Research and scheme of solar silicon wafer cleaning agent

In the photovoltaic industry, in the production process of solar wafers, people need to clean the wafers before they can produce qualified products. Because the surface pollutant composition of solar silicon is more complex, mainly including grease, rosin, epoxy resin, polyethylene glycol and other organic matter, as well as dust and other particle pollution and metal ions, they are usually cleaned in the way of chemical cleaning and physical adsorption method on the surface of the silicon or the oxide film of the silicon. These impurities seriously affect the performance and yield of the battery. The requirements of silicon cleaning are to remove all kinds of impurities without destroying the silicon.

For silicon cleaning technology, its development process can be roughly divided into the following four stages:

In the first stage, the initial chemical and mechanical polishing is established, but due to improper use and treatment, it often re-precipitates other impurities on the metal surface and causes re-pollution of metal impurities.

The second stage, from 1961 to 1971, used the original RCA-1 cleaning agent, the development of which is a monument to the history of cleaning technology;

The third stage, from 1972 to 1989, the work in this stage was mainly based on the chemical principle of RCA cleaning, in-depth research and analysis of the application and influencing factors, and continuous improvement of RCA cleaning technology;

The fourth stage, from 1990 to the present, focuses on the research of the mechanism and dynamics of solution cleaning and the development of new cleaning technologies.

The purpose of this experiment is to develop an alkaline, no organic solvent, no irritating odor, low cost water based special cleaning agent, the cleaning effect of which is required to be equal to or better than the traditional cleaning method of solar silicon wafers. Our cleaning agent formula, with non-ionic surfactants and anionic surfactants as the main components, the cleaning method has the advantages of easy operation, low cost, non-toxic, no corrosion to the skin, no harm to the human body, no pollution to the environment.

1、Formula and main raw materials: fatty alcohol polyoxyethylene ether; 6501 nonylphenol polyoxyethylene ether; Sodium dodecyl benzene sulfonate LAS; Triethanolamine oleic acid soap; Sodium tripolyphosphate; NaOH, these are all industrial products. Disodium ethylenediamine tetraacetic acid (C.P).

2、Formulation evaluation：

1)The cleaning agent formula is alkaline, the cleaning rate is more than 99%, the surface of the cleaning object will not remain insoluble matter, will not cause new pollution to the cleaning matter, will not affect the quality of the product, the surface of the silicon chip after cleaning is clean.

2)The cleaning agent can be used for ultrasonic cleaning at normal temperature, with mild cleaning conditions, no special requirements for temperature, pressure, mechanical energy, etc., and lower energy consumption for enterprises.

3)The return rate of the cleaning agent after cleaning is very low, only 10% of the traditional cleaning process, the process is simple, easy to operate, to meet the requirements of environmental protection.