Substrate cleaning chamber and cleaning and conditioning methods
A substrate cleaning chamber includes a contoured ceiling electrode having an arcuate surface that faces a substrate support and has a variable cross-sectional thickness to vary the gap size between the arcuate surface and the substrate support to provide a varying plasma density across the substrate support. A dielectric ring for the cleaning chamber comprises a base, a ridge, and a radially inward ledge that covers the peripheral lip of the substrate support. A base shield comprises a circular disc having at least one perimeter wall. Cleaning and conditioning processes for the cleaning chamber are also described.
1. A ceiling electrode for a cleaning chamber which comprises a substrate support having a substrate receiving surface and a support electrode, the ceiling electrode comprising:
a grounding ring; and
a contoured ceiling electrode consisting of metal, the contoured ceiling electrode comprising:
(a) an arcuate surface facing the substrate support, the arcuate surface having a diameter sized to extend across the substrate receiving surface of the substrate support and a cross-sectional thickness that changes across the substrate support to vary a dimension of a gap formed between the arcuate surface and the support electrode of the substrate support, thereby allowing a plasma density of a plasma formed between the arcuate surface and the substrate support to vary radially across the substrate support;
(b) an annular band extending downwardly from a periphery of the arcuate surface through the grounding ring to encircle the substrate support;
(c) a peripheral edge extending radially outwardly from the annular band, wherein said peripheral edge rests on the grounding ring; and wherein the annular band is spaced apart from a sidewall of the cleaning chamber by the grounding ring.
2. A ceiling electrode according to claim 1 wherein the arcuate surface extends across at least about 70% of the substrate receiving surface area of the substrate support.
3. A ceiling electrode according to claim 1 wherein the substrate support comprises central and peripheral regions, and wherein the arcuate surface comprises an arcuate profile that is shaped as a convex bulge to increase a plasma density at the peripheral region relative to the central region of the substrate support.
4. A ceiling electrode according to claim 1 wherein the arcuate surface is composed of an electrical conductor.
5. A cleaning chamber comprising the contoured ceiling electrode of claim 1 , and further comprising:
(1) the substrate support;
(2) an electrode power supply to supply a voltage bias across the support and contoured ceiling electrodes;
(3) a gas distributor for introducing a cleaning gas into the chamber; and
(4) a gas exhaust.
6. A cleaning chamber for etching a substrate in a plasma, the chamber comprising:
(a) a substrate support having a substrate receiving surface and comprising a support electrode;
(b) a contoured ceiling electrode having a metal arcuate surface that opposingly faces the substrate receiving surface of the substrate support, the metal arcuate surface having a diameter sized to extend across the substrate receiving surface area of the substrate support and a cross-sectional thickness that changes across the substrate support to vary a dimension of a gap formed between the metal arcuate surface and the support electrode of the substrate support, thereby providing a plasma density that varies radially across the substrate receiving surface;
(c) an electrode power supply to supply a voltage bias across the support and contoured ceiling electrode;
(d) a gas distributor for introducing a cleaning gas into the chamber;
(e) a gas exhaust;
(f) a grounding ring;
(g) a metal annular band that contacts the grounding ring, wherein the metal annular band extends downwardly from a periphery of the metal arcuate surface through the grounding ring to encircle the substrate receiving surface of the substrate support;
(h) a peripheral edge extending radially outwardly from the annular band, wherein said peripheral edge rests on the grounding ring; and wherein the annular band is spaced apart from a sidewall of the cleaning chamber by the grounding ring.
7. A chamber according to claim 6 wherein the metal arcuate surface of the contoured ceiling electrode comprises a convex bulge or concave depression.
8. A chamber according to claim 6 wherein the substrate receiving surface comprises central and peripheral regions, and wherein the metal arcuate surface comprises a convex bulge that is shaped to increase a plasma density at the peripheral region relative to the central region of the substrate support.
9. A chamber according to claim 6 wherein the metal arcuate surface and the metal annular band both consist of aluminum.
10. A chamber according to claim 9 comprising an electrical connector rod connected to the support electrode, and wherein the electrical connector rod comprises copper.
11. The cleaning chamber of claim 5 , wherein the gas distributor is positioned in a sidewall of the cleaning chamber.
12. The ceiling electrode of claim 1 , wherein the grounding ring is electrically interconnected with the contoured ceiling electrode and the contoured ceiling electrode and grounding ring can be maintained at a floating potential or grounded.
13. The cleaning chamber of claim 6 , wherein the gas distributor is positioned in a sidewall of the cleaning chamber.
14. The ceiling electrode of claim 6 , wherein the grounding ring is electrically interconnected with the contoured ceiling electrode and the contoured ceiling electrode and grounding ring can be maintained at a floating potential or grounded.