RF multi-feed structure to improve plasma uniformity

1. A plasma source assembly comprising:

a pie-shaped housing having an inner peripheral edge, an outer peripheral edge and side walls, the housing including an electrically grounded front face, the inner peripheral edge and outer peripheral edge defining a length and the side walls defining a width, the width increasing along the length from the inner peripheral edge to the outer peripheral edge;

a pie-shaped RF hot electrode within the housing spaced from the electrically grounded front face and defining a gap;

an end dielectric bounding the pie-shaped RF hot electrode at the inner peripheral edge, the outer peripheral edge and the side walls positioned between the RF hot electrode and the housing;

a first coaxial RF feed line including an outer conductor and an inner conductor separated by an insulator, the outer conductor in electrical communication with electrical ground and the inner conductor in electrical communication with the RF hot electrode, the first coaxial RF feed line connecting to the RF hot electrode at a first distance from the inner peripheral edge of the housing; and

a second coaxial RF feed line including an outer conductor and an inner conductor separated by an insulator, the outer conductor in electrical communication with electrical ground and the inner conductor in electrical communication with the RF hot electrode, the second coaxial RF feed line connecting to the RF hot electrode at a second distance from the inner peripheral edge of the housing, the second distance being greater than the first distance.

2. The plasma source assembly of claim 1 , wherein an RF feed line connected to a power source, the RF feed line splitting into the first coaxial RF feed line and the second coaxial RF feed line at a junction.

3. The plasma source assembly of claim 2 , wherein the junction is closer to one of the first coaxial RF feed line and the second coaxial RF feed line than the other of the first coaxial RF feed line and the second coaxial RF feed line.

4. The plasma source assembly of claim 2 , wherein the junction comprises a controller.

5. The plasma source assembly of claim 4 , wherein the controller modifies RF power from the RF feed line to generate a first RF power in the first coaxial RF feed line and a second RF power different from the first RF power in the second coaxial RF feed line.

6. The plasma source assembly of claim 4 , wherein the controller modifies RF phase to generate a first phase in the first coaxial RF feed line and a second phase different from the first phase in the second coaxial RF feed line.

7. The plasma source assembly of claim 1 , further comprising a first power source connected to the first coaxial RF feed line and a second power source connected to the second coaxial RF feed line.

8. The plasma source assembly of claim 1 , wherein the RF hot electrode is separated into an inner peripheral region and an outer peripheral region, the inner peripheral region electrically isolated from the outer peripheral region.

9. The plasma source assembly of claim 8 , further comprising a dielectric between the inner peripheral region and the outer peripheral region of the RF hot electrode.

10. The plasma source assembly of claim 1 , wherein the RF hot electrode comprises a plurality of holes therethrough that permit a gas to pass through into the gap.

11. The plasma source assembly of claim 1 , wherein the grounded front face of the housing comprises a plurality of apertures that allow a gas to pass from the gap to a processing region on an opposite side of the grounded front face.

12. A plasma source assembly comprising:

a housing including an inner peripheral edge, an outer peripheral edge, two side walls connecting the inner peripheral edge and the outer peripheral edge, an electrically grounded front face comprising a plurality of openings therethrough;

an RF hot electrode within the housing having a body with a front surface, a back surface, sides, a first end adjacent the inner peripheral edge and a second end adjacent the outer peripheral edge, the front surface of the RF hot electrode spaced from the grounded front face of the housing to form a gap;

an end dielectric in contact with each of the first end, the second end and the sides of the RF hot electrode positioned between the RF hot electrode and the housing; and

an RF feed line including an outer conductor and an inner conductor separated by an insulator, the RF feed line splitting at a junction into a first RF feed line and a second RF feed line, the first RF feed line in electrical communication with the RF hot electrode a first distance from the inner peripheral edge of the housing and the second RF feed line in electrical communication with the RF hot electrode a second distance from the inner peripheral edge of the housing, the second distance greater than the first distance.

13. The plasma source assembly of claim 12 , wherein the junction comprises a controller.

14. The plasma source assembly of claim 13 , wherein the controller modifies RF power from the RF feed line to generate a first RF power in the first coaxial RF feed line and a second RF power different from the first RF power in the second coaxial RF feed line.

15. The plasma source assembly of claim 13 , wherein the controller modifies RF phase to generate a first phase in the first coaxial RF feed line and a second phase different from the first phase in the second coaxial RF feed line.

16. The plasma source assembly of claim 12 , wherein the RF hot electrode is separated into an inner peripheral region and an outer peripheral region, the inner peripheral region electrically isolated from the outer peripheral region.

17. The plasma source assembly of claim 16 , further comprising a dielectric between the inner peripheral region and the outer peripheral region of the RF hot electrode.

18. A modular plasma source assembly comprising:

a wedge-shaped elongate housing having an inner peripheral edge, an outer peripheral edge, two side walls connecting the inner peripheral edge and the outer peripheral edge, an electrically grounded front face comprising a plurality of openings therethrough, a length defined by the inner peripheral edge and outer peripheral edge and a width defined by the two side walls, the width increasing from the inner peripheral edge to the outer peripheral edge;

an RF hot electrode within the housing having a body with a front surface, a back surface, elongate sides, a first end adjacent the inner peripheral edge and a second end adjacent the outer peripheral edge of the housing, the front surface of the RF hot electrode spaced from the front face of the housing to form a gap;

an end dielectric in contact with each of the first end, the second end and the sides of the RF hot electrode positioned between the RF hot electrode and the housing;

an RF feed line having an outer conductor and an inner conductor separated by an insulator, the RF feed line in communication with a power source and a junction;

a first RF feed line extending a first length from the junction to the RF hot electrode, the first RF feed line having an outer conductor and an inner conductor separated by an insulator, the outer conductor in electrical communication with ground and the inner conductor in electrical communication with the RF hot electrode and spaced a first distance from the inner peripheral edge of the housing; and

a second RF feed line extending a second length from the junction to the RF hot electrode, the second RF feed line having an outer conductor and an inner conductor separated by an insulator, the outer conductor in electrical communication with ground and the inner conductor in electrical communication with the RF hot electrode and spaced a second distance from the inner peripheral edge of the housing, the second distance being greater than the first distance.

19. The plasma source assembly of claim 18 , wherein the first length and second length are different.

20. The plasma source assembly of claim 19 , wherein the junction comprises a controller to modulate one or more of power and phase.