Yield enhancement for the surface of solar-cell silicon wafers with electromechanical micromachining

Effective yield enhancement for the surface of silicon wafers of solar cells was developed using electrochemical micromachining and a design disc-form tool as a precision recycling module for Si3N4 thin-film microstructures and epoxy film. The low yields of epoxy films and Si3N4 thin-film deposition are important issues in semiconductor production. The current approach uses strong acid and grinding and may cause both damage to the physical structure of silicon wafers and pollution. Electrochemical micromachining allows the removal of the surface Si3N4 layer and epoxy film from the silicon wafers and may lead to the development of a mass production system for recycling defective or discarded silicon wafers of solar cells. A high feed rate of the silicon wafers of solar cells combined with enough electric power produces fast machining performance during etching. High rotational speed of the disc-form tool leads to high dreg discharge mobility and a good etching effect. A small height or a small bitter end radius of the anode corresponds to a high removal rate of the Si3N4 and epoxy. A small surface area of the cathode also corresponds to a high removal rate. (C) 2010 Elsevier Ltd. All rights reserved.