CN116072517A - Method for recycling sapphire substrate - Google Patents
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- CN116072517A CN116072517A CN202211685648.8A CN202211685648A CN116072517A CN 116072517 A CN116072517 A CN 116072517A CN 202211685648 A CN202211685648 A CN 202211685648A CN 116072517 A CN116072517 A CN 116072517A
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- H—ELECTRICITY
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02002—Preparing wafers
- H01L21/02005—Preparing bulk and homogeneous wafers
- H01L21/02032—Preparing bulk and homogeneous wafers by reclaiming or re-processing
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- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02002—Preparing wafers
- H01L21/02005—Preparing bulk and homogeneous wafers
- H01L21/02008—Multistep processes
- H01L21/0201—Specific process step
- H01L21/02019—Chemical etching
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Abstract
The invention provides a method for recycling a sapphire substrate, which specifically comprises the following steps: and (3) placing the sapphire substrate with the epitaxial layer on the surface in a 50-60 wt% phosphoric acid solution, and heating at 180-350 ℃. The method obviously enhances the corrosion strength and speed of phosphoric acid, and can effectively remove the epitaxial layer on the surface of the sapphire substrate.
Description
Technical Field
The invention belongs to the technical field of photoelectricity. And more particularly, to a method of recycling a sapphire substrate.
Background
Compared with the first two-generation semiconductor material, the third-generation semiconductor material (such as gallium nitride, aluminum nitride and the like) has wider forbidden band width, higher breakdown electric field, higher thermal conductivity, higher electron saturation rate and higher radiation resistance, is more suitable for manufacturing high-temperature, high-frequency, radiation-resistant and high-power devices, is also commonly called a wide forbidden band semiconductor material (the forbidden band width is more than 2.2 eV), is also called a high-temperature semiconductor material, and commercial substrates for epitaxial growth mainly comprise silicon, sapphire, silicon carbide and the like. The silicon substrate has the advantages of low price, good thermal conductivity and the like, but has lower mechanical strength, is fragile, has larger lattice mismatch and thermal mismatch with gallium nitride, and is easy to crack in the growth process; silicon carbide substrates, although more lattice-constant matched to gallium nitride, are expensive, resulting in limited range of use; the sapphire substrate is widely used in the epitaxial growth of the third-generation semiconductor material due to smaller lattice mismatch and lower price, and is more suitable for being applied in the high-temperature growth process due to mature production technology, better device quality, higher mechanical strength and stronger stability.
In the epitaxial growth process of the third-generation semiconductor material, defective products with unqualified quality are inevitably existed, the production cost of the partially scrapped products is greatly increased, unnecessary waste is generated, and if the substrate can be recycled, the epitaxial layer on the surface can be cleaned, so that a clean and nondestructive substrate can be obtained, the reutilization can be realized, and the cost is reduced.
The existing sapphire substrate recovery methods have certain defects, for example, the prior art provides a method for recovering the sapphire substrate, and the method is complicated in process by adopting physical high-temperature baking and also needs to be matched with wet etching; in addition, as the prior art provides a method for recycling the sapphire substrate, a method of multiple times of liquid medicine etching and high-temperature baking is adopted to remove the gallium nitride related epitaxial material, but the method needs to be baked by introducing hydrogen under the high-temperature condition, so that the safety coefficient is lower; and then, etching the patterned sapphire substrate after the epitaxial layer is removed by adopting wet etching, but the method can only be used for recycling the patterned substrate and has an unsatisfactory recycling effect on the flat substrate.
Therefore, there is a need to find a method for efficiently recycling a flat sapphire substrate, which has a simple process and high safety factor, and has a considerable necessity for substrate resource utilization.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a method for recycling the sapphire substrate, which has simple process and high safety coefficient, so as to remove the epitaxial layer on the surface of the sapphire substrate, obtain the clean and nondestructive sapphire substrate, improve the recycling rate of the sapphire substrate, reduce the production cost of the sapphire substrate and epitaxial growth, and be applicable to patterned substrates and flat substrates at the same time, thereby having quite necessity for substrate resource utilization.
The above object of the present invention is achieved by the following technical scheme:
the invention provides a method for recycling a sapphire substrate, which specifically comprises the following steps: and (3) placing the sapphire substrate with the epitaxial layer on the surface in a 50-60 wt% phosphoric acid solution, and heating at 180-350 ℃.
The temperature of 180-350 ℃ is specifically selected, on one hand, because phosphoric acid can be further dehydrated to generate triphosphoric acid and metaphosphoric acid at high temperature (such as 180-350 ℃) and has stronger oxidizing property and corrosiveness; on the other hand, the oxidizing property of the phosphoric acid can be obviously enhanced at a higher temperature, so that the surface of the sapphire substrate can be modified, the surface of the sapphire substrate is changed from hydrophobicity to hydrophilicity, and the residual reactant on the surface of the sapphire substrate is easier to remove in a subsequent soaking and washing link. The invention only needs to use phosphoric acid as a chemical, so that the waste liquid treated by the method is easy to recycle, and the whole method has low cost and simple operation.
Preferably, the heating time is 5 to 8 hours.
Preferably, the preparation of the 50-60 wt% phosphoric acid solution comprises the following steps: placing phosphoric acid in an environment with humidity of 50-100% to naturally absorb water until the concentration is 50-60 wt%.
According to the method, concentrated phosphoric acid is utilized to absorb water from the water and corrode, the concentrated phosphoric acid is exposed to an environment with the humidity of 50% -100% (such as air with the humidity of 50% -100%), the concentrated phosphoric acid is stood for a period of time, when the phosphoric acid naturally absorbs water to the concentration of 50% -60% by weight, the sapphire substrate is placed in the phosphoric acid after water absorption to heat, the boiling point of the water is reached due to the fact that the temperature (180-350 ℃) is reached, the absorbed water of the phosphoric acid can be boiled, phosphoric acid is further caused to turn over, phosphoric acid consumed by the surface of the substrate can be supplemented in real time by the turned phosphoric acid, dense bubbles are generated, reaction products are taken away, corrosion strength and speed of the phosphoric acid are remarkably improved, and an epitaxial layer on the surface of the sapphire substrate can be effectively removed. In addition, after corrosion is finished, the acid liquor losing water can be recovered through standing, is recycled, does not need human intervention, and can be repeatedly used for recovering the sapphire substrate.
If 85wt% phosphoric acid solution is adopted, phosphoric acid cannot be turned over or bubble during the heating process, the corrosion process cannot be accelerated, and bubbling can only be realized through artificial ventilation, but the artificial ventilation can complicate the process and increase the process cost on one hand, and on the other hand, the ventilation mode can only ensure bubbling at a plurality of points, so that uniform bubbling cannot be realized as in the method of the invention, and the good effect of removing the epitaxial layer on the surface of the sapphire substrate cannot be realized.
If the 50-60 wt% phosphoric acid solution is prepared by directly adding water, the concentrated phosphoric acid is viscous liquid and cannot be naturally dissolved with water, so that the phenomenon that the upper layer is water and the lower layer is phosphoric acid occurs in the system, and a stirring process is required to ensure uniform mixing, so that the working procedures are increased. The natural water absorption mode can be used for matching the water absorption time according to the ambient humidity, so that the effect of uniform mixing is achieved, and the operation is simpler.
Most preferably, the preparation of the 50wt% phosphoric acid solution: placing phosphoric acid in an environment with the humidity of 80-100% (such as air with the humidity of 50-100%) to naturally absorb water until the concentration is 50wt%.
Preferably, the epitaxial layer is a gallium nitride based III-V compound.
Further preferably, the gallium nitride-based III-V compound is one or more of GaN, inGaN, alGaN.
Further preferably, the thickness of the epitaxial layer is less than 8 μm.
Preferably, after the heating, the sapphire substrate is further soaked.
Further preferably, the soaking time is 1 to 2 minutes.
Further preferably, the soaking is soaking with water.
More preferably, nitrogen is also introduced into the water during the soaking, so that the water is turned over.
The nitrogen is introduced in the soaking process, so that water is enabled to tumble, the sapphire substrate is modified by phosphoric acid, hydrophilic and hydrophobic mixing characteristics are generated, bubbles are easy to appear on the surface of the sapphire substrate, the bubbles can wrap residual phosphoric acid and reactants and are difficult to remove by direct soaking, nitrogen is required to be introduced to enable the water to tumble, and the bubbles are broken by the tumbling, so that the phosphoric acid and the reactants on the surface of the sapphire substrate can be smoothly removed.
More preferably, the temperature of the water is 40 to 50 ℃ to obtain better cleaning effect.
Preferably, the soaking is also followed by rinsing.
Further preferably, the flushing is with water.
Further preferably, the number of times of flushing is 10 to 20.
The invention has the following beneficial effects:
1. according to the method, the sapphire substrate is placed in a phosphoric acid solution with the weight percent of 50-60% for heating, and the boiling point of water is reached at the temperature of 180-350 ℃, so that the water absorbed by phosphoric acid can be boiled, further phosphoric acid is caused to tumble, the phosphoric acid consumed by the surface of the substrate can be supplemented in real time by the tumbling phosphoric acid, dense bubbles are generated, reaction products are taken away, the corrosion intensity and speed of the phosphoric acid are remarkably improved, and an epitaxial layer on the surface of the sapphire substrate can be effectively removed. In addition, after corrosion is finished, the acid liquor losing water can be recovered through standing, and can be recycled, manual intervention is not needed, and the sapphire substrate can be continuously recovered.
2. The invention only needs to use phosphoric acid as a chemical, so that the treatment waste liquid of the method is easy to recycle, and the whole method has low cost and simple operation.
Drawings
Fig. 1 is an optical microscopic view of the sapphire substrate of example 1 and comparative example 1. Wherein a of fig. 1 is an optical microscopic view of the sapphire substrate of example 1, and B of fig. 1 is an optical microscopic view of the sapphire substrate of comparative example 1.
FIG. 2 shows the bubbling phenomenon in the reaction apparatus of example 1.
Fig. 3 is a schematic view showing that bubbles coated with phosphoric acid adhere to and remain on the surface of the sapphire substrate.
Fig. 4 is a photograph or optical microscope image of the sapphire substrate of example 1 before and after recycling. Wherein a of fig. 4 is a photograph of the sapphire substrate of example 1 before recycling, B of fig. 4 is an optical microscope photograph of the sapphire substrate of example 1 at a front edge portion of recycling, C of fig. 4 is an optical microscope photograph of the sapphire substrate of example 1 at a middle portion of the sapphire substrate before recycling, D of fig. 4 is an optical microscope photograph of the sapphire substrate of example 1 at a rear edge portion of recycling, E of fig. 4 is an optical microscope photograph of the sapphire substrate of example 1 at a middle portion of the sapphire substrate after recycling, and F of fig. 4 is a photograph of the sapphire substrate of example 1 after recycling.
Detailed Description
The invention is further illustrated in the following drawings and specific examples, which are not intended to limit the invention in any way. Unless specifically stated otherwise, the reagents, methods and apparatus employed in the present invention are those conventional in the art.
Reagents and materials used in the following examples are commercially available unless otherwise specified.
Example 1A method of recycling sapphire substrate
Placing phosphoric acid in an environment with humidity of 80% to naturally absorb water to a concentration of 50wt%, adding a sapphire substrate with GaN (thickness smaller than 8 μm) on the surface, heating at 300 ℃ for 6h, taking out the sapphire substrate, soaking in deionized water at 45 ℃ for 1.5min, introducing nitrogen into the water while soaking, and flushing with water for 20 times after soaking.
Example 2A method of recycling sapphire substrate
Placing phosphoric acid in an environment with humidity of 50% to naturally absorb water to a concentration of 60wt%, adding a sapphire substrate with InGaN (thickness smaller than 8 μm) on the surface, heating at 180 ℃ for 8h, taking out the sapphire substrate, soaking in deionized water at 50 ℃ for 1min, introducing nitrogen into the water while soaking, and flushing with water for 10 times.
Example 3A method of recycling sapphire substrate
Placing phosphoric acid in an environment with 100% humidity to naturally absorb water to a concentration of 50wt%, adding a sapphire substrate with AlGaN (thickness smaller than 8 μm) on the surface, heating at 350 ℃ for 5h, taking out the sapphire substrate, soaking in deionized water at 40 ℃ for 2min, introducing nitrogen into the water while soaking, and flushing with water for 20 times.
Comparative example 1
Adding a sapphire substrate with GaN (thickness smaller than 8 μm) on the surface into 85wt% phosphoric acid solution, heating at 300 ℃ for 6 hours, taking out the sapphire substrate, soaking in deionized water at 45 ℃ for 1.5min, introducing nitrogen into water while soaking, and flushing with water for 20 times after soaking.
Experimental example 1
At the time of heating for 3 hours, the sapphire substrate of example 1 and the sapphire substrate of comparative example 1 were each subjected to observation under an optical microscope, and the obtained results are shown in fig. 1, wherein a of fig. 1 is an optical microscope image of the sapphire substrate of example 1 and B of fig. 1 is an optical microscope image of the sapphire substrate of comparative example 1. As can be seen from fig. 1, the sapphire substrate surface of example 1 was largely foamed during heating, whereas the sapphire substrate surface of comparative example 1 was free from foaming during heating. In the sapphire recovery method, a large amount of bubbles are quite important for the recovery effect of the sapphire substrate, and because the dense bubbles can take away reaction products, the corrosion strength and the corrosion speed of phosphoric acid are remarkably enhanced, and the epitaxial layer on the surface of the sapphire substrate is removed more efficiently. The invention shows that the recovery treatment of the sapphire substrate by the phosphoric acid with the concentration of 50wt% and natural water absorption can more effectively remove the epitaxial layer on the surface of the sapphire substrate, and the preparation of 85wt% phosphoric acid solution (comparative example 1) can not generate such dense bubbles.
At this time, it is also evident from the observation of the reaction apparatus of example 1 (as shown in FIG. 2) that a large number of dense bubbles exist in the whole reaction apparatus, and the result observed under the optical microscope is further confirmed.
The reason why the bubbles remain on the surface of the sapphire substrate is that the oxidizing property of the phosphoric acid is obviously enhanced at a higher temperature, the surface of the sapphire substrate is modified, the surface of the sapphire substrate is changed from hydrophobicity to hydrophilicity, the bubbles coated with the phosphoric acid remain on the surface of the sapphire substrate in an adhering mode (an adhering schematic diagram is shown in fig. 3), and meanwhile, the residual reactants on the surface of the sapphire substrate are removed in a subsequent soaking and washing link conveniently, so that the subsequent further cleaning is facilitated.
The experimental example also showed the results of the observation of the sapphire substrate of example 1 under an optical microscope before and after the recovery, as shown in fig. 4, wherein a of fig. 4 is a photograph of the sapphire substrate of example 1 before the recovery, B of fig. 4 is an optical microscope photograph of the sapphire substrate of example 1 at the front edge portion before the recovery, C of fig. 4 is an optical microscope photograph of the sapphire substrate of example 1 at the middle portion before the recovery, D of fig. 4 is an optical microscope photograph of the sapphire substrate of example 1 at the rear edge portion after the recovery, E of fig. 4 is an optical microscope photograph of the sapphire substrate of example 1 at the middle portion after the recovery, F of fig. 4 is a photograph of the sapphire substrate of example 1 at the back edge portion after the recovery
And (5) receiving the photo. As can be seen from FIG. 4, after the recovery method of the present invention, the sapphire substrate, either the 5-edge portion or the intermediate portion, is no longer as much contaminated as before recovery, indicating the method of the present invention
The method can effectively remove the epitaxial layer on the surface of the sapphire substrate to obtain the clean and lossless sapphire substrate, improve the recycling rate of the sapphire substrate and reduce the production cost of the sapphire substrate and epitaxial growth.
In addition, the invention also relates to the preparation of the catalyst of example 2 and the implementation of the catalyst before recovery, during the heating for 3 hours and after recovery
The sapphire substrates of example 3 were observed under an optical microscope, respectively, and as a result, the sapphire substrates of example 2 and example 30 were found to be very similar to those of example 1 in that there were many impurities before recycling and during heating
A large number of bubbles are generated, and the method is clean and lossless after recovery, which shows that the method can effectively remove the epitaxial layer on the surface of the sapphire substrate, obtain the clean and lossless sapphire substrate, improve the recycling rate of the sapphire substrate and reduce the production cost of the sapphire substrate and epitaxial growth.
In conclusion, the method of the invention heats the sapphire substrate in 50 to 60 weight percent phosphoric acid solution, and 5 the temperature (180 to 350 ℃) reaches the boiling point of water, so that the water absorbed by phosphoric acid can be boiled, thereby causing
The phosphoric acid is turned over, the phosphoric acid which is turned over can supplement the phosphoric acid consumed by the surface of the substrate in real time, dense bubbles are generated, reaction products are taken away, the corrosion intensity and the corrosion speed of the phosphoric acid are remarkably enhanced, and the epitaxial layer on the surface of the sapphire substrate can be effectively removed. In addition, after corrosion is finished, the acid liquor losing water can be recovered through standing, and can be recycled, manual intervention is not needed, and the sapphire substrate can be continuously recovered.
0 the above examples are preferred embodiments of the present invention, but embodiments of the present invention are not limited to the above embodiments
Any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principles of the invention are intended to be equivalent arrangements for the purpose of the present invention.
Claims (10)
1. A method for recycling a sapphire substrate is characterized in that the sapphire substrate with an epitaxial layer on the surface is taken and placed in a phosphoric acid solution with the weight percent of 50-60% and heated at the temperature of 180-350 ℃.
2. The method of claim 1, wherein the heating is for a period of time ranging from 5 to 8 hours.
3. The method according to claim 1, wherein the preparation of the 50wt% to 60wt% phosphoric acid solution: placing phosphoric acid in an environment with humidity of 50-100% to naturally absorb water until the concentration is 50-60 wt%.
4. The method of claim 1, wherein the epitaxial layer is a gallium nitride based iii-V compound.
5. The method according to claim 4, wherein the gallium nitride-based III-V compound is one or more of GaN, inGaN, alGaN.
6. The method of claim 1, wherein the epitaxial layer has a thickness of less than 8 μm.
7. The method of claim 1, wherein the sapphire substrate is further immersed after the heating.
8. The method of claim 7, wherein the soaking time is 1-2 minutes.
9. The method of claim 7, wherein the soaking is with water.
10. The method of claim 9, wherein the immersing is performed simultaneously with introducing nitrogen gas into the water.
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| CN202211685648.8A CN116072517A (en) | 2022-12-27 | 2022-12-27 | Method for recycling sapphire substrate |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116252188A (en) * | 2023-05-15 | 2023-06-13 | 苏州焜原光电有限公司 | Method for removing epitaxial layer from gallium antimonide epitaxial wafer |
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- 2022-12-27 CN CN202211685648.8A patent/CN116072517A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116252188A (en) * | 2023-05-15 | 2023-06-13 | 苏州焜原光电有限公司 | Method for removing epitaxial layer from gallium antimonide epitaxial wafer |
| CN116252188B (en) * | 2023-05-15 | 2023-08-11 | 苏州焜原光电有限公司 | Method for removing epitaxial layer from gallium antimonide epitaxial wafer |
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