Abstract: In some embodiments, a gas distribution apparatus includes a first plate having a plurality of ports disposed through the first plate; a second plate disposed above and coupled to the first plate; a third plate disposed above and coupled to the second plate; a first plenum disposed between the first plate and the second plate and fluidly coupled to a first set of the plurality of ports, wherein the first plenum comprises a gas supply coupled to the first plenum to provide a process gas to an area proximate a substrate via a first set of the plurality of ports; a second plenum disposed between second plate and the third plate and fluidly coupled to the second set of ports, wherein the second plenum comprises a vacuum applied to the second plenum to remove reaction byproducts from the area proximate the substrate via a second set of the plurality ports.