Silicon wafer etching liquid, silicon wafer etching method and silicon wafer
By using a copper metal catalyst silicon wafer etching solution and specific etching methods, the problems of complex silicon wafer etching process, high cost and poor light absorption in the prior art are solved, and silicon wafer preparation with low reflectivity and high light absorption are achieved, thereby improving the efficiency of solar cells.
Patent Information
- Application Number
- CN202411431165.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-14
- Publication Date
- 2025-02-28
AI Technical Summary
The process of preparing nanostructured silicon wafers using metal-assisted catalytic etching is complicated and has high cost. The etched nanostructured silicon wafer has a poor absorption rate of light, which cannot meet the actual application needs.
A silicon wafer etching solution containing a copper metal catalyst is provided. By preparing a specific molar ratio, combined with ultrasonic cleaning, nitric acid diluent soaking and HF solution to remove oxides, silicon wafers with low reflectivity and high light absorption are prepared.
Through the use of copper metal catalyst, an inverted pyramid structure array is formed on the surface of the silicon wafer, which significantly reduces the reflectance to 4%, improves the light absorption rate, improves the photoelectric conversion efficiency of solar cells, and simplifies the etching process and reduces costs.
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Figure CN119529845A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of silicon wafer materials, and in particular to a silicon wafer etching solution, a silicon wafer etching method and a silicon wafer. Background Art
[0002] Constructing nanostructures on the surface of silicon wafers can make the silicon wafers exhibit unique optical and electrical properties. Therefore, they are widely used in sensors, transistors, photovoltaic cells and photodetectors. Silicon wafers with nanostructures have a large surface area, which can increase the number of light reflections and improve the silicon wafer's light absorption rate, thereby generating greater photocurrent and improving the battery's photoelectric conversion efficiency.
[0003] The current process of preparing nanostructured silicon wafers using metal-assisted catalytic etching is complex and costly. The etched nanostructured silicon wafers have poor light absorption and cannot meet the needs of actual applications. Summary of the invention
[0004] In view of this, the purpose of the present application is to propose a silicon wafer etching solution, a silicon wafer etching method and a silicon wafer, so as to solve the problem that the process of preparing nanostructured silicon wafers by using metal-assisted catalytic etching method in the prior art is complicated and costly, and the etched nanostructured silicon wafers have poor light absorption rate and cannot meet the actual application needs.
[0005] Based on the above purpose, the present application provides a silicon wafer etching solution, comprising the following components: H2O2, HF, Cu(NO3)2·3H2O and H2O.
[0006] Furthermore, wherein H2O is a solvent, within a unit volume of the solvent, the molar ratio of H2O2, HF, and Cu(NO3)2·3H2O is 1.8:2.76:(0.02-0.13).
[0007] Furthermore, the molar ratio of H2O2, HF, and Cu(NO3)2·3H2O is 1.8:2.76:0.08.
[0008] Based on the same inventive concept, the present application also provides a silicon wafer etching method.
[0009] A silicon wafer etching method comprises the following steps:
[0010] S1: silicon wafer cleaning: the silicon wafer substrate is ultrasonically cleaned with acetone, ethanol, and deionized water in sequence to obtain a silicon wafer after the first cleaning;
[0011] S2: preparing a nitric acid dilution solution: adding concentrated nitric acid with a mass concentration of 65-68% to ultrapure water in batches to prepare a nitric acid dilution solution, wherein the volume ratio of concentrated nitric acid to ultrapure water is 1:1;
[0012] S3: placing the silicon wafer after the first cleaning in any of the above-mentioned silicon wafer etching solutions for etching to obtain an etched silicon wafer;
[0013] S4: Soaking the etched silicon wafer in a diluted nitric acid solution to remove residual silicon wafer etching solution, and then washing with deionized water to obtain a silicon wafer after the second cleaning;
[0014] S5: Soak the silicon wafer after the second cleaning in an HF solution to remove surface oxides, then rinse with deionized water, and dry to obtain the desired silicon wafer.
[0015] Furthermore, the silicon wafer substrate is an n-type single crystal silicon wafer with a resistivity of 0.01-0.05Ω·cm.
[0016] Furthermore, in step S3, the etching temperature is 40°C.
[0017] Furthermore, in step S3, the etching time is 15 minutes.
[0018] Furthermore, in step S4, the soaking time is 5 minutes.
[0019] Furthermore, in step S5, the mass concentration of the HF solution is 5%, and the immersion time is 3 minutes.
[0020] Based on the same inventive concept, the present application also provides a silicon wafer produced by any of the above-mentioned silicon wafer etching methods.
[0021] Beneficial effects of the present invention:
[0022] 1. The present application provides a silicon wafer etching solution, which contains a copper metal catalyst. The silicon wafer etched by the copper metal catalyst has a good anti-reflection effect, and the reflectivity is as low as 4%. Compared with the silicon wafer etched by the silver catalyst, the reflectivity is reduced by 4.3%. It can be seen that the silicon wafer prepared by the present application has a better anti-reflection effect and a higher light absorption rate. When applied to the field of silicon-based solar cells, it can generate a larger photocurrent by improving the light absorption efficiency, thereby improving the photoelectric conversion efficiency of the battery;
[0023] 2. Compared with the method of etching silicon wafers using metals such as gold and silver as catalysts, the method of etching silicon wafers using copper catalysts in this application is simple, repeatable, and low-cost, which is conducive to the large-scale production of etching silicon wafers. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0025] Figure 1 (a) reflectivity spectrum and (b) light absorption spectrum of the Si wafer obtained in Examples 1-4 of the present application. The concentration of Cu(NO3)2 in the etching solution of Example 1 is 0.02 mol / L; the concentration of Cu(NO3)2 in the etching solution of Example 2 is 0.05 mol / L; the concentration of Cu(NO3)2 in the etching solution of Example 3 is 0.05 mol / L. 3)2 The concentration of Cu(NO3)2 in the etching solution of Example 4 is 0.13 mol / L;
[0026] Figure 2 (a) Reflectivity spectrum and (b) light absorption diagram of Si wafers obtained by catalytic etching under different concentrations of AgNO3;
[0027] Figure 3 Flow chart of Si wafer obtained by Cu catalytic etching. DETAILED DESCRIPTION
[0028] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with specific preparation examples and drawings.
[0029] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0030] As described in the background technology, silicon wafers are a type of semiconductor material with unique electrical properties. Under illumination conditions, silicon wafers can absorb light energy and excite electron-hole pairs, thereby forming current, which is the basis of the photoelectric effect. The semiconductor properties of silicon wafers enable them to exhibit conductivity under illumination, which is an important prerequisite for their application in the optoelectronic field.
[0031] In the optoelectronics field, silicon wafers are widely used in the manufacture of optoelectronic devices such as solar cells, photodiodes, and photodetectors. For example, in solar cells, silicon wafers, as the core material for photoelectric conversion, can convert solar radiation energy into electrical energy to provide power support for various electronic devices. In addition, silicon wafers are also used to manufacture optoelectronic devices in optical fiber communications, such as optical amplifiers and optical modulators, which play an important role in optical fiber communication systems.
[0032] Constructing nanostructures on the surface of silicon wafers can make silicon wafers exhibit unique optical and electrical properties, which has attracted widespread attention in recent years. By constructing nanostructures on the surface of silicon wafers to form light-trapping structures, the light reflectivity of silicon wafers can be reduced and the light absorption rate of silicon wafers can be increased. Applying silicon wafers with nanostructures to the field of silicon-based solar cells can generate greater photocurrent by improving the light absorption efficiency and improve the photoelectric conversion efficiency of the battery. However, the nanostructured silicon wafers prepared by metal-assisted catalytic etching in the prior art have poor light absorption rate and cannot meet the needs of practical applications.
[0033] Based on this, the present application provides a silicon wafer etching solution, which contains a copper metal catalyst. The copper metal catalyst can catalyze the etching process to form an inverted pyramid structure array on the surface of the silicon wafer. The light is reflected multiple times in the pyramid structure, which can increase the silicon wafer's absorption of light and thereby improve the light absorption efficiency. The present application also provides a silicon wafer etching method, which has a simple and repeatable process, and is conducive to the large-scale production of silicon wafers with nanostructures.
[0034] Preparation of silicon wafer etching solution
[0035] Preparation Example 1
[0036] The preparation of silicon wafer etching solution includes the following steps: mixing H2O2 and H2O, stirring evenly, then adding HF, stirring evenly, and finally adding Cu(NO3)2·3H2O, stirring evenly to obtain a light blue clear silicon wafer etching solution, wherein H2O is a solvent, and in a unit solvent volume, the molar ratio of H2O2, HF, and Cu(NO3)2·3H2O is 1.8:2.76:0.02.
[0037] Preparation Example 2
[0038] The preparation of silicon wafer etching solution includes the following steps: mixing H2O2 and H2O, stirring evenly, then adding HF, stirring evenly, and finally adding Cu(NO3)2·3H2O, stirring evenly to obtain a light blue clear silicon wafer etching solution, wherein H2O is a solvent, and in a unit solvent volume, the molar ratio of H2O2, HF, and Cu(NO3)2·3H2O is 1.8:2.76:0.05.
[0039] Preparation Example 3
[0040] The preparation of silicon wafer etching solution includes the following steps: mixing H2O2 and H2O, stirring evenly, then adding HF, stirring evenly, and finally adding Cu(NO3)2·3H2O, stirring evenly to obtain a light blue clear silicon wafer etching solution, wherein H2O is a solvent, and in a unit solvent volume, the molar ratio of H2O2, HF, and Cu(NO3)2·3H2O is 1.8:2.76:0.08.
[0041] Preparation Example 4
[0042] The preparation of silicon wafer etching solution includes the following steps: mixing H2O2 and H2O, stirring evenly, then adding HF, stirring evenly, and finally adding Cu(NO3)2·3H2O, stirring evenly to obtain a light blue clear silicon wafer etching solution, wherein H2O is a solvent, and in a unit solvent volume, the molar ratio of H2O2, HF, and Cu(NO3)2·3H2O is 1.8:2.76:0.13.
[0043] Example
[0044] Example 1
[0045] A silicon wafer etching method comprises the following steps:
[0046] S1: First cleaning of silicon wafer: ultrasonically cleaning the silicon wafer substrate with acetone, ethanol and deionized water in sequence to obtain a silicon wafer after the first cleaning, wherein the silicon wafer substrate is an n-type single crystal silicon wafer with a resistivity of 0.01-0.05Ω·cm;
[0047] S2: preparing a nitric acid dilution solution: adding concentrated nitric acid with a mass concentration of 65-68% to ultrapure water in batches to prepare a nitric acid dilution solution, wherein the volume ratio of concentrated nitric acid to ultrapure water is 1:1;
[0048] S3: silicon wafer etching: placing the silicon wafer after the first cleaning in a silicon wafer etching solution (from Preparation Example 1) for etching, the temperature of the silicon wafer etching solution is 40° C., the etching time is 15 min, and an etched silicon wafer is obtained;
[0049] S4: Second cleaning of the silicon wafer: Soak the etched silicon wafer in a diluted nitric acid solution for 5 minutes to remove the residual silicon wafer etching solution, and then rinse with deionized water to obtain a silicon wafer after the second cleaning;
[0050] S5: Removing oxides from the surface of the silicon wafer: Soak the silicon wafer after the second cleaning in a 5% HF solution for 3 minutes to remove surface oxides, then rinse with deionized water, and dry to obtain the desired silicon wafer.
[0051] Example 2
[0052] The difference between Example 2 and Example 1 is that the silicon wafer etching solution comes from Preparation Example 2, and the remaining steps are the same as Example 1.
[0053] Example 3
[0054] The difference between Example 3 and Example 1 is that the silicon wafer etching solution comes from Preparation Example 3, and the remaining steps are the same as Example 1.
[0055] Example 4
[0056] The difference between Example 4 and Example 1 is that the silicon wafer etching solution comes from Preparation Example 4, and the remaining steps are the same as Example 1.
[0057] Comparative Example
[0058] Comparative Example 1
[0059] A silicon wafer etching method comprises the following steps:
[0060] S1: silicon wafer cleaning: ultrasonically cleaning the silicon wafer substrate with acetone, ethanol, and deionized water in sequence to obtain a silicon wafer after the first cleaning, wherein the silicon wafer substrate is an n-type single crystal silicon wafer with a resistivity of 0.01-0.05Ω·cm;
[0061] S2: Prepare deposition solution: weigh 0.008, 0.017, 0.051 and 0.085 g of AgNO3, respectively, add 10 mL of ultrapure water, and stir magnetically at room temperature for 10 min to obtain AgNO3 solutions with concentrations of 0.005 mol / L, 0.01 mol / L, 0.03 mol / L and 0.05 mol / L, then add 13.44 g of 4.8 mol / L HF solution, respectively, and stir magnetically at room temperature for 15 min to obtain four clear and transparent deposition solutions with different concentrations;
[0062] S3: preparing an etching solution: mixing an HF solution with a concentration of 4.8 mol / L, an H2O2 solution with a concentration of 0.4 mol / L and high-purity water to prepare an etching solution, wherein the mass ratio of the HF solution, the H2O2 solution and the high-purity water is 1:2:5;
[0063] S4: Deposition of AgNPs (silver nanoparticles): Place the cleaned silicon wafer in the deposition solution under light-shielding conditions and let it stand for 1 min before taking it out to form a uniform gray-white particle film on the surface of the silicon wafer. Rinse the deposition solution with deionized water and dry it at 60°C in vacuum for 1 h to obtain a silicon wafer with AgNPs deposited.
[0064] S5: Etching silicon wafer: Put the silicon wafer with AgNPs deposited into the etching solution and etch for 30 minutes at 20°C. After that, take it out and clean the etching solution with deionized water, then immerse it in a diluted nitric acid solution for 1 hour to remove the AgNPs remaining on the surface, wash it with deionized water again and dry it, then immerse the silicon wafer in a 5% HF solution for 3 minutes to remove the oxide layer, wash it with deionized water and dry it to obtain the desired silicon wafer.
[0065] Results Analysis
[0066] 1. The surface structure of the silicon wafer after etching can be observed by scanning electron microscopy. When scanning the silicon wafer obtained by Cu catalytic etching with a scanning electron microscope, it can be observed that the surface of the silicon wafer presents an inverted pyramid structure. When scanning the silicon wafer obtained by Ag catalytic etching with a scanning electron microscope, it can be observed that the surface of the silicon wafer presents a surface nanowire array structure.
[0067] 2. Test the light reflectivity and light absorption rate of the silicon wafer after etching by UV-Vis-NIR absorption spectroscopy. The specific data are as follows: Figure 1 and Figure 2 As shown, it has been confirmed by conventional techniques in this field. Figure 1 The content of Cu(NO3)2 in the etching solution is selected to be 0.02-0.13 mol / L. Figure 2 The content of AgNO3 in the etching solution is selected to be 0.005-0.05 mol / L;
[0068] like Figure 1 As shown, the silicon wafer was tested by UV-visible-near infrared absorption spectroscopy. The results showed that the best anti-reflection effect of silicon wafer was obtained by catalytic etching at a concentration of 0.08 mol / LCu(NO3)2, with a reflectivity of about 4% and the highest light absorption efficiency. Figure 2 As shown in the figure, the anti-reflection effect of the silicon wafer obtained by catalytic etching at a concentration of 0.03 mol / LAgNO3 is the best, the reflectivity light absorption rate is 8.3%, and the light absorption efficiency is the largest. Therefore, compared with the silicon wafer catalytically etched by the silver metal catalyst, the silicon wafer catalytically etched by the copper metal catalyst has a lower reflectivity, a better anti-reflection effect, and a greater light absorption rate. This is mainly because the surface of the silicon wafer catalytically etched by the silver metal catalyst presents a nanowire array structure, while the surface of the silicon wafer catalytically etched by the copper metal catalyst presents an inverted pyramid structure. Compared with the nanowire array structure, light can be reflected multiple times in the pyramid structure, thereby increasing the silicon wafer's absorption of light, thereby improving the light absorption efficiency.
[0069] It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.
[0070] Although the present application has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art in light of the foregoing description.
[0071] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the present application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the protection scope of the present application.
Claims
1. A silicon wafer etching solution, characterized in that: It includes the following components: H2O2, HF, Cu(NO3)2·3H2O and H2O.
2. A silicon wafer etching solution according to claim 1, characterized in that: in, H2O is a solvent, and within a unit volume of the solvent, the molar ratio of H2O2, HF, and Cu(NO3)2·3H2O is 1.8:2.76:(0.02-0.13).
3. A silicon wafer etching solution according to claim 2, characterized in that: In a unit volume of solvent, the molar ratio of H2O2, HF, and Cu(NO3)2·3H2O is 1.8:2.76:0.
08.
4. A silicon wafer etching method, characterized in that: The following steps are involved: S1: First cleaning of silicon wafer: ultrasonically clean the silicon wafer substrate with acetone, ethanol and deionized water in sequence to obtain a silicon wafer after the first cleaning; S2: preparing a nitric acid dilution solution: adding concentrated nitric acid with a mass concentration of 65-68% to ultrapure water in batches to prepare a nitric acid dilution solution, wherein the volume ratio of concentrated nitric acid to ultrapure water is 1:1; S3: silicon wafer etching: placing the silicon wafer after the first cleaning in the silicon wafer etching solution according to any one of claims 1 to 3 for etching to obtain an etched silicon wafer; S4: Second cleaning of the silicon wafer: Soak the etched silicon wafer in a diluted nitric acid solution to remove residual silicon wafer etching solution, and then rinse with deionized water to obtain a silicon wafer after the second cleaning; S5: Removing oxides from the surface of the silicon wafer: Soaking the silicon wafer after the second cleaning in an HF solution to remove surface oxides, then washing it with deionized water, and drying it to obtain the desired silicon wafer.
5. A silicon wafer etching method according to claim 4, characterized in that: The silicon wafer substrate is an n-type single crystal silicon wafer with a resistivity of 0.01-0.05Ω·cm.
6. A silicon wafer etching method according to claim 4, characterized in that: In step S3, the etching temperature is 40°C.
7. A silicon wafer etching method according to claim 4, characterized in that: In step S3, the etching time is 15 minutes.
8. A silicon wafer etching method according to claim 4, characterized in that: In step S4, the soaking time is 5 minutes.
9. A silicon wafer etching method according to claim 4, characterized in that: In step S5, the mass concentration of the HF solution is 5%, and the immersion time is 3 minutes.
10. A silicon wafer, characterized in that: The silicon wafer is prepared by the silicon wafer etching method according to any one of claims 4 to 9.