22 nm node wafer inspection using diffraction phase microscopy and image post-processing

We applied epi-illumination diffraction phase microscopy to measure the amplitude and phase of the scattered field from a SEMATECH 22 nm node intentional defect array (IDA) wafer. We used several imaging processing techniques to remove the wafer's underlying structure and reduce both the spatial and temporal noise and eliminate the system calibration error to produce stretched panoramic amplitude and phase images. From the stretched images, we detected defects down to 20 nm x 160 nm for a parallel bridge, 20 nm x 100 nm for perpendicular bridge, and 35 nm x 70 nm for an isolated dot.