Patent ID: 7416677

Claim:
A method of etching a thin film on a substrate using a plasma processing system, comprising: disposing said substrate on a substrate holder in a plasma processing chamber; forming a processing plasma in a process space above and adjacent said substrate using a plasma generation system coupled to said plasma processing chamber; disposing an exhaust assembly within said plasma processing chamber such that said exhaust assembly substantially surrounds said substrate holder and separates said process space from a pumping space coupled to a vacuum pumping system; coupling electrical power to said exhaust assembly thereby forming a secondary plasma in order to alter said processing plasma; exposing said substrate to said altered processing plasma; the disposing of the exhaust assembly comprising: disposing a first exhaust plate around said substrate holder, said first exhaust plate having a plurality of openings to allow passage of process gas there-through; electrically insulating said first exhaust plate from said substrate holder and said plasma processing chamber; and disposing a second exhaust plate around said substrate holder, parallel with said first exhaust plate and below said first exhaust plate, said second exhaust plate having a plurality of openings to allow passage of process gas there-through; wherein said first exhaust plate is coupled to an electrical power source and said second exhaust plate is coupled to an electrical ground, and wherein said secondary plasma is formed between said first exhaust plate and said second exhaust plate during said coupling of electrical power.