Patent ID: 7722737

Claim:
A gas distribution system for providing a gas flow to a process chamber comprising: a gas ring including an outer surface and an inner surface; a gas inlet disposed at the outer surface of the gas ring, the gas inlet being fluidicly coupled with a first arcuate channel which is disposed between the outer surface and the inner surface of the gas ring; a plurality of gas outlets distributed over the inner surface of the gas ring, the plurality of gas outlets being fluidicly coupled with a second arcuate channel which is disposed between the outer surface and the inner surface of the gas ring; and a plurality of holes extending from the first arcuate channel to the second arcuate channel to fluidicly couple the first arcuate channel to the second arcuate channel within the gas ring, the first arcuate channel being fluidicly coupled to the process chamber only through the second arcuate channel, the plurality of holes comprising a first hole and a second hole, the first hole having a first angle from the inlet and a first diameter, the second hole having a second angle from the inlet and a second diameter, the first hole extending from the first arcuate channel to the second arcuate channel with the first angle and the first diameter, the second hole extending from the first arcuate channel to the second arcuate channel with the second angle and the second diameter, wherein the first angle and the first diameter are less than the second angle and the second diameter to provide substantially uniform gas flow through the outlets; wherein the first arcuate channel extends less than 360° partially around the inner surface of the gas ring with two first channel ends spaced from one another and the second arcuate channel extends 360° around the inner surface of the gas ring.