Auto-Bias Electrical Variable Capacitor of Reduced Active Component Count and Voltage Stress for 13.56 MHz RF Plasma Process

This article introduces a novel electrical variable capacitor (EVC) circuit for use in the impedance matching circuits employed by 13.56 MHz RF plasma systems. The proposed design employs a turn-on/off using bias current and voltage condition technology, reducing the number of active components necessary for the EVC to operate. Experiments comparing the proposed EVC to state-of-the-art alternatives confirmed that the proposed design successfully operated with the reduced number of active components. Proposed EVC of automatic bias action by the power semiconductor switch may improve the impedance matching circuits used in high-power and high-frequency RF plasma system.