Al1-xScxN film and preparation method and application thereof

Abstract

The invention discloses an Al < 1-x > Sc < x > N film and a preparation method and application thereof, and belongs to the technical field of novel semiconductor materials. The preparation method of the Al1-xScxN thin film comprises the following steps: S1, preparing sol by taking a mixed organic solution of aluminum salt and scandium salt as a raw material; s2, coating the sol on a substrate and carrying out heat treatment to obtain an intermediate film; and S3, calcining the intermediate film in an atmosphere containing ammonia gas. The preparation method provided by the invention is simpler to operate, lower in instrument requirement and cheaper in raw materials, but the performance of the prepared Al1-xScxN thin film is equivalent to or even better than that of a thin film prepared by traditional MOCVD (Metal Organic Chemical Vapor Deposition). The invention further provides the Al < 1-x > ScxN thin film prepared by the preparation method and application of the Al < 1-x > ScxN thin film.

Description

Technical Field

[0001] This invention relates to the field of novel semiconductor materials technology, and in particular to an Al 1-x Sc x N thin films, their preparation methods, and applications. Background Technology

[0002] With the advent of the Internet of Everything era, the rapid development of AI large-scale models and AI intelligent agents, the speed and volume of data acquisition required for human production and life are constantly increasing. High-frequency detection, wireless transmission of big data, and the development of 6G all require detectors and filters that can operate at high frequencies. 1-x Sc x Nitrogen (N) possesses higher piezoelectric coefficients, higher sound velocity, higher electromechanical coupling coefficients, and lower dielectric loss, and is compatible with CMOS processes, making it an ideal material for piezoelectric layers in high-frequency detectors and FBAR (film bulk acoustic resonator) filters. In big data computing and storage, traditional von Neumann computing architectures, when handling parallel computing, experience significant data transfer between computing and storage units, leading to high power consumption and signal delay. Ferroelectric Al 1-x Sc x N possesses significant potential for applications such as large remanent polarization, no size effect, low dielectric constant, stable ferroelectricity, CMOS compatibility, gate-oriented 3D stacking for ferroelectric devices, low-power storage, and neuromorphic computing. Because of these advantages, Al... 1-x Sc x Nitrogen (N) has become a high-tech material of strategic significance.

[0003] About Al 1-x Sc x Currently, the preparation methods for N thin film materials include molecular beam epitaxy (MBE), magnetron sputtering (MS), metal-organic chemical vapor deposition (MOCVD), pulsed laser deposition (PLD), physical vapor deposition (PVD), and atomic layer deposition (ALD).

[0004] Thin films with a 20% scandium concentration have begun to enter the commercialization stage, while aluminum nitride thin films with higher scandium contents (collectively referred to as high scandium content) are still in the research and development stage. Although Al grown by MOCVD... 1-x Sc x While N films generally exhibit good quality, the following limitations remain in the preparation of high scandium-content films: Traditional processes for preparing high scandium-content aluminum nitride films are prone to uneven scandium distribution, and Al formation on the target surface can also lead to problems. 1-x Sc x N leads to problems such as target poisoning; furthermore, the preparation of Al using traditional techniques... 1-x Scx N-films are expensive. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes an Al... 1-x Sc x The preparation method of N thin films, and the traditional Al thin film preparation method. 1-x Sc x Compared to other methods for preparing Al thin films, this method is simpler to operate, requires less equipment, and uses cheaper raw materials, but the resulting Al... 1-x Sc x The performance of N thin films is comparable to that of thin films prepared by conventional MOCVD.

[0006] The present invention also provides Al prepared by the above method. 1-x Sc x N thin film.

[0007] The present invention also provides the above-mentioned Al 1-x Sc x Applications of N thin films.

[0008] According to an embodiment of the first aspect of the present invention, an Al is provided. 1-x Sc x A method for preparing N thin films, the method comprising the following steps:

[0009] S1. A sol was prepared using a mixed organic solution of aluminum salt and scandium salt as raw material;

[0010] S2. The sol is coated onto a substrate and heat-treated to obtain an intermediate film;

[0011] S3. The intermediate film is calcined in an ammonia-containing atmosphere.

[0012] The mechanism of the preparation method is as follows:

[0013] After sol-coating and heat treatment, Sc-doped alumina thin films are obtained, where the Sc ratio determines the final Al content. 1-x Sc x The doping concentration of Sc in the N thin film; the uniformity of Sc dispersion and the thickness uniformity of the intermediate film, etc., affect the obtained Al 1-x Sc x Performance of N thin films.

[0014] Step S3 is actually a process of nitriding the intermediate film using CVD, specifically replacing the O with N.

[0015] Overall, the preparation method is a combination of sol-gel method and CVD method.

[0016] The preparation method according to embodiments of the present invention has at least the following beneficial effects:

[0017] The preparation method provided by this invention is suitable for high scandium content, high quality, and large-area Al. 1-x Sc x The fabrication of N-type thin films is simple, requires minimal equipment, and has low production costs. Furthermore, by combining it with plasma-enhanced chemical vapor deposition (PECVD), it holds promise for compatibility with complementary metal-oxide-semiconductor (CMOS) processes, providing a new method for developing independently controllable piezoelectric and ferroelectric thin films and laying a solid foundation for the development of related devices. Specifically:

[0018] In steps S1-S2 of this invention, the sol-gel method facilitates the introduction of high scandium content and uniform doping. Combined with the chemical vapor deposition process, the chemical reaction between the intermediate film and ammonia at high temperatures further enhances crystallinity and reduces crystal defects, resulting in a high-quality, denser, and lower-stress Al crystal structure. 1-x Sc x N thin film.

[0019] In summary, the preparation method provided by this invention combines the sol-gel method with CVD technology, solving the current difficulty in preparing high scandium content and high-quality Al. 1-x Sc x The challenge of N thin films is to prepare high-quality films with scandium content higher than 30% or even higher than 43%, and to achieve low cost and large-scale mass production.

[0020] According to some embodiments of the present invention, in step S1, the molar ratio of Sc to the sum of Al and Sc in the aluminum salt and scandium salt is ≥25%. Specifically, it can be about 30%, 35%, 40%, or about 45%.

[0021] According to some embodiments of the present invention, in step S1, the aluminum salt includes at least one of aluminum nitrate or its hydrate, aluminum isopropoxide and aluminum chloride, specifically aluminum nitrate nonahydrate.

[0022] According to some embodiments of the present invention, in step S1, the scandium salt includes at least one of scandium nitrate or its hydrate, or scandium chloride. For example, it may specifically be scandium nitrate hydrate.

[0023] According to some embodiments of the present invention, in step S1, the solvent of the mixed organic solution includes at least one of ethylene glycol methyl ether (CAS: 109-86-4), isopropanol, and ethanol.

[0024] According to some embodiments of the present invention, in step S1, the concentration of metal ions in the mixed organic solution is 0.25 to 0.35 mol / L; specifically, it can be about 0.3 mol / L.

[0025] According to some embodiments of the present invention, step S1 further includes a stabilizer. The stabilizer includes at least one selected from diethanolamine, triethanolamine, glucose, and citric acid. Therefore, the heat treatment in step S2 can also have a certain carbothermic reduction effect, and the resulting Al... 1-x Sc x N-films have better quality in terms of flatness and other aspects.

[0026] According to some embodiments of the present invention, in step S1, the method for preparing the sol includes sequential stirring and settling. The stirring time is 10–15 hours; specifically, it can be about 12 hours or about 14 hours; the settling time is ≥2 days; for example, it can be about 3 days. This allows the components in the mixed organic solution to fully react and form a gel.

[0027] According to some embodiments of the present invention, in step S2, the substrate includes at least one of monocrystalline silicon, silicon carbide, molybdenum, platinum, fluorinated phlogopite, and sapphire.

[0028] According to some embodiments of the present invention, in step S2, the substrate is monocrystalline silicon. In actual use, the Al... 1-x Sc x N thin films are deposited on the Si(100) or Si(111) surfaces of single-crystal silicon.

[0029] According to some embodiments of the present invention, step S1 further includes pretreatment of the substrate. The pretreatment includes sequential cleaning, drying, and atmospheric plasma treatment. This removes surface impurities and improves the hydrophilicity of the substrate. The cleaning includes at least one of acetone ultrasonic cleaning and ethanol ultrasonic cleaning; the duration of a single ultrasonic cleaning is 10–30 min; specifically, it can be about 20 min; more specifically, the cleaning includes sequential acetone ultrasonic cleaning and ethanol ultrasonic cleaning (in actual production, the appropriate cleaning method can be selected according to the cleanliness of the available substrate material). The drying temperature is 300–400°C; specifically, it can be about 350°C; the drying duration is 1–30 min; specifically, it can be about 5 min or about 10 min; in actual production, this duration is not strictly limited, as long as drying is achieved. The atmospheric plasma treatment is performed 1–3 times; specifically, it can be 2 times.

[0030] By selecting a suitable substrate and a suitable substrate pretreatment method, the performance of the Al was significantly improved. 1-x Sc x The adhesion strength between the N film and the substrate.

[0031] According to some embodiments of the present invention, in step S2, the coating method includes spin coating. The spin coater used for spin coating operates at a speed of 4000–5000 rpm, specifically approximately 4500 rpm. The acceleration of the spin coater is 500–3000 rad / s. 2 For example, it could be approximately 600 rad / s. 2 1000rad / s 2 1500rad / s 2 2000rad / s 2 or approximately 2500 rad / s 2 .

[0032] Therefore, by controlling the above parameters, the thickness of the resulting intermediate film can be controlled to a certain extent. Specifically, the faster the rotation speed and the faster the acceleration, the thinner the intermediate film.

[0033] According to some embodiments of the present invention, in step S2, after coating, a preheating treatment is further included. This allows the wet film to be dried into a dry film. The preheating treatment can be a single preheating treatment or a double preheating treatment. The single preheating treatment is performed at a temperature of 150–200°C; specifically, about 180°C; for a duration of 5–15 minutes; specifically, about 10 minutes. The double preheating treatment includes first preheating at 150–200°C for 1–5 minutes, followed by preheating at 350–450°C for 3–8 minutes. Compared to a single preheating treatment, the solvent evaporates faster in a double preheating treatment, which can improve production efficiency. However, due to the excessively rapid solvent evaporation, the surface smoothness and overall morphology of the resulting intermediate film may be slightly reduced.

[0034] According to some embodiments of the present invention, in step S2, the steps prior to the heat treatment are repeated. This allows for the acquisition of the corresponding film thickness. The repetition is performed more than once, for example, four or five times.

[0035] According to some embodiments of the present invention, in step S2, the atmosphere of the heat treatment is one of air, nitrogen, argon, or an argon-hydrogen mixture.

[0036] According to some embodiments of the present invention, in step S2, the temperature of the heat treatment is 700–950°C. Specifically, it can be about 750°C, 800°C, 850°C, 900°C, or about 950°C. The heat treatment temperature is lower than the temperature at which alumina transforms to the α-phase, resulting in an alumina film with high active scandium content (intermediate film); the phase of the obtained intermediate film is γ-Al₂O₃, δ-Al₂O₃, or θ-Al₂O₃.

[0037] According to some embodiments of the present invention, in step S2, the heat treatment duration is 10–120 min. Specifically, it can be approximately 20 min, 30 min, 60 min, or approximately 90 min. In actual production, the equipment used for the heat treatment includes rapid annealing furnaces and CVD equipment (e.g., tube furnaces); and if the rapid annealing furnace is used, the required heat treatment duration is 10–30 min; if other equipment is used, the heat treatment duration is 30–120 min.

[0038] More specifically, the heat treatment can be carried out in an air atmosphere by holding at 800°C for 10 minutes in a rapid annealing furnace.

[0039] Alternatively, the heat treatment may be performed in an inert gas atmosphere, holding at 700°C for 120 minutes in a tube furnace.

[0040] Alternatively, the heat treatment can be performed by holding at 850°C for 2 hours in an air atmosphere.

[0041] The inert gas includes at least one of nitrogen and argon.

[0042] In step S2, the atmosphere flow rate is not limited in the heat treatment. If it is an air atmosphere, it can be calcined directly in an open environment. If it is a specific atmosphere, gas flow is sufficient, for example, it can be ≥50 sccm.

[0043] According to some embodiments of the present invention, in step S2, the heating rate of the heat treatment is 5 to 25 °C / min. For example, it can be about 6 °C / min, 10 °C / min, 15 °C / min, or about 20 °C / min.

[0044] According to some embodiments of the present invention, in step S2, if the heat treatment requires an external gas as a protective gas, the flow rate of the external gas is 50–300 sccm. Specifically, it can be approximately 100 sccm, 150 sccm, 200 sccm, or approximately 250 sccm.

[0045] According to some embodiments of the present invention, step S2 further includes subjecting the obtained intermediate film to atmospheric plasma treatment after the heat treatment. This activates the intermediate film and alters its surface bonding (forming aluminum-nitrogen-oxygen dangling bonds), making it more favorable for subsequent nitriding treatment. In combination with the conditions of the heat treatment, an intermediate film in an oxidized state more conducive to nitriding is obtained. This further facilitates the reaction of the intermediate film with active ammonia gas produced by the catalytic decomposition of nitrogen source by the ammonia decomposition catalyst, or with active hydrogen and active nitrogen elements produced by the decomposition of reactive ammonia gas, achieving a good nitrogen-oxygen replacement effect.

[0046] According to some embodiments of the present invention, in step S3, the ammonia gas is sourced from externally introduced ammonia gas or decomposition products of a nitrogen source. Directly using ammonia gas results in higher reactivity and is simpler; compared to directly using ammonia gas, using a nitrogen source for decomposition reduces costs and avoids the safety risks of leakage.

[0047] According to some embodiments of the present invention, in step S3, when the ammonia gas is sourced from an externally introduced ammonia gas, the flow rate of the ammonia gas is 50–300 sccm. For example, the flow rate can be approximately 60 sccm, 100 sccm, or approximately 200 sccm. In this case, the ammonia gas serves as both a reactant and a carrier gas, and no additional carrier gas is required.

[0048] According to some embodiments of the present invention, when the ammonia gas is a decomposition product of a nitrogen source, the nitrogen source includes at least one of urea, ammonium chloride, melamine, and ammonium carbonate.

[0049] According to some embodiments of the present invention, the decomposition process of the nitrogen source is achieved under the action of an ammonia decomposition catalyst; the ammonia decomposition catalyst is at least one selected from tungsten mesh, iron-based materials, nickel-based materials, and carbon-ruthenium-based materials. The catalyst is used to regulate the decomposition of the nitrogen source, but the nitrogen source will still decompose into ammonia even without the addition of a catalyst; in actual production, whether or not to add a catalyst can be selected as needed.

[0050] In the above-described case, the intermediate film is positioned at the center temperature zone of the furnace tube in the CVD equipment; and...

[0051] A nitrogen source (hereinafter referred to as the first nitrogen source) is installed in the furnace tube of the CVD equipment near the air inlet;

[0052] Alternatively, in the furnace tube of the CVD equipment, a second nitrogen source is disposed between the first nitrogen source and the intermediate film, and the second nitrogen source and the intermediate film are adjacent to each other;

[0053] Alternatively, a third nitrogen source may be provided between the first nitrogen source and the second nitrogen source in the furnace tube of the CVD equipment.

[0054] Alternatively, the ammonia decomposition catalyst may be disposed between the intermediate film and the nearest nitrogen source. That is, if the ammonia decomposition catalyst is disposed, it will be in essentially contact with the ceramic boat containing the intermediate film, and the entire material will be located in the intermediate temperature zone.

[0055] According to some embodiments of the present invention, in step S3, before calcination, the reaction equipment needs to be replaced with the carrier gas (or ammonia) to avoid impurities such as oxygen affecting the subsequent reaction.

[0056] According to some embodiments of the present invention, in step S3, the calcination temperature is 600–1350°C. Specifically, it can be approximately 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1200°C, or approximately 1300°C. By controlling the nitriding temperature of the calcination, the temperature at which the α-phase transforms into AlScN can be reached, or the nitriding temperature can be controlled below the α-phase transformation temperature, but the nitriding treatment time is extended, thus obtaining nanoscale thickness active scandium-doped alumina films (Al0.05) with different crystal morphologies. 1-x Sc x N-thin film).

[0057] Furthermore, the nitriding of alumina to form aluminum nitride typically requires a liquid phase environment or the presence of a catalyst / nitriding aid. This invention controls the phase of the resulting intermediate film and its nitridability by controlling the heat treatment temperature in step S2. Combined with the calcination treatment in step S3, it achieves complete nitriding without the addition of a catalyst using a solid-state method.

[0058] According to some embodiments of the present invention, in step S3, the holding time for calcination is 2 to 10 hours. For example, it can be about 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or about 9 hours.

[0059] According to some embodiments of the present invention, in step S3, the calcination is a single-stage calcination.

[0060] According to some embodiments of the present invention, in step S3, the calcination includes a first-stage calcination and a second-stage calcination performed sequentially. The first-stage calcination is performed at a temperature of 900–1000°C for a duration of 10–60 min (specifically, approximately 20 min, 30 min, or 40 min); the second-stage calcination is performed at a temperature of 1050–1150°C for a duration of 5–9 h (specifically, approximately 8 h).

[0061] According to some embodiments of the present invention, in step S3, the calcination atmosphere further includes a carrier gas, which includes at least one of nitrogen, argon, helium, krypton, xenon, neon, radon, and hydrogen.

[0062] According to some embodiments of the present invention, in step S3, the flow rate of the atmosphere is 50 to 300 sccm. For example, the flow rate may be about 60 sccm, 100 sccm, or about 200 sccm.

[0063] According to some embodiments of the present invention, in step S3, the heating rate of the calcination is 3 to 30 °C / min. Specifically, it can be about 5 °C / min, 10 °C / min, 15 °C / min, 20 °C / min, or about 25 °C / min. In actual production, a fixed CVD equipment (tube furnace) can be selected, whereby the nitrogen source and the intermediate film are heated along with the furnace; alternatively, a CVD equipment with a sliding function can be selected, whereby the intermediate film can be transferred to the central temperature zone after the calcination temperature reaches the target temperature.

[0064] According to an embodiment of the second aspect of the present invention, an Al obtained by the preparation method provided in the first aspect of the present invention is provided. 1-x Sc x N thin film, the Al 1-x Sc x In N thin films, x ≥ 0.25.

[0065] Due to the Al 1-x Sc x The N-film employs all the technical solutions of the preparation methods described in the above embodiments, and therefore possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments. Furthermore,

[0066] The Al 1-x Sc x The distribution of Sc in N thin films is more uniform, the degree of crystallinity is higher, and the piezoelectric properties are better.

[0067] According to some embodiments of the present invention, the Al 1-x Sc x In N thin films, x ≥ 0.3. For example, it can be approximately 0.35, 0.4, or approximately 0.45.

[0068] According to an embodiment of a third aspect of the present invention, a semiconductor device is provided, the semiconductor device comprising the Al described in the first aspect of the present invention. 1-x Sc x N thin film.

[0069] Because the semiconductor device employs the Al of the above embodiment 1-x Sc x The entire technical solution of N thin film therefore has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0070] According to some embodiments of the present invention, the semiconductor device includes at least one of a detector, a transducer, a filter, and a memory.

[0071] Among the detector, transducer, and filter, the Al 1-x Sc xThe N-film acts as a piezoelectric film; in the filter and memory, the Al 1-x Sc x N thin films act as ferroelectric thin films.

[0072] Unless otherwise specified, the term "about" in this invention actually means that the error is allowed to be within ±2%, for example, about 100 is actually 100 ± 2% × 100.

[0073] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0074] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0075] Figure 1 The Al obtained in Embodiment 1 of the present invention 1-x Sc x XRD pattern of N thin film.

[0076] Figure 2 The Al obtained in Embodiment 1 of the present invention 1-x Sc x Cross-sectional SEM and EDS images of N thin films.

[0077] Figure 3 The Al obtained in Embodiment 1 of the present invention 1-x Sc x Piezoelectric spectrum of N thin film.

[0078] Figure 4 The Al obtained in Example 4 of this invention 1-x Sc x XRD pattern of N thin film.

[0079] Figure 5 The Al obtained in Example 4 of this invention 1-x Sc x Piezoelectric spectrum of N thin film.

[0080] Figure 6 The Al obtained in Embodiment 1 of the present invention 1-x Sc x Atomic force microscopy images of N thin films.

[0081] Figure 7 The Al obtained in Embodiment 1 of the present invention 1-x Sc x SEM image of the surface of the N thin film.

[0082] Figure 8 The Al obtained in Example 5 of this invention1-x Sc x XRD pattern of N thin film.

[0083] Figure 9 The Al obtained in Comparative Example 1 of this invention 1-x Sc x XRD pattern of N thin film. Detailed Implementation

[0084] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0085] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0086] Example 1

[0087] This example prepared an Al 1-x Sc x N thin film, x = 30%, the specific steps are as follows:

[0088] S1. Dissolve 0.7957g of aluminum nitrate nonahydrate in 10mL of ethylene glycol methyl ether and stir until completely dissolved. Add 0.2263g of scandium nitrate hydrate and stir for 12h. Let stand for 2-3 days to obtain a sol with a concentration of 0.3mol / L. This sol is used to prepare nanoscale thickness active scandium-doped alumina thin films (intermediate films).

[0089] The Si(100) substrate was ultrasonically cleaned in alcohol for 30 min, dried at 300℃ for 3 min on a heating stage, and subjected to atmospheric plasma treatment twice to clean and improve the hydrophilicity of the substrate surface.

[0090] S2. Set the spin coater speed to 4000 r / min and the acceleration to 600 rad / s². 2The sol obtained in step S1 is spin-coated onto the Si(100) substrate obtained in step S1. It is heated at 180°C for 3 min on heating stage 1, then transferred to heating stage 2 and heated at 400°C for 5 min. After cooling to room temperature, the next layer is spin-coated. This process is repeated 5 times.

[0091] The resulting dried film was heated to 800°C for 10 min in a rapid annealing furnace at a heating rate of 20°C / min in an air atmosphere to obtain an amorphous active high scandium content alumina film (intermediate film).

[0092] S3. CVD reaction is carried out using a tube furnace.

[0093] Take two ceramic boats. Put 3g of urea (pre-ground) into the first ceramic boat, with the urea 1mm away from one side of the boat wall to prevent it from being blown away during the CVD reaction. Place the intermediate film obtained in step S2 into the second ceramic boat.

[0094] The ceramic boats are positioned such that the first ceramic boat is close to the air inlet of the tube furnace (i.e., it is basically in contact with the plug of the air inlet, and the temperature is ≥160℃ after constant temperature), with the side with the gap away from the air inlet; the second ceramic boat is placed at the center temperature (i.e., it is basically the same as the set temperature), with the largest surface of the middle film facing the direction of the carrier gas flow.

[0095] In actual production, a pipe plug is placed between the first and second ceramic boats to improve the uniformity of the distribution of ammonia gas obtained from nitrogen source decomposition in subsequent pipelines.

[0096] After the ceramic boat is placed, nitrogen is used as the carrier gas, and a mechanical pump is used to evacuate the CVD equipment tube. The vacuum level in the tube is adjusted to -0.1MPa, and nitrogen is introduced until the pressure gauge reads 0MPa. This process is repeated 3 times to remove oxygen, and then the exhaust gas treatment device is connected.

[0097] Then, the nitrogen flow rate was controlled at 50 sccm. After 10 minutes of aeration, the CVD equipment was heated to 600℃ and held at that temperature for 10 hours at a rate of 10℃ / min to produce Al. 0.7 Sc 0.3 N thin film.

[0098] Example 2

[0099] This example prepared an Al 1-x Sc x N thin film, where x = 43%; the specific steps are as follows:

[0100] S1. Dissolve 0.6479g of aluminum nitrate nonahydrate in 10mL of ethylene glycol methyl ether and stir until completely dissolved. Add 0.3244g of scandium nitrate hydrate and stir for 12h. Let stand for 2-3 days to obtain a sol with a concentration of 0.3mol / L. This sol is used to prepare nanoscale thickness active high scandium content alumina thin films (intermediate films).

[0101] A material with a thickness of 300μm and a size of 1cm 2 The Si(111) substrate was ultrasonically cleaned in acetone for 30 min, then ultrasonically cleaned in alcohol (ethanol) for 10 min, and then baked at 300°C for 3 min on a heating stage. It was then subjected to atmospheric plasma treatment twice to clean and improve the hydrophilicity of the substrate surface.

[0102] S2. Set the spin coater speed to 5000 r / min and the acceleration to 2000 rad / s². 2 The sol obtained in step S1 is spin-coated onto the Si(111) substrate. The substrate is heated at 180°C for 10 min on a heating stage 1, cooled to room temperature, and then the next layer is spin-coated. This process is repeated 5 times.

[0103] The obtained dried film was kept at 700℃ for 120 min in a tube furnace with a heating rate of 6℃ / min and a nitrogen atmosphere to obtain an amorphous active high scandium content alumina film (intermediate film).

[0104] S3. In this example, a tube furnace is used for CVD reaction.

[0105] Take three porcelain boats. Put 9g of urea into the first porcelain boat and leave a 1mm gap at one end. Put 3g of urea ground into powder into the second porcelain boat. Put the intermediate film obtained in step S2 into the third porcelain boat.

[0106] The first ceramic boat is placed near the air inlet of the tubular furnace tube, with the side with the gap away from the air inlet (when the central temperature zone of the equipment reaches 1100℃, the temperature here is ≥160℃). The third ceramic boat is placed in the central temperature zone, with the largest surface of the middle film facing the direction of the carrier gas flow. The second ceramic boat is placed between the first and third ceramic boats, and close to the third ceramic boat.

[0107] Between the second and third porcelain boats, near the third porcelain boat, a tungsten mesh is placed as a catalyst for ammonia decomposition.

[0108] In actual production, a pipe plug is placed between the first and second ceramic boats to improve the uniformity of the distribution of ammonia gas obtained from nitrogen source decomposition in subsequent pipelines.

[0109] In the above placement method, the nitrogen source in the second ceramic boat provides ammonia during the heating phase, while the nitrogen source in the first ceramic boat supplements ammonia during the constant temperature phase, thereby creating a continuous ammonia-rich atmosphere.

[0110] After the ceramic boat is properly placed, a mixture of 95% argon and 5% hydrogen is used as the carrier gas. A mechanical pump is used to evacuate the vacuum, and the vacuum level in the pipe is adjusted to -0.1 MPa. The mixture is then introduced until the pressure gauge reads 0 MPa. This process is repeated 3 times to remove oxygen by rinsing the gas. The exhaust gas treatment device is then connected.

[0111] The flow rate of the argon-hydrogen mixture was controlled at 50 sccm. After purging for 10 minutes, the CVD equipment was heated to 950℃, held for 30 minutes at a rate of 5℃ / min, and then heated to 1100℃ for 8 hours at a rate of 3℃ / min to obtain Al. 0.57 Sc 0.43 N thin film.

[0112] Example 3

[0113] This example prepared an Al 1-x Sc x N thin film, x = 30%, the specific steps are as follows:

[0114] S1. Dissolve 0.7957g of aluminum nitrate nonahydrate in 10mL of ethylene glycol methyl ether and stir until completely dissolved. Add 0.2263g of scandium nitrate hydrate and stir for 12h. Let stand for 2-3 days to obtain a sol with a concentration of 0.3mol / L. This sol is used to prepare nanoscale thickness active scandium-doped alumina thin films (intermediate films).

[0115] A material with a thickness of 300μm and a size of 1cm 2 The Si(111) substrate was ultrasonically cleaned in acetone for 30 min, then ultrasonically cleaned in alcohol for 10 min, and then baked at 300°C for 3 min on a heating stage. It was then subjected to atmospheric plasma treatment twice to clean and improve the hydrophilicity of the substrate surface.

[0116] S2. Set the spin coater speed to 5000 r / min and the acceleration to 1500 rad / s². 2 The sol obtained in step S1 is spin-coated onto the Si(111) substrate. The substrate is heated at 180°C for 10 min on a heating stage 1, cooled to room temperature, and then the next layer is spin-coated. This process is repeated 5 times.

[0117] The obtained dried film was kept at 950℃ for 120 min in a tube furnace with a heating rate of 6℃ / min and a nitrogen atmosphere to obtain an amorphous active high scandium content alumina film (intermediate film).

[0118] S3. In this example, a tube furnace is used for CVD reaction.

[0119] Take three porcelain boats. Put 6g of urea into the first porcelain boat and leave a 1mm gap at one end. Put 3g of powdered ammonium chloride into the second porcelain boat. Put the intermediate film obtained in step S2 into the third porcelain boat.

[0120] The first ceramic boat is placed near the air inlet of the tubular furnace tube, with the side with the gap away from the air inlet (when the central temperature zone of the equipment reaches constant temperature, the temperature here is ≥160℃). The third ceramic boat is placed in the central temperature zone, with the largest surface of the middle film facing the direction of the carrier gas flow. The second ceramic boat is placed between the first and third ceramic boats, and close to the third ceramic boat.

[0121] A tungsten mesh was placed between the second and third ceramic boats, near the third boat (almost in the central temperature zone), to act as a catalyst for ammonia decomposition.

[0122] In actual production, a pipe plug is placed between the first and second ceramic boats to improve the uniformity of the distribution of ammonia gas obtained from nitrogen source decomposition in subsequent pipelines.

[0123] In the above placement method, the nitrogen source in the second ceramic boat provides ammonia during the heating phase, while the nitrogen source in the first ceramic boat supplements ammonia during the constant temperature phase, thereby creating a continuous ammonia-rich atmosphere.

[0124] After the ceramic boat is properly placed, nitrogen is used as the carrier gas, and a mechanical pump is used to evacuate the vacuum. The vacuum level in the pipe is adjusted to -0.1MPa, and nitrogen is introduced until the pressure gauge reads 0MPa. This process is repeated 3 times to remove oxygen from the gas and then the exhaust gas treatment device is connected.

[0125] The nitrogen flow rate was controlled at 60 sccm (this flow rate control allows the ammonia gas obtained from the decomposition of the nitrogen source to be blown onto the surface of the intermediate film, promoting contact and reaction between the two). After 10 minutes of gas circulation, the CVD equipment was heated to 950℃ and held at that temperature for 8 hours at a rate of 5℃ / min to produce Al. 0.7 Sc 0.3 N thin film.

[0126] Example 4

[0127] This example prepared an Al 1-x Sc x The N thin film, where x = 0.3, differs from Example 3 in that:

[0128] (1) In step S2, the acceleration of the spin coater is 2500 rad / s. 2 .

[0129] (2) In step S3, the following operations are specifically adopted:

[0130] This example uses a device with a sliding function to perform the CVD reaction.

[0131] Take four porcelain boats. Put 3g of powdered urea into the first to the third porcelain boats respectively. Put the intermediate film obtained in step S2 into the fourth porcelain boat.

[0132] The first ceramic boat is placed near the air inlet of the tubular furnace tube, the fourth ceramic boat is placed in the middle position (the central temperature zone after sliding), with the largest surface of the middle film facing the direction of the carrier gas flow, the third ceramic boat is placed close to the fourth ceramic boat, and the fourth ceramic boat is padded with a graphite pad, with the middle film placed on the graphite pad; the second ceramic boat is placed between the first and third ceramic boats, and the distance between it and the fourth ceramic boat is about 25cm.

[0133] Between the third and fourth porcelain boats, near the fourth porcelain boat, a tungsten mesh is placed as a catalyst for ammonia decomposition.

[0134] In actual production, a pipe plug is placed between the first and second ceramic boats to improve the uniformity of the distribution of ammonia gas obtained from nitrogen source decomposition in subsequent pipelines.

[0135] After the ceramic boat is properly placed, argon is used as the carrier gas, and a mechanical pump is used to evacuate the vacuum. The vacuum level in the tube is adjusted to -0.1MPa, and argon is introduced until the pressure gauge reads 0MPa. This process is repeated 3 times to remove oxygen by purging the gas. The exhaust gas treatment device is then connected.

[0136] The argon flow rate was controlled at 50 sccm. After 10 minutes of gas flow, the CVD equipment was heated to 1100℃ at a rate of 10℃ / min (at this point, the central temperature zone was far from the four ceramic boats, and the temperatures in the four boats were close to room temperature). The central temperature zone was then moved to the position of the fourth ceramic boat and held at this temperature for 1 hour (at this point, a large amount of ammonia was instantly generated in the third ceramic boat, and the temperature of the second ceramic boat was ≥160℃, while the temperature of the first ceramic boat was < the temperature of ammonia catalyst decomposition). The furnace tube was then moved again to bring the central temperature zone to the position of the second ceramic boat, ensuring that the temperature of the first ceramic boat was ≥160℃ and causing the nitrogen source within it to decompose (the middle film is in the rightmost temperature zone). This process was continued for 1 hour, followed by natural cooling. The gas flow rate was increased to 200 sccm to prepare Al. 0.7 Sc 0.3 N thin film.

[0137] Example 5

[0138] This example prepared an Al 1-x Sc x N thin film, where x = 0.3; the specific steps differ from those in Example 4 in that:

[0139] (1) In step S1, the substrate is sapphire;

[0140] (1) In step S2, the dried film is kept at 700°C for 120 min in a tube furnace with a heating rate of 6°C / min and an atmosphere of air to obtain an amorphous active high scandium content alumina film (intermediate film). It is then treated twice with atmospheric plasma to activate and change the surface bonding mode of the intermediate film.

[0141] (2) In step S3, the following operations are performed:

[0142] CVD reaction was carried out using the Kejing GSL-1700X CVD equipment;

[0143] The gas inlet is located at the left end of the furnace tube of the CVD equipment, and ammonia is used as the reaction gas.

[0144] Adjust the vacuum level inside the tube to -0.1 MPa, hold for several minutes, and observe whether the vacuum count value changes to check the airtightness of the device;

[0145] After the airtightness check is completed, ammonia gas is introduced until the pressure gauge reads 0 MPa. This process is repeated 3 times to wash the gas and remove oxygen. Then, the tail gas treatment device with anti-backflow function is connected.

[0146] Ammonia gas flow rate was controlled at 50 sccm. After venting for 10 minutes, the temperature was raised to 1350℃ at a rate of 5℃ / min, and held at this temperature for 4 hours. During the cooling process, the temperature was allowed to drop naturally, and the gas flow rate was increased to 200 sccm to obtain high-quality Al. 0.7 Sc 0.3 N thin film.

[0147] Comparative Example 1

[0148] This example prepared an Al 1-x Sc x N thin film, where x = 0.3; the specific steps differ from those in Example 5 in that:

[0149] (1) In step S2, the dried film is kept at 200°C for 120 min in a tube furnace with a heating rate of 6°C / min and an air atmosphere to obtain an amorphous high scandium content alumina film (intermediate film).

[0150] Comparative XRD images, such as Figure 9 As shown, its XRD diffraction peak is a broadened peak, although it is also in Al 0.7 Sc 0.3 The position of N(100) indicates that there are fewer impurities, which means that the temperature of step S2 will affect the final form of the material. Therefore, it is necessary to control the processing temperature in S2. This temperature, combined with the nitriding temperature, can obtain the desired material while controlling the impurities as much as possible.

[0151] Test case

[0152] This example tests the Al obtained from the embodiment and the comparative example. 1-x Sc x The properties of the N thin film were tested. Specifically, XRD patterns, SEM images, EDS patterns, atomic force microscopy images, and piezoelectric patterns were measured.

[0153] The results show that when the substrate is Si(100), Al 0.7 Sc 0.3 The (100) diffraction peak of the N thin film is sharp and free of impurities, indicating good crystallinity; when the substrate is Si (111), the peak shape broadens. The XRD results obtained in Examples 1 and 4 are as follows: Figure 1 and Figure 4 As shown; in Example 4, the crystallization performance decreased slightly due to the significantly shortened calcination time, but combined with the subsequent electrical performance results, the electrical performance of the product obtained in Example 4 remained excellent. Furthermore, the Al obtained in Example 5... 0.7 Sc 0.3 The diffraction peaks of the N film are sharp and the baseline is low. Comparing Examples 1 and 5, it can be seen that using ammonia or using nitrogen source decomposition to generate ammonia can yield Al with good crystallinity. 0.7 Sc 0.3 When using a nitrogen source, the temperature of the nitriding process can be appropriately reduced, thus improving safety performance. The Al obtained in Example 5... 0.7 Sc 0.3 The XRD pattern of the N thin film is as follows: Figure 8 As shown.

[0154] Samples used for EDS and SEM testing, on substrates and Al 1-x Sc x A conductive lanthanum nickelate (LNO) film is disposed between the N films. Specifically, LNO and the gel obtained in step S1 are spin-coated sequentially, followed by heat treatment and nitriding (the latter two steps are described in Example 1). The results show that LNO and Al... 0.7 Sc 0.3 The N films exhibit distinct layers and tight bonding, and it can be observed that Al, Sc, and N elements are mainly enriched in Al. 1-x Sc x The N thin film layer exhibits a uniform elemental distribution, indicating the successful uniform doping of scandium and the successful introduction of nitrogen. Specific test results are as follows: Figure 2 As shown.

[0155] The SEM morphology test results of the samples also showed that, compared with Example 1, the other examples were better than increasing the spin coating speed and acceleration in step S2, thus resulting in higher flatness of the intermediate film and even the final product. In addition, the study of further increasing the rotation speed showed that if the rotation speed was further increased, the spin-coated film would be too thin, resulting in uncoated areas, which would affect the flatness.

[0156] Atomic force microscopy (AFM) images and surface SEM results show that the Al prepared in this invention... 1-x Sc x The N film has a smooth surface, no cracks, and is dense and uniform.

[0157] The piezoelectric test results show that the Al obtained in Examples 1 and 4 is... 1-x Sc x All N-films exhibited dish-shaped curves. The instruments used included an Oxford Instruments MFP-3D atomic force microscope, PFM, piezoelectric response force microscope, and single-point mode testing. The test voltage for Example 1 was ±40V; the test voltage for other examples was ±45V. The test results show that both samples possess good piezoelectric properties, high acoustic velocity, high electromechanical coupling coefficient, low dielectric loss, and compatibility with CMOS (silicon-based semiconductor) processes. In contrast, the Al obtained in Example 4... 1-x Sc x The N-film exhibits superior piezoelectric properties (maximum amplitude in the upper right corner; a higher value is better). Specific test results are as follows: Figure 3 and 5 As shown. Furthermore, observe... Figure 3 and Figure 5 The black curve in the figure shows that the positive and negative phase difference of the sample obtained in the embodiment of the present invention is >180 degrees, indicating domain inversion. This shows that the domains of the sample are inverted under an applied voltage, i.e., it has microscopic ferroelectric properties. Therefore, the Al provided by the present invention... 1-x Sc x N thin films are expected to be used in applications requiring high voltage coefficients and low dielectric constants, such as high-frequency detectors and filter devices; they can also be further fabricated into piezoelectric ceramics.

[0158] This example also compares the Al obtained in Example 2 and Comparative Example 1 from the above aspects. 1-x Sc x The performance of the N thin film showed that the performance of both was comparable; even the Al obtained in Example 2... 1-x Sc x The distribution of Sc is more uniform in N thin films.

[0159] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An Al 1-x Sc x The method for preparing N thin films is characterized by, The preparation method includes the following steps: S1. A sol was prepared using a mixed organic solution of aluminum salt and scandium salt as raw material; S2. The sol is coated onto a substrate and heat-treated to obtain an intermediate film; S3. The intermediate film is calcined in an ammonia-containing atmosphere.

2. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of Sc to the sum of Al and Sc in the aluminum salt and scandium salt is ≥25%.

3. The preparation method according to claim 1, characterized in that, In step S2, the temperature of the heat treatment is 700–950°C; And / or, in step S2, the duration of the heat treatment is 10 to 120 minutes.

4. The preparation method according to claim 1, characterized in that, In step S3, the ammonia gas is sourced from externally introduced ammonia gas or from the decomposition products of a nitrogen source.

5. The preparation method according to claim 4, characterized in that, When the ammonia gas is a decomposition product of a nitrogen source; the nitrogen source includes at least one of urea, ammonium chloride, melamine, and ammonium carbonate; And / or, the decomposition process of the nitrogen source is achieved under the action of an ammonia decomposition catalyst; the ammonia decomposition catalyst is at least one of tungsten mesh, iron-based material, nickel-based material and carbon-ruthenium-based material.

6. The preparation method according to claim 1, characterized in that, In step S3, the calcination temperature is 600–1350°C; And / or, in step S3, the calcination holding time is 2 to 10 hours.

7. The preparation method according to claim 1, characterized in that, In step S3, the calcination atmosphere further includes a carrier gas, which includes at least one of nitrogen, argon, helium, krypton, xenon, neon, radon, and hydrogen. And / or, in step S3, the heating rate of the calcination is 3 to 30 °C / min.

8. An Al prepared by the method according to any one of claims 1 to 7 1-x Sc x N thin film, characterized in that, The Al 1-x Sc x In N thin films, x ≥ 0.

25.

9. A semiconductor device, characterized in that, The semiconductor device includes the Al as described in claim 8 or 9. 1-x Sc x N thin film.

10. The semiconductor device according to claim 9, characterized in that, The semiconductor device includes at least one of a detector, a transducer, a filter, and a memory.

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