Method for epitaxial growth of gallium nitride epitaxial wafer based on selective area of amorphous substrate and gallium nitride epitaxial wafer

Abstract

The invention provides a method for epitaxial growth of a gallium nitride epitaxial wafer based on a selective area of an amorphous substrate and the gallium nitride epitaxial wafer. The gallium nitride epitaxial wafer comprises an amorphous substrate, a polycrystalline copper film, a silicon oxide layer and a gallium nitride layer which are arranged in a stacked mode. The polycrystalline copper film has an orientation [111]; the gallium nitride layer has [002] orientation. According to the gallium nitride epitaxial wafer provided by the invention, the combination of the amorphous substrate and the polycrystalline copper film is used as the substrate, a traditional single-crystal substrate and an over-thick copper substrate are replaced, the annealing time is shortened, meanwhile, the flatness and mechanical properties of the substrate are ensured by the amorphous substrate, the growth quality of the gallium nitride layer is improved, and large-scale popularization and application are facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor manufacturing, and relates to a gallium nitride epitaxial wafer, and particularly to a method for growing a gallium nitride epitaxial wafer by selective area epitaxy on an amorphous substrate and the gallium nitride epitaxial wafer. Background Art

[0002] Gallium nitride (GaN), as a typical representative of the third-generation semiconductor materials, has characteristics such as a high bandgap width, high conversion efficiency, high thermal conductivity, and high breakdown electric field strength, and has good application prospects in the fields of optoelectronics and microelectronics.

[0003] Gallium nitride-based micro light-emitting diodes (microLEDs) have high brightness, small size, low power consumption, and excellent color saturation, and are widely used in the preparation of pixel points of high-resolution display devices. The size of microLED pixel points is usually less than 100 μm, and some are only a few microns. At present, commercialization has been gradually realized.

[0004] Gallium nitride is mainly grown on single-crystal substrates such as sapphire (0001), silicon carbide (0001), and single-crystal silicon (111). Gallium nitride has a good lattice match with silicon carbide and a small mismatch, but the substrate price is relatively high; although the prices of gallium nitride and sapphire and single-crystal silicon substrates are relatively low, the mismatch is large, and it is easy to generate large stress, resulting in a high defect density in the epitaxial GaN layer, which severely restricts the application of GaN materials.

[0005] In addition, technicians also grow gallium nitride on a copper substrate with a certain thickness. However, the copper used as the substrate needs to have certain characteristics and mechanical properties, such as a high surface flatness and a small roughness, and is not easily deformed at high temperatures. Due to these limitations, the copper that needs to be annealed subsequently needs to have a relatively large thickness, generally not less than 30 μm, and when used as a substrate, it should have a greater thickness. A thicker copper substrate requires a longer annealing time, thereby reducing the production efficiency. At the same time, a thicker copper substrate has a larger deformation amount after annealing, and the flatness and mechanical properties are reduced accordingly, ultimately having an adverse impact on the quality of the gallium nitride epitaxial layer.

[0006] At present, the selective area epitaxy growth technology is widely used in the fields of semiconductor epitaxy growth and device manufacturing. By using selective area epitaxy growth, lateral epitaxy and the preparation of special structures such as quantum dots and quantum wells can be realized. However, how to organically combine the advantages of selective area epitaxy growth with the size specifications of microLEDs to find a method that can match the two has not been reported yet.

[0007] It can be seen from this that how to provide a gallium nitride epitaxial wafer and a preparation method thereof, avoid the use of traditional single crystal substrates and overly thick copper substrates, improve the growth quality of the gallium nitride epitaxial layer, and at the same time organically combine the advantages of selective area epitaxy growth with the size specifications of microLEDs, reduce production costs while improving device reliability, and simplify the preparation method has become an urgent problem to be solved by those skilled in the art at present. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for growing a gallium nitride epitaxial wafer by selective area epitaxy on an amorphous substrate and a gallium nitride epitaxial wafer. The present invention avoids the use of traditional single crystal substrates and overly thick copper substrates, improves the growth quality of the gallium nitride epitaxial layer, and at the same time organically combines the advantages of selective area epitaxy growth with the size specifications of microLEDs, reduces production costs while improving device reliability, simplifies the preparation method, and is conducive to large-scale popularization and application.

[0009] To achieve the purpose of this invention, the following technical solutions are adopted in the present invention:

[0010] In the first aspect, the present invention provides a gallium nitride epitaxial wafer, which includes an amorphous substrate, a polycrystalline copper film, a silicon oxide layer, and a gallium nitride layer stacked; the polycrystalline copper film has a

[111] orientation; the gallium nitride layer has a

[002] orientation.

[0011] The gallium nitride epitaxial wafer provided by the present invention uses a combination of an amorphous substrate and a polycrystalline copper film as the substrate, replacing the traditional single crystal substrate and overly thick copper substrate, shortening the annealing time. At the same time, the amorphous substrate ensures the flatness and mechanical properties of the substrate, improves the growth quality of the gallium nitride layer, and is conducive to large-scale popularization and application.

[0012] Preferably, a passivation layer is further provided between the polycrystalline copper film and the silicon oxide layer to improve the high-temperature resistance, ammonia resistance, and chlorine corrosion resistance of the substrate.

[0013] Preferably, the material of the passivation layer includes aluminum nitride, and the aluminum nitride has a

[002] orientation.

[0014] Preferably, the thickness of the passivation layer is 30 - 500 nm, for example, it can be 30 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, or 500 nm, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0015] In the present invention, the specific thickness of the passivation layer is determined by subsequent patterning processes and the growth process of the gallium nitride layer.

[0016] Preferably, the material of the amorphous substrate includes mica, quartz or glass.

[0017] Preferably, the grain size of the polycrystalline copper film is ≥5 μm, for example, it can be 5 μm, 5.2 μm, 5.4 μm, 5.6 μm, 5.8 μm, 6 μm, 6.2 μm, 6.4 μm, 6.6 μm, 6.8 μm or 7 μm, but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0018] Preferably, the thickness of the polycrystalline copper film is 0.5 - 10 μm, for example, it can be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm or 10 μm, but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0019] In the present invention, the specific thickness of the copper film is determined by subsequent annealing treatment, the thickness of the epitaxial layer and the magnitude of the stress in the epitaxial layer.

[0020] Preferably, the thickness of the silicon oxide layer is 100 - 4000 nm, for example, it can be 100 nm, 500 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm or 4000 nm, but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0021] In the present invention, the specific thickness of the silicon oxide is determined by the growth process of the subsequent gallium nitride layer.

[0022] In a second aspect, the present invention provides a method for preparing a gallium nitride epitaxial wafer as described in the first aspect. The preparation method is based on selective area epitaxial growth of a gallium nitride epitaxial wafer on an amorphous substrate, and includes the following steps:

[0023] (1) Select an amorphous substrate, and deposit a copper film on one side surface of the amorphous substrate to obtain a first substrate;

[0024] (2) Anneal the first substrate obtained in step (1) to transform the copper film into a polycrystalline copper film with a

[111] orientation to obtain a second substrate;

[0025] (3) Grow a silicon oxide layer on the polycrystalline copper film of the second substrate obtained in step (2) to obtain a third substrate;

[0026] (4) Pattern the silicon oxide layer of the third substrate obtained in step (3) to obtain a fourth substrate;

[0027] (5) growing a

[002] -oriented gallium nitride layer on the surface of the patterned side of the fourth substrate obtained in step (4) to obtain a single-crystalline gallium nitride epitaxial wafer in a selected area.

[0028] The method provided by the present invention organically combines the advantages of selective epitaxial growth with the size specifications of microLEDs to produce a gallium nitride epitaxial wafer with a single crystal in the selected area, thereby reducing production costs while improving device reliability, simplifying the preparation method, and facilitating large-scale promotion and application.

[0029] Preferably, between step (2) and step (3), the method further includes: epitaxially growing a passivation layer on the polycrystalline copper film of the second substrate.

[0030] Preferably, the amorphous substrate in step (1) is subjected to a cleaning step before depositing the copper film.

[0031] Preferably, the copper film deposition method in step (1) includes vacuum evaporation or physical sputtering.

[0032] Preferably, the annealing time in step (2) is 0.5-10 h, for example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h or 10 h, but is not limited to the listed values, and other values not listed within the numerical range are also applicable.

[0033] Preferably, the method for growing the silicon oxide layer in step (3) includes plasma enhanced chemical vapor deposition.

[0034] Preferably, the patterning process in step (4) includes laser etching or plasma etching, so as to minimize the adverse effects of surface grain boundaries on the gallium nitride epitaxial layer grown thereon.

[0035] Preferably, the depth of the patterning process in step (4) is greater than or equal to the thickness of the silicon oxide layer, so as to expose the surface of the passivation layer or the polycrystalline copper film, and the specific depth, shape, size and duty cycle are determined by the quality of the epitaxial passivation layer and the thickness of the gallium nitride layer, so as to minimize the influence of the grain boundary on the epitaxial layer and maximize the lateral growth of the gallium nitride layer.

[0036] Preferably, the method for growing the gallium nitride layer in step (5) includes hydride vapor phase epitaxy, i.e. HVPE.

[0037] As a preferred technical solution of the first aspect of the present invention, the method comprises the following steps:

[0038] (1) selecting an amorphous substrate, and depositing a copper film on one surface of the amorphous substrate by vacuum evaporation or physical sputtering after cleaning to obtain a first substrate;

[0039] (2) Anneal the first substrate obtained in step (1) for 0.5 - 10 h to transform the copper film into a polycrystalline copper film with a

[111] orientation, obtaining a second substrate;

[0040] (3) Grow a silicon oxide layer on the polycrystalline copper film of the second substrate obtained in step (2) by plasma-enhanced chemical vapor deposition, obtaining a third substrate;

[0041] (4) Pattern the silicon oxide layer of the third substrate obtained in step (3) by laser etching or plasma etching, and control the depth of the patterning process ≥ the thickness of the silicon oxide layer, obtaining a fourth substrate;

[0042] (5) Grow a gallium nitride layer with a

[002] orientation on the surface of the patterned side of the fourth substrate obtained in step (4) by hydride vapor epitaxy, obtaining a gallium nitride epitaxial wafer with a single-crystal selected area range.

[0043] Among them, between step (2) and step (3), it also includes: epitaxially growing a gallium nitride layer with a

[002] orientation on the polycrystalline copper film of the second substrate.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The gallium nitride epitaxial wafer provided by the present invention uses a combination of an amorphous substrate and a polycrystalline copper film as a substrate, replacing the traditional single-crystal substrate and overly thick copper substrate, shortening the annealing time. At the same time, the amorphous substrate ensures the flatness and mechanical properties of the substrate, improves the growth quality of the gallium nitride layer, and is conducive to large-scale popularization and application;

[0046] (2) The method provided by the present invention organically combines the advantages of selective area epitaxial growth with the size specifications of microLEDs, prepares a gallium nitride epitaxial wafer with a single-crystal selected area range, reduces the production cost while improving the device reliability, simplifies the preparation method, and is conducive to large-scale popularization and application. Description of the Drawings

[0047] Figure 1 is a flowchart of the method for selective area epitaxial growth of gallium nitride epitaxial wafers based on an amorphous substrate provided in Example 1;

[0048] Figure 2 is an electron backscatter diffraction pattern of the polycrystalline copper film in the gallium nitride epitaxial wafer provided in Example 1;

[0049] Figure 3 is the test rocking curve of the gallium nitride epitaxial wafer provided in Example 1;

[0050] Figure 4It is the electron backscatter diffraction pattern of the aluminum nitride layer in the gallium nitride epitaxial wafer provided by Example 2. Detailed implementation manners

[0051] The technical solution of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the described embodiments are only helpful for understanding the present invention and should not be regarded as specific limitations to the present invention.

[0052] Example 1

[0053] This example provides a method for growing a gallium nitride epitaxial wafer by selective area epitaxy on an amorphous substrate. As Figure 1 shown, the method includes the following steps:

[0054] (1) Select glass as the amorphous substrate. After cleaning, deposit a 1-μm copper film on one surface of the amorphous substrate by vacuum evaporation to obtain a first substrate;

[0055] (2) Anneal the first substrate obtained in step (1) at 1085 °C for 1 h to transform the copper film into a polycrystalline copper film with a

[111] orientation and a grain size of 10 μm (see Figure 2 ), to obtain a second substrate;

[0056] (3) Grow a 200-nm silicon oxide layer on the polycrystalline copper film of the second substrate obtained in step (2) by plasma-enhanced chemical vapor deposition to obtain a third substrate;

[0057] (4) Pattern the silicon oxide layer of the third substrate obtained in step (3) by plasma etching, and control the depth of the patterning process to be 200 nm to expose the surface of the polycrystalline copper film, to obtain a fourth substrate;

[0058] (5) Grow a gallium nitride layer with a

[002] orientation on the patterned side surface of the fourth substrate obtained in step (4) by low-pressure (0.03 MPa) hydride vapor epitaxy to obtain a gallium nitride epitaxial wafer with a single-crystal selected area range.

[0059] The measured rocking curve of the (002) diffraction peak of the gallium nitride epitaxial wafer obtained in this example is shown in Figure 3 , the measurement step size is 0.02°, and the scanning time for each step is 0.01 s.

[0060] It can be seen from Figure 3 that: the out-of-plane of gallium nitride of the gallium nitride epitaxial wafer obtained in this example is a single (002) orientation, and the crystal quality is good, and it can be used as an epitaxial template for other materials.

[0061] Example 2

[0062] This embodiment provides a method for growing gallium nitride epitaxial wafers by selective area epitaxy on an amorphous substrate. The method includes the following steps:

[0063] (1) Select quartz as the amorphous substrate. After cleaning, deposit a 10-μm copper film on one side surface of the amorphous substrate by physical sputtering to obtain a first substrate;

[0064] (2) Anneal the first substrate obtained in step (1) at 1085 °C for 9 h to transform the copper film into a polycrystalline copper film with a

[111] orientation and a grain size of 30 μm, obtaining a second substrate;

[0065] (3) Epitaxially grow a 200-nm aluminum nitride layer with a

[002] orientation on the polycrystalline copper film of the second substrate (see Figure 4 );

[0066] (4) Grow a 1000-nm silicon oxide layer on the aluminum nitride layer of the second substrate obtained in step (3) by plasma-enhanced chemical vapor deposition to obtain a third substrate;

[0067] (5) Pattern the silicon oxide layer of the third substrate obtained in step (4) by plasma etching and control the depth of the patterning process to be 1000 nm to expose the surface of the aluminum nitride layer, obtaining a fourth substrate;

[0068] (6) Grow a gallium nitride layer with a

[002] orientation on the patterned side surface of the fourth substrate obtained in step (5) by atmospheric pressure (0.1 MPa) hydride vapor epitaxy to obtain a gallium nitride epitaxial wafer with a single-crystal selective area range.

[0069] The measured rocking curve of the gallium nitride epitaxial wafer obtained in this embodiment is similar to that in Example 1, so it will not be elaborated here.

[0070] Example 3

[0071] This embodiment provides a method for growing gallium nitride epitaxial wafers by selective area epitaxy on an amorphous substrate. The method includes the following steps:

[0072] (1) Select mica as the amorphous substrate. After cleaning, deposit an 8-μm copper film on one side surface of the amorphous substrate by vacuum evaporation to obtain a first substrate;

[0073] (2) Anneal the first substrate obtained in step (1) at 1085 °C for 3 h to transform the copper film into a polycrystalline copper film with a

[111] orientation and a grain size of 6 μm, obtaining a second substrate;

[0074] (3) Epitaxially grow a 300-nm aluminum nitride layer with a

[002] orientation on the polycrystalline copper film of the second substrate;

[0075] (4) A 100 - nm thick silicon oxide layer is grown on the aluminum nitride layer of the second substrate obtained in step (3) by plasma - enhanced chemical vapor deposition to obtain a third substrate;

[0076] (5) The silicon oxide layer of the third substrate obtained in step (4) is patterned by plasma etching, and the depth of the patterning is controlled to be 100 nm to expose the surface of the aluminum nitride layer, obtaining a fourth substrate;

[0077] (6) A gallium nitride layer with a

[002] orientation is grown on the patterned surface of the fourth substrate obtained in step (5) by atmospheric - pressure (0.1 MPa) hydride vapor epitaxy to obtain a gallium nitride epitaxial wafer with a single - crystal selection range.

[0078] The measured rocking curve of the gallium nitride epitaxial wafer obtained in this example is similar to that of Example 1, so it will not be elaborated here.

[0079] Example 4

[0080] This example provides a method for growing a gallium nitride epitaxial wafer by selective area epitaxy on an amorphous substrate. Except that the depth of the patterning in step (5) is changed to 1200 nm to expose the surface of the polycrystalline copper film, the remaining steps and conditions are the same as those in Example 2, so it will not be elaborated here.

[0081] The measured rocking curve of the gallium nitride epitaxial wafer obtained in this example is similar to that of Example 1, so it will not be elaborated here.

[0082] Example 5

[0083] This example provides a method for growing a gallium nitride epitaxial wafer by selective area epitaxy on an amorphous substrate. Except that the depth of the patterning in step (5) is changed to 400 nm to expose the surface of the polycrystalline copper film, the remaining steps and conditions are the same as those in Example 3, so it will not be elaborated here.

[0084] The measured rocking curve of the gallium nitride epitaxial wafer obtained in this example is similar to that of Example 1, so it will not be elaborated here.

[0085] Comparative Example 1

[0086] This comparative example provides a method for growing a gallium nitride epitaxial wafer, and the method includes the following steps:

[0087] (1) A Cu substrate with a thickness of 1000 μm is selected as the first substrate;

[0088] (2) The first substrate in step (1) is annealed at 1085 °C for 24 h to obtain a second substrate;

[0089] (3) A 200-nm-thick silicon oxide layer is grown on the surface of the second substrate obtained in step (2) by plasma-enhanced chemical vapor deposition to obtain a third substrate;

[0090] (4) The silicon oxide layer of the third substrate obtained in step (3) is patterned by plasma etching, and the depth of the patterning is controlled to be 200 nm to expose the surface of the Cu substrate, obtaining a fourth substrate;

[0091] (5) A gallium nitride layer with a

[002] orientation is grown on the patterned side surface of the fourth substrate obtained in step (4) by low-pressure (0.03 MPa) hydride vapor epitaxy to obtain a gallium nitride epitaxial wafer with a single-crystalline selected area range.

[0092] Compared with depositing a copper film on the surface of an amorphous substrate in Example 1, in this comparative example, a Cu substrate is directly selected as the first substrate. To maintain the hardness and flatness of the substrate, the Cu substrate requires a relatively large thickness (1000 μm). Since the annealing time is proportional to the thickness of the Cu substrate, a longer annealing time (24 h) is required. In addition, during the deposition of gallium nitride, the temperature needs to be raised to 900 °C. Since Cu has a relatively large thermal expansion coefficient, the silicon oxide layer is extremely prone to cracking. The cooling process after the gallium nitride deposition process will also cause cracks in the gallium nitride, and the generation of cracks has an adverse effect on the quality of the gallium nitride epitaxial wafer.

[0093] It can be seen that the gallium nitride epitaxial wafer provided by the present invention uses a combination of an amorphous substrate and a polycrystalline copper film as the substrate, replacing the traditional single-crystalline substrate and overly thick copper substrate, shortening the annealing time. At the same time, the amorphous substrate ensures the flatness and mechanical properties of the substrate, improves the growth quality of the gallium nitride layer, and is conducive to large-scale popularization and application.

[0094] In addition, the method provided by the present invention organically combines the advantages of selective area epitaxial growth with the size specifications of microLEDs, prepares a gallium nitride epitaxial wafer with a single-crystalline selected area range, reduces the production cost while improving the device reliability, simplifies the preparation method, and is conducive to large-scale popularization and application.

[0095] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A gallium nitride epitaxial wafer, characterized in that, The gallium nitride epitaxial wafer includes an amorphous substrate, a polycrystalline copper film, a silicon oxide layer, and a gallium nitride layer that are stacked; The polycrystalline copper film has a [111] orientation; The gallium nitride layer has a [002] orientation.

2. The gallium nitride epitaxial wafer according to claim 1, characterized in that, A passivation layer is further provided between the polycrystalline copper film and the silicon oxide layer; Preferably, the material of the passivation layer includes aluminum nitride, and the aluminum nitride has a [002] orientation; Preferably, the thickness of the passivation layer is 30 - 500 nm.

3. The gallium nitride epitaxial wafer according to claim 1 or 2, characterized in that, The material of the amorphous substrate includes mica, quartz, or glass; Preferably, the grain size of the polycrystalline copper film is ≥5 μm; Preferably, the thickness of the polycrystalline copper film is 0.5 - 10 μm; Preferably, the thickness of the silicon oxide layer is 100 - 4000 nm.

4. A method for preparing a gallium nitride epitaxial wafer according to any one of claims 1-3, characterized in that, The preparation method is based on selective area epitaxial growth of a gallium nitride epitaxial wafer on an amorphous substrate, and includes the following steps: (1) Select an amorphous substrate, and deposit a copper film on one side surface of the amorphous substrate to obtain a first substrate; (2) Anneal the first substrate obtained in step (1) to transform the copper film into a polycrystalline copper film with a [111] orientation to obtain a second substrate; (3) Grow a silicon oxide layer on the polycrystalline copper film of the second substrate obtained in step (2) to obtain a third substrate; (4) Pattern the silicon oxide layer of the third substrate obtained in step (3) to obtain a fourth substrate; (5) Grow a gallium nitride layer with a [002] orientation on the patterned side surface of the fourth substrate obtained in step (4) to obtain a gallium nitride epitaxial wafer with a single crystal in the selected area range.

5. The method according to claim 4, wherein Between step (2) and step (3), it further includes: epitaxially growing a passivation layer on the polycrystalline copper film of the second substrate.

6. The method according to claim 4 or 5, characterized in that The amorphous substrate in step (1) undergoes a cleaning step before depositing the copper film; Preferably, the deposition method of the copper film in step (1) includes vacuum evaporation or physical sputtering.

7. The method according to any one of claims 4 to 6, characterized in that, The annealing time in step (2) is 0.5 - 10 h.

8. The method according to any one of claims 4 to 7, characterized in that The growth method of the silicon oxide layer in step (3) includes plasma enhanced chemical vapor deposition.

9. The method according to any one of claims 4-8, characterized in that, The patterning method in step (4) includes laser etching or plasma etching; Preferably, the depth of the patterning in step (4) is ≥ the thickness of the silicon oxide layer; Preferably, the growth method of the gallium nitride layer in step (5) includes hydride vapor phase epitaxy.

10. The method according to any one of claims 4-9, characterized in that, The method includes the following steps: (1) Select an amorphous substrate, clean it, and deposit a copper film on one side surface of the amorphous substrate by vacuum evaporation or physical sputtering to obtain a first substrate; (2) Anneal the first substrate obtained in step (1) for 0.5 - 10 h to transform the copper film into a polycrystalline copper film with a [111] orientation to obtain a second substrate; (3) Grow a silicon oxide layer on the polycrystalline copper film of the second substrate obtained in step (2) by plasma enhanced chemical vapor deposition to obtain a third substrate; (4) Pattern the silicon oxide layer of the third substrate obtained in step (3) by laser etching or plasma etching, and control the depth of the patterning to be ≥ the thickness of the silicon oxide layer to obtain a fourth substrate; (5) A gallium nitride layer with a [002] orientation is grown on the patterned side surface of the fourth substrate obtained in step (4) by metalorganic chemical vapor deposition to obtain a gallium nitride epitaxial wafer with a single crystal in the selected area range; Wherein, between step (2) and step (3), it further includes: epitaxially growing an aluminum nitride layer with a [002] orientation on the polycrystalline copper film of the second substrate.

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