Monocrystalline silicon texturing additive for improving heavy line marks of original silicon wafer as well as preparation method and application of monocrystalline silicon texturing additive

Abstract

The invention relates to a monocrystalline silicon texturing additive for improving heavy line marks of an original silicon wafer as well as a preparation method and application of the monocrystalline silicon texturing additive. The texturing additive comprises the following components in parts by weight: 1-3 parts of a nucleating agent; 0.1 to 1 part of a copolymer; 0.5 to 2 parts of a surfactant; 1-5 parts of a dispersing aid; 1-5 parts of an inorganic base; and 60-80 parts of deionized water. The nucleating agent with a complex structure and various biological activities is adopted, the special main chain and side chain structures of the nucleating agent endow the nucleating agent with unique biological activity and physicochemical characteristics, and components such as the copolymer are compounded for texturing, so that the defect area of the original silicon wafer with heavy line marks is repaired and etched, and meanwhile, the defect area of the original silicon wafer with heavy line marks is repaired. And when a small amount of texturing additive is used, the influence of multiple factors such as the repairing effect and the like is more emphasized.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor manufacturing processes, and particularly relates to a single-crystalline silicon texturing additive for improving heavy line marks on a raw silicon wafer, a preparation method thereof, and an application thereof. Background Art

[0002] During the manufacturing process of single-crystalline silicon solar cells, heavy line marks on the surface of the raw silicon wafer, such as saw marks, scratches, etc., have a significant negative impact on the texturing effect and the conversion efficiency of the battery. Texturing is a key process of forming a micro-nano scale textured surface structure on the silicon wafer through chemical etching, aiming to reduce light reflection and improve light absorption efficiency. However, the existence of heavy line marks will seriously interfere with this process.

[0003] First of all, heavy line marks will cause uneven distribution and penetration of the etching solution on the surface of the silicon wafer, resulting in inconsistent etching rates in the heavy line mark area and the normal area. This uneven etching will form an irregular textured surface structure, and some areas may be etched excessively while other areas are etched insufficiently, leading to poor uniformity of the surface morphology. This uneven textured surface structure will significantly increase the light reflectivity and reduce the light absorption efficiency of the silicon wafer, thereby directly affecting the short-circuit current (Isc) of the battery.

[0004] Secondly, the heavy line mark area is prone to becoming the center of carrier recombination. During the operation of the solar cell, photo-generated carriers need to migrate in the silicon wafer body and be collected by the electrodes, while the defects at the heavy line marks will capture carriers and increase the surface recombination rate. This will not only reduce the open-circuit voltage (Voc) of the battery, but also affect the fill factor (FF), ultimately resulting in a decrease in the overall conversion efficiency of the battery.

[0005] In addition, heavy line marks may also affect the uniformity of subsequent process steps. For example, deposition of the antireflection film and preparation of the electrodes. The uneven surface morphology will cause inconsistent coating thickness or poor electrode contact, further exacerbating the loss of battery performance.

[0006] In summary, the heavy line marks on the surface of the raw silicon wafer will not only destroy the uniformity of the texturing process, reduce the light absorption efficiency, but also increase carrier recombination and affect the electrical performance of the battery. Therefore, improving the heavy line mark problem is crucial for enhancing the texturing effect and the battery conversion efficiency, which is also an important driving force for developing efficient texturing additives and optimizing the cutting process. By reducing the influence of heavy line marks, the performance and reliability of single-crystalline silicon solar cells can be significantly improved, promoting the further development of photovoltaic technology. Summary of the Invention

[0007] The technical problem solved by the present invention: Aiming at the significant negative impact of heavy line marks on the raw silicon wafer, such as saw marks, scratches, etc., on the texturing effect and the battery conversion efficiency.

[0008] In view of the technical problems existing in the prior art, the present invention designs a single-crystal silicon texturing additive for improving the heavy wire marks of the original silicon wafer, its preparation method and application. By optimizing the chemical properties of the texturing solution, repairing surface defects and adjusting the etching rate, this additive forms a uniform textured surface structure in the area of heavy wire marks. After the original silicon wafer with heavy wire marks is prepared by it, the size and height of the textured pyramids are basically the same, and the distribution is uniform, and it has good light trapping properties and low reflectivity, and the conversion efficiency of the solar cell after preparation is similar to that of the normal silicon wafer.

[0009] It should be noted that in the present invention, unless otherwise specified, the specific meaning of "including" related to component limitations and descriptions includes both the open "including", "containing" and their similar meanings, and also includes the closed "consisting of" and their similar meanings.

[0010] In order to solve the above-mentioned existing technical problems, the present invention adopts the following solutions:

[0011] A single-crystal silicon texturing additive for improving the heavy wire marks of the original silicon wafer, characterized in that, calculated by weight, it includes the following components:

[0012]

[0013] 60 - 80 parts of deionized water;

[0014] The nucleating agent is one or more of lentinan, schizophyllan, pachyman, grifolan, and polysaccharide from coriolus versicolor.

[0015] Further, the copolymer is one or more of methoxypolyethylene glycol polylactic acid-glycolic acid copolymer (PLGA-mPEG), polystyrene-poly(4-vinylpyridine)-poly(ethylene oxide) (PS-PVP-PEO), polylactic acid-glycolic acid copolymer polyethylene glycol maleimide (PLGA-PEG-Mal), and polylactic acid-glycolic acid copolymer polyethylene glycol folic acid (PLGA-PEG-FA / Folate).

[0016] Further, the surfactant is one or more of allyloxy phenol ether sulfonate, alkyl diphenyl ether disulfonate, secondary alcohol polyoxyethylene ether, acrylamide methyl propane sulfonate, and isopropyl benzene sulfonate.

[0017] Further, the dispersion aid is one or more of hydroxyethyl methyl cellulose, hydroxyethyl ethylenediamine triacetic acid, hydroxyethyl ethylenediamine, triethylhexyl phosphate, and disodium ethylenediaminetetraacetate.

[0018] Further, the inorganic base is NaOH and / or KOH.

[0019] In the present invention, in order to further optimize the functions of the additives, each component thereof can be preferably selected as follows: nucleating agent 1 - 1.5 parts; copolymer 0.2 - 0.5 parts; surfactant 0.5 - 1 part; dispersion aid 1.5 - 2.5 parts; inorganic base 1 - 3 parts; deionized water 70 - 80 parts.

[0020] In the present invention, the nucleating agent is preferably Schizophyllan.

[0021] In the present invention, the copolymer is preferably methoxypolyethylene glycol poly(lactic - glycolic acid) copolymer.

[0022] In the present invention, the surfactant is preferably allyloxyphenol ether sulfonate.

[0023] In the present invention, the dispersion aid is preferably hydroxyethyl methyl cellulose.

[0024] In the present invention, the inorganic base is preferably NaOH.

[0025] The single - crystal silicon texturing additive for improving the heavy line marks of the original silicon wafer in the present invention has unique effects:

[0026] The single - crystal silicon texturing additive does not contain low - boiling - point components. The low - boiling - point components refer to components with boiling points lower than the temperature required for the texturing reaction, which is 82°C - 85°C. If the boiling point of a component is lower than 82°C, during the texturing reaction, the component will vaporize and pollute the environment.

[0027] The present invention also discloses a preparation method of a single - crystal silicon texturing additive for improving the heavy line marks of the original silicon wafer, which is characterized by including the following steps:

[0028] Weigh the corresponding amounts of inorganic base, nucleating agent, copolymer, surfactant and dispersion aid, add them to deionized water, and stir well at room temperature (20 - 25°C) for 2 - 3 hours until all components are mixed evenly, thus obtaining the single - crystal silicon texturing additive for improving the heavy line marks of the original silicon wafer.

[0029] The present invention also discloses the use of a single - crystal silicon texturing additive for improving the heavy line marks of the original silicon wafer prepared by the above - mentioned preparation method in the field of etching and texturing of single - crystal original silicon wafers with heavy line marks.

[0030] The present invention also discloses a texturing solution, which includes the above - mentioned single - crystal silicon texturing additive for improving the heavy line marks of the original silicon wafer, inorganic base and deionized water.

[0031] The mass ratio of the single - crystal silicon texturing additive for improving the heavy line marks of the original silicon wafer, inorganic base and deionized water is 0.3 - 0.6:0.4 - 0.8:100.

[0032] The inorganic base is NaOH and / or KOH.

[0033] In the present invention, the mass ratio of the single-crystal silicon texturing additive, inorganic base, and deionized water for improving the heavy line marks on the original silicon wafer is preferably 0.4:0.5:100.

[0034] The present invention also discloses a preparation method of the above-mentioned texturing solution, which is characterized by comprising the following steps:

[0035] Weigh the single-crystal silicon texturing additive and inorganic base for improving the heavy line marks on the original silicon wafer, add them to deionized water at 82 - 83 °C, and stir for 1 - 2 min until evenly mixed to obtain the single-crystal silicon etching texturing solution.

[0036] The present invention also discloses a usage method of the above-mentioned texturing solution, which is characterized by comprising the following steps:

[0037] Heat the above-mentioned texturing solution to the reaction temperature of 82 - 83 °C, put the heavy line mark single-crystal original silicon wafer into the above-mentioned texturing solution for texturing reaction, with the texturing time of 430 - 450 s, take out the heavy line mark single-crystal silicon wafer, rinse the front and back sides of the heavy line mark single-crystal silicon wafer with deionized water and absolute ethanol respectively, and dry the surface of the heavy line mark single-crystal silicon wafer under the protection of N2.

[0038] In the usage method of the texturing solution of the present invention, the texturing temperature can preferably be 83 °C, the texturing time can preferably be 440 - 450 s, more preferably 450 s, the time for rinsing the taken-out heavy line mark single-crystal silicon wafer with deionized water and absolute ethanol respectively is 20 - 60 s, preferably 20 - 45 s, more preferably 25 s. The N2 drying time is 200 - 300 s, preferably 240 - 270 s, more preferably 240 s.

[0039] The present invention provides a single-crystal silicon texturing additive for improving the heavy line marks on the original silicon wafer, its preparation method and application. By using a nucleating agent with a complex structure and diverse biological activities, the nucleating agent is preferably Schizophyllan. Its special main chain and side chain structures endow Schizophyllan with unique biological activities and physicochemical properties. It cooperates with a copolymer with good hydrophilicity, and is compounded with components such as surfactants and dispersion aids for texturing, having the following beneficial effects:

[0040] 1. The preferred Schizophyllan as the nucleating agent in the present invention is composed of β-(1,3)-D-glucose units, forming a linear main chain. On some glucose units of the main chain, single glucose units are connected through β-(1,6)-glycosidic bonds to form a branched structure. In an alkaline environment, under the action of a dispersion aid, it can react rapidly with the heavy line marks (such as saw marks, scratches, etc.), that is, the mechanical damage layer on the surface of the original silicon wafer. The D-glucose structure reacts first from the damage layer, especially from the line marks, microcracks, and defects, that is, as the nucleation starting point, to selectively repair the heavy line mark area.

[0041] 2. The present invention uses a copolymer and a nucleating agent in combination. The special structure composed of the hydrophilic methoxypolyethylene glycol (mPEG) and the hydrophobic poly (lactic-co-glycolic acid) (PLGA) in the amphiphilic block copolymer has good biocompatibility. While its hydrophilic part provides good water solubility, it promotes the rapid reaction of the nucleating agent with the deep damaged lines of the original silicon wafer, preferentially etches, and ensures the preferential texturing repair of the damaged area. Its hydrophobic part forms micelles or nanoparticles in water, fills the heavy lines, and promotes the uniformity of local corrosion. The nucleating agent in the texturing additive and the copolymer act synergistically to preferentially corrode the heavy line area, fill and repair defects, and ensure that the corrosion rate of the non-defective area is lower than that of the heavy line area, thereby realizing the planarization of the pyramidal structure on the surface of the silicon wafer after texturing.

[0042] 3. The surfactant used in the present invention is preferably allyloxy phenol ether sulfonate. Its addition endows each component with better water solubility, enables them to be uniformly dispersed in the aqueous texturing solution, reduces the surface tension, improves the wettability and permeability of the texturing solution, makes the texturing process more uniform, and better assists in preferentially repairing defects and etching reactions in the heavy line area.

[0043] 4. The monocrystalline silicon texturing additive and the texturing solution of the present invention use environmentally friendly components, which better reduce environmental pollution. Moreover, each component cooperates with each other, making the raw material price of the texturing solution low, and suitable for large-scale industrial production. Description of the Drawings

[0044] Figure 1 : It is a 1000-fold magnified dark-field optical microscope picture of the textured surface of the silicon wafer obtained by texturing the original silicon wafer with heavy lines using the texturing solution of Example 1 of the present invention;

[0045] Figure 2 : It is a 3D textured surface picture of the Zeta-20 pyramid of the silicon wafer obtained by texturing the original silicon wafer with heavy lines using the texturing solution of Example 1 of the present invention;

[0046] Figure 3 : It is a 1000-fold magnified dark-field optical microscope picture of the textured surface of the silicon wafer obtained by texturing the original silicon wafer with heavy lines using the texturing solution of Comparative Example 1 of the present invention;

[0047] Figure 4 : It is a 3D textured surface picture of the Zeta-20 pyramid of the silicon wafer obtained by texturing the original silicon wafer with heavy lines using the texturing solution of Comparative Example 1 of the present invention. Detailed Embodiments

[0048] The following further describes the present invention in conjunction with specific embodiments and the accompanying drawings:

[0049] Examples 1-7 and Comparative Examples 1-5 disclose a variety of monocrystalline silicon texturing additives for improving the heavy lines of the original silicon wafer, and the components and mass ratios thereof are shown in Table 1.

[0050] The preparation method of the single-crystal silicon texturing additive for improving the heavy wire marks on the original silicon wafer is as follows:

[0051] Weigh the corresponding amounts of inorganic base, nucleating agent, copolymer, surfactant and dispersion aid in sequence and add them to deionized water. Stir continuously and sufficiently for 3 hours at room temperature of 25 °C until all components are evenly mixed, thus obtaining the single-crystal silicon texturing additive required for improving the heavy wire marks on the original silicon wafer.

[0052] Table 1 Examples 1 - 7

[0053]

[0054]

[0055] Table 2 Comparative Examples 1 - 5

[0056]

[0057]

[0058] Regarding the preparation method of the texturing solution of the present invention:

[0059] Weigh the above-prepared single-crystal silicon texturing additive for improving the heavy wire marks on the original silicon wafer, NaOH and deionized water respectively, and weigh them according to the mass ratio of 0.4:0.5:100. Add the texturing additive and NaOH to the deionized water at 83 °C and stir for 2 min until evenly mixed, thus preparing the single-crystal silicon etching texturing solution.

[0060] Regarding the usage method of the texturing solution:

[0061] Put the single-crystal silicon wafer with heavy wire marks into the texturing solution for texturing reaction. The texturing temperature is 83 °C and the texturing time is 450 s. After the reaction, take out the single-crystal silicon wafer with heavy wire marks and rinse the front and back sides of the wafer with deionized water and absolute ethanol for 25 s respectively, and dry it with N2 for 240 s.

[0062] Regarding performance testing and description:

[0063] Performance 1 Test method for silicon wafer weight loss performance:

[0064] Use an analytical balance with a scale division value of 0.001 g to weigh the single-crystal silicon wafer before and after texturing respectively, and record them as W 前 and W 后 , then the calculation method of the weight loss η is: η = W 前 -W 后 , and the test results are shown in Table 3.

[0065] Performance 2 Test method for reflectivity:

[0066] Measure the absolute reflectivity using a film thickness gauge, and then perform integral processing on the obtained data to obtain the weighted average reflectivity. The test results are shown in Table 3.

[0067] Performance 3 Test methods for tower base size, tower base height, surface density of velvet, and specific surface area:

[0068] For data such as the tower base size, tower base height, surface density of velvet, and specific surface area of the silicon wafer with velvet surface after texturing, the average value is obtained by measuring the results of 10 cross-sections simultaneously using a Zeta-20 microscope. The test results are shown in Table 3.

[0069] Performance 4 Test method for velvet surface:

[0070] The silicon wafers before and after texturing are tested using an optical microscope and a Zeta-20 microscope respectively to observe the velvet surface conditions. The test results are shown in Figures 1-4 .

[0071] Table 3 Test data of Examples 1-7 and Comparative Examples 1-5

[0072]

[0073] Analysis and explanation regarding the test results:

[0074] It can be seen from the test data in Table 3 that for the silicon wafers with heavy wire marks that have undergone the same cutting treatment, the velvet surface of the silicon wafers obtained by using the texturing solution prepared with the single-crystalline silicon texturing additive of Example 1 for improving the heavy wire marks of the original silicon wafers (see Figure 1 and Figure 2 ) is more uniform in the distribution of velvet pyramids, more uniform in tower base size, higher in surface density of velvet, and has better repair and texturing effects in the wire mark area than the velvet surface of the silicon wafers obtained by using the texturing solution prepared with the texturing additive of Comparative Example 1 for the same silicon wafers with heavy wire marks (see Figure 3 and Figure 4 ).

[0075] In summary, under the same texturing conditions and the same mass ratio of the texturing solution, for texturing, in terms of velvet surface morphology, repair of the wire mark area, tower base size, height, and surface density of velvet, the texturing effect of the examples of the present invention on the original silicon wafers with heavy wire marks is significantly better than that of the comparative examples.

[0076] Further comparative illustration is made through the accompanying drawings of the specification:

[0077] Figure 1 is a dark-field optical microscope image of the velvet surface of the silicon wafer obtained after texturing the original silicon wafer with heavy wire marks using the texturing solution of Example 1 of the present invention, magnified 1000 times; it can be seen from Figure 1 that the velvet surface of the silicon wafer with heavy wire marks after texturing with the texturing solution of Example 1 is uniformly repaired and of the same size, and the repair effect in the heavy wire mark area is obvious. After texturing, it is indistinguishable from the velvet surface of a normal silicon wafer, and no obvious wire marks are seen.

[0078] Figure 2 This is a 3D picture of the Zeta-20 pyramid texture on the silicon wafer obtained after texturing the heavy line mark original silicon wafer with the texturing solution of Example 1 of the present invention; it can be seen from Figure 2 that for the textured surface of the heavy line mark silicon wafer using the texturing solution of Example 1, the base size and height of the pyramid on the textured surface tend to be at the same level, with uniform distribution and no obvious pyramid missing area.

[0079] Figure 3 This is a picture of the dark field optical microscope of the textured surface of the silicon wafer obtained after texturing the heavy line mark original silicon wafer with the texturing solution of Comparative Example 1 of the present invention, magnified 1000 times; it can be seen from Figure 3 that for the textured surface of the heavy line mark silicon wafer using the texturing solution of Comparative Example 1, the fluffing effect in the heavy line mark area is poor, and there are obvious missing and non-fluffing phenomena of the pyramids on the textured surface.

[0080] Figure 4 This is a 3D picture of the Zeta-20 pyramid texture on the silicon wafer obtained after texturing the heavy line mark original silicon wafer with the texturing solution of Comparative Example 1 of the present invention; it can be seen from Figure 4 that for the textured surface of the heavy line mark silicon wafer using the texturing solution of Comparative Example 1, the base size and height of the pyramid on the textured surface are different and unevenly distributed, and there are obvious differences between the line mark area and the normal area after texturing.

[0081] The present invention preferably uses schizophyllan as a nucleating agent. Based on its special structure of β-(1,3)-D-glucose main chain and β-(1,6)-glycosidic bond side chain, it preferentially adsorbs on damaged areas such as heavy line marks and microcracks, and serves as a nucleation starting point to initiate the etching reaction directionally. It cooperates with block copolymers to synergistically enhance the effect. Combining allyloxy phenol ether sulfonate can improve the reaction activity through the allyl double bond, the phenol ether structure enhances stability, and the sulfonic acid group strengthens the hydrophilic dispersibility. The three cooperate to reduce the surface tension of the texturing solution, stabilize the particle distribution in the system, enhance the wetting and permeability, and achieve selective repair of the damaged area and uniform texturing. At the same time, the whole system uses biodegradable components to reduce pollution; the formulation components have strong synergistic effect and low dosage, taking into account high-efficiency repair and cost control, and are suitable for large-scale production.

[0082] The texturing additive of the present invention makes the corrosion rate of the non-defective area lower than that of the heavy line mark area through preferential nucleation etching in the damaged area. In the same time, it ensures that the normal area is not over-etched, the defect area has a faster rate and more etching, significantly improving the repair efficiency of the heavy line marks. After texturing, the uniformity and light absorption ability of the textured surface of the silicon wafer are enhanced, the battery conversion efficiency is improved, and at the same time, the goal of a green process is achieved.

[0083] The present invention has been described by way of examples in combination with the embodiments and the drawings. Obviously, the implementation of the present invention is not limited by the above-mentioned manner. As long as various improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A single crystal silicon texturing additive for improving the heavy line marks of original silicon wafers, characterized in that: Calculated by weight, it includes the following components: The nucleating agent is one or more of Lentinan, Schizophyllan, Poria cocos polysaccharide, Grifola frondosa polysaccharide and Coriolus versicolor polysaccharide.

2. The single crystal silicon texturing additive for improving the heavy line marks of original silicon wafers according to claim 1, characterized in that: The copolymer is one or more of methoxy polyethylene glycol polylactic acid-glycolic acid copolymer, polystyrene-polytetravinylpyridine-polyethylene oxide, polylactic acid-glycolic acid copolymer polyethylene glycol maleimide, and polylactic acid-glycolic acid copolymer polyethylene glycol folic acid.

3. The single crystal silicon texturing additive for improving the heavy line marks of original silicon wafers according to claim 1, characterized in that: The surfactant is one or more of allyloxyphenol ether sulfonate, alkyl diphenyl ether disulfonate, secondary alcohol polyoxyethylene ether, acrylamide methyl propane sulfonate, and isopropylbenzene sulfonate.

4. The single crystal silicon texturing additive for improving the heavy line marks of original silicon wafers according to claim 1, characterized in that: The dispersing aid is one or more of hydroxyethyl methyl cellulose, hydroxyethyl ethylenediamine triacetic acid, hydroxyethyl ethylenediamine, triethylhexyl phosphate, and disodium ethylenediaminetetraacetate.

5. A method for preparing a single crystal silicon texturing additive for improving heavy line marks of original silicon wafers according to any one of claims 1 to 4, characterized in that: The following steps are involved: Weigh corresponding amounts of inorganic base, nucleating agent, copolymer, surfactant and dispersing aid, add into deionized water, stir thoroughly for 2-3 hours at room temperature until all components are evenly mixed, and obtain the single crystal silicon texturing additive for improving the heavy line marks of original silicon wafers.

6. Use of the single crystal silicon texturing additive for improving heavy line marks of original silicon wafers as described in any one of claims 1 to 4 in the field of etching and texturing of heavy line marks of single crystal original silicon wafers.

7. A texturing liquid, characterized in that: The invention comprises the single crystal silicon texturing additive for improving the heavy line marks of the original silicon wafer as described in any one of claims 1 to 4, an inorganic base and deionized water.

8. The texturing liquid according to claim 7, characterized in that: The mass ratio of the monocrystalline silicon texturing additive, inorganic alkali and deionized water used to improve the heavy line marks of the original silicon wafer is 0.3-0.6:0.4-0.8:

100.

9. A method for preparing the texturing liquid according to claim 7 or 8, characterized in that: The following steps are involved: Weigh the single crystal silicon texturing additive and inorganic alkali used to improve the heavy line marks of the original silicon wafer, add them into deionized water at 82-83° C. and stir for 1-2 minutes until the mixture is evenly mixed, so as to obtain the single crystal silicon etching texturing solution.

10. A method for using the texturing liquid according to claim 7 or 8, characterized in that: The following steps are involved: Heat the above-mentioned texturing liquid to the reaction temperature of 82-83°C, put the heavy line mark single crystal original silicon wafer into the above-mentioned texturing liquid for texturing reaction, the texturing time is 430-450s, take out the heavy line mark single crystal silicon wafer, rinse the front and back sides of the heavy line mark single crystal silicon wafer with deionized water and anhydrous ethanol respectively, and blow dry the surface of the heavy line mark single crystal silicon wafer under N2 protection conditions.

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