Assistance to Determine the Stability State of a Reactive Sputtering Process Based on the Analytical Solution of the Classical Berg Model

In this study, we propose simple analytical formulas for reactive sputtering technology, which can be used to assist in the selection of appropriate sputtering parameters during the deposition of thin films. Radio frequency (RF) sputtered alumina (Al2O3) was used to evaluate the results. Layers with O/Al ratios ranging from 24/76 to 54/73 were deposited. Following effective deposition, the equations of the Berg model describing the process were studied. The achieved stoichiometry and the associated technological parameters are of critical importance for the analysis of the equations; consequently, this established the primary guiding principle when selecting the analytical approximations. A straightforward graph of the processing parameters (pumping speed, partial pressure) has been constructed, with the objective of avoiding the hysteresis that is an inherent feature of the reactive sputtering process. In addition, we have extended the classical Berg model to examine how the biased substrate can influence deposition. It was found that applying a substrate bias can decrease target coverage, while it does not alter substrate coverage.