Application Note: Detection Of Hydrocarbon Radicals During Plasma Etching

T.A.R. Hansen and R. Engeln, Eindhoven University of Technology

Optical emission spectroscopy is used to study and monitor the plasma etching of hydrogenated amorphous carbon (a-C:H) thin films.

Thin layers of carbon impurities are found on optical components in both fusion reactors and lithography devices, thereby reducing the reflectivity of the mirrors (1). Plasma etching has been proposed as a method to remove these impurity layers without damaging the optics. Optical emission spectroscopy is a suitable tool for in situ monitoring of the etch process.