A novel sustaining mechanism in capacitively coupled radio frequency plasma in oxygen

This study presents numerical evidence regarding a new type of self-sustaining mechanism for capacitively-coupled-radiofrequency plasma utilizing a self-consistent relaxation continuum model. The regime's existence depends on an electron source, produced by a detachment reaction from negative ions with high density in the bulk plasma, under a system that the spatiotemporal total rate of electron attachment is greater than that of ionization. That is, a novel mechanism differs markedly from previous ones that radiofrequency plasmas are mainly sustained by the ionization multiplication of low density electrons in a sheath/plasma boundary. The consequences of this finding are discussed from both charge balance and reaction sequence balance in the bulk plasma at 13.56 MHz in oxygen.