Patent ID: 8139232
Filing Date: 2012-03-20
Classification: G01B,G01N

Abstract:
1. An ellipsometric metrology tool for optically measuring characteristics of a substrate comprising: at least one light source adapted to output a beam of incident light; a first optical element for focusing the incident light onto a metrology site of the substrate having a periodic structure formed thereon at a plurality of incident angles and at a plurality of azimuthal angles, an optical axis of the first optical element being inclined at an oblique angle with respect to a plane of the substrate; a second optical element for directing reflected light reflected from the metrology site to a detector, the detector output being at least partially correlated to a polarization state of the incident light, a phase shift of the reflected light, at least one of the plurality of incident angles, and at least one of the plurality of azimuthal angles of the incident light with respect to the metrology site.