A homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate and a preparation method thereof

Abstract

The present invention provides a homoepitaxial wafer of an n-type gallium oxide single crystal substrate and a preparation method thereof, belonging to the technical field of gallium oxide epitaxy. The method comprises growing a dielectric layer on the back of an n-type gallium oxide single crystal substrate to cover the entire back of the substrate, obtaining a substrate after the dielectric layer is grown; polishing the front of the substrate after the dielectric layer is grown under the protection of the dielectric layer to obtain a substrate after the front polishing; performing homoepitaxial gallium oxide on the front of the substrate after the front polishing under the protection of the dielectric layer to obtain a homoepitaxial substrate; removing the dielectric layer on the back of the homoepitaxial substrate to obtain a substrate without the back dielectric layer; polishing the front of the substrate without the back dielectric layer to obtain a homoepitaxial wafer of an n-type gallium oxide single crystal substrate. The present invention can solve the problem of increased resistivity of the substrate after homoepitaxial gallium oxide.

Description

Technical Field

[0001] The present invention relates to the technical field of gallium oxide epitaxy, and in particular to a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate and a preparation method thereof. Background Art

[0002] As the fourth-generation wide bandgap semiconductor material, gallium oxide has the advantages of wider bandgap, higher breakdown electric field, and larger baliga figure of merit compared to third-generation semiconductors such as silicon carbide and gallium nitride. It can be used to prepare high-voltage and high-power electronic devices, and has great application prospects in power conversion such as electric vehicles, wind power generation, electric ships and high-speed railways.

[0003] A high-voltage vertical structure gallium oxide power device requires a gallium oxide epitaxial layer of a certain thickness. The structure of a gallium oxide homoepitaxial wafer is as follows: a lightly doped n-type gallium oxide epitaxial layer is homoepitaxially grown on a heavily doped n-type gallium oxide single crystal substrate. For n-type gallium oxide single crystals, the higher the doping concentration, the lower the resistivity, and the darker the blue color of the substrate. During the gallium oxide homoepitaxial growth process, the n-type gallium oxide single crystal substrate is placed in a high-temperature environment. After the epitaxial growth is completed, the electrical properties of the n-type gallium oxide single crystal substrate will change, and the resistivity will increase significantly. From the appearance, it can be seen that the blue color of most of the middle area of ​​the gallium oxide epitaxial wafer will become lighter, or even colorless. When using this color-changing gallium oxide epitaxial wafer to prepare gallium oxide power devices, the device on-resistance will increase significantly, resulting in a decrease in device performance.

[0004] The existing method is to perform high-temperature annealing on the gallium oxide homoepitaxial wafer after epitaxy. Although the resistivity of the gallium oxide homoepitaxial wafer substrate can be partially restored, the resistivity of the substrate after annealing is still higher than that before epitaxy. This will still cause the on-resistance of the prepared gallium oxide power device to be relatively large, which is not conducive to improving the performance of the device and reducing reliability. Summary of the invention

[0005] The invention provides a homoepitaxial wafer of an n-type gallium oxide single crystal substrate and a preparation method thereof, so as to solve the problem of increased substrate resistivity after homoepitaxial growth of gallium oxide.

[0006] In a first aspect, the present invention provides a method for preparing a homoepitaxial wafer of an n-type gallium oxide single crystal substrate, comprising: growing a dielectric layer on the back side of the n-type gallium oxide single crystal substrate to cover the entire back side of the substrate to obtain a substrate after the dielectric layer is grown; polishing the front side of the substrate after the dielectric layer is grown under the protection of the dielectric layer to obtain a substrate after the front side is polished; performing gallium oxide homoepitaxial growth on the front side of the substrate after the front side is polished under the protection of the dielectric layer to obtain a homoepitaxial substrate; removing the dielectric layer on the back side of the homoepitaxial substrate to obtain a substrate without the back side dielectric layer; polishing the front side of the substrate without the back side dielectric layer to obtain a homoepitaxial wafer of the n-type gallium oxide single crystal substrate.

[0007] In a possible implementation, removing the dielectric layer on the back side of the homoepitaxial substrate to obtain the substrate without the back dielectric layer includes: removing the dielectric layer on the back side of the homoepitaxial substrate by a grinding process to obtain the substrate without the back dielectric layer.

[0008] In a possible implementation manner, the material of the dielectric layer includes silicon oxide, silicon nitride or aluminum oxide.

[0009] In a possible implementation, the thickness of the dielectric layer ranges from 50 to 1000 nanometers.

[0010] In a possible implementation manner, a method for growing a dielectric layer on the back side of the n-type gallium oxide single crystal substrate includes magnetron sputtering, thermal evaporation or plasma enhanced chemical vapor deposition.

[0011] In a possible implementation, the gallium oxide homoepitaxial growth method includes halide vapor phase epitaxy, metal organic chemical vapor deposition or low pressure chemical vapor deposition.

[0012] In a possible implementation, the gallium oxide homoepitaxial growth temperature ranges from 950 to 1100° C., and the oxygen flow rate ranges from 30 to 500 mL / min.

[0013] In a possible implementation manner, the n-type gallium oxide single crystal substrate is a heavily doped substrate.

[0014] In a possible implementation, the doping concentration of the n-type gallium oxide single crystal substrate is greater than 1E18 cm -3 , resistivity is less than 0.04Ω·cm.

[0015] In a second aspect, the present invention provides a homoepitaxial wafer of an n-type gallium oxide single crystal substrate, which is prepared based on the method for preparing a homoepitaxial wafer of an n-type gallium oxide single crystal substrate as described in any one of the above items.

[0016] The present invention provides a homoepitaxial wafer of an n-type gallium oxide single crystal substrate and a preparation method thereof. The present invention grows a dielectric layer on the back of the substrate before gallium oxide homoepitaxial growth, and performs gallium oxide homoepitaxial growth under the protection of the dielectric layer, which can isolate high-temperature oxygen from the back of the substrate during epitaxy, reduce the contact between the back of the gallium oxide single crystal substrate and the high-temperature oxygen, and can effectively ensure that the resistivity of the gallium oxide single crystal substrate is not affected by oxygen during the epitaxy process, thereby solving the problem of increased substrate resistivity after gallium oxide homoepitaxial growth.

[0017] In addition, under the protection of the dielectric layer, the generation of polycrystalline gallium oxide on the back side of the gallium oxide single crystal substrate can be avoided, reducing the damage to the back side caused by homoepitaxial growth. At the same time, the back dielectric layer can be removed by back polishing after epitaxy in the normal process, which has little impact on the original process efficiency.

[0018] Third, growing the back dielectric layer before homoepitaxial growth and before polishing the front surface can also avoid contamination or scratching of the polishing surface during the growth of the dielectric layer. At the same time, the back dielectric layer can also protect the back surface during polishing the front surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 is a schematic structural diagram of a gallium oxide homoepitaxial wafer provided in an embodiment of the present invention;

[0021] Figure 2 It is a flow chart of the implementation of the method for preparing a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate provided by an embodiment of the present invention;

[0022] Figure 3 They are the resistivity test results of the gallium oxide homoepitaxial wafer prepared without adding a dielectric layer;

[0023] Figure 4 These are the resistivity test results of gallium oxide homoepitaxial wafers prepared with an additional dielectric layer. DETAILED DESCRIPTION

[0024] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0025] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0026] The following is a detailed description of the implementation of the present invention in conjunction with the specific drawings:

[0027] Figure 1 is a schematic diagram of the structure of a gallium oxide homoepitaxial wafer provided in an embodiment of the present invention; Figure 1 , a gallium oxide homoepitaxial layer is grown on the front side of the n-type gallium oxide single crystal substrate. Exemplarily, the n-type gallium oxide single crystal substrate is heavily doped, and the gallium oxide homoepitaxial layer is lightly doped. The higher the doping concentration of the n-type gallium oxide single crystal substrate, the lower the resistivity. Gallium oxide homoepitaxial wafers require the substrate resistivity to be as low as possible.

[0028] During the process of gallium oxide epitaxy, the resistivity of the n-type gallium oxide single crystal substrate will increase significantly. The commonly used technical solution is to restore the resistivity of the substrate part of the gallium oxide homoepitaxial wafer by high-temperature annealing after gallium oxide epitaxy. For example, the annealing temperature of the annealing process is between 1000-1150°C, the annealing time is 0.5-5h, and the annealing carrier gas is inert gas nitrogen.

[0029] Although the high-temperature annealing technology can partially restore the resistivity of the gallium oxide homoepitaxial wafer, the resistivity of the substrate after annealing is still higher than that before epitaxy. That is, annealing the gallium oxide homoepitaxial wafer in a high-temperature inert atmosphere can only partially improve the electrical properties, and there is a certain gap with the substrate resistivity before epitaxy, that is, the resistivity of the gallium oxide substrate is not completely restored. This will still cause the on-resistance of the prepared gallium oxide power device to be relatively large, which is not conducive to improving the performance of the device and reducing reliability.

[0030] In order to facilitate comparison with the present application, an example is given below to illustrate the process of preparing gallium oxide homoepitaxial wafers by the existing high temperature annealing method. The preparation process of a HVPE (halide vapor phase epitaxy) gallium oxide homoepitaxial wafer is as follows:

[0031] Step 1), placing the front-polished gallium oxide single crystal substrate into a HVPE chamber for epitaxial growth to obtain an HVPE gallium oxide homoepitaxial wafer.

[0032] Step 2), placing the HVPE gallium oxide homoepitaxial wafer into an annealing furnace, and performing high temperature annealing in an inert atmosphere to restore the resistivity of the substrate portion.

[0033] Step 3), finally, the HVPE gallium oxide homoepitaxial wafer is processed to remove the polycrystalline gallium oxide grown on the back and the rough morphology of the front epitaxial layer, so as to obtain a HVPE gallium oxide homoepitaxial wafer with high surface quality. It should be noted that the polycrystalline gallium oxide grown on the back here is an additional product that is not expected to grow in normal growth. If it is not removed, it will affect the flatness of the back and will be inconvenient for subsequent device preparation. For example, an uneven back will easily distort the photolithography pattern in device preparation.

[0034] The inventors of this application discovered during the research and development process that during homoepitaxial growth of gallium oxide, a large amount of oxygen needs to be introduced to provide oxygen elements for gallium oxide growth. During the process of homoepitaxial growth of gallium oxide, since the gallium oxide single crystal substrate is in a high temperature and oxygen atmosphere, oxygen will have a negative impact on the resistivity of the gallium oxide single crystal substrate. Specifically, under high temperature and oxygen conditions, oxygen will diffuse into the gallium oxide crystal and form bonds with intentionally doped donors (silicon or Sn), resulting in compensation of the free electrons provided by the donors, increasing the resistivity of gallium oxide, and further increasing the on-resistance of the developed gallium oxide power device, and reducing the performance of the device.

[0035] Therefore, the embodiment of the present invention solves the problem of increased substrate resistivity after homoepitaxial growth of gallium oxide by growing a dielectric layer on the back side of an n-type gallium oxide single crystal substrate.

[0036] Figure 2 1 is a flowchart of a method for preparing a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate provided by an embodiment of the present invention. Figure 2 , the method comprising:

[0037] Step 201 : growing a dielectric layer on the back side of an n-type gallium oxide single crystal substrate to cover the entire back side of the substrate, thereby obtaining a substrate after the dielectric layer is grown.

[0038] In some embodiments, the n-type gallium oxide single crystal substrate refers to a gallium oxide single crystal substrate whose conductivity type is electron.

[0039] In some embodiments, the n-type gallium oxide single crystal substrate is in a state where the upper and lower surfaces are ground but chemical mechanical polishing is not performed. It should be noted that because the front surface of the substrate will be polished in the subsequent steps, the substrate can be in an unpolished state here. In addition, because the substrate is easily contaminated and scratched after polishing, for example, when the dielectric layer is grown on the back, the front polished surface is easily contaminated, resulting in the need for secondary polishing, so the substrate can be in an unpolished state here.

[0040] In some embodiments, the method further includes cleaning the n-type gallium oxide single crystal substrate before step 201. For example, the cleaning method may be ultrasonic cleaning using a dewaxing solution, ethanol, and deionized water in sequence, with each cleaning time being 5-20 minutes. Accordingly, a dielectric layer is prepared on the back of the cleaned n-type gallium oxide single crystal substrate.

[0041] In some embodiments, a method of growing a dielectric layer on the back side of the n-type gallium oxide single crystal substrate includes magnetron sputtering, thermal evaporation, or plasma enhanced chemical vapor deposition.

[0042] In some embodiments, the material of the dielectric layer includes silicon oxide, silicon nitride, or aluminum oxide.

[0043] In some embodiments, the dielectric layer has a thickness in a range of 50 to 1000 nanometers.

[0044] In some embodiments, a dielectric layer is prepared on the back of an n-type gallium oxide single crystal substrate. The material of the dielectric layer is SiO2, and the thickness ranges from 50nm to 1000nm. The method for preparing the dielectric layer is magnetron sputtering. The RF power of magnetron sputtering ranges from 100 to 150W, the argon gas flow ranges from 20 to 30sccm, and the growth time ranges from 30 to 60min.

[0045] It should be noted here that the grown dielectric layer needs to cover the entire back side of the substrate.

[0046] In some embodiments, the n-type gallium oxide single crystal substrate is a heavily doped substrate. For example, the doping concentration of the n-type gallium oxide single crystal substrate is greater than 1E18 cm -3 , the resistivity is less than 0.04Ω·cm. It should be noted here that the purpose of heavily doped substrates is to have low resistivity, and heavily doped substrates are more easily affected by oxygen during homoepitaxial growth, thereby increasing resistivity.

[0047] Step 202 , under the protection of the dielectric layer, the substrate after the dielectric layer is grown is polished on the front side to obtain a substrate after the front side is polished.

[0048] In some embodiments, the gallium oxide single crystal substrate prepared with the dielectric layer is polished on the front side to obtain a gallium oxide single crystal substrate with high surface quality.

[0049] In some embodiments, the front side polishing method is to polish the front side of the gallium oxide single crystal substrate using a single side polisher. The polishing pressure ranges from 100 to 350 g / cm2, and the rotation speed ranges from 60 to 120 rpm. The particle size of the silica sol polishing liquid used for polishing ranges from 50 to 150 nm, the flow rate of the polishing liquid ranges from 10 to 50 mL / min, and the polishing time ranges from 30 to 120 min.

[0050] It should be noted that in steps 201 and 202, the advantage of preparing the dielectric layer first and then polishing the front side is that secondary processing is avoided due to contamination or scratches on the front side of the gallium oxide single crystal substrate when preparing the dielectric layer.

[0051] Step 203 , under the protection of the dielectric layer, gallium oxide homoepitaxial growth is performed on the front side of the substrate after front side polishing to obtain a homoepitaxial growth substrate.

[0052] In some embodiments, the gallium oxide homoepitaxy method includes halide vapor phase epitaxy, metal organic chemical vapor deposition, or low pressure chemical vapor deposition.

[0053] In some embodiments, the growth temperature of gallium oxide homoepitaxial growth is in a range of 950 to 1100° C., and the oxygen flow rate is in a range of 30 to 500 mL / min.

[0054] In some embodiments, the gallium oxide single crystal substrate obtained in step 202 is placed in a HVPE furnace chamber for homoepitaxial growth of gallium oxide, and the thickness of the epitaxial layer growth ranges from 10 to 30 μm. The preparation method is to use HVPE equipment to perform homoepitaxial growth of gallium oxide, the growth pressure ranges from 100 to 1000 mbar, the growth temperature ranges from 950 to 1100° C., nitrogen is used as a carrier gas, the total flow ranges from 5000 to 10000 L / min, the oxygen flow ranges from 30 to 500 mL / min, the chlorine or hydrogen chloride flow ranges from 10 to 100 mL / min, and the growth time ranges from 60 to 180 min.

[0055] In some embodiments, the gallium oxide homoepitaxial layer is a lightly doped epitaxial layer. For example, the doping concentration is generally 1E16 cm -3 Order of magnitude.

[0056] Step 204 , removing the dielectric layer on the back side of the homoepitaxially grown substrate to obtain a substrate with the back side dielectric layer removed.

[0057] In some embodiments, removing the dielectric layer on the back side of the homoepitaxial substrate to obtain the substrate without the back side dielectric layer includes: removing the dielectric layer on the back side of the homoepitaxial substrate by a grinding process to obtain the substrate without the back side dielectric layer.

[0058] In some embodiments, the gallium oxide epitaxial wafer (ie, homoepitaxial substrate) obtained in step 203 is subjected to secondary processing, and the back side may be ground to remove the dielectric layer.

[0059] Exemplarily, the back grinding process is as follows: a single-sided grinder is used to grind the back side of the gallium oxide epitaxial wafer at a pressure ranging from 50 to 300 g / cm 2 , the rotation speed ranges from 20 to 70 rpm, the particle size range of the diamond grinding liquid used is 0.5 to 3 μm, and the grinding time ranges from 10 to 50 min.

[0060] It should also be noted that the back dielectric layer can prevent the generation of excess polycrystalline gallium oxide on the back during homoepitaxial growth in step 203, thereby reducing the back roughness. Furthermore, grinding and polishing of the back can be avoided. For example, a wet etching process can be used to remove the dielectric layer in step 204, thereby avoiding grinding and polishing of the back after epitaxy. The efficiency of wet etching is much greater than that of grinding and polishing, so the overall preparation efficiency is greatly improved.

[0061] Step 205 , polishing the front side of the substrate with the back dielectric layer removed to obtain a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate.

[0062] In some embodiments, the front side of the substrate with the back dielectric layer removed is polished to remove the gallium oxide epitaxial morphology, thereby obtaining a gallium oxide homoepitaxial wafer with high surface quality.

[0063] Exemplarily, the front side polishing process of the gallium oxide epitaxial wafer is as follows: a single-side polishing machine is used to polish the front side of the gallium oxide single crystal substrate at a pressure ranging from 100 to 350 g / cm 2 , the rotation speed range is 60 to 120rpm, the particle size range of the silica sol polishing liquid used is 50 to 150nm, the flow rate range of the polishing liquid is 10 to 50mL / min, and the polishing time range is 30 to 120min.

[0064] The embodiment of the present invention grows a dielectric layer on the back side of the substrate before gallium oxide homoepitaxial growth, and performs gallium oxide homoepitaxial growth under the protection of the dielectric layer, so that high-temperature oxygen can be isolated from the back side of the substrate during the epitaxial growth, reducing the contact between the back side of the gallium oxide single crystal substrate and the high-temperature oxygen, and can effectively ensure that the resistivity of the gallium oxide single crystal substrate is not affected by oxygen during the epitaxial growth process, thereby solving the problem of increased substrate resistivity after gallium oxide homoepitaxial growth.

[0065] In addition, under the protection of the dielectric layer, the generation of polycrystalline gallium oxide on the back side of the gallium oxide single crystal substrate can be avoided, reducing the damage to the back side caused by homoepitaxial growth. At the same time, the back dielectric layer can be removed by back polishing after epitaxy in the normal process, which has little impact on the original process efficiency.

[0066] Third, growing the back dielectric layer before homoepitaxial growth and before polishing the front surface can also avoid contamination or scratching of the polishing surface during the growth of the dielectric layer. At the same time, the back dielectric layer can also protect the back surface during polishing the front surface.

[0067] The above steps are described below using a comprehensive embodiment. The embodiment of the present invention may adopt the following technical solutions, including:

[0068] Step (1) selecting an n-type gallium oxide single crystal substrate, which is in a stage where the upper and lower surfaces have been ground but not polished.

[0069] Step (2) cleaning the gallium oxide single crystal substrate by sequentially using a dewaxing solution, ethanol, and deionized water for ultrasonic cleaning, with each cleaning time being 5-20 minutes.

[0070] Step (3) prepares a dielectric layer on the back of the cleaned gallium oxide single crystal substrate. The dielectric layer is made of SiO2, SiNx or Al2O3 with a thickness of 50-1000 nm. The dielectric layer is prepared by one of magnetron sputtering, thermal evaporation and plasma enhanced chemical vapor deposition.

[0071] Step (4) polishing the front side of the gallium oxide single crystal substrate having the dielectric layer.

[0072] Step (5) placing the gallium oxide single crystal substrate with a dielectric layer on the back side in step (4) into an epitaxial furnace chamber for epitaxial growth to obtain a gallium oxide homoepitaxial wafer; the epitaxial growth method may be any one of halide vapor phase epitaxy, metal organic chemical vapor deposition, and low pressure chemical vapor deposition.

[0073] Step (6) processes the gallium oxide homoepitaxial wafer prepared in step (5), removes the dielectric layer on the back side by a grinding process, and polishes the front side to obtain a gallium oxide homoepitaxial wafer with high surface quality.

[0074] In the embodiment of the present invention, based on the conventional process, a dielectric layer is first prepared before polishing the gallium oxide single crystal substrate, and then the front surface of the gallium oxide single crystal wafer is polished, epitaxially grown, the dielectric layer is removed and the front surface is polished in sequence to obtain a HVPE gallium oxide homoepitaxial wafer with high surface quality.

[0075] The embodiment of the present invention prepares a dielectric layer on the back of the gallium oxide single crystal substrate, effectively reducing the influence of oxygen on the electrical properties of the gallium oxide single crystal substrate, which is beneficial to improving the electrical properties of the gallium oxide homoepitaxial wafer, and ultimately improving the performance of the gallium oxide device. The embodiment of the present invention first performs step (3) and then performs steps (4) and (5), which can effectively avoid damage and contamination to the polished surface of the gallium oxide single crystal substrate when preparing the dielectric layer, and can also avoid repeated processing of the substrate.

[0076] Figure 3 These are the resistivity test results of gallium oxide homoepitaxial wafers prepared without a dielectric layer. Figure 4 These are the resistivity test results of gallium oxide homoepitaxial wafers prepared with an additional dielectric layer. Figure 3 , Figure 4 Different colors represent different resistivity. For example, red represents the highest resistivity, and blue represents the lowest resistivity. Figure 3 and Figure 4 The overall resistivity difference is one order of magnitude. Figure 3 and Figure 4 The same color does not mean the same resistivity. Figure 3 and Figure 4 The resistivity of the embodiment of the present invention is significantly reduced by one order of magnitude compared to that before improvement.

[0077] An embodiment of the present invention provides a homoepitaxial wafer of an n-type gallium oxide single crystal substrate, which is prepared based on any of the above methods for preparing a homoepitaxial wafer of an n-type gallium oxide single crystal substrate.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate, characterized in that: include: Growing a dielectric layer on the back side of the n-type gallium oxide single crystal substrate to cover the entire back side of the substrate to obtain a substrate after the dielectric layer is grown; Under the protection of the dielectric layer, the substrate after the growth of the dielectric layer is polished on the front side to obtain a substrate after the front side is polished; Under the protection of the dielectric layer, gallium oxide homoepitaxial growth is performed on the front side of the substrate after front side polishing to obtain a homoepitaxial substrate; wherein, during the gallium oxide homoepitaxial growth, oxygen is introduced to provide oxygen elements for gallium oxide growth; Removing the dielectric layer on the back side of the homoepitaxial substrate to obtain a substrate without the back side dielectric layer; The substrate with the back dielectric layer removed is polished on the front side to obtain a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate.

2. The method for preparing a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate according to claim 1, characterized in that: The step of removing the dielectric layer on the back side of the homoepitaxial substrate to obtain the substrate without the back side dielectric layer comprises: The dielectric layer on the back side of the homoepitaxial substrate is removed by a grinding process to obtain a substrate with the back side dielectric layer removed.

3. The method for preparing a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate according to claim 1, characterized in that: The material of the dielectric layer includes silicon oxide, silicon nitride or aluminum oxide.

4. The method for preparing a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate according to claim 1, characterized in that: The thickness of the dielectric layer ranges from 50 to 1000 nanometers.

5. The method for preparing a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate according to claim 1, characterized in that: The method of growing the dielectric layer on the back side of the n-type gallium oxide single crystal substrate includes magnetron sputtering, thermal evaporation or plasma enhanced chemical vapor deposition.

6. The method for preparing a homoepitaxial wafer of an n-type gallium oxide single crystal substrate according to claim 1, characterized in that: The gallium oxide homoepitaxial growth method includes halide vapor phase epitaxy, metal organic chemical vapor deposition or low pressure chemical vapor deposition.

7. The method for preparing a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate according to claim 6, characterized in that: The growth temperature of the gallium oxide homoepitaxial growth is in the range of 950 to 1100° C., and the oxygen flow rate is in the range of 30 to 500 mL / min.

8. The method for preparing a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate according to claim 1, characterized in that: The n-type gallium oxide single crystal substrate is a heavily doped substrate.

9. The method for preparing a homoepitaxial wafer of an n-type gallium oxide single crystal substrate according to claim 8, characterized in that: The doping concentration of the n-type gallium oxide single crystal substrate is greater than 1E18cm -3 , resistivity is less than 0.04Ω·cm.

10. A homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate, characterized in that: The homoepitaxial wafer is prepared based on the method for preparing a homogeneous epitaxial wafer of an n-type gallium oxide single crystal substrate according to any one of claims 1 to 9.

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