Particle-In-Cell simulations of inductive heating effects in radio-frequency capacitively coupled plasmas

High frequency (HF) capacitively coupled plasmas (CCPs) are ubiquitous, having several industrial applications, especially in the semiconductor industry. Inductive heating in CCPs driven at radio frequencies > 60 MHz play an important role and therefore understanding them is key to improve industrial applications. For this purpose kinetic research, using Particle-In-Cell (PIC) codes, offers great capabilities to study, and improve, industrial plasma processes that operate at atomic level. However, PIC codes commonly used for CCPs are electrostatic and thus cannot be used to simulate electromagnetically induced currents. In this study, we make use of the recently developed EPOCH-LTP, a 1D PIC code that incorporates an inductive current model, to simulate inductive heating effects in HF CCPs. We present results for an HF CCP (60 MHz) operated at 1 mTorr of argon, which show that inductive currents couple most of their power at the interface between the bulk plasma and the sheath. Furthermore, the simulation of a dual-frequency CCP, where a HF inductive current and a low-frequency (LF) voltage waveform are applied, have shown a synergy between the HF and LF waveforms that increase the inductive heating rates.