Methods and apparatus for igniting a low pressure plasma

Abstract

A plasma ignition apparatus configured to strike a plasma in a plasma processing chamber is provided. The apparatus includes an ignition electrode configured to strike a plasma from a gas mixture at a strike frequency. The apparatus also includes at least one powered electrode configured to sustain the plasma at a target frequency, wherein the strike frequency is greater than the target frequency. A first surface area of the ignition electrode is substantially less than a second surface area of the at least one powered electrode, and the ignition electrode is de-energized while processing a substrate in the plasma processing chamber.

1 - 10 . (canceled) 
   
   
       11 . A plasma ignition apparatus configured to strike a plasma in a plasma processing chamber, comprising:
 an ignition electrode configured to strike a plasma from a gas mixture at a strike frequency;   at least one powered electrode configured to sustain said plasma at a target frequency, wherein said strike frequency is greater than said target frequency, a first surface area of said ignition electrode is substantially less than a second surface area of said at least one powered electrode, and said ignition electrode is de-energized while processing a substrate in said plasma processing chamber.   
   
   
       12 . The apparatus of  claim 11  wherein said strike frequency is employed only long enough to form said plasma. 
   
   
       13 . The apparatus of  claim 11  wherein said plasma processing system represents one of an inductively-coupled plasma processing system and a capacitively-coupled plasma processing system. 
   
   
       14 . The apparatus of  claim 11  wherein said substrate represents one of a semiconductor wafer for producing integrated circuit and a flat panel substrate. 
   
   
       15 . The apparatus of  claim 11  wherein said ignition electrode is powered by a strike radio frequency (RF) generator. 
   
   
       16 . In a plasma processing system having a plasma processing chamber, at least one powered electrode and an ignition electrode, an apparatus for igniting a plasma, comprising:
 means for introducing a substrate into said plasma processing chamber;   means for flowing a gas mixture into said plasma processing chamber at a pressure;   means for energizing said ignition electrode at a strike frequency;   means for striking a plasma from said gas mixture with said ignition electrode;   means for energizing said at least one powered electrode with a target frequency, wherein said strike frequency is greater than said target frequency;   means for de-energizing said ignition electrode while processing said substrate in said plasma processing chamber.   
   
   
       17 . The apparatus of  claim 16 , wherein a first surface area of said ignition electrode is substantially less than a second surface area of said at least one powered electrode. 
   
   
       18 . The apparatus of  claim 16  wherein said strike frequency is employed only long enough to form said plasma. 
   
   
       19 . The apparatus of  claim 16  wherein said plasma processing system is one of an inductively-coupled plasma processing system and a capacitively-coupled plasma processing system. 
   
   
       20 . The apparatus of  claim 16  wherein said substrate represents one of a semiconductor wafer for producing integrated circuit and a flat panel substrate. 
   
   
       21 . The apparatus of  claim 16  wherein said ignition electrode is powered by a strike radio frequency (RF) generator. 
   
   
       22 . The apparatus of  claim 16  wherein said plasma is sustained at a pressure of less than 100 mT. 
   
   
       23 . The apparatus of  claim 16  wherein said pressure is a target pressure. 
   
   
       24 . The apparatus of  claim 16  wherein a power of said at least one powered electrode is a target power. 
   
   
       25 . The apparatus of  claim 16  wherein said gas mixture is a target gas mixture. 
   
   
       26 . The apparatus of  claim 11  wherein said ignition electrode is coupled to a plasma electrical probe. 
   
   
       27 . The apparatus of  claim 26  wherein said plasma electrical probe is a voltage/current probe, said voltage/current probe being configured to measure processing conditions in said plasma processing chamber. 
   
   
       28 . The apparatus of  claim 11  wherein said at least one powered electrode includes a top electrode and a bottom electrode, said top electrode being grounded and said bottom electrode being powered by a low frequency RF generator, said low frequency RF generator being different from said strike RF generator. 
   
   
       29 . The apparatus of  claim 16  wherein said ignition electrode is coupled to a plasma electrical probe. 
   
   
       30 . The apparatus of  claim 30  wherein said plasma electrical probe is a voltage/current probe, said voltage/current probe being configured to measure processing conditions in said plasma processing chamber.