Abstract: A method for improving the efficiency of a plasma process such as a sputter process. A low partial pressure of a gas such as oxygen liberated from a substrate in a reaction chamber is maintained. The low partial pressure may be maintained by providing a plasma gas having a mass that is about equal to or greater than the liberated gas to the reaction chamber at a rate so that the steady state ratio of the plasma gas to the liberated gas is at least 1. The plasma gas is preferably argon. Alternatively a low partial pressure may be maintained by providing an in situ getter or a reactive, condensation or selective pump in the chamber. The method is applicable to a sputter etch or a sputter deposition process.