Computational study of SF/sub 6//Ar plasma at low pressure etch regime

Summary form only given, as follows. Sulfur hexafluoride plasma discharges are presently used for a variety of plasma etch applications, ranging from MEMS (Bosch process) to semiconductor applications. SF/sub 6/ plasma is environmentally friendly (no PFCs) and can also be used for advanced dielectric and tungsten etch applications. In this work we developed computational model for table top, bell jar and HPEM generic reactors and validated it against experimental data for 50/50 SF/sub 6//Ar process recipe. In the model we do not account for surface etch reactions, but allow for the recombinations of ions and radicals at the walls. Constant gas temperature was assumed and the reaction mechanism followed. Industrial computer code CFD-PLASMA was utilized in the present studies. We simulated plasma regimes at pressures between 5 to 10 mtorr, absorbed powers between 100 to 1000 W at various SF/sub 6/ mass fractions. Generic results are presented. SF/sub 6/ plasma is strongly electronegative, require to account for generation and transport of negative ions. Thus it presents many computational challenges. Authors found that SF/sub 6/ gas is largely dissociated on SF/sub x/ fragments, degree of dissociation strongly increases with RF power. SF/sub 6/ almost completely dissociates in the center, while concentration of fluorine etching radicals peaks at the center of the plasma chamber.