Control of the ion flux and energy distribution of dual-frequency capacitive RF plasmas by the variation of the driving voltages

Abstract

Due to its advantages of spatial uniformity and ion energy control, a dual-frequency (DF) capacitive-coupled plasma is widely used in semiconductor etching and deposition processes. In low-pressure discharges, the mean free path of ions is longer than the sheath width, and the ion energy distribution function is sensitive to the driving voltage waveform. In this respect, it is necessary to use a particle-in-cell (PIC) simulation to observe ion movement according to the time-varying electric field in the sheath. This study uses a two-dimensional PIC simulation parallelized with a graphics processing unit to monitor the ion energy distribution and flux according to the DF voltage waveform. We suggested a method to control the ion energy through a phase-resolved ion energy distribution in the region, where the ion transit time is longer than the high-frequency period and shorter than the low-frequency period.