Apparatus for chemically etching a workpiece

摘要

Apparatus for chemically etching a Workpiece includes a chamber for receiving a process gas and having a pumping port for extracting exhaust gases, and a Workpiece support located in the chamber upstream of the pumping port. The chamber further includes a sub-chamber located upstream of the pumping port and downstream of the Workpiece support, and the sub-chamber includes a window and an excitation source, adjacent the window, for creating a plasma in a sample of the exhaust gases to create an optical emission which can be monitored through the window.