Patent ID: 8290717

Claim:
A method to stabilize pressure in a plasma processing chamber, said method comprising: providing an upper electrode and a lower electrode for processing a substrate in said plasma processing chamber, said upper electrode and said lower electrode form a chamber gap; providing a first mechanism configured to mechanically couple to one of said upper electrode or said lower electrode; providing a set of confinement rings; providing a second mechanism configured to mechanically couple to said set of confinement rings; determining a plurality of conductance curves for different height values of said chamber gap; correlating confinement ring position (CRP) values of said set of confinement rings with said different height values of said chamber gap based on the plurality of conductance curves; specifying a first height value for said chamber gap; adjusting said chamber gap to said first height value by moving said first mechanism; determining a new CRP value from a current CRP value using said correlating; adjusting said set of confinement rings to said new CRP value in an open-loop manner by moving said second mechanism; and providing fine pressure adjustments in a closed-loop manner for said plasma processing chamber after adjusting said set of confinement rings.