| 摘要 |
A silicon wafer formed with a circuit pattern is illuminated with light. Illuminating light diffracted by the silicon wafer is picked up by a CCD camera. An angle of incidence thetai of the illuminating light and an angle of diffraction thetad of the diffracted light is taken as a single set, parameters of the single set are changed at least once and a diffracted pattern from the silicon wafer is imaged two times. The parameters of the single set are decided so as to fulfill Px(sinthetad-sinthetai)=mlambd, where P is the pitch of the pattern, lambd is the wavelength of the illuminating light, and m is the diffraction order of the diffracted light. An image processing device then traces the larger of level signals for image signals obtained from the double-imaging to obtain an inspection signal. This makes changes in signal waveforms for flaws conspicuous.
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