A Mathematical Model for a Parallel Plate Plasma Etching Reactor

A mathematical model was formulated for predicting species concentration profiles and etch rate distribution in a parallel plate plasma reactor. Explicit account was taken of the ion-assisted component of etching by considering ion transport in the sheath. For the case of oxygen discharge, convective diffusion and chemical reactions of the etchant species were included as well as the electron density and energy variations in the bulk plasma. Important dimensionless system parameters were identified and their effect on etch rate, degree of etch anisotropy, and uniformity was examined. The model predictions were evaluated by comparison with experimental data on etch rate of polymer in an oxygen plasma as a function of pressure, power, and flow rate. For each, the model captured the salient features observed experimentally, although quantitative comparisons were not possible owing to the lack of accurate rate reaction kinetics data.