Laser wafering

A new technique for the laser wafering of semiconductors is presented using sub surface laser engraving. In the laser wafering process, a high intensity laser is used to form sub-surface etch pits or defects at multiple depths in an ingot. This allows a rapid, controllable approach to the formation of wafers with thickness ranging from below 10 microns to over 100 microns. Laser wafering provides a way to cut a a brick of silicon into multiple wafers with minimal kerf loss and the possibility to dramatically lower the cost of silicon solar cell production. The techniques relies on the principle that many materials, including silicon and other semiconductors, have a non-linear absorption co-efficient with intensity, such that sub-band gap light is absorbed above a given intensity. This allows a high intensity laser to be focused at an arbitrary point below the surface, and allowing absorption of the high intensity light only at the focal point.