METHODS AND APPARATUS FOR WAFER AREA PRESSURE CONTROL IN AN ADJUSTABLE GAP PLASMA CHAMBER

摘要

In a plasma processing chamber, a method and an arrangement to stabilize pressure are provided. The method includes providing coarse pressure adjustments in an open-loop manner and thereafter providing fine pressure adjustments in a closed-loop manner. The coarse pressure adjustments are performed by rapidly re-position confinement rings employing an assumed linear relationship between the conductance and the confinement rings position to bring the pressure in the plasma generating region quickly to roughly a desired set point. The fine pressure adjustments are performed by at least employing mechanical vacuum pump(s), turbo pump(s), confinement ring positioning and/or combinations thereof to achieve a derive pressure set point.