Effects of Low-Frequency Source on a Dual-Frequency Capacitive Sheath near a Concave Electrode

A self-consistent two-dimensional (2D) collisionless fluid model is developed to sim- ulate the effects of the low-frequency (LF) power on a dual frequency (DF) capacitive sheath over an electrode with a cylindrical hole. In this paper, the time-averaged potential, electric field (E- field), ion density in the sheath, and ion energy distributions (IEDs) at the center of the cylindrical hole’s bottom are calculated and compared for different LF powers. The results show that the LF power is crucial for determining the sheath structure. As the LF power decreases, the potential drop decreases, the sheath becomes thinner, and the plasma molding effect seems to be more significant. The existence of a radial E-field near the sidewalls of a hole may cause a significant portion of ions to strike the sidewall and lead to the phenomenon of notching.