Patent ID: 7431859

Claim:
A plasma etch process for etching a workpiece in a process region of a reactor having a ceiling electrode overlying the process region with plural concentric gas injection zones, comprising: injecting process gases with different compositions of chemical species through different ones of said gas injection zones to establish a distribution of chemical species among said plural gas injection zones, said injecting comprising controlling respective gas flow rates to respective ones of said zones individually for each individual one of the following gases: (a) a fluorine-rich polymerizing etch gas that promotes a high etch rate, (b) a carbon-rich polymerizing etch gas that promotes a high polymer deposition rate, (c) a polymer management gas that retards polymer deposition rate and (d) an inert diluent gas that reduces etch profile tapering; and distributing said processes gases among said plural gas injection zones so that (a) said fluorine-rich etch process gas has the highest flow rate over zones of the workpiece tending to have the lowest etch rate, (b) said carbon-rich etch process gas has the highest flow rate over zones of the workpiece tending to have the highest etch rate, (c) said polymer management gas has the highest flow rate over zones of the workpiece tending to have the highest tendency for etch stop, (d) said inert diluent gas has the highest flow rate over zones of the workpiece tending to have the greatest etch profile tapering.