A non-invasive RF sensor for plasma sheath monitoring: exercise in 300 mm transformer coupled plasma—reactive ion etching system

Abstract This study presents the application of a non-invasive plasma sheath monitoring sensor (PSMS) for tracking plasma characteristics and sheath dynamics in a 300 mm transformer coupled plasma-reactive ion etching (TCP-RIE) system. The amplitude measured by PSMS at 13.56 MHz exhibits strong correlations with the amount of source power and bias power in TCP-RIE system, highlighting its sensitivity to bias-driven plasma dynamics. Cross-validation with voltage/current ( VI ) probe measurements confirms the potential of PSMS in the monitoring sheath-related current variations. Pressure-dependent experiments reveal a critical transition near 20 mTorr, capturing the shift from collisionless to ohmic heating mechanisms. During E–H transitions, the PSMS amplitude decreases up to 400 W in E-mode and rises in H-mode, reflecting wall-related ion losses. This study presents that the suggested PSMS is versatile tool for non-invasive electrical plasma diagnostics, offering significant potential for optimizing plasma etching processes.