Impedance Matching Scheme of Electrical Variable Capacitors Using SiC MOSFET for 13.56MHz RF Plasma Systems

摘要

This paper introduces a novel method to reduce the capacitance variable time experienced by Vacuum Variable Capacitor (VVC) circuit of 320V/1kW/13.56MHz having a vacuum variable capacitor applied in impedance matching circuit of RF plasma system. The method replaces vacuum variable capacitor with a novel Electrical Variable Capacitor (EVC) employing a power electronics technology in order to reduce the capacitance variable time. The proposed idea successfully reduces the capacitance variable time in the VVC owing to fast switching action of power semiconductor switch and can be applied in the impedance matching circuit of high-power and high-frequency RF plasma system. The proposed circuit topology is effectively supported by experiment which has verified that the capacitance variable time of the EVC is maintained below 150us.