Hybrid edge ring for plasma wafer processing
An edge ring assembly is disclosed for use in a plasma processing chamber, which includes an RF conductive ring positioned on an annular surface of a base plate and configured to surround an upper portion of the baseplate and extend underneath an outer edge of a wafer positioned on the upper surface of the baseplate, and a wafer edge protection ring positioned above an upper surface of the RF conductive ring and configured to extend over the outer edge of the wafer. The protection ring has an inner edge portion with a uniform thickness, which extends over the outer edge of the wafer, a conical upper surface extending outward from the inner edge portion to a horizontal upper surface, an inner annular recess which is positioned on the upper surface of the RF conductive and configured to extend over the outer edge of the wafer.
1. An edge ring assembly for use in a plasma processing chamber, comprising:
an RF conductive ring positioned on an annular surface of a base plate and configured to surround an upper portion of the base plate and extend underneath an outer edge of a wafer positioned on an upper surface of the base plate; and
a wafer edge protection ring positioned above an upper surface of the RF conductive ring and configured to extend over the outer edge of the wafer, the wafer edge protection ring having an inner annular edge portion with a uniform thickness, which is configured to extend over the outer edge of the wafer, a conical upper surface extending outward from the inner annular edge portion to a horizontal upper surface, and an inner annular recess which is positioned on the upper surface of the RF conductive ring and configured to extend over the outer edge of the wafer, the inner annular recess having a horizontal inner lower surface, which is positioned above the upper surface of the RF conductive ring, and wherein the horizontal inner lower surface extends outward from an inner vertical wall of the inner annular edge portion horizontally to an inner vertical wall of the inner annular recess, and the inner vertical wall of the inner annular recess being adjacent to an outer edge of the RF conductive ring, and wherein the horizontal inner lower surface of the wafer edge protection ring does not contact the RF conductive ring.
2. The assembly of claim 1 , comprising:
a bottom ring configured to be supported on the annular surface of the base plate and positioned between the RF conductive ring and the annular surface of the base plate.
3. The assembly of claim 2 , comprising:
a quartz ring surrounding an outer surface of the base plate and an outer edge of the bottom ring.
4. The assembly of claim 3 , comprising:
a centering ring surrounding an outer edge of the quartz ring and extending upward to a center annular recess within the wafer edge protection ring.
5. The assembly of claim 2 , wherein the bottom ring is an aluminum ring.
6. The assembly of claim 2 , wherein the bottom ring is an anodized aluminum ring.
7. The assembly of claim 1 , wherein the RF conductive ring has an annular recess on an inner portion of the RF conductive ring, and wherein the annular recess is configured to extend underneath the outer edge of the wafer.
8. The assembly of claim 1 , wherein the wafer edge protection ring has a center annular recess which is configured to receive a centering ring, and at least three recesses, each of the at least three recesses configured to receive a ceramic lift rod, which raises the wafer edge protection ring upward during wafer transfer.
9. The assembly of claim 1 , wherein the inner annular edge portion of the wafer edge protection ring has a thickness of about 0.030 inches to 0.060 inches.
10. The assembly of claim 1 , wherein the wafer edge protection ring is configured to extend about 0.5 mm to 3.0 mm over the outer edge of the wafer.
11. The assembly of claim 1 , wherein the wafer edge protection ring does not contact the wafer.
12. The assembly of claim 1 , wherein the RF conductive ring is made of silicon carbide (SiC) and has a resistivity of less than about 100 Ohm-cm.
13. The assembly of claim 1 , wherein the RF conductive ring is made of doped silicon (Si).
14. The assembly of claim 1 , wherein the wafer edge protection ring is made out of an RF conductive material.
15. A lower electrode assembly for use in a plasma processing chamber, comprising:
a base plate configured to receive a wafer on an upper surface of the base plate;
a bottom ring supported on an annular surface of the base plate and surrounding the base plate;
an RF conductive ring positioned on an upper surface of the bottom ring and surrounding an upper portion of the base plate and configured to extend underneath an outer edge of the wafer positioned on the upper surface of the base plate;
a wafer edge protection ring positioned above an upper surface of the RF conductive ring and configured to extend over the outer edge of the wafer, the wafer edge protection ring having an inner annular edge portion with a uniform thickness, which is configured to extend over the outer edge of the wafer, a conical upper surface extending outward from the inner annular edge portion to a horizontal upper surface, and an inner annular recess which is positioned on the upper surface of the RF conductive ring and configured to extend over the outer edge of the wafer, the inner annular recess having a horizontal inner lower surface, which is positioned above the upper surface of the RF conductive ring, and wherein the horizontal inner lower surface extends outward from an inner vertical wall of the inner annular edge portion horizontally to an inner vertical wall of the inner annular recess, the inner vertical wall of the inner annular recess being adjacent to an outer edge of the RF conductive ring, and
a quartz ring surrounding an outer surface of the base plate and an outer edge of the bottom ring; and
a centering ring surrounding an outer edge of the quartz ring and extending upward to a center annular recess within the wafer edge protection ring.
16. The lower electrode assembly of claim 15 , wherein the RF conductive ring has an annular recess on an inner portion of the RF conductive ring, and wherein the annular recess is configured to extend underneath the outer edge of the wafer.
17. The lower electrode assembly of claim 15 , wherein the wafer edge protection ring has at least three recesses, each of the at least three recesses configured to receive a ceramic lift rod, which raises the wafer edge protection ring upward during wafer transfer.
18. The lower electrode assembly of claim 15 , wherein the inner annular edge portion of the wafer edge protection ring has a thickness of about 0.030 inches to 0.060 inches.
19. The lower electrode assembly of claim 15 , wherein the wafer edge protection ring is configured to extend about 0.5 mm to 3.0 mm over the outer edge of the wafer.
20. The lower electrode assembly of claim 15 , wherein the wafer edge protection ring does not contact the wafer.
21. The lower electrode assembly of claim 15 , wherein the RF conductive ring is made of silicon carbide (SiC) and has a resistivity of less than about 100 Ohm-cm.
22. The lower electrode assembly of claim 15 , wherein the RF conductive ring is made of doped silicon (Si).
23. The lower electrode assembly of claim 15 , wherein the wafer edge protection ring is made out of an RF conductive material.
24. The lower electrode assembly of claim 15 , wherein the bottom ring is an aluminum ring.
25. The lower electrode assembly of claim 15 , wherein the bottom ring is an anodized aluminum ring.
26. The lower electrode assembly of claim 15 , wherein the base plate is an electrostatic chuck assembly (ESC).