Simultaneous, multiple channel measurements of semcionductor structures at different nominal azimuth angles

Abstract

Methods and systems for simultaneously performing optical based measurements of a semiconductor structure with multiple measurement channels each at different nominal azimuth angles are presented herein. In a further aspect, the measurement channels simultaneously collect measurement data resolved in wavelength, collection angle, polarization, or any combination thereof, at each nominal azimuth angle. In some embodiments, optical radiation generated by a shared illumination source is subdivided into multiple segments, each routed to a different measurement channel. In this manner, more of the optical output of the illumination source is simultaneously directed to the measurement spot of the semiconductor wafer. In some embodiments, multiple illumination pupil apertures are arranged to select different numerical apertures in the azimuth direction, the angle of incidence direction, or both, corresponding to each measurement channel. In another aspect, different measurement channels of a multi-angle measurement system perform measurements over a different spectral range.