Kinetic Simulation of Inductively Coupled Plasma Discharges for Reactive Ion Etching

Kinetic plasma simulations exercise particle-in-cell (PIC) and Monte Carlo (DSMC/MCC) methods to model the 6D phase space dynamics of plasma discharges; the reactive, collisional, low-temperature plasmas used in semiconductor manufacturing can be modeled with such methods. Though computationally more intensive, such simulations can provide many advantages over the more widely used fluid simulations, including detailed information about the Ion Energy/Angle Distribution Functions (IEDF/IADF) that are critical for plasma processing. In this presentation, kinetic PIC methods are used to model an inductively coupled plasma (ICP) discharge in a reactive ion etching chamber, wherein DC and RF voltage bias is applied to the substrate. We show how implicit methods can make these challenging simulations feasible. In addition, we demonstrate a method of providing constant power to the plasma which reduces the computational runtimes needed to reach steady-state. We explore how process parameters (neutral gas density, input power) and bias parameters (frequency, duty cycle, waveform shape) affect both the macroscopic discharge uniformity and the local IEDF and IADF at the wafer surface, as predicted by the model. As well, we discuss how these simulation results can be used as inputs for more detailed feature-scale simulations of etch processes.