Simulation study on Electrode-Based Suppression of Standing Wave Effects in Capacitively Coupled Plasma

In capacitively coupled plasma (CCP) etching systems, plasma uniformity is a critical factor that directly influences the spatial distribution of the etch rate across the wafer surface. As the electrode size increases and the system operates in the very high frequency (VHF) regime, standing wave effects become increasingly significant. These standing waves induce spatial variations in the local RF voltage amplitude, leading to distortions in the plasma potential and electric field distributions.

Such distortions lead to nonuniform ion energy and flux distributions, thereby degrading the etch rate uniformity and ultimately impacting process yield. Therefore, controlling standing wave-induced asymmetries is essential for achieving reliable and uniform plasma processing.

In this study, we propose a mitigation strategy that utilizes a specially designed electrode configuration to suppress standing wave effects. A two-dimensional axisymmetric plasma simulation was conducted to reproduce the standing wave behavior in a CCP chamber, and to evaluate the effectiveness of the proposed electrode structure. The simulation results demonstrate that the optimized electrode layout significantly improves the radial uniformity of plasma potential and electric field, contributing to enhanced etch rate uniformity. This study establishes the feasibility of electrode-based suppression of standing wave effects as a practical strategy for improving plasma uniformity in VHF CCP systems.