Patent ID: 6570656
Filing Date: 2003-05-27
Classification: B23K

Abstract:
Apparatus comprising:a radiation source to flood a given surface area of a silicon wafer with a measured total value, eT, of radiation energy that is insufficient to damage or significantly heat said silicon wafer; a measurement system to measure the value of the fraction, er, of said flooding radiation energy that is specularly reflected from said given surface area, the value of any non-negligible fraction, es, of said flooding radiation energy which is scattered by said given surface area and the value of any non-negligible fraction, et, of said flooding radiation energy which is transmitted through said wafer; and a computer to derive an output indicative of the value, ea, of the fraction of said radiation energy flooding said given surface area which is absorbed by said silicon wafer in accordance with the equation ea=eTâˆ’(er+es+et).