Shallow angle interference process and apparatus for determining real-time etching rate

摘要

A process and apparatus for determining a real-time etching rate during a plasma mediated etching process. Real-time etching rate determination includes monitoring an interference pattern generated by a direct light beam and a reflected light beam from a wafer surface. A viewing angle for recording the interference pattern is nearly parallel to the wafer plane and at a fixed focal point on the layer to be removed. The direct light beam and reflected light beams are generated in situ during plasma processing.