Plasma polymerization by magnetron glow discharge. III. Effect of magnetic field on sputtering characteristics of electrode materials

Abstract

The sputtering of metal in a magnetron glow discharge polymerization reactor system is investigated as a function of magnetic field. A pair of planar electrodes with circular arrangement of permanent magnets is used with a 10-kHz electric power source. The sputtering of metal from the electrode is investigated for argon (nonpolymer-forming gas) and methane (polymer-forming gas) plasmas. In the case of the argon plasma, the sputtering rate is measured by the rate of deposition of metal upon the surface of quartz crystal. In the case of the methane plasma, the sputtering rate is estimated from the polymer deposition rate and the metal content in the deposited polymer determined by electron spectroscopy for chemical analysis (ESCA). In both cases, no appreciable deposition of metal (Cu or Al used as the electrode) is observed if the maximum parallel component of the magnetic field (with respect to the electric field) is <100 G. The sputtering rate by argon plasma is much greater than methane plasma, and the rate increases with the magnetic field strength of a magnetron. The sputtering rate in a methane plasma is related to the deposition of polymer on the electrode surfaces.