Silicon wafer cleaning and texturing method, silicon wafer cleaning and texturing equipment, textured silicon wafer and solar cell
By employing a two-stage cleaning method (high-alkali and low-alkali) during the silicon wafer cleaning and texturing process, and maintaining the high-alkali cleaning solution concentration by replenishing with low-alkali cleaning solution, the problem of high consumable costs in traditional cleaning methods is solved, achieving savings in consumable usage and improved cleaning effect.
Patent Information
- Application Number
- CN202410560412.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-07
- Publication Date
- 2025-11-18
AI Technical Summary
The high cost of consumables in traditional silicon wafer cleaning and texturing processes is mainly due to the need for frequent replacement of the cleaning solution and its high concentration, resulting in a large amount of consumables used.
A two-stage silicon wafer cleaning method is adopted. First, a high-alkalinity, high-alkali cleaning solution is used for high-alkali cleaning treatment, followed by a low-alkali cleaning solution for low-alkali cleaning treatment. The low-alkali cleaning solution is used as a replenishing solution to maintain the mass concentration of alkali in the high-alkali cleaning solution.
It effectively reduced the amount of consumables used, especially hydrogen peroxide, while ensuring the cleaning effect and cleanliness of the silicon wafer surface.
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Figure CN120980995A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of photovoltaic technology, and in particular to a silicon wafer cleaning and texturing method, a device, a textured silicon wafer and a solar cell. BACKGROUND
[0002] In the production process of crystalline silicon solar cells, a silicon wafer usually needs a texturing process. The texturing process utilizes the anisotropic etching characteristics of a silicon wafer in an alkaline solution to form a "pyramid" light-trapping structure on the surface of the silicon wafer, also known as a "textured surface structure". The textured surface structure can reduce the reflectivity of the surface of the silicon wafer and increase the amount of light absorbed by the silicon wafer, thereby improving the conversion efficiency. The texturing process in a broad sense not only includes the step of placing a silicon wafer in a texturing alkaline solution to form a textured surface structure, but also includes the step of cleaning the silicon wafer before forming the textured surface structure. The purpose of the cleaning process is to remove stains attached to the surface of the silicon wafer and to remove a damage layer generated on the surface of the silicon wafer during the cutting process. In the conventional technology, a mixed solution containing alkali and hydrogen peroxide is usually used to clean the silicon wafer. In the conventional cleaning process, an initial cleaning solution is usually added to a cleaning tank, and as the number of cleaning times increases, a replenishing solution needs to be added to the cleaning tank multiple times to maintain the concentration of alkali in the cleaning tank and ensure the cleaning effect. The conventional cleaning method consumes a large amount of consumables, resulting in a high cost of consumables required for the silicon wafer cleaning and texturing process. SUMMARY
[0003] Therefore, in view of the above background, it is necessary to provide a silicon wafer cleaning and texturing method that can save consumables while ensuring the cleaning effect, thereby reducing the production cost of the silicon wafer cleaning and texturing process.
[0004] According to some embodiments of the present application, a silicon wafer cleaning and texturing method is provided, which includes the following steps: placing a silicon wafer in a high-alkali cleaning solution for high-alkali cleaning treatment, transferring the silicon wafer subjected to the high-alkali cleaning treatment to a low-alkali cleaning solution for low-alkali cleaning treatment, and transferring the silicon wafer subjected to the low-alkali cleaning treatment to a texturing solution for texturing treatment, wherein the mass concentration of alkali in the low-alkali cleaning solution is less than the mass concentration of alkali in the high-alkali cleaning solution.
[0005] The silicon wafer cleaning and texturing method further includes replenishing the high-alkali cleaning solution, which includes adding the low-alkali cleaning solution as a replenishing solution to the high-alkali cleaning solution and adding alkali to the high-alkali cleaning solution to maintain the mass concentration of alkali in the high-alkali cleaning solution.
[0006] In some embodiments of the present application, the mass concentration of alkali in the high-alkali cleaning solution is 0.19% to 0.37%.
[0007] In some embodiments of the present application, the mass concentration of the alkali in the low-alkali cleaning solution is 0.06% to 0.12%.
[0008] In some embodiments of the present application, the solute of the high-alkali cleaning solution and the low-alkali cleaning solution further comprises hydrogen peroxide, the mass concentration of the hydrogen peroxide in the high-alkali cleaning solution is less than 0.5wt%, and the mass concentration of the hydrogen peroxide in the low-alkali cleaning solution is less than 0.5wt%.
[0009] In some embodiments of the present application, the mass concentration of the hydrogen peroxide in the high-alkali cleaning solution is 0.34% to 0.5%.
[0010] In some embodiments of the present application, the mass concentration of the hydrogen peroxide in the low-alkali cleaning solution is 0.34% to 0.5%.
[0011] In some embodiments of the present application, during the high-alkali cleaning process, the temperature of the high-alkali cleaning solution is controlled to be 65°C to 70°C, and the cleaning time is controlled to be 150s to 180s.
[0012] In some embodiments of the present application, during the low-alkali cleaning process, the temperature of the low-alkali cleaning solution is controlled to be 65°C to 70°C, and the cleaning time is controlled to be 150s to 180s.
[0013] Further, the present application also provides a silicon wafer cleaning and texturing device, which comprises a high-alkali cleaning tank, a low-alkali cleaning tank and a texturing tank, the high-alkali cleaning tank is used for containing a high-alkali cleaning solution, the low-alkali cleaning tank is used for containing a low-alkali cleaning solution, the texturing tank is used for containing a texturing solution, the high-alkali cleaning tank, the low-alkali cleaning tank and the texturing tank are sequentially arranged on a conveying path of the silicon wafer, and the low-alkali cleaning tank is communicated with the high-alkali cleaning tank.
[0014] In some embodiments of the present application, the low-alkali cleaning solution storage device is connected to the high-alkali cleaning tank and the low-alkali cleaning tank, and is used for transferring the low-alkali cleaning solution in the low-alkali cleaning tank to the high-alkali cleaning tank.
[0015] In some embodiments of the present application, the low-alkali cleaning solution storage device comprises a liquid storage container, a liquid discharge pipe and a liquid pumping pump, the liquid storage container is used for receiving the low-alkali cleaning solution in the low-alkali cleaning tank, the liquid discharge pipe is connected to the liquid storage container and the high-alkali cleaning tank, and the liquid pumping pump is used for pumping the low-alkali cleaning solution to the high-alkali cleaning tank.
[0016] Further, the present application also provides a texturing silicon wafer, which is obtained by the silicon wafer cleaning and texturing method in the above embodiments.
[0017] Further, the application also provides a solar cell comprising the texturized silicon wafer in the above-mentioned embodiments.
[0018] In the conventional technology, the silicon wafer is usually cleaned once to remove the dirt and damage layer on the surface of the silicon wafer. However, the concentration of the cleaning product generated by the reaction between the silicon wafer and the cleaning liquid gradually increases and adheres to the surface of the silicon wafer after the cleaning liquid is used to clean a certain amount of silicon wafers, which affects the cleaning effect of the silicon wafer. Therefore, in order to improve the cleanliness of the surface of the silicon wafer, the cleaning liquid needs to be frequently replaced and a cleaning liquid with a high alkali concentration is usually used in the conventional technology, which greatly increases the consumption of the cleaning liquid.
[0019] In the silicon wafer cleaning and texturizing method of the application, the high-alkali cleaning liquid is used for high-alkali cleaning treatment, and then the low-alkali cleaning liquid is used for low-alkali cleaning treatment. The alkali concentration in the high-alkali cleaning liquid is relatively high, which can quickly remove most of the damage layer and oil stains. The alkali concentration in the low-alkali cleaning liquid is relatively low, which is used for micro-etching cleaning of the silicon wafer to improve the cleaning quality of the silicon wafer. The silicon wafer cleaning and texturizing method proposes a twice cleaning mode, which concentrates most of the dirt and reaction product in the high-alkali cleaning liquid and keeps the low-alkali cleaning liquid relatively clean. On this basis, the low-alkali cleaning liquid is used as the supplement of the high-alkali cleaning liquid, which can effectively reduce the consumption of the consumables while ensuring the cleaning effect.
[0020] The above description is only a summary of the technical scheme of the application. In order to more clearly understand the technical means of the application and can be implemented according to the content of the specification, the following will be described in detail with the preferred embodiments of the application. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 It is a step schematic diagram of a silicon wafer cleaning and texturizing method.
[0022] Figure 2 It is a tank structure schematic diagram of a silicon wafer cleaning and texturizing device.
[0023] Figure 3 It is Figure 2 The communication structure schematic diagram of the low-alkali cleaning tank and the high-alkali cleaning tank in the application.
[0024] In the drawings, the reference signs and their meanings are as follows:
[0025] 111, high-alkali cleaning tank; 112, low-alkali cleaning tank; 113, liquid storage container; 114, liquid pumping pump; 115, liquid discharge pipe; 210, first water washing tank; 120, texturizing tank; 130, alkali washing tank; 140, acid washing tank; 150, slow pulling tank; 160, drying device; 220, second water washing tank; 230, third water washing tank; 240, fourth water washing tank. DETAILED DESCRIPTION
[0026] For the purposes of this document, a more complete description of the text will be provided below. The preferred embodiments of the text are given in the text. However, the text can be implemented in many different forms and is not limited to the embodiments described in the text. On the contrary, the purpose of providing these embodiments is to make the content of the text more thorough and comprehensive.
[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the text belongs. The terms used in the specification of the text are only for the purpose of describing specific embodiments and are not intended to limit the text.
[0028] The purpose of the terms used herein is only to describe specific embodiments and not as a limitation of the disclosure. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprise" and / or "include", when used in the specification, determine the presence of a feature, integer, step, operation, element and / or component, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups. As used herein, the term "and / or" includes any and all combinations of the related listed items.
[0029] The present disclosure provides a silicon wafer cleaning and texturing method, which comprises the following steps: placing a silicon wafer in a high-alkali cleaning solution for high-alkali cleaning treatment, transferring the silicon wafer subjected to the high-alkali cleaning treatment to a low-alkali cleaning solution for low-alkali cleaning treatment, and transferring the silicon wafer subjected to the low-alkali cleaning treatment to a texturing solution for texturing treatment, wherein the mass concentration of alkali in the low-alkali cleaning solution is less than the mass concentration of alkali in the high-alkali cleaning solution. The silicon wafer cleaning and texturing method further comprises: performing a liquid supplementing treatment on the high-alkali cleaning solution, which comprises: adding the low-alkali cleaning solution as a supplement to the high-alkali cleaning solution, and supplementing alkali to the high-alkali cleaning solution to maintain the mass concentration of alkali in the high-alkali cleaning solution.
[0030] In the conventional technology, the silicon wafer is usually subjected to only one cleaning treatment, and the purpose of removing the dirt and damage layer attached to the surface of the silicon wafer is achieved in the cleaning process. However, after the cleaning solution is used to clean a certain number of silicon wafers, the concentration of the cleaning products generated by the reaction between the silicon wafer and the cleaning solution also gradually increases and is attached to the surface of the silicon wafer, which affects the cleaning effect of the silicon wafer. Therefore, in order to improve the cleanliness of the surface of the silicon wafer, it is usually necessary to frequently replace the cleaning solution and use a cleaning solution with a higher alkali concentration in the conventional technology, which greatly increases the consumption of the cleaning solution.
[0031] In the silicon wafer cleaning and texturing method of the present application, high-alkali cleaning treatment is first performed using a high-alkali cleaning solution, and then low-alkali cleaning treatment is performed using a low-alkali cleaning solution. The alkali concentration in the high-alkali cleaning solution is relatively high, which can quickly remove most of the damage layer and oil stains. The alkali concentration in the low-alkali cleaning solution is relatively low, which is used for micro-etching cleaning of the silicon wafer to improve the cleaning quality of the silicon wafer. The silicon wafer cleaning and texturing method proposes a two-time cleaning mode, which concentrates most of the stains and reaction products in the high-alkali cleaning solution, and keeps the low-alkali cleaning solution relatively clean. On this basis, the low-alkali cleaning solution is used as a replenishment of the high-alkali cleaning solution, which can effectively reduce the amount of consumables used while ensuring the cleaning effect.
[0032] It can be understood that in the cleaning and texturing process, the high-alkali cleaning treatment is to remove most of the damage layer and most of the stains on the silicon wafer, and accordingly, the high-alkali cleaning solution will gradually accumulate more cleaning products and stains during the cleaning process. The role of the low-alkali cleaning treatment is to perform micro-etching cleaning of the silicon wafer to improve the cleaning quality of the silicon wafer, and accordingly, the cleaning products and stains in the low-alkali cleaning solution are less, so the low-alkali cleaning solution can be kept in a relatively clean state.
[0033] In a first aspect, the present application provides a cleaning and texturing process for a silicon wafer surface.
[0034] Figure 1 A step schematic diagram of a silicon wafer cleaning and texturing method of the present application is shown. Referring to Figure 1 The silicon wafer cleaning and texturing method includes steps S1-S3, which are as follows.
[0035] Step S1, placing the silicon wafer in a high-alkali cleaning solution for high-alkali cleaning treatment.
[0036] In some examples of this embodiment, the solutes in the high-alkali cleaning solution can include alkali and hydrogen peroxide. In the cleaning process, the hydrogen peroxide is mainly used for oxidation treatment of the damage layer of the silicon wafer and the stains attached to the silicon wafer, and the alkali is mainly used for dissolving the oxidation products, so as to achieve the effect of removing the stains and the damage layer. The high-alkali cleaning solution used for cleaning the stains on the surface of the silicon wafer usually contains cleaning products, which include dissolved organic matter and by-products, particulate contaminants, a small amount of metal ions and silicate ions in the silicon wafer.
[0037] In some examples of this embodiment, the alkali in the high-alkali cleaning solution is selected from strong alkalis. For example, the alkali in the high-alkali cleaning solution can include one or more of sodium hydroxide and potassium hydroxide. In this embodiment, the alkali in the high-alkali cleaning solution can be sodium hydroxide.
[0038] In some examples of the embodiment, the mass concentration of the alkali in the high-alkali cleaning solution can be 0.19% to 0.37%. Setting the mass concentration of the alkali in the high-alkali cleaning solution to 0.19% to 0.37% can effectively etch the silicon wafer and remove most of the damage layer on the surface of the silicon wafer. It can be understood that, in the actual cleaning process, the mass concentration of the alkali in the high-alkali cleaning solution can be dynamically changed, which can decrease after reacting with the silicon wafer, and can increase after replenishing the solution. The range of the mass concentration of the alkali can be controlled by controlling the replenishing time and the replenishing amount.
[0039] In the embodiment, the way of placing the silicon wafer in the high-alkali cleaning solution for high-alkali cleaning treatment can be: immersing the silicon wafer in the high-alkali cleaning solution to perform high-alkali cleaning treatment on the silicon wafer.
[0040] In some examples of the embodiment, the mass concentration of hydrogen peroxide in the high-alkali cleaning solution is below 0.5wt%. The mass concentration of hydrogen peroxide in the cleaning solution used in the conventional technology usually needs to reach above 0.8wt%. However, in the embodiment, the high-alkali cleaning treatment and the low-alkali cleaning treatment can reduce the concentration requirement of hydrogen peroxide in the high-alkali cleaning solution to below 0.5% under the premise of ensuring the cleanliness of the surface of the silicon wafer, thereby saving the amount of hydrogen peroxide.
[0041] In some examples of the embodiment, the mass concentration of hydrogen peroxide in the high-alkali cleaning solution can be controlled to be 0.34% to 0.5%. It can be understood that, in the actual cleaning process, the mass concentration of hydrogen peroxide in the high-alkali cleaning solution can be dynamically changed, which can decrease after reacting with the silicon wafer, and can increase after replenishing the solution. The range of the mass concentration of hydrogen peroxide can be controlled by controlling the replenishing time and the replenishing amount.
[0042] In some examples of the embodiment, the temperature of the high-alkali cleaning solution can be controlled to be 65°C to 70°C during the high-alkali cleaning treatment. For example, the temperature of the high-alkali cleaning solution can be controlled to be 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, or the temperature of the high-alkali cleaning solution can be controlled to be within a range between any two of the above temperatures.
[0043] In some examples of the embodiment, the cleaning time can be controlled to be 150s to 180s during the high-alkali cleaning treatment. For example, the cleaning time can be controlled to be 150s, 155s, 160s, 165s, 170s, 175s, 180s, or the cleaning time can be controlled to be within a range between any two of the above times. Controlling the temperature and the time of the high-alkali cleaning treatment within the range ensures that most of the stains on the surface of the silicon wafer are removed in the process of high-alkali cleaning.
[0044] Step S2, the silicon wafer after the high-alkali cleaning treatment is placed in the low-alkali cleaning solution for low-alkali cleaning treatment.
[0045] In this embodiment, the solute in the low-alkali cleaning solution includes alkali and hydrogen peroxide, and the mass concentration of the alkali in the low-alkali cleaning solution is less than the mass concentration of the alkali in the high-alkali cleaning solution.
[0046] The purpose of the low-alkali cleaning treatment is mainly to slightly etch the silicon wafer to ensure the cleaning quality. The low-alkali cleaning solution usually also contains cleaning products, including dissolved organic matter and by-products, particulate contaminants, a small amount of metal ions and silicate ions. It can be understood that controlling the low mass concentration of the alkali in the low-alkali cleaning solution is conducive to reducing the cleaning products in the low-alkali cleaning solution, ensuring that the low-alkali cleaning solution is relatively clean, so that the low-alkali cleaning solution can meet the demand of being a replenishing solution of the high-alkali cleaning solution.
[0047] In some examples of this embodiment, the alkali in the low-alkali cleaning solution is selected from strong alkalis. For example, the alkali in the low-alkali cleaning solution can include one or more of sodium hydroxide and potassium hydroxide. In this embodiment, the alkali in the low-alkali cleaning solution can be sodium hydroxide.
[0048] In some examples of this embodiment, the mass concentration of the alkali in the low-alkali cleaning solution is set to 0.06% to 0.12%. Using the low-alkali cleaning solution with a mass concentration of the alkali between 0.06% and 0.12% can reduce the cleaning products in the low-alkali cleaning solution as much as possible while ensuring good cleaning effect. It can be understood that in the actual cleaning process, the mass concentration of the alkali in the low-alkali cleaning solution can be dynamically changed, which will decrease after reacting with the silicon wafer, and can rise again after replenishment. The range of the mass concentration of the alkali can be controlled by controlling the replenishment time and the replenishment amount, etc.
[0049] In this embodiment, the way of placing the silicon wafer in the low-alkali cleaning solution for low-alkali cleaning treatment can be: immersing the silicon wafer in the low-alkali cleaning solution to perform low-alkali cleaning treatment on the silicon wafer.
[0050] In some examples of the embodiment, the mass concentration of hydrogen peroxide in the low-alkali cleaning solution is less than 0.5 wt%. Controlling the mass concentration of hydrogen peroxide in the low-alkali cleaning solution to be less than 0.5 wt% can ensure good cleaning effect while saving the amount of hydrogen peroxide used, thereby reducing the cost of consumables. In some examples of the embodiment, the difference between the mass concentration of hydrogen peroxide in the high-alkali cleaning solution and the mass concentration of hydrogen peroxide in the low-alkali cleaning solution is less than or equal to 0.1%. Controlling the mass concentration of hydrogen peroxide in the low-alkali cleaning solution to be close to the mass concentration of hydrogen peroxide in the high-alkali cleaning solution can ensure effective removal of organic stains while removing minor damage. In addition, setting the mass concentration of hydrogen peroxide in the high-alkali cleaning solution and the low-alkali cleaning solution to be close to each other can also avoid the need to supplement additional hydrogen peroxide into the high-alkali cleaning solution when the low-alkali cleaning solution is discharged into the high-alkali cleaning solution.
[0051] In some examples of the embodiment, the mass concentration of hydrogen peroxide in the low-alkali cleaning solution can be controlled to be 0.34% to 0.5%. It can be understood that in the actual cleaning process, the mass concentration of hydrogen peroxide in the low-alkali cleaning solution can be dynamically changed, which can decrease after reacting with the silicon wafer, and can increase after replenishing the solution. The range of the mass concentration of hydrogen peroxide can be controlled by controlling the replenishment time and the amount of replenishment.
[0052] In some examples of the embodiment, during the low-alkali cleaning process, the temperature of the low-alkali cleaning solution can be controlled to be 65°C to 70°C. For example, the temperature of the low-alkali cleaning solution can be controlled to be 65°C, 66°C, 67°C, 68°C, 69°C, or 70°C, or the temperature of the low-alkali cleaning solution can be controlled to be within a range between any two of the above temperatures.
[0053] In some examples of the embodiment, during the low-alkali cleaning process, the cleaning time can be controlled to be 150s to 180s. For example, the cleaning time can be controlled to be 150s, 155s, 160s, 165s, 170s, 175s, or 180s, or the cleaning time can be controlled to be within a range between any two of the above times. Controlling the temperature and time of the low-alkali cleaning process within the range is beneficial to ensuring the cleanliness of the surface of the silicon wafer.
[0054] In the embodiment, during the use of the high-alkali cleaning solution and the low-alkali cleaning solution, the method further includes a replenishment treatment of the high-alkali cleaning solution, the replenishment treatment including adding the low-alkali cleaning solution as replenishment into the high-alkali cleaning solution, and supplementing alkali into the high-alkali cleaning solution to maintain the mass concentration of alkali in the high-alkali cleaning solution.
[0055] It can be understood that, as the cleaning process gradually proceeds, the alkali and hydrogen peroxide in the high-alkali cleaning solution will be consumed during use, resulting in a gradual decrease in the concentration of solutes in the high-alkali cleaning solution, and a gradual increase in the cleaning products. In this embodiment, the concentration of alkali in the low-alkali cleaning solution is relatively low, and its main role is to perform a micro-etching treatment on the silicon wafer, so the amount of cleaning products in the low-alkali cleaning solution is obviously less, and it can still ensure that the high-alkali cleaning solution has good cleaning effect when it is used as a supplement for the high-alkali cleaning solution. Since the mass concentration of alkali in the low-alkali cleaning solution is relatively low, alkali needs to be supplemented to the high-alkali cleaning solution to maintain the mass concentration of alkali in the high-alkali cleaning solution. The alkali used for supplementing can be an alkali solution with a higher alkali concentration than the high-alkali cleaning solution.
[0056] In this embodiment, the low-alkali cleaning solution is used to supplement the high-alkali cleaning solution, which can save materials. If the low-alkali cleaning solution and the high-alkali cleaning solution are supplemented respectively, not only can materials not be saved, but also the use of materials will increase due to two-step cleaning.
[0057] It can be understood that, when the low-alkali cleaning solution is discharged into the high-alkali cleaning solution, whether hydrogen peroxide needs to be supplemented can be determined according to the concentration of the high-alkali cleaning solution detected. For example, in this embodiment, the mass concentration of hydrogen peroxide in the low-alkali cleaning solution is the same as that in the high-alkali cleaning solution, so there is no need to supplement hydrogen peroxide to the high-alkali cleaning solution additionally.
[0058] In this embodiment, when the low-alkali cleaning solution is discharged into the high-alkali cleaning solution, only part of the low-alkali cleaning solution can be discharged. After the low-alkali cleaning solution is discharged, the low-alkali cleaning solution can be supplemented to maintain the mass concentration of each solute in the low-alkali cleaning solution within a required range. When the low-alkali cleaning solution is supplemented, a supplementing solution that can be used to maintain the mass concentration of solutes in the low-alkali cleaning solution can be used.
[0059] After the high-alkali cleaning treatment and the low-alkali cleaning treatment, the stains attached to the surface of the silicon wafer and the damage layer on the surface of the silicon wafer are basically completely removed.
[0060] In some examples of this embodiment, after the low-alkali cleaning treatment, a step of washing the silicon wafer with water can be further included. The water washing can remove the residual alkali and hydrogen peroxide on the surface of the silicon wafer, and prepare for the subsequent cleaning and texturing treatment.
[0061] In step S3, the silicon wafer subjected to the low-alkali cleaning treatment is transferred to a texturing solution for a texturing treatment.
[0062] In some examples of this embodiment, the texturing solution can contain alkali and a texturing additive. The surface of the silicon wafer is subjected to anisotropic etching in the texturing solution, and a textured structure is formed. The specific selection and ratio of the alkali and the texturing additive can be performed in a manner known in the art, and will not be described here.
[0063] In some examples of this embodiment, after texturing, the process may include alkaline washing and acid washing of the silicon wafer. Alkaline washing repairs the surface structure of the silicon wafer, while acid washing removes the oxide layer generated during alkaline washing and also passivates the surface of the silicon wafer.
[0064] In some examples of this embodiment, after acid pickling, the silicon wafer can also be washed with water, slowly pulled up, and dried to obtain a silicon wafer with a textured surface and a clean surface for subsequent use.
[0065] Secondly, this application also proposes a silicon wafer cleaning and texturing apparatus.
[0066] Figure 2 This is a schematic diagram of the tank structure of the silicon wafer cleaning and texturing equipment. (Refer to...) Figure 2 As shown, the silicon wafer cleaning and texturing equipment includes a high-alkali cleaning tank 111, a low-alkali cleaning tank 112, and a texturing tank 120. The high-alkali cleaning tank 111 is used to contain high-alkali cleaning solution, the low-alkali cleaning tank 112 is used to contain low-alkali cleaning solution, and the texturing tank 120 is used to contain texturing solution. The high-alkali cleaning tank 111, the low-alkali cleaning tank 112, and the texturing tank 120 are sequentially arranged on the silicon wafer conveying path, and the low-alkali cleaning tank 112 is connected to the high-alkali cleaning tank 111.
[0067] It is understood that the high-alkali cleaning tank 111 is used to contain the high-alkali cleaning solution, the low-alkali cleaning tank 112 is used to contain the low-alkali cleaning solution, and the texturing tank 120 is used to contain the texturing solution. The high-alkali cleaning tank 111, the low-alkali cleaning tank 112, and the texturing tank 120 are sequentially arranged on the silicon wafer transport path.
[0068] Traditional technologies only perform one cleaning process before texturing, thus requiring only one cleaning tank. However, the silicon wafer cleaning and texturing equipment of this invention is designed based on the silicon wafer cleaning and texturing method. Corresponding to high-alkali and low-alkali cleaning processes, it includes a high-alkali cleaning tank 111, a low-alkali cleaning tank 112, and a low-alkali cleaning solution storage device. This saves on the amount of alkali raw materials used, thereby reducing the production cost of solar cells.
[0069] Figure 3 for Figure 2 A schematic diagram showing the connection structure between the low-alkali cleaning tank 112 and the high-alkali cleaning tank 111. (Refer to...) Figure 3As shown, in some examples of this embodiment, the silicon wafer cleaning and texturing device further comprises a low-alkali cleaning solution storage device connected to the high-alkali cleaning tank 111 and the low-alkali cleaning tank 112, and used for transferring the low-alkali cleaning solution in the low-alkali cleaning tank 112 to the high-alkali cleaning tank 111.
[0070] Referring to Figure 3 As shown, in some examples of this embodiment, the low-alkali cleaning solution storage device comprises a storage container 113 for receiving the low-alkali cleaning solution in the low-alkali cleaning tank 112, a discharge pipe 115 connected to the storage container 113 and the high-alkali cleaning tank 111, and a pump 114 for pumping the low-alkali cleaning solution.
[0071] Referring to Figure 2 As shown, in some examples of this embodiment, the silicon wafer cleaning device can further comprise a first water washing tank 210 arranged between the low-alkali cleaning tank 112 and the texturing tank 120.
[0072] Referring to Figure 2 As shown, in some examples of this embodiment, the silicon wafer cleaning device can further comprise, in sequence after the texturing tank 120, an alkali washing tank 130, an acid washing tank 140, a slow pulling tank 150, and a drying device 160. The alkali washing tank 130 can be used as a container for alkali washing of the silicon wafer, the acid washing tank 140 can be used as a container for acid washing of the silicon wafer, and the slow pulling tank 150 can be used as a container for slow pulling of the silicon wafer.
[0073] Referring to Figure 2 As shown, in some examples of this embodiment, the silicon wafer cleaning device can further comprise a second water washing tank 220 arranged between the texturing tank 120 and the alkali washing tank 130.
[0074] Referring to Figure 2 As shown, in some examples of this embodiment, the silicon wafer cleaning device can further comprise a third water washing tank 230 arranged between the alkali washing tank 130 and the acid washing tank 140.
[0075] Referring to Figure 2 As shown, in some examples of this embodiment, the silicon wafer cleaning device can further comprise a fourth water washing tank 240 arranged between the acid washing tank 140 and the slow pulling tank 150.
[0076] In a third aspect, the present disclosure further provides a textured silicon wafer obtained by the silicon wafer cleaning and texturing method described in the above embodiments.
[0077] In a fourth aspect, the present disclosure also provides a solar cell comprising the texturized silicon wafer in the above embodiments.
[0078] In order to make the present disclosure clearer, the following examples and comparative examples are provided.
[0079] Example 1
[0080] A high-alkaline cleaning solution was added into the high-alkaline cleaning tank, and the high-alkaline cleaning solution contained 0.27% of sodium hydroxide and 0.42% of hydrogen peroxide by mass concentration. A low-alkaline cleaning solution was added into the low-alkaline cleaning tank, and the low-alkaline cleaning solution contained 0.09% of sodium hydroxide and 0.42% of hydrogen peroxide by mass concentration. The volume of the high-alkaline cleaning solution and the low-alkaline cleaning solution was 370L.
[0081] The high-alkaline cleaning solution was heated to 65℃, and a batch of silicon wafers was immersed in the high-alkaline cleaning tank for 160s to perform high-alkaline cleaning treatment.
[0082] The low-alkaline cleaning solution was heated to 65℃, and the batch of silicon wafers was immersed in the low-alkaline cleaning tank for 160s to perform low-alkaline cleaning treatment.
[0083] The batch of silicon wafers was washed with deionized water to remove the residual cleaning solution on the surface of the silicon wafers.
[0084] The batch of silicon wafers was placed in a texturing agent to form a textured structure.
[0085] During the cleaning process, as the cleaning batch of silicon wafers increased, a certain amount of high-alkaline cleaning solution was discharged at a fixed time, and the low-alkaline cleaning solution was discharged into the high-alkaline cleaning tank to supplement the high-alkaline cleaning solution, and sodium hydroxide solution was added to the high-alkaline cleaning solution to supplement the alkali, so as to maintain the concentration of sodium hydroxide in the high-alkaline cleaning solution. Sodium hydroxide solution and hydrogen peroxide solution were supplemented into the low-alkaline cleaning solution to ensure the stability of the components of the low-alkaline cleaning solution.
[0086] Comparative Example 1
[0087] A cleaning solution was added into the cleaning tank, and the cleaning solution contained 0.27% of sodium hydroxide and 0.85% of hydrogen peroxide by mass concentration.
[0088] The cleaning solution was heated to 65℃, and a batch of silicon wafers was immersed in the high-alkaline cleaning tank for 180s to perform cleaning treatment.
[0089] The batch of silicon wafers was washed with deionized water to remove the residual cleaning solution on the surface of the silicon wafers.
[0090] The batch of silicon wafers was placed in a texturing agent to form a textured structure.
[0091] During the cleaning process, as the silicon wafer cleaning batch increases, a certain amount of cleaning solution is discharged at a fixed time, and the sodium hydroxide solution and the hydrogen peroxide solution are added correspondingly to maintain the concentration of the solutes in the high-alkali cleaning solution.
[0092] Comparative Example 2
[0093] Comparative Example 2 is basically the same as Example 1, the main difference is that the high-alkali cleaning solution with a mass concentration of 0.27% of sodium hydroxide and a mass concentration of 0.42% of hydrogen peroxide is also added to the low-alkali cleaning tank in Comparative Example 2. Accordingly, when the high-alkali cleaning solution is replenished, the low-alkali cleaning solution is discharged into the high-alkali cleaning tank to replenish the high-alkali cleaning solution, and there is no need to additionally add sodium hydroxide solution to the high-alkali cleaning tank to supplement the alkali.
[0094] Comparative Example 3
[0095] Comparative Example 3 is basically the same as Example 1, the main difference is that when the high-alkali cleaning solution is replenished, the corresponding sodium hydroxide solution and hydrogen peroxide solution are directly added for replenishment. When the low-alkali cleaning solution is replenished, the corresponding sodium hydroxide solution and hydrogen peroxide solution are also directly added for replenishment.
[0096] Test: The consumption of 41% sodium hydroxide solution and hydrogen peroxide solution required for cleaning 10,000 silicon wafers in Example 1 and Comparative Example 1 is counted. The results can be seen in Table 1.
[0097] Table 1
[0098]
[0099] Referring to Table 1, Example 1 uses the silicon wafer cleaning and texturing method provided by the present disclosure to clean the silicon wafer, and Comparative Example 1 uses the traditional one-time cleaning method. The alkali concentration in the high-alkali cleaning solution in Example 1 is equal to that in Comparative Example 1, and at the same time, the low-alkali cleaning solution is used as the replenishment of the high-alkali cleaning solution in Example 1, which is equivalent to that Example 1 only needs to supplement the consumption of the high-alkali cleaning solution, so Example 1 and Comparative Example 1 have the same consumption of sodium hydroxide solution. At the same time, the consumption of hydrogen peroxide solution in Comparative Example 1 reaches 6.63L, while the consumption of hydrogen peroxide solution in Example 1 is only 3.7L, which is mainly because the two-time silicon wafer cleaning and texturing method of Example 1 can effectively reduce the demand for hydrogen peroxide concentration of the cleaning solution, thereby effectively saving the amount of hydrogen peroxide.
[0100] Further, in the two cleaning tanks in Comparative Example 2, high-alkali cleaning solution is added, which can also reduce the consumption of hydrogen peroxide solution, but because a higher alkali concentration is used in the later cleaning tank in Comparative Example 2, more sodium hydroxide is consumed in the later cleaning step, and the consumption of sodium hydroxide solution is also increased accordingly. Further, in this cleaning method, because the alkali concentration in the later cleaning tank is also high, the weight loss of the silicon wafer during cleaning is also increased. In Comparative Example 3, low-alkali cleaning solution is not used to supplement the high-alkali cleaning solution, so although the hydrogen peroxide concentration in the two cleaning tanks is low, because the two cleaning tanks need to be supplemented at the same time, the consumption of sodium hydroxide solution is significantly increased.
[0101] Note that the above examples are for illustrative purposes only and are not meant to limit the present disclosure.
[0102] It should be understood that, unless specifically stated otherwise, the execution of steps is not strictly limited in sequence, and the steps can be executed in other sequences. Moreover, at least part of the steps in the preparation process can include multiple sub-steps or multiple stages, which do not necessarily have to be executed at the same time, but can be executed at different times, and the execution sequence of the sub-steps or stages is not necessarily sequential, but can be executed in rotation or alternation with other steps or at least part of the sub-steps or stages of other steps.
[0103] Each of the embodiments in the specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.
[0104] The technical features of the above embodiments can be combined in any manner, and to make the description concise, not all possible combinations of the technical features in the above embodiments are described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present disclosure.
Claims
1. A method for cleaning and texturing silicon wafers, characterized in that, The process includes the following steps: placing a silicon wafer in a high-alkali cleaning solution for high-alkali cleaning treatment, transferring the silicon wafer after the high-alkali cleaning treatment to a low-alkali cleaning solution for low-alkali cleaning treatment, and transferring the silicon wafer after the low-alkali cleaning treatment to a texturing solution for texturing treatment, wherein the mass concentration of alkali in the low-alkali cleaning solution is less than the mass concentration of alkali in the high-alkali cleaning solution. The silicon wafer cleaning and texturing method further includes: replenishing the high-alkali cleaning solution, wherein the replenishment process includes: adding the low-alkali cleaning solution as a replenishing solution to the high-alkali cleaning solution, and replenishing the high-alkali cleaning solution with alkali to maintain the mass concentration of alkali in the high-alkali cleaning solution.
2. The silicon wafer cleaning and texturing method according to claim 1, characterized in that, The mass concentration of alkali in the high-alkali cleaning solution is 0.19%~0.37%.
3. The silicon wafer cleaning and texturing method according to claim 2, characterized in that, The mass concentration of alkali in the low-alkali cleaning solution is 0.06%~0.12%.
4. The silicon wafer cleaning and texturing method according to any one of claims 1 to 3, characterized in that, Both the high-alkali cleaning solution and the low-alkali cleaning solution contain hydrogen peroxide as a solute. The mass concentration of hydrogen peroxide in the high-alkali cleaning solution is less than 0.5 wt%, and the mass concentration of hydrogen peroxide in the low-alkali cleaning solution is less than 0.5 wt%.
5. The silicon wafer cleaning and texturing method according to claim 4, characterized in that, The mass concentration of hydrogen peroxide in the high-alkalinity cleaning solution is 0.34%~0.5%; and / or, The mass concentration of hydrogen peroxide in the low-alkali cleaning solution is 0.34%~0.5%.
6. The silicon wafer cleaning and texturing method according to any one of claims 1 to 3 and 5, characterized in that, During the high-alkali cleaning process, the temperature of the high-alkali cleaning solution is controlled at 65℃~70℃, and the cleaning time is controlled at 150s~180s. And / or, During the low-alkali cleaning process, the temperature of the low-alkali cleaning solution is controlled at 65℃~70℃, and the cleaning time is controlled at 150s~180s.
7. A silicon wafer cleaning and texturing equipment, characterized in that, It includes a high-alkali cleaning tank, a low-alkali cleaning tank, and a texturing tank. The high-alkali cleaning tank is used to contain high-alkali cleaning solution, the low-alkali cleaning tank is used to contain low-alkali cleaning solution, and the texturing tank is used to contain texturing solution. The high-alkali cleaning tank, the low-alkali cleaning tank, and the texturing tank are sequentially arranged on the silicon wafer conveying path, and the low-alkali cleaning tank is connected to the high-alkali cleaning tank.
8. The silicon wafer cleaning and texturing equipment according to claim 7, characterized in that, It also includes a low-alkali cleaning solution storage device, which is connected to the high-alkali cleaning tank and the low-alkali cleaning tank. The low-alkali cleaning solution storage device is used to transfer the low-alkali cleaning solution in the low-alkali cleaning tank to the high-alkali cleaning tank.
9. The silicon wafer cleaning and texturing equipment according to claim 7, characterized in that, The low-alkali cleaning solution storage device includes a storage container, a drain pipe, and a pump. The storage container is used to receive the low-alkali cleaning solution in the low-alkali cleaning tank. The drain pipe is connected to the storage container and the high-alkali cleaning tank. The pump is used to pump the low-alkali cleaning solution into the high-alkali cleaning tank.
10. A texturized silicon wafer, characterized in that, The texturized silicon wafer is obtained by cleaning and texturing the silicon wafer as described in any one of claims 1 to 6.
11. A solar cell, characterized in that, The solar cell includes the texturized silicon wafer as described in claim 10.