Dynamic simulations of pulsed reactive sputtering processes

Abstract

In the reactive sputtering process numerous parameters interact in a complex and nonlinear way. Thus, if any parameter is changed during operation, it is not an easy matter to predict the response of the other involved parameters. The static behavior of the reactive sputtering process has previously been carefully investigated. However, studies of the time dependent behavior of this process are rare. It is important to study the dynamic behavior to gain a more complete understanding of the process. Furthermore, the increased use of pulsed power sources has set focus on the process dynamics. A model describing the time-dependent behavior of the pulsed reactive sputtering process is proposed in this work. The model suggests that the time to reach process equilibrium may vary substantially depending on the process history. This memory effect has been experimentally verified. Finally, the simulations clearly point out that for high repetition frequencies (>1 kHz) of the pulsed direct current (dc) reactive sputtering process there will be no time-dependent variations of the chemical compositions either at the target surface or at the growing film at the substrates. At these high frequencies the chemistry of the process will act identical as to the continuous dc reactive sputtering process having the average pulsed dc power supplied to the target.