Patent ID: 8460567

Claim:
A method of etching a substrate, comprising: disposing a substrate in a processing system, said processing system comprising a first chamber region, a second chamber region, and a substrate treatment region, wherein a separation member is disposed between said first chamber region and said second chamber region, said first chamber region having a first pressure, said second chamber region having a second pressure, said substrate treatment region having a third pressure; forming plasma in said first chamber region; extracting electrons from said plasma; collision-quenching said electrons in order to form less energetic electrons; forming a quiescent plasma with a population of negatively-charged ions using said less energetic electrons in said second chamber region; and etching one or more features in said substrate by exposing said substrate to said population of negatively-charged ions in said quiescent plasma; wherein said forming plasma further comprises: providing a first process gas for said forming said plasma, wherein said first process gas comprises as an incipient constituent a noble gas; and disposing a pressure barrier between said second chamber region and said substrate treatment region; wherein said pressure barrier is configured to produce a controlled pressure differential between said second chamber region and said substrate treatment region, said pressure barrier comprising one or more openings therethrough to permit adjusting said second pressure for efficient collision quenching in said second chamber region, wherein controlling the pressure differential to achieve efficient said collision-quenching of said electrons is performed using a pressure control system; wherein said separation member comprise openings sufficiently large to permit electron extraction and sufficiently small to prevent electron heating across said separation member; and wherein said first chamber region having a first power source, said first power source being a direct current (DC) negative voltage in order to reduce a plasma potential of said plasma or to reduce electron temperature of said plasma or both.