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2005
Conference Paper
Title
Modeling of the plasma impedance in reactive magnetron sputtering for various target materials
Abstract
The simulation of the reactive sputtering process dynamics will have a major impact on the future development of in-line sputter coating technology in terms of model-based process control, precise adjustment of film composition and structure, as well as increased homogeneity and throughput. Besides the gas flow kinetics, the kinetics of sputtered neutrals and the surface chemisorption, the overall sputtering rate at a given power is mainly governed by the plasma impedance. Furthermore, the plasma impedance relates intrinsic process parameters like ion current density to external machine control variables such as total sputtering power. We present a heuristic model for the plasma impedance of a DC sputtering process considering: (I) the impact of the target oxidation state; (II) the gas composition on the secondary electron yield, and (III) the influecne of additional surfaces on the plasma density which is referred to as anode effect. Using this model we desribe target voltage hysteresis characteristics for the reactive TiOx and HfO2 processes obtained from a DC sputtering process in a lab coater.