Temporal and Spatial evolution of the EEP$f$ and the Discharge Mechanism in a Microwave Surface-Wave Plasma

Surface-wave plasma excited at 2.45GHz by the radial line slot antenna (RLSA) has been used for plasma CVD, film-growth and more recently, etching applications. Its noted performance advantage is thought to be due to a low $T_{e}$ quiescent plasma in the wafer-region. 2-D particle-in-cell (PIC) numerical experiments are used to elucidate its energy-coupling mechanism in sustaining plasma ionization. Temporal evolution from power onset through ignition to steady state reveals E-field amplification under the \textit{$\omega $}$_{P}$=\textit{$\omega $} resonance. Consequent Langmuir waves serve to complete the ignition process through Landau damping on the fast electrons. Approach toward steady state results from a continuation of the \textit{$\omega $}$_{P}$=\textit{$\omega $} resonance or heating by the surface wave's ponderomotive force depending on the density. The steady-state EEP$f$ near the dielectric plate exhibits a beam-like component which is verified by probe measurements. Spatially resolved probe measurements away from the plate reveal an EEP$f$ which asymptotes toward a Maxwellian with $T_{e}\sim $1eV near the wafer-region. Microwave opaqueness of the over-dense plasma and electron-neutral collisions contribute to the demise of the beam-component of the EEP$f$ making it a genuine decoupled plasma.