Gallium nitride substrate, method of manufacturing the same, and method of manufacturing semiconductor device

Abstract

The application discloses a method for manufacturing a gallium nitride substrate, comprising: alternately growing N first low-temperature gallium nitride layers and N second high-temperature gallium nitride layers on a gallium nitride template from bottom to top to form a first epitaxial layer, the first low-temperature gallium nitride layer is a silicon-doped gallium nitride film grown in a low-temperature range, and the second high-temperature gallium nitride layer is an undoped gallium nitride film grown in a high-temperature range; stripping a growth substrate of the gallium nitride template; electrochemically etching the first epitaxial layer, each first low-temperature gallium nitride layer is etched to have a hole structure, so that the first epitaxial layer is etched into a porous gallium nitride thick film; and growing a third low-temperature gallium nitride layer and a doped fourth high-temperature gallium nitride layer on the uppermost second high-temperature gallium nitride layer to form a non-porous gallium nitride thick film. The application provides a homogenized gallium nitride substrate, and reduces the size of negative warping caused by temperature difference between upper and lower surfaces of the growth substrate. The application further discloses a method for manufacturing a semiconductor device and the gallium nitride substrate.

Description

[0001] Gallium nitride substrates, their fabrication methods, and semiconductor device fabrication methods Technical Field

[0002] This invention relates to the field of semiconductor growth substrate materials, and more specifically to the structure and preparation method of a gallium nitride substrate. Background Technology

[0003] Although GaN single-crystal growth substrates have disadvantages in terms of price and size, GaN layers epitaxially grown on homogeneous substrates have a much lower defect density than GaN layers epitaxially grown on heterogeneous substrates (Si, SiC). For example, the dislocation density of heteroepitaxial GaN on a Si growth substrate is typically around 1E9 cm⁻¹. -2 Nearby, while the dislocation density of epitaxial GaN on GaN self-supporting substrates typically decreases to 1E6 cm⁻¹. -2 Therefore, whether it's laser chips or power and radio frequency devices, GaN single crystal growth substrates will be the optimal, or even the only, choice for high-performance, high-stability, high-end products.

[0004] On the one hand, commercially available GaN self-supporting substrates are mostly grown using HVPE epitaxy followed by polishing. Due to technological and cost limitations, the thickness of GaN growth substrates is relatively small, typically around 500 μm. On the other hand, the chip fabrication processes for RF and power devices are often carried out at "large" sizes of 4-8 inches. However, during the epitaxial growth of large-size, thin-grown GaN substrates, significant negative warpage can occur due to temperature differences. This affects the thickness and composition of the epitaxial film, consequently impacting the consistency of device performance, which is often unacceptable in the industrialization of devices.

[0005] Therefore, there is an urgent need for a method and structure for fabricating gallium nitride substrates that can solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method for fabricating a gallium nitride substrate, and to provide a homogeneous gallium nitride substrate that reduces negative warpage caused by temperature differences between the upper and lower surfaces of the growth substrate.

[0007] To achieve the above objectives, the present invention provides a method for fabricating a gallium nitride (GaN) substrate, comprising: sequentially and alternately growing N first low-temperature GaN layers and N second high-temperature GaN layers from bottom to top on a GaN template to form a first epitaxial layer, wherein the GaN template includes a growth substrate, the first low-temperature GaN layers are silicon-doped GaN films grown in a low-temperature range, and the second high-temperature GaN layers are undoped GaN films grown in a high-temperature range, where N is 1 or an integer greater than or equal to 2; stripping the growth substrate from the GaN template; and electrochemical etching. In the first epitaxial layer, when current flows through the silicon-doped first low-temperature gallium nitride layer, etched holes are formed where silicon impurities accumulate, thus etching a porous structure into each of the first low-temperature gallium nitride layers, resulting in a porous gallium nitride thick film. On the uppermost second high-temperature gallium nitride layer of the porous gallium nitride thick film, a third low-temperature gallium nitride layer and a fourth high-temperature gallium nitride layer are sequentially grown to form a non-porous gallium nitride thick film. The third low-temperature gallium nitride layer is a gallium nitride film grown in a low-temperature range, and the fourth high-temperature gallium nitride layer is a doped gallium nitride film grown in a high-temperature range.

[0008] Preferably, N is greater than or equal to 10 and less than or equal to 20. The porous and non-porous periodic structure of this scheme with 10-20 cycles results in a porous gallium nitride thick film with a relatively large thickness and structural stability.

[0009] Preferably, during the growth of the first epitaxial layer, in each cycle of growing the first low-temperature gallium nitride layer and the second high-temperature gallium nitride layer, the ratio of the time without silane to the time with silane is 1:3, and the silicon doping concentration in the first low-temperature gallium nitride layer is 1E19-3E19 cm⁻¹. -3 .

[0010] Preferably, the low temperature range for growing the first low-temperature gallium nitride layer is 850-950°C, and the high temperature range for growing the second high-temperature gallium nitride layer is 1000-1100°C.

[0011] Preferably, the thickness ratio of the second high-temperature gallium nitride layer to the first low-temperature gallium nitride layer is less than or equal to 1:15.

[0012] Preferably, the total thickness of the first low-temperature gallium nitride layer is 250-350 μm, and the total thickness of the second high-temperature gallium nitride layer is 10-20 μm.

[0013] Preferably, the gallium nitride template further includes a buffer layer grown on the growth substrate, the first epitaxial layer being grown on the side of the buffer layer away from the growth substrate, the buffer layer being a gallium nitride layer, and the thickness of the buffer layer being 3-5 μm.

[0014] Preferably, the gallium nitride template further includes a buffer layer grown on the growth substrate, the first epitaxial layer being grown on the side of the buffer layer away from the growth substrate, the buffer layer being a gallium nitride layer, and peeling the growth substrate off the buffer layer specifically includes: using an ultraviolet laser to scan the heated side of the gallium nitride template away from the first epitaxial layer to peel off the growth substrate.

[0015] Specifically, the heating temperature of the gallium nitride template scanned by the ultraviolet laser is 800-900 degrees Celsius.

[0016] Preferably, the fourth high-temperature gallium nitride layer is a silicon-doped gallium nitride layer, and the silicon doping concentration is 1E18-5E18 cm⁻¹. -3 .

[0017] Preferably, the fourth high-temperature gallium nitride layer is a carbon-doped gallium nitride layer, and the carbon doping concentration is 5E18-10E18 cm⁻¹. -3 .

[0018] Preferably, the thickness ratio of the third low-temperature gallium nitride layer to the fourth high-temperature gallium nitride layer is less than or equal to 1:30.

[0019] Specifically, the thickness of the third low-temperature gallium nitride layer is 5-10 μm, and the thickness of the fourth high-temperature gallium nitride layer is 250-350 μm.

[0020] Preferably, after growing the non-porous gallium nitride thick film, the process further includes: grinding and polishing the side of the porous gallium nitride thick film away from the non-porous gallium nitride thick film and / or grinding and polishing the side of the non-porous gallium nitride thick film away from the porous gallium nitride thick film, so as to thin the gallium nitride substrate to a predetermined thickness.

[0021] The present invention also provides a method for fabricating a semiconductor device, wherein a gallium nitride substrate is fabricated using the gallium nitride substrate fabrication method described above; a semiconductor epitaxial structure is grown on the side of the gallium nitride substrate away from the porous gallium nitride thick film; and the side of the gallium nitride substrate away from the semiconductor epitaxial structure is ground and polished to remove the porous gallium nitride thick film, thereby fabricating a semiconductor device.

[0022] Preferably, when grinding and polishing the gallium nitride substrate on the side away from the semiconductor epitaxial structure, the third low-temperature gallium nitride layer is also completely removed, so that the fourth high-temperature gallium nitride layer serves as the sole support substrate for the semiconductor device.

[0023] The present invention also provides a gallium nitride substrate, which is fabricated by the gallium nitride substrate fabrication method described above.

[0024] The present invention also provides a gallium nitride substrate, comprising a porous gallium nitride thick film and a non-porous gallium nitride thick film. The porous gallium nitride thick film is formed by N first low-temperature gallium nitride layers and second high-temperature gallium nitride layers stacked alternately from bottom to top. The first low-temperature gallium nitride layer is a silicon-doped gallium nitride layer and forms a porous structure in the region where silicon is concentrated. The non-porous gallium nitride thick film is grown on the uppermost second high-temperature gallium nitride layer of the porous gallium nitride thick film, and includes a third low-temperature gallium nitride layer and a fourth high-temperature gallium nitride layer from bottom to top. N is 1 or an integer greater than or equal to 2.

[0025] Preferably, the thickness ratio of the second high-temperature gallium nitride layer to the first low-temperature gallium nitride layer is less than or equal to 1:15, and the thickness ratio of the third low-temperature gallium nitride layer to the fourth high-temperature gallium nitride layer is less than or equal to 1:30.

[0026] Specifically, the total thickness of the low-temperature porous gallium nitride layer is 250-350 μm, the total thickness of the second high-temperature gallium nitride layer is 10-20 μm, the thickness of the third low-temperature gallium nitride layer is 5-10 μm, and the thickness of the fourth high-temperature gallium nitride layer is 250-350 μm.

[0027] Preferably, N is greater than or equal to 10 and less than or equal to 20.

[0028] Preferably, the silicon doping concentration in the first low-temperature gallium nitride layer is 1E19-3E19 cm⁻¹. -3 .

[0029] Preferably, the fourth high-temperature gallium nitride layer is a silicon-doped gallium nitride layer, and the silicon doping concentration is 1E18-5E18 cm⁻¹. -3 .

[0030] Preferably, the fourth high-temperature gallium nitride layer is a carbon-doped gallium nitride layer, and the carbon doping concentration is 5E18-10E18 cm⁻¹. -3 .

[0031] Compared with existing technologies, this invention can be used for the growth substrate structure and fabrication method of large-size gallium nitride homoepitaxial growth. This invention prepares a gallium nitride substrate structure with a first low-temperature gallium nitride layer on the back side through two epitaxial growth cycles and one electrochemical etching process. During epitaxial growth, the thermal expansion coefficient of this special composite structure gallium nitride substrate decreases due to the presence of holes on the back side, thus mitigating the problem of faster back-side expansion caused by the higher temperature of the back side compared to the front side. This reduces the negative warpage caused by the temperature difference between the upper and lower surfaces of the gallium nitride substrate. Furthermore, the flatness of the gallium nitride substrate improves the spatial uniformity of surface temperature during the epitaxial growth of large-size gallium nitride substrates, thereby increasing the temperature-dependent film thickness and the uniformity of film doping components (such as Al and In). In addition, this invention also forms a third low-temperature gallium nitride layer grown at a low temperature between the porous gallium nitride thick film and the fourth high-temperature gallium nitride layer requiring self-support. The lower temperature results in a higher oxygen content and an n-type bias, which allows for better lattice matching between the porous gallium nitride thick film and the fourth high-temperature gallium nitride layer, reducing dislocation density. On the other hand, when N is greater than or equal to 2, the porous gallium nitride thick film of the present invention is a porous / non-porous periodic structure, which can make the porous gallium nitride thick film achieve a relatively thick thickness, while not collapsing so that the gallium nitride lattice becomes a chaotic polycrystalline structure. Attached Figure Description

[0032] Figure 1 This is a flowchart of the first half of the method for fabricating a gallium nitride substrate according to the present invention.

[0033] Figure 2 This is a flowchart of the latter part of the method for fabricating a gallium nitride substrate according to the present invention.

[0034] Figure 3 This is a partial flowchart of the method for fabricating the semiconductor device of the present invention.

[0035] Figure 4 This is a structural diagram of a gallium nitride substrate in one embodiment of the present invention.

[0036] Figure 5 This is a structural diagram of a semiconductor device according to an embodiment of the present invention.

[0037] Figure 6 This is a structural diagram of a gallium nitride substrate in another embodiment of the present invention. Detailed Implementation

[0038] To illustrate the technical content, structural features, objectives, and effects of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0039] refer to Figure 1 and Figure 2 The present invention discloses a method for fabricating a gallium nitride substrate, comprising steps S1 to S6.

[0040] refer to Figure 1 Step S1, provide gallium nitride template 10.

[0041] The gallium nitride template 10 includes a growth substrate 11 and a buffer layer 12 grown on the growth substrate 11. In this embodiment, the buffer layer 12 is a gallium nitride layer, and the thickness of the buffer layer 12 is 4 μm. Preferably, the thickness of the buffer layer 12 is 3-5 μm. Of course, the thickness of the buffer layer 12 is not limited to the above values ​​and can be set according to actual needs.

[0042] Step S1, providing the gallium nitride template 10, specifically includes the step of growing a buffer layer 12 on the growth substrate 11. The growth substrate 11 can be a sapphire substrate or a growth substrate of other materials. The buffer layer 12 is an unintentionally doped gallium nitride layer (UGaN).

[0043] refer to Figure 1 In step S2, N first low-temperature gallium nitride layers 21 and N second high-temperature gallium nitride layers 22 are alternately grown sequentially on the gallium nitride template 10. The first low-temperature gallium nitride layer 21 is a silicon-doped gallium nitride film grown in a low-temperature range, and the second high-temperature gallium nitride layer 22 is an undoped gallium nitride film grown in a high-temperature range, to form a first epitaxial layer 20 formed by the alternating growth of N first low-temperature gallium nitride layers 21 and N second high-temperature gallium nitride layers 22, where N is an integer of 1 or greater than or equal to 2. The first epitaxial layer 20 is epitaxially grown using the HVPE method.

[0044] The first epitaxial layer 20 is grown on the side of the buffer layer 12 away from the growth substrate 11.

[0045] During the growth of the first epitaxial layer 20, a silicon-doped first low-temperature gallium nitride layer 21 is grown sequentially or repeatedly in a low-temperature range, and an undoped second high-temperature gallium nitride layer 22 is grown in a high-temperature range. (Reference) Figure 4 and Figure 6 In this embodiment, N is greater than or equal to 10 and less than or equal to 20. The first low-temperature gallium nitride layer 21 is grown in a low-temperature range of 850-950°C, and the second high-temperature gallium nitride layer 22 is grown in a high-temperature range of 1000-1100°C.

[0046] The thickness ratio of the first low-temperature gallium nitride layer 21 to the second high-temperature gallium nitride layer 22 is less than or equal to 1:15. Specifically, the total thickness of the first low-temperature gallium nitride layer 21 is 250-350 μm, and the total thickness of the second high-temperature gallium nitride layer 22 is 10-20 μm.

[0047] In this embodiment, during the growth of the first epitaxial layer 20, the ratio of the time without silane to the time with silane is 1:3. Silane is introduced during the growth of the first low-temperature gallium nitride layer 21, and not during the growth of the second high-temperature gallium nitride layer 22. Within one growth cycle, the ratio of the time without silane to the time with silane is 1:3. The silicon doping concentration in the first low-temperature gallium nitride layer 21 is 1E19-3E19 cm⁻¹. -3 .

[0048] refer to Figure 1 Step S3: Remove the growth substrate 11 of the gallium nitride template 10.

[0049] Step S3 specifically includes: using an ultraviolet laser to scan the side of the heated gallium nitride template away from the first epitaxial layer 20 to peel off the growth substrate 11.

[0050] The heating temperature of the gallium nitride template 10 scanned by ultraviolet laser is 800-900 degrees Celsius.

[0051] refer to Figure 1 In step S4, the first epitaxial layer 20 is etched by electrochemical etching. When the current flows through the silicon-doped low-temperature gallium nitride layer 21, the silicon impurities will accumulate and form etch holes. Each of the first low-temperature gallium nitride layers 21 is etched to form a hole structure and becomes a low-temperature porous gallium nitride layer 21a, so that the first epitaxial layer 20 is etched into a porous gallium nitride thick film 20a.

[0052] The purpose of low-temperature silicon doping of gallium nitride in the first low-temperature gallium nitride layer 21 is for electrochemical etching. When current flows through silicon doped gallium nitride, etching holes are formed. Etching holes often exist in places where silicon impurities are more concentrated.

[0053] Preferably, the etchant used in the electrochemical etching is oxalic acid, and the voltage applied across the first epitaxial layer 20 is 5-10V. The current and solution concentration for the electrochemical etching are performed according to commonly used electrochemical etching processes in existing technologies. By matching the appropriate voltage and Si impurity concentration, porous structures are formed in the silicon-doped layer of the first gallium nitride thick film, thus fabricating a porous gallium nitride thick film 20a.

[0054] refer to Figure 2 In step S5, a third low-temperature gallium nitride layer 31 and a fourth high-temperature gallium nitride layer 32 are sequentially grown on the side of the porous gallium nitride thick film 20a away from the buffer layer 12 to form a non-porous gallium nitride thick film 30 composed of the third low-temperature gallium nitride layer 31 and the fourth high-temperature gallium nitride layer 32. The third low-temperature gallium nitride layer 31 is a gallium nitride film grown in the low-temperature range, and the fourth high-temperature gallium nitride layer 32 is a doped gallium nitride film grown in the high-temperature range.

[0055] The porous gallium nitride thick film 30 is fabricated as a second epitaxial layer using HVPE. The thickness ratio of the third low-temperature gallium nitride layer 31 to the fourth high-temperature gallium nitride layer 32 is less than or equal to 1:30. Specifically, the thickness of the third low-temperature gallium nitride layer 31 is 5-10 μm, and the thickness of the fourth high-temperature gallium nitride layer 32 is 250-350 μm.

[0056] The third low-temperature gallium nitride layer 31 will be removed after the subsequent semiconductor device growth, therefore the third low-temperature gallium nitride layer 31 is an unintentionally doped gallium nitride layer. The third low-temperature gallium nitride layer 31 is used to reduce dislocation density under lattice mismatch. The third low-temperature gallium nitride layer 31 is grown at a low temperature, resulting in a high oxygen content and an n-type bias.

[0057] Specifically, the low-temperature range during the growth of the first epitaxial layer 20 is consistent with the low-temperature range during the growth of the second epitaxial layer, and the high-temperature range during the growth of the first epitaxial layer 20 is consistent with the high-temperature range during the growth of the second epitaxial layer. During the growth of the second epitaxial layer, the temperature can be a fixed value or can gradually vary within the corresponding high-temperature and low-temperature ranges.

[0058] In this embodiment, the porous gallium nitride thick film 30 is composed of a third low-temperature gallium nitride layer 31 and a fourth high-temperature gallium nitride layer 32. However, this is not the only embodiment. In another embodiment, the porous gallium nitride thick film 30 can be formed by alternating layers of third low-temperature gallium nitride layers 31 and fourth high-temperature gallium nitride layers 32. The bottommost layer of the second high-temperature gallium nitride layer 21 grown on the porous gallium nitride thick film 20a is the third low-temperature gallium nitride layer 31, and the topmost layer of the porous gallium nitride thick film 30 furthest from the porous gallium nitride thick film 20a is the fourth high-temperature gallium nitride layer 32, with a thickness of 250-350 μm.

[0059] When there are multiple layers of the third low-temperature gallium nitride layer 31 and the fourth high-temperature gallium nitride layer 32, the temperature during the growth of the multiple layers of the third low-temperature gallium nitride layer 31 increases linearly from bottom to top. The temperature during the growth of the multiple layers of the fourth high-temperature gallium nitride layer 32 also increases linearly from bottom to top, and the doping concentration of the fourth high-temperature gallium nitride layer 32 gradually increases.

[0060] In one embodiment, the fourth high-temperature gallium nitride layer 32 is silicon-doped, making the fabricated gallium nitride substrate 100 a silicon-doped n-type gallium nitride substrate, which can be used to grow blue-green laser epitaxy and fabricate blue-green laser devices. The silicon doping concentration is 1E18-5E18 cm⁻¹. -3 .

[0061] In another embodiment, the fourth high-temperature gallium nitride layer 32 is carbon-doped, and the fabricated gallium nitride substrate 100 is a carbon-doped high-resistivity gallium nitride layer, which can be used to grow power or radio frequency device epitaxy and fabricate power and radio frequency devices. The carbon doping concentration is 5E18-10E18 cm⁻¹. -3 .

[0062] refer to Figure 2 Following step S5, step S6 is further included, in which the gallium nitride substrate 100 is thinned to a predetermined thickness by grinding and polishing the side of the porous gallium nitride thick film 20a away from the non-porous gallium nitride thick film 30 and / or the side of the non-porous gallium nitride thick film 30 away from the porous gallium nitride thick film 20a. Grinding and polishing the side of the non-porous gallium nitride thick film 30 away from the porous gallium nitride thick film 20a can thin the fourth high-temperature gallium nitride layer 32 to a predetermined thickness.

[0063] Among them, grinding and polishing the non-porous gallium nitride thick film 30 to the side away from the porous gallium nitride thick film 20a can reduce the thickness of the fourth high-temperature gallium nitride layer 32. In this embodiment, the thickness of the fourth high-temperature gallium nitride layer 32 is reduced from 300um to 250um.

[0064] refer to Figure 3 The present invention also provides a method for manufacturing a semiconductor device, including steps S1 to S8.

[0065] Gallium nitride substrate 100 is fabricated through steps S1 to S6.

[0066] S7, a semiconductor epitaxial structure is grown on the side of the gallium nitride substrate 100 away from the porous gallium nitride thick film 20a.

[0067] S8, the side of the gallium nitride substrate 100 away from the semiconductor epitaxial structure is thinned by grinding and polishing to remove the porous gallium nitride thick film 20a, thereby fabricating a semiconductor device.

[0068] When thinning the side of the gallium nitride substrate 100 away from the semiconductor epitaxial structure, the third low-temperature gallium nitride layer 31 is removed by grinding and polishing, so that the fourth high-temperature gallium nitride layer 32 serves as the support substrate 11 of the semiconductor device.

[0069] The semiconductor device can be a blue-green laser device, a power device, or a radio frequency device.

[0070] refer to Figure 2 The present invention also discloses a gallium nitride substrate 100, which is manufactured by the gallium nitride substrate manufacturing method described above.

[0071] refer to Figure 5The gallium nitride substrate 100 includes a porous gallium nitride thick film 20a and a non-porous gallium nitride thick film 30. The porous gallium nitride thick film 20a is formed by N first low-temperature gallium nitride layers 21a and second high-temperature gallium nitride layers 22 stacked alternately from bottom to top. The first low-temperature gallium nitride layer 21a is a silicon-doped gallium nitride layer and forms a porous structure in the silicon-gathering region. The non-porous gallium nitride thick film 30 includes a third low-temperature gallium nitride layer 31 grown on the second high-temperature gallium nitride layer 22 and a fourth high-temperature gallium nitride layer 32 grown on the third low-temperature gallium nitride layer 31, where N is 1.

[0072] The thickness ratio of the second high-temperature gallium nitride layer 22 to the low-temperature porous gallium nitride layer 21a is less than or equal to 1:15, and the thickness ratio of the third low-temperature gallium nitride layer 31 to the fourth high-temperature gallium nitride layer 32 is less than or equal to 1:30.

[0073] Specifically, the total thickness of the low-temperature porous gallium nitride layer 22 is 250-350 μm, the total thickness of the second high-temperature gallium nitride layer 22 is 10-20 μm, the thickness of the third low-temperature gallium nitride layer 31 is 5-10 μm, and the thickness of the fourth high-temperature gallium nitride layer 32 is 250-350 μm.

[0074] In one embodiment, the fourth high-temperature gallium nitride layer 32 is silicon-doped, making the fabricated gallium nitride substrate 100 a silicon-doped n-type gallium nitride substrate, which can be used to grow blue-green laser epitaxy and fabricate blue-green laser devices. The silicon doping concentration is 1E18-5E18 cm⁻¹. -3 .

[0075] In another embodiment, the fourth high-temperature gallium nitride layer 32 is carbon-doped, and the fabricated gallium nitride substrate 100 is a carbon-doped high-resistivity gallium nitride layer, which can be used to grow power or radio frequency device epitaxy and fabricate power and radio frequency devices. The carbon doping concentration is 5E18-10E18 cm⁻¹. -3 .

[0076] refer to Figure 6 In another embodiment, N is an integer greater than or equal to 2. Specifically, N is greater than or equal to 10 and less than or equal to 20.

[0077] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method of fabricating a gallium nitride substrate, comprising: The method comprises the following steps: alternately growing N first low-temperature gallium nitride layers and N second high-temperature gallium nitride layers on a gallium nitride template from bottom to top to form a first epitaxial layer, the gallium nitride template comprising a growth substrate, the first low-temperature gallium nitride layer being a silicon-doped gallium nitride film grown in a low-temperature range, the second high-temperature gallium nitride layer being an undoped gallium nitride film grown in a high-temperature range, and N being an integer of 1 or greater than or equal to 2; stripping the growth substrate of the gallium nitride template; electrochemically etching the first epitaxial layer, and when current flows through the silicon-doped first low-temperature gallium nitride layer, a corrosion hole is formed at a place where silicon impurities are accumulated, so that each of the first low-temperature gallium nitride layers is etched into a hole structure, and the first epitaxial layer is etched into a porous gallium nitride thick film; growing a third low-temperature gallium nitride layer and a fourth high-temperature gallium nitride layer on the uppermost second high-temperature gallium nitride layer of the porous gallium nitride thick film to form a non-porous gallium nitride thick film, the third low-temperature gallium nitride layer being a gallium nitride film grown in a low-temperature range, and the fourth high-temperature gallium nitride layer being a doped gallium nitride film grown in a high-temperature range; the low-temperature range in which the first low-temperature gallium nitride layer and the third low-temperature gallium nitride layer are grown is 850-950 ℃, and the high-temperature range in which the second high-temperature gallium nitride layer and the fourth high-temperature gallium nitride layer are grown is 1000-1100 ℃.

2. The method of claim 1, wherein: N is equal to or greater than 10 and equal to or less than 20, and in growing the first epitaxial layer, a ratio of a time when silane is not supplied to a time when silane is supplied in each cycle of growing the first low-temperature gallium nitride layer and the second high-temperature gallium nitride layer is 1:3, and a doping concentration of silicon doping in the first low-temperature gallium nitride layer is 1E19 cm -3 -3E19 cm -3 .

3. The method of claim 1, wherein: The thickness ratio of the second high-temperature gallium nitride layer to the first low-temperature gallium nitride layer is less than or equal to 1:15, and the thickness ratio of the third low-temperature gallium nitride layer to the fourth high-temperature gallium nitride layer is less than or equal to 1:

30.

4. The method of claim 1, wherein: The total thickness of the first low-temperature gallium nitride layer is 250-350 um, the total thickness of the second high-temperature gallium nitride layer is 10-20 um, the thickness of the third low-temperature gallium nitride layer is 5-10 um, and the thickness of the fourth high-temperature gallium nitride layer is 250-350 um.

5. The method of claim 1, wherein: The gallium nitride template further comprises a buffer layer grown on the growth substrate, and the first epitaxial layer is grown on a side of the buffer layer away from the growth substrate, the buffer layer being a gallium nitride layer, and the thickness of the buffer layer being 3-5 um.

6. The method of claim 1, wherein: The gallium nitride template further comprises a buffer layer grown on the growth substrate, and the first epitaxial layer is grown on a side of the buffer layer away from the growth substrate, the buffer layer being a gallium nitride layer, and the stripping of the growth substrate from the buffer layer specifically comprises: scanning a heated gallium nitride template away from a side of the first epitaxial layer using ultraviolet laser to strip the growth substrate.

7. The method of claim 6, wherein: The heating temperature of the gallium nitride template in the ultraviolet laser scanning is 800-900 ℃.

8. The method of fabricating a gallium nitride substrate as claimed in claim 1, wherein: The fourth high-temperature gallium nitride layer is a silicon-doped gallium nitride layer, and the concentration of silicon doping is 1 E18 cm -3 -5E18cm -3 ; or, the fourth high-temperature gallium nitride layer is a carbon-doped gallium nitride layer, and the concentration of carbon doping is 5 E18 cm -3 -10E18cm -3 .

9. The method of claim 1, wherein: After the non-porous gallium nitride thick film is grown, the method further comprises: grinding and polishing a side of the porous gallium nitride thick film away from the non-porous gallium nitride thick film and / or a side of the non-porous gallium nitride thick film away from the porous gallium nitride thick film to thin the gallium nitride substrate to a preset thickness.

10. The method of fabricating a gallium nitride substrate as claimed in claim 1, wherein: When the first epitaxial layer is electrochemically etched, the voltage applied to both ends of the first epitaxial layer 20 is 5-10 V.

11. A method for manufacturing a semiconductor device, characterized by Fabricating a gallium nitride substrate using the method of claim 1-10; Growth of a semiconductor epitaxial structure on the side of the gallium nitride substrate away from the porous gallium nitride thick film; Grinding and polishing the side of the gallium nitride substrate away from the semiconductor epitaxial structure to remove the porous gallium nitride thick film to fabricate a semiconductor device.

12. The method of fabricating a semiconductor device of claim 11, wherein: When grinding and polishing the side of the gallium nitride substrate away from the semiconductor epitaxial structure, the third low-temperature gallium nitride layer is also completely removed, so that the fourth high-temperature gallium nitride layer is used alone as the supporting substrate of the semiconductor device.

13. A gallium nitride substrate, characterized by: The porous gallium nitride thick film is alternately stacked from bottom to top by N first low-temperature gallium nitride layers and second high-temperature gallium nitride layers, the first low-temperature gallium nitride layer is a silicon-doped gallium nitride layer and forms a pore structure in the silicon accumulation area, and the non-porous gallium nitride thick film is grown on the uppermost second high-temperature gallium nitride layer of the porous gallium nitride thick film and includes a third low-temperature gallium nitride layer and a fourth high-temperature gallium nitride layer from bottom to top, N is an integer of 1 or greater than or equal to 2, the low-temperature range for growing the first low-temperature gallium nitride layer and the third low-temperature gallium nitride layer is 850-950 ℃, and the high-temperature range for growing the second high-temperature gallium nitride layer and the fourth high-temperature gallium nitride layer is 1000-1100 ℃.

14. The gallium nitride substrate as claimed in claim 13, characterized in that: The thickness ratio of the second high-temperature gallium nitride layer to the first low-temperature gallium nitride layer is less than or equal to 1:15, and the thickness ratio of the third low-temperature gallium nitride layer to the fourth high-temperature gallium nitride layer is less than or equal to 1:

30.

15. The gallium nitride substrate as claimed in claim 13, characterized in that: The total thickness of the first low-temperature gallium nitride layer is 250-350 um, the total thickness of the second high-temperature gallium nitride layer is 10-20 um, the thickness of the third low-temperature gallium nitride layer is 5-10 um, and the thickness of the fourth high-temperature gallium nitride layer is 250-350 um.

16. The gallium nitride substrate as claimed in claim 13, characterized in that: N is equal to or greater than 10 and equal to or less than 20, and a doping concentration of silicon doping in the first low-temperature gallium nitride layer is 1E19 cm -3 -3E19 cm -3 .

17. The gallium nitride substrate as claimed in claim 14, characterized in that: The fourth high-temperature gallium nitride layer is a silicon-doped gallium nitride layer, and the concentration of silicon doping is 1 E18 cm -3 -5E18cm -3 ; or, the fourth high-temperature gallium nitride layer is a carbon-doped gallium nitride layer, and the concentration of carbon doping is 5 E18 cm -3 -10E18cm -3 .

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