Wire Electrical Discharge Slicing of Solar-Grade Silicon

A method of slicing solar-grade silicon into thin wafers is greatly demanded because of the rapid increase in the production volume of photovoltaic cells. Wire electrical discharge machining seems to be a suitable slicing method because it is a noncontact process that hardly cracks wafers. However, solar-grade silicon is not so highly conductive that it is difficult to slice it by wire electrical discharge machining. In this paper, we propose a new machining power supply suitable for slicing solar-grade silicon, which causes minimum damage to the machined surface. We also show that photovoltaic cells made from the wafers sliced by wire electrical dischage machining are comparable to conventional cells. We conclude that wire electrical discharge machining can be one of the practical methods of slicing solar-grade silicon.