Round corner treatment liquid and method for performing round corner treatment on suede pyramid

Abstract

The invention relates to a round corner treatment liquid and a method for conducting round corner treatment on a suede pyramid. The round corner treatment liquid contains a round corner treatment additive, hydrofluoric acid and water. The content of hydrofluoric acid in the rounding treatment liquid is 1.5-4% by weight, and the content of the rounding additive is 0.5-2.5% by weight; the rounding additive contains a surfactant, sodium citrate, a protective agent, sodium benzoate and a solvent; based on the total weight of the rounding additive, the content of the surfactant is 3.0-6.0 wt%, the content of the sodium citrate is 1.0-4.0 wt%, the content of the protective agent is 3.0-6.0 wt%, the content of the sodium benzoate is 3.0-6.0 wt%, and the content of the solvent is 80-90 wt%. According to the rounding treatment liquid disclosed by the invention, the rounding degree can be effectively controlled, so that the tower tip and the tower valley of a pyramid become smooth at the same time.

Description

Technical Field

[0001] The present application relates to the field of new energy, and in particular, to a rounding treatment liquid and a method for rounding a velvet pyramid. Background Art

[0002] The conventional pyramid morphology modification method is chemical polishing, namely CP (Chemical Polishing), which includes nitric acid CP and ozone CP. Nitric acid CP uses a mixed solution of nitric acid and hydrofluoric acid to etch the textured silicon wafer. The strong oxidizing nitric acid oxidizes silicon into silicon oxide SiO x After that, hydrofluoric acid dissolves it, and the oxidation process and dissolution process are repeated, so that the silicon wafer is gradually etched and the pyramid is gradually smoothed. The etching principle of ozone CP is similar to that of nitric acid CP, except that ozone is used instead of nitric acid as the oxidant.

[0003] The existing rounding treatment methods are difficult to control the degree of rounding, and cannot make the pyramid tip and the pyramid valley smooth at the same time, which affects the deposition of the passivation film in the subsequent process and leads to poor passivation effect. Summary of the invention

[0004] The purpose of the present invention is to provide a rounding treatment liquid and a method for rounding a velvet pyramid, wherein the rounding treatment liquid can effectively control the degree of rounding, so that the top and valley of the pyramid become rounded at the same time.

[0005] In order to achieve the above-mentioned object, the first aspect of the present disclosure provides a filleting treatment liquid, the filleting treatment liquid contains a filleting additive, hydrofluoric acid and water; the content of hydrofluoric acid in the filleting treatment liquid is 1.5-4% by weight, and the content of the filleting additive is 0.5-2.5% by weight; The filleting additive contains a surfactant, sodium citrate, a protective agent, sodium benzoate and a solvent; based on the total weight of the filleting additive, the content of the surfactant is 3.0-6.0% by weight, the content of the sodium citrate is 1.0-4.0% by weight, the content of the protective agent is 3.0-6.0% by weight, the content of the sodium benzoate is 3.0-6.0% by weight, and the content of the solvent is 80-90% by weight.

[0006] Optionally, the content of hydrofluoric acid in the rounded corner treatment solution is 1.5-2.5% by weight, and the content of the rounded corner additive is 0.5-1.5% by weight.

[0007] Optionally, the content of the surfactant is 3-4% by weight, the content of the sodium citrate is 1.0-2.0% by weight, the content of the protective agent is 3-4% by weight, the content of the sodium benzoate is 4-5% by weight, and the content of the solvent is 85-88% by weight.

[0008] Optionally, the content ratio of the surfactant, the sodium citrate, the protective agent, the sodium benzoate and the solvent in the rounded corner additive is 1: (0.5-0.8): (0.8-1.0): (1.2-1.5): (25-30).

[0009] Optionally, the surfactant is selected from one or more of citric acid, alkylphenol polyoxyethylene ether and polyethylene oxide; The protective agent is selected from one or more of sodium hypophosphite, polyglycerol and benzotriazole; The solvent is selected from one or more of water, ethyl vanillin, vanillin and isotridecanol ether.

[0010] Optionally, the content of hydrogen fluoride in the hydrofluoric acid is 45-50% by weight.

[0011] The second aspect of the present disclosure provides a method for rounding corners of velvet pyramids using the rounding treatment liquid provided in the first aspect of the present disclosure, the method comprising: contacting a velvet-making silicon wafer with the rounding treatment liquid for rounding corners.

[0012] Optionally, the rounding treatment conditions include: a time of 30-300 seconds and a temperature of 20-30°C.

[0013] Optionally, the step of contacting the texturing silicon wafer with the corner rounding treatment liquid to perform the corner rounding treatment comprises: immersing the texturing silicon wafer in the corner rounding treatment liquid to perform the corner rounding treatment.

[0014] Optionally, the texturing silicon wafer is prepared by a method comprising the following steps: SS1, after pre-cleaning the silicon wafer by contacting it with a cleaning solution, a clean silicon wafer with organic matter and cutting damage removed is obtained; SS2. The clean silicon wafer is contacted with a texturing agent for texturing treatment and post-cleaning to obtain a texturing silicon wafer.

[0015] Optionally, in step SS2, the texturing agent contains 0.5-5 wt % of KOH, 0.1-1.5 wt % of a texturing additive and a balance of solvent; the texturing treatment conditions include: a temperature of 70-85° C. and a time of 300-600 seconds.

[0016] Through the above technical scheme, the rounding treatment liquid disclosed in the present invention compounds a specific rounding additive and hydrofluoric acid. When it is used for rounding treatment of texturing silicon wafers, it can accurately and effectively control the rounding degree of the pyramid and make the top and bottom of the pyramid rounded, which is beneficial to improving the passivation quality in subsequent processes.

[0017] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 This is a SEM photograph of the textured silicon wafer before rounding treatment in Example 1 of the present disclosure.

[0019] Figure 2 This is a SEM photograph of the textured silicon wafer after rounded corners treatment in Example 1 of the present disclosure. DETAILED DESCRIPTION

[0020] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0021] A first aspect of the present disclosure provides a filleting treatment liquid, which contains a filleting additive, hydrofluoric acid and water; the content of hydrofluoric acid in the filleting treatment liquid is 1.5-4% by weight, and the content of the filleting additive is 0.5-2.5% by weight; the filleting additive contains a surfactant, sodium citrate, a protective agent, sodium benzoate and a solvent; based on the total weight of the filleting additive, the content of the surfactant is 3.0-6.0% by weight, the content of the sodium citrate is 1.0-4.0% by weight, the content of the protective agent is 3.0-6.0% by weight, the content of the sodium benzoate is 3.0-6.0% by weight, and the content of the solvent is 80-90% by weight.

[0022] The rounding treatment liquid disclosed in the present invention contains a rounding additive and hydrofluoric acid. The rounding additive contains specific components. The ratio of the rounding additive and the hydrofluoric acid can be selected according to the rounding needs to accurately and effectively control the rounding degree of the pyramid and round the top and bottom of the pyramid, which is beneficial to improving the passivation quality in subsequent processes.

[0023] In a specific embodiment of the present disclosure, the content of hydrofluoric acid in the rounded corner treatment liquid is 1.5-2.5% by weight, and the content of the rounded corner additive is 0.5-1.5% by weight. In this embodiment, the rounded corner treatment liquid contains 1.5-2.5% by weight of hydrofluoric acid, 0.5-1.5% by weight of the rounded corner additive, and the balance is water.

[0024] In a specific embodiment of the present disclosure, based on the total weight of the rounded corner additive, the content of the surfactant is 3-4 weight %, the content of the sodium citrate is 1.0-2.0 weight %, the content of the protective agent is 3-4 weight %, the content of the sodium benzoate is 4-5 weight %, and the content of the solvent is 85-88 weight %.

[0025] According to the present disclosure, the content ratio of each component in the rounding additive can vary in a wide range. In a preferred embodiment of the present disclosure, the content ratio of the surfactant, the sodium citrate, the protective agent, the sodium benzoate and the solvent in the rounding additive is 1: (0.5-0.8): (0.8-1.0): (1.2-1.5): (25-30).

[0026] According to the present disclosure, the surfactant, protective agent and solvent may be well known to those skilled in the art. In a specific embodiment of the present disclosure, the surfactant is selected from one or more of citric acid, alkylphenol polyoxyethylene ether and polyethylene oxide; the protective agent is selected from one or more of sodium hypophosphite, polyglycerol and benzotriazole; the solvent is selected from one or more of water, ethyl vanillin, vanillin and isotridecanol ether.

[0027] According to the present disclosure, the content of hydrogen fluoride in the hydrofluoric acid may vary within a wide range, for example, may be 45-50% by weight.

[0028] The second aspect of the present disclosure provides a method for rounding corners of velvet pyramids using the rounding treatment liquid provided by the second aspect of the present disclosure, the method comprising: contacting a velvet-making silicon wafer with the rounding treatment liquid for rounding corners.

[0029] The method disclosed in the present invention can accurately and effectively control the degree of rounding of the pyramid, and round the top and bottom of the pyramid, which is beneficial to improving the passivation quality in subsequent processes.

[0030] In a specific embodiment of the present disclosure, the rounding treatment conditions include: time of 30-300 seconds, temperature of 20-30° C.; preferably, time of 100-200 seconds, temperature of 22-26° C. Under this treatment condition, the degree of rounding of the pyramid can be more accurately controlled.

[0031] In a specific embodiment of the present disclosure, the step of contacting the texturing silicon wafer with the corner rounding treatment liquid for corner rounding treatment includes: immersing the texturing silicon wafer in the corner rounding treatment liquid for corner rounding treatment. In this embodiment, the texturing silicon wafer is more fully contacted with the corner rounding treatment liquid, further improving the roundness of the pyramid.

[0032] According to the present disclosure, the preparation method of the textured silicon wafer may be well known to those skilled in the art. In a preferred embodiment, the textured silicon wafer is prepared by a method comprising the following steps: SS1, contacting the silicon wafer with a cleaning solution for pre-cleaning to obtain a clean silicon wafer with organic matter and cutting damage removed; SS2, contacting the clean silicon wafer with a texturing agent for texturing treatment and post-cleaning to obtain a textured silicon wafer.

[0033] In the present disclosure, the cleaning solution in step SS1 is well known to those skilled in the art, and can be, for example, 0.5-5 wt % KOH, 1-10 wt % H 2 O 2 The step further comprises: washing the pre-cleaned silicon wafer with water to obtain a clean silicon wafer with organic matter and cutting damage removed. The present disclosure does not specifically limit the pre-cleaning conditions, which can be selected as needed. In one embodiment, the pre-cleaning conditions include: a temperature of 60-75° C. and a time of 50-300 seconds.

[0034] According to the present disclosure, the texturing treatment in step SS2 is well known to those skilled in the art. In a specific embodiment of the present disclosure, in step SS2, the texturing agent contains 0.5-5 wt% KOH, 0.1-1.5 wt% texturing additive and the remainder solvent. The conditions of the texturing treatment include: a temperature of 70-85°C and a time of 300-600 seconds. The present disclosure does not specifically limit the conditions for post-cleaning, which can be selected as needed. In one embodiment, the conditions for post-cleaning include: a temperature of 60-75°C and a time of 50-300 seconds. The present disclosure does not specifically limit the type of texturing additive, which can be well known to those skilled in the art, for example, it can be a Tobang additive. This step can also include: subjecting the silicon wafer after the texturing treatment to a first water wash, a post-wash and a second water wash in sequence to obtain a clean silicon wafer with organic matter and cutting damage removed.

[0035] In a specific embodiment, after the texturing silicon wafer is contacted with the corner rounding treatment liquid for corner rounding treatment, the treated silicon wafer is pickled, slowly pulled and dried to remove water on the silicon surface.

[0036] The present disclosure is further illustrated below by way of examples, but the present disclosure is not limited thereby.

[0037] Unless otherwise specified, the reagents used in the following examples and comparative examples are all commercially available.

[0038] Example 1 S1. Place the N-type silicon wafer in a solution containing KOH and H 2 O 2 The organic matter and cutting damage on the surface of the N-type silicon wafer were removed by reacting in a cleaning solution of deionized water at 70°C for 200 seconds, and then washed with water to obtain a clean silicon wafer; the cleaning solution used in this process contained 2 wt% KOH and 1 wt% H 2 O 2 The proportion is 5% by weight; S2. Use a texturing agent to texturize the clean silicon wafer and wash it with water. Then use a cleaning solution to clean it at 60°C for 100 seconds to remove organic matter and cutting damage on the surface of the silicon wafer. Then wash it with water to obtain a texturized silicon wafer with a pyramid velvet structure and a reflectivity of 9%. Its SEM photo is as follows: Figure 1 As shown by Figure 1 It can be seen that the pyramid is sharper; the content of KOH in the texturing agent used in this process is 1% by weight, the content of the texturing additive is 0.8% by weight, the temperature of the texturing process is 82°C, and the time of the texturing process is 420 seconds; the content of KOH in the cleaning solution used in this process is 3% by weight, and the content of H 2 O 2 The content is 5% by weight; S3. Immerse the texturing silicon wafer in a filleting treatment solution at 25°C for 250 seconds to perform filleting treatment. The filleting treatment solution contains 2% by weight of hydrofluoric acid, 1% by weight of filleting additive, and a residual amount of water. The content of hydrogen fluoride in the hydrofluoric acid is 45% by weight. Based on the total weight of the filleting additive, the content of citric acid is 3.0% by weight, the content of sodium citrate is 2.0% by weight, the content of sodium hypophosphite is 3.0% by weight, the content of sodium benzoate is 4.0% by weight, and the content of the solvent is 88% by weight.

[0039] S4. The silicon wafer after rounding treatment is placed in HF solution for pickling and slow pulling dehydration treatment, and finally dried. The SEM analysis photos are as follows: Figure 2 As shown in the figure, we can see that the height of the pyramid has obviously become smaller and part of the base has become rounded.

[0040] Example 2 The silicon wafer is rounded using the same method as in Example 1, except that in step S3, the content of hydrofluoric acid in the rounding treatment solution is 3 wt %, and the content of the rounding additive is 2 wt %.

[0041] Example 3 The silicon wafer is rounded using the same method as in Example 1, except that in step S3, the content of citric acid in the rounding additive is 3.3% by weight, the content of sodium citrate is 1.5% by weight, the content of sodium hypophosphite is 3.2% by weight, the content of sodium benzoate is 3.5% by weight, and the content of the solvent is 88.5% by weight.

[0042] Comparative Example 1 The silicon wafer is rounded using the same method as in Example 1, except that in step S3, the rounding additive does not contain sodium citrate. Based on the weight of the rounding additive, the content of citric acid is 4.0 weight %, the content of sodium hypophosphite is 4.0 weight %, the content of sodium benzoate is 4.0 weight %, and the content of the solvent is 88 weight %.

[0043] Comparative Example 2 The silicon wafer is rounded using the same method as in Example 1, except that in step S3, the rounding additive does not contain sodium benzoate, and based on the weight of the rounding additive, the content of citric acid is 4.0 weight %, the content of sodium hypophosphite is 4.0 weight %, the content of sodium citrate is 2.0 weight %, and the content of the solvent is 90 weight %.

[0044] Test Case The silicon wafers prepared in the examples and comparative examples were subjected to the following tests: (1) The emissivity of the silicon wafer before the rounding treatment and the reflectivity of the silicon wafer after the rounding treatment were tested. The specific test method was to use a D8 reflectivity tester for testing. The test results are shown in Table 1.

[0045] (2) The silicon wafer was double-sidedly passivated by plasma enhanced chemical vapor deposition (PECVD) and the minority carrier lifetime, simulated opening voltage and filling performance of the silicon wafer were tested by a minority carrier lifetime tester. The results are shown in Table 2.

[0046] (3) The rounded silicon wafers were subjected to TOPCON process and the battery performance was tested using a battery IV tester. The test results are shown in Table 3.

[0047] Table 1

[0048] Table 2

[0049] Table 3

[0050] The data of Examples 1, 2, 3 and Comparative Examples 1 and 2 in Table 3 are relative values ​​to the silicon wafer before rounding treatment.

[0051] It can be seen from the above that the use of the rounding treatment solution disclosed in the present invention can effectively control the degree of rounding, so that the top of the pyramid and the valley of the pyramid become rounded at the same time, and further make the prepared solar cell have better electrochemical performance.

[0052] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0053] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0054] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A rounding treatment liquid, characterized in that: The filleting treatment liquid contains a filleting additive, hydrofluoric acid and water; the content of hydrofluoric acid in the filleting treatment liquid is 1.5-4% by weight, and the content of the filleting additive is 0.5-2.5% by weight; The filleting additive contains a surfactant, sodium citrate, a protective agent, sodium benzoate and a solvent; based on the total weight of the filleting additive, the content of the surfactant is 3.0-6.0% by weight, the content of the sodium citrate is 1.0-4.0% by weight, the content of the protective agent is 3.0-6.0% by weight, the content of the sodium benzoate is 3.0-6.0% by weight, and the content of the solvent is 80-90% by weight.

2. The rounding treatment liquid according to claim 1, wherein: The content of hydrofluoric acid in the rounded corner treatment liquid is 1.5-2.5% by weight, and the content of the rounded corner additive is 0.5-1.5% by weight.

3. The rounding treatment liquid according to claim 1, wherein: Based on the total weight of the rounded corner additive, the content of the surfactant is 3-4% by weight, the content of the sodium citrate is 1.0-2.0% by weight, the content of the protective agent is 3-4% by weight, the content of the sodium benzoate is 4-5% by weight, and the content of the solvent is 85-88% by weight.

4. The rounding treatment liquid according to claim 1, wherein: The weight ratio of the surfactant, the sodium citrate, the protective agent, the sodium benzoate and the solvent in the filleting additive is 1: (0.5-0.8): (0.8-1.0): (1.2-1.5): (25-30).

5. The rounding treatment liquid according to claim 1, wherein: The surfactant is selected from one or more of citric acid, alkylphenol polyoxyethylene ether and polyethylene oxide; The protective agent is selected from one or more of sodium hypophosphite, polyglycerol and benzotriazole; The solvent is selected from one or more of water, ethyl vanillin, vanillin and isotridecanol ether.

6. The rounding treatment liquid according to claim 1, wherein: The content of hydrogen fluoride in the hydrofluoric acid is 45-50% by weight.

7. A method for rounding a velvet pyramid using the rounding treatment liquid according to any one of claims 1 to 6, characterized in that: The method comprises: contacting the texturing silicon wafer with the corner rounding treatment liquid to perform corner rounding treatment.

8. The method according to claim 7, wherein: The rounding treatment conditions include: a time of 30-300 seconds and a temperature of 20-30°C.

9. The method according to claim 7, wherein: The step of contacting the texturing silicon wafer with the corner rounding treatment liquid to perform the corner rounding treatment comprises: immersing the texturing silicon wafer in the corner rounding treatment liquid to perform the corner rounding treatment.

10. The method according to claim 7, wherein: The texturing silicon wafer is prepared by a method comprising the following steps: SS1, after pre-cleaning the silicon wafer by contacting it with a cleaning solution, a clean silicon wafer with organic matter and cutting damage removed is obtained; SS2. The clean silicon wafer is contacted with a texturing agent for texturing treatment and post-cleaning to obtain a texturing silicon wafer.

11. The method according to claim 10, wherein: In step SS2, the texturing agent contains 0.5-5 wt% KOH, 0.1-1.5 wt% texturing additive and the remainder solvent; the texturing treatment conditions include: temperature of 70-85°C and time of 300-600 seconds.

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