Patent ID: 7532317

Claim:
A scatterometry method, comprising: entering grating structure parameters into a computer; calculating a diffraction profile based on the grating structure parameters over a first range of incident light values; incrementally changing one or more of the grating structure parameters; repeatedly calculating a diffraction profile and incrementally changing one or more of the grating structure parameters to calculate additional diffraction profiles based on the changed grating structure parameters over the first range of incident light values; identifying a characteristic region of the calculated diffraction profiles wherein a change in an incrementally increasing grating structure parameter value causes a change exceeding a threshold value among the diffraction profiles; storing the characteristic regions of the calculated diffraction profiles in a library; performing scatterometry on a sample substrate and generating scattering signatures over a second range of incident light values; comparing the scattering signatures with the calculated diffraction profiles in the library; and identifying a calculated diffraction profile that matches the scattering signature to a selected level of similarity.