Patent ID: 7780866

Claim:
A method of processing a workpiece in a plasma reactor chamber, the chamber including a ceiling and a side wall, a workpiece support pedestal with a workpiece support surface within the chamber, a pumping annulus with a pumping port between said pedestal and said side wall, and a plasma processing region provided between said pedestal and said ceiling , said method comprising: constraining plasma in said chamber away from said floor of said pumping annulus, said constraining including providing an annular baffle extending from said pedestal into said pumping annulus and constricting a flow of gas and plasma through said pumping annulus; compensating for asymmetry of gas flow attributable to said pumping port, said compensating including providing a gas flow equalizer below said baffle having an eccentrically shaped gas flow opening surrounding said pedestal; modifying radial distribution of plasma ion density over said pedestal, said modifying including providing a magnetic plasma steering field having an edge high plasma ion density distribution tendency; and locating said baffle at a distance below said workpiece support surface, said distance providing an edge low plasma ion density distribution tendency that compensates said edge high plasma ion density distribution tendency of said magnetic plasma steering field.