Plasma diagnosis with Langmuir probe in the process of vacuum arc deposition

Abstract

This paper introduces some efforts to use the Langmuir probe as an in situ diagnostic tool in the process of VAD (vacuum arc deposition), i.e., to minimize the contamination on the probe and to discuss the validity of the probe theories. The characteristic curves are dealt with by Langmuir's thick-sheath model, and the plasma parameters (electron temperature kT/sub e/ and electron density n/sub 0/) are calculated from the combination of the I/sub e//sup 2//spl sim/V curves and LnI/sub e//spl sim/V curves. Plasma diagnoses are performed in the process of TiN film deposition, with different partial pressures of nitrogen, arc current and distances from the cathode. Nonelastic collisions in the VAD plasma are evaluated with the diagnostic results.