Gas Analysis in an r.f. Sputtering Plant

WHEN thin films of active metals are prepared by ion impact sputtering in the presence of plasma discharges, the deposits may be contaminated by gas impurities which react with condensing metal or form sputterable compounds on the target surface. It has been proposed that such gas sorption effects be used for reducing the level of impurities in the gas atmosphere in the deposition zone1–3; this technique has been termed “getter sputtering”. Holland and Priestland4 have theoretically analysed the gas kinetic conditions in a sputtering atmosphere. They showed that the impurities from desorption and in the inlet gas had relative partial pressures in the deposition atmosphere which depended on their respective rates of liberation and rate of removal by gettering and vacuum pumps.