Deep submicron 3D surface metrology for 300 mm wafer characterization using UV coherence microscopy
With the increase in diameter of Si wafers to 300 mm and above, and the decrease in minimum feature size to the deep submicron, there is a need to improve the lateral resolution of optical inspection techniques. Coherence microscopy normally uses a white light source in order to produce a narrow fringe envelope for use in surface relief measurement. In this paper we show that high intensity coherent UV light sources can also be used if a large numerical aperture objective is employed, in order to improve the lateral resolution. This forms the basis for a new metrology tool that could find many applications in the inspection of large Si wafers.
coherence microscopy white light interferometry non-destructive testing defect characterisation critical dimensions