Capacitively coupled radio-frequency hydrogen discharges: The role of kinetics Available to Purchase

This paper presents a systematic characterization of capacitively coupled radio-frequency hydrogen discharges, produced within a parallel plate cylindrical setup at different rf applied voltages $(Vrf=50–600V)$⁠, frequencies $(f=13.56–40.68MHz)$⁠, and pressures $(p=0.2–1torr)$⁠. A two-dimensional, time-dependent fluid model for charged particle transport is self-consistently solved coupled to a homogeneous kinetic model for hydrogen, including vibrationally excited molecular species and electronically excited atomic species. Numerical simulations are compared with experimental measurements of various plasma parameters. A good quantitative agreement is found between simulations and experiment for the coupled electrical power and the plasma potential. The model underestimates the values of the electron density, the self-bias potential, and the $H(n=1)$ atom density with respect to measurements, but agrees with experiment when predicting that all these parameters increase with either $Vrf$⁠, $f$⁠, or $p$⁠. The dissociation degree is about $10−3$ for the work conditions considered. Simulations adopt a wall recombination probability for H atoms that was experimentally measured, thus accounting for surface modification with discharge operating conditions. Results show the key role played by the atomic wall recombination mechanism in plasma description.