Ascertaining crystallographic orientation of semiconductor wafer - determining deflection of reflected light beam at both natural split planes in horizontal and vertical directions

The semiconductor wafer (100) is split at both its natural splitting planes (150, 160) in such a way a part of the wafer surface (130) and at least a part of a large flat (110) remain undamaged. The wafer is laid on a measuring table surface with the large flat admitting a vertical projection. In a registering process light from a scope is directed in a set direction onto the split planes. The reflected light beam is registered in horizontal and vertical planes. The crystallographic orientation of the surface of the wafer and the fault orientation of the large flat are determined from the deflections. USE/ADVANTAGE - Preparing wafer surface for best possible epitaxy or ion implantation processing in simple way at necessary level of precision.