Focused beam scatterometry for deep subwavelength metrology

Abstract

It is known that far-field scattered light requires <i>a priori</i> sample information in order to reconstruct nm-scale information such as is required in semiconductor metrology. We describe an approach to scatterometry that uses unconventional polarization states in the pupil of a high NA objective lens. We call this focused beam scatterometry; we will discuss the sensitivity limits to this approach and how it relates to micro-ellipsometry as well as low-NA scatterometry.