Dependence of optimal conditions for abundant O(1D) surface flux on the source gas ratio and pressure of O2/Ar inductively coupled plasmas

초록

We present a 2D axisymmetric fluid model consistently coupled with a 0D Boltzmann-solver electron energy distribution function and a detailed Ar/O-2 chemistry set that includes electron-impact dissociation and excitation, energy-transfer (quenching) reactions of O(D-1), ion neutral exchange, and wall recombination. Across 3-100 mTorr and 10%-90% O-2 mixing ratio, we quantify the spatial distributions of O(P-3) and O(D-1) and the O(D-1) flux at the target boundary. The O(D-1) density and flux are primarily set by dissociative excitation of O-2 (e + O-2(X-3 Sigma(-)(g)) -> e + O(D-1) + O(P-3)), electron-impact excitation of atomic oxygen (e + O(P-3) -> e + O(D-1)), and energy transfer from O(D-1) to O-2 (O-2 + O(D-1) -> O(P-3) + O-2(b(1)Sigma(+)(g))). In addition, the O(D-1) density and flux are modulated by (i) pressure-driven transport limitation (reduced diffusion and shorter mean free path), (ii) composition-dependent shifts between net production and O-2 quenching, and (iii) enhanced thermal speed and thermal diffusion at low O-2 due to elevated gas temperature. Consequently, high pressure and high O-2 density confine production to the under-coil inductive skin region and suppress the target-boundary flux, whereas at low O-2 density the weaker quenching and higher gas temperature partially offset transport-limited attenuation. These results indicate that predictive control of the O(D-1) density and flux requires a joint treatment of transport, explicit energy-transfer quenching, and thermal-diffusion effects within a detailed reaction set.

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