Plasma conditions for the deposition of wear-resistant carbon-coatings

Abstract

The properties of sputter and microwave-ECR plasmas have been investigated with a plasma emission monitor (PEM) in the range between 280 and 820 run with various resolutions. Additional Langmuir probe measurements of the sputter plasma were performed to determine the spatial variation of electron density and temperature. Using helium as an additional measuring gas, the electron temperature has been determined by comparing the intensities of an argon and a helium emission line. The concentration of atomic hydrogen and CH radicals can be determined by actinometry. A comparison between the two types of plasmas shows similar electron temperature dependencies on the plasma power, the argon partial pressure and the acetylene partial pressure. The electron temperatures determined from PEM and Langmuir probe measurements correlate very well. When the microwave ECR plasma is used at the same time as the sputter plasma the electron temperature in the sputter plasma is reduced because of the charged particle current flowing out of the ECR plasma. The electron temperature in the ECR plasma varies only slightly when the sputter plasma is switched on but the concentration of atomic hydrogen increases because of the additional conversion of the acetylene on the target surface.