Inductively coupled plasma source with symmetrical rf feed and reactance elements

Abstract

A plasma reactor includes a window assembly, inner, middle and outer coil antennas adjacent the window assembly, inner, middle and outer current distributors respectively coupled to the inner, middle and outer coil antennas, a ceiling plate overlying the window assembly, first, second and third RF power terminals, and first, second and third axial RF power feeds connected between respective ones of the first, second and third RF power terminals and respective ones of the inner, middle and outer current distributors. The third axial RF power feed includes an outer RF power distribution cylinder surrounding the first and second RF axial power feeds. Plural spaced-apart reactance elements are electrically connected to the outer RF power distribution cylinder.

1 . A plasma reactor comprising:
 a window assembly;   inner, middle and outer coil antennas adjacent said window assembly;   inner, middle and outer current distributors coupled to said inner, middle and outer coil antennas, respectively;   a ceiling plate overlying said window assembly and first, second and third RF power terminals at said ceiling plate;   first, second and third axial RF power feeds connected between respective ones of said first, second and third RF power terminals and respective ones of said inner, middle and outer current distributors, wherein said third axial RF power feed comprises an outer RF power distribution cylinder surrounding said first and second RF axial power feeds; and   plural spaced-apart reactance elements electrically connected to said outer RF power distribution cylinder.   
     
     
         2 . The plasma reactor of  claim 1  further comprising a middle RF distribution ring below said outer RF distribution cylinder and coupled to said second RF axial power feed. 
     
     
         3 . The plasma reactor of  claim 2  further comprising:
 plural radial middle arms extending outwardly from said middle RF distribution ring, and plural axial middle legs extending from said plural radial middle arms to spaced apart locations on said middle current distributor. 
 
     
     
         4 . The plasma reactor of  claim 3  further comprising:
 plural radial outer arms extending outwardly from said outer RF distribution cylinder and plural axial outer legs extending from said plural radial arms to spaced apart locations on said outer current distributor. 
 
     
     
         5 . The plasma reactor of  claim 4  further comprising a ground plate below said ceiling plate and above said middle current distributor, said plural axial middle legs extending through said ground plate. 
     
     
         6 . The plasma reactor of  claim 5  wherein said plural axial outer legs extend through said ground plate. 
     
     
         7 . The plasma reactor of  claim 6  wherein:
 each one of said inner, middle and outer coil antennas comprises plural conductors having RF supply ends; 
 each one of said inner, middle and outer current distributors comprises an axially symmetric hollow body comprising a bottom facing the supply ends of the plural conductors of the corresponding one of said inner, middle and outer coil antennas. 
 
     
     
         8 . (canceled) 
     
     
         9 . The plasma reactor of  claim 1  wherein said reactance elements are coupled in parallel between said outer RF power distribution cylinder and said ceiling plate. 
     
     
         10 . The plasma reactor of  claim 9  wherein said reactance elements comprise discrete capacitors. 
     
     
         11 . The plasma reactor of  claim 1  wherein said reactance elements are uniformly spaced about a periphery of said outer RF power distribution cylinder. 
     
     
         12 . The plasma reactor of  claim 1  wherein said third axial RF power feed further comprises a top conductor coupled to said outer RF power distribution cylinder. 
     
     
         13 . The plasma reactor of  claim 12  wherein:
 said top conductor comprises an upper axial section aligned with said third RF power terminal, a lower axial section coupled to said outer RF power distribution cylinder, and a radial section connected between said upper and lower axial sections. 
 
     
     
         14 - 18 . (canceled) 
     
     
         19 . The plasma reactor of  claim 1  further comprising:
 a plenum plate spaced from and below said ceiling plate and comprising a central opening. 
 
     
     
         20 . The plasma reactor of  claim 19  wherein said outer RF distribution cylinder extends through said central opening. 
     
     
         21 . The plasma reactor of  claim 1  wherein said first and second axial RF power feeds comprise first and second RF connection rods respectively. 
     
     
         22 . The plasma reactor of  claim 1  wherein said first axial RF power feed comprises an RF connection rod and said second axial RF power feeds comprises an inner RF power distribution cylinder surrounding said RF connection rod. 
     
     
         23 . The plasma reactor of  claim 1  wherein said third axial RF power feed further comprises a flange extending radially outwardly from a top of said outer RF power distribution cylinder. 
     
     
         24 . The plasma reactor of  claim 22  wherein said third axial RF power feed further comprises an axial lip extending upwardly from an outer edge of the flange. 
     
     
         25 . The plasma reactor of  claim 23 , wherein said plural spaced-apart reactance elements are physically connected to said axial lip. 
     
     
         26 . The plasma reactor of  claim 1 , wherein said plural spaced-apart plural spaced-apart reactance elements are physically connected to said outer RF power distribution cylinder.