Dynamics of Crack Propagation during Silicon Spalling

Spalling has been proposed as a promising kerfless technique for slicing thin silicon wafers and thus double the yield of a silicon ingot. The main challenge of spalling is to control the roughness and thickness variation of the spalled wafers, that can be as high as 100% of the wafer thickness. We have shown that these thickness variations are largely influenced by the interaction of the crack front with reflected waves at the edges and the stress field applied at the crack tip. In this paper, we provide the necessary information to fully understand the origin of the surface roughness caused by the interaction of the reflected waves with the crack front. These new insights of the crack dynamics can pave the way to attain full control on the surface quality of the spalled wafer.