MEASURING THE SHAPE AND THICKNESS VARIATION OF A WAFER WITH HIGH SLOPES

摘要

In one embodiment, an interferometer system comprises two unequal path interferometers assembly to vary a wavelength of the collimated radiation beam, record interferograms formed by a plurality of surfaces, extract phases of each of the interferograms for each of the plurality of surfaces to produce multiple phase maps, determine each map from its corresponding interferogram, determine from each map local areas of interest with high slopes, tilt the wafer holder to allow measurement of the high slope areas of interest, and process measurement that covers the entire surface of an object including high slope areas.