 The AlN thin film and the embodiment of the present invention X-ray diffraction (XRD) pattern of the thin film; the horizontal axis represents the diffraction angle, specifically the 2θ angle, and the vertical axis represents the diffraction intensity. The black curve represents the AlN thin film, and the red curve represents... film.

[0027] Figure 11 This is a piezoelectric force microscopy (PFM) phase image of the AlScN thin film according to an embodiment of the present invention.

[0028] Figure label:

[0029] 100. Reaction chamber; 110. Heating carrier; 210. First pipeline; 211. First control valve; 220. Second pipeline; 221. Second control valve; 230. Carrier gas pipeline; 231. Third control valve; 310. Reaction gas pipeline; 400. Substrate. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0031] The following is in conjunction with the appendix Figures 1-11 The specific embodiments of the present invention will be further described in detail below.

[0032] The present invention provides a method and system for preparing AlScN thin films. The method is used to prepare AlScN (aluminum scandium nitride) thin films, and the system is used to implement the method for preparing AlScN (aluminum scandium nitride) thin films. The system includes a reaction chamber 100.

[0033] Heating carrier 110 is rotatably disposed in reaction chamber 100 and is used to support substrate 400;

[0034] The precursor pipeline includes a first pipeline 210, a second pipeline 220, and a carrier gas pipeline 230; one end of the first pipeline 210 is connected to the reaction chamber 100, and the other end is used to place trimethylaluminum gas from the precursor gas; one end of the second pipeline 220 is connected to the reaction chamber 100, and the other end is used to place trimethylaluminum gas from the precursor gas. Gas; Carrier gas pipeline 230 connects to the side wall of the first pipeline 210 and the side wall of the second pipeline 220, and is used to introduce carrier gas into the first pipeline 210 or the second pipeline 220, so that the trimethylaluminum gas in the first pipeline 210 enters the reaction chamber 100, or the gas in the second pipeline 220... Gas enters the reaction chamber at 100°C;

[0035] The reaction gas pipeline 310 is connected to the reaction chamber 100 to introduce ammonia gas into the reaction chamber 100.

[0036] In some specific embodiments, the heating carrier 110 is disposed at the bottom of the reaction chamber 100 by means of dynamic sealing, with a part of it placed inside the reaction chamber 100 and another part placed outside the reaction chamber 100; a rotary drive device is also provided outside the reaction chamber 100, and the rotary drive device is connected to the part of the heating carrier 110 placed outside the reaction chamber 100 to drive the heating carrier 110 to rotate. This is known to those skilled in the art and will not be described in detail here.

[0037] In some specific embodiments, one end of the first pipe 210 is located at the top of the reaction chamber 100. Its installation method can be snap-fit ​​or bolted, etc., without limitation, as long as the position of the first pipe 210 at the top of the reaction chamber 100 remains unchanged and it can supply gas into the reaction chamber 100. The other end of the first pipe 210 is equipped with a gas cylinder, which is connected to the first pipe 210, allowing gas from the gas cylinder to enter the first pipe 210. The gas cylinder is equipped with a first control valve 211 to open or close the gas cylinder. Specifically, the gas cylinder at the end of the first pipe 210 is used to store trimethylaluminum gas; more specifically, the trimethylaluminum gas is a vapor gas.

[0038] In some specific embodiments, one end of the second pipeline 220 is located at the top of the reaction chamber 100. Its installation method can be snap-fit ​​or bolted, etc., without limitation, as long as the position of the second pipeline 220 at the top of the reaction chamber 100 remains unchanged and it can supply gas into the reaction chamber 100. The other end of the second pipeline 220 is equipped with a gas cylinder, which is connected to the second pipeline 220, allowing gas from the gas cylinder to enter the second pipeline 220. The gas cylinder is equipped with a second control valve 221 to open or close the gas cylinder. Specifically, the gas cylinder at the end of the second pipeline 220 is used to store... Gas; more specifically, The gas is a vapor.

[0039] In some specific embodiments, the carrier gas pipeline 230 is simultaneously connected to both the first pipeline 210 and the second pipeline 220. A third control valve 231 is installed on the carrier gas pipeline 230, positioned between the first pipeline 210 and the second pipeline 220. During the process of introducing the precursor gas into the reaction chamber 100, the first control valve 211 is opened, while the second control valve 221 and the third control valve 231 are closed. At this time, the carrier gas is introduced. Since trimethylaluminum gas is a vapor, it enters the first pipeline 210 and comes into contact with the carrier gas, which carries the trimethylaluminum gas into the reaction chamber 100. The first control valve 211 is then closed, while the second control valve 221 and the third control valve 231 are opened. At this time, the carrier gas is introduced, and since... The gas is a vapor, therefore The gas will enter the first pipe 210 and come into contact with the carrier gas, which will carry... The gas enters the reaction chamber 100.

[0040] In some embodiments, one end of the reaction gas pipeline 310 is located in the reaction chamber 100. The pipeline can be installed by snap-fit ​​or bolt fixing, etc., which is not limited here. The main purpose is that the position of the reaction gas pipeline 310 in the reaction chamber 100 does not change and can introduce gas into the reaction chamber 100. The other end of the reaction gas pipeline 310 is connected to a device that provides ammonia gas to introduce ammonia gas into the reaction chamber 100.

[0041] The preparation method includes the following steps:

[0042] S1, Provides a 400-degree substrate;

[0043] S2. Pre-treat the substrate 400 to form a platinum electrode layer on the substrate 400;

[0044] S3. Place the substrate 400 in the reaction chamber 100 and pre-treat the reaction chamber 100 to make the pressure and temperature of the reaction chamber change to predetermined values.

[0045] S4. Introduce a precursor gas into the reaction chamber 100 to provide aluminum atoms and scandium atoms to the platinum electrode layer;

[0046] S5. The precursor gas is repeatedly circulated to deposit a thin film of the target thickness on the surface of the platinum electrode layer.

[0047] In some embodiments, a substrate 400 needs to be prepared before the AlScN thin film is fabricated. The substrate 400 can be made of sapphire or silicon; there is no limitation on this, and different substrate 400 materials are selected according to different fabrication requirements during the actual fabrication process. Specifically, during the preparation of the substrate 400, it is necessary to ensure that the surface of the substrate 400 is chemically clean. For example, it can be sequentially cleaned with acetone, isopropanol, and ultrasonically cleaned, followed by drying with nitrogen gas. Simultaneously, the selected substrate 400 must be lattice-compatible with the subsequent platinum electrode. Here, sapphire is used as an example for illustration.

[0048] In some embodiments, after the substrate 400 is prepared, it is necessary to pre-treat the prepared substrate 400 to form a platinum electrode layer on the surface of the substrate 400. Subsequently, the AlScN film is formed on the surface of the platinum electrode layer. Taking advantage of the high lattice matching between the (111) crystal plane of the platinum electrode on the sapphire substrate 400 and the AlScN wurtzite (002) crystal plane, the AlScN film is spontaneously formed with sharp wurtzite (002) diffraction peaks through crystal induction, thus avoiding the damage to device performance caused by high temperature heat treatment.

[0049] In some embodiments, after the platinum electrode layer is prepared, the reaction chamber 100 needs to be pretreated to bring the pressure and temperature of the reaction chamber to predetermined values. Specifically, during the pretreatment of the reaction chamber 100, the substrate 400 is first fixed on the heating carrier 110 inside the reaction chamber 100. The heating carrier 110 supports and heats the substrate 400 to bring its temperature to the required reaction temperature. Simultaneously, all control valves in the reaction chamber 100 are closed, and the reaction chamber 100 is evacuated to reduce the pressure inside to below 2 Torr. At the same time, the gas cylinders at the ends of the first pipeline 210 and the second pipeline 220 are heated to a temperature of 14°C. The temperature range is 0℃-180℃, but it can also be 170℃ or other temperatures; no specific limitation is imposed here, and the setting is made according to the actual usage requirements. Simultaneously, the precursor pipeline and the reactant gas pipeline 310 need to be heated to a temperature greater than 200℃, specifically 240℃ or 300℃; no specific limitation is imposed here, and different temperatures are selected according to different preparation requirements during the actual thin film preparation process. The heating carrier 110 is controlled to heat the reaction chamber 100 to a temperature of 340℃-400℃, specifically 340℃, 350℃ or 400℃; no specific limitation is imposed here, and the setting is made according to the actual usage requirements. In addition, a nitrogen source reactant gas is required; in this embodiment, the nitrogen source reactant gas is selected as... (Ammonia).

[0050] In some embodiments, when the temperature and pressure inside the reaction chamber 100 reach the set values, a precursor gas is introduced into the reaction chamber 100 and the precursor gas is circulated multiple times, thereby depositing an AlScN thin film of the target thickness on the surface of the platinum electrode layer.

[0051] In some specific embodiments, the substrate 400 is pretreated to form a platinum electrode layer on the substrate 400, including:

[0052] The substrate 400 is etched using an inert gas mixed plasma to form an etched surface;

[0053] A platinum electrode layer is formed on the etched surface using a magnetron sputtering process;

[0054] The platinum electrode layer is heat-treated to stabilize its crystallization.

[0055] In some specific embodiments, before forming the platinum electrode layer on the substrate 400, the substrate 400 needs to be treated to ensure the surface of the substrate 400 is clean; specifically, during the surface treatment of the substrate 400, Ar (argon gas) and (Nitrogen) is mixed in a 1:1 ratio and excited to form a mixed plasma for etching the substrate 400; the etching power is 125-175W, and the etching time is 3-7 minutes; more specifically, an etching power of 150W is used, that is, the radio frequency etching power for generating and maintaining the mixed plasma is 150W, thereby forming Ar / Mixed plasma; utilizing Ar / The surface of the substrate 400 is micro-etched by the mixed plasma for a time of 3-7 min, preferably 5 min, thereby removing contaminants or oxides from the surface of the substrate 400 and forming a low-roughness etched surface. This improves the orientation, density and adhesion of the subsequent platinum atom (111) crystal plane to the substrate 400, and prevents the platinum electrode layer from cracking.

[0056] In some specific embodiments, a platinum electrode layer is formed on the etched surface using magnetron sputtering. Specifically, in the magnetron sputtering process, a 99.999% high-purity platinum target is selected, with a target-to-substrate distance of 10 cm and a working gas pressure of 0.5 Pa. More specifically, pulsed radio frequency sputtering is performed using a 99.999% pure platinum target in a mixed atmosphere of Ar:He = 3:1 and a working gas pressure of 0.5 Pa. The peak power of the pulsed radio frequency sputtering is 140 W, the pulse width is 20 ms, and the pulse frequency is 50 Hz. Simultaneously, the temperature of the substrate 400 is controlled to be maintained between 190°C and 210°C, preferably at 200°C. That is, by synergistically suppressing particles and improving plasma fluidity through high-purity gas and pulsed mode, a dense, stress-free platinum film is obtained.

[0057] In some more specific embodiments, after the platinum electrode layer is formed, the temperature of the reaction chamber 100 is raised to 300°C and held for 10 minutes to stabilize the Pt(111) crystal. Here, Pt(111) represents the preferred orientation of the platinum crystal along the (111) crystal plane, which is well known to those skilled in the art and will not be described in detail here.

[0058] In some embodiments, a precursor gas is introduced into the reaction chamber 100 to provide aluminum and scandium atoms to the platinum electrode layer, including...

[0059] Using an inert gas as the carrier gas, (Trimethylaluminum) gas is pulsed into reaction chamber 100 to provide aluminum atoms to the platinum electrode layer;

[0060] Using an inert gas as the carrier gas, A gas pulse is introduced into reaction chamber 100 to provide scandium atoms to the platinum electrode layer.

[0061] In some specific embodiments, the precursor gas introduced into the reaction chamber 100 needs to provide aluminum and scandium atoms for the platinum electrode layer. Specifically, trimethylaluminum gas is introduced into the reaction chamber 100 to provide aluminum atoms for the platinum electrode layer. The gas provides scandium atoms to the platinum electrode layer.

[0062] In some more specific embodiments, the gas cylinder at the end of the first pipeline 210 stores trimethylaluminum gas, and the inert gas in the carrier gas pipeline 230 can transfer the trimethylaluminum gas stored in the gas cylinder to the reaction chamber 100, thereby providing aluminum atoms for the platinum electrode layer; the gas cylinder at the end of the second pipeline 220 stores... The inert gas in carrier gas line 230 can contain the gas stored in the gas cylinder. The gas is transferred into reaction chamber 100, thereby providing scandium atoms to the platinum electrode layer. More specifically, the inert gas can be argon or nitrogen, which is not limited here. The introduced trimethylaluminum gas and The gases are free of impurities such as chlorine, oxygen, sulfur, and fluorine, ensuring that the prepared films have high purity.

[0063] In some embodiments, the precursor gas is repeatedly circulated to deposit a thin film of the target thickness on the surface of the platinum electrode layer, including...

[0064] Trimethylaluminum gas is circulated through the gas to form an AlN (aluminum nitride) layer;

[0065] Circulation input The gas forms a Scandium Nitride (ScN) layer;

[0066] Repeatedly introducing trimethylaluminum gas and introducing The gas is processed to form a thin film of the target thickness.

[0067] In some specific embodiments, a composite deposition mode is achieved by superimposing independent cycling units of AlN and ScN. Simultaneously, by adjusting the repetition ratio of the two single cycling units, precise control of the Sc (scandium) content ratio can be achieved, thereby realizing the preparation of AlScN thin films.

[0068] In some embodiments, trimethylaluminum gas is circulated to form an aluminum nitride layer, including...

[0069] Trimethylaluminum gas is introduced into the reaction chamber in 100 pulses; the pulse duration is 0.1-0.5 s.

[0070] Use carrier gas for purging; the carrier gas flow rate is 500-700 sccm, and the purging time is 1-5 seconds.

[0071] Ammonia gas is pulsed into the reaction chamber at a rate of 100 volts; pulse duration is 1-3 seconds.

[0072] The aluminum nitride lattice unit layer is formed by purging again with carrier gas; the flow rate of the carrier gas is 500-700 sccm and the purging time is 55-65s.

[0073] Repeat the above steps until the aluminum nitride lattice unit layers are stacked to a set thickness to form an aluminum nitride layer.

[0074] In some specific embodiments, the purpose of pulsedly introducing trimethylaluminum gas into the reaction chamber 100 is to allow the –NH (amino) sites on the surface of the platinum electrode layer to react with the trimethylaluminum gas to generate –N– Monolayer. Purging with a carrier gas removes unadsorbed byproducts, preventing particle formation from subsequent gas-phase reaction with ammonia. After purging, ammonia is introduced to react with the surface. Ligand exchange occurs, releasing reaction residues and leaving –Al–NH– bonds, completing an Al–N unit cell. The system is then purged again with carrier gas to remove the reaction residues and prevent particle deposition. The purging time is maintained at 55-65 seconds to ensure no cross-contamination occurs during the cycle.

[0075] In some more specific embodiments, the process is repeated 10 times.

[0076] In some embodiments, cyclic flow is used. Gases form a scandium nitride layer, including...

[0077] A 100-pulse pulse is introduced into the reaction chamber. Gas; Pulse duration 1-3s;

[0078] Use carrier gas for purging; the carrier gas flow rate is 500-700 sccm, and the purging time is 5-10 seconds.

[0079] Ammonia gas is pulsed into the reaction chamber at a rate of 100 volts; pulse duration is 1-3 seconds.

[0080] The scandium nitride lattice unit layer is formed by purging again with carrier gas; the flow rate of the carrier gas is 500-700 sccm and the purging time is 15-30s.

[0081] Repeat the above steps until the scandium nitride lattice unit layer is stacked to a set thickness to form a scandium nitride layer.

[0082] In some specific embodiments, pulses continue to be introduced into the reaction chamber 100. Gas, thus allowing the surface – NH and Gas reaction, producing Monolayer. Among them, For the current platinum electrode surface –NH– and One The ligand undergoes displacement, releasing an H- Molecules, thus leaving i The ligand is N,N′-diisopropylformamidinyl. Then, a carrier gas is used for purging to remove unadsorbed Sc source and... The ligands are removed to prevent interference with subsequent reactions with ammonia. After purging, ammonia is introduced, and the ammonia reacts with the surface... Ligand exchange occurs, eliminating The ligands retain –Sc–NH– bonds while releasing reaction residues, completing the Sc–N lattice unit. The mixture is then purged again with a carrier gas to remove the reaction residues.

[0083] In some more specific embodiments, the process is repeated 40 times; this, combined with the aforementioned process for forming an aluminum nitride layer, constitutes an “AlN–ScN supercycle”, ensuring that Sc:Al≈1:3, thereby forming a single-layer AlScN thin film on the wafer surface.

[0084] In some more specific embodiments, the "AlN–ScN supercycle" process is performed 40 times, and the AlScN film in this process is 30 nm thick with Sc:Al ≈ 1:3.

[0085] In some embodiments, the precursor gas is repeatedly circulated to deposit a thin film of the target thickness on the surface of the platinum electrode layer, and the process further includes:

[0086] Keep the temperature of the reaction chamber 100 constant, and introduce inert gas into the reaction chamber 100 for 10-50 minutes.

[0087] The temperature inside the reaction chamber 100 is reduced to room temperature at the set cooling rate, and the substrate 400 is removed.

[0088] In some specific embodiments, after the above deposition process is completed, it is necessary to keep the temperature inside the reaction chamber 100 constant and continue to introduce carrier gas for 10-50 minutes, preferably 30-40 minutes. The specific time is not limited here. Different carrier gas durations are selected according to different needs during the reaction process. Maintaining the temperature of the reaction chamber 100 and continuing to introduce carrier gas can remove residual reactants. That is, immediately after deposition, a large amount of residual reactants and organic by-products are still adsorbed in the chamber wall and exhaust pipe. By introducing carrier gas, these residues can be quickly carried out to prevent secondary reactions with the film surface during the cooling stage. At the same time, continuous purging while maintaining the temperature is equivalent to annealing in a non-reactive atmosphere, which can give the surface Al / Sc atoms additional diffusion time to fill vacancies.

[0089] In some specific embodiments, the chamber temperature is reduced to room temperature at a cooling rate of 5-8°C / min to reduce the possibility of film cracking.

[0090] In some embodiments, trimethylaluminum gas is circulated to form an aluminum nitride layer. After this process, the control valve of the reaction chamber is closed, and the pressure and temperature of the reaction chamber are kept constant for 1-3 minutes to allow atomic diffusion on the surface of the aluminum nitride layer.

[0091] Circulation input After the gas forms a scandium nitride layer, the control valve of the reaction chamber is closed, and the pressure and temperature of the reaction chamber are kept constant for 1-3 minutes to allow the atoms on the surface of the scandium nitride layer to diffuse.

[0092] In some specific embodiments, closing the control valve of the reaction chamber and keeping the pressure and temperature of the reaction chamber constant can be equivalent to annealing in a non-reactive atmosphere, which can give the surface Al / Sc atoms extra diffusion time to fill vacancies.

[0093] Reference Figure 3 and Figure 4 For ternary nitrides like AlScN, impurity control in the precursor is particularly important. For example, excessive oxygen impurities can affect the oxygen defect content in the film. Similarly, impurities such as chlorine, oxygen, sulfur, and fluorine can also affect film quality. This invention uses trimethylaluminum and... (tris(N,N'-diisopropylmethylamidinyl)scandiumIII) as a precursor largely avoids the residue of other impurities. Its specific chemical structure is shown below. Figure 3 as well as Figure 4 As shown.

[0094] Reference Figures 5-8 By adjusting the number of single cycles of AlN, an AlN film with a target thickness of 30 nm can be obtained (average film thickness of 30.14 nm and uniformity of 0.61% under 49-point thickness statistics). By adjusting the single-cycle ratio and supercycle number of AlN and ScN, an AlScN film with a target thickness of 30 nm can be obtained (average film thickness of 30.31 nm and uniformity of 1.34% under 49-point thickness statistics). Meanwhile, the average n-value of AlScN is 1.96, slightly lower than that of AlN (2.06), indicating that Sc doping has a certain impact on the overall film thickness uniformity and density. However, a film uniformity of approximately 1% is sufficient to demonstrate the superiority of this process for film growth.

[0095] Reference Figure 9After obtaining the AlScN film of the target thickness, the present invention performed XPS elemental analysis. Characteristic peaks of Al2p and N1s were found at approximately 80 eV and approximately 400 eV, respectively, confirming the presence of the AlN film. The presence of a Sc2p characteristic peak at approximately 400 eV, along with satellite peaks of Sc2s, Sc3s, and Sc3p at approximately 500 eV, 60 eV, and 30 eV, and multiple Auger peaks (ScLM1, ScLM2, ScLM3) in the 1100 eV–1200 eV range, confirms the successful incorporation of Sc into the AlN host film, demonstrating the successful preparation of AlScN films via the “AlN-ScN supercycling” process.

[0096] Reference Figure 10 , Figure 10 For AlN thin films and X-ray diffraction (XRD) pattern of a thin film; the horizontal axis represents the diffraction angle, which is twice the angle between the incident X-ray and the diffracted X-ray. XRD scans typically use the 2θ angle as the horizontal axis because it is directly related to the interplanar spacing (d-value) of the crystal. Using Bragg's law (nλ = 2dsinθ), the 2θ angle can be converted to the interplanar spacing d, thus allowing analysis of the material's crystal structure; the vertical axis represents the diffraction intensity, which is the intensity of the diffracted X-rays received by the detector. Diffraction intensity reflects the diffraction capability of the corresponding crystal plane in the crystal and is related to factors such as crystallinity, grain size, and preferred orientation. In the XRD pattern, the position (2θ angle) and relative intensity of the diffraction peaks are key information for analyzing the material's crystal structure. Figure 10 The x-axis represents the range of 20° to 40° within the 2θ scanning range, while the y-axis shows the diffraction intensity detected within this angular range. For pure AlN films (black curve), a distinct diffraction peak appears near 2θ≈35.7°, corresponding to the (002) crystal plane orientation of wurtzite AlN; while The thin film (red curve) also showed a (002) crystal plane diffraction peak at 2θ≈35.9°, and the intensity of the diffraction peak was relatively higher, indicating that Sc element not only successfully achieved doping, but also exhibited a crystalline state similar to AlN; at the same time, The (002) diffraction peak in the thin film showed a shift of 0.4° due to Sc doping, which not only altered the lattice structure of AlN (because...). Ionic radius greater than This also leads to lattice expansion.

[0097] Reference Figure 11 , Figure 11The piezoelectric force microscopy (PFM) phase map of the AlScN thin film shows the phase signal distribution within a 2 μm × 2 μm area. The color bar corresponds to the phase value (range -115.5° to 208.5°). The dense granular texture within the area represents the domain distribution in the AlScN film. The overall signal is uniform and there are no obvious large domain regions, indicating that the film's domain structure exhibits a fine multi-domain characteristic. Combined with the continuity of color changes, it can be determined that the AlScN film has good uniformity, which is consistent with the high crystallinity shown by previous XRD. This figure shows that the film has a responsive phase signal, providing strong microscopic support for further exploration of its ferroelectric effect.

[0098] The implementation principle of the AlScN thin film preparation method and system in this application embodiment is as follows: AlScN thin films are prepared by alternating deposition of aluminum nitride and scandium nitride layers to form a supercycle. The thickness and composition of the thin film are controlled using a precursor free of impurities such as chlorine, oxygen, sulfur, and fluorine. After each layer is deposited, the inlet valve is closed for in-situ micro-annealing, repairing defects and releasing stress layer by layer. This cycle forms an AlScN thin film of the target thickness, resulting in a crystalline aluminum nitride / scandium thin film with uniform thickness, precise composition, and extremely low impurities. Simultaneously, the precursor gas does not introduce impurities, reducing the complexity of the process. Furthermore, no subsequent high-temperature annealing is required to achieve crystalline properties, thus realizing the low-temperature growth of crystalline AlScN thin films.

[0099] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for preparing an AlScN thin film, characterized in that, Includes the following steps: Provide a base; The substrate is etched using an inert gas mixed with plasma to form an etched surface; A platinum electrode layer is formed on the etched surface by magnetron sputtering. The high lattice matching between the (111) crystal plane of the platinum electrode on the sapphire substrate and the (002) crystal plane of AlScN wurtzite is utilized to induce the AlScN film to spontaneously form sharp wurtzite (002) diffraction peaks through crystal form induction. The platinum electrode layer is subjected to heat treatment to stabilize its crystallization. The substrate is placed in the reaction chamber, and the reaction chamber is pretreated to make the pressure in the reaction chamber a predetermined value and the temperature 340℃-400℃. Using an inert gas as a carrier gas, trimethylaluminum gas is pulsed into the reaction chamber to provide aluminum atoms to the platinum electrode layer, forming an aluminum nitride layer. The control valve of the reaction chamber is closed, and the pressure and temperature of the reaction chamber are kept constant for 1-3 minutes to allow the atoms on the surface of the aluminum nitride layer to diffuse and repair lattice defects layer by layer and release deposition stress. Trimethylaluminum gas is circulated in to form an aluminum nitride layer. Using an inert gas as the carrier gas, A gas pulse is introduced into the reaction chamber to provide scandium atoms to the platinum electrode layer, forming a scandium nitride layer. The control valve of the reaction chamber is then closed, and the pressure and temperature of the reaction chamber are maintained constant for 1-3 minutes to allow atomic diffusion on the surface of the scandium nitride layer and to repair lattice defects layer by layer, releasing deposition stress. The gas is then circulated through the reaction chamber. The gas forms a scandium nitride layer; Repeatedly introducing trimethylaluminum gas and introducing The gas is processed to form a thin film of the target thickness.

2. The preparation method according to claim 1, characterized in that, The etching of the substrate using an inert gas mixed plasma to form an etched surface includes, Argon and nitrogen are mixed in a 1:1 ratio and excited to form a mixed plasma for etching the substrate; The etching power is 125-175W, and the etching time is 3-7 minutes.

3. The preparation method according to claim 1, characterized in that, The circulating introduction of trimethylaluminum gas forms an aluminum nitride layer, including, Trimethylaluminum gas is pulsed into the reaction chamber; the pulse duration is 0.1-0.5 s. Use carrier gas for purging; the carrier gas flow rate is 500-700 sccm, and the purging time is 1-5 seconds. Ammonia gas is pulsed into the reaction chamber; the pulse duration is 1-3 seconds. The aluminum nitride lattice unit layer is formed by purging again with carrier gas; the flow rate of the carrier gas is 500-700 sccm and the purging time is 55-65s. Repeat the above steps until the aluminum nitride lattice unit layer is stacked to a set thickness to form the aluminum nitride layer.

4. The preparation method according to claim 1, characterized in that, The cyclic input Gases form a scandium nitride layer, including... Pulse flow into the reaction chamber Gas; Pulse duration 1-3s; Use carrier gas for purging; the carrier gas flow rate is 500-700 sccm, and the purging time is 5-10 seconds. Ammonia gas is pulsed into the reaction chamber; the pulse duration is 1-3 seconds. The scandium nitride lattice unit layer is formed by purging again with carrier gas; the flow rate of the carrier gas is 500-700 sccm and the purging time is 15-30s. Repeat the above steps until the scandium nitride lattice unit layer is stacked to a set thickness to form the scandium nitride layer.

5. The preparation method according to claim 1, characterized in that, It also includes, Keep the temperature of the reaction chamber constant and introduce inert gas into the reaction chamber for 10-50 minutes. The temperature inside the reaction chamber is reduced to room temperature at a set cooling rate, and the substrate is then removed.

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