JPS6459928A - Inspection of surface condition - Google Patents

Abstract

PURPOSE:To increase greatly the accuracy of separation of a foreign substance and a circuit pattern, which exist on a substrate, to reduce troubles due to the sensitivity difference, a change in the sensitivity and so on of a light-receiving part and to contrive the cutdown of cost by a method wherein the substrate and an optical system are tilted relatively by a constant angle and are inspected twice. CONSTITUTION:A substrate 5 is returned by an angle of beta1 in a counterclockwise rotation to the incident direction 01 and 02 of a laser beam and moreover, is rotated by an angle of beta2 in a counterclockwise rotation similarly. In short, the substrate is rotated by an angle of (beta1+beta2) in a counterclockwise rotation and is inspected two times. Whereupon, diffracted light from a patterns 10, which makes an angle of beta1 to the longitudinal and lateral directions of the substrate 5, is not received because the light goes emitting to a direction that makes an angle of (beta1+beta2) to the light-receiving direction 01 and 02. Moreover, if a scanning direction is changed (The longitudinal and literal directions of the substrate are not included.) and an inspection is conducted twice, the diffracted light is not received if a thing detected in the first inspection is the pattern and if the thing is a foreign substance, the diffracted light is received by reason of its isotropic scattering property. Thereby, a definite decision of whether the thing is the pattern or the foreign substance can be performed.