KLA Corporation
Multi-Wavelength Interferometry for Defect Classification

Abstract:

An inspection system may include a controller coupled to a differential interference contrast imaging tool for generating images of a sample based on illumination with two sheared illumination beams. The controller may determine a first defect-induced phase shift based on a first set of images of a defect on the sample with a first selected illumination spectrum and two or more selected induced phase differences between the two sheared illumination beams, determine a second defect-induced phase shift based a second set of images of the defect with a second selected illumination spectrum and two or more selected induced phase differences between the two sheared illumination beams, and classify the defect as a metal or a non-metal based on a comparison of the first phase shift to the second phase shift.