Apparatus and method for providing a uniform flow of gas
Outer distribution rings and gas distribution apparatus with outer distribution rings to deliver a gas flow to a process region of a process chamber are described. The outer distribution rings include at least one plenum in fluid communication with a plurality of openings forming a plurality of trenches to allow gas to flow from the plenum through the openings and down an inner peripheral face of the outer distribution ring.
1. An outer distribution ring comprising
a round body having a top, bottom, inner diameter with an inner diameter face and an outer diameter with an outer diameter face;
a plenum formed in the top of the round body, the plenum having an outer peripheral face and an inner peripheral face defining a width and having a volume in a range of about 100 mL to about 900 mL; and
a plurality of openings in the inner peripheral face of the plenum forming a plurality of trenches connecting the plenum with the inner diameter face, the plurality of trenches substantially equally spaced about the inner peripheral face, the plurality of trenches extending from a top of the inner diameter face to a bottom of the inner diameter face, and the trenches having a combined volume in a range of about 20 mL to about 240 mL,
wherein a ratio of the combined volume of the trenches to the volume of the plenum is in the range of about 10% to about 30%.
2. The outer distribution ring of claim 1 , wherein the plenum has a volume in the range of about 400 mL to about 600 mL.
3. The outer distribution ring of claim 2 , wherein the trenches have a combined volume in the range of about 40 mL to about 180 mL.
4. The outer distribution ring of claim 1 , further comprising a second plenum in fluid communication with the plenum through a plurality of apertures.
5. The outer distribution ring of claim 1 , wherein the inner diameter face is shaped so that a gas flowing down the inner diameter face from the plurality of trenches flows substantially concentric with an axis of the body.
6. The outer distribution ring of claim 1 , further comprising a gas inlet in fluid communication with the plenum.
7. The outer distribution ring of claim 6 , wherein the gas inlet connects to the plenum through the top of the body.
8. The outer distribution ring of claim 6 , wherein the gas inlet connects to the plenum through the outer diameter face of the body.