Deposition and redeposition in magnetrons

Abstract

The deposition probability and spatial distribution of atoms sputtered from a magnetron cathode have been semiquantitatively measured for a variety of chamber pressures for Cu and A1 cathodes in Ne, Ar, and Kr gases. In this experiment, a large substrate plane was mounted parallel to a planar cathode. The cathode to sample distance was varied from 5 to 14.5 cm. Deposited films were measured on the sample plane, the area to the side of the cathode, and areas on the cathode itself Deposition probabilities were calculated by comparison to the starting number of atoms. The deposition probability increased with decreasing pressure, throw distance, gas mass, and increasing cathode atom mass or discharge power. The redistribution back onto the cathode correlated inversely roughly with the deposition onto the sample plane. In the worst cases, sputtered atoms were more likely to redeposit onto the cathode surface than deposit on the sample plane. A clear trend was observed correlating gas scattering effects with local changes in the gas density due to thermalization effects in the background gas. © 1988 American Vacuum Society