Patent Document ID: 9518916
Application ID: 14511810
Patent Status: 1

Claim One:
1. A method of determining a structure or process parameter value of a target of interest on a semiconductor wafer, the method comprising: defining a plurality of collection patterns for a spatial light beam controller positioned at a pupil image plane of a metrology tool; for each collection pattern, collecting a signal from a sensor of the metrology tool, wherein each collected signal represents a combination of a plurality of signals that the spatial light beam controller samples, using each collection pattern, from a pupil image of the target of interest, wherein the collection patterns are selected so that the pupil image is reconstructable based on the collection patterns and their corresponding collection signals; analyzing the collected signal for each of the collection patterns to determine a structure or process parameter value for the target of interest; obtaining a representative set of pupil images from a plurality of test structures that were fabricated or simulated with known process variations; extracting basis images for a plurality of possible collection patterns that are most related to the known process variations from a large set, of basis images that are generated for the representative set of pupil images; and using the extracted basis images to define the collection patterns for the spatial light beam controller.