CN111128688A - Method for manufacturing n-type gallium nitride self-supporting substrate - Google Patents
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Abstract
The invention provides a method for manufacturing an n-type gallium nitride self-supporting substrate, which comprises the following steps: forming a gallium nitride template layer and a non-doped gallium nitride layer on a sapphire substrate; stripping the sapphire substrate to obtain a non-doped thin gallium nitride self-supporting substrate; 4) removing the bottom layer part with the worst crystal quality in the non-doped thin gallium nitride self-supporting substrate; epitaxially growing an n-type gallium nitride layer on the undoped thin gallium nitride self-supporting substrate to obtain an n-type thick gallium nitride self-supporting substrate; removing the undoped layer at the bottom of the n-type thick gallium nitride self-supporting substrate; and grinding and polishing the n-type thick gallium nitride self-supporting substrate to obtain the n-type gallium nitride self-supporting substrate. According to the manufacturing method of the n-type gallium nitride self-supporting substrate, under the condition that the n-type thick gallium nitride self-supporting substrate has warpage of different degrees, the undoped layer at the bottom of the n-type thick gallium nitride self-supporting substrate can be completely removed, and the n-type gallium nitride self-supporting substrate is obtained.
Description
Technical Field
The invention belongs to the field of semiconductor material manufacturing, and particularly relates to a manufacturing method of an n-type gallium nitride self-supporting substrate.
Background
In order to realize the preparation of electronic and electric devices with excellent performances such as high frequency, high efficiency, high power and the like, the development of third-generation wide bandgap semiconductor materials represented by gallium nitride is accelerated at the end of the twentieth century. Due to its excellent properties, gallium nitride (GaN) can be widely studied and applied in the preparation of semiconductor devices operating under other special conditions, such as high-power high-frequency devices. The crystal quality of the GaN epitaxial layer is the fundamental guarantee for realizing high-performance GaN-based devices. The adoption of the GaN single crystal substrate to realize homoepitaxy is a main way for improving the crystal quality of the GaN epitaxial layer and a GaN-based device.
Currently, blue-green laser diodes and vertical structure gallium nitride power electronic devices require n-type gallium nitride free-standing substrates. The current preparation method comprises the steps of firstly growing a non-doped gallium nitride thick film in an epitaxial mode, then removing a substrate through a laser stripping method, then homoepitaxially growing an n-type gallium nitride thick film on the non-doped gallium nitride thick film, and finally removing the non-doped thick film layer through a grinding and polishing method, so that the n-type gallium nitride self-supporting substrate is obtained. In the above process, the undoped gan thick film is grown at the initial stage because the yield of the n-type gan thick film grown at the initial stage is low, and it is difficult to ensure that the n-type gan thick film does not crack. This results from the modification of the stress within the film layer caused by the introduction of dopant atoms (Si or Ge). In addition, in the polishing step, since the free-standing substrate is warped, it is difficult to completely remove the undoped layer in order to secure the thickness of the obtained substrate.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method for fabricating an n-type gan self-supporting substrate, which is used to solve the problem of incomplete removal of undoped layer in the prior art and improve the overall yield of fabrication.
To achieve the above and other related objects, the present invention provides a method for fabricating an n-type gan self-standing substrate, the method comprising the steps of: 1) providing a sapphire substrate, and forming a gallium nitride template layer on the sapphire substrate; 2) epitaxially growing an undoped gallium nitride layer on the gallium nitride template layer; 3) separating the sapphire substrate from the gallium nitride template layer by using a laser lift-off process to obtain a non-doped thin gallium nitride self-supporting substrate; 4) removing the bottom layer part with the worst crystal quality in the non-doped thin gallium nitride self-supporting substrate; 5) epitaxially growing an n-type gallium nitride layer on the undoped thin gallium nitride self-supporting substrate to obtain an n-type thick gallium nitride self-supporting substrate; 6) removing the undoped layer at the bottom of the n-type thick gallium nitride self-supporting substrate; 7) and polishing the n-type thick gallium nitride self-supporting substrate to obtain the n-type gallium nitride self-supporting substrate.
Optionally, step 1) depositing the gallium nitride template layer by using a Metal Organic Chemical Vapor Deposition (MOCVD) process, wherein the thickness of the gallium nitride template layer is between 2 and 10 micrometers.
Optionally, in the step 2), Hydride Vapor Phase Epitaxy (HVPE) process is adopted to perform epitaxial growth on the gallium nitride template layer, so as to form the undoped gallium nitride layer, where the thickness of the undoped gallium nitride layer is between 100 micrometers and 450 micrometers.
Optionally, in step 4), the bottom layer part with the worst crystal quality in the non-doped thin gallium nitride self-supporting substrate is removed by a physical method or a chemical method, the thickness of the removed bottom layer part is between 50 micrometers and 220 micrometers, and in step 6), the non-doped thin gallium nitride self-supporting substrate at the bottom of the n-type thick gallium nitride self-supporting substrate is removed by a physical method or a chemical method, and the thickness of the removed bottom layer part is between 50 micrometers and 220 micrometers.
Optionally, the removing rate of the bottom layer part in the steps 4) and 6) is between 20 microns/hour and 100 microns/hour.
Optionally, the physical method in step 4) and step 6) includes one of laser ablation removal and plasma etching, and the chemical method includes one of phosphoric acid etching and alkali etching.
Optionally, the laser used for laser ablation includes one of a gas laser, a solid-state laser, and a semiconductor laser.
Optionally, the laser power is 0.1-15W.
Optionally, the etching gas used for plasma etching includes Cl2And BCl3。
Optionally, before the chemical method is performed to remove the bottom layer portion, a step of forming an etching protection layer on an upper surface of the undoped thin gan self-supporting substrate or the n-type thick gan self-supporting substrate is further included.
Optionally, in step 5), a hydride vapor phase epitaxy process is used to perform epitaxial growth on the undoped thin gallium nitride self-supporting substrate to form the n-type gallium nitride layer, where the thickness of the n-type gallium nitride layer is between 400 micrometers and 1000 micrometers.
Optionally, in step 7), polishing the n-type thick gallium nitride self-supporting substrate for multiple times by using a grinding and polishing device, and then performing edge cutting and chamfering treatment to obtain the n-type gallium nitride self-supporting substrate, wherein the thickness range of the n-type gallium nitride self-supporting substrate is between 300 micrometers and 1000 micrometers.
As described above, the method for manufacturing an n-type gan self-supporting substrate according to the present invention has the following advantages:
according to the manufacturing method of the n-type gallium nitride self-supporting substrate, under the condition that the n-type thick gallium nitride self-supporting substrate has warpage of different degrees, the undoped layer at the bottom of the n-type thick gallium nitride self-supporting substrate can be completely removed, and the n-type gallium nitride self-supporting substrate is obtained.
The invention manufactures the n-type gallium nitride self-supporting substrate suitable for industrial production by configuring the epitaxial thickness and removing the thickness in each step, and has wide application prospect in the field of manufacturing semiconductor materials and devices.
Drawings
Fig. 1 to 8 are schematic structural views showing steps of the method for manufacturing an n-type gan self-standing substrate according to the present invention.
Description of the element reference numerals
101 sapphire substrate
102 gallium nitride template layer
103 undoped gallium nitride layer
1031 bottom layer part
1032 Top layer portion
104 n-type gallium nitride layer
201 acid-resistant photoresist
301 alkali-resistant photoresist
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.
In the context of this application, a structure described as having a first feature "on" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.
It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
During the epitaxial growth of n-type gallium nitride, there is stress in the epitaxial film, which is mainly lattice mismatch stress and thermal mismatch stress. Lattice mismatch stress is mainly caused by lattice distortion caused by the mismatch of lattice constants of the sapphire substrate and the gallium nitride crystal and the introduction of doping atoms; the thermal mismatch stress is mainly caused by different thermal expansion coefficients of the two, the gallium nitride epitaxial wafer grows at a high temperature of more than 800 ℃, and after the growth is finished and the temperature is reduced, the contraction ratios of crystal lattices of the two are greatly different, so that the crystal lattices are mutually drawn. In order to reduce the influence of stress, the initial stage of the epitaxial growth of the n-type gallium nitride grows an undoped gallium nitride thick film layer, and finally the undoped gallium nitride thick film layer is removed by grinding and polishing. However, the n-type gan self-supporting substrate before grinding and polishing may warp to different degrees under the stress, so that the undoped gan thick film layer is often difficult to be completely removed by grinding and polishing. To completely remove the non-doped gallium nitride thick film layer, a greater thickness needs to be removed, so that the resulting free-standing substrate is thinner. To obtain an n-type GaN self-supporting substrate with a sufficient thickness, the thickened n-type GaN self-supporting substrate is prone to cracking under stress before grinding and polishing.
In order to solve the above problem, the present embodiment provides a method for manufacturing an n-type gan self-supporting substrate, the method comprising the following steps:
step 1), providing a sapphire substrate, and forming a gallium nitride template layer on the sapphire substrate; for example, the gallium nitride template layer may be deposited using a metal organic chemical vapor deposition process, the gallium nitride template layer having a thickness between 2 microns and 10 microns.
And 2) epitaxially growing an undoped gallium nitride layer on the gallium nitride template layer. For example, the undoped gallium nitride layer may be formed by performing an epitaxial growth on the gallium nitride template layer by using a hydride vapor phase epitaxy process, and the thickness of the undoped gallium nitride layer is between 100 micrometers and 450 micrometers.
Step 3), separating the sapphire substrate from the gallium nitride template layer by utilizing a laser stripping process to obtain a non-doped thin gallium nitride self-supporting substrate;
and 4) removing the bottom layer part with the worst crystal quality in the undoped thin gallium nitride self-supporting substrate. For example, the bottom layer part with the worst crystal quality in the undoped thin gallium nitride self-supporting substrate can be removed by a physical method or a chemical method, and the thickness of the removed bottom layer part is between 50 microns and 220 microns. The removal rate of the bottom layer portion is between 20 microns/hour and 100 microns/hour.
Specifically, the physical method comprises one of laser ablation removal and plasma etching, and the chemical method comprises one of phosphoric acid etching and alkali etching. The laser used for laser ablation comprises one of a gas laser, a solid laser and a semiconductor laser. The power of the laser is 0.1-15W. The etching gas selected for plasma etching comprises Cl2And BCl3。
Specifically, if a chemical method is adopted, before the chemical method is performed to remove the bottom layer part, a step of forming an etching protection layer on the upper surface of the undoped thin gallium nitride self-supporting substrate is further included.
And 5) epitaxially growing an n-type gallium nitride layer on the undoped thin gallium nitride self-supporting substrate to obtain an n-type thick gallium nitride self-supporting substrate. For example, the n-type gallium nitride layer may be formed by performing epitaxial growth on the undoped thin gallium nitride self-supporting substrate by using a hydride vapor phase epitaxy process, and the thickness of the n-type gallium nitride layer is between 400 microns and 1000 microns.
Step 6), removing the undoped layer at the bottom of the n-type thick gallium nitride self-supporting substrate; for example, the undoped layer at the bottom of the n-type thick gallium nitride self-supporting substrate is removed by a physical method or a chemical method, and the thickness of the removed undoped layer is between 50 microns and 220 microns. The removal rate of the undoped layer is between 20 microns/hour and 100 microns/hour.
Specifically, the physical method comprises one of laser ablation removal and plasma etching, and the chemical method comprises one of phosphoric acid etching and alkali etching. The laser used for laser ablation comprises one of a gas laser, a solid laser and a semiconductor laser. The power of the laser is 0.1-15W. The etching gas selected for plasma etching comprises Cl2And BCl3。
Specifically, if a chemical method is adopted, before the non-doped layer is removed by the chemical method, the method further comprises the step of forming an etching protection layer on the upper surface of the n-type thick gallium nitride self-supporting substrate.
And 7) polishing the n-type thick gallium nitride self-supporting substrate to obtain the n-type gallium nitride self-supporting substrate. For example, the n-type thick gan self-supporting substrate may be polished by a grinding and polishing device for multiple times, and then trimmed and chamfered to obtain the n-type gan self-supporting substrate, wherein the thickness of the n-type gan self-supporting substrate ranges from 300 micrometers to 1000 micrometers.
In one specific implementation, as shown in fig. 1 to 8, the method for manufacturing an n-type gan self-supporting substrate includes the steps of:
as shown in fig. 1, step 1) is first performed to provide a sapphire substrate 101, and gallium nitride with a thickness of 4 microns to 6 microns is epitaxially grown on the sapphire substrate 101 by MOCVD, so as to serve as a gallium nitride template layer 102 to be subsequently grown.
As shown in fig. 2, step 2) is then performed, and a non-doped gallium nitride layer 103 with a total epitaxial thickness of 150-450 μm is epitaxially formed on the gallium nitride template layer 102 by using a Hydride Vapor Phase Epitaxy (HVPE) process, so as to obtain a sapphire/gallium nitride composite substrate.
As shown in fig. 3, step 3) is followed by Laser lift-off (LLO): and (2) turning over the sapphire/gallium nitride composite substrate to enable the sapphire substrate 101 to face upwards, and irradiating a sapphire/gallium nitride interface by using a laser at a high temperature of 800 ℃ in a nitrogen atmosphere to separate the sapphire substrate from gallium nitride in the sapphire/gallium nitride composite substrate to obtain a non-doped thin gallium nitride self-supporting substrate which comprises a gallium nitride template layer 102 and a non-doped gallium nitride layer 103.
The laser is one of a gas laser, a solid laser and a semiconductor laser, and the wavelength of the laser can be 355 nanometers or 266 nanometers.
As shown in fig. 4 to 6, step 4) is then performed, and the bottom layer portion with the worst crystal quality in the undoped thin gan self-supporting substrate is removed by a physical method or a chemical method.
In one embodiment, as shown in FIG. 4, the thin undoped GaN self-supporting substrate obtained in 3) is removed by a laser to remove the portion with the worst crystal quality, the removed portion includes the template layer 102 of GaN layer and the bottom portion 1031 of the undoped GaN layer, the total thickness of the removed portions is 50-220 μm, the removal rate is 20-100 μm/hr, for example, 20 μm/hr, the remaining GaN layer portion includes the top portion 1032 of the undoped GaN layer, and during this process, the template layer 102 of GaN is ablated before the bottom portion 1031 of the undoped GaN layer. In the embodiment, the laser is adopted to remove the part with the worst crystal quality in the thin gallium nitride self-supporting substrate, and the method has the advantages of simple process, low process cost and high process efficiency.
Wherein, the laser is one of gas laser, solid laser and semiconductor laser. The wavelength of the laser is less than or equal to 10.8 microns, and the power of the laser is 1-10W.
In another embodiment, as shown in fig. 4, the thin undoped gallium nitride template layer 102 obtained in 3) is removed from the substrate with the worst crystal quality by inductively coupled plasma etching (ICP etching), the removed portion includes the gallium nitride layer template layer 102 and the bottom portion 1031 of the undoped gallium nitride layer, the total thickness of the removed portions is 50-220 μm, the removal rate is 20-100 μm/hr, for example, 20 μm/hr, the remaining gallium nitride layer portion includes the top portion 1032 of the undoped gallium nitride layer, and during this process, the gallium nitride template layer 102 is etched before the bottom portion 1031 of the undoped gallium nitride layer. WhereinThe ICP etching can adopt Cl2And BCl3Is an etching gas. In the embodiment, the part with the worst crystal quality in the thin gallium nitride self-supporting substrate is removed by adopting an inductively coupled plasma etching method (ICP etching), and the method has the advantages of high process precision, basically no residue and the like.
In a further embodiment, the portion of the undoped thin gallium nitride free-standing substrate resulting from step 3) having the worst crystal quality is removed using hot phosphoric acid. First, as shown in fig. 5, an acid-resistant photoresist 201 with a certain thickness is spin-coated on the surface of the undoped gallium nitride layer 103 of the undoped thin gallium nitride self-supporting substrate, and the whole is developed, so that the surface is not affected by the subsequent chemical etching process, for example, the acid-resistant photoresist 201 may be a positive photoresist or a negative photoresist with a thickness greater than 2 microns, so as to ensure the protection effect. Next, the undoped thin gan free-standing substrate is immersed in a hot phosphoric acid solution to remove the portion with the worst crystal quality, the removed portion includes the gan template layer 102 and the bottom portion 1031 of the undoped gan layer, the total thickness of the removal is 50-220 μm, the removal rate is 20-100 μm/hr, for example, 50 μm/hr, the remaining gan layer portion includes the top portion 1032 of the undoped gan layer, and in this process, the gan template layer 102 is etched away before the bottom portion 1031 of the undoped gan layer. Wherein the temperature of the hot phosphoric acid is more than 100 ℃, and the mass concentration is 70-90%. In the embodiment, the hot phosphoric acid solution is adopted to remove the part with the worst crystal quality, so that the removal rate is very high, and the overall process efficiency can be greatly improved.
In another embodiment, the portion of the undoped thin gallium nitride obtained in 3) that is the worst quality crystal is removed from the free-standing substrate using thermal potassium hydroxide. First, as shown in fig. 6, an alkali-resistant photoresist 301 with a certain thickness is spin-coated on the surface of the undoped gallium nitride layer 103 of the undoped thin gallium nitride self-supporting substrate, and the entire surface is developed, so that the surface is not affected by the subsequent chemical etching process, for example, the alkali-resistant photoresist 301 may be a positive photoresist or a negative photoresist with a thickness greater than 2 μm, so as to ensure the protection effect. Next, the undoped thin gan freestanding substrate is immersed in a koh solution to remove the portion with the worst crystal quality, the removed portion includes the gan template layer 102 and the bottom portion 1031 of the undoped gan layer, the total thickness of the removal is 50-220 μm, the removal rate is 20-100 μm/hr, for example, 50 μm/hr, the top portion 1032 of the undoped gan layer remains, and during this process, the gan template layer 102 is etched away before the bottom portion 1031 of the undoped gan layer. Wherein the temperature of the potassium hydroxide is more than 60 ℃, and the molar concentration is 1-3 mol/L. In the embodiment, the potassium hydroxide solution is adopted to remove the part with the worst crystal quality, so that the removal rate is very high, and the overall process efficiency can be greatly improved.
By removing the bottom layer part with the worst crystal quality, the stress in the remained undoped thin gallium nitride self-supporting substrate can be greatly reduced, so that the dislocation density can be effectively reduced in the subsequent epitaxial thickening process, the stress of the undoped thin gallium nitride self-supporting substrate is reduced, and the cracking rate in the subsequent epitaxial thickening process is reduced.
Then, step 5) is performed, as shown in fig. 7, an n-type gallium nitride layer 104 is epitaxially grown on the undoped thin gallium nitride free-standing substrate obtained in step 4), so as to obtain an n-type thick gallium nitride free-standing substrate, for example, an hydride vapor phase epitaxy process may be performed on the undoped thin gallium nitride free-standing substrate to perform epitaxial growth, so as to form the n-type gallium nitride layer, where the thickness of the n-type gallium nitride layer is between 400 micrometers and 1000 micrometers. Optionally, the dopant in the n-type gallium nitride layer contains atomic silicon or germanium.
Then, step 6) is carried out, the undoped layer at the bottom of the n-type thick gallium nitride self-supporting substrate is removed by a physical method or a chemical method, the thickness of the removed undoped layer is between 50 microns and 220 microns, and as shown in fig. 8, the n-type gallium nitride layer 104 is remained. The removal method is as described in step 4), and will not be described here.
Optionally, the removed undoped layer is a top layer portion 1032 of the undoped gallium nitride layer. Of course, in a specific implementation, the removed n-type gallium nitride layer 104 may also be included in a small amount to ensure absolute removal of the undoped layer.
And 7), grinding and polishing the n-type gallium nitride thick self-supporting substrate for multiple times to obtain the final n-type gallium nitride self-supporting substrate. For example, the n-type thick gan self-supporting substrate may be subjected to multiple times of grinding and polishing by a grinding and polishing device, and then subjected to edge cutting and chamfering treatment to obtain a final n-type gan self-supporting substrate, wherein the thickness of the final gan self-supporting substrate ranges from 300 micrometers to 1000 micrometers.
As described above, the method for manufacturing an n-type gan self-supporting substrate according to the present invention has the following advantages:
according to the manufacturing method of the n-type gallium nitride self-supporting substrate, under the condition that the n-type thick gallium nitride self-supporting substrate has warpage of different degrees, the undoped layer at the bottom of the n-type thick gallium nitride self-supporting substrate can be completely removed, and the n-type gallium nitride self-supporting substrate is obtained.
The invention manufactures the n-type gallium nitride self-supporting substrate suitable for industrial production by configuring the epitaxial thickness and removing the thickness in each step, and has wide application prospect in the field of manufacturing semiconductor materials and devices.
Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (12)
1. A method for manufacturing an n-type gallium nitride self-supporting substrate is characterized by comprising the following steps:
1) providing a sapphire substrate, and forming a gallium nitride template layer on the sapphire substrate;
2) epitaxially growing an undoped gallium nitride layer on the gallium nitride template layer;
3) separating the sapphire substrate from the gallium nitride template layer by using a laser lift-off process to obtain a non-doped thin gallium nitride self-supporting substrate;
4) removing the bottom layer part with the worst crystal quality in the non-doped thin gallium nitride self-supporting substrate;
5) epitaxially growing an n-type gallium nitride layer on the undoped thin gallium nitride self-supporting substrate to obtain an n-type thick gallium nitride self-supporting substrate;
6) removing the undoped layer at the bottom of the n-type thick gallium nitride self-supporting substrate;
7) and grinding and polishing the n-type thick gallium nitride self-supporting substrate to obtain the n-type gallium nitride self-supporting substrate.
2. The method for manufacturing an n-type GaN self-supporting substrate according to claim 1, wherein: step 1) depositing the gallium nitride template layer by utilizing a metal organic chemical vapor deposition process, wherein the thickness of the gallium nitride template layer is between 2 and 10 micrometers.
3. The method for manufacturing an n-type GaN self-supporting substrate according to claim 1, wherein: and 2) carrying out epitaxial growth on the gallium nitride template layer by adopting a hydride vapor phase epitaxy process to form the non-doped gallium nitride layer, wherein the thickness of the non-doped gallium nitride layer is between 100 and 450 microns.
4. The method for manufacturing an n-type GaN self-supporting substrate according to claim 3, wherein: and step 4) removing the bottom layer part with the worst crystal quality in the non-doped thin gallium nitride self-supporting substrate by adopting a physical method or a chemical method, wherein the thickness of the removed bottom layer part is between 50 microns and 220 microns, and step 6) removing the non-doped layer at the bottom of the n-type thick gallium nitride self-supporting substrate by adopting a physical method or a chemical method, wherein the thickness of the removed bottom layer part is between 50 microns and 220 microns.
5. The method for manufacturing an n-type GaN self-supporting substrate according to claim 4, wherein: the removal rate of the bottom layer part removed in the steps 4) and 6) is between 20 microns/hour and 100 microns/hour.
6. The method for manufacturing an n-type GaN self-supporting substrate according to claim 4, wherein: the physical method in the steps 4) and 6) comprises one of laser ablation removal and plasma etching, and the chemical method comprises one of phosphoric acid corrosion and alkali corrosion.
7. The method of claim 6, wherein: the laser used for laser ablation comprises one of a gas laser, a solid laser and a semiconductor laser.
8. The method for manufacturing an n-type GaN self-supporting substrate according to claim 7, wherein: the power of the laser is 0.1-15W.
9. The method of claim 6, wherein: the etching gas selected for plasma etching comprises Cl2And BCl3。
10. The method for manufacturing an n-type GaN self-supporting substrate according to claim 4, wherein: before the chemical method is carried out to remove the bottom layer part, the method also comprises the step of forming an etching protection layer on the upper surface of the non-doped thin gallium nitride self-supporting substrate or the n-type thick gallium nitride self-supporting substrate.
11. The method for manufacturing an n-type GaN self-supporting substrate according to claim 1, wherein: and 5) carrying out epitaxial growth on the non-doped thin gallium nitride self-supporting substrate by adopting a hydride vapor phase epitaxy process to form the n-type gallium nitride layer, wherein the thickness of the n-type gallium nitride layer is between 400 and 1000 microns.
12. The method for manufacturing an n-type GaN self-supporting substrate according to claim 1, wherein: and 7) grinding and polishing the n-type thick gallium nitride self-supporting substrate for multiple times by using grinding and polishing equipment, and then performing edge cutting and chamfering treatment to obtain the n-type gallium nitride self-supporting substrate, wherein the thickness range of the n-type gallium nitride self-supporting substrate is 300-1000 microns.
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