Model and Verification of a Plasma Etching Reactor with a Switched-Mode Power Converter

For reaching a high selectivity in plasma etching, it is required to precisely control the plasma ion energy. This can be realized by applying a tailored pulse-shape voltage waveform to the reactor table. Recent research has shown that switched-mode power converters can be used to generate this kind of waveform, with the benefit of increased efficiency compared to the traditional linear amplifier. However, the equivalent electric circuit model of the plasma etching reactor is required in order to do circuit simulation and make an optimized electronic design of such switched-mode power converters. Although several circuit models of the reactor have been presented in previous research, they can not be directly adopted in tailored pulse-shape biasing.In this paper, a modified equivalent electric circuit model of the reactor is proposed. The plasma behaviour is modelled using the equivalent electric circuit and it is suitable for electric circuit simulation together with the power converter. Both the electrical waveforms and the normalized ion energy distribution can be obtained from the simulation, which are in line with the experimental results.