Enhanced plasma generation in capacitively coupled plasma using a parallel inductor

Abstract

Plasma generation efficiency in a capacitively coupled plasma (CCP) at high densities or high conductivity tends to be lower due to low plasma resistance. An inductor is installed to a powered electrode in parallel to improve plasma generation efficiency at higher density in the CCP. To reduce the power loss in a system, a parallel resonance is used between the capacitance of the CCP and the inductance of the parallel inductor. When parallel resonance occurs, the impedance of the chamber, including the plasma, increases. Therefore, the current flowing in the system is expected to decrease. At the resonance, the current in the system significantly decreases, and the voltages and currents at the powered electrode significantly increase. This phenomenon indicates that the system power loss is decreased, and the power absorbed by the plasma is increased. As a result, the ion density and the voltage at the powered electrode are increased up to 66% and 25% at the parallel resonance condition, respectively. To understand these increases, a circuit model for the plasma and the parallel inductor is suggested which shows good agreement with the experimental results. This method can be applied to the CCP for improving plasma generation.