Abstract: This paper studies the surface of monocrystalline silicon cut by wire-cut electrical discharge machining (WEDM). The formation mechanism and damage forms of the damaged layer of monocrystalline silicon cut by WEDM are studied by observation and analysis of the surface morphology and anisotropic etching. The results show that there are four kinds of damage forms of the damaged layer: thermal damage, thermal stress damage, combined effects of heat and stress damage, and electrolytic and electrochemical corrosion damage. Thermal damage will produce polysilicon or amorphous silicon on the surface of the silicon; thermal stress damage will make the silicon surface crack; combined effects of heat and stress damage will produce small holes on the suface of the silicon, and the greater the discharge power density is, the more holes there are on the silicon surface; electrolytic and electrochemical reaction will cause accelerated corrosion of the damaged area and the area where contaminants are gathered.

Key words: wirecut eletrical discharge machining, monocrystalline silicon, damaged layer, damage form, formation mechanism