Patent ID: 6825924
Filing Date: 2004-11-30
Classification: G01N

Abstract:
An apparatus capable of visually detecting the presence or absence of problems on the surface of a semiconductor substrate on which resist patterns are finely formed comprising:an illuminator comprising a single dual peak wavelength tube which is a light source emitting two different colors of lights, each said colored light having a narrow wavelength range, with a peak wavelength at a respective one of two complementary colors to each other, said light from said illuminator is capable of producing interference and diffraction but is not required to be coherent; supporting means for supporting a substrate having a surface on which predetermined patterns are finely formed, said surface being illuminated at a predetermined angle with said lights emanating from said illuminator, said surface functioning as a diffraction grating, and said lights being reflected and diffracted when said predetermined finely patterned surface is irradiated with said light; and determining means for determining whether said predetermined finely pattern surface on said substrate are deformed due to defocusing as a result of said light being diffracted by said finely patterned surface; and wherein when said surface does not contain abnormalities resulting from defocusing, said two diffracted lights are reflected and diffracted in the same direction from the entire surface of said substrate and the colors of the diffracted lights visually observed are substantially the same; and when there are abnormal portions on said finely patterned surface caused by defocusing, said lights diffracted by normal portions give one of the two complementary colors emitted by said source, while the lights diffracted by abnormal portions give the other of the complementary colors.