Effect of azimuthally asymmetric reactor components on a parallel plate capacitively coupled plasma

Abstract

A three-dimensional fluid plasma model is used to investigate the impact of azimuthally asymmetric reactor components on spatial characteristics of parallel plate capacitively coupled plasmas. We consider three scenarios: high frequency (13.56 MHz) argon discharges with, separately, an off-axis circular plate surrounding the bottom electrode and an access port opening in the reactor sidewall, and a very high frequency (162 MHz) argon discharge with nonparallel electrodes. For the reactor with off-axis plate, both the Ar+ density and flux are strongly perturbed toward the direction of maximum grounded surface area, with azimuthal variation in ion flux up to 10%. Perturbations in Ar+ density due to the access port opening are localized to the region near the access port, and the impact on ion flux in the interelectrode region is minimal. Finally, the nonparallel electrodes result in a significant change in the location and shape of the Ar+ density profile, going from a center-peaked discharge with parallel electrodes to a flattened off-center profile when tilted less than 1° with a nominal 5 cm gap.