PIC/MCC simulations of the effects of a radio-frequency bias on inductively coupled plasmas

The growing need for precision plasma processing has made radio frequency (RF) wafer biasing crucial for plasma parameter control. We developed a two-dimensional Particle-in-Cell/Monte Carlo Collision model capable of simulating inductively coupled plasma (ICP) discharges, incorporating both electrode geometry and RF bias circuit coupling. The model was validated against experimental data from unbiased argon ICP discharges in a Gaseous Electronics Conference reference cell. With an increasing RF bias voltage within a certain range, the plasma density decreases nonlinearly and the electron energy probability function shifts toward low-energy populations, while the ion energy and angular distribution function at the wafer electrode transition from a single-peak structure to a double-peak structure with reduced angular dispersion. Further, equivalent impedance analysis reveals that the energy delivered to the plasma at the fundamental driving frequency is converted into energy generated in the plasma at higher harmonic frequencies through nonlinear mechanisms.