Resonance Type Electrical Variable Capacitor with Reduced Active Devices Loss for 13.56 MHz RF Plasma System

This paper introduces a parallel resonance type Electrical Variable Capacitor (EVC) designed to reduce the current stress of active devices for 13.56 MHz RF plasma system. As semiconductor requirements continue to advance, the demand for matching speed in semiconductor processes has been steadily increasing. However, the traditional Vacuum Variable Capacitor (VVC), which operates mechanically, has a very slow matching speed and is therefore unsuitable for processes requiring rapid matching times. To address this issue, the EVC was proposed. EVC operates electrically using switches, resulting in a significantly faster matching speed compared to VVC, approximately 1000 times faster. This makes EVC suitable for processes demanding fast matching systems. However, the conventional EVC circuits suffer from drawbacks such as a high cost, large volume. And it also has poor power efficiency due to have high current stress on active devices. This paper proposes new type of EVC circuit that address these issues. The proposed circuit use a minimal number of active components for variable operation, resulting in a compact and cost-effective EVC design. They also minimize current stress of active devices, making them more effective in high-power systems. Consequently, the proposed circuit can be effectively used in impedance matching networks for RF plasma systems that require high power.