Plasma processing apparatus

Abstract

The invention provides a means for suppressing interference phenomenon on the surface of a sample to be processed that deteriorates the detection accuracy upon detecting the time variation of plasma conditions such as plasma space distribution or the processing status of the sample to be processed. A light scattering element (light transmitting means) 4 for diffusing and transmitting incident light and a convex lens 5 are arranged on a front stage of an optical fiber light receiving unit 6 connected to a photodetector 8 (photodetector such as a photodiode or a light quantity detector disposed via a spectroscope) disposed on an opposite side from a sample 2 to be processed as a means for observing the emission of plasma 1, so as to prevent the changes in light quantity accompanying the interference effect caused by the changes in thin film thickness on the surface of the sample 2 to be processed from reaching the photodetector 8.

Dependencies are inferred from the claim text.