Measurement of thick films and high aspect ratio structures

Abstract

The system includes a light source configured to emit light along an illumination path; a projection optical assembly disposed in the illumination path; a target disposed in the illumination path and configured to reflect the light along a collection path; a collection optical assembly disposed in the collection path; a detector disposed in the collection path and configured to detect the light reflected from the target and generate an output signal based on the detected light; and a processor in electronic communication with the detector and configured to generate a measurement of the target based on the output signal. The projection optical assembly defines a first numerical aperture at the target and the collection optical assembly defines a second numerical aperture at the target, and the first numerical aperture is slightly larger than the second numerical aperture for measurements of thick films and high aspect ratio structures.

Dependencies are inferred from the claim text.