EFFECTS OF ATOMIC CHLORINE WALL RECOMBINATION - COMPARISON OF A PLASMA CHEMISTRY MODEL WITH EXPERIMENT

Results from a plasma chemistry model provide predictions of spatially and temporally averaged plasma properties. Application of the model t o chlorine-etch process conditions, typical of a high plasma-density t ransformer coupled plasma reactor, provides plasma composition depende nce on reactor operating parameter such as power and pressure. Model r esults also show the dependence of species concentrations on the atomi c-chlorine recombination rate at reactor walls. Comparison of model pr edictions to measured composition trends as determined by Langmuir pro be, actinometry, and ion-energy analysis reveals a critical wall-recom bination probability of about 0.1 for chlorine atoms on a chlorinated anodized-aluminum surface. Ar or above this critical value, the model reproduces the experimentally observed trends, while employing a recom bination probability below this value results in predictions that are inconsistent with the data. The model determines gas-phase and surface -species compositions in plasma-etch reactors through the solution of species, mass. electron-energy, and surface-site conservation equation s. The use of well mixed reactor approximations reduces the computatio nal expense of detailed kinetics calculations and allows investigation into the dependence of plasma chemistry on uncertain kinetic paramete rs. The dominance of surface reaction rates in determining plasma prop erties is expected to be equally important in more complex two-dimensi onal inductively coupled plasma models due to the highly diffuse natur e of these low-pressure reactors. (C) 1995 American Vacuum Society.