Gallium oxide structure based on MPCVD and MBE and preparation method thereof

Abstract

The invention provides a gallium oxide structure based on MPCVD and MBE and a preparation method thereof, and belongs to the field of semiconductors. The preparation method of the gallium oxide structure based on MPCVD and MBE comprises the following steps: providing a substrate; carrying out pretreatment on the substrate; performing epitaxy on the surface of the substrate by adopting an MBE process to obtain a gallium film; and introducing a gallium source, an oxygen source and growth gas into the growth cavity by adopting an MPCVD process, and carrying out epitaxy to obtain the gallium oxide thin film. According to the method, the preparation rate, the crystallization quality, the compactness and the grain size of gallium oxide can be improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductors, and in particular to a gallium oxide structure based on MPCVD and MBE and a preparation method thereof. Background Art

[0002] Gallium oxide ( ) is an important semiconductor material, however, due to the limitation of technology level, The application field of the material is relatively narrow, and its application scale lags far behind other semiconductor materials such as gallium nitride (GaN) and silicon carbide (SiC). With the advancement and iteration of technology, the demand for high-power devices is growing, and researchers are gradually turning their attention to gallium oxide materials with better performance. Currently, although the high-power and high-voltage market is mainly dominated by lightly doped silicon metal oxide semiconductors (LDMOS) and SiC Schottky rectifiers, Due to its unique performance advantages, the material has become a potential candidate for solving the ultra-high power market (greater than 1kW).

[0003] The monoclinic β-Ga2O3 structure, as the most thermodynamically stable form, stands out among many crystalline forms. This structural stability is due to its unique lattice arrangement and interatomic interaction, which makes β- It has significant advantages in the field of materials science. It is worth noting that other crystalline forms At temperatures above 750~900℃, it will naturally transform into a stable β- , further confirming its thermodynamic stability.

[0004] β- The material is not only structurally stable, but also attracts much attention for its excellent photoelectric properties and gas-sensitive characteristics. Its wide band gap, high breakdown field strength and excellent photoelectric conversion efficiency give it broad application prospects in the field of semiconductor power devices. In addition, β- It has high sensitivity to specific gases and therefore has great potential in the field of gas sensors. The high transparency and conductivity of β- It has important application value in the fields of solar cells, flat panel display technology, etc. At the same time, its unique solar-blind ultraviolet detection capability also gives it a unique advantage in the field of photoelectric detection.

[0005] Although β- Materials have so many excellent properties and application fields, but its preparation process and performance optimization is still the focus of current research. There are many methods for preparing gallium oxide film materials at present, mainly including: radio frequency magnetron sputtering (RF-MS), pulsed laser deposition (PLD), electron beam evaporation (EBV), molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD) and the like. Patent CN103489967A discloses a method for preparing a gallium oxide epitaxial film using a MOCVD system, by adjusting the growth parameters, adding auxiliary reactants and optimizing the subsequent processing method to prepare a gallium oxide epitaxial film; patent CN112103175A discloses a vanadium-doped n-type gallium oxide film prepared by a doping process, which is prepared by a radio frequency magnetron sputtering method, and a vanadium-doped n-type gallium oxide film with uniform surface, dense film and good crystallinity is prepared. Compared with the intrinsic gallium oxide film, the doping of the fifth element vanadium provides more carriers, and significantly improves the photoelectric performance of the n-type gallium oxide film. Patent CN112647130A relates to a method for growing a gallium oxide film by low-pressure chemical vapor deposition. The method grows a gallium oxide epitaxial film by low-pressure chemical vapor deposition, and then performs in-situ post-annealing treatment on the film to reduce the surface roughness and significantly improve the crystal quality of the film. Patent CN114775055A discloses a gallium oxide crystal and a preparation method and application thereof. The phosphogallate single crystal substrate is oxidized from the outside to the inside by argon at high temperature to convert and inversely epitaxially grow the gallium oxide crystal.

[0006] How to continue to improve the crystal quality, growth rate and density of gallium oxide is still a technical problem being studied. SUMMARY

[0007] Therefore, the present application provides a gallium oxide structure based on MPCVD and MBE and a preparation method thereof, aiming to improve the preparation rate, crystalline quality and density of gallium oxide on the basis of the prior art.

[0008] In a first aspect, a preparation method of a gallium oxide structure based on MPCVD and MBE is provided, which comprises: providing a substrate; pretreating the substrate; adopting an MBE process to epitaxially obtain a gallium film on the surface of the substrate; adopting an MPCVD process to introduce a gallium source, an oxygen source and a growth gas into a growth cavity to epitaxially obtain a gallium oxide film.

[0009] Optionally, the step of adopting an MBE process to epitaxially obtain a gallium film on the surface of the substrate comprises: at a growth temperature of 650-850℃ and a growth pressure of 5x10 -1 Pa-5x10 3 at a rotation speed of 2-20rpm.

[0010] Optionally, after the gallium film is made, the gallium film is transferred into the MPCVD growth chamber by vacuum interconnection technology.

[0011] Optionally, the step of epitaxially obtaining the gallium oxide film by introducing the gallium source, the oxygen source and the growth gas into the growth chamber by MPCVD process comprises: continuously introducing the gallium source into the MPCVD growth chamber; continuously introducing the oxygen source into the MPCVD growth chamber; turning on the microwave power to epitaxially obtain the gallium oxide film in the atmosphere of the growth gas.

[0012] Optionally, when the gallium source is continuously introduced into the MPCVD growth chamber, the process parameters are as follows: the gallium source temperature is 0-50℃, the pressure of the gallium source bottle is 1x10 3 mbar-2x10 3 mbar, and the carrier gas flow is 5-500sccm.

[0013] Optionally, the supply ratio of the gallium source to the oxygen source is 0.01-0.1.

[0014] Optionally, when the microwave power is turned on to epitaxially obtain the gallium oxide film in the atmosphere of the growth gas, the parameters used are as follows: the microwave power is 1500-4000W, the growth temperature is 400-600℃, the growth pressure is 50-200mbar, the growth gas comprises a carrier gas, the total flow of the growth gas and the oxygen source is 300-500sccm, and the oxygen flow is 3-150sccm.

[0015] Optionally, the method for preparing the gallium oxide structure based on MPCVD and MBE further comprises: in-situ annealing treatment of the gallium oxide film.

[0016] Optionally, the step of in-situ annealing treatment of the gallium oxide structure comprises: annealing treatment of the gallium oxide structure under vacuum atmosphere at an annealing temperature of 600-1200℃ for 20-60min.

[0017] In a second aspect, a gallium oxide structure is provided, which is prepared by the method according to any one of the above aspects.

[0018] The technical solution provided by this application has at least the following beneficial effects: First, the gallium oxide film was grown using the MPCVD and MBE vacuum interconnection method. The gallium film was first made by the MBE process, and then the MPCVD process was used to grow gallium oxide on the surface of the gallium film. The gallium film made by the MBE process can be grown in an ultra-high vacuum environment ( ) under precise control of gallium atomic deposition, forming an atomically flat single-crystal film with a thickness of 5-50nm and a surface roughness of <0.3nm, completely eliminating the island growth defects of traditional vapor deposition. The gallium film, as a pure metal reaction source, directly undergoes a surface oxidation reaction with highly active oxygen plasma in the subsequent MPCVD process, circumventing the C-H bond cleavage process required by the organic gallium source, significantly reducing the activation energy of the oxidation reaction, thereby increasing the growth rate of the gallium oxide film. The MPCVD process for producing gallium oxide 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 between the oxygen source and the gallium source. The MPCVD process for producing gallium oxide films can improve the growth efficiency of gallium oxide films (its growth rate is greater than 5μm / h, which is higher than the growth efficiency of traditional processes such as MOCVD).

[0019] Secondly, the present application optimizes the process parameters of the MPCVD process to obtain a process parameter formula, and uses the optimized process parameter formula to prepare gallium oxide, which can improve the crystallization quality, density and grain size of gallium oxide crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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.

[0021] Figure 1 A flow chart of a method for preparing a gallium oxide structure based on MPCVD and MBE provided in one embodiment of the present application; Figure 2 A flow chart of substrate pretreatment provided in one embodiment of the present application; Figure 3 A flow chart of a method for preparing a gallium oxide structure based on MPCVD and MBE provided in another embodiment of the present application; Figure 4 A flow chart of a method for preparing a gallium oxide structure based on MPCVD and MBE provided in another embodiment of the present application; Figure 5A structural schematic diagram of a gallium oxide structure provided by an embodiment of the present application; Figure 6 A structural schematic diagram of a growth system of a gallium oxide structure provided by an embodiment of the present application; Figure 7 An SEM surface diagram of a gallium oxide structure provided by an embodiment of the present application; Figure 8 An SEM cross-sectional diagram of a gallium oxide structure provided by another embodiment of the present application.

[0022] The reference signs are as follows: 100: sample inlet cavity; 110: MPCVD growth cavity; 120: MBE growth cavity; 130: high-low temperature annealing cavity; 140: annular mechanical hand cavity; 150: annular mechanical hand; 160: gate valve. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0024] For gallium oxide material: the industry has long believed that MPCVD is not suitable for gallium oxide growth, because: 1. intrinsic damage mechanism: high-energy electrons (>5eV) in the plasma will break the Ga-O bond (bond energy 2.8eV), resulting in an oxygen vacancy concentration exceeding the device tolerance limit (>1012cm-2) ). 2. Process uncontrollability: the temperature contradiction between gallium source vaporization (>50℃) and oxygen source activation (<30℃) makes the traditional reaction chamber precursor utilization rate <20%. 3. Thermodynamic conflict: β- Phase transition occurs above 800℃, while MPCVD requires a stable plasma above 900℃, causing material decomposition to be unavailable.

[0025] In the present application, 1. Gradient power control is adopted to reduce the plasma energy to 3.8eV below the Ga-O bond breaking threshold at the 1800W critical point; 2. A dual-path carrier gas system (main path oxygen / auxiliary path gallium) realizes a precursor utilization rate >85%. 3. Combined with MBE pre-deposited gallium film, low-temperature epitaxy at 650℃ is realized to avoid the phase transition temperature.

[0026] Before introducing the technical solutions of the present application, the inventive concept of the present application is briefly introduced: First, the gallium oxide film was grown using the MPCVD and MBE vacuum interconnection method. The gallium film was first made by the MBE process, and then the MPCVD process was used to grow gallium oxide on the surface of the gallium film. The gallium film made by the MBE process can be grown in an ultra-high vacuum environment ( ) under precise control of gallium atomic deposition, forming an atomically flat single-crystal film with a thickness of 5-50nm and a surface roughness of <0.3nm, completely eliminating the island growth defects of traditional vapor deposition. The gallium film, as a pure metal reaction source, directly undergoes a surface oxidation reaction with highly active oxygen plasma in the subsequent MPCVD process, circumventing the C-H bond cleavage process required by the organic gallium source, significantly reducing the activation energy of the oxidation reaction, thereby increasing the growth rate of the gallium oxide film. The MPCVD process for producing gallium oxide 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 between the oxygen source and the gallium source. The MPCVD process for producing gallium oxide films can improve the growth efficiency of gallium oxide films (its growth rate is greater than 5μm / h, which is higher than the growth efficiency of traditional processes such as MOCVD).

[0027] Secondly, this application optimizes the process parameters of the MPCVD process to obtain a process parameter formula. Using the optimized process parameter formula to prepare gallium oxide can improve the crystallization quality, density and grain size of gallium oxide crystals. The specific optimization principle is as follows: First, the influence of MPCVD process parameters on film density.

[0028] 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.

[0029] Second, the influence of MPCVD process parameters on the crystallinity of thin films.

[0030] Process parameters on the crystalline quality (crystallinity) of thin films play a decisive role. First of all, the growth temperature is a key factor affecting the degree of crystallinity: higher temperatures provide sufficient thermal energy for atoms to arrange in an orderly manner in the lattice positions, thereby improving the degree of crystallinity. The present application takes advantage of the characteristics of MPCVD plasma-assisted energy, i.e. even at relatively low substrate temperatures, by providing additional energy through high-density plasma, it can also promote the crystallization of thin films. In addition, increasing the microwave power can enhance the effect of plasma on the growth surface, allowing the crystal nucleus to obtain higher energy for further growth and form a more perfect crystal structure. At the same time, the gas composition and supply ratio have a significant impact on the crystal structure. Ensuring the appropriate supply ratio of oxygen source and gallium source can avoid lattice oxygen deficiency caused by insufficient oxygen. Oxygen vacancies are common point defects in , and too many oxygen vacancies will destroy the order of the lattice and reduce the degree of crystallinity; increasing the supply of oxygen helps to fill oxygen vacancies and makes the lattice more complete, improving the crystal quality. Through experimental optimization, the present application selects 1500-4000W microwave power, 50-200mbar pressure and appropriate / flow combination to achieve the growth of thin films with high crystalline quality.

[0031] Third, the influence of MPCVD process parameters on the grain size.

[0032] MPCVD process parameters also affect the grain size of thin films, which in turn relates to the performance of thin films. Generally speaking, higher growth temperatures and sufficient surface energy help the grain to grow. When the temperature rises, the diffusion and rearrangement process of atoms in the film accelerates, small crystal nuclei can merge and grow, reducing the occurrence of new nucleation, resulting in an increase in the average grain size. The present application realizes a higher equivalent growth temperature under the combined action of substrate heating and plasma, and the grain size is significantly larger than that of conventional low-temperature deposited thin films, and the grain is more perfect. In addition to temperature, microwave power and atmosphere composition also affect the grain size. Appropriately increasing the microwave power can increase the surface active species and growth energy, allowing the existing grains to grow more fully and become larger; it is necessary to control the balance between growth rate and nucleation rate. By adjusting the supply ratio of Ga source and and introducing an appropriate amount of The gas, the process effectively reduces the supersaturation driving force, avoids the simultaneous appearance of too many crystal nuclei, and allows the limited crystal nuclei to continue to grow. This increases the average size of the crystal grains, and the uniform distribution of the crystal grain size. Larger crystal grains mean a reduction in the number of grain boundaries, and the reduction in the area of the grain boundaries not only reduces the defect density at the grain boundaries, but also improves the overall density of the film. In summary, the optimized MPCVD parameters make The film grain size is significantly improved, the crystal grains are complete and penetrate the film thickness, which is beneficial to the improvement of device performance and stability.

[0033] According to the above three points, the process parameters of the MPCVD are comprehensively optimized, so that the MPCVD process can be applied to the preparation of gallium oxide films, and the density, crystalline quality and grain size of the gallium oxide films prepared by the process parameters are relatively good.

[0034] In a third aspect, the preparation method is carried out in a high vacuum environment, reducing the pollution of impurities to the gallium oxide film, and the prepared gallium oxide film has high purity and good crystal quality. The prepared gallium oxide film can be widely used in the fields of semiconductor power devices, gas sensitive sensors, transparent conductive films and solar blind ultraviolet detectors.

[0035] Figure 1 An embodiment provided by the present application provides a preparation method flow chart of a gallium oxide structure based on MPCVD and MBE. Referring to Figure 1 The method steps include: S101, providing a substrate.

[0036] In an example, the substrate can be a single crystal substrate.

[0037] Illustratively, the single crystal substrate can be any one of a silicon substrate, a sapphire substrate, a gallium nitride, a gallium oxide and a silicon carbide substrate.

[0038] S102, pretreating the substrate.

[0039] Referring to Figure 2 In an example, step S102 includes: Step 1, cleaning the substrate.

[0040] In an example, step 1 includes: The substrate is sequentially placed in acetone, alcohol and deionized water for ultrasonic cleaning for 15 minutes, and then dried with dry nitrogen and used.

[0041] Step 2, etching the substrate.

[0042] In an example, step 2 includes: Firstly, the substrate is sent into a sample chamber, and the sample chamber is vacuumized; Second step, when the sample cavity vacuum degree to 1x10 -5 Pa, open the shutter valve, and the substrate is sent into the MPCVD chamber by the ring-shaped mechanical hand, the microwave power is turned on, and the mixed gas of hydrogen and oxygen is used as the etching gas for plasma etching treatment of the substrate. The etching time is 5-30 min.

[0043] In an example, when the substrate is etched, the etching process parameter formula is as follows: When etching, the microwave power of MPCVD is 3000-6000 W, the pressure is 100-200 mbar, and the temperature is 600-900℃.

[0044] Illustratively, when etching, the microwave power of MPCVD is 4000 W, the pressure is 150 mbar, and the temperature is 700℃.

[0045] In an example, the etching gas can be a mixed gas composed of any one or more of hydrogen and oxygen.

[0046] In the foregoing example, the etching gas is a mixed gas of hydrogen and oxygen.

[0047] By cleaning and etching the substrate, the dirt and impurities on the surface of the substrate are removed. In addition, using MPCVD to etch the single crystal substrate can reduce the wetting angle of gallium on the surface of the silicon substrate while removing the contaminants on the surface of the substrate, facilitating the formation of a uniform gallium film on the surface of the silicon substrate.

[0048] After the pretreatment of the substrate is completed, the substrate is transferred from the MPCVD growth chamber to the MBE growth chamber using vacuum interconnection technology, and the growth of the gallium film is prepared. Vacuum interconnection technology can avoid contamination of the substrate during transfer.

[0049] It should be noted that the vacuum interconnection technology here refers to connecting the MPCVD growth chamber and the MBE growth chamber in a vacuum environment, and separating the MPCVD growth chamber and the MBE growth chamber by a separation device (such as a shutter valve). When the substrate needs to be transferred, the separation device is opened, and the substrate is transferred between the MPCVD growth chamber and the MBE growth chamber by another transfer device (such as a ring-shaped mechanical hand).

[0050] S103, using MBE process to epitaxially obtain a gallium film on the surface of the substrate.

[0051] In an example, step S103 includes: Adjusting the MBE chamber pressure, sample stage temperature, and gallium source temperature to achieve epitaxial growth of the gallium film to the desired thickness.

[0052] The specific growth formula of step S103 is as follows: At a growth temperature of 650-850℃ and a growth pressure of 5x10 -1 Pa, a gallium film is epitaxially obtained at a rotation speed of 2-20 rpm. 3 Pa, a gallium film is epitaxially obtained at a rotation speed of 2-20 rpm.

[0053] Exemplarily, at a growth temperature of 700℃ and a growth pressure of 2x10 3 Pa, a gallium film is epitaxially obtained at a rotation speed of 2-20 rpm.

[0054] After the gallium film is prepared, the gallium film is transferred into the MPCVD growth cavity by vacuum interconnection technology.

[0055] By vacuum interconnection technology, the gallium film can be prevented from being contaminated.

[0056] S104, a gallium source, an oxygen source and a growth gas are introduced into the growth cavity by MPCVD process to epitaxially obtain a gallium oxide film.

[0057] Referring to Figure 3 In an example, step S104 includes: Step 1, continuously introduce a gallium source into the MPCVD growth cavity.

[0058] Open the valve of the carrier gas pipeline, adjust the gallium source temperature, the gallium source bottle pressure and the carrier gas flow rate, and use argon as the carrier gas to bring the gallium source into the MPCVD cavity.

[0059] In an example, when continuously introducing a gallium source into the MPCVD growth cavity, the process parameters are as follows: The gallium source temperature is 0-50℃, the gallium source bottle pressure is 1x10 3 mbar-2x10 3 mbar, and the carrier gas flow rate is 5-500sccm.

[0060] Exemplarily, the gallium source temperature is 20℃, the gallium source bottle pressure is 1.5x10 3 mbar, and the carrier gas flow rate is 100sccm.

[0061] In an example, the gallium source can be trimethylgallium or triethylgallium.

[0062] Exemplarily, the gallium source is trimethylgallium.

[0063] In an example, the carrier gas can be one or more of hydrogen and helium.

[0064] Exemplarily, the carrier gas is hydrogen.

[0065] Step 2, continuously input oxygen source into the MPCVD growth cavity.

[0066] In one example, step 2 includes: Change the oxygen source flow, adjust the supply amount of the gallium source and the oxygen source, and input the oxygen source into the reaction cavity.

[0067] In one example, the supply ratio of the gallium source to the oxygen source is 0.01-0.1.

[0068] Illustratively, the supply ratio of the gallium source to the oxygen source is 0.05.

[0069] Step 3, turn on the microwave power source, and epitaxially obtain a gallium oxide film in the atmosphere of the growth gas.

[0070] In one example, step 3 includes: Adjust the growth parameters of the MPCVD, such as microwave power, cavity pressure, oxygen flow, and helium flow, to grow the gallium oxide film.

[0071] In one example, when the microwave power source is turned on and the gallium oxide film is epitaxially obtained in the atmosphere of the growth gas, the following parameters are used: The gallium oxide film is epitaxially obtained in an environment with a growth temperature of 400-600°C and a growth pressure of 50-200 mbar, using a microwave power of 1500-4000 W.

[0072] In one example, the total flow of the growth gas and the oxygen source is 300-500 sccm, and the oxygen source flow is 3-150 sccm. The growth gas includes a carrier gas.

[0073] In one example, the carrier gas is hydrogen.

[0074] In another embodiment provided in the present application, when the gallium oxide film is epitaxially obtained, the microwave power is gradually increased according to the growth time.

[0075] Illustratively, stage 1: initial growth, the initial nucleation time is 10 minutes, and the microwave power is 1500 W.

[0076] A lower power (1500 W) is used to ensure that the highest electron energy of the plasma is <3.8 eV (lower than the Ga-O bond breaking threshold), and to avoid oxygen vacancy defects in the initial nucleation layer.

[0077] Stage 2: transition period, the transition period is 5 minutes, and the microwave power is 1800 W.

[0078] Step by step power up to the critical point 1800W, the plasma energy is precisely controlled at 3.8eV (just below the damage threshold but enough to activate the reaction gas), to achieve the balance of "dissociation without damage".

[0079] Phase 3: Steady-state growth, the steady-state growth time is 60 minutes, and the microwave power is 2500W~4000W.

[0080] After the stable gallium oxide layer has been formed, the power is raised to a higher level (2500-4000W) to accelerate the precursor dissociation and deposition rate. At this time, the bottom lattice has been formed, and the damage resistance has been enhanced.

[0081] Figure 4 A preparation method flow chart of a gallium oxide structure based on MPCVD and MBE is provided for another embodiment of the present application. Referring to Figure 4 , the method steps include: S201, providing a substrate.

[0082] Referring to step S101.

[0083] S202, pretreating the substrate.

[0084] Referring to step S102.

[0085] S203, using the MBE process to epitaxially obtain a gallium film on the surface of the substrate.

[0086] Referring to step S103.

[0087] S204, using the MPCVD process to introduce a gallium source, an oxygen source, and a growth gas into the growth cavity to epitaxially obtain a gallium oxide thin film.

[0088] Referring to step S104.

[0089] S205, in-situ annealing treatment of the gallium oxide thin film.

[0090] In one example, step S205 includes: Annealing treatment of the gallium oxide structure under a vacuum atmosphere, the annealing temperature is 600℃~1200℃, and the annealing time is 20min~60min.

[0091] In one example, the gallium oxide thin film is transferred from the MPCVD growth cavity to the high-low temperature annealing cavity for annealing by vacuum interconnection technology.

[0092] Figure 5 A structure schematic diagram of a gallium oxide structure is provided for an embodiment of the present application. Referring to Figure 5 , the gallium oxide structure includes: A substrate 10, a gallium film 20 and a gallium oxide thin film 30 laminated on the surface of the substrate.

[0093] Figure 6 The structure diagram of the gallium oxide structure growth system provided by an embodiment of the present application is shown in FIG. 1. Figure 6 The gallium oxide growth system comprises: a sample loading chamber 100; an MPCVD growth chamber 110 for etching treatment or epitaxial growth by an MPCVD process; an MBE growth chamber 120 for epitaxial growth by an MBE process; a high-low temperature annealing chamber 130 for annealing treatment; a ring-shaped robot chamber 140, which is in vacuum interconnection with the sample loading chamber 100, the MPCVD growth chamber 110, the MBE growth chamber 120 and the high-low temperature annealing chamber 130 in sequence, and the ring-shaped robot chamber 140 is provided with a ring-shaped robot 150 for transferring substrates between the chambers, and the sample loading chamber 100, the MPCVD growth chamber 110, the MBE growth chamber 120 and the high-low temperature annealing chamber 130 are provided with gate valves 160 between the ring-shaped robot chamber 140 for opening or closing the channels between the chambers when needed.

[0094] In combination with the growth system of Figure 6 and the method of Figures 1 to 4 a specific embodiment is given as follows: Embodiment 1 Step 1: Select (100) single crystal silicon as the substrate, and process the substrate according to the standard cleaning treatment steps. First, ultrasonic clean the substrate in acetone solution for 15 min; second, ultrasonic clean it in ethanol solution for 15 min; then, ultrasonic clean the above cleaned substrate in deionized water solution for 15 min, and finally take out the substrate and dry it with nitrogen, completing the cleaning.

[0095] Step 2: Open the sample loading chamber and put in the cleaned sample, start the turbo molecular pump when the reaction chamber vacuum degree is below 2 Pa, and then open the gate valve to send the substrate from the sample loading chamber to the ring-shaped robot UFO chamber.

[0096] Step 3: Open the gate valve between the ring-shaped robot chamber and the MPCVD chamber, send the substrate into the MPCVD chamber, close the gate valve, and introduce 500 sccm of mixed gas of hydrogen and oxygen into the MPCVD chamber, wherein the oxygen flow is 10 sccm, turn on the microwave power, control the MPCVD power at 4800 W, the pressure is 160 mbar, and the temperature is 650℃, and perform plasma etching treatment on the substrate for 15 min.

[0097] Step 4: Following the previous process, the etched substrate is transferred to the MBE growth chamber using a ring manipulator for epitaxial growth of the gallium film; MBE chamber pressure: 1×10 2 Pa; sample stage temperature: 700℃; gallium source temperature: 850℃; growth time: 60min; sample stage rotation speed: 15rpm.

[0098] Step 5: A circular manipulator was used to transfer the MBE-grown gallium film into the MPCVD chamber for epitaxial growth of a gallium oxide thin film. The MPCVD power was controlled at 4000W, pressure at 170mbar, temperature at 650°C, and oxygen at a flow rate of 40sccm for 30 minutes.

[0099] Step 6: After the gallium oxide film growth process is completed, the gallium oxide film is transferred to the annealing chamber using a ring manipulator, and the gallium oxide film is annealed in a vacuum atmosphere at an annealing temperature of 900° C. for 45 minutes.

[0100] Step 7: After annealing is completed, the cooling rate is controlled at 1°C / min. After the gallium oxide film has cooled, the sample is transferred to the injection chamber and the grown gallium oxide film is taken out. The gallium oxide epitaxial film prepared by the above method is obtained.

[0101] Example 2: Step 1: Select a single-crystal sapphire substrate with a (0006) crystal plane and treat it according to standard cleaning procedures. First, ultrasonically clean the substrate in acetone for 15 minutes. Then, ultrasonically clean it in ethanol for 15 minutes. Finally, ultrasonically clean the cleaned substrate in deionized water for 15 minutes. Finally, remove the substrate and blow dry it with nitrogen to complete the cleaning process.

[0102] Step 2: Open the injection chamber and put the cleaned sample in. When the vacuum degree of the reaction chamber is below 2 Pa, start the turbomolecular pump and pump the back vacuum degree of the reaction chamber to 1×10 -5 Pa, and then open the gate valve to send the substrate from the injection chamber into the annular robot chamber.

[0103] Step 3: Open the gate valve between the annular manipulator chamber and the MPCVD chamber, send the substrate into the MPCVD chamber, close the gate valve, introduce 500 sccm of hydrogen into the MPCVD chamber, turn on the microwave power, the microwave power of MPCVD is 6000 W, the growth pressure is 180 mbar, the growth temperature is 850°C, and the substrate is plasma etched for 10 minutes.

[0104] Step 4: According to the previous flow, the etched substrate is transferred into the MBE growth chamber by the ring-shaped robot for epitaxial growth of a gallium film; MBE chamber pressure: 5x10 -2 Pa; sample stage temperature: 750℃; growth time: 90min, sample stage rotation speed: 5rpm.

[0105] Step 5: Further, the MBE-grown gallium film is transferred into the MPCVD chamber by the ring-shaped robot for epitaxial growth of a gallium oxide film. The MPCVD power is controlled at 4200W, the pressure is 160mbar, the temperature is 600℃, the growth gas is oxygen, the flow rate is 50sccm, and the growth time is 60min.

[0106] Step 6: After the gallium oxide film growth process is completed, the gallium oxide film is transferred to the annealing chamber by the ring-shaped robot, and the gallium oxide film is annealed in a vacuum atmosphere, with an annealing temperature of 1000℃ and an annealing time of 30min.

[0107] Step 7: After annealing is completed, the cooling rate is controlled at 3℃ / min, and after the gallium oxide film is cooled, the sample is transferred to the sample chamber, and the grown gallium oxide film is removed. The gallium oxide epitaxial film prepared by the above method.

[0108] Through analysis of the SEM image, the excellent characteristics of the film in terms of density, crystallinity and grain size can be directly represented. As shown in the surface SEM image, the film surface presents a continuous and dense polycrystalline particle structure: the grains are tightly packed, and the grain boundaries are clear without pores, indicating that the film is highly dense and has no obvious defects. Literature comparison shows that a smooth and uniform film surface without cracks and pores often means low defect density and high quality. Figure 7

[0109] The SEM surface morphology of the film of the present application is flat and the particle size is uniform, and no loose particles or voids are observed, which proves that the process parameters are controlled to make the film dense and continuous. The clear outline of the crystal grains also indicates that the film has been crystallized - if it is an amorphous film, the grain structure will be difficult to distinguish in SEM; while the clear and distinguishable crystal faces of the film reflect good crystallinity. In addition, from the surface grain size, it can be seen that the film crystal grains are relatively large and uniformly distributed, which is consistent with the result of optimizing the process to promote grain growth. The larger the grain size, the fewer the grain boundaries in unit volume, which further improves the density and crystal integrity of the film.

[0110] 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.

[0111] 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.

[0112] 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 structure based on MPCVD and MBE, characterized in that: The method for preparing the gallium oxide structure based on MPCVD and MBE comprises: providing a substrate; Pre-treating the substrate; Using the MBE process, a gallium film is epitaxially grown on the substrate surface; The MPCVD process is used to introduce a gallium source, an oxygen source, and a growth gas into the growth chamber to obtain a gallium oxide thin film by epitaxy.

2. The method for preparing a gallium oxide structure based on MPCVD and MBE according to claim 1, characterized in that: The steps of epitaxially growing a gallium film on a substrate using the MBE process include: The growth temperature is 650℃~850℃ and the growth pressure is 5×10 -1 Pa~5×10 3 In a Pa environment, a gallium film is obtained by epitaxial growth at a rotation speed of 2rpm~20rpm.

3. The method for preparing a gallium oxide structure based on MPCVD and MBE according to claim 1, characterized in that: After the gallium film is produced, vacuum interconnection technology is used to transfer the gallium film to the MPCVD growth chamber.

4. The method for preparing a gallium oxide structure based on MPCVD and MBE according to claim 1, characterized in that: The steps of introducing a gallium source, an oxygen source, and a growth gas into a growth chamber by MPCVD process to epitaxially obtain a gallium oxide thin film include: Continuously introduce gallium source into the MPCVD growth chamber; Continuously introduce an oxygen source into the MPCVD growth 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.

5. The method for preparing a gallium oxide structure based on MPCVD and MBE according to claim 4, characterized in that: When the gallium source is continuously introduced into the MPCVD growth chamber, the process 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.

6. The method for preparing a gallium oxide structure based on MPCVD and MBE according to claim 4, characterized in that: The supply ratio of gallium source to oxygen source is 0.01~0.

1.

7. The method for preparing a gallium oxide structure based on MPCVD and MBE according to claim 4, characterized in that: When the microwave power is turned on and the gallium oxide thin film is grown epitaxially in the atmosphere of the growth gas, the parameters used are as follows: The microwave power is 1500W~4000W, the growth temperature is 400℃~600℃, the growth pressure is 50mbar~200mbar, the growth gas includes carrier gas, the total flow rate of growth gas and oxygen source is 300sccm~500sccm, and the oxygen source flow rate is 3sccm~150sccm.

8. The method for preparing a gallium oxide structure based on MPCVD and MBE according to any one of claims 1 to 7, characterized in that: The method for preparing the gallium oxide structure based on MPCVD and MBE further includes: The gallium oxide film is subjected to in-situ annealing.

9. The method for preparing a gallium oxide structure based on MPCVD and MBE according to claim 8, characterized in that: The step of performing in-situ annealing on the gallium oxide structure comprises: The gallium oxide structure is annealed in a vacuum atmosphere at a temperature of 600° C. to 1200° C. for a time of 20 min to 60 min.

10. A gallium oxide structure, characterized in that The gallium oxide structure is manufactured by the method according to any one of claims 1 to 9.

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