Patent ID: 7436507

Claim:
An apparatus for inspecting a pattern, comprising: a light source which emits a light beam; a condenser which concentrates the light beam on the pattern to form a light spot; a scanning unit which scans the pattern using the light spot; a beam splitter which separates a light beam reflected from a position of the light spot on the pattern into a first reflected light beam on a first optical path and a second reflected light beam on a second optical path; a reflection detecting unit which receives the first reflected light beam and outputs a first light intensity signal; an astigmatism detecting unit which receives the second reflected light beam and outputs a second light intensity signal by an astigmatic method which second light intensity signal represents a distribution of a phase of the second reflected light beam; and an image processing unit which outputs an inspection image signal representing an inspection result of the pattern based on the first light intensity signal and the second light intensity signal.