Polished monocrystalline silicon wafer, polishing method and polishing device

Abstract

The invention provides a polished monocrystalline silicon wafer, a polishing method and a polishing device.The polishing method comprises the following steps that under the illumination environment, etching liquid containing HF and Cl2 is used for making contact with the surface of the monocrystalline silicon wafer, and the polished monocrystalline silicon wafer is obtained. The polishing method provided by the invention has the advantages that the polishing etching rate is high, and the polishing flatness of the polished monocrystalline silicon wafer is high.

Description

Technical Field

[0001] The present invention relates to a single crystal silicon wafer polishing method, in particular to a polished single crystal silicon wafer, a polishing method and a polishing device, and belongs to the field of new energy. Background Art

[0002] Wet chemical processing technology plays an important role in the production of single-crystal solar cells. This includes wet processing processes such as damage layer removal (SDE), cleaning and texturing, and backside polishing. The main purpose of backside polishing of single-crystal silicon wafers is to improve the reflectivity of the backside of the silicon wafer. The velvet pyramid structure on the backside of the single-crystal silicon wafer is converted into a planar structure through isotropic alkaline etching. Through this change, the backside polishing process reduces the specific surface area of ​​the backside of the cell, thereby reducing the recombination of minority carriers, increasing the open-circuit voltage of the solar cell, and thus improving the photovoltaic conversion efficiency of the solar cell. On the other hand, it enhances the specular reflection of light on the backside of the cell, increases the optical path of long wavelengths within the cell, and increases the long-wave absorption of the cell, thereby increasing the short-circuit current and improving the efficiency of the cell.

[0003] Currently, the wet chemical backside polishing process uses an alkaline etching system (NaOH / KOH). The alkaline polishing tank is filled with pure water, and an appropriate amount of NaOH / KOH solution and alkaline polishing additives (NaOH / KOH solution concentration is approximately 1.6%, polishing agent concentration is approximately 0.97%) are added. The silicon wafer is then subjected to alkaline etching polishing at an operating temperature of approximately 80°C, and the process time is between 180-240 seconds. Alkaline polishing is followed by a pure water rinse. The chemical reaction during the alkaline polishing process is as follows: Si + 2NaOH + 2H2O = Na2SiO3 + 2H2↑. However, this method suffers from a slow etching rate.

[0004] Therefore, developing a single crystal silicon wafer polishing method with a higher polishing and etching rate has become a research direction in this field. Summary of the Invention

[0005] The invention provides a single crystal silicon wafer polishing method, which has the characteristics of high polishing and etching rate.

[0006] The present invention also provides a polished single crystal silicon wafer, which has the characteristic of high flatness.

[0007] The present invention also provides a single crystal silicon wafer polishing device, which has the characteristic of being able to quickly etch silicon wafers.

[0008] The present invention provides a method for polishing a single crystal silicon wafer. In a light environment, an etching solution comprising HF and Cl2 is brought into contact with the surface of the single crystal silicon wafer to obtain a polished single crystal silicon wafer.

[0009] In the single crystal silicon wafer polishing method as described above, the concentration of Cl2 in the etching solution is 3g / L-5g / L.

[0010] The above-mentioned single crystal silicon wafer polishing method, wherein the illumination intensity of the illumination environment is 700W / m 2 -1400W / m 2 .

[0011] In the above-mentioned method for polishing a single crystal silicon wafer, the concentration of HF in the etching solution is 22 wt%-30 wt%.

[0012] In the above-mentioned method for polishing a single crystal silicon wafer, the contact time between the etching solution and the surface of the single crystal silicon wafer is 200-1000 seconds.

[0013] In the above-mentioned method for polishing a single crystal silicon wafer, the etching solution is sprayed to form droplets that contact the surface of the single crystal silicon wafer.

[0014] The single crystal silicon wafer polishing method as described above, wherein the flow rate of the etching solution is 20 mL / cm 2 / s-50mL / cm 2 / s.

[0015] Another aspect of the present invention provides a polished single crystal silicon wafer produced using the above method.

[0016] The polished single crystal silicon wafer as described above, wherein the reflectivity of the polished surface of the polished single crystal silicon wafer is ≥40%.

[0017] Another aspect of the present invention provides a polishing device for performing the above method, comprising a hydrogen fluoride supply unit, a chlorine gas supply unit, a spray unit, and a lighting unit;

[0018] The outlet of the hydrogen fluoride supply unit and the outlet of the chlorine supply unit are respectively communicated with the inlet of the spray unit.

[0019] The polishing device as described above, wherein further comprising a driving unit;

[0020] The inlet of the driving unit is communicated with the outlet of the hydrogen fluoride supply unit and / or the chlorine gas supply unit, and the outlet of the driving unit is communicated with the inlet of the spray unit.

[0021] The polishing device as described above, wherein, further comprises a silicon wafer carrying unit, wherein the silicon wafer carrying unit is arranged opposite to the spray unit and the lighting unit.

[0022] In response to the problem of slow etching rate in the existing wet chemical backside polishing process, the single crystal silicon wafer polishing method provided by the present invention uses an etching solution including HF and Cl2 to contact the surface of the single crystal silicon wafer under light conditions, and utilizes the acceleration effect of the chlorine radical chain reaction under light, which has the characteristic of a higher polishing and etching rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of polishing a single crystal silicon wafer using a polishing device provided by the third aspect of the present invention;

[0024] Figure 2 This is an SEM image of the single crystal silicon wafer in Example 1 before polishing;

[0025] Figure 3 This is the SEM image of polished single crystal silicon wafer A1;

[0026] Figure 4 This is the SEM image of the single crystal silicon wafer in Comparative Example 1 before polishing;

[0027] Figure 5 This is the SEM image of polished single crystal silicon wafer B1.

[0028] Description of Reference Numerals

[0029] 1- Waste gas emission treatment pipe; 2- Atomizing nozzle; 3- HF-Cl2 mixed gas spray; 4- Single crystal silicon wafer; 5- Perforated silicon wafer carrier substrate; 6- Liquid tank containing hydrogen fluoride solution; 7- Diaphragm pump; 8- Reflux circulation pipeline; 9- Chlorine gas source; 10- Xenon lamp; 11- Static mixer; 12- HF-Cl2 mixed liquid drainage pipeline. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0031] At present, the wet chemical back-side polishing process often adopts an alkaline solution etching system, which uses the alkaline solution to react with silicon to generate sodium silicate and hydrogen to polish the back of the single crystal silicon wafer. However, this polishing method has the defect of a slow etching rate. The single crystal silicon wafer polishing method provided by the first aspect of the present invention uses an etching solution including HF and Cl2 to contact the surface of the single crystal silicon wafer under a light environment to obtain a polished single crystal silicon wafer. It is understandable that the etching solution includes a solvent in addition to HF and Cl2, and the solvent is used to dissolve HF and Cl2. The present invention does not limit the type of solvent, as long as it meets the requirement of being able to dissolve HF and Cl2. In one embodiment, the solvent is water, and the etching solution consists of water, HF and Cl2 dissolved in water.

[0032] The single-crystal silicon wafer polishing method provided by the first aspect of the present invention has a high etching rate. This is because when the etching solution contains only hydrogen fluoride in addition to the solvent, the hydrogen fluoride can etch the single-crystal silicon wafer at a relatively slow rate, generating silicon tetrafluoride and hydrogen. When the etching solution contains both hydrogen fluoride and chlorine in addition to the solvent, the chlorine can decompose into chlorine radicals (Cl·) under light. The hydrogen generated by the reaction of hydrogen fluoride with the single-crystal silicon wafer undergoes a chain reaction with the chlorine radicals (Cl·), releasing a large amount of heat. The specific reaction mechanism is as follows:

[0033] 1) Photolysis of chlorine to produce chlorine free radicals: Cl2—(light)—2Cl·;

[0034] 2) Chlorine radicals react with hydrogen to form hydrogen chloride and new hydrogen radicals: Cl·+H2—HCl+H· (exothermic);

[0035] 3) The hydrogen radical reacts with chlorine to generate hydrogen chloride and another chlorine radical, maintaining the chain reaction: H·+Cl2—HCl+Cl· (exothermic);

[0036] 4) Chain termination reaction occurs when free radicals combine: Cl·+Cl·—Cl2 (exothermic), or, H·+H·—H2 (exothermic) or Cl·+H·—HCl (exothermic).

[0037] In the high-temperature environment generated by the reaction of hydrogen and chlorine, the reaction rate of the single-crystal silicon wafer and hydrogen fluoride is accelerated, so that the single-crystal silicon wafer polishing method provided by the first aspect of the present invention has the characteristic of a higher etching rate.

[0038] In addition, the above process also has the following secondary reactions:

[0039] Under heating conditions, chlorine (Cl2) reacts with single crystal silicon wafers (Si) to form silicon tetrachloride (SiCl4) in an exothermic reaction: Si + 2Cl2 - SiCl4 (exothermic);

[0040] Subsequently, silicon tetrachloride (SiCl4) exchanges halogens with hydrogen fluoride (HF) in the system to generate a series of fluorine-containing silicon compounds, such as silicon tetrafluoride (SiF4): SiCl4+4HF—SiF4+2H2, and silicon tetrafluoride reacts with hydrofluoric acid to generate hexafluorosilicic acid (H2SiF6): SiF4+2HF→H2SiF6, and a series of secondary reactions.

[0041] The above-mentioned polishing method for single crystal silicon wafers has the following advantages: 1) Compared with conventional alkaline polishing methods, this polishing method has the advantages of faster polishing rate and better polishing effect; 2) Compared with chemical mechanical polishing (CMP), this polishing method has the advantages of lower cost and faster polishing rate; 3) This polishing method is a room temperature process and does not require heating, which is conducive to energy saving; 4) Crystalline silicon / perovskite tandem cells require a highly flat substrate, and this polishing method can provide a feasible process for planar polishing substrates of crystalline silicon / perovskite tandem cells.

[0042] To further improve the etching rate of the single-crystal silicon wafer polishing method provided by the first aspect of the present invention, the Cl2 concentration in the etching solution is 3g / L-5g / L. This chlorine concentration not only generates a high concentration of chlorine free radicals under illumination, further improving the etching rate of the single-crystal silicon wafer polishing method provided by the first aspect of the present invention, but also avoids safety hazards caused by chlorine overflow from the etching solution due to excessive chlorine concentration.

[0043] For example, the concentration of Cl2 in the etching solution may be 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L or 5 g / L, etc.

[0044] When the light intensity of the controlled lighting environment is 700W / m 2 -1400W / m 2 The single crystal silicon wafer polishing method provided by the first aspect of the present invention can have a higher etching rate because the appropriate light intensity will not produce excessive chlorine free radicals due to excessive light intensity, resulting in a runaway reaction, and more chlorine free radicals can be obtained by promoting the decomposition of chlorine gas, thereby making the single crystal silicon wafer polishing method provided by the first aspect of the present invention have a higher etching rate.

[0045] For example, the illumination intensity of the illumination environment may be 700W / m 2 , 800W / m 2 , 900W / m 2 , 1000W / m 2 、1100W / m 2 , 1200W / m 2 、1300W / m 2 or 1400W / m 2 wait.

[0046] The inventors discovered that controlling the HF concentration in the etching solution to 22wt%-30wt% can achieve a higher etch rate while also resulting in a higher flatness of the resulting single-crystal silicon wafer compared to prior art methods. The flatness of the silicon wafer can be represented by the surface reflectivity, with higher reflectivity indicating higher flatness. The principle behind achieving higher reflectivity is that within this HF concentration range, hydrofluoric acid effectively reacts with the silicon wafer to produce silicon tetrafluoride (SiF4) and hydrogen (H2), thereby achieving a higher etch rate. Simultaneously, the etching solution more evenly etches the silicon wafer surface, reducing microscopic roughness and ultimately producing single-crystal silicon wafers with higher flatness.

[0047] For example, the concentration of HF in the etching solution may be 22 wt %, 26 wt %, 27 wt %, 28 wt %, 29 wt % or 30 wt %, etc.

[0048] To achieve higher efficiency in the single-crystal silicon wafer polishing method provided in the first aspect of the invention, the contact time between the etching solution and the single-crystal silicon wafer surface can be controlled to 200-1000 seconds. This appropriate contact time can remove the pyramidal structures on the back of the single-crystal silicon wafer and etch them into a planar structure, while also preventing excessive contact time from causing a loss in thickness of the single-crystal silicon wafer and reducing polishing efficiency. Thus, controlling the contact time between the etching solution and the single-crystal silicon wafer surface to 200-1000 seconds can further enhance the etching efficiency of the single-crystal silicon wafer polishing method provided in the first aspect of the invention.

[0049] For example, the contact time between the etching solution and the surface of the single crystal silicon wafer can be 200s, 250s, 300s, 350s, 400s, 500s, 600s, 700s, 800s, 900s or 1000s.

[0050] To further improve the etching rate of the single-crystal silicon wafer polishing method provided by the first aspect of the present invention, the etching solution can be sprayed to form droplets that contact the surface of the single-crystal silicon wafer, thereby etching the surface of the single-crystal silicon wafer. As the droplets formed by the spraying of the etching solution contact and react with the surface of the single-crystal silicon wafer, the concentrations of hydrogen fluoride and chlorine gas decrease. Due to the fluidity of the droplets, the low-concentration etching solution easily leaves its original position, which is occupied by the high-concentration droplets. The surface of the single-crystal silicon wafer can remain in contact with the high-concentration etching solution, thereby further improving the etching rate of the single-crystal silicon wafer polishing method.

[0051] The present invention does not limit the mechanism for executing the spray process. For example, an atomizing nozzle can be used to sputter the etching solution onto the surface of the silicon wafer being etched to achieve contact. Furthermore, the uniformity and etching rate of the etching reaction can be controlled by controlling the atomizing nozzle's spray angle, flow rate, pressure, and the distance between the nozzle and the single-crystal silicon wafer being etched. At a fixed distance, higher pressure increases the etching rate; at a fixed pressure, greater distance decreases the etching rate and improves etching uniformity.

[0052] In order to further improve the etching rate of the single crystal silicon wafer polishing method provided by the first aspect of the present invention, the flow rate of the etching solution is 20 mL / cm 2 / s-50mL / cm 2 / s. Where, mL / cm 2 / s refers to the volume of etching solution in milliliters per second per square centimeter of silicon wafer area. Controlling this flow rate increases the average concentration of etching solution in contact with the silicon wafer, thereby improving etching efficiency and avoiding waste caused by excessive flow rate.

[0053] For example, the flow rate of the etching solution can be 20 mL / cm 2 / s、25mL / cm 2 / s、30mL / cm 2 / s、35mL / cm 2 / s、40mL / cm 2 / s、45mL / cm 2 / s or 50mL / cm 2 / s, etc.

[0054] A second aspect of the present invention provides a polished single-crystal silicon wafer, produced using any of the single-crystal silicon wafer polishing methods provided in the first aspect of the present invention. The polished single-crystal silicon wafer provided in the second aspect of the present invention has a high reflectivity on its polished surface. Specifically, the reflectivity of the polished surface is greater than or equal to 40%, and the reflectivity of the polished surface can be measured using a standard 8-degree angular integrating reflectometer.

[0055] A third aspect of the present invention provides a single crystal silicon wafer polishing device, comprising a hydrogen fluoride supply unit, a chlorine gas supply unit, a spray unit, and a lighting unit. The outlets of the hydrogen fluoride supply unit and the chlorine gas supply unit are respectively connected to the inlet of the spray unit.

[0056] The hydrogen fluoride supply unit and the chlorine supply unit supply hydrogen fluoride and chlorine, respectively. It is understood that to facilitate the formation of the etching solution, the hydrogen fluoride supplied by the hydrogen fluoride supply unit can be dissolved in a solvent. The outlets of the hydrogen fluoride supply unit and the chlorine supply unit are respectively connected to the inlet of the spray unit. The etching solution containing dissolved hydrogen fluoride and chlorine is liquefied into droplets in the spray unit and sprayed onto the silicon wafer. The lighting unit is used to provide illumination for the reaction, promoting the decomposition of chlorine into chlorine radicals.

[0057] The present invention does not limit the specific equipment selection of the hydrogen fluoride supply unit, the chlorine supply unit, the spray unit, and the lighting unit. For example, the hydrogen fluoride supply unit can be a liquid tank containing hydrogen fluoride solution, the chlorine supply unit can be a chlorine bottle, the spray unit can be an atomizing nozzle, and the lighting unit can be a xenon lamp or an incandescent lamp.

[0058] When the device is used for polishing single-crystal silicon wafers, the hydrogen fluoride supply unit and the chlorine supply unit supply chlorine and hydrogen fluoride to the spray unit respectively. The spray unit atomizes the etching liquid containing chlorine and hydrogen fluoride into droplets and sprays them onto the silicon wafer, and etching is performed in the lighting environment provided by the lighting unit.

[0059] The single crystal silicon wafer polishing device provided in the third aspect of the present invention organically combines a hydrogen fluoride supply unit, a chlorine gas supply unit, a spray unit, and an illumination unit, thereby achieving a relatively high rate of etching of the single crystal silicon wafer.

[0060] To further improve the single crystal silicon wafer etching rate of the single crystal silicon wafer polishing device, the single crystal silicon wafer polishing device provided in the third aspect of the present invention may further include a drive unit, the outlet of the drive unit being connected to the inlet of the spray unit. The drive unit is used to adjust the pressure of the etching solution entering the spray unit, thereby achieving a higher spray pressure to improve the single crystal silicon wafer etching rate. The present invention does not limit the choice of equipment for the drive unit; any equipment that can meet the requirements for adjusting the pressure of the etching solution entering the spray unit is sufficient. For example, the drive unit may be a diaphragm pump.

[0061] In addition, the single crystal silicon wafer polishing device provided in the third aspect of the present invention further includes a silicon wafer carrier unit, which is arranged relative to the spray unit and the lighting unit. The silicon wafer carrier unit is used to carry the silicon wafer to be processed. The relative arrangement of the silicon wafer carrier unit, the spray unit, and the lighting unit means that the spray direction of the spray unit is toward the silicon wafer carrier unit, and the ejected etching liquid can contact the silicon wafer on the silicon wafer carrier unit; the light emitted by the lighting unit is directed toward the silicon wafer carrier unit, and the light can be used for etching reaction. The present invention does not limit the specific device selection of the silicon wafer carrier unit. For example, it can be a perforated silicon wafer carrier substrate.

[0062] Figure 1 FIG. 1 is a schematic diagram of the present invention using a polishing device to polish a single crystal silicon wafer, as shown in FIG. Figure 1As shown, the device includes an exhaust gas treatment pipe 1, an atomizing nozzle 2, an HF-Cl2 mixed gas spray 3, a single crystal silicon wafer 4, a perforated silicon wafer support substrate 5, a liquid tank containing hydrogen fluoride solution 6, a diaphragm pump 7, a reflux circulation pipeline 8, a chlorine gas source 9, a xenon lamp 10, and a static mixer 11. The exhaust gas treatment pipe 1, the atomizing nozzle 2, the reflux circulation pipeline 8, and the static mixer constitute the spray unit 11, the perforated silicon wafer support substrate 5 constitutes the silicon wafer support unit, the liquid tank containing hydrogen fluoride solution 6 constitutes the hydrogen fluoride supply unit, the chlorine gas source 9 constitutes the chlorine gas supply unit, the diaphragm pump 7 constitutes the drive unit, and the xenon lamp 10 constitutes the lighting unit.

[0063] like Figure 1 As shown, when the device is working, under the action of the diaphragm pump 7, the static mixer 11 mixes the chlorine gas introduced by the chlorine source 9 and the hydrogen fluoride solution in the reflux circulation pipeline 8 to obtain an etching solution; the etching solution continues to flow through the pipeline to reach the atomizing nozzle 2, and the atomizing nozzle 2 atomizes the etching solution and sputters the spray through the nozzle to the surface of the etched silicon wafer placed on the upper surface of the perforated silicon wafer carrier substrate 5. Under the action of the xenon lamp 10, chemical reaction contact is achieved (the uniformity of the etching reaction and the etching rate are regulated by controlling the angle, flow rate, pressure of the nozzle spray and the distance between the nozzle and the etched single crystal silicon wafer. At a fixed distance, the higher the pressure, the higher the corresponding etching rate; at a fixed pressure, the longer the distance, the lower the etching rate, and the better the etching uniformity at this time), and finally the surface of the single crystal silicon wafer is etched to a certain depth.

[0064] The by-products produced by the reaction mainly include hydrochloric acid (HCl) and hydrogen (H2). The hydrochloric acid flows into the lower liquid medicine pool 6 through the perforated silicon wafer carrier substrate 5, and the generated hydrogen is discharged through the waste gas discharge treatment pipe 1 for treatment.

[0065] The single crystal silicon wafer polishing method and its application provided by the present invention are further illustrated by examples below.

[0066] Example 1

[0067] This embodiment uses Figure 1 The equipment shown is used to etch single crystal silicon wafers.

[0068] like Figure 1As shown, the device includes an exhaust gas treatment pipe 1, an atomizing nozzle 2, an HF-Cl2 mixed gas spray 3, a single crystal silicon wafer 4, a perforated silicon wafer support substrate 5, a liquid tank containing hydrogen fluoride solution 6, a diaphragm pump 7, a reflux circulation pipeline 8, a chlorine gas source 9, a xenon lamp 10, and a static mixer 11. The exhaust gas treatment pipe 1, the atomizing nozzle 2, the reflux circulation pipeline 8, and the static mixer constitute the spray unit 11, the perforated silicon wafer support substrate 5 constitutes the silicon wafer support unit, the liquid tank containing hydrogen fluoride solution 6 constitutes the hydrogen fluoride supply unit, the chlorine gas source 9 constitutes the chlorine gas supply unit, the diaphragm pump 7 constitutes the drive unit, and the xenon lamp 10 constitutes the lighting unit.

[0069] like Figure 1 As shown, when the device is working, under the action of the diaphragm pump 7, the static mixer 11 mixes the chlorine gas introduced from the chlorine source 9 and the hydrogen fluoride solution in the reflux circulation pipeline 8 to obtain an etching solution; the etching solution continues to flow through the pipeline to reach the atomizing nozzle 2, the atomizing nozzle 2 atomizes the etching solution and then sputters the spray through the nozzle onto the surface of the etched silicon wafer placed on the upper surface of the perforated silicon wafer supporting substrate 5. Under the action of the xenon lamp 10, chemical reaction contact is achieved, and finally the surface of the single crystal silicon wafer is etched to a certain depth to obtain a polished single crystal silicon wafer A1.

[0070] The picture of single crystal silicon wafer before polishing is Figure 2 ;

[0071] Polished single crystal silicon wafer A1 picture is Figure 3 .

[0072] In Example 1:

[0073] The temperature of the etching solution is 25°C;

[0074] The concentration of Cl2 in the etching solution is 3g / L;

[0075] The light intensity of the lighting environment is 1000W / m 2 ;

[0076] The concentration of HF in the etching solution is 22 wt%;

[0077] The contact time between the etching solution and the surface of the single crystal silicon wafer is 10 minutes;

[0078] The flow rate of the etching solution is 30mL / cm 2 / s;

[0079] The reflectivity of the polished surface of the polished single crystal silicon wafer is 36.1%.

[0080] Comparative Example 1

[0081] In this comparative example, a sodium hydroxide alkaline polishing method was used to polish a single crystal silicon wafer. Specifically, a sodium hydroxide solution with a concentration of 22 wt% was used to perform alkaline etching polishing on the single crystal silicon wafer at an operating temperature of 80°C for the same operating time as in Example 1, yielding a polished single crystal silicon wafer B1.

[0082] The picture of single crystal silicon wafer before polishing is Figure 4 ;

[0083] Single crystal polished silicon wafer B1 picture is Figure 5 ;

[0084] The reflectivity of the polished surface of the polished single crystal silicon wafer is 30.4%.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for polishing a single crystal silicon wafer, characterized in that: The following steps are involved: In a light environment, an etching solution including HF and Cl2 is used to contact the surface of the single crystal silicon wafer to obtain a polished single crystal silicon wafer.

2. The polishing method according to claim 1, wherein The concentration of Cl2 in the etching solution is 3g / L-5g / L.

3. The polishing method according to claim 1 or 2, characterized in that The illumination intensity of the illumination environment is 700W / m 2 -1400W / m 2 .

4. The polishing method according to any one of claims 1 to 3, characterized in that The concentration of HF in the etching solution is 22 wt%-30 wt%.

5. The polishing method according to any one of claims 1 to 4, characterized in that The contact time between the etching solution and the surface of the single crystal silicon wafer is 200-1000s.

6. The polishing method according to any one of claims 1 to 5, characterized in that The etching solution is sprayed to form droplets that contact the surface of the single crystal silicon wafer.

7. The polishing method according to claim 6, characterized in that The flow rate of the etching solution is 20 mL / cm 2 / s-50mL / cm 2 / s.

8. A polished single crystal silicon wafer, characterized in that: It is prepared using the polishing method according to any one of claims 1 to 7.

9. The polished single crystal silicon wafer according to claim 8, characterized in that: The reflectivity of the polished surface of the polished single crystal silicon wafer is ≥40%.

10. A polishing device for performing the method according to any one of claims 1 to 7, characterized in that: It includes a hydrogen fluoride supply unit, a chlorine supply unit, a spray unit, and a lighting unit; The outlet of the hydrogen fluoride supply unit and the outlet of the chlorine gas supply unit are respectively communicated with the inlet of the spray unit.

11. The polishing device according to claim 10, characterized in that Also includes a drive unit; The inlet of the driving unit is communicated with the outlet of the hydrogen fluoride supply unit and / or the chlorine gas supply unit, and the outlet of the driving unit is communicated with the inlet of the spray unit.

12. The polishing device according to claim 10 or 11, characterized in that: It also includes a silicon wafer carrying unit, which is arranged opposite to the spray unit and the lighting unit.

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