Patent ID: 7019844
Filing Date: 2006-03-28
Classification: G01B,G01N

Abstract:
1. A method of determining a parameter of interest during fabrication of a patterned substrate, comprising: illuminating at least a portion of the patterned substrate with a normal incident light beam; obtaining a measured net reflectance spectrum of the portion of the patterned substrate from a normal reflected light beam; calculating a modeled net reflectance spectrum of the portion of the patterned substrate as a weighted incoherent sum of reflectances from n≧1 different regions constituting the portion of the patterned substrate, wherein the reflectance of each of the n different regions is a weighted coherent sum of reflected fields from k≧1 laterally-distinct areas constituting the region; and determining a set of parameters that provides a close match between the measured net reflectance spectrum and the modeled net reflectance spectrum.