Endpoint detecting apparatus in a plasma etching system

摘要

An apparatus used for detecting the endpoint or described completion point of an etching process has a detection window, an optical cable, and a bracket for fixedly holding the detection window and the optical cable with respect to each other. The detection window protrudes outwardly from a wall of a reaction chamber. The optical cable transmits light generated during an etching process from the detection window to a detecting device separate from the detection chamber. The bracket is attached to the wall of the reaction chamber so as to configure a space between the bracket and the detection window. The configuration reduces the intensity of the electric field formed between the bracket and plasma in the reaction chamber.