Three-Dimensional Simulation of Microwave Propagation in an Electron Cyclotron Resonance Plasma

Abstract

Electron cyclotron resonance (ECR) plasmas which can generate high density under low pressure are widely used in plasma processing applications such as etching for semiconductor and thin-film deposition. In these applications, ECR plasmas are required to be uniform over a large-diameter wafer. For this problem, the analysis of microwave propagation in the plasma is important because the microwaves can have significant influence on the formation of the spatial profiles of the plasma. In this paper, we present a three-dimensional simulation of microwave propagation in an inhomogeneous ECR plasma using the finite-difference time-domain (FDTD) method. As a result, it was found that the wave propagation was sensitive to the spatial profile of the plasma density, and much different from that in an isotropic dielectric medium. In addition, it was found that a three-dimensional model reproduced the experimental results measured by interferometry much better than a one-dimensional model.