Gallium nitride substrate, manufacturing method thereof and manufacturing method of semiconductor device

Abstract

The invention discloses a manufacturing method of a gallium nitride substrate, which comprises the following steps: sequentially and 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 layers are silicon-doped gallium nitride films growing in a low-temperature range, and the second high-temperature gallium nitride layers are silicon-doped gallium nitride films growing in a low-temperature range; the second high-temperature gallium nitride layer is a non-doped gallium nitride film growing in a high-temperature range; stripping the growth substrate of the gallium nitride template; the first epitaxial layer is electrochemically etched, and each first low-temperature gallium nitride layer is etched to form a hole structure, so that the first epitaxial layer is etched to form a porous gallium nitride thick film; and sequentially 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 the non-porous gallium nitride thick film. According to the homogeneous gallium nitride substrate provided by the invention, the negative warping caused by the temperature difference between the upper surface and the lower surface of the growth substrate is reduced. The invention further discloses a manufacturing method of the semiconductor device and the gallium nitride substrate.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor growth substrate materials, and in particular to a structure and a preparation method of a gallium nitride substrate. Background Art

[0002] Although GaN single crystal growth substrates have disadvantages in price and size, the defect density of GaN layers epitaxially grown on homogeneous growth substrates is much lower than that of GaN layers epitaxially grown on heterogeneous substrates (Si, SiC). For example, the dislocation density of heterogeneous epitaxial GaN on Si growth substrate is generally 1E9cm －2 The dislocation density of epitaxial GaN on GaN free-standing substrates is usually reduced to 1E6 cm －2 Therefore, whether it is a laser chip or a power or radio frequency device, GaN single crystal growth substrate will be the best or even the only choice for high-performance, high-stability high-end products.

[0003] On the one hand, most commercial GaN self-supporting substrates are obtained by grinding and polishing after HVPE epitaxial growth. Due to technical and cost limitations, the thickness of GaN growth substrates is not large, generally around 500μm; on the other hand, the chip manufacturing process of RF devices and power devices is often carried out at a "large" size of 4-8 inches. However, during the epitaxial growth of gallium nitride substrates on large-size thin growth substrates, due to temperature differences, the growth substrate will form a very large negative warp, which will affect the thickness and component ratio of the epitaxial film layer, and thus affect the consistency of device performance, which is often unacceptable in the industrialization process of devices.

[0004] Therefore, there is an urgent need for a method and structure for manufacturing a gallium nitride substrate that can solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a method for manufacturing a gallium nitride substrate, to provide a homogenous gallium nitride substrate, and to reduce the negative warpage caused by the temperature difference between the upper and lower surfaces of the growth substrate.

[0006] In order to achieve the above-mentioned object, the present invention provides 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 from bottom to top on a gallium nitride template to form a first epitaxial layer, the gallium nitride template comprising a growth substrate, the first low-temperature gallium nitride layer is a silicon-doped gallium nitride film grown in a low-temperature range, the second high-temperature gallium nitride layer is a non-doped gallium nitride film grown in a high-temperature range, and N is 1 or an integer greater than or equal to 2; stripping the growth substrate of the gallium nitride template; electrochemical etching The first epitaxial layer, when current flows through the silicon-doped first low-temperature gallium nitride layer, corrosion holes are formed where silicon impurities gather, so that each of the first low-temperature gallium nitride layers is etched with a hole structure, and the first epitaxial layer is etched into a porous gallium nitride thick film; a third low-temperature gallium nitride layer and a fourth high-temperature gallium nitride layer are sequentially grown on the second high-temperature gallium nitride layer, which is the uppermost layer in the porous gallium nitride thick film, 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.

[0007] Preferably, N is greater than or equal to 10 and less than or equal to 20. The porous non-porous periodic structure of 10-20 periods in this solution enables the manufactured porous gallium nitride thick film to have a thicker thickness and a stable structure.

[0008] Preferably, when growing 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 doping concentration of silicon doping in the first low-temperature gallium nitride layer is 1E19-3E19cm －3 .

[0009] 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.

[0010] Preferably, a 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.

[0011] Preferably, the total thickness of the first low-temperature gallium nitride layer is 250-350 um, and the total thickness of the second high-temperature gallium nitride layer is 10-20 um.

[0012] Preferably, the gallium nitride template further comprises a buffer layer grown on the growth substrate, the first epitaxial layer is grown on a side of the buffer layer away from the growth substrate, the buffer layer is a gallium nitride layer, and the thickness of the buffer layer is 3-5 um.

[0013] Preferably, the gallium nitride template also includes a buffer layer grown on the growth substrate, the first epitaxial layer is grown on a side of the buffer layer away from the growth substrate, the buffer layer is a gallium nitride layer, and peeling the growth substrate from the buffer layer specifically includes: using an ultraviolet laser to scan a side of the heated gallium nitride template away from the first epitaxial layer to peel off the growth substrate.

[0014] Specifically, the heating temperature of the gallium nitride template scanned by the ultraviolet laser is 800 degrees Celsius to 900 degrees Celsius.

[0015] Preferably, the fourth high temperature gallium nitride layer is a silicon-doped gallium nitride layer, and the concentration of silicon doping is 1E18-5E18cm -3 .

[0016] Preferably, the fourth high temperature gallium nitride layer is a carbon-doped gallium nitride layer, and the carbon doping concentration is 5E18-10E18cm -3 .

[0017] Preferably, a 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.

[0018] Specifically, 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.

[0019] Preferably, after growing the second epitaxial layer, the method further includes: grinding and polishing a side of the porous gallium nitride thick film away from the non-porous gallium nitride thick film and / or grinding and polishing a 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 preset thickness.

[0020] The present invention also provides a method for manufacturing a semiconductor device, which comprises manufacturing a gallium nitride substrate using the method for manufacturing a gallium nitride substrate as described above; growing a semiconductor epitaxial structure on a side of the gallium nitride substrate away from the porous gallium nitride thick film; and grinding and polishing the side of the gallium nitride substrate away from the semiconductor epitaxial structure to remove the porous gallium nitride thick film, thereby manufacturing a semiconductor device.

[0021] Preferably, 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 alone serves as a supporting substrate for the semiconductor device.

[0022] The present invention also provides a gallium nitride substrate, which is manufactured by the above-mentioned method for manufacturing the gallium nitride substrate.

[0023] The present invention also provides a gallium nitride substrate, comprising a porous gallium nitride thick film and a non-porous gallium nitride thick film, wherein the porous gallium nitride thick film is formed by alternatingly stacking N first low-temperature porous gallium nitride layers and second high-temperature gallium nitride layers from bottom to top, wherein the first low-temperature porous gallium nitride layer is a silicon-doped gallium nitride layer and forms a hole structure in the silicon-aggregated area, and the non-porous gallium nitride thick film is grown on the second high-temperature gallium nitride layer which is the topmost layer of the porous gallium nitride thick film, and comprises a third low-temperature gallium nitride layer and a fourth high-temperature gallium nitride layer from bottom to top, wherein N is 1 or an integer greater than or equal to 2.

[0024] 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.

[0025] Specifically, the total thickness of the low-temperature porous gallium nitride layer is 250-350um, the total thickness of the second high-temperature gallium nitride layer is 10-20um, the thickness of the third low-temperature gallium nitride layer is 5-10um, and the thickness of the fourth high-temperature gallium nitride layer is 250-350um.

[0026] Preferably, N is greater than or equal to 10 and less than or equal to 20.

[0027] Preferably, the doping concentration of silicon doping in the first low-temperature gallium nitride layer is 1E19-3E19cm －3 .

[0028] Preferably, the fourth high temperature gallium nitride layer is a silicon-doped gallium nitride layer, and the concentration of silicon doping is 1E18-5E18cm -3 .

[0029] Preferably, the fourth high temperature gallium nitride layer is a carbon-doped gallium nitride layer, and the carbon doping concentration is 5E18-10E18cm -3 .

[0030] Compared with the prior art, the present invention can be used for the growth substrate structure of large-size gallium nitride homoepitaxial growth and its manufacturing method. The present invention prepares a gallium nitride substrate structure having a first low-temperature porous gallium nitride layer on the back side by two epitaxy and one electrochemical etching. When the gallium nitride substrate of this special composite structure is epitaxially grown, the thermal expansion coefficient will decrease due to the presence of holes on the back, so the problem of faster expansion of the back side caused by the back temperature of the gallium nitride substrate being higher than the front temperature can be alleviated, thereby reducing the negative warping caused by the temperature difference between the upper and lower surfaces of the gallium nitride substrate. The flatness of the gallium nitride substrate will improve the spatial uniformity of the surface temperature during the epitaxial growth of the large-size gallium nitride substrate, thereby improving the thickness of the film layer affected by temperature, and the uniformity of the doping components (such as Al, In) of the film layer. On the other hand, the present invention also forms a third low-temperature gallium nitride layer grown at low temperature between the porous gallium nitride thick film and the fourth high-temperature gallium nitride layer that needs to be self-supported. The oxygen content will be high when the temperature is low, and it is n-type itself, which can make the porous gallium nitride thick film and the fourth high-temperature gallium nitride layer have better lattice adaptation and reduce the 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 has a porous / non-porous periodic structure, which can enable the porous gallium nitride thick film to achieve a thicker thickness while not collapsing to turn the gallium nitride lattice into a chaotic polycrystalline structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of the first half of the method for manufacturing a gallium nitride substrate of the present invention.

[0032] Figure 2 It is a flow chart of the second half of the method for manufacturing a gallium nitride substrate of the present invention.

[0033] Figure 3 It is a partial flow chart of the method for manufacturing a semiconductor device of the present invention.

[0034] Figure 4 is a structural diagram of a gallium nitride substrate in one embodiment of the present invention.

[0035] Figure 5 is a structural diagram of a semiconductor device in one embodiment of the present invention.

[0036] Figure 6 is a structural diagram of a gallium nitride substrate in another embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to explain the technical content, structural features, achieved objectives and effects of the present invention in detail, the following is a detailed description in conjunction with the implementation methods and the accompanying drawings.

[0038] refer to Figure 1 and Figure 2 The present invention discloses a method for manufacturing a gallium nitride substrate, comprising steps S1 to S6.

[0039] refer to Figure 1 , step S1, providing a gallium nitride template 10.

[0040] 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 um. Preferably, the thickness of the buffer layer 12 is 3-5 um. Of course, the thickness of the buffer layer 12 is not limited to the above values, and can be set according to actual needs.

[0041] Providing the gallium nitride template 10 in step S1 specifically includes: a step of growing a buffer layer 12 on the growth substrate 11. The growth substrate 11 may be a sapphire substrate or a growth substrate of other materials. The buffer layer 12 is an unintentionally doped gallium nitride layer (UGaN).

[0042] refer to Figure 1 , step S2, alternately growing N first low-temperature gallium nitride layers 21 and N second high-temperature gallium nitride layers 22 on the gallium nitride template 10, wherein 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 a non-doped gallium nitride film grown in a high-temperature range, so as to form a first epitaxial layer 20 formed by alternately growing the N first low-temperature gallium nitride layers 21 and the N second high-temperature gallium nitride layers 22, wherein N is 1 or an integer greater than or equal to 2. The first epitaxial layer 20 is epitaxially grown by HVPE.

[0043] The first epitaxial layer 20 is grown on a side of the buffer layer 12 away from the growth substrate 11 .

[0044] When growing the first epitaxial layer 20, a silicon-doped first low-temperature gallium nitride layer 21 is grown in a low-temperature range, and a non-doped second high-temperature gallium nitride layer 22 is grown in a high-temperature range in sequence or in multiple cycles. Figure 4 and Figure 6 In this embodiment, N is greater than or equal to 10 and less than or equal to 20. The low temperature range for growing the first low temperature gallium nitride layer 21 is 850-950°C, and the high temperature range for growing the second high temperature gallium nitride layer 22 is 1000-1100°C.

[0045] 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 um, and the total thickness of the second high temperature gallium nitride layer 22 is 10-20 um.

[0046] In this embodiment, when growing the first epitaxial layer 20, the ratio of the time without silane to the time with silane is 1:3. When growing the first low-temperature gallium nitride layer 21, silane is passed, and when growing the second high-temperature gallium nitride layer 22, silane is not passed. In one growth cycle, the ratio of the time without silane to the time with silane is 1:3. The doping concentration of silicon doping in the first low-temperature gallium nitride layer 21 is 1E19-3E19cm －3 .

[0047] refer to Figure 1 , step S3, peeling off the growth substrate 11 of the gallium nitride template 10.

[0048] Step S3 specifically includes: using an ultraviolet laser to scan the heated gallium nitride template on a side away from the first epitaxial layer 20 to peel off the growth substrate 11 .

[0049] Wherein, the heating temperature of the gallium nitride template 10 scanned by the ultraviolet laser is 800-900 degrees Celsius.

[0050] refer to Figure 1 In step S4, the first epitaxial layer 20 is electrochemically etched. When current flows through the silicon-doped low-temperature gallium nitride layer 21, corrosion holes are formed where silicon impurities gather. Each of the first low-temperature gallium nitride layers 21 is etched with a hole structure to become 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.

[0051] The purpose of low-temperature silicon-doped gallium nitride in the first low-temperature gallium nitride layer 21 is to use it for electrochemical corrosion. When current flows through silicon-doped gallium nitride, corrosion holes will be formed. Etching holes often exist where silicon impurities are concentrated.

[0052] Preferably, the electrochemical etching solution is oxalic acid, the voltage applied to both ends of the first epitaxial layer 20 is 5-10V, and the current and solution concentration of the electrochemical etching are carried out according to the electrochemical etching process commonly used in the prior art. By matching the appropriate voltage and Si impurity concentration, the silicon doped layer in the first gallium nitride thick film is porous, and a porous gallium nitride thick film 20a is prepared.

[0053] refer to Figure 2 , step S5, sequentially growing a third low-temperature gallium nitride layer 31 and a fourth high-temperature gallium nitride layer 32 on a 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 consisting of the third low-temperature gallium nitride layer 31 and the fourth high-temperature gallium nitride layer 32, wherein the third low-temperature gallium nitride layer 31 is a gallium nitride film grown in a low-temperature range, and the fourth high-temperature gallium nitride layer 32 is a doped gallium nitride film grown in a high-temperature range.

[0054] The preparation of the non-porous gallium nitride thick film 30 is a second epitaxial layer made 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 5-10um, and the thickness of the fourth high-temperature gallium nitride layer 32 is 250-350um.

[0055] The third low-temperature gallium nitride layer 31 will be ground off after the subsequent semiconductor device growth, so 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 the dislocation density under lattice mismatch. The third low-temperature gallium nitride layer 31 grows at a low temperature, has a high oxygen content, and is n-type.

[0056] The low temperature range when growing the first epitaxial layer 20 is consistent with the low temperature range when growing the second epitaxial layer, and the high temperature range when growing the first epitaxial layer 20 is consistent with the high temperature range when growing the second epitaxial layer. When the second epitaxial layer is grown, the temperature can be a fixed temperature value or can be gradually changed within the corresponding high temperature range and low temperature range.

[0057] In this embodiment, the non-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. Of course, not limited to this, in another embodiment, the non-porous gallium nitride thick film 30 can be formed by alternating multiple third low-temperature gallium nitride layers 31 and multiple fourth high-temperature gallium nitride layers 32 in sequence, and the bottom layer of the second high-temperature gallium nitride layer 21 grown on the porous gallium nitride thick film 20a in the non-porous gallium nitride thick film 30 is the third low-temperature gallium nitride layer 31, and the top layer of the non-porous gallium nitride thick film 30 away from the porous gallium nitride thick film 20a is the fourth high-temperature gallium nitride layer 32, and the thickness of the fourth high-temperature gallium nitride layer 32 is 250-350um.

[0058] 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 of the multiple layers of the third low-temperature gallium nitride layer 31 increases linearly from bottom to top during growth. The temperature of the multiple layers of the fourth high-temperature gallium nitride layer 32 increases linearly from bottom to top during growth, and the doping concentration of the fourth high-temperature gallium nitride layer 32 increases gradually.

[0059] In one embodiment, the fourth high temperature gallium nitride layer 32 is doped with silicon, so that the manufactured gallium nitride substrate 100 is a silicon-doped n-type gallium nitride substrate, which can be used to grow blue-green laser epitaxy and manufacture blue-green laser devices. The concentration of silicon doping is 1E18-5E18cm -3 .

[0060] In another embodiment, the fourth high temperature gallium nitride layer 32 is carbon doped, and the manufactured gallium nitride substrate 100 is a carbon doped high resistance gallium nitride layer, which can be used to grow power or radio frequency device epitaxy and manufacture power and radio frequency devices. The carbon doping concentration is 5E18-10E18cm -3 .

[0061] refer to Figure 2 , after step S5, the method further includes step S6, wherein 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 are ground and polished to thin the gallium nitride substrate 100 to a preset thickness. The fourth high-temperature gallium nitride layer 32 can be thinned to a preset thickness by grinding and polishing the side of the non-porous gallium nitride thick film 30 away from the porous gallium nitride thick film 20a.

[0062] By grinding and polishing the side of the non-porous gallium nitride thick film 30 away from the porous gallium nitride thick film 20a, the thickness of the fourth high-temperature gallium nitride layer 32 can be reduced. In this embodiment, the thickness of the fourth high-temperature gallium nitride layer 32 is reduced from 300um to 250um.

[0063] refer to Figure 3 The present invention also provides a method for manufacturing a semiconductor device, including steps S1 to S8.

[0064] The gallium nitride substrate 100 is manufactured through steps S1 to S6.

[0065] S7 , growing a semiconductor epitaxial structure on a side of the gallium nitride substrate 100 away from the porous gallium nitride thick film 20 a .

[0066] S8, thinning the side of the gallium nitride substrate 100 away from the semiconductor epitaxial structure by grinding and polishing to remove the porous gallium nitride thick film 20a, thereby manufacturing a semiconductor device.

[0067] When the side of the gallium nitride substrate 100 away from the semiconductor epitaxial structure is thinned, 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 supporting substrate 11 of the semiconductor device.

[0068] Among them, the semiconductor device can be a blue-green laser device, a power and radio frequency device, etc.

[0069] refer to Figure 2 The present invention also discloses a gallium nitride substrate 100, which is manufactured by the above-mentioned method for manufacturing the gallium nitride substrate.

[0070] 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 alternating N first low-temperature porous gallium nitride layers and second high-temperature gallium nitride layers 22 from bottom to top. The first low-temperature porous gallium nitride layer 20a is a silicon-doped gallium nitride layer and forms a hole structure in the silicon-aggregated area. 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. N is 1.

[0071] The thickness ratio of the second high temperature gallium nitride layer 22 to the low temperature porous gallium nitride layer 21 a 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.

[0072] Specifically, the total thickness of the low-temperature porous gallium nitride layer 22 is 250-350um, the total thickness of the second high-temperature gallium nitride layer 22 is 10-20um, the thickness of the third low-temperature gallium nitride layer 31 is 5-10um, and the thickness of the fourth high-temperature gallium nitride layer 32 is 250-350um.

[0073] In one embodiment, the fourth high temperature gallium nitride layer 32 is doped with silicon, so that the manufactured gallium nitride substrate 100 is a silicon-doped n-type gallium nitride substrate, which can be used to grow blue-green laser epitaxy and manufacture blue-green laser devices. The concentration of silicon doping is 1E18-5E18cm -3 .

[0074] In another embodiment, the fourth high temperature gallium nitride layer 32 is carbon doped, and the manufactured gallium nitride substrate 100 is a carbon doped high resistance gallium nitride layer, which can be used to grow power or radio frequency device epitaxy and manufacture power and radio frequency devices. The carbon doping concentration is 5E18-10E18cm -3 .

[0075] 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.

[0076] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention are still within the scope covered by the present invention.

Claims

1. A method for manufacturing a gallium nitride substrate, characterized in that: include: Alternatingly growing N first low-temperature gallium nitride layers and N second high-temperature gallium nitride layers from bottom to top on a gallium nitride template 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 a non-doped gallium nitride film grown in a high-temperature range, and N being 1 or an integer greater than or equal to 2; peeling off the growth substrate of the gallium nitride template; Electrochemically etching the first epitaxial layer, when current flows through the silicon-doped first low-temperature gallium nitride layer, corrosion holes are formed where silicon impurities are gathered, so that each of the first low-temperature gallium nitride layers is etched with a hole structure, and the first epitaxial layer is etched into a porous gallium nitride thick film; A third low-temperature gallium nitride layer and a fourth high-temperature gallium nitride layer are sequentially grown on the second high-temperature gallium nitride layer, which is the uppermost layer in the porous gallium nitride thick film, to form a non-porous gallium nitride thick film, wherein 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.

2. The method for manufacturing a gallium nitride substrate according to claim 1, wherein: N is greater than or equal to 10 and less than or equal to 20. When growing 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. The doping concentration of silicon doping in the first low-temperature gallium nitride layer is 1E19 cm －3 -3E19cm －3 .

3. The method for manufacturing a gallium nitride substrate according to claim 1, wherein: 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.

4. The method for manufacturing a gallium nitride substrate according to 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; 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.

5. The method for manufacturing a gallium nitride substrate according to claim 1, wherein: The total thickness of the first low-temperature gallium nitride layer is 250um-350um, and the total thickness of the second high-temperature gallium nitride layer is 10-20um; 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 um-350 um.

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

7. The method for manufacturing a gallium nitride substrate according to claim 1, wherein: The gallium nitride template also includes a buffer layer grown on the growth substrate, the first epitaxial layer is grown on a side of the buffer layer away from the growth substrate, the buffer layer is a gallium nitride layer, and peeling the growth substrate from the buffer layer specifically includes: using an ultraviolet laser to scan a side of the heated gallium nitride template away from the first epitaxial layer to peel off the growth substrate.

8. The method for manufacturing a gallium nitride substrate according to claim 7, wherein: The heating temperature of the gallium nitride template scanned by the ultraviolet laser is 800 degrees Celsius to 900 degrees Celsius.

9. The method for manufacturing a gallium nitride substrate according to claim 1, wherein: The fourth high temperature gallium nitride layer is a silicon-doped gallium nitride layer, and the concentration of silicon doping is 1E18cm -3 -5E18cm -3 Alternatively, the fourth high temperature gallium nitride layer is a carbon-doped gallium nitride layer, and the carbon doping concentration is 5E18cm -3 -10E18cm -3 .

10. The method for manufacturing a gallium nitride substrate according to claim 1, wherein: After growing the second epitaxial layer, the method further includes grinding and polishing a side of the porous gallium nitride thick film away from the non-porous gallium nitride thick film and / or grinding and polishing a 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 preset thickness.

11. The method for manufacturing a gallium nitride substrate according to claim 1, wherein: When the first epitaxial layer is electrochemically etched, the voltage applied to both ends of the first epitaxial layer 20 is 5-10V.

12. A method for manufacturing a semiconductor device, characterized in that: Manufacturing a gallium nitride substrate using the method for manufacturing a gallium nitride substrate according to any one of claims 1 to 11; growing a semiconductor epitaxial structure on a side of the gallium nitride substrate away from the porous gallium nitride thick film; 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 manufacturing a semiconductor device.

13. The method for manufacturing a semiconductor device according to claim 12, 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 alone serves as a supporting substrate for the semiconductor device.

14. A gallium nitride substrate, characterized in that: The invention comprises a porous gallium nitride thick film and a non-porous gallium nitride thick film, wherein the porous gallium nitride thick film is formed by alternatingly stacking N first low-temperature porous gallium nitride layers and second high-temperature gallium nitride layers from bottom to top, wherein the first low-temperature porous gallium nitride layer is a silicon-doped gallium nitride layer and forms a hole structure in the silicon-aggregated area, and the non-porous gallium nitride thick film is grown on the second high-temperature gallium nitride layer which is the uppermost layer of the porous gallium nitride thick film, and comprises a third low-temperature gallium nitride layer and a fourth high-temperature gallium nitride layer from bottom to top, wherein N is 1 or an integer greater than or equal to 2.

15. The gallium nitride substrate according to claim 14, 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.

16. The gallium nitride substrate according to claim 14, wherein: The total thickness of the low-temperature porous gallium nitride layer is 250um-350um, the total thickness of the second high-temperature gallium nitride layer is 10-20um, the thickness of the third low-temperature gallium nitride layer is 5-10um, and the thickness of the fourth high-temperature gallium nitride layer is 250um-350um.

17. The gallium nitride substrate according to claim 14, wherein: N is greater than or equal to 10 and less than or equal to 20, and the doping concentration of silicon doping in the first low-temperature gallium nitride layer is 1E19 cm －3 -3E19cm －3 .

18. The gallium nitride substrate according to claim 15, wherein: The fourth high temperature gallium nitride layer is a silicon-doped gallium nitride layer, and the concentration of silicon doping is 1E18cm -3 -5E18cm -3 Alternatively, the fourth high temperature gallium nitride layer is a carbon-doped gallium nitride layer, and the carbon doping concentration is 5E18cm -3 -10E18cm -3 .

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