In Situ Analyses of Surface-Layer Composition of CxNy Thin Films Using Methods Based on Penning Ionization Processes—Introductory Investigations

Abstract

Carbon nitride materials have received much attention due to their excellent tribological, mechanical and optical properties. It was found that these qualities depend on the N/C ratio; therefore, the possibility to control it in situ in the sputtered film is of high importance. The plasma-electron spectroscopy method based on the Penning ionization process analysis is developed here to control this ratio in CNx films produced by plasma-sputtering in a pulsed-periodic regime of glow discharge. The electron energy distribution function is determined by the means of a single Langmuir probe placed in the center of the discharge tube. The mixture N2:CH4:He was used in the process of sputtering. The applied concentrations of CH4 varied in the range of 2–8%, and He concentration was 80–90%. The gas pressure in the discharge tube used for sputtering varied between 1 and 10 Torr, and the current was between 10 and 50 mA. It was shown that the proposed method enables the extraction of information on the composition of the surface layer of the investigated film and the development of an on-line inspection, without extracting the film from the sputtering chamber.