Gallium oxide thin film based on MPCVD process and preparation method thereof

Abstract

The invention provides a gallium oxide thin film based on an MPCVD process and a preparation method thereof, and belongs to the field of semiconductors. The method comprises the following steps: introducing a gallium source, an oxygen source and growth gas into a reaction cavity by adopting an MPCVD process, and epitaxially obtaining the gallium oxide thin film in the reaction cavity. The technical parameter formula is obtained by adjusting the technical parameters, so that the MPCVD process can be applied to preparation of the gallium oxide thin film, and the crystallization quality, compactness, grain size and growth efficiency of the prepared gallium oxide thin film are improved by utilizing the characteristics of the MPCVD process.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a gallium oxide thin film based on an MPCVD process and a preparation method thereof. Background Art

[0002] Gallium oxide belongs to the third generation of semiconductor materials. Compared with SiC, GaN and ZnO, it has a larger bandgap width, so it is called an ultra-wide bandgap semiconductor material. The bandgap width of gallium oxide can reach 4.9eV, making it an ideal material for preparing solar-blind ultraviolet detectors. It has a high breakdown field strength (8MV / cm 2 ) enables gallium oxide-based power electronic devices to have higher breakdown voltage, lower on-resistance, lower energy consumption, and higher energy utilization. Therefore, gallium oxide has great application prospects and research significance in power electronic devices and solar-blind ultraviolet detection.

[0003] Currently, there are many methods for preparing gallium oxide film materials, including radio frequency magnetron sputtering (RF-MS), pulsed laser deposition (PLD), electron beam evaporation (EBV), molecular beam epitaxy (MBE), and metal organic chemical vapor deposition (MOCVD). Patent CN103489967A, "A Method for Preparing Gallium Oxide Epitaxial Films and Gallium Oxide Epitaxial Films," discloses a method for preparing gallium oxide epitaxial films using an MOCVD system by adjusting growth parameters, adding auxiliary reactants, and optimizing subsequent processing methods. Patent CN112103175A discloses a vanadium-doped n-type gallium oxide film prepared by a doping process for n-type gallium oxide films. Using radio frequency magnetron sputtering, vanadium-doped n-type gallium oxide films with uniform surfaces, dense film formation, and excellent crystallinity are prepared. Compared to native gallium oxide films, the doping with the Group V element vanadium provides more carriers, significantly improving the photoelectric properties of the n-type gallium oxide film. Patent CN112647130A relates to a method for growing gallium oxide thin films using low-pressure chemical vapor deposition (LPCVD). This method grows gallium oxide epitaxial films using LPCVD, followed by in-situ post-annealing to treat the films. This reduces surface roughness while significantly improving the crystal quality of the Ga2O3 films. Patent CN114775055A discloses a gallium oxide crystal, its preparation method, and its application. This method utilizes the similar lattice matching of gallium phosphate crystals and gallium oxide crystals but with a higher gallium content to achieve reverse epitaxial growth of gallium oxide crystals by inversely oxidizing and transforming gallium phosphate single crystal substrates with argon at high temperature from the outside in.

[0004] However, existing technical solutions for preparing gallium oxide thin films have low preparation efficiency and poor crystallization quality, film density and grain size. How to further improve the preparation efficiency and crystallization quality, film density and grain size of gallium oxide thin films is an urgent problem that needs to be solved. Summary of the Invention

[0005] In view of this, the present application provides a gallium oxide film based on the MPCVD process and a preparation method thereof, aiming to improve the preparation efficiency of the gallium oxide film, as well as improve the crystallization quality, density and grain size of the gallium oxide film.

[0006] In a first aspect, the present application provides a method for preparing a gallium oxide thin film based on an MPCVD process, comprising: The MPCVD process is used to introduce a gallium source, an oxygen source, and a growth gas into the reaction chamber, and a gallium oxide thin film is obtained epitaxially in the reaction chamber.

[0007] Optionally, the steps of using an MPCVD process to introduce a gallium source, an oxygen source, and a growth gas into a reaction chamber and epitaxially forming a gallium oxide thin film in the reaction chamber include: providing a substrate; Pre-treat the substrate to remove surface defects and contaminants; Continuously introducing a gallium source into the reaction chamber; Continuously introducing an oxygen source into the reaction chamber; The microwave power supply is turned on, and a gallium oxide thin film is obtained by epitaxial growth in an atmosphere of growth gas.

[0008] Optionally, when the gallium source is continuously introduced into the reaction chamber, the parameters are as follows: The gallium source temperature is 0℃~50℃, and the pressure of the gallium source bottle is 1×10 3 mbar~2×10 3 mbar, and the carrier gas flow rate is 5 sccm~500 sccm.

[0009] Optionally, the supply ratio of the gallium source to the oxygen source is 0.01~0.1.

[0010] Optionally, when epitaxially growing a gallium oxide thin film, the parameters are as follows: Gallium oxide thin films are epitaxially grown at a growth temperature of 400°C to 600°C and a growth pressure of 50mbar to 200mbar using a microwave power of 1500W to 4000W.

[0011] Optionally, the total flow rate of the growth gas and the oxygen source is 300 sccm-500 sccm, the flow rate of the oxygen source is 3 sccm-150 sccm, and the growth gas includes a carrier gas.

[0012] Optionally, when epitaxially growing the gallium oxide thin film, the microwave power is increased gradually according to the growth time.

[0013] Optionally, the method further includes: The gallium oxide film is annealed.

[0014] Optionally, the step of annealing the gallium oxide film includes: The gallium oxide film is annealed in an argon atmosphere or a vacuum environment at an annealing temperature of 400° C. to 1200° C. for 30 minutes to 120 minutes.

[0015] In a second aspect, the present application provides a gallium oxide thin film based on an MPCVD process, which is manufactured using any of the methods described above.

[0016] The technical solution provided by this application has at least the following beneficial effects: In the first aspect, the present application applies the Microwave Plasma Chemical Vapor Deposition (MPCVD) process to the preparation of gallium oxide thin films. The MPCVD process utilizes the strong cracking effect of microwave plasma to highly activate the oxygen source and enhance the decomposition of the gallium source, thereby increasing the reaction rate of the oxygen source and the gallium source. The use of the MPCVD process to produce gallium oxide thin films can improve the growth efficiency of the gallium oxide thin films (its growth rate is greater than 5μm / h, which is higher than the growth efficiency of traditional processes such as MOCVD).

[0017] In the second aspect, the present application obtains a process parameter formula by optimizing the process parameters of the MPCVD process. The optimized process parameter formula can be used to prepare a gallium oxide film with better density, better crystal quality and grain size. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A flow chart of a method for preparing a gallium oxide thin film based on an MPCVD process according to an embodiment of the present application; Figure 2 A flow chart of a method for preparing a gallium oxide thin film based on an MPCVD process according to another embodiment of the present application; Figure 3 A flowchart of substrate pretreatment according to an embodiment of the present application; Figure 4 A flow chart of a method for preparing a gallium oxide thin film based on an MPCVD process according to another embodiment of the present application; Figure 5 A schematic structural diagram of an MPCVD growth system provided in one embodiment of the present application; Figure 6 A schematic structural diagram of a gallium oxide thin film provided in one embodiment of the present application; Figure 7 This is a SEM image of a prepared gallium oxide film provided in this application; Figure 8 This is a SEM image of the cross section of a prepared gallium oxide film provided in this application.

[0020] The reference numerals are as follows: 1: reaction chamber; 10: substrate; 100: gallium oxide film; 11: substrate stage; 12: transition chamber; 13: atomic emission spectrometer window; 14: observation window; 2: Nitrogen source supply pipeline; 20: Nitrogen source; 21: Manual valve; 22: Flow meter; 23: Pneumatic valve; 24: Gas mixing chamber; 3: oxygen source supply pipeline; 30: oxygen source; 4: Gallium source supply pipeline; 40: Carrier gas source; 41: Supply main pipeline; 42: First branch pipeline; 421: Inlet sub-pipeline; 422: Outlet sub-pipeline; 43: Second branch pipeline; 44: Gallium source; 5: Gas mixing chamber; 6: exhaust gas treatment pipeline; 61: exhaust gas treatment main line; 62: exhaust gas treatment branch line; 601: butterfly valve; 602: molecular pump; 603: exhaust gas treatment device; 604: mechanical pump. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0022] For gallium oxide materials: The industry has long believed that MPCVD is not suitable for gallium oxide growth. The reasons are: 1. Intrinsic damage mechanism: High-energy electrons (>5eV) in the plasma will break the Ga-O bond (bond energy 2.8eV), causing the oxygen vacancy concentration to exceed the device tolerance limit ( 2. Process uncontrollability: The temperature conflict between gallium source vaporization (>50°C) and oxygen source activation (<30°C) results in a precursor utilization rate of less than 20% in traditional reaction chambers.

[0023] In this application, 1. gradient power control is adopted to reduce the plasma energy to 3.8eV at the critical point of 1800W, which is lower than the Ga-O bond breaking threshold; 2. a dual-path carrier gas system (main path for oxygen / auxiliary path for gallium) is used to achieve a precursor utilization rate of >85%.

[0024] Before introducing the technical solution of this application, the inventive concept of this application is briefly introduced: In the first aspect, the present application applies the MPCVD process to the preparation of gallium oxide thin films. The MPCVD process can highly activate the oxygen source and enhance the decomposition of the gallium source by utilizing the strong cracking effect of microwave plasma, thereby increasing the reaction rate of the oxygen source and the gallium source. The use of the MPCVD process to produce gallium oxide thin films can improve the growth efficiency of the gallium oxide thin films (its growth rate is greater than 5μm / h, which is higher than the growth efficiency of traditional MOCVD and other processes).

[0025] Secondly, this application optimizes the process parameters of the MPCVD process to obtain a process parameter formula. The optimized process parameter formula can produce a gallium oxide film with better density, better crystal quality and grain size. The specific process parameter optimization principle is as follows: First, the influence of MPCVD process parameters on film density.

[0026] Increasing microwave power enhances dissociation and activation in the plasma, allowing more high-energy particles to bombard the growth surface and increasing surface atomic mobility. This facilitates filling microvoids formed during growth, promoting a densely packed structure in the film and ultimately improving film density. Sufficient plasma energy can also eliminate pores and defects in situ, preventing the formation of a loose columnar grain boundary structure. Furthermore, gas flow rate and growth pressure influence film density by influencing reactant supply and plasma properties. A moderate oxygen flow rate ensures sufficient oxygen source for the reaction, enabling Ga to be fully oxidized and deposited into a continuous film layer. Insufficient oxygen flow rate can lead to localized oxygen vacancies and underoxidized regions, disrupting the film's coherence and dense structure. Excessive oxygen (excessive oxygen supply ratio) can overcool the plasma or induce rapid saturated nucleation, resulting in the formation of small, isolated grains, which is detrimental to dense growth. Furthermore, increasing growth temperature also promotes densification: higher substrate temperatures enhance surface diffusion, encouraging adatoms to fill low-density sites during migration, reducing pores and defects and significantly improving film density. In general, by precisely controlling the above MPCVD process parameters within the optimized range, a high-density gallium oxide film with a smooth surface and no obvious voids can be obtained.

[0027] Second, the influence of MPCVD process parameters on the crystallinity of thin films.

[0028] Process parameters play a decisive role in the crystal quality (crystallinity) of gallium oxide thin films. Firstly, growth temperature is a key factor influencing the degree of crystallization: higher temperatures provide sufficient thermal energy to orderly align gallium oxide atoms in the lattice, thereby improving crystallinity. This application leverages the plasma-assisted energy characteristics of MPCVD. Even at relatively low substrate temperatures, the high-density plasma provides additional energy to promote crystallization of gallium oxide thin films. Furthermore, increasing microwave power enhances the plasma's effect on the growth surface, allowing crystal nuclei to receive higher energy for further growth and form a more perfect crystal structure. Furthermore, gas composition and supply ratio significantly influence the crystal structure of gallium oxide. Maintaining an appropriate supply ratio of oxygen source to gallium source can prevent lattice oxygen deficiency caused by insufficient oxygen. Oxygen vacancies are common point defects in gallium oxide. Excessive oxygen vacancies disrupt the order of the crystal lattice and reduce crystallinity. Increasing the oxygen supply helps fill these vacancies, improving the lattice integrity and enhancing crystal quality. Through experimental optimization, the present invention selected a microwave power of 1500~4000W, a pressure of 50–200 mbar, and a suitable oxygen / nitrogen flow rate combination to achieve the growth of high crystalline quality gallium oxide thin films.

[0029] Third, the influence of MPCVD process parameters on grain size.

[0030] MPCVD process parameters also affect the grain size of gallium oxide films, which in turn impacts film performance. Generally speaking, higher growth temperatures and sufficient surface energy promote grain growth. As the temperature rises, the diffusion and rearrangement of atoms in the film accelerate, allowing small nuclei to merge and grow, reducing the formation of new nuclei and resulting in an increase in the average grain size. The present invention achieves a higher equivalent growth temperature through the combined effects of substrate heating and plasma deposition, resulting in grain sizes significantly larger than those of conventional low-temperature deposited films, with more refined grains. In addition to temperature, microwave power and atmosphere composition also influence grain size. Appropriately increasing microwave power increases surface active species and boosts growth energy, allowing existing grains to grow more fully and larger. A balance between growth rate and nucleation rate is crucial. By adjusting the supply ratio of Ga source and oxygen and introducing an appropriate amount of nitrogen gas, this process effectively reduces the driving force for supersaturation, preventing the simultaneous formation of too many nuclei and allowing limited nuclei to grow continuously. This increases the average grain size and ensures a uniform grain size distribution. Larger grains mean fewer grain boundaries. This reduction in grain boundary area not only reduces the defect density at the grain boundaries but also improves the overall density of the film. In summary, optimized MPCVD parameters significantly increase the grain size of gallium oxide films, ensuring that the grains are complete and extend throughout the film thickness, which is beneficial for improving device performance and stability.

[0031] Based on the above three points, this application comprehensively optimizes the MPCVD process parameters, so that the MPCVD process can be applied to the preparation of gallium oxide thin films, and ensures that the gallium oxide films prepared by the process parameter formula have better density, crystal quality and grain size.

[0032] Figure 1 This is a flow chart of a method for preparing a gallium oxide thin film based on an MPCVD process according to an embodiment of the present application. Figure 1 , the method steps include: S101, using the MPCVD process, introducing a gallium source, an oxygen source, and a growth gas into a reaction chamber, and epitaxially obtaining a gallium oxide thin film in the reaction chamber.

[0033] In this embodiment, by regulating key process parameters in the MPCVD process, the MPCVD process can be applied to the preparation of gallium oxide thin films. By utilizing the characteristic of the MPCVD process that can efficiently decompose the reaction gas, the preparation efficiency of the gallium oxide thin film and the crystallization quality of the gallium oxide thin film can be improved.

[0034] Figure 2 This is a flow chart of a method for preparing a gallium oxide thin film based on an MPCVD process according to another embodiment of the present application. Figure 2 , the method steps include: S201: Provide a substrate.

[0035] In one example, the substrate may be a single crystal substrate.

[0036] For example, the single crystal substrate may include any one of a silicon substrate, a sapphire substrate, a gallium oxide substrate, a silicon carbide substrate, and the like.

[0037] S202: Pre-treat the substrate to remove surface defects and contaminants.

[0038] See also Figure 3 In one example, step S202 includes: Step 1: ultrasonically clean the substrate.

[0039] In one example, step 1 includes: The substrate was cleaned by ultrasonic cleaning technology using acetone, alcohol, piranha solution and deionized water in sequence, and the cleaned substrate was blown dry using a nitrogen gun.

[0040] Among them, the piranha solution is a mixed solution of H2SO4 and H2O2, with the ratio of H2SO4 to H2O2 being 3:1.

[0041] Step 2: etching the substrate.

[0042] In one example, step 2 includes: The first step is to turn on the water bath switch of the metal source (MO source) cylinder, set the water bath temperature of the source bottle, and switch the constant temperature belt wrapped around the gas pipeline to maintain the gallium source gasification state.

[0043] The second step is to inject nitrogen into the chamber, wait until the reaction chamber reaches normal pressure, open the reaction chamber, send the substrate into the sample chamber, and evacuate the reaction chamber.

[0044] Step 3: When the vacuum degree of the injection chamber reaches 10 -4 Below pa, oxygen is introduced to flush the gas pipeline of the equipment to remove other impurity gases, so that the MPCVD gas channel is filled with pure oxygen.

[0045] Step 4: Turn on the sample stage and rotate it, turn on the microwave power supply, and use oxygen plasma to etch the substrate for 1 to 5 minutes.

[0046] MPCVD is used to etch the single crystal substrate to remove contaminants on the substrate surface, facilitating the formation of a uniform gallium film on the substrate surface.

[0047] In one example, during etching, the microwave power of MPCVD is controlled at 3000W~5000W, the pressure in the reaction chamber is 100mbar~180mbar, and the temperature in the reaction chamber is 600℃~750℃.

[0048] Illustratively, during etching, the microwave power of the MPCVD is 4000 W, the pressure in the reaction chamber is 150 mbar, and the temperature in the reaction chamber is 650°C.

[0049] In one example, the etching gas may include one or more of oxygen and helium.

[0050] In this embodiment, the etching gas is oxygen, which is converted into oxygen plasma to etch the substrate.

[0051] In one example, the rotation rate of the sample stage is 1 to 10 revolutions per minute.

[0052] Exemplarily, the rotation rate of the sample stage is 5 revolutions per minute.

[0053] S203, continuously introducing a gallium source into the reaction chamber.

[0054] In one example, step S203 includes: Open the valve of the carrier gas pipeline, adjust the gallium source temperature, gallium source bottle pressure, main carrier gas and auxiliary carrier gas flow rates, and use argon as the carrier gas to bring the gallium source into the MPCVD chamber.

[0055] In one example, when the gallium source is continuously introduced into the reaction chamber, the parameters are as follows: The gallium source temperature is 0℃~50℃, and the pressure of the gallium source bottle is 1×10 3 mbar~2×10 3 mbar, and the carrier gas flow rate is 5 sccm~500 sccm.

[0056] For example, the gallium source temperature is 20°C, and the pressure of the gallium source bottle is 1.5×10 3 mbar, and the carrier gas flow rate was 100 sccm.

[0057] In one example, the gallium source may be trimethylgallium or triethylgallium.

[0058] Illustratively, the gallium source is trimethylgallium.

[0059] In one example, the carrier gas may be one or more of hydrogen and helium.

[0060] Illustratively, the carrier gas is hydrogen.

[0061] S204, continuously introducing an oxygen source into the reaction chamber.

[0062] In one example, step S204 includes: The oxygen source flow rate is changed, the supply amount of the gallium source and the oxygen source is adjusted, and the oxygen source is introduced into the reaction chamber.

[0063] In one example, the supply ratio of the gallium source to the oxygen source is 0.01-0.1.

[0064] Exemplarily, the supply ratio of the gallium source to the oxygen source is 0.05.

[0065] S205 , turning on the microwave power supply, and epitaxially growing a gallium oxide thin film in an atmosphere of growth gas.

[0066] In one example, step S205 includes: The MPCVD growth parameters such as microwave power, cavity pressure, oxygen flow rate, helium flow rate, etc. are adjusted to grow gallium oxide thin films.

[0067] In one example, when epitaxially growing a gallium oxide thin film, the parameters are as follows: Gallium oxide thin films are epitaxially grown at a growth temperature of 400°C to 600°C and a growth pressure of 50mbar to 200mbar using a microwave power of 1500W to 4000W.

[0068] For example, a gallium oxide thin film is epitaxially grown at a growth temperature of 500° C. and a growth pressure of 150 mbar using a microwave power of 2000 W.

[0069] In another embodiment provided in the present application, when epitaxially growing a gallium oxide thin film, the microwave power is increased in a gradient according to the growth time.

[0070] For example, in stage 1: initial growth, the initial nucleation time is 10 minutes, and a microwave power of 1500W is used.

[0071] A lower power (1500W) was used to ensure that the maximum electron energy of the plasma was <3.8eV (lower than the Ga-O bond breakage threshold) to avoid the generation of oxygen vacancy defects in the initial nucleation layer.

[0072] Phase 2: Transition period, the transition period lasts for 5 minutes, and a microwave power of 1800W is used.

[0073] By gradually increasing the power to the critical point of 1800W, the plasma energy is precisely controlled at 3.8eV (just below the damage threshold but sufficient to activate the reaction gas), achieving a balance of "dissociation without damage".

[0074] Stage 3: Steady-state growth, the steady-state growth duration is 60 minutes, and the microwave power is 2500W~4000W.

[0075] After a stable gallium oxide layer has formed, the power is increased to a higher level (2500W-4000W) to accelerate the precursor dissociation and deposition rate. At this point, the underlying lattice has formed, and the damage resistance is enhanced.

[0076] In one example, the total flow rate of the growth gas and the oxygen source is 300 sccm-500 sccm, the flow rate of the oxygen source is 3 sccm-150 sccm, and the growth gas includes a carrier gas.

[0077] In one example, the carrier gas is hydrogen.

[0078] Figure 4 This is a flow chart of a method for preparing a gallium oxide thin film based on an MPCVD process according to another embodiment of the present application. Figure 4 , the method steps include: S301: Provide a substrate.

[0079] See step S201.

[0080] S302: Pre-treat the substrate to remove surface defects and contaminants.

[0081] See step S202.

[0082] S303, continuously introducing a gallium source into the reaction chamber.

[0083] See step S203.

[0084] S304, continuously introducing an oxygen source into the reaction chamber.

[0085] See step S204.

[0086] S305 , turning on the microwave power supply, and epitaxially growing a gallium oxide thin film in an atmosphere of growth gas.

[0087] See step S205.

[0088] S306 , performing annealing treatment on the gallium oxide film.

[0089] After the growth of the gallium oxide film is completed, the gallium oxide film is annealed and then sampled to complete the preparation of the high-quality gallium oxide film.

[0090] In one example, step S306 includes: The gallium oxide film is annealed in an argon atmosphere or a vacuum environment at an annealing temperature of 400° C. to 1200° C. for 30 minutes to 120 minutes.

[0091] For example, the gallium oxide film is annealed at an annealing temperature of 600° C. in an argon atmosphere for 50 minutes.

[0092] Figure 5 This is a schematic diagram of the structure of the MPCVD growth system provided in one embodiment of the present application. Figure 5 , the MPCVD growth system includes: Reaction chamber 1, used for growing gallium oxide thin films; Helium supply pipeline 2, used for supplying helium into the reaction chamber; Oxygen source supply pipeline 3, used for supplying oxygen source into the reaction chamber; Gallium source supply pipeline 4, used for supplying gallium source into the reaction chamber; The gas mixing chamber 5 is used to mix the gases before they are introduced into the reaction chamber.

[0093] In one example, the reaction chamber 1 has a substrate stage 11 for carrying a substrate 10. The top of the reaction chamber 1 has a transition chamber 12, one side of the reaction chamber 1 has an atomic emission spectrometer window 13, and the other side has an observation window 14.

[0094] In one example, the helium supply pipeline 2 has a helium source 20 , a manual valve 21 , a flow meter 22 , and a pneumatic valve 23 in sequence.

[0095] In one example, the oxygen source supply pipeline 3 has an oxygen source 30 , a manual valve 21 , a flow meter 22 , and a pneumatic valve 23 in sequence.

[0096] In an example, the gallium source supply pipeline 4 includes a main supply line 41 , a first supply branch line 42 , and a second supply branch line 43 .

[0097] The first supply branch 42 includes an inlet sub-path 421 and an outlet sub-path 422. One end of the inlet sub-path is connected to the main supply path 41 and the other end is connected to the gallium source 44. The outlet sub-path 422 is connected to the gallium source 44 at one end and to the main supply path 41 at the other end. The second supply branch 42 connects the inlet sub-path 421 and the outlet sub-path 422.

[0098] In one example, a carrier gas source 40 , a manual valve 21 , a flow meter 22 , and a pneumatic valve 23 are sequentially provided on the main supply line 41 .

[0099] In one example, a pneumatic valve 23 and a manual valve 21 are sequentially provided on the air intake sub-path 421 .

[0100] In one example, a manual valve 21 and a pneumatic valve 23 are sequentially provided on the gas outlet sub-path 422 .

[0101] In one example, a pneumatic valve 23 is provided on the second supply branch 42 .

[0102] In one example, the MPCVD growth system further includes: The tail gas treatment pipeline 6 is used to treat the tail gas in the reaction chamber 1 .

[0103] In one example, the exhaust gas treatment pipeline 6 includes an exhaust gas treatment main line 61 and an exhaust gas treatment branch line 62 , and both ends of the exhaust gas treatment branch line 62 are connected to the exhaust gas treatment main line 61 .

[0104] In one example, a butterfly valve 601 , a molecular pump 602 , a pneumatic valve 23 , an exhaust gas treatment device 603 and a mechanical pump 604 are sequentially arranged on the exhaust gas treatment main path 61 .

[0105] In one example, a pneumatic valve 23 is provided on the exhaust gas treatment branch 62 .

[0106] Combine Figure 5 The MPCVD growth system and the aforementioned Figures 1 to 4 The method steps in this application are given as follows: Example 1: Step 1: Select (100) single crystal silicon as the substrate and treat the substrate according to the standard cleaning process. First, the substrate is ultrasonically cleaned in acetone solution for 10 minutes; second, it is ultrasonically cleaned in ethanol solution for 10 minutes; then, it is ultrasonically cleaned in piranha solution (H2SO4 and H2O2 in a ratio of 3:1) for 10 minutes; then, the cleaned substrate is ultrasonically cleaned in deionized water for 10 minutes. Finally, the substrate is removed and blown dry with nitrogen to complete the cleaning process.

[0107] Step 2: Turn on the water bath switch of the metal source (MO) cylinder and the switch of the thermostatic tape wrapped around the gas pipeline to maintain the gallium source in the vaporized state; Step 3: Introduce high-purity nitrogen into the chamber, wait for the reaction chamber to reach normal pressure, place the substrate into the sample chamber, and evacuate the reaction chamber; open the MPCVD chamber, place the cleaned sample, start the mechanical pump, and when the vacuum degree of the reaction chamber drops below 2 Pa, start the molecular pump and evacuate the back vacuum degree of the reaction chamber to 1×10 -4 Below Pa.

[0108] Step 4: Introduce oxygen at a flow rate of 200 sccm, turn on the microwave power, set the MPCVD microwave power to 4000 W, the pressure to 160 mbar, and the temperature to 600°C, and perform plasma etching on the substrate for 3 minutes.

[0109] Step 5: To make the substrate etching more uniform, start the rotation of the sample stage at 5 rpm.

[0110] Step 6: Open the carrier gas line control valve and introduce the trimethylgallium source into the MPCVD chamber through the carrier gas argon with a carrier gas flow rate of 10 sccm.

[0111] Step 7: Adjust the microwave power and cavity pressure. At this time, the MPCVD microwave power is 4000W, the pressure is 170mbar, the temperature is 650℃, and the growth time is 2h.

[0112] Step 8: After growth, the gallium oxide crystal is annealed using MPCVD. The annealing is performed in a pure argon atmosphere at a temperature of 800° C. for 60 minutes.

[0113] Step 9: Close all air inlet valves, open the MPCVD reaction chamber, and take out the grown gallium oxide epitaxial film.

[0114] Example 2: Step 1: Select a single-crystal sapphire substrate with a (0002) crystal face and treat it according to standard cleaning procedures. First, ultrasonically clean the substrate in acetone for 10 minutes. Next, ultrasonically clean it in ethanol for 10 minutes. Then, ultrasonically clean it in piranha solution (H2SO4:H2O2 in a 3:1 ratio) for 10 minutes. Finally, ultrasonically clean the cleaned substrate in deionized water for 10 minutes. Finally, remove the substrate and blow dry it with nitrogen to complete the cleaning process.

[0115] Step 2: Turn on the water bath switch of the metal source (MO) cylinder and the switch of the thermostatic tape wrapped around the gas pipeline to maintain the gallium source in the vaporized state; Step 3: Introduce high-purity nitrogen into the chamber, wait for the reaction chamber to reach normal pressure, place the substrate into the sample chamber, and evacuate the reaction chamber; open the MPCVD chamber, place the cleaned sample, start the mechanical pump, and when the vacuum degree of the reaction chamber drops below 2 Pa, start the molecular pump and evacuate the back vacuum degree of the reaction chamber to 1×10 -4 Below Pa.

[0116] Step 4: Introduce oxygen at a flow rate of 200 sccm, turn on the microwave power, control the microwave power of MPCVD at 4800 W, the pressure at 175 mbar, and the temperature at 720°C, and perform plasma etching on the substrate for 10 minutes.

[0117] Step 5: To make the substrate etching more uniform, start the rotation of the sample stage at 5 rpm.

[0118] Step 6: Open the carrier gas line control valve and introduce the triethylgallium source into the MPCVD chamber through the carrier gas argon with a carrier gas flow rate of 50 sccm.

[0119] Step 7: Adjust the microwave power and cavity pressure. At this time, the MPCVD microwave power is 3500W, the pressure is 145mbar, the temperature is 550℃, and the growth time is 1.5h.

[0120] Step 8: After growth, the gallium oxide crystal is annealed in a vacuum annealing furnace. The annealing is performed under vacuum at a temperature of 1000° C. for 60 minutes.

[0121] Figure 6 This is a schematic diagram of the structure of the gallium oxide film prepared according to an embodiment of the present application. Figure 6 The gallium oxide film 100 is stacked on the substrate 10, wherein the gallium oxide film 100 is Figures 1 to 4 The method described above was used to prepare the obtained product.

[0122] By analyzing the SEM images, the excellent characteristics of the film of the present invention in terms of density, crystallinity and grain size can be intuitively characterized. Figure 7 As shown in the surface SEM image, the film surface exhibits a continuous, dense, polycrystalline structure: the grains are tightly packed, with clear grain boundaries and no holes, indicating a highly dense film with no obvious defects. Literature comparisons show that a smooth, uniform film surface free of cracks and holes generally indicates low defect density and high quality.

[0123] The SEM surface morphology of the film of the present application is smooth and the particle size is uniform. No loose particles or voids are observed, which proves that the process parameter regulation makes the film dense and continuous. The obvious visibility of the grain outline also shows that the film has been crystallized - if it is an amorphous film, it will be difficult to distinguish the grain structure in the SEM; and the crystal surface of this film is clearly distinguishable, reflecting good crystallinity. In addition, it can be seen from the surface grain size that the film grains are relatively large and evenly distributed, which is consistent with the result of optimizing the process to promote grain growth. The larger the grain, the fewer grain boundaries per unit volume, which further improves the density and crystal integrity of the film.

[0124] Figure 8 The cross-sectional SEM image shows the structural characteristics of the film in the thickness direction. It can also be seen that the gallium oxide film forms a continuous and dense columnar grain structure from the substrate to the surface. The crystal columns are closely connected, and no cracks or pores are found through the film layer. This shows that the film is also densely stacked in the vertical direction, and there are no hole defects inside, which confirms the density of the material. The clear columnar grain morphology on the cross section shows that the film has undergone preferential crystal growth in the vertical direction during the growth process. The grains run through the entire film and the grain boundaries are well bonded, reflecting excellent crystallization quality and mechanical stability. In addition, the interface between the film and the substrate is smooth and there is no sign of peeling, indicating that appropriate pretreatment and growth parameters improve the bonding strength of the film / liner interface and avoid delamination problems caused by loose structure.

[0125] In summary, the SEM characterization results fully demonstrate that by optimizing the MPCVD process parameters, the gallium oxide film prepared in this application has a dense and uniform microstructure, good crystalline morphology and a large grain size. These structural improvements together give the film excellent material properties and application value.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a gallium oxide thin film based on an MPCVD process, characterized in that: include: The MPCVD process is used to introduce a gallium source, an oxygen source, and a growth gas into the reaction chamber, and a gallium oxide thin film is obtained epitaxially in the reaction chamber.

2. The method for preparing a gallium oxide thin film based on MPCVD process according to claim 1, characterized in that: The steps of introducing a gallium source, an oxygen source, and a growth gas into a reaction chamber using an MPCVD process and epitaxially forming a gallium oxide thin film in the reaction chamber include: providing a substrate; Pre-treat the substrate to remove surface defects and contaminants; Continuously introducing a gallium source into the reaction chamber; Continuously introducing an oxygen source into the reaction chamber; The microwave power supply is turned on, and a gallium oxide thin film is obtained by epitaxial growth in an atmosphere of growth gas.

3. The method for preparing a gallium oxide thin film based on MPCVD process according to claim 2, characterized in that: When the gallium source is continuously introduced into the reaction chamber, the parameters are as follows: The gallium source temperature is 0℃~50℃, and the pressure of the gallium source bottle is 1×10 3 mbar~2×10 3 mbar, and the carrier gas flow rate is 5 sccm~500 sccm.

4. The method for preparing a gallium oxide thin film based on MPCVD process according to claim 2, characterized in that: The supply ratio of gallium source to oxygen source is 0.01~0.

1.

5. The method for preparing a gallium oxide thin film based on MPCVD process according to claim 2, characterized in that: When epitaxially growing gallium oxide thin films, the parameters are as follows: Gallium oxide thin films are epitaxially grown at a growth temperature of 400°C to 600°C and a growth pressure of 50mbar to 200mbar using a microwave power of 1500W to 4000W.

6. The method for preparing a gallium oxide thin film based on MPCVD process according to claim 5, characterized in that: The total flow rate of the growth gas and the oxygen source is 300 sccm~500 sccm, the flow rate of the oxygen source is 3 sccm~150 sccm, and the growth gas includes a carrier gas.

7. The method for preparing a gallium oxide thin film based on MPCVD process according to claim 5, characterized in that: When epitaxially growing gallium oxide thin films, the microwave power is increased gradually according to the growth time.

8. The method for preparing a gallium oxide thin film based on MPCVD process according to any one of claims 2 to 7, characterized in that: The method further comprises: The gallium oxide film is annealed.

9. The method for preparing a gallium oxide thin film based on MPCVD process according to claim 8, characterized in that: The steps of annealing the gallium oxide film include: The gallium oxide film is annealed in an argon atmosphere or a vacuum environment at an annealing temperature of 400° C. to 1200° C. for 30 minutes to 120 minutes.

10. A gallium oxide thin film based on MPCVD process, characterized in that: The method according to any one of claims 1 to 9 is used for manufacturing.

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