Plasma source with floating electrodes
A plasma source assembly for use with a substrate processing chamber is described. The assembly includes a spring which is disposed between electrodes and a dielectric ring.
1. A plasma source assembly comprising:
a first electrode comprising a conductive plate having a top surface, a bottom surface, and an outer peripheral edge;
a second electrode comprising a conductive plate having a top surface, a bottom surface, and an outer peripheral edge;
a dielectric spacer separating the first electrode and the second electrode and disposed at the outer peripheral edge of the first electrode and the outer peripheral edge of the second electrode;
a power feed electrically connected to the first electrode and the second electrode; and
a first helical spring having a shape of a ring disposed between the bottom surface of the first electrode and the dielectric spacer and adjacent to the outer peripheral edge of the first electrode; and
a second helical spring in the shape of a ring disposed between the top surface of the second electrode and the dielectric spacer and adjacent to the outer peripheral edge of the second electrode, wherein each of the first helical spring and the second helical spring comprises a conductive material.
2. The plasma source assembly of claim 1 , wherein each of the first helical spring and the second helical spring comprises a metal.
3. The plasma source assembly of claim 2 , wherein the metal is an alloy.
4. The plasma source assembly of claim 3 , wherein the alloy comprises cobalt, chromium, nickel and molybdenum.
5. The plasma source assembly of claim 1 , further comprising a purge ring surrounding and in contact with the dielectric spacer and a power feed in electrical communication with the purge ring, and wherein the conductive material has an electrical resistivity that permits electrical communication between purge ring, the first electrode and the purge ring and the second electrode.
6. The plasma source assembly of claim 5 , wherein the purge ring comprises a metal and the dielectric spacer comprises a ceramic.
7. The plasma source assembly of claim 6 , wherein the ceramic comprises aluminum oxide.
8. The plasma source assembly of claim 1 , wherein the first electrode and the second electrode are spaced apart to provide a gap between the first electrode and the second electrode, and the first electrode and the second electrode comprise a material that allows a plasma to be formed between the first electrode and the second electrode.
9. The plasma source assembly of claim 8 , wherein the first electrode comprises a plurality of apertures that allow a gas to pass through the first electrode and into the gap.
10. The plasma source assembly of claim 1 , wherein the first helical spring is in contact with the bottom surface of the first electrode adjacent to the outer peripheral edge of the first electrode, and the second helical spring is in contact with the top surface of the second electrode adjacent to the outer peripheral edge of the second electrode.
11. The plasma source assembly of claim 9 , wherein the first electrode and the second electrode comprise silicon and the second electrode includes a silicon carbide cladding.
12. The plasma source assembly of claim 1 , wherein
the first electrode includes a plurality of apertures allowing a gas to flow therethrough; and
the second electrode include a plurality of apertures allowing a gas to flow therethrough,
the first helical spring comprising a metal alloy and coaxial with the outer peripheral edge of the first electrode, and
the second helical spring comprising a metal alloy and coaxial with the outer peripheral edge of the second electrode.
13. A method of processing a substrate in a substrate processing chamber including the plasma source of claim 12 , the method comprising:
placing a substrate in the substrate processing
and
striking a plasma between the first electrode and the second electrode.
14. The method of claim 13 , wherein the the first helical spring and the second helical spring each comprises an alloy comprising cobalt, chromium, nickel and molybdenum.
15. The method of claim 14 , wherein the first electrode and the second electrode comprise silicon and the second electrode includes a silicon carbide cladding.
16. The method of claim 15 , wherein the dielectric spacer comprises a ceramic.
17. The method of claim 16 , wherein the ceramic is aluminum oxide.
18. The method of claim 13 , further comprising forming a film on the substrate.