Patent ID: 6618149
Filing Date: 2003-09-09
Classification: G01N

Abstract:
A method of determining the composition of a film stack, comprising:providing a library of optical characteristic traces, each of which correspond to a film stack combination comprised of a known combination of process layers formed above a known grating structure; providing a wafer having a film stack formed above said known grating structure; illuminating said film stack and said known grating structure; measuring light reflected off the film stack and said known grating structure to generate an optical characteristic trace for said film stack and said known grating structure; and determining the composition of the film stack formed above said known grating structure by correlating the generated optical characteristic trace for said film stack and said known grating structure to an optical characteristic trace from said library, the optical characteristic trace from said library having an associated film stack composition comprised of a known combination of process layers formed above said known grating structure.