Patent ID: 7540971

Claim:
A plasma etch process for etching high aspect ratio openings in a dielectric film on a workpiece in a reactor having a ceiling electrode overlying the workpiece and an electrostatic chuck supporting the workpiece, comprising: injecting a first polymerizing etch process gas through at least a first selected one of plural concentric zones of gas injection orifices in the ceiling electrode; evacuating gas from said reactor through a pumping annulus surrounding an edge of the workpiece; coupling RF power into the reactor so as to etch high aspect ratio openings in the dielectric film with etch species derived from the etch process gas while depositing a polymer derived from the etch process gas onto the workpiece; and injecting oxygen or nitrogen gas through at least some respective ones of the plural concentric gas injection zones of the ceiling electrode at respective polymer management gas flow rates, apportioning said respective polymer management gas flow rates in accordance with a first distribution, and increasing over time said respective polymer management gas flow rates at respective polymer management gas flow rates of increase during the etch process; injecting an inert diluent gas through at least some of the plural concentric gas injection zones of the ceiling electrode at respective diluent gas flow rates, and apportioning said respective diluent gas flow rates in accordance with a second distribution different from said first distribution.