Patent ID: 7645357

Claim:
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; 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; 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; 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; wherein said plural VHF generators comprise a first VHF generator of fixed VHF frequency f 1 with output power level a 1 and a second VHF generator of fixed VHF frequency f 2 with output power level a 2 and wherein said controller governs said output power levels to control an effective VHF frequency f eff within a range from f 1 to f 2 in accordance with f eff =[a 1 f 1 +a 2 f 2 ]/(a 1 +a 2 ).