In situ monitoring of plasma ignition step in capacitively coupled plasma systems

Abstract

For pulsed plasma to be used in an atomic layer process, the plasma ignition step should be carefully controlled to avoid lagged plasma ignition. We observed the ignition trend of Ar plasma using an optical plasma monitoring sensor in conjunction with plasma simulations. Under several process conditions, we used optical sensors to observe the dynamic responses of plasma glow discharge to reach a steady state; the elapsed times for the plasma ignition were found to vary depending on the process/equipment settings of pressure and power, and chuck distance. We also observed the stepwise plasma ignition behavior due to the conventional radio-frequency matching system during the short period of the plasma ignition. In the present paper, we report the in situ monitoring of plasma ignition and the reasoning related to the plasma generation environment in a capacitively coupled plasma system to be considered for plasma-assisted cyclic processes, including pulsed plasma systems.