Pressure stability in reactive magnetron sputtering

Abstract

In high rate reactive magnetron sputtering the film deposition results in a substantial pumping rate of the reactive gas. When the depositing film is substoichiometric, the film's consumption of the reactive gas is limited by the arrival rate of that gas and so consumption increases with reactive gas partial pressure. When the film is saturated with gas, the reactive gas consumption is limited by the metal arrival rate. As the reactive gas pressure is increased reaction products form on the target (it is “poisoned”) and the metal flux falls, leading to a decreasing consumption of the reactive gas. At pressures where a stoichiometric film is formed the consumption of the reactive gas by the film will be falling. This can lead to an uncontrollable transition between a metallic and a poisoned target that makes the control of optimum deposition conditions difficult. We have investigated this instability and its causes and our results indicate various means of getting a stable deposition system.