Multi-wavelength interferometry for defect classification

摘要

The inspection system may include a controller coupled to a differential interference contrast imaging tool for generating an image of a sample based on illumination with two split illumination beams. The controller includes a first defect-induced phase shift based on the image of the first set of defects on the sample, having a first selected illumination spectrum and at least two selected induced phase differences between the two split illumination beams. And determining a second defect induced phase shift based on the image of the second set of defects, having a second selected illumination spectrum and at least two selected induced phase differences between the two split illumination beams, and the second phase shift Defects can be classified as metallic or non-metal based on a comparison of the first phase shift to.