Cleaning method to reduce acid spots on silicon materials

Abstract

The present invention discloses a cleaning method for reducing silicon material acid spots, including: pickling, pickling silicon material, the acid solution used for pickling includes hydrofluoric acid, nitric acid and water in a mass ratio of 1: (18-20): (9-10), the pickling temperature is 20 ℃-24 ℃, and the pickling time is 40s-200s; warm water rinsing, using 25 ℃-80 ℃ warm water to carry out warm water rinsing on the silicon material after pickling, and then drying. In this application, by optimizing the pickling solution composition, controlling the pickling temperature, forming a complex on the silicon material surface, promoting the complex to separate from the silicon material during warm water rinsing, it is beneficial to reduce acid consumption and reduce the unit volume pickling solution cost; After cleaning, the silicon material surface is glossy and no acid spots are produced, the oxide layer is cleaned once and the yield rate is improved, the oxide layer removal efficiency is improved, and the silicon material surface quality is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a cleaning method for reducing acid spots on silicon materials. Background Art

[0002] Currently, a mixture of hydrofluoric acid and nitric acid is usually used to chemically react with pollutants to clean the pollutants on the surface of silicon materials. The chemical reaction equation includes:

[0003] SiO2+6HF=H2SiF6+2H2O;

[0004] Si+4HNO3+18HF=3H2SiF6+4NO+8H2O;

[0005] In the pickling process, the volume ratio of hydrofluoric acid (electron, concentration 49%) and nitric acid (electron, concentration 69%) in the mixed acid is 1:7-9. The initial reaction time is long, the volume is relatively small, and the temperature is high. Under the current equipment status, in the initial stage of mixed acid configuration, the silicon material will react rapidly and violently with the mixed acid, and at the same time, all kinds of oxides attached to the surface will be completely removed. After the process is completed, the silicon material needs to be taken out. The moment the silicon material is taken out of the acid tank, acid spots are easily generated on the surface, causing new oxide impurities to form on the surface. Therefore, each time the mixed acid is configured, a large amount of unqualified materials will need to be reworked. The rework will result in a low cleaning pass rate, and the rework will increase production. Cost and manufacturing cost, thus the cost of raw materials (silicon material loss) and auxiliary materials (water, electricity, compressed air, auxiliary tooling loss) also increase accordingly; at the same time, the surface quality of silicon materials is usually inspected manually, which is highly dependent on personnel. If they are not strictly selected and flow into the next process for crushing and then enter the crystal pulling end, it will affect the quality of the crystal rod, reduce the minority carrier lifetime, increase the oxygen content, and affect the yield and crystal yield; in the process of rework and transmission, the mutual friction between silicon materials and the contact with equipment may cause tiny damage and dust generation, resulting in certain losses. Repeated cleaning reaction and drying process, if the drying temperature of fine powder is too high or the drying time is too long, it may also cause a small amount of silicon material to be lost by sublimation or pyrolysis.

[0006] Therefore, a silicon material pickling method that can reduce acid spots and improve the cleaning pass rate is particularly necessary. Summary of the Invention

[0007] The object of the present invention is to provide a cleaning method for reducing acid spots on silicon materials.

[0008] The present invention is achieved in that:

[0009] In a first aspect, the present invention provides a cleaning method for reducing acid spots on silicon materials, comprising:

[0010] Pickling: Pickling the silicon material. The acid solution used for pickling includes hydrofluoric acid, nitric acid and water in a mass ratio of 1: (18-20): (9-10). The pickling temperature is 20° C.-30° C. and the pickling time is 40s-200s.

[0011] Rinse with warm water: Use warm water at 25℃-80℃ to rinse the acid-washed silicon material with warm water, and then dry it.

[0012] In an optional embodiment, when the mass volume ratio of the pickled silicon material to the acid solution is 33 kg / L-35 kg / L, a hydrofluoric acid solution is added to the acid solution, and the mass fraction of hydrofluoric acid in the hydrofluoric acid solution is 45%-50%.

[0013] In an optional embodiment, the ratio of the volume of the added hydrofluoric acid solution to the volume of the acid solution is 0.33-0.35.

[0014] In an optional embodiment, when the mass volume ratio of the silicon material after pickling to the acid solution reaches 33kg / L-35kg / L, a mixed acid is added to the acid solution, wherein the mixed acid includes hydrofluoric acid, nitric acid and water in a mass ratio of 1:(5-6):(3-4).

[0015] In an optional embodiment, 0.9 ml to 1.1 ml of mixed acid is added for every 0.3 kg of silicon material acid-washed.

[0016] In an optional embodiment, the time the silicon material is exposed to air between acid washing and warm water rinsing is less than 1 minute.

[0017] In an optional embodiment, the pickling is carried out in a pickling tank, which is provided with a circulating liquid inlet and a circulating liquid outlet, a circulating pipe is connected between the circulating liquid inlet and the circulating liquid outlet, and a cooling water machine is provided on the circulating pipe, which cools the liquid passing through it to 14°C-18°C.

[0018] In an optional embodiment, after the warm water rinsing, the silicon material is further subjected to pure water rinsing, selective treatment and drying in sequence, and the selective treatment includes at least one of bubbling rinsing, wind shear drying and high-temperature drainage.

[0019] In an alternative embodiment, the temperature of the drying step is 70° C.-85° C. and the pressure is less than 80 MPa.

[0020] In an optional embodiment, the method further includes monitoring the thinning amount of the silicon material after drying relative to the silicon material before pickling:

[0021] If the thinning amount is less than 5μm and the silicon material surface is white or atomized, add nitric acid to the acid solution;

[0022] If the thinning amount is less than 5μm and the cut surface of the silicon material has non-silicon substances attached, is dark, or has obvious diamond wire marks, add hydrofluoric acid to the acid solution;

[0023] If the thinning amount is greater than 10μm and there are acid spots on the surface of the silicon material, reduce the concentration of hydrofluoric acid in the acid solution.

[0024] The present invention has the following beneficial effects:

[0025] In the present application, by optimizing the composition of the pickling solution and controlling the pickling temperature, a complex is formed on the surface of the silicon material, and the complex is caused to separate from the silicon material during warm water rinsing, which is beneficial to reducing acid consumption and lowering the cost of the pickling solution per unit volume; after cleaning, the surface of the silicon material is glossy and no acid spots are produced, the yield of the oxide layer is improved after one cleaning, the efficiency of oxide layer removal is improved, and the surface quality of the silicon material is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a photo of the white surface of the silicon material in Example 1;

[0028] Figure 2 This is a photo of non-silicon matter attached to the cut surface of the silicon material in Example 1 (the surface appears to be oily);

[0029] Figure 3 This is a photo of acid spots on the surface of the silicon material in Example 1;

[0030] Figure 4 This is a photo of the silicon material after cleaning in Example 1;

[0031] Figure 5 This is a photo of the silicon material after cleaning in Comparative Example 1;

[0032] Figure 6 The temperature in the pickling tank in the early stage of pickling in Example 1 and Comparative Example 1 changes with the amount of silicon material cleaned. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0034] An embodiment of the present invention provides a cleaning method for reducing acid spots on silicon materials, comprising:

[0035] Pickling: Pickling the silicon material. The acid solution used for pickling includes hydrofluoric acid, nitric acid and water in a mass ratio of 1: (18-20): (9-10). The pickling temperature is 20° C.-30° C. and the pickling time is 40s-200s.

[0036] Rinse with warm water: Use warm water at 25℃-80℃ to rinse the acid-washed silicon material with warm water, and then dry it.

[0037] In the early stage of pickling, a chemical reaction Si+4HNO3+18HF=3H2SiF6+4NO+8H2O occurs. This chemical reaction is relatively violent, and the pickling temperature rises sharply. The high temperature further intensifies the intensity of the reaction, which reduces the controllability of pickling. At the same time, a large amount of nitrogen oxides are generated, which also causes acid spots on the surface of the silicon material. In this application, in order to reduce acid spots, the concentration of hydrofluoric acid in the pickling solution is first reduced, and the pickling temperature is controlled to ensure that the pickling temperature is between 20°C and 24°C, reducing the reduction in pickling controllability caused by the temperature rise, which in turn leads to the generation of acid spots.

[0038] Specifically, in the embodiment of the present application, the acid solution used for pickling includes hydrofluoric acid, nitric acid and water in a mass ratio of 1: (16-18): (10-13), wherein the acid solution can be prepared by mixing hydrofluoric acid (electron pole, concentration 49%) and nitric acid (electron pole, concentration 69%) in a mass ratio. After the pickling step, the pickled silicon material is rinsed with warm water. As the rinsing water temperature increases, the residue on the surface of the silicon material can be dissolved and detached faster, which is beneficial to improving the cleaning efficiency, reducing the formation of acid spots, and thus helping to improve the pickling pass rate.

[0039] The water used for warm water rinsing can come from the water generated by subsequent drying, wind shearing, and high-temperature drainage. In some embodiments, the water temperature used for warm water rinsing is about 30°C-50°C, which is more conducive to ensuring the cleaning effect of the silicon material; in some embodiments, the rinsing time can be 630s-1080s.

[0040] In some embodiments, in order to ensure sufficient contact between the solid and the liquid during pickling or rinsing, a bubbling device can be introduced to fully stir the liquid.

[0041] In an optional embodiment, when the mass volume ratio of the pickled silicon material to the acid solution is 33 kg / L-35 kg / L, a hydrofluoric acid solution is added to the acid solution, and the mass fraction of hydrofluoric acid in the hydrofluoric acid solution is greater than 45%.

[0042] As the pickling of silicon material proceeds, the hydrofluoric acid in the pickling solution is continuously consumed. To ensure the pickling effect, it is necessary to add hydrofluoric acid. The added hydrofluoric acid should have a higher concentration. In some embodiments, an electron-polarized, 49% hydrofluoric acid can be added.

[0043] In an optional embodiment, the ratio of the volume of the added hydrofluoric acid solution to the volume of the acid solution is 0.33-0.35.

[0044] If the volume of hydrofluoric acid solution added is too much, the risk of acid spots may still increase. However, if the volume of hydrofluoric acid solution added is too low, the silicon material cannot be cleaned completely. Therefore, the volume of hydrofluoric acid solution added needs to be appropriate.

[0045] In an optional embodiment, when the mass volume ratio of the silicon material after pickling to the acid solution reaches 33kg / L-35kg / L, a mixed acid is added to the acid solution, wherein the mixed acid includes hydrofluoric acid, nitric acid and water in a mass ratio of 1:(5-6):(3-4).

[0046] As the pickling of silicon materials proceeds, the hydrofluoric acid and nitric acid in the pickling solution will be continuously consumed, so hydrofluoric acid and nitric acid need to be added. At this time, since the solution in the pickling tank can dilute the mixed acid, in order to ensure the effect of silicon material pickling, the concentration of hydrofluoric acid in the mixed acid can be slightly increased compared to the initial concentration of the pickling solution.

[0047] In an optional embodiment, 0.9 ml to 1.1 ml of mixed acid is added for every 0.3 kg of silicon material acid-washed.

[0048] In an optional embodiment, the time the silicon material is exposed to air between acid washing and warm water rinsing is less than 1 minute.

[0049] Increasing the exposure time of silicon materials in the air will increase the time for acid spot formation reaction, thereby reducing the pickling pass rate.

[0050] In an optional embodiment, the pickling is carried out in a pickling tank, which is provided with a circulating liquid inlet and a circulating liquid outlet, a circulating pipe is connected between the circulating liquid inlet and the circulating liquid outlet, and a cooling water machine is provided on the circulating pipe, which cools the liquid passing through it to 14°C-18°C.

[0051] A cooling water machine is used to cool the pickling liquid to control the temperature of the pickling liquid in the pickling tank to be stable between 20℃ and 24℃, which is beneficial to improving the controllability of the pickling step.

[0052] In an optional embodiment, after the warm water rinsing, the silicon material is further subjected to pure water rinsing, selective treatment and drying in sequence, and the selective treatment includes at least one of bubbling rinsing, wind shear drying and high-temperature drainage.

[0053] After the warm water rinse, the silicon material can be transferred to a pure water rinse tank for further pure water rinsing. Alternatively, it can proceed directly to the wind shear drying or high-temperature draining step for preliminary drying before being transferred to the drying step. Wind shear drying can utilize a blower to increase the air velocity over the silicon material surface to accelerate its drying rate. In some embodiments, the temperature can be appropriately increased to further increase the drying rate. During the high-temperature draining step, the temperature can be set at approximately 85°C.

[0054] It should be noted that, in the method of the present application, except for the water derived from nitric acid or hydrofluoric acid, all other water is pure water with a resistivity greater than 15 megohms.

[0055] In an optional embodiment, the temperature of the drying step is 70° C.-85° C., the pressure is less than 80 MPa, and vacuum drying is beneficial to increase the drying rate.

[0056] In an optional embodiment, the method further includes monitoring the thinning amount of the silicon material after drying relative to the silicon material before pickling:

[0057] If the thinning amount is less than 5μm and the silicon material surface is visually white or atomized, add nitric acid to the acid solution;

[0058] If the thinning amount is less than 5μm and the cut surface of the silicon material is dark or the diamond wire marks are obvious, add hydrofluoric acid to the acid solution;

[0059] If the thinning amount is greater than 10μm and there are acid spots on the surface of the silicon material, reduce the concentration of hydrofluoric acid in the acid solution.

[0060] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0061] Example 1

[0062] This embodiment provides a cleaning method for reducing acid spots on silicon materials, comprising:

[0063] Acid pickling: transfer the single crystal silicon recycled material to the pickling tank for pickling. The pickling time is 60s. 41L hydrofluoric acid (electronic pole, mass fraction 49%) and 550L nitric acid (electronic pole, mass fraction 69%) are added to the pickling tank. The initial temperature of the pickling liquid is 22°C. The pickling tank is provided with a circulating liquid inlet and a circulating liquid outlet. A circulating pipe is connected between the circulating liquid inlet and the circulating liquid outlet. A cooling water machine is provided on the circulating pipe. The cooling water machine cools the liquid passing through it to 14°C-18°C.

[0064] After warm water rinsing and pickling, the silicon material is taken out of the pickling tank and transferred to the warm water rinsing tank. During this period, the silicon material is exposed to the air for 30 seconds. The pickled silicon material is rinsed with warm water at 40℃-45℃, rinsed with pure water, drained at high temperature and dried. The temperature of the drying step is 80℃ and the pressure is 80MPa.

[0065] Among them, the silicon material is added to the pickling tank according to about 150 kg per batch. After the pickling of 20 tons of silicon material is completed, 20L of electron electrode and 49% mass fraction of hydrofluoric acid are added to the pickling tank. At the same time, 300 mL of hydrofluoric acid (electron electrode, mass fraction 49%) and 1200 mL of nitric acid (electron electrode, mass fraction 69%) are added to the pickling tank every time 3 batches of silicon material are pickled;

[0066] It also includes monitoring the thinning amount of the silicon material after drying relative to the silicon material before pickling:

[0067] If the thinning amount is less than 5μm and the silicon material surface is visually white or atomized, Figure 1 As shown, nitric acid is gradually added to the acid solution until the surface of the silicon material turns white or the atomization disappears;

[0068] If the thinning amount is less than 5μm and the cut surface of the silicon material is visually adhered to non-silicon matter, darkened or with obvious diamond wire marks, such as Figure 2 As shown, gradually add hydrofluoric acid to the acid solution until the cut surface of the silicon material is no longer dark or the diamond wire marks are not obvious;

[0069] If the thinning amount is greater than 10μm and there are acid spots on the surface of the silicon material, such as Figure 3 As shown, reduce the concentration of hydrofluoric acid in the acid solution until the acid spots on the silicon material surface disappear.

[0070] The pickling temperature can be kept stable until 170t of silicon material is cleaned. Figure 4 As shown, no acid spots are visible to the naked eye, the cleaning effect is good, and the silicon material thinning amount is 5-10μm. Under this value, the cleaning effect is guaranteed while the raw material loss is low.

[0071] Comparative Example 1

[0072] This comparative example provides a method for pickling a silicon material, comprising:

[0073] Acid washing: transfer the single crystal silicon recycled material to the acid washing tank according to each batch of about 150 kg for acid washing. The pickling time is 50 seconds. 60L of hydrofluoric acid (electron pole, mass fraction 49%) and 530L of nitric acid (electron pole, mass fraction 69%) are added to the acid washing tank.

[0074] After warm water rinsing and pickling, the silicon material is taken out of the pickling tank and transferred to the rinsing tank. During this period, the silicon material is exposed to the air for 30 seconds. The pickled silicon material is rinsed with 22°C water, rinsed with pure water, drained at high temperature and dried. The temperature of the drying step is 80°C and the pressure is 80MPa.

[0075] The silicon material is pickled by this comparative method. The temperature rises in the early stage of pickling. The unqualified rate of the first 5T single crystal silicon recycling material is 65%, the unqualified rate of the 5-15T single crystal silicon recycling material is 80%, and the unqualified rate of the 15-20T single crystal silicon recycling material is 70%. Figure 5 As shown, the arrow indicates the acid spot.

[0076] The temperature of the pickling solution in the pickling tank of the silicon material in the pickling method of Example 1 and Comparative Example 1 was monitored, and the results were as follows: Figure 6 As shown. Figure 6 In the early stage of pickling, the temperature of the pickling solution in the pickling tank will not rise significantly, and the temperature of the pickling solution is relatively stable.

[0077] Comparative Example 2

[0078] This comparative example provides a cleaning method for reducing acid spots on silicon materials. The only difference from Example 1 is that the cooling water machine is turned off and the initial acid washing solution temperature is 25°C.

[0079] After warm water rinsing and pickling, the silicon material is taken out of the pickling tank and transferred to the rinsing tank. During this period, the silicon material is exposed to the air for 30 seconds. The pickled silicon material is rinsed with 22°C water, rinsed with pure water, drained at high temperature and dried. The temperature of the drying step is 80°C and the pressure is 80MPa.

[0080] When the cooling water machine is turned off, the temperature of the acid solution rises sharply during the reaction. The temperature increase accelerates the reaction speed, increases the amount of acid volatilization, and reacts to produce a large amount of NO. The unqualified rate of the first 20T single crystal silicon recycling material reaches 90%. The volatilization of the acid solution increases, and the hydrofluoric acid and nitric acid in the tank are diluted. The dilution has a reverse effect on the subsequent acid replenishment and concentration adjustment.

[0081] Comparative Example 3

[0082] This comparative example provides a cleaning method for reducing acid spots on silicon materials. The only difference from Example 1 is that 30 L of hydrofluoric acid (electron, mass fraction 49%) and 550 L of nitric acid (electron, mass fraction 69%) are added to the pickling tank.

[0083] Comparative Example 4

[0084] This comparative example provides a cleaning method for reducing acid spots on silicon materials. The only difference from Example 1 is that 50L of hydrofluoric acid (electron, mass fraction 49%) and 550L of nitric acid (electron, mass fraction 69%) are added to the pickling tank.

[0085] Comparative Example 5

[0086] This comparative example provides a cleaning method for reducing acid spots on silicon materials. The only difference from Example 1 is that after the pickling of 20t of silicon material is completed, only 20L of electron electrode and 49% mass fraction of hydrofluoric acid are added to the pickling tank, and 300mL of hydrofluoric acid (electron electrode, mass fraction 49%) and 1200mL of nitric acid (electron electrode, mass fraction 69%) are not added to the pickling tank for every three batches of silicon material pickled.

[0087] Comparative Example 6

[0088] This comparative example provides a cleaning method for reducing acid spots on silicon materials. The only difference from Example 1 is that after the pickling of 20t of silicon material is completed, only 300mL of hydrofluoric acid (electron electrode, mass fraction 49%) and 1200mL of nitric acid (electron electrode, mass fraction 69%) are added to the pickling tank for every three batches of silicon material pickled, and 20L of electron electrode and 49% mass fraction of hydrofluoric acid are not added to the pickling tank.

[0089] The average thinning amount of the silicon material obtained by the pickling method in the above embodiments and comparative examples and the unqualified rate due to acid spots were statistically analyzed, and the results are shown in the following table.

[0090]

[0091]

[0092] Remark:

[0093] The eligibility criteria are:

[0094] ①. There is no non-silicon material attached to the surface of the monocrystalline silicon recycling material and no acid spots; the whitening and atomization area of ​​a single piece does not exceed 5CM 2 2. In a single piece of silicon material, the total whitening area and the total fogging area are both less than 5% of the area of ​​the single piece of silicon material;

[0095] ②Thinning amount 5-10um (Thinning amount test and calculation method: from a single piece of silicon material, take four samples with an area of ​​30-50mm and a thickness of 3mm and clean them. Calculate the weight difference before and after cleaning, and calculate the specific thinning amount through the mass, volume, and surface area formula);

[0096] ③. Diamond wire marks are not obvious: The specific standards are: crush the cleaned silicon material, take a sample with a side length of 3-8mm, and the total metal element content is ≤20ppbw; or take a sample with a side length of 8-50mm, and the total metal element content is ≤10ppbw; the detected elements include Fe, Cr, Ni, Cu, Zn, Na, Ca, Mg, K and Al.

[0097] In the embodiment of the present application, by optimizing the composition of the pickling solution, a complex is formed on the surface of the silicon material, and the complex is caused to separate from the silicon material during warm water rinsing, which is beneficial to reducing acid consumption and reducing the cost of pickling solution per unit volume; after cleaning, the surface of the silicon material is glossy and no acid spots are generated, and the yield of the oxide layer is increased to 100% in one cleaning, which improves the efficiency of oxide layer removal, and the surface quality of the silicon material is improved. The quality, crystallization rate and yield of the crystal rod prepared therefrom are also improved, and the rework cost is reduced. The silicon loss can be reduced by 0.02%; the requirements for quality inspectors are reduced, the operation is convenient, and the amount of acid mist generated in the initial stage of pickling is small, which is beneficial to the improvement of the working environment.

[0098] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A cleaning method for reducing acid spots on silicon materials, characterized in that: include: Pickling: pickling the silicon material. The acid solution used for pickling includes hydrofluoric acid, nitric acid and water in a mass ratio of 1: (18-20): (9-10). The pickling temperature is 20°C-30°C and the pickling time is 40s-200s. Rinse with warm water: Use warm water at 25℃-80℃ to rinse the acid-washed silicon material, and then dry it; When the mass volume ratio of the silicon material after pickling to the acid solution is 33kg / L-35kg / L, a hydrofluoric acid solution is added to the acid solution, wherein the mass fraction of hydrofluoric acid in the hydrofluoric acid solution is 45%-50%; and the ratio of the volume of the added hydrofluoric acid solution to the volume of the acid solution is 0.33-0.35; When the mass volume ratio of the pickled silicon material to the acid solution reaches 33kg / L-35kg / L, add mixed acid to the acid solution. The mixed acid includes hydrofluoric acid, nitric acid and water in a mass ratio of 1:(5-6):(3-4); 0.9ml-1.1ml of mixed acid is added for every 0.3kg of silicon material to be pickled.

2. The cleaning method for reducing acid spots on silicon materials according to claim 1, characterized in that: The time that the silicon material is exposed to the air after pickling and before rinsing with warm water is less than 1 minute.

3. The cleaning method for reducing acid spots on silicon materials according to claim 1, characterized in that: The pickling is carried out in a pickling tank, which is provided with a circulating liquid inlet and a circulating liquid outlet, a circulating pipe is connected between the circulating liquid inlet and the circulating liquid outlet, and a cooling water machine is provided on the circulating pipe, which cools the liquid passing through it to 14°C-18°C.

4. The cleaning method for reducing acid spots on silicon materials according to claim 1, characterized in that: After the warm water rinsing, the silicon material is sequentially subjected to pure water rinsing, selective treatment and drying, wherein the selective treatment includes at least one of bubbling rinsing, wind shear drying and high-temperature drainage.

5. The cleaning method for reducing acid spots on silicon materials according to claim 1, characterized in that: The temperature of the drying step is 70°C-85°C and the pressure is less than 80 MPa.

6. The cleaning method for reducing acid spots on silicon materials according to claim 1, characterized in that: It also includes monitoring the thinning amount of the silicon material after drying relative to the silicon material before pickling: If the thinning amount is less than 5μm and the silicon material surface is white or atomized, add nitric acid to the acid solution; If the thinning amount is less than 5μm and the cut surface of the silicon material has non-silicon substances attached, is dark, or has obvious diamond wire marks, add hydrofluoric acid to the acid solution; If the thinning amount is greater than 10μm and there are acid spots on the surface of the silicon material, reduce the concentration of hydrofluoric acid in the acid solution.

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