A three-dimensional finite element fluid model and a corresponding simulation tool have been developed for studying azimuthal asymmetries and their effect on etch uniformity in inductively coupled plasma ͑ICP͒ reactors. For silicon etching with chlorine in an ICP reactor with a planar coil, four different cases were examined: ͑a͒ uniform power deposition without a focus ring, ͑b͒ uniform power deposition with a focus ring, ͑c͒ nonuniform power deposition without a focus ring, and ͑d͒ nonuniform power deposition with a focus ring. When etching is ion driven, the power deposition profile is most important for etch uniformity, because azimuthal nonuniformities in the ion production rate can persist even down to the wafer level. For uniform power deposition, the effect of asymmetric pumping becomes more important. A focus ring can play an important role in alleviating azimuthal nonuniformities, especially in the nonuniform power deposition cases. Gas inlets pointing parallel to the wafer plane introduce only local disturbances in the species profiles.

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