An Atomic Physics Model In a particle-in-cell code for stimulating plasma processing

We are developing self-consistent models for following the neutral particles existing in a plasma processing reactor. The neutral model is being made an integral part of the PIC-MCC plasma simulation code PDP1 which utilizes particle-in- cell techniques plus a Monte Carlo description of collisions of charged particles with neutrals. We shall compare the merits of treating the neutrals as fluids and/or as particles. As a specific example, we consider an oxygen RF discharge, including the energy-dependent processes of ionization, dissociation, recombination, detachment, and charge transfer. In addition to 0
₂
and electrons, we follow the evolution of O
⁺
₂
, O
⁺
, O
^-
, O
^-
₂
, O, and O
₃
. The relative concentrations of these products versus RF power and O
₂
pressure will be presented for the 1-100 mTorr range. We will discuss the modification of the dynamics of the discharge owing to the presence of substantial concentrations of negative ions. The atomic physics model can also be used for many other types of processing discharges, such as an ECH discharge.