Patent ID: 6504615
Filing Date: 2003-01-07
Classification: G01B,H01L

Abstract:
An optical apparatus for measuring profiles of a wafer having a pair of optical measuring systems located at positions facing to both surfaces of a wafer vertically supported at its edge and a thickness gauge with one or more sensors, each of said optical measuring systems comprising:a light emitter for discharging a measuring light beam; a collimator lens for rectifying said measuring light beam into a collimated beam; an optical flat for transmitting the collimated measuring beam; a light detector for receiving two measuring beams, one of which is reflected on a surface of said wafer and returned through said optical flat and said collimator lens, the other of which is reflected on a referential plane of said optical flat and returned through said collimator lens; and a computer for processing interference fringes which occurs between said two light beams, whereby profiles of main and backside surfaces of said wafer are calculated from said interference fringes corresponding to both surfaces of said wafer; and a real shape of said wafer is determined from said profiles of main and backside surfaces of said wafer in consultation with thickness values measured by said thickness gauge at a plurality of points of the wafer.