Plasma reactor apparatus with an inductive plasma source and a VHF capacitively coupled plasma source with variable frequency

Abstract

A plasma reactor for processing a workpiece includes a reactor chamber and a workpiece support within the chamber, the chamber having a ceiling facing the workpiece support, an inductively coupled plasma source power applicator overlying the ceiling, and an RF power generator coupled to the inductively coupled source power applicator, a capacitively coupled plasma source power applicator comprising a source power electrode at one of: (a) the ceiling (b) the workpiece support, and plural VHF power generators of different fixed frequencies coupled to the capacitively coupled source power applicator, and a controller for independently controlling the power output levels of the plural VHF generators so as to control an effective VHF frequency applied to the source power electrode. In a preferred embodiment, the reactor further includes a plasma bias power applicator including a bias power electrode in the workpiece support and one or more RF bias power generators of different frequencies coupled to the plasma bias power applicator.

1 . A plasma reactor for processing a workpiece, comprising: 
 a reactor chamber and a workpiece support within said chamber, said chamber having a ceiling facing said workpiece support;    an inductively coupled plasma source power applicator overlying said ceiling, and an RF power generator coupled to said inductively coupled source power applicator;    a capacitively coupled plasma source power applicator comprising a source power electrode at one of: (a) said ceiling (b) said workpiece support, and plural VHF power generators of different fixed frequencies coupled to said capacitively coupled source power applicator; and    a controller for independently controlling the power output levels of said plural VHF generators so as to control an effective VHF frequency applied to said source power electrode.    
   
   
       2 . The reactor of  claim 1  further comprising: 
 a plasma bias power applicator comprising a bias power electrode in said workpiece support and at least a first RF bias power generator coupled to said plasma bias power applicator.    
   
   
       3 . The reactor of  claim 2  wherein said source power electrode is at said ceiling and comprises: 
 process gas distribution apparatus comprising a gas distribution showerhead in said ceiling.    
   
   
       4 . The reactor of  claim 1  wherein said controller is capable of adjusting the relative amounts of power simultaneously coupled to plasma in said chamber by said inductively coupled plasma source power applicator and said capacitively coupled plasma source power applicator.  
   
   
       5 . The reactor of  claim 2  further comprising: 
 a second RF bias power generator coupled to said bias power electrode, said first and second RF bias power generators providing RF power at a low frequency and at a high frequency, respectively;    a second controller capable of adjusting the relative amounts of power simultaneously coupled to said bias power electrode by said first and second RF bias power generators.    
   
   
       6 . The reactor of  claim 5  wherein said source power electrode is at said workpiece support and wherein said source power electrode and said bias power electrode are the same electrode.  
   
   
       7 . The reactor of  claim 3  wherein said VHF source power generator is coupled to said electrode at said ceiling, said reactor further comprising a VHF bandpass filter connected between said bias power electrode and ground whereby said bias power electrode is a counterelectrode for said electrode at said ceiling.  
   
   
       8 . The reactor of  claim 7  further comprising an LF/HF bandpass filter connected between said ceiling electrode and ground, whereby said ceiling electrode is a counterelectrode for bias power applied to said bias power electrode.  
   
   
       9 . The reactor of  claim 4  wherein said VHF source power generator is coupled to said bias power electrode at said workpiece support, said electrode at said ceiling being connected to ground whereby said electrode at said ceiling is a counterelectrode for VHF power applied to said bias power electrode and for HF or LF bias power applied to said bias power electrode.  
   
   
       10 . The reactor of  claim 1  wherein said controller is capable of controlling the evacuation rate of said chamber.  
   
   
       11 . The reactor of  claim 1  wherein said source power electrode is at said ceiling and is slotted to permit inductive coupling of RF power therethrough.  
   
   
       12 . The reactor of  claim 1  wherein said source power electrode is at said ceiling and is formed of a semiconductor material capable of functioning as an electrode while permitting inductive coupling of RF power therethrough.  
   
   
       13 . The reactor of  claim 3  wherein said gas distribution showerhead is formed of a non-conductive material.  
   
   
       14 . The reactor of  claim 5  wherein said low frequency and said high frequency are greater and less than, respectively, a sheath ion transit frequency of plasma in said chamber.  
   
   
       15 . The reactor of  claim 1  wherein said inductively coupled plasma source power applicator comprises a coil antenna.  
   
   
       16 . The reactor of  claim 15  wherein said coil antenna comprises a helically wound conductor.  
   
   
       17 . The reactor of  claim 15  wherein said coil antenna comprises plural parallel helically wound conductors.  
   
   
       18 . The reactor of  claim 15  wherein said coil antenna is planar.  
   
   
       19 . The reactor of  claim 15  wherein said coil antenna is dome-shaped.  
   
   
       20 . The reactor of  claim 15  wherein said coil antenna is solenoidal.  
   
   
       21 . The reactor of  claim 3  wherein said ceiling and said gas distribution showerhead have a dome shape.  
   
   
       22 . The reactor of  claim 21  wherein said dome shape 
 is one of: (a) smooth, (b) stepped.    
   
   
       23 . The reactor of  claim 21  wherein said dome shaped is center high relative a ceiling-to-workpiece distance.