Patent ID: 9431218
Filing Date: 2016-08-30
CPC Classification: H01J

Claim Text:
1. A method of treating a substrate with plasma, comprising: disposing a substrate in a plasma processing system having a power source having a positive terminal and a negative terminal, the positive terminal coupled to ground; disposing a hollow cathode plasma source including a plurality of independently controlled hollow cathodes within said plasma processing system, wherein each hollow cathode is coupled to the negative terminal of the power source through a respective adjustable conductive element, wherein each hollow cathode is independently controlled via the respective adjustable conductive element, wherein each hollow cathode defines a plasma discharge space bounded by cathode walls opposing one another about a central axis that intersects a cathode outlet at one end of said hollow cathode allowing fluid communication with an interior space of said plasma processing system; disposing a grid between said cathode outlet of said plurality of hollow cathodes and said substrate; electrically coupling said grid to electrical ground; generating plasma in said plasma discharge space by ion-induced secondary electron emission of energetic electrons that move along a trajectory substantially normal to said central axis; and diffusing lower energy electrons along a trajectory substantially parallel to said central axis across a first region of said interior space between said cathode outlet and said grid, through said grid, and into a second region of said interior space in fluid contact with said substrate.