A Laser Interferometer System to Monitor Dry Etching of Patterned Silicon

Abstract

A laser interferometer system to monitor plasma etch rate, and to control etched depth of isolation areas in silicon for oxide isolated bipolar devices, is reported. The etching process is stopped as soon as the desired etched depth is achieved. The accuracy of the system is 4–6%, depending on the masking material. It is found that this method of laser interferometry can be particularly useful in process development for observations in real time of changes in etch rate.