CN112144122A

CN112144122A - Texturing additive and texturing liquid suitable for large-size monocrystalline silicon wafers and application

Info

Publication number: CN112144122A
Application number: CN202011131120.7A
Authority: CN
Inventors: 周树伟; 张丽娟; 陈培良
Original assignee: Changzhou Shichuang Energy Co Ltd
Current assignee: Changzhou Shichuang Energy Co Ltd
Priority date: 2020-10-21
Filing date: 2020-10-21
Publication date: 2020-12-29
Also published as: WO2022083362A1

Abstract

The invention discloses a texturing additive, a texturing solution and application suitable for large-size monocrystalline silicon wafers, wherein the texturing additive comprises the following components in percentage by mass: 0.5-10% of main nucleating agent, 0.2-5% of supplementary nucleating agent, 0.01-0.1% of branched dispersing agent, 0.05-0.5% of defoaming agent and the balance of water. The texturing solution comprises the texturing additive and an alkali solution. The texturing additive is applied to texturing of large-size monocrystalline silicon wafers. The invention thoroughly solves the problem of non-uniformity in the wafer after the texturing of the large-size silicon wafer; the texturing reflectivity is low, and the texturing time is short; the difference of the reflectivity of the silicon wafer after texturing is reduced to 0.10-0.15%, which is superior to that of a commercial texturing additive.

Description

Texturing additive and texturing liquid suitable for large-size monocrystalline silicon wafers and application

Technical Field

The invention relates to a texturing additive, a texturing solution and application, in particular to a texturing additive, a texturing solution and application suitable for large-size monocrystalline silicon wafers.

Background

Since the semiconductor industry has grown in scale earlier than the photovoltaic industry, and silicon photovoltaic wafers are very similar in technology to semiconductor silicon wafers in itself, silicon photovoltaic wafers derived from the semiconductor silicon wafer size standard have undergone three changes in size from small to large over the years, from 0.75 inches in the last 60 years to 12 inches today and 18 inches to the next generation. Before 2012, the silicon wafer size increased from 100mm, 125mm to 156 mm; 2012 to 2018, the silicon wafer size was changed from M0 (edge distance 156 mm) to M1 (edge distance 156.75 mm), M2 (edge distance 156.75 mm); to date in 2018, the silicon wafer sizes have revolutionized to larger G1 (edge distance 158.75mm), M6 (edge distance 166 mm), and M12 (edge distance 210 mm).

The driving force for the increase in silicon die size is fundamentally the amortization cost. In order to respond to the requirements of the national flat price internet policy, reduce the electricity consumption cost and improve the industry competitiveness, the rapid development of the photovoltaic technology in recent years has the key role played by the continuous increase of the sizes of silicon wafers and battery plates. The size is increased to obtain higher assembly power, and meanwhile, the productivity of a manufacturing end is improved, and the manufacturing cost is reduced. The large size has become a must path for the development of the photovoltaic industry.

In the process of manufacturing the cell, the influence of the increase of the size of the silicon wafer is not only photovoltaic equipment, but also auxiliary materials such as additives, silver paste, screen printing plates and the like, wherein the texturing additives are the most direct part in influence. The texturing aims to generate texture on the surface of a high-reflectivity primary silicon wafer so as to achieve the light trapping effect, thereby improving the sunlight absorption rate and further improving the photoelectric conversion efficiency of the cell. Most of additives used in the wet texturing process are developed and obtained on the basis of M2 silicon wafers at present, and the main problem of a customer using a large-size silicon wafer at the texturing end, namely the phenomenon of uneven reflectivity in a chip after texturing, cannot be solved only by some improvements. Originally, on an M2 silicon wafer, the difference of the reflectivity in the wafer after texturing is smaller to be about 0.2-0.3%, but as the size of the silicon wafer is increased to be M6 and M12, the difference of the reflectivity of the upper position and the lower position of the same silicon wafer after texturing can reach 0.5-0.6% and even can be 1%, and the difference has certain influence on the efficiency of the battery wafer.

Disclosure of Invention

The purpose of the invention is as follows: the invention provides a texturing additive suitable for large-size silicon wafers, which can thoroughly solve the problem of non-uniformity in a wafer after texturing of the large-size silicon wafer.

The second purpose of the invention is to provide a texturing solution based on the texturing additive.

A third object of the invention is to propose the use based on the above-mentioned texturing additive.

The technical scheme is as follows: the invention adopts the following technical scheme:

a texturing additive suitable for large-size monocrystalline silicon wafers comprises the following components in percentage by mass: 0.5-10% of main nucleating agent, 0.2-5% of supplementary nucleating agent, 0.01-0.1% of branched dispersing agent, 0.05-0.5% of defoaming agent and the balance of water.

Preferably, the main nucleating agent is hydrolyzed polyacrylonitrile sodium salt, and the supplementary nucleating agent is polyamino acid.

Further preferably, the polyamino acid is selected from one or more of polyglutamic acid, polyaspartic acid, polylysine, polydiaminobutanoic acid, and polydiaminopropionic acid.

Preferably, the branched dispersant is a branched polyethyleneimine.

Preferably, the defoaming agent is selected from one or more of dodecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride and octadecyl trimethyl ammonium chloride.

Preferably, the water is deionized water.

The invention also provides a texturing solution for single crystal texturing, which comprises the texturing additive and an alkali solution, wherein the mass ratio of the texturing additive to the alkali solution is 0.25-2.5: 100, and the alkali solution is an inorganic alkali aqueous solution.

Preferably, the alkali solution is 1-3 wt% of sodium hydroxide or potassium hydroxide aqueous solution.

The invention also provides an application of the texturing additive, wherein the texturing additive is applied to texturing of large-size monocrystalline silicon wafers, and specifically comprises the following steps:

(1) adding 0.5-10% of main nucleating agent, 0.2-5% of supplementary nucleating agent, 0.01-0.1% of branched dispersing agent and 0.05-0.5% of defoaming agent into the balance of water in percentage by mass, and uniformly mixing to prepare a texturing additive;

(2) adding the texturing additive prepared in the step (1) into an alkaline solution in proportion, and uniformly mixing to prepare a texturing solution; wherein the mass ratio of the texturing additive to the aqueous alkali is 0.25-2.5: 100, and the aqueous alkali is an aqueous solution of inorganic alkali;

(3) and (3) immersing the large-size monocrystalline silicon wafer into the texturing solution prepared in the step (2) for surface texturing to obtain a textured silicon wafer.

In the step (1), the main nucleating agent is hydrolyzed polyacrylonitrile sodium salt, and the supplementary nucleating agent is polyamino acid; the branched dispersant is branched polyethyleneimine; the defoaming agent is selected from one or more of dodecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride and octadecyl trimethyl ammonium chloride; the water is deionized water.

Further, the polyamino acid is selected from one or more of polyglutamic acid, polyaspartic acid, polylysine, polydiaminobutyric acid and polydiaminopropionic acid.

Further, the mass percent content of the main nucleating agent is preferably 2.5-5%, the mass percent content of the supplementary nucleating agent is preferably 0.7-1%, the mass percent content of the branched dispersing agent is preferably 0.05-0.1%, and the mass percent content of the defoaming agent is preferably 0.1-0.2%.

Wherein in the step (2), the alkali solution is 1-3 wt% of sodium hydroxide or potassium hydroxide aqueous solution.

Wherein in the step (3), the surface texturing temperature is 75-85 ℃ and the time is 5-8 min.

Further, the temperature of the surface texturing is preferably 80 ℃.

In the additive for making wool, the main nucleating agent hydrolyzed polyacrylonitrile sodium salt is an anionic polymer obtained by alkaline hydrolysis of polyacrylonitrile waste, and the molecular chain contains-CONH₂Strong polar groups such as-COO-CN and the like form strong hydrogen bond action with Si-H bonds on the surface of the silicon wafer, can be well adsorbed on the surface of the silicon wafer to generate abundant nucleation points, and thus has good wool outlet performance; the molecular chain of the supplementary nucleating agent polyamino acid has carboxyl and amino groups with strong polarity simultaneously, so that the supplementary nucleating agent polyamino acid is better combined with the surface of a silicon wafer further, and more stable nucleation points are generated, so that the supplementary down forming effect is achieved after the supplementary nucleating agent polyamino acid is combined with the main nucleating agent hydrolyzed polyacrylonitrile sodium salt for compounding, the supplementary down forming effect and the main nucleating agent hydrolyzed polyacrylonitrile sodium salt have good down forming performance, and the down forming density and the down forming window are improved.

The branched polyethyleneimine has a long molecular chain due to larger molecular weight, a special branched structure and a large number of amino groups thereon, has excellent dispersibility, and is commonly used as a dispersing agent, a stability reinforcing agent, a surfactant, a chelating agent and the like, so that two compound nucleating agents can form uniform and stable nucleation points in a texturing system, and a texturing agent can be more fully and uniformly distributed on the surface of a silicon wafer, so that the pyramid still has good uniformity after growth, which cannot be compared with a conventional dispersing agent.

The defoaming agent is used for improving the appearance problem caused by different bubble removal rates of the upper part and the lower part of the large-size silicon chip.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages:

(1) the problem of non-uniformity in the wafer after the texturing of the large-size silicon wafer is thoroughly solved;

(2) the texturing reflectivity is low, and the texturing time is short;

(3) the difference of the reflectivity of the silicon wafer after texturing is reduced to 0.10-0.15%, which is superior to that of the commercial texturing additive.

Detailed Description

The technical solution of the present invention will be further described with reference to the following examples.

Example 1

(1) Mixing 2.5% of hydrolyzed polyacrylonitrile sodium salt, 0.5% of polyaspartic acid, 0.5% of poly-diaminobutyric acid, 0.05% of branched polyethyleneimine, 0.2% of dodecyl trimethyl ammonium chloride and 96.25% of deionized water according to the mass percentage, and uniformly stirring to prepare a texturing additive;

(2) adding sodium hydroxide and deionized water into a texturing groove body to prepare 1wt% of aqueous alkali, adding the texturing additive obtained in the step (1), and uniformly stirring to prepare a texturing solution, wherein the mass ratio of the texturing additive to the aqueous alkali is 0.7: 100;

(3) and (3) putting the monocrystalline silicon wafer with the size of M6 into the texturing solution prepared in the step (2) for texturing, and carrying out texturing reaction for 7min at the temperature of 80 ℃ to obtain the textured silicon wafer.

Example 2

(2) adding sodium hydroxide and deionized water into a texturing groove body to prepare 1.2wt% of aqueous alkali, adding the texturing additive obtained in the step (1), and uniformly stirring to prepare a texturing solution, wherein the mass ratio of the texturing additive to the aqueous alkali is 0.7: 100;

(3) and (3) putting the monocrystalline silicon wafer with the size of M6 into the texturing solution prepared in the step (2) for texturing, and carrying out texturing reaction at the temperature of 80 ℃ for 5min to obtain the textured silicon wafer.

Example 3

(1) Mixing 5% of hydrolyzed polyacrylonitrile sodium salt, 0.5% of polyaspartic acid, 0.2% of polyglutamic acid, 0.1% of branched polyethyleneimine, 0.1% of dodecyl trimethyl ammonium chloride and 94.15% of deionized water according to mass percentage, and uniformly stirring to prepare a texturing additive;

Comparative example

Adding sodium hydroxide and deionized water into a texturing tank body to prepare 1wt% of aqueous alkali, adding a commercial texturing additive (product model: TS50 produced by Yongzhou Shishao energy resource Co., Ltd.) according to the mass ratio of the additive to the aqueous alkali of 0.7:100, and uniformly stirring to prepare a texturing solution; putting the monocrystalline silicon wafer with the size of M6 into a texturing solution for texturing, and carrying out texturing reaction for 7min at the temperature of 80 ℃ to obtain the textured silicon wafer.

The silicon wafers after texturing prepared in examples 1-3 and comparative example were tested for reflectivity respectively, where the reflectivity of the upper and lower positions corresponding to the front and back sides of the silicon wafer at a distance of 3cm from the edge was tested by using an NXT Helios-rc reflectivity tester, and the average reflectivity of the front and back points was calculated respectively, and the specific results are shown in table one.

TABLE average reflectance of textured silicon wafers from examples 1-3 and comparative examples

Group of	Upper position of silicon wafer	Lower position of silicon wafer
			Example 1	10.56%	10.41%
Example 2	10.88%	10.79%
			Example 3	10.47%	10.35%
Comparative example	12.03%	11.48%

As can be seen from the table I, when the texturing additive is applied to texturing of large-size monocrystalline silicon wafers, the reflectivity difference of the upper part and the lower part of the textured silicon wafers is controlled to be 0.10-0.15%, and the in-chip reflectivity difference of the conventional texturing additive is as high as 0.55%, which shows that the texturing additive achieves good in-chip reflectivity uniformity, the average reflectivity of the textured silicon wafers is reduced by 10% compared with that of the conventional additive by the texturing additive, and the conversion efficiency of a battery is further improved while the texturing uniformity is ensured.

Claims

1. A texturing additive suitable for large-size monocrystalline silicon wafers is characterized in that: the composite material comprises the following components in percentage by mass: 0.5-10% of main nucleating agent, 0.2-5% of supplementary nucleating agent, 0.01-0.1% of branched dispersing agent, 0.05-0.5% of defoaming agent and the balance of water.

2. The additive according to claim 1, wherein the additive is selected from the group consisting of: the main nucleating agent is hydrolyzed polyacrylonitrile sodium salt, and the supplementary nucleating agent is polyamino acid.

3. The additive according to claim 2, wherein the additive is selected from the group consisting of: the polyamino acid is selected from one or more of polyglutamic acid, polyaspartic acid, polylysine, polydiaminobutyric acid and polydiaminopropionic acid.

4. The additive according to claim 1, wherein the additive is selected from the group consisting of: the branched dispersant is branched polyethyleneimine.

5. The additive according to claim 1, wherein the additive is selected from the group consisting of: the defoaming agent is selected from one or more of dodecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride and octadecyl trimethyl ammonium chloride.

6. The additive according to claim 1, wherein the additive is selected from the group consisting of: the water is deionized water.

7. A texturing liquid for single crystal texturing is characterized in that: the additive comprises the wool making additive and the alkaline solution according to any one of claims 1 to 6, the mass ratio of the wool making additive to the alkaline solution is 0.25-2.5: 100, and the alkaline solution is an aqueous solution of inorganic alkali.

8. The texturing solution for single crystal texturing according to claim 7, characterized in that: the alkali solution is 1-3 wt% of sodium hydroxide or potassium hydroxide aqueous solution.

9. The application of the texturing additive suitable for the large-size monocrystalline silicon piece is characterized in that the texturing additive is applied to texturing of the large-size monocrystalline silicon piece, and specifically comprises the following steps:

10. Use of a texturing additive according to claim 9, characterized in that:

in the step (1), the main nucleating agent is hydrolyzed polyacrylonitrile sodium salt, and the supplementary nucleating agent is polyamino acid; the branched dispersant is branched polyethyleneimine; the defoaming agent is selected from one or more of dodecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride and octadecyl trimethyl ammonium chloride; the water is deionized water;

in the step (2), the alkali solution is 1-3 wt% of sodium hydroxide or potassium hydroxide aqueous solution;

in the step (3), the surface texturing temperature is 75-85 ℃ and the time is 5-8 min.