Low pressure r.f. plasma jet—a new tool for surface processing

Abstract

An extremely reactive r.f. plasma jet system (RPJ) operating at gas pressures in the range 10–10 4 Pa is described. The RPJ works as a hollow-cathode supplied by d.c. bias through the space-charge sheath surrounding the r.f. electrode provided by an appropriate gas nozzle. A simplified model of plasma jet generation is presented. Properties and parameters of the supersonically flowing and decaying plasma in the jet channel were measured by Langmuir probes and by optical emission spectroscopy. Radial and axial profiles of basic micro parameters of the jet channel are presented. The effect of the frequency of the r.f. generator (13.56 and 27.12 MHz) on the plasma jet properties is shown. The chemical activity of the RPJ was demonstrated previously by very high-rate deposition of films ( e.g Si-N and a-Si : H) as well as by the rapid etching of silicon in a fluorine-based RPJ, both at rates of about 0.1 mm min −1. The first results of depositions of hard crystalline carbon films, Si-C and diamond films are presented with respect to process parameters. Conditions for the generation of an arc-type discharge in the RPJ system for reactive sputtering and etching are briefly characterized. As an example, nitrogen sputtering of the titanium jet nozzle for Ti-N film deposition into narrow tubes (diameter less than 10 mm) is described.