Patent ID: 8383002

Claim:
A method of performing a plasma etch process on a workpiece surface of a workpiece comprising a surface material to be etched, comprising: placing the workpiece on a workpiece support in a chamber of the plasma reactor; introducing through a ceiling gas disperser a first process gas comprising an etchant species capable of causing etching of said surface material in a plasma; generating a plasma in said chamber by coupling RF power into said chamber; controlling etch rate distribution across said workpiece surface by adjusting flow rate of said first process gas through said ceiling gas disperser; reducing etch rate at an edge periphery of said workpiece surface relative to etch rate across a remainder of said workpiece surface by injecting a polymerizing gas through a workpiece support gas disperser provided on said workpiece support and facing said edge periphery, said workpiece support gas disperser defining a polymerizing gas injection pattern directed toward said edge periphery of said workpiece surface and confined generally to said edge periphery; providing a slit injector comprising a thin opening extending circumferentially around said edge periphery of said workpiece surface and extending from a lower boundary coplanar with said workpiece surface to an upper boundary above a plane of said workpiece surface; and wherein said injecting a polymerizing as comprises flowing said polymerizing gas from a gas supply passage supported on said workpiece support and ejecting said polymerizing as through said slit injector along a radial direction parallel to said workpiece surface.