Blasting of Affected Layer of Silicon Surface Sliced by Wire EDM

Polycrystalline ingot slicing by wire electric discharge machining (W-EDM) has been investigated to reduce kerf loss and wafer thickness. In order to use the sliced wafers for semiconductor devices, the modified surface layer induced by W-EDM must be removed. In this paper, we have demonstrated the elimination of the layer by abrasive blasting. Three types of abrasives were blasted at a speed of 100 m/s. The surfaces blasted with WA #1000 and GC #1000 were smoother than that sliced with a wire saw. The modified layer induced by W-EDM slicing could be removed by blasting with WA #1000 while scanning the surface three times. Solar cells were fabricated using wafers with the blasted surface with an efficiency of 15.2%, which was almost the same as that of cells fabricated from the wire-sliced wafers.