Preparation method of gallium nitride single crystal wafer

Abstract

The invention relates to the technical field of semiconductor material preparation, in particular to a gallium nitride single crystal wafer material preparation method which comprises the following steps: placing a silicon carbide substrate slice larger than a standard size in an accommodating groove of a graphite tray, and installing a cylindrical silicon nitride ceramic protective cover to assemble a substrate tray; putting the substrate tray into a magnetron sputtering growth chamber to prepare a zinc-aluminum-oxygen polycrystalline thin film and an aluminum nitride polycrystalline thin film in sequence; the substrate tray is placed in a high-temperature and high-vacuum annealing furnace chamber for high-temperature and high-vacuum annealing treatment, and the substrate tray is placed in a hydride vapor phase epitaxy reaction chamber for preparing the gallium nitride single crystal thick film material; cutting, grinding and polishing the peeled gallium nitride single crystal thick film wafer with the size larger than the standard size to obtain a gallium nitride single crystal wafer material with the standard size; and the stripped silicon carbide substrate slice and the used cylindrical silicon nitride ceramic protective cover can be repeatedly used after being cleaned. According to the method, low-stress, low-dislocation-density, low-cost and high-yield preparation of the standard-size gallium nitride single crystal wafer material can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor material preparation, and particularly relates to a method for preparing a gallium nitride single crystal wafer. Background Art

[0002] Using the hydride vapor phase epitaxy process to epitaxially grow gallium nitride single crystal material on a hetero-substrate wafer. In the prior art, a graphite tray coated with a silicon carbide protective coating is used as the substrate tray. First, the substrate wafer is placed in the accommodation groove at the top of the graphite tray to carry the substrate wafer, and then the graphite tray loaded with the substrate wafer is installed on the rotating base of the reaction chamber of the hydride vapor phase epitaxy equipment. After rapidly preparing a gallium nitride single crystal thick film by the hydride vapor phase epitaxy process, the graphite tray is taken out after cooling, and the gallium nitride single crystal thick film material is peeled off from the substrate wafer. Since the gap between the substrate wafer and the accommodation groove of the graphite tray is filled with deposited gallium nitride material, it is not only inconvenient to clean the graphite tray, but also inconvenient to take out the prepared gallium nitride single crystal thick film material. If the gap between the substrate wafer and the accommodation groove of the graphite tray is completely blocked, inevitably, a part of the substrate wafer will be blocked, and the diameter of the gallium nitride single crystal thick film prepared using a standard-sized substrate wafer is smaller than the standard size. Then, after cutting, grinding, and polishing the self-supporting gallium nitride single crystal thick film wafer peeled off, the outer diameter of the obtained gallium nitride single crystal wafer material will also be smaller than the standard size. Using it as a homo-substrate to develop and produce gallium nitride-based devices will not only affect the subsequent manufacturing process of gallium nitride devices, but also reduce the number of gallium nitride device productions, thereby resulting in high device production costs and low yields. Summary of the Invention

[0003] The present invention provides a method for preparing a gallium nitride single crystal wafer to solve the problem that the outer diameters of the gallium nitride single crystal thick film prepared using a standard-sized substrate wafer and the gallium nitride single crystal wafer material obtained by subsequent cutting, grinding, and polishing are smaller than the standard size due to the need to block the gap between the substrate wafer and the accommodation groove of the graphite tray, and using it to manufacture devices will result in high device production costs and low yields.

[0004] The present invention provides a method for preparing a gallium nitride single crystal wafer, including the following steps: S1: Place a silicon carbide substrate wafer larger than the standard size in the accommodation groove of the graphite tray, install a cylindrical silicon nitride ceramic protective cover on the graphite tray, and assemble to obtain a substrate tray; S2: Invert and install the substrate tray in step S1 on the rotating base of the growth chamber of the magnetron sputtering equipment, and sequentially prepare a zinc aluminum oxide polycrystalline thin film and an aluminum nitride polycrystalline thin film on the silicon carbide substrate wafer larger than the standard size; S3: After taking out the substrate tray in step S2 and cooling it, place it in the high-temperature and high-vacuum annealing furnace chamber for high-temperature and high-vacuum annealing treatment, convert the zinc aluminum oxide polycrystalline thin film into a porous alumina weakly bonded decoupling layer, and convert the aluminum nitride polycrystalline thin film into an aluminum nitride single crystal template layer; S4: After cooling down and taking out the substrate tray in S3, it is inversely installed on the substrate rotating base in the reaction chamber of the hydride vapor phase epitaxy equipment, and a gallium nitride single crystal thick film is deposited on the aluminum nitride single crystal template layer by using the hydride vapor phase epitaxy process; S5: Cool down and take out the substrate tray in S4, remove the cylindrical silicon nitride ceramic protective cover, and peel off from the silicon carbide substrate wafer larger than the standard size to obtain a gallium nitride single crystal thick film wafer larger than the standard size; S6: Grind and polish the gallium nitride single crystal thick film wafer larger than the standard size to obtain a gallium nitride single crystal wafer material of standard size; S7: Perform high-temperature and high-vacuum baking and cleaning on the silicon carbide substrate wafer and the silicon nitride ceramic protective cover larger than the standard size under a chlorine atmosphere; S8: Repeat steps S1 to S7.

[0005] In some embodiments, in step S1, a deposition window is opened on the cylindrical silicon nitride ceramic protective cover, and the cylindrical silicon nitride ceramic protective cover is flexibly connected to the graphite tray.

[0006] In some embodiments, in step S2, when preparing the zinc aluminum oxide polycrystalline thin film, argon is used as the sputtering gas and oxygen is used as the reaction gas, and a zinc aluminum oxide polycrystalline thin film with a thickness of 10 - 50 nm and an aluminum content of 20 - 80% is prepared by using a reactive co-sputtering process with a metal zinc target and a metal aluminum target.

[0007] In some embodiments, in step S2, when preparing the aluminum nitride polycrystalline thin film, argon is used as the sputtering gas and nitrogen is used as the reaction gas, and an aluminum nitride polycrystalline thin film with a thickness of 100 - 1000 nm is prepared by using a reactive sputtering process with a metal aluminum target.

[0008] In some embodiments, in step S3, the high-temperature and high-vacuum annealing treatment is: heating to 1400 - 1600 °C under a hydrogen atmosphere and holding for 5 - 10 hours under a vacuum state.

[0009] In some embodiments, in step S3, the dislocation density of the aluminum nitride single crystal template layer is lower than 5×10 7 cm -2 .

[0010] In some embodiments, in step S4, the thickness of the gallium nitride single crystal thick film is 300 - 2000 µm.

[0011] In some embodiments, in step S6, the dislocation density of the gallium nitride single crystal wafer of standard size is lower than or equal to 1×10 6 cm -2 .

[0012] In some of these embodiments, in step S1, the sizes of the standard-sized silicon carbide substrate wafers include, but are not limited to, 2, 4, 6, 8, and 12 inches.

[0013] In some of these embodiments, the sizes of the standard-sized gallium nitride single-crystal wafer materials include, but are not limited to, 2, 4, 6, 8, and 12 inches.

[0014] The beneficial effects of the present invention are as follows: The method for preparing a gallium nitride single-crystal wafer provided in this application uses a silicon carbide substrate wafer larger than the standard size, a cylindrical silicon nitride ceramic protective cover, and introduces a suitable weakly bonded decoupling layer, which can prepare a standard-sized gallium nitride single-crystal wafer, facilitating subsequent homoepitaxial preparation of gallium nitride devices on the gallium nitride single-crystal wafer, and enabling the reuse of non-standard-sized silicon carbide substrate wafers, reducing the preparation cost of standard-sized gallium nitride single-crystal wafer materials, and improving the yield of gallium nitride single-crystal wafers. Description of the Drawings

[0015] Figure 1 is a schematic flow chart of a method for preparing a gallium nitride single-crystal wafer according to this application; Figure 2 is a schematic structural diagram of a graphite tray equipped with a cylindrical silicon nitride ceramic protective cover; Figure 3 is Figure 2 a schematic structural diagram of the flexible connecting member in

[0016] In the drawings, 1. graphite tray; 11. receiving groove; 12. positioning hole; 13. graphite base; 2. cylindrical silicon nitride ceramic protective cover; 21. deposition window; 22. mounting hole; 3. substrate wafer; 4. gallium nitride single-crystal thick film; 5. flexible connecting member; 51. positioning bolt; 52. fastening bolt; 53. ceramic spring; 6. porous alumina weakly bonded decoupling layer; 7. aluminum nitride single-crystal template layer; 8. rotating base; 9. screw. Detailed Embodiments

[0017] The technical solutions of the present invention 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 invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] In the embodiments of the present invention, a variety of high-purity substances will be used. Among them, the purity of zinc element in the high-purity metal zinc target is greater than 99.99%; the purity of aluminum element in the high-purity metal aluminum target is greater than 99.99%; the purity of gallium element in the high-purity metal gallium is greater than 99.99%; the purity of nitrogen element in the high-purity nitrogen is greater than 99.9999%; the purity of argon element in the high-purity argon is greater than 99.999%; the purity of hydrogen element in the high-purity hydrogen is greater than 99.9999%; the purity of hydrogen chloride in the high-purity hydrogen chloride gas is greater than 99.9999%.

[0019] As described in the background art, after the gap between the shielding substrate sheet and the graphite tray receiving groove is blocked, the outer diameter of the gallium nitride single crystal thick film prepared using a standard-sized substrate is smaller than the standard size. Then, using it to manufacture devices results in high production costs and low yield. Therefore, how to prepare a gallium nitride single crystal thick film of standard size, reduce production costs, and improve the yield has become a technical problem that needs to be urgently solved by those skilled in the art.

[0020] To solve the above problems, referring to Figure 1 、 Figure 2 and Figure 3 , this application provides a method for preparing a gallium nitride single crystal wafer, including the following steps: S1: Place a silicon carbide substrate sheet 3 larger than the standard size in the receiving groove 11 of the graphite tray 1, and install a cylindrical silicon nitride ceramic protective cover 2 on the graphite tray 1 to assemble a substrate tray; S2: Invert and install the substrate tray in S1 on the rotating base 8 of the growth chamber of the magnetron sputtering device, and sequentially deposit a zinc aluminum oxide polycrystalline thin film and an aluminum nitride polycrystalline thin film on the silicon carbide substrate sheet 3 larger than the standard size; S3: After cooling the substrate tray in S2, take it out and then put it into the high-temperature and high-vacuum annealing furnace chamber for high-temperature and high-vacuum annealing treatment. The zinc aluminum oxide polycrystalline thin film is converted into a porous alumina weakly bonded decoupling layer 6, and the aluminum nitride polycrystalline thin film is transformed into an aluminum nitride single crystal template layer 7; S4: After cooling and taking out the substrate tray in S3, invert and install it on the substrate rotating base 8 in the reaction chamber of the hydride vapor phase epitaxy device, and deposit a gallium nitride single crystal thick film 4 on the aluminum nitride single crystal template layer 7 using the hydride vapor phase epitaxy process; S5: After cooling and taking out the substrate tray in S4, remove the cylindrical silicon nitride ceramic protective cover 2, and peel off the gallium nitride single crystal thick film 4 from the silicon carbide substrate sheet 3 to obtain a gallium nitride single crystal thick film wafer 4 larger than the standard size; S6: Grind and polish the gallium nitride single crystal thick film wafer 4 larger than the standard size to obtain a gallium nitride single crystal wafer material of standard size; S7: Perform high-temperature and high-vacuum baking and cleaning on the silicon carbide substrate sheet 3 larger than the standard size and the cylindrical silicon nitride ceramic protective cover 2 in a chlorine atmosphere; S8: Repeat steps S1 to S7.

[0021] This application uses a silicon carbide substrate wafer 3 larger than the standard size to grow a gallium nitride single crystal thick film 4 larger than the standard size on a substrate tray with a cylindrical silicon nitride ceramic protective cover 2. After grinding and polishing, a gallium nitride single crystal wafer material of the standard size is obtained. A gallium nitride device can be homoepitaxially prepared on the gallium nitride single crystal wafer material, reducing production costs and improving the yield.

[0022] Preferably, in step S1, a deposition window 21 is opened on the cylindrical silicon nitride ceramic protective cover 2, and the outer side wall of the cylindrical silicon nitride ceramic protective cover 2 is flexibly connected to the graphite tray 1. Exemplarily, the silicon carbide substrate wafer 3 is placed in the receiving groove 11 of the graphite tray 1. The outer diameter of the silicon carbide substrate wafer 3 is 3-6 mm larger than the outer diameter of the standard-size silicon carbide substrate wafer 3. The inner diameter of the receiving groove 11 is 1-2 mm larger than the diameter of the non-standard-size silicon carbide substrate wafer 3. The inner diameter of the deposition window 21 is 2-3 mm smaller than the outer diameter of the non-standard-size silicon carbide substrate wafer 3. The cylindrical silicon nitride ceramic protective cover 2 is installed on the graphite tray 1 on which the non-standard-size silicon carbide substrate wafer 3 is placed, and a flexible connector 5 is used to connect the graphite tray 1 and the cylindrical silicon nitride ceramic protective cover 2 to achieve non-rigid connection.

[0023] Preferably, in step S2, the substrate tray is inverted and installed on the substrate rotating base 8 in the growth chamber of the magnetron sputtering equipment. The rotating base 8 and the graphite tray 1 can be connected and fixed through a screw 9, specifically by connecting the rotating base 8 and the graphite base 13. Exemplarily, first, the sputtering gas argon and the reaction gas oxygen are introduced into the growth chamber of the magnetron sputtering equipment, and the ultra-thin zinc-aluminum-oxide polycrystalline film is prepared by the reactive co-sputtering process using a metal zinc target and a metal aluminum target. The thickness of the zinc-aluminum-oxide polycrystalline film is 10-50 nm, and the aluminum component content is 20-80%. After the zinc-aluminum-oxide polycrystalline film is prepared, the magnetron sputtering is stopped, and the sputtering gas argon and the reaction gas oxygen are stopped from being introduced; then, the sputtering gas argon and the reaction gas nitrogen are introduced into the growth chamber of the magnetron sputtering equipment, and the aluminum nitride polycrystalline film is prepared by the reactive sputtering process using a metal aluminum target. The thickness of the aluminum nitride polycrystalline film is 100-1000 nm. After the aluminum nitride polycrystalline film is prepared, the magnetron sputtering is stopped, and the sputtering gas argon and the reaction gas nitrogen are stopped from being introduced.

[0024] Preferably, in step S3, the cooled substrate tray is taken out from the growth chamber of the magnetron sputtering equipment and then placed in the high-temperature and high-vacuum annealing furnace chamber. Hydrogen is introduced and slowly heated to 1400-1600 °C, and heat preservation is carried out for 5-10 hours for high-temperature and high-vacuum annealing treatment. The zinc component in the ultra-thin zinc-aluminum-oxide polycrystalline film is decomposed and precipitated to form an ultra-thin porous aluminum oxide weakly bonded decoupling layer 6, and the thin aluminum nitride polycrystalline film is recrystallized to form a dislocation density not higher than 5×10 7 cm -2Thin aluminum nitride single crystal film template layer 7.

[0025] Preferably, in step S4, the substrate tray cooled down is taken out from the high-temperature and high-vacuum annealing furnace chamber. First, the cylindrical silicon nitride ceramic protective cover 2 is removed, and then a new cylindrical silicon nitride ceramic protective cover 2 is reinstalled. The substrate tray is inversely installed on the substrate rotating base 8 in the reaction chamber of the hydride vapor phase epitaxy equipment, and a gallium nitride single crystal thick film 4 with a thickness of 300 - 2000 µm is prepared by the hydride vapor phase epitaxy process.

[0026] Preferably, in step S5, the substrate tray cooled down in the hydride vapor phase epitaxy reaction chamber is taken out. First, the cylindrical silicon nitride ceramic protective cover 2 is removed, and then the non-standard size silicon carbide substrate wafer 3 with the gallium nitride single crystal thick film 4 prepared thereon is taken out from the receiving groove 11 of the graphite tray 1, and the gallium nitride single crystal thick film 4 is peeled off from the ultra-thin porous alumina weak bonding decoupling layer 6 to obtain a complete self-supporting non-standard size gallium nitride single crystal thick film 4.

[0027] Preferably, in step S6, the self-supporting non-standard size gallium nitride single crystal thick film 4 is subjected to cutting, grinding, and polishing processes to remove the redundant edges and the part of the gallium nitride single crystal thick film 4 layer with a relatively high dislocation density including the remaining alumina weak bonding decoupling layer 6 and the aluminum nitride single crystal film template layer 7, so as to obtain a standard size gallium nitride single crystal wafer material without warping, low stress, and low dislocation density. The dislocation density of the standard size gallium nitride single crystal wafer material is less than or equal to 1×10 6 cm -2 。

[0028] Preferably, in step S7, the non-standard size silicon carbide substrate wafer 3 peeled off is baked and cleaned under high temperature and high vacuum in a chlorine gas atmosphere to completely remove the remaining alumina weak bonding decoupling layer 6 on the surface, and the cylindrical silicon nitride ceramic protective cover 2 is baked under high temperature and high vacuum in a chlorine gas atmosphere to completely remove the gallium nitride material deposited on a partial area of the surface.

[0029] Preferably, in step S8, steps S1 to S7 are repeated to realize the reuse of the non-standard size silicon carbide substrate wafer.

[0030] Preferably, in step S1, the sizes of the standard size silicon carbide substrate wafers 3 include but are not limited to 2, 4, 6, 8, and 12 inches, and the sizes of the standard size gallium nitride single crystal wafers include but are not limited to 2, 4, 6, 8, and 12 inches.

[0031] It should be noted that for the specific solution to block the gap between the shielding substrate wafer 3 and the groove 11 of the graphite tray, a cylindrical silicon nitride ceramic protective cover 2 can be sleeved on the graphite tray 1, such as Figure 2 and Figure 3As shown in the figure, a receiving groove 11 for placing the substrate wafer 3 is formed at the top of the graphite tray 1, and the size of the receiving groove 11 is larger than that of the substrate wafer 3. The cylindrical silicon nitride ceramic protective cover 2 is sleeved on the graphite tray 1. A deposition window 21 is formed at the top of the cylindrical silicon nitride ceramic protective cover 2. The deposition window 21 is coaxially arranged with the receiving groove 11, that is, the centers of the deposition window 21 and the receiving groove 11 are at the same position in the vertical direction, and the inner diameter of the deposition window 21 is less than or equal to the outer diameter of the substrate wafer 3. The height of the substrate wafer 3 is less than or equal to the depth of the receiving groove 11. The depth of the deposition window 21 is greater than or equal to the thickness of the gallium nitride single crystal thick film 4. A flexible connecting member 5 is used to connect the graphite tray 1 and the cylindrical silicon nitride ceramic protective cover 2, thereby realizing a non-rigid connection. The flexible connecting member 5 includes: a positioning bolt 51, a fastening bolt 52, and a ceramic spring 53. One end of the ceramic spring 53 is connected to the positioning bolt 51, and the other end is connected to the fastening bolt 52. The positioning bolt 51 and the fastening bolt 52 are made of silicon nitride ceramic material, and the ceramic spring 53 is made of high-temperature and corrosion-resistant ceramic material. A positioning hole 12 is formed on the outer periphery of the graphite tray 1, and the positioning hole 12 is detachably connected to the positioning bolt 51. An installation hole 22 is formed in the circumferential direction of the silicon nitride ceramic protective cover 2, and the installation hole 22 is detachably connected to the fastening bolt 52. The substrate tray can be inverted and installed on the substrate rotating base of the hydride vapor phase epitaxy equipment. Compared with the prior art, the present invention has the following beneficial effects: 1. Compared with the gallium nitride single crystal thick film prepared by using a silicon carbide substrate wafer of standard size and also using a cylindrical silicon nitride ceramic protective cover, in order to avoid the deposition of gallium nitride material in the gap between the substrate wafer and the groove of the graphite tray and improve the wafer taking yield, the inner diameter of the deposition window at the top of the cylindrical silicon nitride ceramic protective cover can only be designed to be smaller than the outer diameter of the standard size substrate wafer. The outer diameter size of the prepared gallium nitride single crystal thick film wafer will be smaller than the standard size. After cutting, grinding, and polishing processes, only gallium nitride single crystal wafer materials with an outer diameter smaller than the standard size can be obtained, which affects the gallium nitride device process and reduces the number of gallium nitride devices prepared. In this application, a silicon carbide substrate wafer larger than the standard size is used to grow a gallium nitride single crystal thick film larger than the standard size on the substrate tray with a cylindrical silicon nitride ceramic protective cover. After cutting, grinding, and polishing, standard size gallium nitride single crystal wafer materials can be obtained, and gallium nitride devices can be homogeneously epitaxially prepared on the standard size gallium nitride single crystal wafer materials, reducing production costs and improving the yield; 2. In this application, by adopting a combined process of magnetron sputtering and high-temperature and high-vacuum annealing, an ultra-thin porous alumina weak bonding decoupling layer with a suitable thickness and an aluminum nitride single crystal thin film template layer with a suitable crystallization quality are prepared on the non-standard size silicon carbide substrate wafer, which can not only realize the reuse of the non-standard size silicon carbide substrate wafer, reduce the production cost of gallium nitride single crystal materials, but also be beneficial to improving the preparation and growth quality and the yield of gallium nitride single crystal thick film materials; 3. Compared with the graphite substrate tray without a cylindrical silicon nitride ceramic protective cover in the prior art, which can only be installed upright and not inverted. When installed upright, the deposition surface of the silicon carbide substrate wafer faces upward. In the magnetron sputtering or hydride vapor phase epitaxy process, particulate deposition is extremely likely to occur, affecting the growth quality of the prepared material and reducing the yield of the prepared material. In this application, the inner diameter of the deposition window of the silicon nitride ceramic protective cover is smaller than the outer diameter of the non-standard size silicon carbide substrate wafer and larger than the outer diameter of the standard silicon carbide substrate wafer. When the substrate tray is installed inverted on the substrate rotating base, the silicon carbide substrate wafer will not fall off. When the substrate tray is installed inverted, the deposition surface of the silicon carbide substrate wafer faces downward, which can avoid the particulate deposition phenomenon in the magnetron sputtering or hydride vapor phase epitaxy process. This is not only beneficial to improving the growth uniformity and surface flatness of the prepared material, but also beneficial to improving the crystallization quality of the material and the yield of the material.

[0032] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0033] In the present invention, unless otherwise clearly specified and defined, the terms "install", "connect", "connect", "fix", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or communication with each other; it can be directly connected, or indirectly connected through an intermediate medium. It can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the present invention, terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0035] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a gallium nitride single crystal wafer, characterized in that, It includes the following steps: S1: Place a silicon carbide substrate wafer larger than the standard size in the accommodation groove of the graphite tray, install a cylindrical silicon nitride ceramic protective cover on the graphite tray, and assemble to obtain a substrate tray; S2: Invert and install the substrate tray in S1 on the rotating base of the growth chamber of the magnetron sputtering equipment, and sequentially prepare a zinc aluminum oxide polycrystalline thin film and an aluminum nitride polycrystalline thin film on the silicon carbide substrate wafer larger than the standard size; S3: After cooling and taking out the substrate tray in S2, put it into the high-temperature and high-vacuum annealing furnace chamber, and perform high-temperature and high-vacuum annealing treatment. The zinc aluminum oxide polycrystalline thin film is converted into a porous aluminum oxide weakly bonded decoupling layer, and the aluminum nitride polycrystalline thin film is transformed into an aluminum nitride single crystal template layer; S4: After cooling and taking out the substrate tray in S3, invert and install it on the substrate rotating base in the reaction chamber of the hydride vapor phase epitaxy equipment, and deposit a gallium nitride single crystal thick film on the aluminum nitride single crystal template layer by using the hydride vapor phase epitaxy process; S5: Cool and take out the substrate tray in S4, remove the cylindrical silicon nitride ceramic protective cover, and peel off from the silicon carbide substrate wafer larger than the standard size to obtain a gallium nitride single crystal thick film wafer larger than the standard size; S6: Grind and polish the gallium nitride single crystal thick film wafer larger than the standard size to obtain a gallium nitride single crystal wafer of the standard size; S7: Bake and clean the silicon carbide substrate wafer larger than the standard size and the cylindrical silicon nitride ceramic protective cover under a chlorine atmosphere at high temperature and high vacuum; S8: Repeat steps S1 to S7.

2. The method for preparing a gallium nitride single crystal wafer according to claim 1, wherein In step S1, a deposition window is opened on the cylindrical silicon nitride ceramic protective cover, and the cylindrical silicon nitride ceramic protective cover is flexibly connected to the graphite tray.

3. The method for preparing a gallium nitride single crystal wafer according to claim 1, wherein In step S2, when preparing the zinc aluminum oxide polycrystalline thin film, argon is used as the sputtering gas and oxygen is used as the reaction gas, and a zinc aluminum oxide polycrystalline thin film with a thickness of 10 - 50 nm and an aluminum content of 20 - 80% is prepared by using the reactive co-sputtering process of a metal zinc target and a metal aluminum target.

4. The method for preparing a gallium nitride single crystal wafer according to claim 1, wherein In step S2, when preparing the aluminum nitride polycrystalline thin film, argon is used as the sputtering gas and nitrogen is used as the reaction gas, and an aluminum nitride polycrystalline thin film with a thickness of 100 - 1000 nm is prepared by using the reactive sputtering process of a metal aluminum target.

5. The method for preparing a gallium nitride single crystal wafer according to claim 1, wherein In step S3, the high-temperature and high-vacuum annealing treatment is: heating to 1400 - 1600 °C under a hydrogen atmosphere and holding for 5 - 10 hours in a vacuum state.

6. The method for preparing a gallium nitride single crystal wafer according to claim 1, wherein In step S3, the dislocation density of the aluminum nitride single crystal template layer is lower than 5×10 7 cm -2 .

7. The method for preparing a gallium nitride single crystal wafer according to claim 1, characterized in that, In step S4, the thickness of the gallium nitride single crystal thick film is 300 - 2000 µm.

8. The method for preparing a gallium nitride single crystal wafer according to claim 1, wherein, In the step S6, the dislocation density of the gallium nitride single crystal wafer with a standard size is lower than or equal to 1×10 6 cm -2 .

9. The method for preparing a gallium nitride single crystal wafer according to any one of claims 1-8, characterized in that, In step S1, the sizes of the standard-size silicon carbide substrate wafers include but are not limited to 2, 4, 6, 8, and 12 inches.

10. The method for preparing a gallium nitride single crystal wafer according to any one of claims 1-8, characterized in that, The sizes of the standard-size gallium nitride single crystal wafers include but are not limited to 2, 4, 6, 8, and 12 inches.

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