INTERFEROMETRIC METHODS FOR DEVICE FABRICATION

摘要

INTERFEROMETRIC METHODS FOR DEVICE FABRICATION The invention involves new etch monitoring and thickness measurement techniques which are more accurate than previous techniques. In accordance with the invention, the etch depth of a substrate region undergoing etching is monitored, or the thickness of the region is measured by impinging the region with light and detecting the intensity of the reflected light. In contrast to the previous techniques, the incident light is chosen so that a substrate region underlying, and/or a patterned substrate region overlying, the substrate region of interest is substantially opaque to the incident light, which precludes the formation of signals unrelated to etch depth or thickness.