Patent ID: 8342122

Claim:
A plasma processing system having a plasma processing chamber for processing a substrate, said plasma processing chamber comprising: an upper electrode, said upper electrode having a first upper electrode portion and a second upper electrode portion, said first upper electrode portion annularly surrounds said second upper electrode portion; a lower electrode, said lower electrode having a first lower electrode portion and a second lower electrode portion, said first lower electrode portion annularly surrounds said second lower electrode portion, said second lower electrode portion having a substrate bearing surface configured to support said substrate during said processing, wherein at least one of said upper electrode and said lower electrode is movable in a direction that is perpendicular to said substrate bearing surface, wherein an upper surface of said first lower electrode portion is non-planar with respect to said substrate-bearing surface such that a first gap between said upper surface of said first lower electrode portion and a lower surface of said first upper electrode portion is smaller than a second gap between said substrate bearing surface and a substrate-facing surface of said second upper electrode portion, wherein said second lower electrode portion is powered by a radio frequency (RF) power source during said processing, wherein said plasma processing chamber is configured to be operable during at least two regimes, a first regime of said two regimes involving disposing said upper electrode and said lower electrode such that plasma is sustained between said substrate bearing surface of said second lower electrode portion and said substrate-facing surface of said second upper electrode portion, said plasma is also sustained in said first regime between said upper surface of said first lower electrode portion and said lower surface of said first upper electrode portion, a second regime of said two regimes involving disposing said upper electrode and said lower electrode such that said plasma is sustained between said substrate bearing surface of said second lower electrode portion and a substrate-facing surface of said second upper electrode portion, said plasma is however not sustained in said second regime between said upper surface of said first lower electrode portion and said lower surface of said first upper electrode portion, an area ratio of RF coupling between said upper electrode and said lower electrode is about 1:1 in said second regime.