PURPOSE: To properly detect a flaw irrespective of the properties on the surface of a wafer.
CONSTITUTION: A flaw inspection apparatus is provided with a holding stage device 11 for a wafer 1, with an inspection-light irradiation device 20 by which the wafer is irradiated with inspection light 21, with a scattered-light detector 34 which detects scattered light 31 from the inspection light in the wafer and with a flaw judgment device 40 which judges a flaw on the basis of its inspection result. In the flaw inspection apparatus, an offset processing circuit 39 which lowers an offset value so as to correspond to the reflection factor, the absorption factor and the like of the wafer 1 is interposed and installed in a signal processing circuit for the scattered-light detector 34. The offset value of a DC component is reduced by the offset processing circuit 38, and a scattered-light signal waveform in which the offset value of the output signal waveform of the scattered-light detector 34 is high, in which its scattered-light signal wavefom is saturated by the dynamic range of the detector 34 and which corresponds to a flaw signal buried in its component becomes tangible. As a result, the flaw can be deteted irrespective of the properties on the surface of the wafer 1.
MIYAMOTO YOSHIYUKI
NAOHARA HIROSHI
HITACHI ELECTR ENG
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