Reactive Magnetron Sputtering Control Based on an Analytical Condition of Stoichiometry

The conditions for stoichiometric thin film deposition by reactive magnetron sputtering include the existence of a given ratio between the flux of the sputtered metallic atoms and the flux of the reactive gas molecules on the surface of the substrate. To meet this condition, a relationship based on the Berg model is formulated between the partial pressure of the reactive gas, the target coverage, and the sputtering current density. Given that the target coverage can be estimated online from the sputtering voltage, it is possible to create a control structure where the reactive gas partial pressure is controlled to obtain stoichiometric thin film deposition. Simulation results are presented based on the dynamic model of the sputtering process.