Patent ID: 7180584
Filing Date: 2007-02-20
Classification: G01N

Abstract:
1. A method of inspecting a specimen having an optically-transparent film thereon, comprising: emitting light containing a plurality of wavelengths from a light source; illuminating the specimen with a selected wavelength or wavelengths of the light through a lens; detecting through the lens with a sensor, an image of a pattern on the specimen as illuminated by the selected wavelength or wavelengths of the light, and outputting from the sensor, a signal concerning a detected image; and processing the signal outputted from the sensor and obtaining information of defects of the pattern; wherein, in the illuminating, selection of the selected wavelength or wavelengths of the light is made so as to substantially prevent optical interference of lights reflected from the specimen to form the image, where the optical interference is affected by a variation of thickness of the optically-transparent film formed on the specimen.