Monocrystal silicon cleaning liquid and precleaning process

Abstract

The invention provides a monocrystal silicon cleaning liquid and a precleaning process. The monocrystal silicon cleaning liquid is characterized by comprising alkali, hydrogen peroxide and water. The precleaning process of the monocrystal silicon cleaning liquid is characterized by comprising the following concrete steps: blending the sodium hydroxide; hydrogen peroxide and water according to a certain proportion to prepare the monocrystal silicon cleaning liquid; heating to 60-80 DEG C; and cleaning the original silicon chips in the monocrystal silicon cleaning liquid. The invention has the advantages of favorable cleaning effect and stability, nonvolatility and lowered production cost.

Description

technical field [0001] The invention relates to a monocrystalline silicon cleaning solution and a pre-cleaning process, which are used for making monocrystalline silicon solar cells and belong to the technical field of solar cell production technology. Background technique [0002] At present, the production process of conventional monocrystalline silicon solar cells is as follows: surface pre-cleaning, texturizing to remove the damaged layer and form an anti-reflective textured structure, chemical cleaning and drying; the method of liquid source diffusion forms a uniform surface at each point on the surface of the silicon wafer. Doped PN junction; remove the peripheral PN junction and surface phosphosilicate glass formed during the diffusion process; deposit passivation and anti-reflection film on the surface; make the back electrode, back electric field and front electrode of the solar cell; sinter to form an ohmic contact, thus completing The entire battery production pro...

AI Technical Summary

Problems solved by technology

However, due to the high temperature and long time of the concentrated sulfuric acid process, sulfides will remain on the surface of the silicon wafer after SPM cleaning. These sulfides are difficult to remove with deionized water, and sulfuric acid mist and waste sulfuric acid will be generated during the process. , it is not optimistic about its operability and economy as the choice of single crystal texture

[0008]4. SOM cleaning solution, that is, sulfuric acid plus ozone is used, and ozone is used instead of hydrogen peroxide as an oxidant, but the oxygen content of ozone must be strictly controlled to avoid damage to the human respiratory organs. Influence, and the purification of ozone is not good, it is easy to introduce metal impurities

[0009]5. DHF cleaning, that is, using a certain concentration of hydrofluoric acid to remove the oxide on the surface of the silicon wafer, and the metal attached to the oxide is also dissolved in the cleaning solution Medium, but the removal effect on copper impurities is very poor, and it is easy to cause particle adsorption pollution

[0010]6. FPM cleaning solution, improved DHF cleaning, that is, mixing a certain concentration of hydrofluoric acid solution and hydrogen peroxide, can significantly reduce the adsorption of particles and metal impurities Contamination, but only limited to better removal of metal impurities and reduction of particle introduction

However, pure ultrasonic cleaning, coarse throwing and traditional APM cleaning processes have many shortcomings.

Ultrasound can only remove particles ≥ 0.4um. The disadvantages of coarse throwing have been mentioned above. Although APM cleaning fluid is more effective in controlling the color difference caused by organic matter and particle contamination in subsequent texturing, the use of APM cleaning fluid is not good for equipment. , The requirements for environment and process control are relatively high, ammonia water is relatively volatile, it is difficult to control process stability, the pungent smell is very strong, and the requirements for exhaust and drainage are very high, otherwise it will be harmful to the workshop environment and the health of employees