Small tower footing monocrystalline silicon alkali polishing additive and use method thereof

Abstract

The invention discloses a small tower footing monocrystalline silicon alkali polishing additive and a use method thereof, and belongs to the technical field of alkali polishing, the small tower footing monocrystalline silicon alkali polishing additive comprises the following raw materials by weight: 0.3-2% of a polishing agent, 0.5-2% of a corrosion and scale inhibitor, 0.5-1% of a defoaming agent, 0.1-0.5% of a surfactant, 0.1-0.5% of a eutectic solvent, and the balance of deionized water. The small-tower-footing monocrystalline silicon alkali polishing additive provided by the invention can effectively protect a non-polished surface and control the reaction rate of a polished surface in a silicon wafer polishing process, ensures that a uniform small-size tower footing structure is formed after alkali polishing, improves the contact effect of back slurry, improves a filling factor and improves the performance of a battery piece.

Description

Technical Field

[0001] The invention belongs to the technical field of alkali polishing, and in particular relates to a small tower base single crystal silicon alkali polishing additive and a use method thereof. Background Art

[0002] Photovoltaic power generation is the current mainstream power generation technology. Among the core solar cell products, TOPCon cells have shown broad development potential due to their high photoelectric conversion efficiency, low cost and simple process. In the production process of TOPCon cells, by polishing the back of the silicon wafer, the reflectivity can be effectively reduced, and the contact between the aluminum paste and the silicon wafer surface can be enhanced, thereby significantly improving the efficiency of the cell. The traditional TOPCon battery acid polishing process faces high costs and environmental pressures due to the large use of nitric acid and hydrofluoric acid, and the alkaline polishing process has gradually become the mainstream. However, alkaline polishing often causes deep corrosion to the silicon wafer, resulting in a larger base size of the pyramid structure. This is particularly prominent in the subsequent screen printing process. The larger base size will weaken the adhesion of the slurry on the pyramid base, thereby reducing the efficiency of the cell and affecting the overall performance.

[0003] At present, CN115948123A discloses a single crystal silicon alkali polishing additive and an alkali polishing method, which are composed of the following components in weight percentage: 2-4% reaction accelerator, 1-2% corrosion and scale inhibitor, 0.1-0.5% brightener, 0.01-0.03% wetting agent, 0.5-1% defoaming agent, and the balance is deionized water; the single crystal silicon alkali polishing additive and the alkali polishing method can achieve good polishing effect under low weight loss, reduce the fragmentation rate under the general trend of thinning, and improve the flatness and reflectivity of the back side after etching, but it is still difficult to control the size of the pyramid base after alkali polishing. Summary of the invention

[0004] The object of the present invention is to provide a small tower base single crystal silicon alkali polishing additive and a use method thereof, so as to reduce the size of the tower base obtained after alkali polishing of the silicon wafer and improve the performance of the battery cell.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] The invention provides a small tower base single crystal silicon alkali polishing additive, which comprises the following raw materials in weight percentage: 0.3-2% of a polishing agent, 0.5-2% of a corrosion and scale inhibitor, 0.5-1% of a degassing agent, 0.1-0.5% of a surfactant, 0.1-0.5% of a low eutectic solvent, and the balance is deionized water.

[0007] Furthermore, the polishing agent is at least one of 2,3-diaminopiperazine, 2-hydroxycinnamic acid and trishydroxymethylaminomethane.

[0008] The structure of 2,3-diaminopiperazine contains amino groups and piperazine rings, the structure of 2-hydroxycinnamic acid contains hydroxyl groups and carboxyl groups, and the structure of trishydroxymethylaminomethane contains hydroxyl groups and amino groups, all of which can form hydrogen bonds with polar groups on the surface of silicon wafers to form a film layer and regulate the rate of alkaline polishing.

[0009] Furthermore, the polishing agent is obtained by mixing 2,3-diaminopiperazine, 2-hydroxycinnamic acid and trishydroxymethylaminomethane in a mass ratio of 2-6:1-3:1.

[0010] The three different polishing agents can better form a film layer on the surface of silicon wafers when mixed due to the different groups in their structures. A mixture of 2,3-diaminopiperazine, 2-hydroxycinnamic acid and tris(hydroxymethyl)aminomethane in a specific mass ratio is used as a polishing agent to form a dynamic film layer on the surface of silicon wafers. In the early stage of polishing, 2,3-diaminopiperazine and 2-hydroxycinnamic acid are mainly used, and tris(hydroxymethyl)aminomethane is used as a supplement. The tris(hydroxymethyl)aminomethane molecule contains amino and hydroxyl groups and can accept or release hydrogen ions. When the solution is more alkaline, the hydroxyl groups in the tris(hydroxymethyl)aminomethane molecules on the surface of the silicon wafer release hydrogen ions, which plays a role in regulating pH, weakening the hydrogen bonding between 2,3-diaminopiperazine and 2-hydroxycinnamic acid, and reducing the interaction between molecules inside the film layer. The film layer is relatively loose, which is conducive to the polishing liquid to act better on the silicon wafer. In the later stage of polishing, tris(hydroxymethyl)aminomethane cooperates with the remaining 2,3-diaminopiperazine and 2-hydroxycinnamic acid to assist each other in forming a compact film layer on the surface of the silicon wafer, which can reduce the contact rate between the polishing liquid and the silicon wafer surface, control the reaction rate of the silicon wafer, prevent the silicon wafer surface from being excessively corroded, effectively reduce the size of the tower base obtained after alkaline polishing, and improve the performance of the battery cell.

[0011] Furthermore, the corrosion and scale inhibitor is at least one of polyepoxysuccinic acid, polyacrylic acid, sodium ethylenediaminetetramethylenephosphonate and hydroxyethylidene diphosphonic acid.

[0012] Furthermore, the defoaming agent is plant polysaccharide.

[0013] Furthermore, the plant polysaccharide is at least one of ginkgo leaf polysaccharide, lotus leaf polysaccharide, Poria cocos polysaccharide, licorice polysaccharide, aloe polysaccharide, yam polysaccharide, and apple polysaccharide.

[0014] The degassing agent can be adsorbed on the surface of the silicon wafer, reduce the surface tension of the polishing liquid, accelerate the desorption of hydrogen during the reaction, and increase the fluidity of the bubbles in the liquid so that the bubbles are more likely to rise to the liquid surface and burst; the present invention preferably uses plant polysaccharides as the degassing agent, and the plant polysaccharide molecules can penetrate into the liquid film of the foam, destroy the elasticity of the foam and promote the bursting of the foam, while being easy to clean without residue.

[0015] Furthermore, the surfactant is at least one of sodium dodecylbenzene sulfonate, monolauryl phosphate, alcohol ether phosphate, and polyoxyethylene alkylphenol ether.

[0016] Surfactants can significantly reduce the surface tension of the polishing solution, improve the wettability of the silicon wafer surface, help improve the wettability of the polishing solution to the silicon wafer, and increase the rate of the alkali polishing reaction.

[0017] Furthermore, the deep eutectic solvent is obtained by mixing isopropanolamine, choline chloride and thiourea in a molar ratio of 0.5-1:1:1-3.

[0018] The hydrogen bond donors (isopropanolamine and thiourea) in the deep eutectic solvent form hydrogen bonds with the hydrogen bond acceptors (choline chloride), which have a good dissolving effect and increase the polarity of the polishing liquid. This not only promotes the polishing liquid to penetrate into the silicon wafer surface better, but also helps the polishing product to quickly detach from the silicon wafer surface, ensuring the cleanliness of the silicon wafer surface.

[0019] The present invention also provides a method for using the small tower base single crystal silicon alkali polishing additive as described above, comprising the following steps:

[0020] S1. Preparing additives: adding polishing agent, corrosion inhibitor, defoaming agent, surfactant and low eutectic solvent into deionized water according to the formula, and mixing them evenly to obtain alkaline polishing additives;

[0021] S2, preparing a polishing liquid: adding the alkali polishing additive prepared in step S1 into the alkali solution, and mixing them evenly to obtain a polishing liquid;

[0022] S3, silicon wafer polishing: polishing the back of the silicon wafer using the polishing liquid prepared in step S2, 抛 The temperature of light treatment is 60-65°C and the time is 180-240s.

[0023] Furthermore, in step S2, the mass ratio of the alkali polishing additive to the alkali solution is 7-10:500.

[0024] Furthermore, in step S2, the alkali solution is a NaOH solution or a KOH solution, and the mass concentration of the alkali solution is 4-6%.

[0025] Beneficial effects of the present invention:

[0026] (1) The small tower base single crystal silicon alkaline polishing additive of the present invention can effectively protect the non-polished surface and control the reaction rate of the polished surface during the silicon wafer polishing process, ensure the formation of a uniform small-sized tower base structure after alkaline polishing, enhance the contact effect of the back slurry, enhance the filling factor, and improve the performance of the battery cell.

[0027] (2) The 2,3-diaminopiperazine, 2-hydroxycinnamic acid and trishydroxymethylaminomethane of the present invention can all regulate the reaction rate between the alkali and the silicon wafer, improve the uniformity and flatness of the silicon wafer surface, improve the polishing effect, play a major role in forming a small tower base silicon wafer, and improve the performance of the battery cell.

[0028] (3) The degassing agent of the present invention is combined with a surfactant to reduce the interfacial tension of the gas-liquid-solid three-phase interface, so that the bubbles generated by the reaction quickly leave the surface of the silicon wafer, avoiding the formation of micro-pits on the silicon surface caused by the shock wave generated when the bubbles burst, thereby improving the surface quality of the silicon wafer.

[0029] (4) During the polishing process of the present invention, the low eutectic solvent causes uneven distribution of stress on the surface of the silicon wafer by the polishing liquid, and cooperates with the polishing agent to further adjust the polishing rate of the local area of ​​the silicon wafer surface, so that the polishing rate on the (100) crystal plane of silicon is slower, and the polishing rate on the (111) crystal plane is faster, which is more conducive to obtaining a smaller and more uniform tower base structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below in conjunction with the accompanying drawings.

[0031] Figure 1 This is a scanning electron microscope image of the back side of the silicon wafer obtained after alkali polishing in Example 1 of the present invention;

[0032] Figure 2 This is a scanning electron microscope image of the back side of the silicon wafer obtained after alkali polishing in Example 4 of the present invention;

[0033] Figure 3 This is a scanning electron microscope image of the back side of the silicon wafer obtained after alkali polishing in Example 5 of the present invention;

[0034] Figure 4 This is a scanning electron microscope image of the back side of the silicon wafer obtained after alkali polishing in Example 6 of the present invention;

[0035] Figure 5 This is a scanning electron microscope image of the back side of the silicon wafer obtained after alkali polishing in Comparative Example 1 of the present invention;

[0036] Figure 6 This is a scanning electron microscope image of the back side of the silicon wafer obtained after alkali polishing in Comparative Example 2 of the present invention;

[0037] Figure 7 This is a scanning electron microscope image of the back side of the silicon wafer obtained after alkali polishing in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] A silicon wafer alkali polishing additive for a small tower base, which is composed of the following components in weight percentage: 0.3% polishing agent, 0.5% corrosion and scale inhibitor, 0.5% degassing agent, 0.1% surfactant, 0.1% low eutectic solvent, and the balance is deionized water;

[0041] The polishing agent is obtained by mixing 2,3-diaminopiperazine and 2-hydroxycinnamic acid in a mass ratio of 2:1; the corrosion inhibitor and scale inhibitor is polyepoxysuccinic acid; the defoaming agent is lotus leaf polysaccharide; the surfactant is sodium dodecylbenzene sulfonate; and the low eutectic solvent is obtained by mixing isopropanolamine, choline chloride and thiourea in a molar ratio of 0.5:1:1.

[0042] A method for using a small tower base single crystal silicon alkali polishing additive in silicon wafer polishing comprises the following steps:

[0043] S1. Prepare additives: add polishing agent, corrosion inhibitor, defoaming agent, surfactant and low eutectic solvent into deionized water according to the formula, and mix them evenly to obtain alkali polishing additives;

[0044] S2, preparing a polishing liquid: adding the alkali polishing additive prepared in step S1 to a NaOH solution with a mass concentration of 4% at a mass ratio of 7:500, and mixing them evenly to obtain a polishing liquid;

[0045] S3, silicon wafer polishing: polishing the back side of the silicon wafer using the polishing liquid prepared in step S2, the polishing temperature is 60° C., and the time is 240 s.

[0046] The back scanning electron microscope image obtained after alkali polishing in Example 1 is as follows Figure 1 As shown, the tower base size was measured and found to be 6-8 μm.

[0047] Example 2

[0048] A silicon wafer alkali polishing additive for a small tower base, which is composed of the following components by weight percentage: 1.5% polishing agent, 1% corrosion and scale inhibitor, 0.8% degassing agent, 0.3% surfactant, 0.3% low eutectic solvent, and the balance is deionized water;

[0049] Among them, the polishing agent is obtained by mixing 2-hydroxycinnamic acid and trihydroxymethylaminomethane in a mass ratio of 2:1; the corrosion inhibitor and scale inhibitor is sodium ethylenediaminetetramethylenephosphonate; the defoaming agent is aloe polysaccharide; the surfactant is polyoxyethylene alkylphenol ether; and the low eutectic solvent is obtained by mixing isopropanolamine, choline chloride and thiourea in a molar ratio of 0.8:1:2.

[0050] An application of a small tower base single crystal silicon alkali polishing additive in silicon wafer polishing comprises the following steps:

[0051] S1. Prepare additives: according to the formula, add polishing agent, corrosion inhibitor, defoaming agent, surfactant and low eutectic solvent into deionized water, mix well to obtain alkali polishing additive;

[0052] S2, preparing a polishing liquid: adding the alkali polishing additive prepared in step S1 to a NaOH solution with a mass concentration of 5% at a mass ratio of 2:125, and mixing them evenly to obtain a polishing liquid;

[0053] S3, silicon wafer polishing: polishing the back side of the silicon wafer using the polishing liquid prepared in step S2, the polishing temperature is 63° C., and the time is 205 s.

[0054] The back surface obtained after alkali polishing in Example 2 was inspected by scanning electron microscopy to measure the size of the tower base, and the size of the tower base was 4.5-7.0 μm.

[0055] Example 3

[0056] A silicon wafer alkali polishing additive for a small tower base, which is composed of the following components by weight percentage: 2% polishing agent, 2% corrosion and scale inhibitor, 1% degassing agent, 0.5% surfactant, 0.5% low eutectic solvent, and the balance is deionized water;

[0057] The polishing agent is obtained by mixing 2,3-diaminopiperazine and tris(hydroxymethyl)aminomethane in a mass ratio of 6:1; the corrosion and scale inhibitor is hydroxyethylidene diphosphonic acid; the defoaming agent is Poria polysaccharide; the surfactant is monolauryl phosphate; and the low eutectic solvent is obtained by mixing isopropanolamine, choline chloride and thiourea in a molar ratio of 1:1:3.

[0058] An application of a small tower base single crystal silicon alkali polishing additive in silicon wafer polishing comprises the following steps:

[0059] S1. Prepare additives: according to the formula, add polishing agent, corrosion inhibitor, defoaming agent, surfactant and low eutectic solvent into deionized water, mix well to obtain alkali polishing additive;

[0060] S2, preparing a polishing liquid: adding the alkali polishing additive prepared in step S1 to a KOH solution with a mass concentration of 6% at a mass ratio of 1:50, and mixing them evenly to obtain a polishing liquid;

[0061] S3, silicon wafer polishing: polishing the back side of the silicon wafer using the polishing liquid prepared in step S2, the polishing temperature is 65° C., and the time is 180 s.

[0062] The back surface obtained after alkali polishing in Example 3 was inspected by scanning electron microscopy to measure the size of the tower base, and the size of the tower base was 4.0-6.5 μm.

[0063] Example 4

[0064] A silicon wafer alkali polishing additive for a small tower base, which is composed of the following components in weight percentage: 0.3% polishing agent, 0.5% corrosion and scale inhibitor, 0.5% degassing agent, 0.1% surfactant, 0.1% low eutectic solvent, and the balance is deionized water;

[0065] Among them, the polishing agent is obtained by mixing 2,3-diaminopiperazine, 2-hydroxycinnamic acid and trihydroxymethylaminomethane in a mass ratio of 2:1:1; the corrosion inhibitor and scale inhibitor is polyepoxysuccinic acid; the defoaming agent is lotus leaf polysaccharide; the surfactant is sodium dodecylbenzene sulfonate; and the low eutectic solvent is obtained by mixing isopropanolamine, choline chloride and thiourea in a molar ratio of 0.5:1:1.

[0066] An application of a small tower base single crystal silicon alkali polishing additive in silicon wafer polishing comprises the following steps:

[0067] S1. Prepare additives: according to the formula, add polishing agent, corrosion inhibitor, defoaming agent, surfactant and low eutectic solvent into deionized water, mix well to obtain alkali polishing additive;

[0068] S2, preparing a polishing liquid: adding the alkali polishing additive prepared in step S1 to a NaOH solution with a mass concentration of 4% at a mass ratio of 7:500, and mixing them evenly to obtain a polishing liquid;

[0069] S3, silicon wafer polishing: polishing the back side of the silicon wafer using the polishing liquid prepared in step S2, the polishing temperature is 60° C., and the time is 240 s.

[0070] The back scanning electron microscope image obtained after alkali polishing in Example 4 is as follows Figure 2 As shown, the tower base size was measured and found to be 4.5-6.0 μm.

[0071] Example 5

[0072] A silicon wafer alkali polishing additive for a small tower base, which is composed of the following components in weight percentage: 0.3% polishing agent, 0.5% corrosion and scale inhibitor, 0.5% degassing agent, 0.1% surfactant, 0.1% low eutectic solvent, and the balance is deionized water;

[0073] Among them, the polishing agent is obtained by mixing 2,3-diaminopiperazine, 2-hydroxycinnamic acid and trihydroxymethylaminomethane in a mass ratio of 5:2:1; the corrosion inhibitor and scale inhibitor is polyepoxysuccinic acid; the defoaming agent is lotus leaf polysaccharide; the surfactant is sodium dodecylbenzene sulfonate; and the low eutectic solvent is obtained by mixing isopropanolamine, choline chloride and thiourea in a molar ratio of 0.5:1:1.

[0074] An application of a small tower base single crystal silicon alkali polishing additive in silicon wafer polishing comprises the following steps:

[0075] S1. Prepare additives: according to the formula, add polishing agent, corrosion inhibitor, defoaming agent, surfactant and low eutectic solvent into deionized water, mix well to obtain alkali polishing additive;

[0076] S2, preparing a polishing liquid: adding the alkali polishing additive prepared in step S1 to a NaOH solution with a mass concentration of 4% at a mass ratio of 7:500, and mixing them evenly to obtain a polishing liquid;

[0077] S3, silicon wafer polishing: polishing the back side of the silicon wafer using the polishing liquid prepared in step S2, the polishing temperature is 60° C., and the time is 240 s.

[0078] The back scanning electron microscope image obtained after alkali polishing in Example 5 is as follows Figure 3 As shown, the tower base size was measured and found to be 4.5-5.5 μm.

[0079] Example 6

[0080] A silicon wafer alkali polishing additive for a small tower base, which is composed of the following components in weight percentage: 0.3% polishing agent, 0.5% corrosion and scale inhibitor, 0.5% degassing agent, 0.1% surfactant, 0.1% low eutectic solvent, and the balance is deionized water;

[0081] Among them, the polishing agent is obtained by mixing 2,3-diaminopiperazine, 2-hydroxycinnamic acid and trihydroxymethylaminomethane in a mass ratio of 6:3:1; the corrosion inhibitor and scale inhibitor is polyepoxysuccinic acid; the defoaming agent is lotus leaf polysaccharide; the surfactant is sodium dodecylbenzene sulfonate; and the low eutectic solvent is obtained by mixing isopropanolamine, choline chloride and thiourea in a molar ratio of 0.5:1:1.

[0082] An application of a small tower base single crystal silicon alkali polishing additive in silicon wafer polishing comprises the following steps:

[0083] S1. Prepare additives: according to the formula, add polishing agent, corrosion inhibitor, defoaming agent, surfactant and low eutectic solvent into deionized water, mix well to obtain alkali polishing additive;

[0084] S2, preparing a polishing liquid: adding the alkali polishing additive prepared in step S1 to a NaOH solution with a mass concentration of 4% at a mass ratio of 7:500, and mixing them evenly to obtain a polishing liquid;

[0085] S3, silicon wafer polishing: polishing the back side of the silicon wafer using the polishing liquid prepared in step S2, the polishing temperature is 60° C., and the time is 240 s.

[0086] The back scanning electron microscope image obtained after alkali polishing in Example 6 is as follows Figure 4 As shown, the tower base size was measured and found to be 4.5-6.0 μm.

[0087] Comparative Example 1

[0088] The only difference between Comparative Example 1 and Example 1 is that the low eutectic solvent is replaced by a polishing agent of equal mass.

[0089] The back scanning electron microscope image obtained after alkali polishing of Comparative Example 1 is as follows Figure 5 As shown, the tower base size was measured and found to be 9.5-11.0 μm.

[0090] Comparative Example 2

[0091] The only difference between Comparative Example 2 and Example 1 is that the polishing agent is replaced by a low eutectic solvent of equal mass.

[0092] The back scanning electron microscope image obtained after alkali polishing of Comparative Example 2 is as follows Figure 6 As shown, the tower base size was measured and found to be 9.5-11.5 μm.

[0093] Comparative Example 3

[0094] The difference between Comparative Example 3 and Example 1 is that the deep eutectic solvent is obtained by mixing choline chloride and thiourea in a molar ratio of 1:2.

[0095] The back scanning electron microscope image obtained after alkali polishing of Comparative Example 3 is as follows Figure 7 As shown, the tower base size was measured and found to be 8.5-10.0 μm.

[0096] The tower base size obtained after alkali polishing in Example 1 is 6-8 μm, the tower base size obtained after alkali polishing in Example 4 is 4.5-6.0 μm, the tower base size obtained after alkali polishing in Example 5 is 4.5-5.5 μm, and the tower base size obtained after alkali polishing in Example 6 is 4.5-6.5 μm. By comparing Example 1 with Examples 4-6, it can be obtained that under the same conditions such as alkali polishing time, the tower base size after alkali polishing is significantly reduced with the adjustment of the polishing agent composition. A smaller tower base size can improve the contact effect of the back slurry of the screen-printed battery cell, and at the same time improve the filling factor, thereby improving the performance of the battery cell. Combining Example 1 with Comparative Examples 1-2, it can be seen that the polishing agent and the low eutectic solvent synergize to improve the polishing effect of the silicon wafer, achieve high-selectivity polishing, and help to form a smaller tower base size, so that the back of the single crystal silicon has excellent flatness and reflectivity after polishing, thereby improving the conversion efficiency of the battery. Comparative Example 3 replaces the low eutectic solvent with choline chloride and thiourea on the basis of Example 1. The size of the tower base formed in Example 1 is smaller than that in Comparative Example 3. Therefore, the three-component low eutectic solvent used in Example 1 is better than the two-component low eutectic solvent. Isopropanolamine, thiourea and choline chloride can work together to produce a more complete hydrogen bond network and more interstitial sites, improve the interaction between the polishing liquid and the silicon wafer surface, and better reduce the size of the tower base.

[0097] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0098] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A small tower base single crystal silicon alkali polishing additive, characterized in that: According to weight percentage, it includes the following raw materials: Polishing agent 0.3-2%, corrosion and scale inhibitor 0.5-2%, degassing agent 0.5-1%, surfactant 0.1-0.5%, low eutectic solvent 0.1-0.5%, and the balance is deionized water.

2. The small tower base single crystal silicon alkali polishing additive according to claim 1, characterized in that: The polishing agent is at least one of 2,3-diaminopiperazine, 2-hydroxycinnamic acid and trishydroxymethylaminomethane.

3. The small tower base single crystal silicon alkali polishing additive according to claim 2, characterized in that: The polishing agent is obtained by mixing 2,3-diaminopiperazine, 2-hydroxycinnamic acid and trishydroxymethylaminomethane in a mass ratio of 2-6:1-3:

1.

4. The small tower base single crystal silicon alkali polishing additive according to claim 1, characterized in that: The corrosion and scale inhibitor is at least one of polyepoxysuccinic acid, polyacrylic acid, sodium ethylenediaminetetramethylenephosphonate and hydroxyethylidene diphosphonic acid.

5. The small tower base single crystal silicon alkali polishing additive according to claim 1, characterized in that: The defoaming agent is plant polysaccharide; The plant polysaccharide is at least one of ginkgo leaf polysaccharide, lotus leaf polysaccharide, tuckahoe polysaccharide, licorice polysaccharide, aloe polysaccharide, yam polysaccharide and apple polysaccharide.

6. The small tower base single crystal silicon alkali polishing additive according to claim 1, characterized in that: The surfactant is at least one of sodium dodecylbenzene sulfonate, monolauryl phosphate, alcohol ether phosphate, and polyoxyethylene alkylphenol ether.

7. The small tower base single crystal silicon alkali polishing additive according to claim 1, characterized in that: The deep eutectic solvent is obtained by mixing isopropanolamine, choline chloride and thiourea in a molar ratio of 0.5-1:1:1-3.

8. A method for using the small tower base single crystal silicon alkali polishing additive according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Preparing additives: adding polishing agent, corrosion inhibitor, defoaming agent, surfactant and low eutectic solvent into deionized water according to the formula, and mixing them evenly to obtain alkaline polishing additives; S2, preparing a polishing liquid: adding the alkali polishing additive prepared in step S1 into the alkali solution, and mixing them evenly to obtain a polishing liquid; S3, silicon wafer polishing: polishing the back of the silicon wafer using the polishing liquid prepared in step S2, the polishing temperature is 60-65° C., and the time is 180-240 seconds.

9. The method for using the small tower base single crystal silicon alkali polishing additive according to claim 8, characterized in that: In step S2, the mass ratio of the alkali polishing additive to the alkali solution is 7-10:

500.

10. The method for using the small tower base single crystal silicon alkali polishing additive according to claim 8, characterized in that: In step S2, the alkali solution is a NaOH solution or a KOH solution, and the mass concentration of the alkali solution is 4-6%.

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