MODELING OF THE DEPOSITION OF STOICHIOMETRIC AL2O3 USING NONARCING DIRECT-CURRENT MAGNETRON SPUTTERING

dc sputter deposition of stoichiometric Al2O3 is usually difficult due to the formation of an oxidized layer on the target surface, which re duces the deposition rate drastically and causes charge buildup and ar cing at the target. To avoid this situation the arrival rate ratio O-2 /Al must be high enough at the substrate position that a stoichiometri c film can form but low enough at the target that a conducting target surface is maintained. We have utilized Monte Carlo simulations to est imate the flux distribution of sputtered particles for different geome tries. These results, supplemented by Bergs' standard steady state mod el for the reactive sputtering process, made it possible to predict th e composition at different surfaces in the processing chamber. Experim ental studies were carried out for several different target-to-substra te distances and a range of sputtering gas pressures. The results show that the process can be tailored to achieve stoichiometric Al2O3 at t he substrates while keeping the target in the metallic state. This is achieved by providing a high enough inert gas pressure or large enough target-to-substrate distance. Thick stoichiometric Al2O3 films were s uccessfully deposited at these conditions with low or no arcing during deposition. A considerable back-deposition of Al on to the noneroded part of the target keeping the surfaces conducting is the key factor f or the reduction of arcing. (C) 1998 American Vacuum Society.