Patent ID: 8066895

Claim:
A method for processing a substrate, comprising: positioning the substrate on a substrate support disposed in a plasma chamber, wherein a showerhead having a bottom surface is disposed in the plasma chamber such that the bottom surface is disposed above the substrate support, and wherein the bottom surface of the showerhead comprises an inner distribution zone having a plurality of holes directed to a central region of the substrate support, a middle distribution zone having a plurality of holes directed to a middle region of the substrate support located radially outwards to the central region, and an edge distribution zone having a plurality of holes directed to a region near an edge of the substrate support, such that each of the distribution zones is isolated from the other distribution zones; flowing a first processing gas comprising an etching gas through the inner distribution zone towards a top surface of the substrate; flowing a second processing gas comprising a passivating gas through the edge distribution zone towards an edge region of the substrate; and striking a plasma of the processing gases in the plasma chamber.