TWI583756B - Additive for crystalline silicon acidic polishing liquid and use thereof - Google Patents

Description

Additives for crystalline bismuth acidic polishing liquid and application thereof

The invention relates to an additive for a crystalline bismuth acidic polishing liquid and an application thereof.

In the fabrication process of the crystalline germanium solar cell, the backside polishing of the tantalum sheet has the following advantages: 1. Optical gain, which reflects the infrared light in the sunlight, so that the battery sheet absorbs more light, thereby making the battery sheet The short-circuit current is improved; 2. The back field is uniform, thereby increasing the open circuit voltage of the battery; 3. The back contact is improved, the contact between the back surface of the cymbal and the aluminum paste is improved, and a good ohmic contact is achieved; 4. a significant passivation effect, The combination of back passivation can significantly increase the efficiency of the cell.

At present, there are mainly three polishing methods used for polishing the back side of the ruthenium. The first one is inorganic alkali polishing. Although the cost is low and the polishing effect is good, it is necessary to make a tantalum nitride mask on the front side of the ruthenium sheet, and increase the PECVD coating process. Greatly reduced the production capacity of the production line. The second is polishing with tetramethylammonium hydroxide solution. Polishing by this method can protect the PN junction from damage by the protection of the front phosphor glass, while the backside polishing effect is better, but in the polishing process, tetramethyl Ammonium hydroxide is very expensive to consume and is highly toxic, which is detrimental to the production operating environment. The third type is polishing with nitric acid, hydrofluoric acid and sulfuric acid, which is less expensive and has a better polishing effect. However, the current production line uses a high concentration of acid to polish, on the one hand, a high concentration of acid mist will Corrosion of the front PN junction to a certain extent, and the plaque with a certain probability will be cuffed, so the yield is generally not high; on the other hand, the high concentration of acid not only causes an increase in manufacturing costs, but also makes the wastewater treatment cost of the plant Increased, has a certain impact on the environment.

Therefore, if a new acid polishing additive can be developed, it can be directly applied to the existing chain equipment to achieve the backside polishing of the cymbal, which can improve the polishing effect of the cymbal, improve the efficiency of the battery, and reduce the acid concentration and reduce the acid turnover. On the other hand, increasing the battery yield will make an important contribution to reducing the cost of the battery. This is also the result that battery manufacturers have been expecting for a long time, and it is also important for environmental protection.

The object of the present invention is to provide an additive for a crystalline bismuth acidic polishing liquid and an application thereof. When the enamel sheet is surface-polished, the additive of the present invention is added to an acidic solution to achieve an excellent polishing effect and can be used in a low acid. Polishing is achieved at a concentration.

In order to achieve the above object, the present invention provides an additive for a crystalline cerium acidic polishing liquid, which comprises 2 to 5 parts by mass of tartaric acid, 0.5 to 2.0 parts by mass of polyvinyl alcohol, 1 to 3 parts by mass of sodium sulfate, and 100 parts by mass of water. composition.

Preferably, the additive of the crystalline cerium acidic polishing liquid is composed of 2 to 3 parts by mass of tartaric acid, 0.5 to 1 part by mass of polyvinyl alcohol, 1 to 2 parts by mass of sodium sulfate, and 100 parts by mass of water.

Preferably, the water is deionized water.

The invention also provides a crystalline bismuth acidic polishing liquid prepared by the following steps: 1) dissolving an acid component in deionized water to prepare an acidic solution; the acid component comprises hydrofluoric acid, nitric acid; and the acid in the acidic solution The total mass percentage of the component is 22-55%; 2) adding the above additive to the acidic solution in the above step 1), A crystalline bismuth acid polishing solution; wherein the mass ratio of the additive to the acidic solution is 0.2 to 5:100.

Preferably, the total mass percentage of the acid component in the acidic solution is 27.5 to 45%; and the mass ratio of the additive to the acidic solution is 1 to 3:100.

Preferably, the mass fraction of hydrofluoric acid in the acid component is 10 to 25%, and the mass percentage of nitric acid is 75 to 90%.

Preferably, the acid component further comprises sulfuric acid; the mass percentage of hydrofluoric acid in the acid component is 2 to 5%, the mass percentage of nitric acid is 34 to 66%, and the mass percentage of sulfuric acid is It is 29~64%.

The invention also provides a crystallization enamel polishing method, wherein a single crystal or polycrystalline ruthenium sheet is immersed in the above polishing liquid for polishing, the temperature is controlled at 6 to 15 degrees Celsius, and the time is controlled in 30 seconds to 3 minutes.

An advantage and a beneficial effect of the present invention is to provide an additive for a crystalline bismuth acidic polishing liquid and an application thereof, which can achieve an excellent polishing effect by adding the additive of the present invention to an acidic solution when surface-polishing the ruthenium sheet, and Polishing can be achieved at low acid concentrations.

By using the additive of the invention, the polishing reaction speed can be accelerated, and the polishing can be achieved at a low acid concentration, and the acid consumption is 20-50%. In addition, a uniform flat suede can be obtained after polishing, which, in combination with the back passivation process, can significantly improve cell efficiency. The additive of the invention has wide application range, can be applied to the polishing of the single crystal bismuth sheet, and can also be applied to the polishing of the polycrystalline enamel sheet, and the reflectivity of the enamel sheet after polishing can reach 30-40%. The additive of the invention is compatible with the existing wet engraving equipment, and has a small polishing weight. For a 156*156 mm bract, the polishing weight is about 0.2-0.4 g (g), so as not to pollute the environment.

1 is a micrograph of a polished surface of a bract sheet obtained in Example 1 of the present invention; FIG. 2 is a reflection spectrum of a polished surface of a bract sheet obtained in Example 1 of the present invention; FIG. 3 is a batt obtained in Example 2 of the present invention; Microscopic photograph of the surface polished surface; Fig. 4 is a reflection spectrum of the polished surface of the bract sheet obtained in Example 2 of the present invention.

The specific embodiments of the present invention are further described below in conjunction with the drawings and embodiments. The following examples are only intended to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the scope of the present invention.

The technical solution specifically implemented by the present invention is:

Example 1

The crystallization crucible is polished by the following steps: 1) preparing an additive for the crystalline citric acid polishing solution: dissolving 2 g of tartaric acid, 0.5 g of polyvinyl alcohol and 1 gram of sodium sulfate in deionized water in 100 g (g) of deionized water as a solvent Adding an additive; 2) preparing an acidic solution: dissolving 50 g of hydrofluoric acid, 400 g of nitric acid and the like in deionized water to obtain 1000 g of an acidic solution; 3) preparing a crystalline bismuth acidic polishing liquid: acidic at 1000 g 10 g of the additive was added to the solution; 4) The single crystal crucible was immersed in a polishing liquid for surface polishing at a polishing temperature of 10 ° C and a polishing time of 2 minutes.

Fig. 1 is a photomicrograph showing the surface-polished surface of the single crystal ruthenium sheet obtained in Example 1, and it can be seen from Fig. 1 that a uniform smooth and flat surface structure is formed on the surface of the ruthenium sheet. 2 shows the reflection spectrum of the polished surface of the ruthenium sheet after polishing in Example 1. As can be seen from FIG. 2, the surface polished surface of the ruthenium obtained in Example 1 has a high reflectance at 300-1100 nm (nm). The integrated reflectance in the wavelength range is higher than 35%.

Example 2

The crystallization enamel is polished by the following steps: 1) Preparation of a crystalline phthalic acid polishing liquid Agent: 100 g of deionized water as solvent, 3 g of tartaric acid, 1 g of polyvinyl alcohol and 2 g of sodium sulfate dissolved in deionized water to prepare an additive; 2) formulating an acidic solution: 27.5 g of hydrofluoric acid, 330 g The acid component such as nitric acid and 192.5 g of sulfuric acid is dissolved in deionized water to obtain 1000 g of an acidic solution; 3) the crystalline cerium acidic polishing liquid is prepared: 50 g of an additive is added to 1000 g of the acidic solution; 4) the polycrystalline crucible is immersed in the polishing liquid. The surface was polished to a polishing temperature of 15 degrees Celsius and a polishing time of 45 seconds.

Fig. 3 is a photomicrograph showing the surface-polished surface of the polycrystalline silicon wafer obtained in Example 2. From Fig. 3, it can be seen that the surface of the ruthenium sheet has a uniform smooth and flat surface structure. 4 shows the reflection spectrum of the polished surface of the ruthenium sheet after polishing in Example 2. As can be seen from FIG. 4, the polished surface of the ruthenium sheet obtained in Example 2 has a high reflectance of 300-1100 nm (nm) wavelength. The integral reflectance in the range is higher than 33%.

Example 3

The crystallization enamel is polished by the following steps: 1) preparing an additive for the crystalline phthalic acid polishing solution: 100 g of deionized water as a solvent, 5 g of tartaric acid, 2 g of polyvinyl alcohol and 3 g of sodium sulfate are dissolved in deionized water to prepare Additive; 2) Prepare acidic solution: dissolve 55 grams of hydrofluoric acid, 165 grams of nitric acid and other acid components in deionized water to obtain 1000 grams of acidic solution; 3) prepare crystalline cerium acidic polishing solution: add in 1000 grams of acidic solution 30 g of additive; 4) The polycrystalline silicon flakes were immersed in a polishing liquid for surface polishing at a polishing temperature of 6 ° C and a polishing time of 30 seconds.

Example 4

The crystallization enamel is polished by the following steps: 1) preparing an additive for the crystalline phthalic acid polishing solution: using 100 g of deionized water as a solvent, 2.5 g of tartaric acid, 0.8 g of polyvinyl alcohol and 1.5 g of sodium sulfate are dissolved in deionized water to prepare Additive; 2) Prepare an acidic solution: dissolve 10 grams of hydrofluoric acid, 170 grams of nitric acid, 320 grams of sulfuric acid and other acid components In ionic water, 1000 g of acidic solution is obtained; 3) preparing crystalline bismuth acidic polishing liquid: adding 2 g of additive in 1000 g of acidic solution; 4) immersing polycrystalline enamel sheet in polishing liquid for surface polishing, polishing temperature is 10 degrees Celsius, polishing The time is 3 minutes.

Example 5

The crystallization enamel is polished by the following steps: 1) preparing an additive for the crystalline phthalic acid polishing liquid: 4 g of tartaric acid, 1.5 g of polyvinyl alcohol and 2.5 g of sodium sulfate are dissolved in deionized water using 100 g of deionized water as a solvent. Additive; 2) Prepare acidic solution: dissolve 30 grams of hydrofluoric acid, 270 grams of nitric acid and other acid components in deionized water to obtain 1000 grams of acidic solution; 3) prepare crystalline cerium acidic polishing solution: add in 1000 grams of acidic solution 20 g of additive; 4) The single crystal crucible was immersed in a polishing liquid for surface polishing at a polishing temperature of 13 ° C and a polishing time of 1 minute.

Example 6

The crystallization enamel is polished by the following steps: 1) preparing an additive for the crystalline phthalic acid polishing solution: 3 g of tartaric acid, 1 gram of polyvinyl alcohol and 2 g of sodium sulfate are dissolved in deionized water using 100 g of deionized water as a solvent. Additive; 2) Prepare acidic solution: dissolve 10 grams of hydrofluoric acid, 165 grams of nitric acid, 75 grams of sulfuric acid and other acid components in deionized water to obtain 1000 grams of acidic solution; 3) prepare crystalline cerium acidic polishing solution: at 1000 grams 40 g of the additive was added to the acidic solution; 4) the polycrystalline crucible was immersed in a polishing solution for surface polishing at a polishing temperature of 15 ° C and a polishing time of 45 seconds.

Example 7

The crystallization enamel is polished by the following steps: 1) preparing an additive for the crystalline phthalic acid polishing solution: 3 g of tartaric acid, 1 gram of polyvinyl alcohol and 2 g of sodium sulfate are dissolved in deionized water using 100 g of deionized water as a solvent. Additive; 2) Prepare acidic solution: dissolve 11 grams of hydrofluoric acid, 145.2 grams of nitric acid, 63.8 grams of sulfuric acid and other acid components in deionized water In the process, 1000 g of acidic solution is obtained; 3) preparing a crystalline bismuth acidic polishing liquid: adding 8 g of an additive to 1000 g of an acidic solution; 4) immersing the single crystal slab into a polishing liquid for surface polishing at a polishing temperature of 10 degrees Celsius. The polishing time is 1 minute.

However, the specific embodiments described above are merely used to exemplify the features and functions of the present invention, and are not intended to limit the scope of the present invention, and may be applied without departing from the spirit and scope of the present invention. Equivalent changes and modifications made to the disclosure of the present invention are still covered by the scope of the following claims.

Claims (8)

An additive for a crystalline cerium acidic polishing liquid, which comprises 2 to 5 parts by mass of tartaric acid, 0.5 to 2.0 parts by mass of polyvinyl alcohol, 1 to 3 parts by mass of sodium sulfate, and 100 parts by mass of water. An additive for a crystalline cerium-acidic polishing liquid according to claim 1, which comprises 2 to 3 parts by mass of tartaric acid, 0.5 to 1 part by mass of polyvinyl alcohol, 1 to 2 parts by mass of sodium sulfate, and 100 parts by mass of water. An additive for a crystalline cerium acidic polishing liquid according to claim 1 or 2, wherein the water is deionized water. A crystalline bismuth acidic polishing liquid prepared by the following steps: 1) dissolving an acid component in deionized water to prepare an acidic solution; the acid component comprises hydrofluoric acid and nitric acid; and the acid component of the acidic solution is total The mass percentage is 22 to 55%; 2) adding the additive according to any one of claims 1 to 3 to the acidic solution in the above step 1) to obtain a crystalline cerium acidic polishing liquid; The mass ratio of the additive to the acidic solution is 0.2 to 5:100. The crystalline bismuth acidic polishing liquid according to claim 4, wherein the total mass percentage of the acid component in the acidic solution is 27.5 to 45%; the mass ratio of the additive to the acidic solution is 1 to 3: 100. The crystalline bismuth acidic polishing liquid according to Item 4 or 5 of the patent application, wherein the content of the hydrofluoric acid in the acid component is 10 to 25%, and the mass percentage of the nitric acid is 75~. 90%. The crystalline bismuth acidic polishing liquid according to claim 4 or 5, wherein the acid component further comprises sulfuric acid; and the mass percentage of hydrofluoric acid in the acid component It is 2~5%, the mass percentage of nitric acid is 34~66%, and the mass percentage of sulfuric acid is 29~64%. A method for polishing a crystallization ruthenium, characterized in that a single crystal or a polycrystalline ruthenium sheet is immersed in a polishing liquid according to any one of claims 4 to 7 for polishing, and the temperature is controlled at 6 to 15 degrees Celsius. The time is controlled from 30 seconds to 3 minutes.