Patent ID: 7333192

Claim:
A defect inspection apparatus, comprising: a stage that is caused to travel after a substrate to be inspected has been rested on the stage, the substrate having a circuit pattern formed thereon; an irradiation optical system that guides a beam flux emitted from a laser light source from a principal optical path to a first or second optical path, focuses the beam flux that has been guided to the first or second optical path into a slit-shaped beam, from a direction having a required inclination extending horizontally with respect to a major straight-line group of the circuit pattern and at a required angle of inclination to the surface of the substrate to be inspected, the slit-shaped beam being formed up by fluxes of light that are substantially parallel in a longitudinal direction of the slit-shaped beam, and irradiates the substrate with the slit-shaped beam such that the longitudinal direction is at a substantially right angle to a traveling direction of the stage; a detection optical system that uses an objective lens to converge reflected/scattered light obtained from contamination or defects present on the substrate that has been irradiated with the slit-shaped beam, and uses an image sensor to receive the reflected/scattered light that has been converged, convert the received light into a signal, and detect the signal; and an image processor that extracts, on the basis of the signal that has been detected by the image sensor of the detection optical system, a signal indicative of the defect such as contamination; wherein the irradiation optical system includes: a downward reflecting mirror that reflects downward the beam flux that has been guided to the first or second optical path; and a cylindrical lens and an inclined mirror each for focusing the beam flux that has been directed downward by the downward reflecting mirror onto the substrate to be inspected, as the slit-shaped beam, from the direction having the required inclination extending horizontally and at the required inclination angle.