| CPC G01B 11/0641 (2013.01) [G01N 21/21 (2013.01); G01B 2210/56 (2013.01)] | 18 Claims |
|
1. A metrology apparatus to measure a thickness of a substrate, the metrology apparatus comprising:
an illumination source directed substantially orthogonally to an upper surface of the substrate;
a polarizer coupled between the illumination source and the substrate, the substrate to receive light from the illumination source after the light passes through the polarizer in a pre-determined state of polarization substantially orthogonally to the upper surface of the substrate, wherein the pre-determined state of polarization substantially matches an eigenmode of the substrate;
an optical detector to receive light returned from the substrate, the optical detector arranged substantially orthogonally to the upper surface of the substrate and between the illumination source and the substrate; and
an analyzer coupled between the substrate and the optical detector, the analyzer to determine an angle in a plane of polarization to which the light received from the substrate has been rotated due to optical properties of at least one of the substrate and films formed on the substrate.
|