Effect of Gas Flow on RF Plasmas

Abstract

Effects of gas flow on rf plasmas between parallel plates under plasma processing conditions are investigated using a Monte Carlo simulation (MCS) and a fluid model calculation. It has shown that the gas flow changes the ion density distribution in the bulk region of the rf plasma where the velocity of gas flow is faster than that of the ion diffusion motion. Comparison of the results of the MCS with those of the fluid model calculation has shown that the fluid model in which the velocity of gas flow is added to the drift and diffusion motion may be valid at a pressure above 1 Torr. Using the fluid model and Poisson's equation, self-consistent calculations of the argon and silane rf plasmas have been carried out. This indicates that the plasma structure including negative ions is sensitively changed by the gas flow.