Patent Number: 
Section: claims

1. A method of processing a workpiece, the method comprising:providing the workpiece in a chamber;providing a plurality of electrodes between a top of the chamber and the workpiece;generating a plasma containing ions between the plurality of electrodes and the workpiece, an ion density in an inner portion of the plasma being greater than the ion density in an outer portion of the plasma portion, the outer portion being between the inner portion and a wall of the chamber; andproviding a bias voltage to the plurality of electrodes and dispersing at least a portion of the ions in the inner portion so that the ion density in the inner portion is substantially equal to the ion density in the outer portion. 2. The method according to claim 1, the method further comprising:attracting ions to the workpiece from the inner and outer portions of the plasma. 3. The method according to claim 1, wherein the providing the bias voltage to the plurality of electrodes comprises independently biasing the plurality of electrodes. 4. The method according to claim 1, wherein the providing the bias voltage to the plurality of electrodes comprises positively biasing the plurality of electrodes. 5. The method according to claim 1, wherein the providing the bias voltage to the plurality of electrodes comprises negatively biasing the plurality of electrodes. 6. The method according to claim 1, the method further comprising:coupling the plurality of electrodes to one or more power supplies, wherein the one or more power supplies provide a pulsed bias voltage having a duty cycle. 7. The method according to claim 6, the method further comprising:adjusting the duty cycle of the pulsed bias voltage provided to the plurality of electrodes. 8. The method according to claim 1, the method further comprising:providing a magnetic field in same direction as an electric field created by the biasing the plurality of electrodes. 9. The method according to claim 1, wherein the plurality of electrodes comprises a first electrode disposed above the inner portion of the plasma and a second electrode disposed above the outer portion of the plasma, and wherein the first electrode is applied with a first bias voltage and the second electrode is applied with a second bias voltage. 10. The method according to claim 9, wherein the first bias voltage is more positive than the second bias voltage. 11. The method according to claim 9, wherein the first bias voltage is less positive than the second bias voltage. 12. The method according to claim 11, wherein the providing the bias voltage to the first and second electrodes comprises biasing the first electrodes with a first bias voltage and the second electrodes with a second bias voltage. 13. The method according to claim 12, wherein the first bias voltage is more positive than the second bias voltage. 14. The method according to claim 12, wherein the first bias voltage is less positive than the second bias voltage. 15. A method of processing a workpiece, the method comprising:providing the workpiece in a plasma chamber;providing first and second electrodes between a top of the plasma chamber and the workpiece;generating a plasma containing ions between the first and second electrodes and the workpiece, the plasma comprising a first plasma portion disposed beneath the first electrodes and a second plasma portion disposed beneath the second electrode, wherein the first plasma portion has greater ion density than the second plasma portion;providing a bias voltage to the first and second electrodes and dispersing at least a portion of the ions in the first plasma portion so that the ion density in the first plasma portion is substantially equal to the ion density in the second plasma portion; andbiasing the workpiece and attracting ions to the workpiece from the first and second portions of the plasma having substantially equal ion density. 16. The method according to claim 15, wherein the first plasma portion is disposed closer to a middle of the plasma than the second plasma portion and wherein the second plasma portion is disposed closer to a periphery of the plasma than the first plasma portion. 17. The method according to claim 15, wherein the second plasma portion is disposed closer to a middle of the plasma than the first plasma portion and wherein the first plasma portion is disposed closer to a periphery of the plasma than the second plasma portion. 18. The method according to claim 15, wherein the providing the bias voltage to the first and second electrodes comprises independently biasing at least one of the plurality of electrodes. 19. The method according to claim 15, wherein the providing the bias voltage to the first and second electrodes comprises positively biasing at least one of the plurality of electrodes. 20. The method according to claim 15, wherein the providing the bias voltage to the first and second electrodes comprises negatively biasing at least one of the plurality of electrodes.