Patent ID: 8792096
Filing Date: 2014-07-29
Classification: G01B,G01J,G01N,G03F

Abstract:
1. An inspection apparatus comprising: a radiation source configured to supply a radiation beam; an optical element configured to focus the radiation beam onto a substrate; a beam splitter system configured to split the radiation once reflected from the substrate into at least four components having different polarization orientations; a focusing system configured to focus the four components at different positions on a detector, the detector configured to detect simultaneously angle-resolved spectra of the four components of the radiation beam; a processor configured to use the angle-resolved spectra of the four components to determine a phase difference between polarization directions and a ratio between polarization direction amplitudes of the reflected radiation beam; and an iterative loop device configured to determine a refractive index, an absorption index, and a thickness of a resist layer on the substrate based on a difference between the determined phase difference and a modeled phase difference and based on a difference between the determined ratio and a modeled ratio.