工业双频电容耦合射频放电的空间和相位分辨等离子体参数

The dynamics of high energetic electrons (
11.7 eV) in a modified industrial
confined dual-frequency capacitively coupled RF discharge (Exelan, Lam
Research Inc.), operated at 1.937MHz and 27.118 MHz, is investigated by
means of phase resolved optical emission spectroscopy. Operating in a He–O2
plasma with small rare gas admixtures the emission is measured, with
one-dimensional spatial resolution along the discharge axis. Both the low and
high frequency RF cycle are resolved. The diagnostic is based on time
dependent measurements of the population densities of specifically chosen
excited rare gas states. A time dependent model, based on rate equations,
describes the dynamics of the population densities of these levels. Based on
this model and the comparison of the excitation of various rare gas states, with
different excitation thresholds, time and space resolved electron temperature,
propagation velocity and qualitative electron density as well as electron energy
distribution functions are determined. This information leads to a better
understanding of the dual-frequency sheath dynamics and shows, that separate
control of ion energy and electron density is limited.