Abrupt transitions in species number densities and plasma parameters in a CH3F/O2 inductively coupled plasma

Measured relative densities as a function of O2 addition in a CH3F/O2 inductively coupled plasma changed abruptly for H, O, and particularly F atoms (factor of 4) at 48% O2. A corresponding transition was observed in electron density, effective electron temperature, and gas temperature, as well as in C, CF, and CH optical emission. These abrupt transitions were attributed to the reactor wall reactivity, changing from a polymer-coated surface to a polymer-free surface and vice-versa, as the O2 content in the feed gas crossed 48%.