Abstract
The dependence of the etch depth of a contact hole or circular via on the diameter of the hole opening is derived for a simple model which includes the effect of the bombarding ions and the neutral radicals on the etching. The ion etch rate at the center of the contact hole is proportional to the ion energy flux and the neutral etch rate is proportional to the neutral flux expression for molecular flow in a pipe. The total etch rate expression is found by Langmuir kinetics. The linear experimental relation for the etch depth versus the inverse diameter holds in this model for etching in the near ion flux-limited regime. The dependence of the etch depth and average etch rate on the etch time is given for this model.
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