Growth Method of Gallium Oxide Thin Film

Abstract

This application belongs to the technical field of semiconductor material preparation, and provides a method for growing gallium oxide thin films, including the following steps: providing a reaction chamber and an inclined substrate, and placing the inclined substrate in the reaction chamber; after controlling the temperature and pressure in the reaction chamber to be a first temperature and a first pressure respectively, introducing a gallium source and an oxygen source into the reaction chamber to form a first gallium oxide layer on the inclined substrate; after controlling the temperature and pressure in the reaction chamber to be a second temperature and a second pressure respectively, introducing a gallium source and an oxygen source into the reaction chamber to form a second gallium oxide layer on the first gallium oxide layer; wherein, the first temperature is greater than the second temperature, and the first pressure is less than the second pressure. During the growth process of the first gallium oxide layer and the second gallium oxide layer, a high-temperature and low-pressure growth environment is conducive to the rapid two-dimensional growth of gallium oxide materials, and a low-temperature and high-pressure growth environment is conducive to the stress release of gallium oxide materials, hinders the extension of defects, reduces dislocation defects, and improves the surface quality of gallium oxide thin films.

Description

Technical Field

[0001] This application relates to the technical field of semiconductor material preparation, and particularly to a method for growing gallium oxide thin films. Background Art

[0002] Gallium oxide (Ga2O3) is a direct-bandgap wide-bandgap semiconductor material. Due to its large bandgap width and breakdown field strength, it has attracted much attention in the semiconductor industry. Gallium oxide materials have good thermal stability and chemical stability, with a transmittance in the visible light region reaching over 80%. At the same time, they have a strong absorption effect on the ultraviolet light region with wavelengths of 200nm - 300nm. In power semiconductors, the bandgap width of gallium oxide materials can reach 4.9eV, which is much larger than that of silicon carbide and gallium nitride, and the theoretical breakdown field strength can reach 8MV / cm. Based on these excellent properties, gallium oxide materials have important applications in fields such as detection and power devices.

[0003] Currently, gallium oxide thin films applied to semiconductor technology are mainly prepared by heteroepitaxy on substrates. Due to the high decomposition temperature of gallium oxide materials, the crystal quality of the grown gallium oxide materials is poor, the surface is relatively rough, and as the film thickness increases, the surface roughness becomes more serious, seriously affecting the yield and reliability of devices, resulting in a serious lag in the research and development and application of gallium oxide devices.

[0004] Therefore, there is an urgent need for a new method for growing gallium oxide thin films to solve the above problems existing in the prior art. Summary of the Invention

[0005] The purpose of this application is to provide a method for growing gallium oxide thin films to solve the problem of serious surface roughness of gallium oxide thin films in the prior art and effectively improve the surface quality of gallium oxide thin films.

[0006] To achieve the above purpose, the method for growing gallium oxide thin films provided in this application includes the following steps:

[0007] S1: Provide a reaction chamber and an inclined substrate, and place the inclined substrate in the reaction chamber;

[0008] S2: Control the temperature in the reaction chamber to a first temperature, control the pressure in the reaction chamber to a first pressure, and then introduce a gallium source and an oxygen source into the reaction chamber to form a first gallium oxide layer on the inclined substrate;

[0009] S3: Control the temperature in the reaction chamber to a second temperature, control the pressure in the reaction chamber to a second pressure, and then introduce a gallium source and an oxygen source into the reaction chamber to form a second gallium oxide layer on the first gallium oxide layer;

[0010] Among them, the first temperature is not lower than 1000 °C, and the second temperature does not exceed 1000 °C;

[0011] The first pressure does not exceed 50 mbar, the second pressure is not lower than 20 mbar, the first temperature is greater than the second temperature, and the first pressure is less than the second pressure;

[0012] The flow rate of the gallium source introduced in step S3 is not lower than the flow rate of the gallium source introduced in step S2.

[0013] Optionally, the temperature difference between the first temperature and the second temperature does not exceed 600 °C, and the pressure difference between the second pressure and the first pressure does not exceed 95 mbar.

[0014] Optionally, the temperature difference between the first temperature and the second temperature is not lower than 200 °C, and the pressure difference between the second pressure and the first pressure is not lower than 5 mbar.

[0015] Optionally, the first temperature is 1000 °C to 1300 °C, the first pressure is 5 mbar to 50 mbar, the second temperature is 600 °C to 1000 °C, and the second pressure is 40 mbar to 100 mbar.

[0016] Optionally, the bevel angle of the beveled substrate is 1° to 20°, and the beveling direction is any one of the (0001) crystal plane deviating towards the (11-20) crystal plane, the (1-102) crystal plane, or the (10-10) crystal plane, or any one of the (11-21) crystal plane deviating towards the (11-20) crystal plane or the (1-102) crystal plane.

[0017] Optionally, the beveled substrate is any one of a sapphire substrate, a silicon carbide substrate, or a silicon substrate. The beveling direction of the sapphire substrate is the (0001) crystal plane deviating towards the (11-20) crystal plane. The beveling direction of the silicon carbide substrate is the (0001) crystal plane deviating towards the (1-102) crystal plane or the (10-10) crystal plane. The beveling direction of the silicon substrate is the (11-21) crystal plane deviating towards the (11-20) crystal plane or the (1-102) crystal plane.

[0018] Optionally, the bevel angle of the sapphire substrate is 1° to 10°;

[0019] The bevel angle of the silicon carbide substrate is 5° to 15°;

[0020] The bevel angle of the silicon substrate is 8° to 15°.

[0021] Optionally, the beveled substrate is a silicon substrate. After the completion of step S1 and before the execution of step S2, the following steps are further included: controlling the temperature in the reaction chamber to a third temperature, controlling the pressure in the reaction chamber to a third pressure, and introducing an aluminum source and an oxygen source into the reaction chamber to form a buffer layer on the beveled substrate, where the third temperature is higher than the second temperature and the third pressure is lower than the second pressure;

[0022] After forming the buffer layer, step S2 is executed to grow the first gallium oxide layer on the buffer layer.

[0023] Optionally, the temperature difference between the third temperature and the second temperature is 200~600 °C, and the pressure difference between the second pressure and the third pressure is 5 mbar~95 mbar.

[0024] Optionally, the third temperature is 1000 °C~1300 °C, and the third pressure is 5 mbar~50 mbar.

[0025] Optionally, the step of introducing the aluminum source and the oxygen source into the reaction chamber includes: controlling the flow rate ratio of the oxygen source to the aluminum source to be 10:1~70:1, and the ratio of the molar flow rate of the oxygen-containing reactant in the oxygen source to the molar flow rate of the aluminum-containing reactant in the aluminum source to be 400:1~1000:1.

[0026] Optionally, the step of introducing the aluminum source and the oxygen source into the reaction chamber includes: controlling the flow rate of the aluminum source to be 30 sccm~60 sccm, controlling the flow rate of the oxygen source to be 600 sccm~1000 sccm, and controlling the duration of introducing the oxygen source and the aluminum source to be 10 min~60 min.

[0027] Optionally, the aluminum source includes an organometallic compound of aluminum or metallic aluminum, the oxygen source includes an oxygen-containing gas, and the gallium source includes an organometallic compound of gallium or metallic gallium.

[0028] Optionally, in steps S2 and S3, the flow rate ratio of the oxygen source to the gallium source is controlled to be 10:1~70:1, and the ratio of the molar flow rate of the oxygen-containing reactant in the oxygen source to the molar flow rate of the gallium-containing reactant in the gallium source is controlled to be 400:1~3000:1.

[0029] Optionally, in step S2, the flow rate of the gallium source is controlled to be 30 sccm~60 sccm, the flow rate of the oxygen source is controlled to be 600 sccm~2000 sccm, and the duration of introducing the oxygen source and the gallium source is controlled to be 10 min~60 min.

[0030] Optionally, in step S3, control the flow rate of the gallium source to be 30 sccm to 100 sccm, control the flow rate of the oxygen source to be 1000 sccm to 5000 sccm, and control the duration of introducing the oxygen source and the gallium source to be 5 min to 120 min.

[0031] Optionally, after performing step S3, the following steps are further included:

[0032] S4: Repeat steps S2 and S3 to complete the n - cycle growth process, where n is a positive integer greater than 1.

[0033] Optionally, step S3 further includes continuously introducing the oxygen source into the reaction chamber until the temperature in the reaction chamber reaches the second temperature and the pressure in the reaction chamber reaches the second pressure.

[0034] Optionally, steps S2 and S3 further include controlling the beveled substrate to rotate around the axis of the reaction chamber at a rate of 20 rpm to 200 rpm.

[0035] Compared with the prior art, the method for growing a gallium oxide thin film provided by this application has at least the following beneficial effects:

[0036] In the method for growing a gallium oxide thin film of this application, a first gallium oxide layer is grown at the first temperature and the first pressure through step S1, and a second gallium oxide layer is grown at the second temperature and the second pressure through step S2. Control the first temperature to be not lower than 1000 °C, the second temperature to be not higher than 1000 °C, the first pressure to be not higher than 50 mbar, the second pressure to be not lower than 20 mbar, and the first temperature is greater than the second temperature, the first pressure is less than the second pressure. The flow rate of the gallium source introduced in step S3 is not lower than the flow rate of the gallium source introduced in step S2, so that it is beneficial to the rapid two - dimensional growth of the gallium oxide material during the growth of the first gallium oxide layer. And the substrate used is a beveled substrate, which can form a multi - step structure, enabling the gallium oxide material to form a step - flow growth mode on the growth surface, realizing rapid merging, and then forming a flat growth surface; further, it also makes it beneficial to the stress release of the gallium oxide material during the growth of the second gallium oxide layer, hindering the extension of some defects, reducing dislocation defects, improving the surface quality of the formed gallium oxide thin film, and thus improving the product yield. Description of the Drawings

[0037] To more clearly illustrate the technical solutions of the embodiments of this application, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of this application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0038] Figure 1 It shows a schematic flow chart of the method for growing a gallium oxide thin film provided by an embodiment of the present application.

[0039] Figure 2 It shows a schematic structural diagram of a substrate provided by an embodiment of the present application.

[0040] Figure 3 It shows a schematic structural diagram of a first gallium oxide layer and a second gallium oxide layer provided by an embodiment of the present application.

[0041] Figure 4 It shows a schematic flow chart of the method for growing a gallium oxide thin film provided by an alternative embodiment of the present application.

[0042] Figure 5 It shows a schematic structural diagram of forming a buffer layer on a substrate provided by an embodiment of the present application.

[0043] Figures 6 to 8 They respectively show schematic structural diagrams of three different stages during the deposition of gallium oxide material on a substrate provided by an embodiment of the present application.

[0044] Figure 9 and Figure 10 They respectively show schematic structural diagrams of two different gallium oxide thin films with a stacked structure provided by an embodiment of the present application.

[0045] Figure 11 It shows a schematic structural diagram of a MOCVD system provided by Embodiment 1 of the present application.

[0046] Figure 12 and Figure 13 They respectively show a surface morphology diagram and a schematic RC curve diagram of a gallium oxide thin film prepared according to Embodiment 1 of the present application.

[0047] Figure 14 and Figure 15 They respectively show a surface morphology diagram and a schematic RC curve diagram of a gallium oxide thin film prepared according to Embodiment 2 of the present application.

[0048] Figure 16 and Figure 17 They respectively show a surface morphology diagram and a schematic RC curve diagram of a gallium oxide thin film prepared according to Embodiment 3 of the present application.

[0049] Figure 18 It shows a schematic RC curve diagram of a gallium oxide thin film prepared according to Embodiment 4 of the present application.

[0050] Figure 19 It shows a schematic structural diagram of a HVPE system provided by Embodiment 5 of the present application.

[0051] Figure 20 Schematic diagram of the RC curve of the gallium oxide thin film prepared in Example 5 of the present application.

[0052] Figure 21 Schematic diagram of the RC curve of the gallium oxide thin film prepared in Example 6 of the present application.

[0053] Schematic illustration of reference numerals:

[0054] 11. Substrate; 12. Buffer layer; 13. First gallium oxide layer; 14. Second gallium oxide layer; 61. Injection device; 62. Carrying device; 63. Rotating device; 64. Heating device; 71. First introduction channel; 72. Second introduction channel; 73. Metal source boat; 74. Carrying base; 75. Exhaust channel. Detailed implementation manners

[0055] To make the technical objectives, technical solutions, and technical effects of the present application clearer, the technical solutions in the present application will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated herein can be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of the present application is not intended to limit the scope of the present application to be protected, but merely represents the selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0057] In the description of the present application, it should be noted that the description referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0058] Referring to Figure 1 , this embodiment provides a method for growing a gallium oxide thin film, including steps S1 to S3, specifically including:

[0059] Step S1: Provide a reaction chamber and an obliquely cut substrate, and place the obliquely cut substrate in the reaction chamber;

[0060] Step S2: After controlling the temperature in the reaction chamber to be the first temperature and the pressure in the reaction chamber to be the first pressure, introduce a gallium source and an oxygen source into the reaction chamber to form a first gallium oxide layer on the beveled substrate;

[0061] Step S3: After controlling the temperature in the reaction chamber to be the second temperature and the pressure in the reaction chamber to be the second pressure, introduce a gallium source and an oxygen source into the reaction chamber to form a second gallium oxide layer on the first gallium oxide layer, where the first temperature is greater than the second temperature and the first pressure is less than the second pressure.

[0062] Specifically, in steps S1 to S3, the first temperature is not lower than 1000 °C, the second temperature does not exceed 1000 °C, the first pressure does not exceed 50 mbar, the second pressure is not lower than 20 mbar, and the first temperature is greater than the second temperature and the first pressure is less than the second pressure. The flow rate of the gallium source introduced in step S3 is not lower than the flow rate of the gallium source introduced in step S2, so that the growth rate of the second gallium oxide layer is not lower than the growth rate of the first gallium oxide layer, in order to improve the efficiency of preparing the gallium oxide thin film. Place the substrate in the reaction chamber, control the temperature and pressure of the reaction chamber to be the first temperature and the first pressure respectively, and introduce a gallium source and an oxygen source into the reaction chamber. At this time, the growth environment in the reaction chamber is conducive to the rapid two-dimensional growth of the gallium oxide material. And because the substrate is a beveled substrate, its growth surface can have a continuous bevel angle formed by a multi-level step structure, so that the gallium oxide material forms a step flow growth mode on the growth surface, realizing the rapid merging between different order surfaces, which is conducive to the formation of a flat growth surface; then control the temperature and pressure in the reaction chamber to be the second temperature and the second pressure respectively, and introduce a gallium source and an oxygen source into the reaction chamber, so that the process of growing the second gallium oxide layer is conducive to the stress release of the gallium oxide material, hinders the extension of defects, reduces dislocation defects, and improves the surface quality of the formed gallium oxide thin film; it can be seen that this method can improve the film quality and product yield while taking into account the production efficiency.

[0063] The following will specifically describe the method for growing a gallium oxide thin film provided in this embodiment with reference to the drawings. It should be noted that the above order does not strictly represent the process order of the method for growing a gallium oxide thin film protected by this application, and those skilled in the art can make changes according to the actual processing steps.

[0064] In step S1, the beveled substrate 11 has an inclined growth surface. Optionally, referring to Figure 2 , a multi-level step structure can be formed on the growth surface of the beveled substrate 11 to facilitate the growth of the gallium oxide material on the growth surface of the beveled substrate 11.

[0065] In this embodiment, the beveled substrate 11 can be a substrate made of sapphire substrate, silicon carbide substrate, silicon substrate or other suitable materials. The growth surface of the beveled substrate 11 is inclined. For example, a multi-step structure can be obtained by processing the upper surface of the horizontally placed beveled substrate 11, thereby forming an inclined growth surface. The specific processing method is a conventional technical means in the art.

[0066] The bevel angle of the beveled substrate 11 is 1° to 20°. For example, the bevel angle of the beveled substrate 11 can be 1°, 5°, 8°, 10°, 15°, 20° or other suitable angles to form an inclined growth surface.

[0067] In an alternative embodiment, referring to Figure 2 , the growth surface of the beveled substrate 11 is provided with a continuous bevel angle formed by a multi-step structure. The bevel angle of the beveled substrate 11 is 1° to 20°. The bevel direction of the beveled substrate 11 is any one of the (0001) plane deviating towards the (11-20) plane, the (1-102) plane or the (10-10) plane, or any one of the (11-21) plane deviating towards the (11-20) plane or the (1-102) plane.

[0068] In an alternative embodiment, the bevel angle is 1° to 10°, and the beveled substrate 11 is, for example, a sapphire substrate with the (0001) plane deviating towards the (11-20) plane.

[0069] In an alternative embodiment, the bevel angle is 5° to 15°, and the beveled substrate 11 is, for example, a silicon carbide substrate with the (0001) plane deviating towards the (10-10) plane or the (1-102) plane.

[0070] In an alternative embodiment, the bevel angle is 8° to 15°, and the beveled substrate 11 is, for example, a silicon substrate with the (11-21) plane deviating towards the (11-20) plane or the (1-102) plane.

[0071] In step S2, the structure of the first gallium oxide layer 13 formed on the growth surface of the beveled substrate 11 is as Figure 3 shown. Specifically, the temperature and pressure of the reaction chamber are controlled to be the first temperature and the first pressure respectively, and the first temperature is greater than the second temperature, and the first pressure is less than the second pressure, so that the reaction chamber has an environment suitable for the growth of the first gallium oxide layer 13. Among them, the first temperature is not lower than 1000 °C, and the first pressure does not exceed 50 millibars (mbar). The first temperature and the first pressure are conditions conducive to the growth of gallium oxide materials, which can enhance the surface migration ability of atoms, and thus provide a favorable two-dimensional growth environment for the first gallium oxide layer 13 to achieve the rapid growth of the first gallium oxide layer 13.

[0072] In an alternative embodiment, the first temperature is 1000°C to 1300°C. For example, the first temperature can be 1000°C, 1100°C, 1200°C, 1300°C or other suitable temperatures. The first pressure is 5 mbar to 50 mbar. For example, the first pressure can be 5 mbar, 10 mbar, 30 mbar, 50 mbar or other suitable pressures.

[0073] In step S2 of this embodiment, the gallium source includes an organometallic compound of gallium and / or metallic gallium as the gallium-containing reactant, and the oxygen source includes an oxygen-containing reactant as the oxygen-containing reactant. The oxygen-containing reactant can be, for example, an oxygen-containing gas. Among them, the gallium-containing reactant and the oxygen-containing reactant are substances participating in the reaction for generating the gallium oxide thin film.

[0074] In steps S2 and S3 of some embodiments, the gallium source further includes a carrier gas for carrying the gallium-containing reactant, such as at least one of argon, nitrogen, hydrogen chloride or other suitable carrier gases.

[0075] In steps S2 and S3 of some embodiments, the oxygen source further includes a carrier gas for carrying the oxygen-containing reactant, such as at least one of argon, nitrogen or other suitable carrier gases.

[0076] In step S2 of some embodiments, the ratio of the molar flow rate of the oxygen-containing reactant in the oxygen source to the molar flow rate of the gallium-containing reactant in the gallium source is controlled to be 400:1 to 3000:1.

[0077] In step S2 of some embodiments, the ratio of the molar flow rate of the oxygen-containing reactant in the oxygen source to the molar flow rate of the gallium-containing reactant in the gallium source can also be controlled to be 400:1 to 2300:1.

[0078] In step S2, the gallium source, the oxygen source, the flow rate of the gallium source, the flow rate of the oxygen source, and the growth time of the first gallium oxide layer 13 can be set according to actual needs. The gallium-containing reactant in the gallium source is, for example, trimethylgallium, metallic gallium or other suitable substances, and the oxygen-containing reactant in the oxygen source is, for example, nitrous oxide, oxygen, ozone or other suitable substances.

[0079] In step S2 of an alternative embodiment, the step of introducing the gallium source and the oxygen source into the reaction chamber includes: controlling the flow rate ratio of the oxygen source to the gallium source to be 10:1 to 70:1.

[0080] In step S2 of an alternative embodiment, the duration of introducing the oxygen source and the gallium source is controlled to be 10 min to 60 min.

[0081] In step S2 of the optional embodiment, the flow rate of the gallium source is controlled to be 30 sccm to 60 sccm, and the flow rate of the oxygen source is controlled to be 600 sccm to 2000 sccm; for example, the flow rate of the gallium source can be 30 sccm, 40 sccm, 50 sccm, 60 sccm or other appropriate values, and the flow rate of the oxygen source is 600 sccm, 1000 sccm, 1200 sccm, 1500 sccm, 1800 sccm, 2000 sccm or other appropriate values. By controlling the flow rates of the oxygen source and the gallium source in step S2 and the growth time of the first gallium oxide layer 13, it is possible to adjust the diffusion of each source gas in combination with the control of the first temperature and the first pressure, and control the thickness of the first gallium oxide layer 13 to ensure that the film has good surface properties during the gas-phase growth reaction process.

[0082] In the optional embodiment, referring to Figure 4 , after step S1 is completed and before step S2 is executed, the following steps are further included:

[0083] S01: Control the temperature in the reaction chamber to be the third temperature, control the pressure in the reaction chamber to be the third pressure, and introduce an aluminum source and an oxygen source into the reaction chamber to form a buffer layer on the beveled substrate; wherein, the third temperature is higher than the second temperature, and the third pressure is lower than the second pressure.

[0084] In step S01, the buffer layer 12 formed on the beveled substrate 11 is as Figure 5 shown. By growing the buffer layer 12 on the beveled substrate 11, the thermal stress of the beveled substrate 11 can be alleviated, film defects can be reduced. As a transition layer for growing gallium oxide materials, the buffer layer can reduce lattice mismatch, improve the surface morphology of the substrate, and promote the two-dimensional growth and uniform growth of gallium oxide materials.

[0085] In the optional embodiment, the beveled substrate 11 is a silicon substrate, and step S01 is executed after step S1 is completed and before step S2 is executed. Since the lattice constants of silicon and gallium oxide are quite different, directly depositing gallium oxide on silicon easily causes significant dislocations and / or stresses at the interface. More importantly, under the conditions of the first temperature and the first pressure, when depositing gallium oxide materials, gallium is likely to erode into the silicon substrate, affecting the film quality. The lattice constant of aluminum oxide is between that of silicon and gallium oxide, which can effectively alleviate lattice mismatch, reduce interface defects, provide a barrier to prevent gallium erosion, and improve the quality of the gallium oxide film.

[0086] In an alternative embodiment, the aluminum source includes an organometallic compound of aluminum or metallic aluminum. As the aluminum-containing reactant, the oxygen source includes an oxygen-containing reactant, such as an oxygen-containing gas. Herein, the aluminum-containing reactant and the oxygen-containing reactant are the substances participating in the reaction during the formation of the buffer layer. The aluminum-containing reactant in the aluminum source is, for example, trimethylaluminum, metallic aluminum, or other suitable substances, and the oxygen-containing reactant in the oxygen source is, for example, oxygen or other suitable substances. Optionally, the buffer layer 12 can be an aluminum oxide layer or other suitable material layer.

[0087] In step S01 of some embodiments, the aluminum source further includes a carrier gas for carrying the aluminum-containing reactant, such as at least one of argon, nitrogen, and hydrogen chloride.

[0088] In step S01 of some embodiments, the oxygen source further includes a carrier gas for carrying the oxygen-containing reactant, such as at least one of argon and nitrogen.

[0089] In an alternative embodiment, the third temperature is 1000°C to 1300°C, and the third pressure is 5 mbar to 50 mbar. The third temperature is, for example, 1000°C, 1100°C, 1200°C, 1300°C, or other suitable values, and the third pressure is, for example, 5 mbar, 10 mbar, 20 mbar, 30 mbar, 40 mbar, 50 mbar, or other suitable values.

[0090] In an alternative embodiment, the third pressure is, for example, 5 mbar to 10 mbar.

[0091] In an alternative embodiment, the temperature difference between the third temperature and the second temperature does not exceed 600°C, and the pressure difference between the second pressure and the third pressure does not exceed 95 mbar.

[0092] In an alternative embodiment, the temperature difference between the third temperature and the second temperature is not less than 200°C, and the pressure difference between the second pressure and the third pressure is not less than 5 mbar.

[0093] In an alternative embodiment, it is also possible to control the pressure difference between the second pressure and the third pressure not to exceed 55 mbar.

[0094] In step S01, the flow rates of the aluminum source and the oxygen source and the reaction time of the buffer layer can be set according to actual needs. Optionally, the step of introducing the aluminum source and the oxygen source into the reaction chamber includes: controlling the flow rate ratio of the oxygen source to the aluminum source to be 10:1 to 70:1, where the flow rate ratio of the oxygen source to the aluminum source can be understood as the volume flow rate ratio.

[0095] In step S01 of an alternative embodiment, the duration of introducing the oxygen source and the aluminum source is controlled to be 10 min to 60 min.

[0096] In step S01 of the alternative embodiment, the step of controlling the flow rate ratio of the oxygen source to the aluminum source to be 10:1 to 70:1 includes: controlling the flow rate of the aluminum source to be 30 sccm to 60 sccm; the flow rate of the aluminum source can be, for example, 30 sccm, 40 sccm, 50 sccm, 60 sccm or other suitable values, and controlling the flow rate of the oxygen source to be 600 sccm to 1000 sccm. The flow rate of the oxygen source can be, for example, 600 sccm, 700 sccm, 800 sccm, 900 sccm, 1000 sccm or other suitable values.

[0097] In step S01 of the alternative embodiment, the ratio of the molar flow rate of the oxygen-containing reactant in the oxygen source to the molar flow rate of the aluminum-containing reactant in the aluminum source is 400:1 to 1000:1.

[0098] In this embodiment, the buffer layer 12, the first gallium oxide layer 13, and the second gallium oxide layer 14 can be grown by atomic layer deposition (ALD), metal-organic chemical vapor deposition (MOCVD), pulsed laser deposition (PLD), hydride vapor phase epitaxy (HVPE), molecular beam epitaxy (MBE), or other suitable methods.

[0099] In the prior art, due to the complex growth process, high cost, poor mechanical strength and conductivity of the gallium oxide single crystal substrate, it cannot meet the applications of some semiconductor devices. Usually, a hetero-substrate is used for the vapor growth of gallium oxide. However, due to the large difference in the thermal expansion coefficients between the hetero-substrate and the gallium oxide material, there is also a large lattice mismatch between the two, and the vapor growth reaction is prone to generate a high dislocation density, which in turn has an adverse effect on the surface properties such as roughness of the gallium oxide layer.

[0100] This application uses the beveled substrate 11, which can form a multi-level step structure on its growth surface. Combining the control of the first temperature and the first pressure in step S2, the obtained gallium oxide material is deposited at the steps on the growth surface and gradually grows and extends in the two-dimensional direction at the steps. Subsequently, the film layers deposited on each step are gradually merged, and then transformed into a two-dimensional growth mode, which can promote the step flow mode of crystal growth, thereby reducing the dislocation density. Specifically: The surface of the beveled substrate 11 is regularly arranged with atomic-height steps. In step S2, referring to Figures 6 to 8 , at the initial stage of gallium oxide growth, it is deposited on each step. Step merging occurs between adjacent atomic steps to form a micro-step, and step merging will continue to occur during the subsequent growth process, forming macroscopic steps on the film surface. When the film layer on the high step merges with the film layer on the low step, some dislocations (dislocations growing in the vertical direction) in the film layer on the low step will be blocked by the laterally growing film layer on the high step and terminated, thereby reducing the dislocation density of the thin film.

[0101] In this embodiment, the bevel angle of the beveled substrate 11 is controlled to be 1° to 20°. When the bevel angle of the beveled substrate 11 is too large, it is difficult for atoms to adhere to the step edges during the thin film deposition process, making it difficult to achieve the merging between steps and easily leading to the transformation from the two-dimensional layer growth mode to the three-dimensional island growth mode, resulting in poor thin film uniformity. When the bevel angle of the beveled substrate 11 is too small, the step flow growth mode will be restricted, increasing defects such as dislocations in the thin film.

[0102] In step S3 of this embodiment, growing the second gallium oxide layer 14 on the first gallium oxide layer 13 is as Figure 3 shown. The working conditions in the reaction chamber are a growth environment suitable for growing the second gallium oxide layer 14. The temperature and pressure of the reaction chamber are respectively controlled to be the second temperature and the second pressure, and the second temperature is less than the first temperature, and the second pressure is greater than the first pressure. And the flow rate of the gallium source introduced in step S3 is controlled to be not lower than the flow rate of the gallium source introduced in step S2, so as to have an environment suitable for growing the second gallium oxide layer 14 in the reaction chamber and make the growth rate of the second gallium oxide layer 14 not lower than the growth rate of the first gallium oxide layer 13. Among them, the second temperature does not exceed 1000 °C, and the second pressure is not lower than 20 millibars (mbar). The growth conditions of the second temperature and the second pressure make it conducive to stress release during the growth of the second gallium oxide layer 14, hinder the extension of defects, reduce dislocation defects, improve the surface quality of the grown gallium oxide thin film, and thus improve the product yield.

[0103] In an alternative embodiment, the second pressure can also be controlled to be not lower than 40 mbar.

[0104] In an alternative embodiment, the second temperature is 600 °C to 1000 °C. For example, the second temperature can be 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C or other suitable temperatures, and the second pressure is 40 mbar to 100 mbar. For example, the second pressure can be 40 mbar, 50 mbar, 60 mbar, 80 mbar, 90 mbar, 100 mbar or other suitable pressures.

[0105] In an alternative embodiment, the temperature difference between the first temperature and the second temperature does not exceed 600 °C, and the pressure difference between the second pressure and the first pressure does not exceed 95 mbar. Optionally, the temperature difference between the first temperature and the second temperature is not lower than 200 °C, and the pressure difference between the second pressure and the first pressure is not lower than 5 mbar.

[0106] In an alternative embodiment, the pressure difference between the second pressure and the first pressure can also be controlled to be not more than 55 mbar.

[0107] In step S2, control the growth of the first gallium oxide layer 13 at a first temperature and a first pressure. In step S3, control the growth of the second gallium oxide layer 14 at a second temperature lower than the first temperature and a second pressure higher than the first pressure. In step S2, high-temperature growth promotes the decomposition of the gallium source and promotes the migration rate of gallium on the surface to be within a suitable range. Combining low-pressure control can appropriately control the gas-phase reaction rate, which is beneficial to promoting the step-flow mode of crystal growth and the lateral merging of steps, thereby reducing the dislocation density and achieving rapid growth. Considering that high-temperature reactions will exacerbate the difference in thermal expansion coefficients and lattice mismatch between the hetero-substrate and the thin film, low-pressure control is not conducive to the denseness of the thin film. Therefore, in step S3, grow gallium oxide at the second temperature and the second pressure, and control the temperature difference between the first temperature and the second temperature and the pressure difference between the second pressure and the first pressure within a suitable range. Release the thermal stress through the temperature reduction and high-pressure control in step S3, promote the densification of the thin film, and regulate the uniform distribution of stress.

[0108] In step S3 of this embodiment, the gallium source includes an organometallic compound of gallium and / or metallic gallium as the gallium-containing reaction substance, and the oxygen source includes an oxygen-containing reaction substance as the oxygen-containing reaction substance. The oxygen-containing reaction substance can be, for example, an oxygen-containing gas. The flow rates of the gallium source, the oxygen source, the gallium source, the oxygen source, and the growth time of the second gallium oxide layer 14 can be set according to actual needs. The gallium-containing reaction substance in the gallium source is, for example, trimethylgallium, metallic gallium, or other suitable substances, and the oxygen-containing reaction substance in the oxygen source is, for example, nitrous oxide, oxygen, ozone, or other suitable substances.

[0109] In step S3 of the alternative embodiment, the step of introducing the gallium source and the oxygen source into the reaction chamber includes: controlling the flow rate ratio of the oxygen source to the gallium source to be 10:1 to 70:1.

[0110] In step S3 of the alternative embodiment, control the ratio of the molar flow rate of the oxygen-containing reaction substance in the oxygen source to the molar flow rate of the gallium-containing reaction substance in the gallium source to be 400:1 to 3000:1.

[0111] In step S3 of the alternative embodiment, it is also possible to control the ratio of the molar flow rate of the oxygen-containing reaction substance in the oxygen source to the molar flow rate of the gallium-containing reaction substance in the gallium source to be 400:1 to 2300:1.

[0112] In step S3 of the alternative embodiment, control the duration of introducing the oxygen source and the gallium source to be 5 min to 120 min.

[0113] In step S3 of the optional embodiment, the step of controlling the flow rate ratio of the oxygen source to the gallium source to be 10:1 to 70:1 includes: controlling the flow rate of the gallium source to be 30 sccm to 100 sccm, and controlling the flow rate of the oxygen source to be 1000 sccm to 5000 sccm; for example, the flow rate of the gallium source can be 30 sccm, 40 sccm, 50 sccm, 60 sccm, 80 sccm, 90 sccm, 100 sccm or other suitable values, and the flow rate of the oxygen source is 1000 sccm, 2000 sccm, 2400 sccm, 3000 sccm, 4000 sccm, 4500 sccm, 4800 sccm, 5000 sccm or other suitable values.

[0114] In step S3 of the optional embodiment, the flow rate of the introduced gallium source is controlled to be not lower than the flow rate of the gallium source introduced in step S2, so as to increase the growth rate and improve the process efficiency.

[0115] In the optional embodiment, referring to Figure 4 , after completing step S3, the following steps may further be included:

[0116] S4: Repeatedly execute the above-mentioned step S2 and step S3 to complete the n - cycle growth process, where n is a positive integer greater than 1.

[0117] In step 4, completing one execution of step S2 and S3 is regarded as one cycle growth process. Referring to Figure 9 and Figure 10 , the prepared gallium oxide thin film is a laminated structure, including a plurality of first gallium oxide layers 13 and second gallium oxide layers 14 alternately laminated in sequence. Optionally, the gallium oxide thin film can be, for example, a 4 - layer laminated structure, including two first gallium oxide layers 13 and two second gallium oxide layers 14. The first gallium oxide layer 13 and the second gallium oxide layer 14 are alternately laminated in sequence. The gallium oxide thin film can also be a 10 - layer laminated structure, a 20 - layer laminated structure, a 40 - layer laminated structure or a laminated structure with other suitable numbers of layers. The specific value of n can be set according to actual needs.

[0118] Through the above - mentioned cycle growth process, a gallium oxide thin film with a laminated structure can be formed on the beveled substrate 11. When the gallium oxide is rapidly grown to a certain extent (for example, a certain thickness) through step S2, and then timely switched to step S3 for thermal stress release, a gallium oxide thin film with a designed thickness, good surface performance and low dislocation density can be prepared.

[0119] In steps S2 and S3 of the optional embodiment, the method further includes: controlling the beveled substrate to rotate around the axis of the reaction chamber at a rate of 20 rpm to 200 rpm to further enhance the uniformity of the gallium oxide thin film. For example, the beveled substrate 11 can be controlled to rotate at 20 rpm, 60 rpm, 100 rpm, 150 rpm, 200 rpm or other appropriate rotation speeds.

[0120] In the optional embodiment, step S3 further includes continuously introducing an oxygen source into the reaction chamber until the temperature in the reaction chamber is controlled to be a second temperature and the pressure in the reaction chamber is a second pressure.

[0121] The following will further illustrate the method for growing a gallium oxide thin film provided by the present application in combination with some specific embodiments.

[0122] Example 1

[0123] This embodiment provides a method for growing a gallium oxide thin film, and the gallium oxide thin film is grown by using a MOCVD system, including steps S1 to S3, and the specific steps are as follows.

[0124] Step S1: Provide a reaction chamber and a beveled substrate, and place the beveled substrate in the reaction chamber. The reaction chamber is a MOCVD reaction chamber, and the beveled substrate 11 is a sapphire substrate with a (0001) crystal plane deviated from the (11-20) crystal plane by 10°.

[0125] Specifically, the structure of the reaction chamber is as Figure 11 shown, including an injection device 61, a carrier device 62, a rotation device 63, and a heating device 64. The injection device 61 is located at the top of the reaction chamber, and the injection device 61 and the carrier device 62 are oppositely arranged along the axial direction of the reaction chamber and are located above the carrier device 62. A wafer slot (not marked in the figure) is provided on the top surface of the carrier device 62, and the beveled substrate 11 (not marked in the figure) is accommodated in the wafer slot (not marked in the figure). The injection device 61 provides a process medium (such as a gallium source, an oxygen source, an aluminum source, etc., or other media carried by auxiliary purging) that purges along the axial direction of the carrier device to the top surface of the carrier device 62 according to process requirements. The heating device 64 is located at the bottom of the reaction chamber and below the carrier device 62, and heat is provided to the carrier device 62 through the heating device 64 to transfer heat to the beveled substrate 11 to reach the reaction temperature required by the process.

[0126] In this embodiment, during the process, the carrier device 62 is driven by the rotation device 63 to rotate around the axis of the reaction chamber to facilitate the uniform mixing of the reaction media above the beveled substrate 11 and thus facilitate the film formation uniformity. Specifically, the rotation speed can be controlled to be 60 rpm, for example.

[0127] A vacuum system connected to the inside of the reaction chamber is provided outside the reaction chamber of this embodiment to adjust the pressure inside the reaction chamber according to process requirements. In addition, an exhaust device is provided at the bottom of the reaction chamber to discharge the tail gas from the reaction chamber during the process to ensure the pressure inside the reaction chamber.

[0128] In this embodiment, the carrier device 62 can be, for example, a graphite base. The rotating device 63 is a magneto-fluid rotary seal.

[0129] Step S2: Control the bottom heating device 64 so that the temperature inside the reaction chamber is the first temperature, control the vacuum system and the exhaust system so that the pressure inside the reaction chamber is the first pressure, and introduce a gallium source and an oxygen source into the reaction chamber through the injection device 61 to form a first gallium oxide layer on the growth surface. Among them, the gallium source includes trimethylgallium and nitrogen as the carrier gas, the oxygen source is oxygen, the first temperature is 1000 °C, the first pressure is 5 mbar, the flow rate of the gallium source is 30 sccm, the flow rate of the oxygen source is 2000 sccm, the oxygen-containing reaction substance in the oxygen source is oxygen, the gallium-containing reaction substance in the gallium source is trimethylgallium, the molar flow ratio of oxygen to trimethylgallium is controlled to be 2300:1, and the growth time of the first gallium oxide layer 13 is 60 min.

[0130] Step S3: Control the bottom heating device 64 so that the temperature inside the reaction chamber is the second temperature, control the vacuum system and the exhaust system so that the pressure inside the reaction chamber is the second pressure, and then introduce a gallium source and an oxygen source into the reaction chamber through the injection device 61 to form a second gallium oxide layer on the first gallium oxide layer. Among them, the gallium source is trimethylgallium and nitrogen as the carrier gas, the oxygen source is oxygen, the second temperature is 800 °C, the second pressure is 40 mbar, the flow rate of the gallium source is 30 sccm, the flow rate of the oxygen source is 2000 sccm, the molar flow ratio of oxygen to trimethylgallium is controlled to be 2300:1, and the growth time of the second gallium oxide layer 14 is 120 min. In addition, during the process of adjusting the temperature and pressure to reach the second temperature and the second pressure respectively, oxygen is continuously supplied to the reaction chamber through the injection device 61.

[0131] After steps S1 to S3, a gallium oxide thin film is obtained. The surface and cross-sectional morphologies of the thin film are characterized and observed by using an atomic force microscope (AFM). The average thickness of the obtained thin film is 2.5 μm. The crystal quality of the thin film is investigated by using a high-resolution X-ray diffractometer (HRXRD) (as Figure 12 shown). The results show that the surface roughness R of the gallium oxide thin film is 1 nm. The surface morphology picture of the gallium oxide thin film is as Figure 12 shown.

[0132] The full width at half maxima (FWHM) of the X-ray rocking curve (RC) obtained by HRXRD testing reflects the dislocation density of the thin film. The larger the FWHM, the higher the dislocation density of the sample. The RC curve of the thin film in this embodiment is as shown in Figure 13 shown, and its full width at half maximum in the (-2021) direction is 1000 arcseconds.

[0133] Example 2

[0134] This embodiment provides a method for growing a gallium oxide thin film. The gallium oxide thin film is grown using the MOCVD system of Example 1, including steps S1 to S4. The same parts as those in Example 1 will not be described in detail, and the differences are as follows.

[0135] The difference between step S1 and step S1 of Example 1 is that the beveled substrate 11 is a sapphire substrate with a (0001) crystal plane offset by 1° from the (11-20) crystal plane.

[0136] The difference between step S2 and step S2 of Example 1 is as follows: the first temperature is 1100 °C, the first pressure is 10 mbar, the flow rate of the gallium source is 60 sccm, the flow rate of the oxygen source is 2000 sccm, the molar flow ratio of oxygen to trimethylgallium is controlled to be 1150:1, the growth time of the first gallium oxide layer 13 is 10 min, and the rotation speed is controlled to be 100 rpm.

[0137] The difference between step S3 and step S3 of Example 1 is as follows: the second temperature is 900 °C, the second pressure is 60 mbar, the flow rate of the gallium source is 100 sccm, the flow rate of the oxygen source is 5000 sccm, the molar flow ratio of oxygen to trimethylgallium is controlled to be 1800:1, the growth time of the second gallium oxide layer 14 is 20 min, and the rotation speed is controlled to be 100 rpm.

[0138] Step S4: Repeat step S2 and step S3 to complete 10 cycles of the growth process. Completing S2 and S3 is regarded as one cycle of the growth process.

[0139] After steps S1 to S4, a gallium oxide thin film with an average thickness of 10 μm is obtained. The root mean square (RMS) surface roughness of the gallium oxide thin film is 1.5 nm, and the surface topography picture is as shown in Figure 14 shown; the RC curve is as shown in Figure 15 shown, and the full width at half maximum along the (-2021) direction is 800 arcseconds. The specific detection means are as described in Example 1 and will not be elaborated here.

[0140] Example 3

[0141] This embodiment provides a method for growing a gallium oxide thin film. The gallium oxide thin film is grown by using the MOCVD system of Embodiment 1, including steps S1 to S4. The same parts as those in Embodiment 1 will not be described in detail, and the differences are as follows.

[0142] The difference between step S1 and step S1 of Embodiment 1 is that the beveled substrate 11 is a silicon carbide substrate with a (0001) crystal plane deviated from the (1-102) crystal plane by 20°.

[0143] The difference between step S2 and step S2 of Embodiment 1 is that the oxygen source is nitrous oxide, the first temperature is 1200 °C, the first pressure is 20 mbar, the flow rate of the gallium source is 60 sccm, the flow rate of the oxygen source is 2000 sccm, the molar flow rate ratio of nitrous oxide to trimethylgallium is controlled to be 1150:1, the growth time of the first gallium oxide layer 13 is 10 min, and the rotation speed is controlled to be 150 rpm.

[0144] The difference between step S3 and step S3 of Embodiment 1 is that the oxygen source is nitrous oxide, the second temperature is 600 °C, the second pressure is 50 mbar, the flow rate of the gallium source is 100 sccm, the flow rate of the oxygen source is 5000 sccm, the molar flow rate ratio of nitrous oxide to trimethylgallium is controlled to be 1800:1, the growth time of the second gallium oxide layer 14 is 10 min, and the rotation speed is controlled to be 150 rpm.

[0145] Step S4: Repeat the above step S2 and step S3 to complete 20 cycles of the growth process. Completing S2 and S3 is regarded as one cycle of the growth process.

[0146] After steps S1 to S4, a gallium oxide thin film with an average thickness of 15 μm is obtained. The surface roughness RMS of the gallium oxide thin film is 0.8 nm, and the surface topography picture is as Figure 16 shown, and the RC curve is as Figure 17 shown, and the full width at half maximum along the (-2021) direction is 600 arcseconds. The specific detection means are as described in Embodiment 1 and will not be elaborated here.

[0147] Embodiment 4

[0148] This embodiment provides a method for growing a gallium oxide thin film. The gallium oxide thin film is grown by using the MOCVD system of Embodiment 1, including steps S1 to S4. The same parts as those in Embodiment 1 will not be described in detail, and the differences are as follows.

[0149] The difference between step S1 and step S1 of Embodiment 1 is that the beveled substrate 11 is a silicon carbide substrate with a (0001) crystal plane deviated from the (10-10) crystal plane by 5°.

[0150] The difference between step S2 and step S2 of the first embodiment is as follows: the oxygen source is ozone, the first temperature is 1300 °C, the first pressure is 50 mbar, the flow rate of the gallium source is 60 sccm, the flow rate of the oxygen source is 1000 sccm, the molar flow ratio of ozone to trimethylgallium is controlled to be 560:1, the growth time of the first gallium oxide layer 13 is 15 min, and the rotation speed is controlled to be 200 rpm.

[0151] The difference between step S3 and step S3 of the first embodiment is as follows: the oxygen source is ozone, the second temperature is 1000 °C, the second pressure is 100 mbar, the flow rate of the gallium source is 100 sccm, the flow rate of the oxygen source is 3000 sccm, the molar ratio of ozone to trimethylgallium is controlled to be 1050:1, the growth time of the second gallium oxide layer 14 is 15 min, and the rotation speed is controlled to be 200 rpm.

[0152] Step S4: Repeat the above step S2 and step S3 to complete 40 cycles of the growth process. Completing steps S2 and S3 is regarded as one cycle of the growth process.

[0153] After steps S1 to S4, a gallium oxide thin film with an average thickness of 20 μm is obtained. The surface roughness RMS of the gallium oxide thin film is 0.8 nm; the RC curve is as Figure 18 shown, and the full width at half maximum along the (-2021) direction is 200 arcseconds. The specific detection means are as described in the first embodiment and will not be elaborated here.

[0154] Embodiment 5

[0155] This embodiment provides a method for growing a gallium oxide thin film. The gallium oxide thin film is grown by using an HVPE system, including steps S1 to S4, and the specific steps are as follows.

[0156] As Figure 19 shown, the HVPE reaction chamber of the HVPE system includes a first introduction channel 71 and a second introduction channel 72 provided on its side wall, a metal source boat 73 and a carrier base 74 provided inside it, and an exhaust channel 75 provided on its top. The first introduction channel 71 and the second introduction channel 72 are used to introduce gaseous process media (such as an oxygen source, HCL vapor, etc.), the metal source boat 73 is used to place solid process media (such as metallic aluminum, metallic gallium, etc.), the carrier base 74 is used to place the beveled substrate 11, and the exhaust channel 75 is used to discharge the tail gas from the reaction chamber during the process to ensure the pressure inside the reaction chamber.

[0157] The HVPE reaction chamber is also provided with a vacuum control system for controlling the pressure inside the reaction chamber, and a heating device is provided on the chamber wall for heating the substrate carried on the carrier base 74 to the process temperature. The specific implementation method is a conventional technical means in the art.

[0158] Step S1: Provide a reaction chamber and an inclined substrate, and place the inclined substrate in the reaction chamber. The reaction chamber is an HVPE reaction chamber, and the inclined substrate 11 is a silicon substrate with a (11-21) crystal plane deviated from the (11-20) crystal plane by 15°.

[0159] Step S01: Control the temperature in the reaction chamber to be the third temperature, control the pressure in the reaction chamber to be the third pressure, and introduce an aluminum source and an oxygen source into the reaction chamber. Specifically: The metal source boat 73 in the reaction chamber contains metallic aluminum. HCl vapor is introduced through the second inlet channel 72. The HCl vapor flows through the metal source boat 73 and reacts with the molten metallic aluminum contained therein and carries the reaction product stream through the inclined substrate 11 to provide an aluminum source for forming the buffer layer 12 in Step S01. An oxygen source is introduced through the first inlet channel 71, and the oxygen source is transported above the inclined substrate 11, thereby forming an aluminum oxide buffer layer on the inclined substrate 11. Among them, the third temperature is 1000 °C, the third pressure is 10 mbar, the aluminum source includes metallic aluminum and HCl as a carrier gas, the aluminum-containing reaction substance of the aluminum source is metallic aluminum, the oxygen source is oxygen, the flow rate of the aluminum source is 60 sccm, the flow rate of the oxygen source is 600 sccm, the molar flow rate ratio of oxygen to metallic aluminum is 400:1, and the growth time of the buffer layer 12 is 10 min.

[0160] Step S2: Control the temperature in the reaction chamber to be the first temperature, control the pressure in the reaction chamber to be the first pressure, and introduce a gallium source and an oxygen source into the reaction chamber to form a first gallium oxide layer on the buffer layer. Specifically, replace the metallic aluminum in the metal source boat 73 with metallic gallium. The specific process of introducing the gallium source and the oxygen source refers to Step S01 of this embodiment. Among them, the gallium source includes metallic gallium and HCl vapor as a carrier gas, the oxygen source is oxygen, the first temperature is 1100 °C, the first pressure is 5 mbar, the flow rate of the gallium source is 60 sccm, the flow rate of the oxygen source is 600 sccm, the gallium-containing reaction substance of the gallium source is metallic gallium, the oxygen-containing reaction substance of the oxygen source is oxygen, the molar flow rate ratio of oxygen to metallic gallium is 400:1, and the growth time of the first gallium oxide layer 13 is 15 min.

[0161] Step S3: Control the temperature in the reaction chamber to be the second temperature, control the pressure in the reaction chamber to be the second pressure, and introduce a gallium source and an oxygen source into the reaction chamber to form a second gallium oxide layer on the first gallium oxide layer. The specific process of introducing the gallium source and the oxygen source refers to Step S01 of this embodiment. Among them, the gallium source includes metallic gallium and HCl vapor as a carrier gas, the oxygen source is oxygen, the molar flow rate ratio of oxygen to metallic gallium is 400:1, the second temperature is 900 °C, the second pressure is 60 mbar, the flow rate of the gallium source is 100 sccm, the flow rate of the oxygen source is 1000 sccm, and the growth time of the second gallium oxide layer 14 is 10 min.

[0162] Step S4: Repeat the above Step S2 and Step S3 to complete 20 cycles of the growth process. Completion of the execution of S2 and S3 is regarded as one cycle of the growth process.

[0163] After steps S1 to S4, a gallium oxide thin film with an average thickness of 20 μm is obtained. The surface roughness RMS of the gallium oxide thin film is 0.8 nm; the RC curve is as Figure 20 shown, and the full width at half maximum along the (-2021) direction is 200 arcseconds. The specific detection means are as described in Example 1 and will not be elaborated here.

[0164] Example 6

[0165] This example provides a method for growing a gallium oxide thin film. A gallium oxide thin film is deposited using the HVPE system of Example 5, including steps S1 to S4, and the specific steps are as follows.

[0166] The difference between step S1 and step S1 of Example 5 is that the beveled substrate 11 is a silicon substrate with a (11-21) crystal plane deviated by 8° from the (1-102) crystal plane.

[0167] Step S01 is the same as step S01 of Example 5.

[0168] Step S2 is the same as step S2 of Example 5.

[0169] The difference between step S3 and step S3 of Example 5 is that the second temperature is controlled at 800 °C and the growth time is 5 min.

[0170] Step S4 is the same as step S4 of Example 5.

[0171] After steps S1 to S4, a gallium oxide thin film with an average thickness of 10 μm is obtained. The surface roughness RMS of the gallium oxide thin film is 0.8 nm; the RC curve is as Figure 21 shown, and the full width at half maximum along the (-2021) direction is 500 arcseconds.

[0172] The above examples only illustrate the principles and effects of the present application by way of example, and are not intended to limit the present application. Any person familiar with this technology can modify, change or combine the above examples without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present application should still be covered by the claims of the present application.

Claims

1. A method for growing a gallium oxide thin film, characterized in that: The following steps are involved: S1: providing a reaction chamber and a beveled substrate, and placing the beveled substrate in the reaction chamber; S2: After controlling the temperature in the reaction chamber to be a first temperature and the pressure in the reaction chamber to be a first pressure, a gallium source and an oxygen source are introduced into the reaction chamber to form a first gallium oxide layer on the bevel-cut substrate; S3: controlling the temperature in the reaction chamber to be a second temperature, controlling the pressure in the reaction chamber to be a second pressure, and then introducing a gallium source and an oxygen source into the reaction chamber to form a second gallium oxide layer on the first gallium oxide layer; Wherein, the first temperature is 1000° C. to 1300° C., the first pressure is 5 mbar to 50 mbar, the second temperature is 600° C. to 1000° C., and the second pressure is 40 mbar to 100 mbar; The temperature difference between the first temperature and the second temperature does not exceed 600° C., the pressure difference between the second pressure and the first pressure does not exceed 95 mbar, the first temperature is greater than the second temperature, and the first pressure is less than the second pressure; The flow rate of the gallium source introduced in step S3 is not lower than the flow rate of the gallium source introduced in step S2.

2. The method for growing a gallium oxide thin film according to claim 1, characterized in that: The temperature difference between the first temperature and the second temperature is not less than 200° C., and the pressure difference between the second pressure and the first pressure is not less than 5 mbar.

3. The method for growing a gallium oxide thin film according to claim 1, characterized in that: The bevel angle of the beveled substrate is 1° to 20°, and the bevel direction is from the (0001) crystal plane to any one of the (11-20) crystal plane, the (1-102) crystal plane, and the (10-10) crystal plane, or from the (11-21) crystal plane to any one of the (11-20) crystal plane and the (1-102) crystal plane.

4. The method for growing a gallium oxide thin film according to claim 3, characterized in that: The bevel-cut substrate is any one of a sapphire substrate, a silicon carbide substrate or a silicon substrate. The bevel-cut direction of the sapphire substrate is from the (0001) crystal plane to the (11-20) crystal plane, the bevel-cut direction of the silicon carbide substrate is from the (0001) crystal plane to the (1-102) crystal plane or the (10-10) crystal plane, and the bevel-cut direction of the silicon substrate is from the (11-21) crystal plane to the (11-20) crystal plane or the (1-102) crystal plane.

5. The method for growing a gallium oxide thin film according to claim 4, characterized in that: The bevel angle of the sapphire substrate is 1° to 10°; The bevel angle of the silicon carbide substrate is 5° to 15°; The bevel angle of the silicon substrate is 8° to 15°.

6. The method for growing a gallium oxide thin film according to claim 1, characterized in that: The bevel-cut substrate is a silicon substrate. After the step S1 is completed and before the step S2 is performed, the following steps are further performed: controlling the temperature in the reaction chamber to be a third temperature, controlling the pressure in the reaction chamber to be a third pressure, introducing an aluminum source and an oxygen source into the reaction chamber to form a buffer layer on the bevel-cut substrate, wherein the third temperature is higher than the second temperature, and the third pressure is lower than the second pressure; After the buffer layer is formed, step S2 is performed to grow the first gallium oxide layer on the buffer layer.

7. The method for growing a gallium oxide thin film according to claim 6, characterized in that: The temperature difference between the third temperature and the second temperature is 200-600° C., and the pressure difference between the second pressure and the third pressure is 5 mbar-95 mbar.

8. The method for growing a gallium oxide thin film according to claim 6, characterized in that: The third temperature is 1000° C. to 1300° C., and the third pressure is 5 mbar to 50 mbar.

9. The method for growing a gallium oxide thin film according to claim 6, characterized in that: The step of introducing an aluminum source and an oxygen source into the reaction chamber comprises: controlling the flow ratio of the oxygen source to the aluminum source to be 10:1-70:1, and the ratio of the molar flow of the oxygen-containing reaction substance in the oxygen source to the molar flow of the aluminum-containing reaction substance in the aluminum source to be 400:1-1000:

1.

10. The method for growing a gallium oxide thin film according to claim 9, characterized in that: The step of introducing an aluminum source and an oxygen source into the reaction chamber includes: controlling the flow rate of the aluminum source to 30 sccm-60 sccm, controlling the flow rate of the oxygen source to 600 sccm-1000 sccm, and controlling the duration of introducing the oxygen source and the aluminum source to 10 min-60 min.

11. The method for growing a gallium oxide thin film according to claim 6, characterized in that: The aluminum source includes an organic metal compound of aluminum or metallic aluminum, the oxygen source includes an oxygen-containing gas, and the gallium source includes an organic metal compound of gallium or metallic gallium.

12. The method for growing a gallium oxide thin film according to claim 1, characterized in that: In both step S2 and step S3, the flow ratio of the oxygen source to the gallium source is controlled to be 10:1-70:1, and the ratio of the molar flow of the oxygen-containing reaction substance in the oxygen source to the molar flow of the gallium-containing reaction substance in the gallium source is controlled to be 400:1-3000:

1.

13. The method for growing a gallium oxide thin film according to claim 12, characterized in that: In the step S2, the flow rate of the gallium source is controlled to be 30 sccm-60 sccm, the flow rate of the oxygen source is controlled to be 600 sccm-2000 sccm, and the duration of introducing the oxygen source and the gallium source is controlled to be 10 min-60 min.

14. The method for growing a gallium oxide thin film according to claim 12, characterized in that: In the step S3, the flow rate of the gallium source is controlled to be 30 sccm-100 sccm, the flow rate of the oxygen source is controlled to be 1000 sccm-5000 sccm, and the duration of introducing the oxygen source and the gallium source is controlled to be 5 min-120 min.

15. The method for growing a gallium oxide thin film according to claim 1, characterized in that: After executing step S3, the following steps are also included: S4: Repeat the steps S2 and S3 to complete n cycles of growth process, wherein n is a positive integer greater than 1.

16. The method for growing a gallium oxide thin film according to claim 1, characterized in that: The step S3 further includes continuously introducing the oxygen source into the reaction chamber until the temperature in the reaction chamber is controlled to be the second temperature and the pressure in the reaction chamber is controlled to be the second pressure.

17. The method for growing a gallium oxide thin film according to claim 1, characterized in that: The step S2 and the step S3 further include controlling the beveled substrate to rotate around the axis of the reaction chamber at a rate of 20 rpm to 200 rpm.

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