Patent ID: 6342704
Filing Date: 2002-01-29
Classification: G01N

Abstract:
A method and apparatus of detecting the presence of nitride residue on the surface of a semiconductor wafer after said wafer has been etched, comprising the steps of:(A) subjecting said wafer surface to light; (B) measuring the magnitude of light reflected from said wafer surface having a wavelength within a range of wavelengths characterizing the color of said nitride residue; and, (C) comparing the magnitude measured in step (B) with a reference value, the result of the comparison performed in step (C) indicating the presence or absence of said nitride residue on said wafer surface, wherein step A is performed by directing a beam of light generally onto the periphery of said wafer surface, and said directing is performed by delivering first and second beams of light respectively onto generally diametrically opposite sides of said wafer surface.