Gallium oxide film growth method

Abstract

The invention belongs to the technical field of semiconductor material preparation, and provides a gallium oxide thin film growth method which comprises the following steps: providing a reaction chamber and a beveled substrate, and placing the beveled substrate in the reaction chamber; after controlling the temperature and the 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 so as to form a first gallium oxide layer on the beveled substrate; after controlling the temperature and the 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 higher than the second temperature, and the first pressure is lower than the second pressure. In the growth process of the first gallium oxide layer and the second gallium oxide layer, the high-temperature and low-pressure growth environment is beneficial to rapid two-dimensional growth of a gallium oxide material, the low-temperature and high-pressure growth environment is beneficial to stress release of the gallium oxide material, defect extension is hindered, dislocation defects are reduced, and the surface quality of a gallium oxide film is improved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor material preparation, and in particular to a method for growing a gallium oxide thin film. Background Art

[0002] Gallium oxide (Ga2O3) is a direct bandgap wide bandgap semiconductor material. It is highly valued in the semiconductor industry due to its large bandgap width and breakdown field strength. Gallium oxide materials have good thermal and chemical stability, and the transmittance in the visible light region can reach more than 80%. At the same time, they have a strong absorption effect on the ultraviolet light region with a wavelength of 200nm~300nm. In terms of 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. The theoretical breakdown field strength can reach 8MV / cm. Based on these excellent properties, gallium oxide materials have important applications in detection, power devices and other fields.

[0003] At present, the gallium oxide thin film used in semiconductor technology is mainly prepared by heteroepitaxial method on substrate. Due to the high decomposition temperature of gallium oxide material, the crystal quality of gallium oxide material is poor and the surface is rough. As the thickness of the film increases, the surface roughness becomes more serious, which seriously affects the yield and reliability of the device, causing the research and development and application of gallium oxide devices to lag seriously.

[0004] Therefore, a new method for growing gallium oxide thin films is urgently needed to solve the above problems existing in the prior art. Summary of the invention

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

[0006] To achieve the above-mentioned purpose, the present application provides a method for growing a gallium oxide thin film, comprising the following steps: 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 not less than 1000°C, and the second temperature is not more than 1000°C; The first pressure is no more than 50 mbar, the second pressure is no less than 20 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.

[0007] 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.

[0008] Optionally, 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.

[0009] 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.

[0010] Optionally, the bevel angle of the beveled substrate is 1°~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 or the (10-10) crystal plane, or from the (11-21) crystal plane to any one of the (11-20) crystal plane or the (1-102) crystal plane.

[0011] Optionally, the beveled substrate is any one of a sapphire substrate, a silicon carbide substrate or a silicon substrate, the beveled direction of the sapphire substrate is from the (0001) crystal plane to the (11-20) crystal plane, the beveled 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 beveled direction of the silicon substrate is from the (11-21) crystal plane to the (11-20) crystal plane or the (1-102) crystal plane.

[0012] Optionally, 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°.

[0013] Optionally, the bevel-cut substrate is a silicon substrate, and 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, and 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.

[0014] 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.

[0015] Optionally, the third temperature is 1000° C. to 1300° C., and the third pressure is 5 mbar to 50 mbar.

[0016] Optionally, the step of introducing an aluminum source and an oxygen source into the reaction chamber includes: controlling the flow ratio of the oxygen source and the aluminum source to be 10:1~70:1, and the ratio of the molar flow rate of the oxygen-containing reaction substance in the oxygen source to the molar flow rate of the aluminum-containing reaction substance in the aluminum source to be 400:1~1000:1.

[0017] Optionally, 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.

[0018] Optionally, 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.

[0019] Optionally, in both step S2 and step S3, the flow ratio of the oxygen source and the gallium source is controlled to be 10:1~70:1, and 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 is controlled to be 400:1~3000:1.

[0020] 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.

[0021] Optionally, in 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 aluminum source is controlled to be 5 min-120 min.

[0022] Optionally, after executing step S3, the following steps are further included: S4: Repeat the steps S2 and S3 to complete n cycles of growth process, wherein n is a positive integer greater than 1.

[0023] Optionally, 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.

[0024] Optionally, 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.

[0025] Compared with the prior art, the gallium oxide thin film growth method provided in the present application has at least the following beneficial effects: The method for growing a gallium oxide film of the present application comprises the following steps: growing a first gallium oxide layer at a first temperature and a first pressure through step S1, growing a second gallium oxide layer at a second temperature and a second pressure through step S2, and controlling the first temperature to be not less than 1000° C., the second temperature to be not more than 1000° C., the first pressure to be not more than 50 mbar, the second pressure to be not less than 20 mbar, and the first temperature to be greater than the second temperature, the first pressure to be less than the second pressure, and the gallium source flow rate introduced in step S3 to be not less than the gallium source flow rate introduced in step S2, so that the process of growing the first gallium oxide layer can facilitate the rapid two-dimensional growth of the gallium oxide material, and the substrate used is a beveled substrate, which can form a multi-step structure, so that the gallium oxide material forms a step flow growth mode on the growth surface, realizes rapid merging, and further forms a flat growth surface; further, the process of growing the second gallium oxide layer can facilitate the stress release of the gallium oxide material, hinder the extension of some defects, reduce dislocation defects, improve the surface quality of the formed gallium oxide film, and further improve the product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram showing a process of growing a gallium oxide thin film provided in an embodiment of the present application is shown.

[0028] Figure 2 Shown is a schematic structural diagram of a substrate provided in an embodiment of the present application.

[0029] Figure 3Shown is a schematic structural diagram of a first gallium oxide layer and a second gallium oxide layer provided in an embodiment of the present application.

[0030] Figure 4 A schematic flow chart showing a method for growing a gallium oxide thin film according to an optional embodiment of the present application is shown.

[0031] Figure 5 Shown is a schematic structural diagram of forming a buffer layer on a substrate provided in an embodiment of the present application.

[0032] Figures 6 to 8 The schematic diagrams respectively show the structures of three different stages in the deposition process of the gallium oxide material provided in the embodiments of the present application on the substrate.

[0033] Fig. 9 and Fig.10 Schematic diagrams of the structures of two different gallium oxide films with stacked structures provided in the embodiments of the present application are shown respectively.

[0034] Fig.11 Shown is a schematic diagram of the structure of the MOCVD system provided in Example 1 of the present application.

[0035] Fig.12 and Fig.13 They respectively show the surface morphology and RC curve schematic diagram of the gallium oxide film prepared in Example 1 of the present application.

[0036] Fig.14 and Fig.15 They respectively show the surface morphology and RC curve schematic diagram of the gallium oxide film prepared in Example 2 of the present application.

[0037] Fig.16 and Fig.17 They respectively show the surface morphology and RC curve schematic diagram of the gallium oxide film prepared in Example 3 of the present application.

[0038] Fig.18 Shown is a schematic diagram of the RC curve of the gallium oxide film prepared in Example 4 of the present application.

[0039] Fig.19 Shown is a schematic diagram of the structure of the HVPE system provided in Example 5 of the present application.

[0040] Fig. 20 Shown is a schematic diagram of the RC curve of the gallium oxide film prepared in Example 5 of the present application.

[0041] Fig.21 Shown is a schematic diagram of the RC curve of the gallium oxide film prepared in Example 6 of the present application.

[0042] Reference numerals: 11. substrate; 12. buffer layer; 13. first gallium oxide layer; 14. second gallium oxide layer; 61. injection device; 62. supporting device; 63. rotating device; 64. heating device; 71. first introduction channel; 72. second introduction channel; 73. metal source boat; 74. supporting base; 75. exhaust channel. DETAILED DESCRIPTION

[0043] In order to make the technical purpose, technical solution and technical effect of the present application clearer, the technical solution in the present application will be clearly and completely described in conjunction with the embodiments below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0045] In the description of the present application, it should be noted that the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the implementation or example are included in at least one implementation or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more implementations or examples in a suitable manner.

[0046] Reference Figure 1 This embodiment provides a method for growing a gallium oxide thin film, including steps S1 to S3, specifically including: Step S1: providing a reaction chamber and a beveled substrate, and placing the beveled substrate in the reaction chamber; Step 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; Step S3: After controlling the temperature in the reaction chamber to be a second temperature and the pressure in the reaction chamber to be a second pressure, a gallium source and an oxygen source are introduced 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.

[0047] Specifically, in steps S1 to S3, the first temperature is not lower than 1000° C., the second temperature is not higher than 1000° C., the first pressure is not higher than 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, so as to improve the efficiency of preparing the gallium oxide film. A substrate is placed in a reaction chamber, the temperature and pressure of the reaction chamber are controlled to be a first temperature and a first pressure respectively, and a gallium source and an oxygen source are introduced 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, the growth surface thereof can have a continuous bevel angle formed by a multi-step structure, so that the gallium oxide material forms a step flow growth mode on the growth surface, and realizes rapid merging between different step surfaces, which is conducive to forming a flat growth surface; and then the temperature and pressure in the reaction chamber are controlled to be a second temperature and a second pressure respectively, and a gallium source and an oxygen source are introduced 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 film; it can be seen that the method can improve the film quality and product yield while taking into account the production efficiency.

[0048] The method for growing a gallium oxide thin film provided in this embodiment will be described in detail below in conjunction with the accompanying drawings. It should be noted that the above sequence does not strictly represent the process sequence of the method for growing a gallium oxide thin film protected by the present application, and those skilled in the art may change it according to the actual processing steps.

[0049] In step S1, the chamfered substrate 11 has an inclined growth surface. Figure 2 A multi-step structure may be formed on the growth surface of the beveled substrate 11 to facilitate the growth of gallium oxide material on the growth surface of the beveled substrate 11 .

[0050] In this embodiment, the beveled substrate 11 may be a sapphire substrate, a silicon carbide substrate, a silicon substrate or a substrate made of other suitable materials, and the inclined growth surface of the beveled substrate 11 may be formed, for example, by processing the upper surface of the horizontally placed beveled substrate 11 to obtain a multi-step structure, thereby forming an inclined growth surface. The specific processing method is a conventional technical means in the art.

[0051] The bevel angle of the beveled substrate 11 is 1° to 20°. For example, the bevel angle of the beveled substrate 11 may be 1°, 5°, 8°, 10°, 15°, 20° or other suitable angles to form an inclined growth surface.

[0052] In an alternative embodiment, reference Figure 2The 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°~20°, and the bevel direction of the beveled substrate 11 is (0001) biased toward any one of the (11-20) crystal plane, the (1-102) crystal plane or the (10-10) crystal plane, or the (11-21) crystal plane biased toward any one of the (11-20) crystal plane or the (1-102) crystal plane.

[0053] In an optional embodiment, the bevel angle is 1° to 10°, and the beveled substrate 11 is, for example, a sapphire substrate whose (0001) crystal plane is offset from the (11-20) crystal plane.

[0054] In an optional embodiment, the bevel angle is 5° to 15°, and the bevel substrate 11 is, for example, a silicon carbide substrate whose (0001) crystal plane is offset from the (10-10) crystal plane or the (1-102) crystal plane.

[0055] In an optional embodiment, the bevel angle is 8° to 15°, and the bevel substrate 11 is, for example, a silicon substrate whose (11-21) crystal plane is offset from the (11-20) crystal plane or the (1-102) crystal plane.

[0056] In step S2, a first gallium oxide layer 13 is formed on the growth surface of the beveled substrate 11. Figure 3 As shown. Specifically, the temperature and pressure of the reaction chamber are controlled to be a first temperature and a 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, wherein the first temperature is not less than 1000°C, and the first pressure is not more than 50 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, thereby providing a favorable two-dimensional growth environment for the first gallium oxide layer 13, so as to achieve rapid growth of the first gallium oxide layer 13.

[0057] In an optional embodiment, the first temperature is 1000°C~1300°C, for example, the first temperature may be 1000°C, 1100°C, 1200°C, 1300°C or other suitable temperatures, and the first pressure is 5mbar~50mbar, for example, the first pressure may be 5mbar, 10mbar, 30mbar, 50mbar or other suitable pressures.

[0058] In step S2 of this embodiment, the gallium source includes an organometallic compound of gallium and / or metallic gallium as a gallium-containing reactant, and the oxygen source includes an oxygen-containing reactant as an oxygen-containing reactant, and the oxygen-containing reactant can be, for example, an oxygen-containing gas, wherein the gallium-containing reactant and the oxygen-containing reactant are substances participating in the reaction of generating a gallium oxide thin film.

[0059] In steps S2 and S3 of some embodiments, the gallium source further includes a carrier gas for carrying gallium-containing reaction substances, such as at least one of argon, nitrogen, hydrogen chloride or other suitable carrier gases.

[0060] In steps S2 and S3 of some embodiments, the oxygen source further includes a carrier gas for carrying oxygen-containing reaction substances, such as at least one of argon gas and nitrogen gas or other suitable carrier gases.

[0061] In step S2 of some embodiments, 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 is controlled to be 400:1 to 3000:1.

[0062] In step S2 of some embodiments, 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 can be controlled to be 400:1 to 2300:1.

[0063] 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 reaction substance in the gallium source is, for example, trimethyl gallium, 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.

[0064] In step S2 of an optional embodiment, the step of introducing a gallium source and an oxygen source into the reaction chamber includes: controlling the flow ratio of the oxygen source to the gallium source to be 10:1 to 70:1.

[0065] In step S2 of an optional embodiment, the duration of introducing the oxygen source and the gallium source is controlled to be 10 min to 60 min.

[0066] In step S2 of the optional embodiment, the flow rate of the gallium source is controlled to be 30sccm~60sccm, and the flow rate of the oxygen source is controlled to be 600sccm~2000sccm; for example, the flow rate of the gallium source can be 30sccm, 40sccm, 50sccm, 60sccm or other suitable values, and the flow rate of the oxygen source is 600sccm, 1000sccm, 1200sccm, 1500sccm, 1800sccm, 2000sccm or other suitable 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, the diffusion of each source gas can be adjusted in combination with the control of the first temperature and the first pressure, and the thickness of the first gallium oxide layer 13 can be regulated to ensure that the film has good surface properties during the gas phase growth reaction.

[0067] In an alternative embodiment, reference Figure 4 After step S1 is completed and before step S2 is executed, the following steps are also included: S01: 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 beveled substrate; wherein the third temperature is higher than the second temperature, and the third pressure is lower than the second pressure.

[0068] In step S01, a buffer layer 12 is formed on the beveled substrate 11. Figure 5 As shown, by growing a buffer layer 12 on the beveled substrate 11, the thermal stress of the beveled substrate 11 can be relieved and film defects can be reduced. The buffer layer serves as a transition layer for growing gallium oxide materials, which can reduce lattice mismatch, improve substrate surface morphology, and promote two-dimensional growth and uniform growth of gallium oxide materials.

[0069] In an optional embodiment, the beveled substrate 11 is a silicon substrate, and step S01 is performed after step S1 is completed and before step S2 is performed. Due to the large difference in lattice constants between silicon and gallium oxide, direct deposition of gallium oxide on silicon is likely to cause significant dislocations and / or stresses at the interface. More importantly, when the gallium oxide material is deposited under the conditions of the first temperature and the first pressure, gallium will easily erode into the silicon substrate, affecting the quality of the film. 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 gallium oxide films.

[0070] In an optional embodiment, the aluminum source includes an organometallic compound of aluminum or metallic aluminum as an aluminum-containing reaction substance, and the oxygen source includes an oxygen-containing reaction substance as an oxygen-containing reaction substance, for example, the oxygen-containing reaction substance is an oxygen-containing gas, wherein the aluminum-containing reaction substance and the oxygen-containing reaction substance are substances participating in the reaction during the generation of the buffer layer. The aluminum-containing reaction substance in the aluminum source is, for example, trimethyl aluminum, metallic aluminum or other suitable substances, and the oxygen-containing reaction substance 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.

[0071] In step S01 of some embodiments, the aluminum source further includes a carrier gas for carrying aluminum-containing reaction substances, such as at least one of argon, nitrogen, and hydrogen chloride.

[0072] In step S01 of some embodiments, the oxygen source further includes a carrier gas for carrying oxygen-containing reaction substances, such as at least one of argon and nitrogen.

[0073] In an optional embodiment, the third temperature is 1000°C~1300°C, and the third pressure is 5mbar~50mbar. 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, 5mbar, 10mbar, 20mbar, 30mbar, 40mbar, 50mbar or other suitable values.

[0074] In an optional embodiment, the third pressure is, for example, 5 mbar-10 mbar.

[0075] In an optional 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.

[0076] In an optional 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.

[0077] In an optional embodiment, the pressure difference between the second pressure and the third pressure may be controlled not to exceed 55 mbar.

[0078] 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, wherein the flow rate ratio of the oxygen source to the aluminum source can be understood as a volume flow rate ratio.

[0079] In step S01 of an optional embodiment, the duration of introducing the oxygen source and the aluminum source is controlled to be 10 min to 60 min.

[0080] In step S01 of an optional embodiment, the step of controlling the flow rate ratio of the oxygen source to the aluminum source to be 10:1-70:1 includes: controlling the flow rate of the aluminum source to be 30 sccm-60 sccm; the flow rate of the aluminum source may 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-1000 sccm. The flow rate of the oxygen source may be, for example, 600 sccm, 700 sccm, 800 sccm, 900 sccm, 1000 sccm or other suitable values.

[0081] In step S01 of an optional embodiment, the ratio of the molar flow rate of the oxygen-containing reaction substance in the oxygen source to the molar flow rate of the aluminum-containing reaction substance in the aluminum source is 400:1-1000:1.

[0082] In this embodiment, the buffer layer 12, the first gallium oxide layer 13 and the second gallium oxide layer 14 may be grown by atomic layer deposition (ALD), metal organic chemical vapor deposition (MOCVD), pulsed laser deposition (PLD), hydride vapor phase deposition (HVPE), molecular beam epitaxy (MBE) or other suitable methods.

[0083] In the prior art, due to the complicated growth process, high cost, poor mechanical strength and conductivity of gallium oxide single crystal substrates, which cannot meet the application of some semiconductor devices, a foreign substrate is usually used for the vapor phase growth of gallium oxide. However, due to the large difference in thermal expansion coefficient between the foreign substrate and the gallium oxide material, there is also a large lattice mismatch between the two, and the vapor phase growth reaction is prone to produce a high dislocation density, which in turn has an adverse effect on the surface properties of the gallium oxide layer, such as roughness.

[0084] The present application adopts a beveled substrate 11, which can form a multi-level step structure on its growth surface. Combined with the first temperature and the first pressure control of step S2, the obtained gallium oxide material is deposited at the step of the growth surface, and gradually grows and extends in the two-dimensional direction at the step. Then, the film layers deposited at each step gradually merge, and then transform 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, refer to Figures 6 to 8 In the early stage of gallium oxide growth, it is deposited on each step. Adjacent atomic steps will merge into a micro step, and the steps will continue to merge in the subsequent growth process to form a macro step on the surface of the film layer. When the film layer on the high step merges with the film layer on the low step, some dislocations of the film layer on the low step (dislocations growing in the vertical direction) will be blocked by the lateral growth of the film layer on the high step and terminated, thereby reducing the dislocation density of the film.

[0085] 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 attach to the edge of the step during the film deposition process, making it difficult to merge the steps, and it is easy to change from a two-dimensional layered growth mode to a three-dimensional island growth mode, resulting in poor uniformity of the film. When the bevel angle of the beveled substrate 11 is too small, the step flow growth mode will be limited, resulting in an increase in defects such as dislocations in the film.

[0086] In step S3 of this embodiment, a second gallium oxide layer 14 is grown on the first gallium oxide layer 13. Figure 3As shown, the working conditions in the reaction chamber are suitable for the growth environment of the second gallium oxide layer 14, the temperature and pressure of the reaction chamber are controlled to be the second temperature and the second pressure respectively, and the second temperature is lower than the first temperature, and the second pressure is higher than the first pressure, and the gallium source flow rate introduced in step S3 is controlled not lower than the gallium source flow rate introduced in step S2, so that the reaction chamber has an environment suitable for the growth of the second gallium oxide layer 14, and the growth rate of the second gallium oxide layer 14 is not lower than the growth rate of the first gallium oxide layer 13, wherein the second temperature does not exceed 1000°C, and the second pressure is not lower than 20 mbar. The growth conditions of the second temperature and the second pressure facilitate 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 film, and thus improve the product yield.

[0087] In an optional embodiment, the second pressure may also be controlled to be no less than 40 mbar.

[0088] In an optional embodiment, the second temperature is 600°C~1000°C, for example, the second temperature may be 600°C, 700°C, 800°C, 900°C, 1000°C or other suitable temperatures, and the second pressure is 40mbar~100mbar, for example, the second pressure may be 40mbar, 50mbar, 60mbar, 80mbar, 90mbar, 100mbar or other suitable pressures.

[0089] In an optional 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 less than 200°C, and the pressure difference between the second pressure and the first pressure is not less than 5 mbar.

[0090] In an optional embodiment, the pressure difference between the second pressure and the first pressure may also be controlled to be no more than 55 mbar.

[0091] In step S2, the first gallium oxide layer 13 is controlled to grow at a first temperature and a first pressure, and in step S3, the second gallium oxide layer 14 is controlled to grow 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 the migration rate of gallium on the surface to be within a suitable range. Combined with low-pressure control, the gas phase reaction rate can be properly controlled, which is conducive 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 reaction will aggravate the difference in thermal expansion coefficient and lattice mismatch between the heterogeneous substrate and the film, low-pressure control is not conducive to the compactness of the film, and therefore, in step S3, gallium oxide growth is performed at a second temperature and a second pressure, and the temperature difference between the first temperature and the second temperature and the pressure difference between the second pressure and the first pressure are controlled within a suitable range. The thermal stress is released by cooling and high-pressure control in step S3, and the film is compacted and the stress distribution is adjusted to be uniform.

[0092] In step S3 of this embodiment, the gallium source includes an organometallic compound of gallium and / or metallic gallium as a gallium-containing reaction substance, the oxygen source includes an oxygen-containing reaction substance as an oxygen-containing reaction substance, and the oxygen-containing reaction substance may be, for example, an oxygen-containing gas, and 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 second gallium oxide layer 14 may be set according to actual needs. The gallium-containing reaction substance in the gallium source may be, for example, trimethyl gallium, metallic gallium, or other suitable substances, and the oxygen-containing reaction substance in the oxygen source may be, for example, nitrous oxide, oxygen, ozone, or other suitable substances.

[0093] In step S3 of an optional embodiment, the step of introducing a gallium source and an oxygen source into the reaction chamber includes: controlling the flow ratio of the oxygen source to the gallium source to be 10:1 to 70:1.

[0094] In step S3 of an optional embodiment, 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 is controlled to be 400:1-3000:1.

[0095] In step S3 of an optional embodiment, 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 may be controlled to be 400:1-2300:1.

[0096] In step S3 of an optional embodiment, the duration of introducing the oxygen source and the aluminum source is controlled to be 5 min to 120 min.

[0097] In step S3 of an optional embodiment, the step of controlling the flow ratio of the oxygen source and the gallium source to be 10:1~70:1 includes: controlling the flow rate of the gallium source to be 30sccm~100sccm, and controlling the flow rate of the oxygen source to be 1000sccm~5000sccm; for example, the flow rate of the gallium source can be 30sccm, 40sccm, 50sccm, 60sccm, 80sccm, 90sccm, 100sccm or other suitable values, and the flow rate of the oxygen source is 1000sccm, 2000sccm, 2400sccm, 3000sccm, 4000sccm, 4500sccm, 4800sccm, 5000sccm or other suitable values.

[0098] In step S3 of the optional embodiment, the flow rate of the introduced gallium source is controlled to be no lower than the flow rate of the introduced gallium source in step S2, so as to increase the growth rate and improve the process efficiency.

[0099] In an alternative embodiment, reference Figure 4 After step S3 is completed, the following steps may also be included: S4: Repeat the steps S2 and S3 to complete n cycles of growth process, wherein n is a positive integer greater than 1.

[0100] In step 4, completing steps S2 and S3 once is considered as one cycle growth process. Fig. 9 and Fig.10 The prepared gallium oxide film is a stacked structure, including a plurality of first gallium oxide layers 13 and second gallium oxide layers 14 that are alternately stacked in sequence. Optionally, the gallium oxide film can be, for example, a 4-layer stacked structure, including two first gallium oxide layers 13 and two second gallium oxide layers 14, and the first gallium oxide layers 13 and the second gallium oxide layers 14 are alternately stacked in sequence. The gallium oxide film can also be a 10-layer stacked structure, a 20-layer stacked structure, a 40-layer stacked structure, or a stacked structure with other suitable numbers of layers. The specific value of n can be set according to actual needs.

[0101] Through the above-mentioned cyclic growth process, a gallium oxide film with a stacked 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, the process is switched to release the thermal stress through step S3 in time, so that a gallium oxide film with a designed thickness, good surface properties and low dislocation density can be prepared.

[0102] In step S2 and step S3 of the optional embodiment, the beveled substrate is further controlled 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 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 suitable rotation speeds.

[0103] In an 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 controlled to be a second pressure.

[0104] The method for growing a gallium oxide thin film provided by the present application will be further described below in conjunction with some specific embodiments.

[0105] Embodiment 1

[0106] This embodiment provides a method for growing a gallium oxide thin film, which uses an MOCVD system to grow the gallium oxide thin film, including steps S1 to S3. The specific steps are as follows.

[0107] Step S1: providing a reaction chamber and a bevel-cut substrate, placing the bevel-cut substrate in the reaction chamber, the reaction chamber being an MOCVD reaction chamber, and the bevel-cut substrate 11 being a sapphire substrate with a (0001) crystal plane offset by 10° from the (11-20) crystal plane.

[0108] Specifically, the reaction chamber structure is as follows Fig.11 As shown, it includes an injection device 61, a carrier device 62, a rotating device 63 and a heating device 64. The injection device 61 is located at the top of the reaction chamber. The injection device 61 and the carrier device 62 are arranged opposite to each other along the axial direction of the reaction chamber and are located above the carrier device 62. A sheet groove (not shown in the figure) is provided on the top surface of the carrier device 62, and a beveled substrate 11 (not shown in the figure) is accommodated in the sheet groove (not shown 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) to the top surface of the carrier device 62 according to the process requirements. The heating device 64 is located at the bottom of the reaction chamber and below the carrier device 62. The heating device 64 provides heat to the carrier device 62 and transfers heat to the beveled substrate 11 to achieve the reaction temperature required by the process.

[0109] In this embodiment, the carrier 62 is driven by the rotating device 63 to rotate around the axis of the reaction chamber during the process to facilitate uniform mixing of the reaction medium above the beveled substrate 11 and facilitate uniform film formation. Specifically, the rotation speed can be controlled to 60 rpm, for example.

[0110] The reaction chamber of this embodiment is also provided with a vacuum system connected to the reaction chamber to adjust the pressure in the reaction chamber according to the process requirements. In addition, the bottom of the reaction chamber is also provided with an exhaust device to discharge the tail gas from the reaction chamber during the process to ensure the pressure in the reaction chamber.

[0111] In this embodiment, the bearing device 62 may be, for example, a graphite base. The rotating device 63 is a magnetic fluid rotating seal.

[0112] Step S2: Control the bottom heating device 64 so that the temperature in the reaction chamber is the first temperature, control the vacuum system and the exhaust system so that the pressure in 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. The gallium source includes trimethyl gallium and nitrogen as a 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 trimethyl gallium, the molar flow ratio of oxygen to trimethyl gallium is controlled to be 2300:1, and the growth time of the first gallium oxide layer 13 is 60 minutes.

[0113] Step S3: After controlling the bottom heating device 64 so that the temperature in the reaction chamber is the second temperature, and controlling the vacuum system and the exhaust system so that the pressure in the reaction chamber is the second pressure, a gallium source and an oxygen source are introduced 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 trimethyl gallium and nitrogen as a carrier gas, the oxygen source is oxygen, the second temperature is 800°C, the second pressure is 40mbar, the flow rate of the gallium source is 30sccm, the flow rate of the oxygen source is 2000sccm, the molar flow ratio of oxygen to trimethyl gallium is controlled to be 2300:1, and the growth time of the second gallium oxide layer 14 is 120min. In addition, in 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.

[0114] After step S1 to step S3, a gallium oxide film is obtained. The surface and cross-sectional morphology of the film are characterized and observed using an atomic force microscope (AFM). The average thickness of the obtained film is 2.5 μm. A high resolution X-ray diffraction (HRXRD) is used to examine the crystal quality of the film (such as Fig.12 As shown in the figure, the surface roughness R of the gallium oxide film is 1 nm. The surface morphology of the gallium oxide film is shown in the figure Fig.12 shown.

[0115] The full width at half maximum (FWHM) of the X-ray rocking curve (RC) obtained by HRXRD test reflects the dislocation density of the film. The larger the FWHM, the higher the dislocation density of the sample. The RC curve of the film in this embodiment is as follows: Fig.13 As shown, its half-width in the (-2021) direction is 1000 arc seconds.

[0116] Embodiment 2

[0117] This embodiment provides a method for growing a gallium oxide thin film, which uses the MOCVD system of the first embodiment to grow a gallium oxide thin film, including steps S1 to S4, and the same points as the first embodiment are not repeated here, and the differences are as follows.

[0118] The difference between step S1 and step S1 of the first embodiment is that the beveled substrate 11 is a sapphire substrate whose (0001) crystal plane is 1° offset from the (11-20) crystal plane.

[0119] The difference between step S2 and step S2 of embodiment 1 is that 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.

[0120] The difference between step S3 and step S3 of embodiment 1 is that 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.

[0121] Step S4: Repeat the steps S2 and S3 to complete 10 cycles of growth process. The completion of S2 and S3 is regarded as one cycle of growth process.

[0122] After step S1 to step S4, a gallium oxide film with an average thickness of 10 μm is obtained. The surface roughness RMS of the gallium oxide film is 1.5 nm. The surface morphology picture is as follows: Fig.14 As shown; RC curve is as Fig.15 As shown, the half-height width along the (-2021) direction is 800 arc seconds. The specific detection means is as described in the first embodiment and will not be described in detail here.

[0123] Embodiment 3

[0124] This embodiment provides a method for growing a gallium oxide thin film, which uses the MOCVD system of the first embodiment to grow a gallium oxide thin film, including steps S1 to S4. The same points as the first embodiment are not repeated here, and the differences are as follows.

[0125] The difference between step S1 and step S1 of the first embodiment is that the beveled substrate 11 is a silicon carbide substrate whose (0001) crystal plane is offset by 20° from the (1-102) crystal plane.

[0126] 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 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.

[0127] 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 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.

[0128] Step S4: Repeat the steps S2 and S3 to complete 20 cycles of growth process. The completion of S2 and S3 is regarded as one cycle of growth process.

[0129] After step S1 to step S4, a gallium oxide film with an average thickness of 15 μm is obtained. The surface roughness RMS of the gallium oxide film is 0.8 nm. The surface morphology picture is as follows: Fig.16 As shown, the RC curve is Fig.17 As shown, the half-maximum width along the (-2021) direction is 600 arc seconds. The specific detection means is as described in the first embodiment and will not be described in detail here.

[0130] Embodiment 4

[0131] This embodiment provides a method for growing a gallium oxide thin film, which uses the MOCVD system of the first embodiment to grow a gallium oxide thin film, including steps S1 to S4. The same points as the first embodiment are not repeated here, and the differences are as follows.

[0132] The difference between step S1 and step S1 of the first embodiment is that the beveled substrate 11 is a silicon carbide substrate whose (0001) crystal plane is 5° offset from the (10-10) crystal plane.

[0133] The difference between step S2 and step S2 of embodiment 1 is that 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.

[0134] The difference between step S3 and step S3 of embodiment 1 is that 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.

[0135] Step S4: Repeat the steps S2 and S3 to complete 40 cycles of growth process. The completion of S2 and S3 is regarded as one cycle of growth process.

[0136] After step S1 to step S4, a gallium oxide film with an average thickness of 20 μm is obtained, and the surface roughness RMS of the gallium oxide film is 0.8 nm; the RC curve is as follows: Fig.18 As shown, the half-height width along the (-2021) direction is 200 arc seconds. The specific detection means is as described in the first embodiment and will not be described in detail here.

[0137] Embodiment 5

[0138] This embodiment provides a method for growing a gallium oxide thin film, which uses an HVPE system to grow the gallium oxide thin film, including steps S1 to S4, and the specific steps are as follows.

[0139] like Fig.19 As shown, the HVPE reaction chamber of the HVPE system includes a first inlet channel 71 and a second inlet channel 72 arranged on its side wall, a metal source boat 73 and a supporting base 74 arranged inside it, and an exhaust channel 75 arranged on its top. The first inlet channel 71 and the second inlet channel 72 are used to introduce gaseous process media (such as oxygen source, HCL vapor, etc.), the metal source boat 73 is used to place solid process media (such as metal aluminum, metal gallium, etc.), the supporting base 74 is used to place the bevel-cut substrate 11, and the exhaust channel 75 is used to exhaust the tail gas from the reaction chamber during the process to ensure the pressure in the reaction chamber.

[0140] The HVPE reaction chamber is also provided with a vacuum control system for controlling the pressure in the reaction chamber, and a heating device is provided on the chamber wall for making the substrate carried on the carrying base 74 reach the process temperature. The specific implementation method is conventional technical means in this field.

[0141] Step S1: providing a reaction chamber and a bevel-cut substrate, and placing the bevel-cut substrate in the reaction chamber, wherein the reaction chamber is a HVPE reaction chamber, and the bevel-cut substrate 11 is a silicon substrate whose (11-21) crystal plane deviates 15° from the (11-20) crystal plane.

[0142] 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, introduce an aluminum source and an oxygen source into the reaction chamber, specifically: the metal source boat 73 of the reaction chamber contains metal aluminum, introduce HCl vapor through the second introduction channel 72, the HCl vapor flows through the metal source boat 73 to react with the molten metal aluminum contained therein and carries the reaction product to flow through the bevel-cut substrate 11, so as to provide an aluminum source for forming a buffer layer 12 in step S01, introduce an oxygen source through the first introduction channel 71, and transmit the oxygen source to the top of the bevel-cut substrate 11, thereby forming an aluminum oxide buffer layer on the bevel-cut substrate 11. Wherein, the third temperature is 1000° C., the third pressure is 10 mbar, the aluminum source includes metal aluminum and HCl as a carrier gas, the aluminum-containing reaction substance of the aluminum source is metal 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 metal aluminum is 400:1, and the growth time of the buffer layer 12 is 10 minutes.

[0143] 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 metal aluminum in the metal source boat 73 with metal gallium, and refer to step S01 of this embodiment for the specific process of introducing the gallium source and the oxygen source. Among them, the gallium source includes metal gallium and HCl vapor as a carrier gas, the oxygen source is oxygen, the first temperature is 1100°C, the first pressure is 5mbar, the flow rate of the gallium source is 60sccm, the flow rate of the oxygen source is 600sccm, the gallium-containing reaction substance of the gallium source is metal gallium, the oxygen-containing reaction substance of the oxygen source is oxygen, the molar flow ratio of oxygen to metal gallium is 400:1, and the growth time of the first gallium oxide layer 13 is 15min.

[0144] 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 is referred to step S01 of this embodiment. The gallium source includes metal gallium and HCl vapor as a carrier gas, the oxygen source is oxygen, the molar flow ratio of oxygen to metal gallium is 400:1, the second temperature is 900°C, the second pressure is 60mbar, the flow rate of the gallium source is 100sccm, the flow rate of the oxygen source is 1000sccm, and the growth time of the second gallium oxide layer 14 is 10min.

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

[0146] After step S1 to step S4, a gallium oxide film with an average thickness of 20 μm is obtained, and the surface roughness RMS of the gallium oxide film is 0.8 nm; the RC curve is as follows: Fig. 20 As shown, the half-height width along the (-2021) direction is 200 arc seconds. The specific detection means is as described in the first embodiment and will not be described in detail here.

[0147] Embodiment 6

[0148] This embodiment provides a method for growing a gallium oxide thin film, which uses the HVPE system of the fifth embodiment to deposit the gallium oxide thin film, including steps S1 to S4, and the specific steps are as follows.

[0149] The difference between step S1 and step S1 of the fifth embodiment is that the beveled substrate 11 is a silicon substrate whose (11-21) crystal plane is 8° offset from the (1-102) crystal plane.

[0150] Step S01 is consistent with step S01 in the fifth embodiment.

[0151] Step S2 is consistent with step S2 in the fifth embodiment.

[0152] The difference between step S3 and step S3 of embodiment 5 is that the second temperature is controlled to be 800° C. and the growth time is 5 min.

[0153] Step S4 is consistent with step S4 in the fifth embodiment.

[0154] After step S1 to step S4, a gallium oxide film with an average thickness of 10 μm is obtained, and the surface roughness RMS of the gallium oxide film is 0.8 nm; the RC curve is as follows: Fig.21 As shown, the half-width along the (-2021) direction is 500 arc seconds.

[0155] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify, change or combine the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall 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 not less than 1000°C, and the second temperature is not more than 1000°C; The first pressure is no more than 50 mbar, the second pressure is no less than 20 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 does not exceed 600° C., and the pressure difference between the second pressure and the first pressure does not exceed 95 mbar.

3. The method for growing a gallium oxide thin film according to claim 2, 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.

4. The method for growing a gallium oxide thin film according to claim 1, characterized in that: 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.

5. 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.

6. The method for growing a gallium oxide thin film according to claim 5, 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.

7. The method for growing a gallium oxide thin film according to claim 6, wherein: 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°.

8. 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.

9. The method for growing a gallium oxide thin film according to claim 8, 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.

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

11. The method for growing a gallium oxide thin film according to claim 8, 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.

12. The method for growing a gallium oxide thin film according to claim 11, 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.

13. The method for growing a gallium oxide thin film according to claim 8, 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.

14. 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.

15. The method for growing a gallium oxide thin film according to claim 14, 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.

16. The method for growing a gallium oxide thin film according to claim 14, 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 aluminum source is controlled to be 5 min-120 min.

17. 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.

18. 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.

19. 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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