Patent ID: 6967490

Claim:
An apparatus for electrical characterization of a semiconductor wafer during semiconductor processing, said apparatus comprising: a head assembly comprising a surface photovoltage electrode; a conveyer for conveying said wafer such that a surface of said wafer is substantially parallel to said surface photovoltage electrode of said head assembly; an inversion layer for forming an inversion layer at a surface of said wafer; a light source generating light having a wavelength and modulated at a frequency and wherein at least a portion of said wafer is exposed to said light; a detector comprising said photovoltage electrode for detecting a photovoltage induced at the surface of said wafer in response to said light; a processor in electrical communication with said detector for calculating a depletion width from said photovoltage induced at the surface of said wafer; and said processor in electrical communication with said detector for calculating an electrical property from said depletion width.