Gas distribution system for improving transient vapor phase deposition

Embodiments of the present invention are directed to a gas distribution system which distributes the gas more uniformly into a process chamber. In one embodiment, a gas distribution system comprises agas ring including an outer surface and an inner surface, and a gas inlet disposed at the outer surface of the gas ring. The gas inlet is fluidicly coupled with a first channel which is disposed between the outer surface and the inner surface of the gas ring. A plurality of gas outlets are distributed over the inner surface of the gas ring, and are fluidicly coupled with a second channel which isdisposed between the outer surface and the inner surface of the gas ring. A plurality of orifices are fluidicly coupled between the first channel and the second channel. The plurality of orifices arespaced from the gas inlet by a plurality of distances, and have sizes which vary with the distances from the gas inlet as measured along the first channel, such that the size of the orifice increaseswith an increase in the dis