Patent ID: 6331888
Filing Date: 2001-12-18
Classification: G01N

Abstract:
An apparatus for wafer surface inspection comprising:a light source;an irradiating optical system for throwing a light beam from said light source on the surface of an object of inspection;a light receiving optical system for receiving a reflected light beam from said object of inspection;a photosensing portion for sensing the reflected light beam received by said light receiving optical system;a signal processing portion for processing the signal from said photosensing portion;a displacement portion for providing relative displacement of the surface of the object of inspection and scanning the inspecting light beam from the light source to the surface of the object of inspection through the irradiating optical system; anda peak detecting circuit for:sensing a point where the scattered light signal by a foreign-matter exceeds a threshold signal or threshold signal level while the inspecting light beam is scanned in a predetermined direction as a start point;sensing a point where the foreign-matter scattered signal thereafter falls below the threshold signal or threshold signal level as an end point; andsensing a point where the foreign-matter scattered signal was at its maximum level between the start point and the end point as a peak; andwherein the signal processing portion evaluates sensed data to determine existence of foreign matter on the surface of the object of inspection.