Embodiments of an apparatus for gas delivery in a semiconductor processing system use a gas distribution plate that has a plurality of gas passageways where the passageways have surfaces with an average roughness of less than or equal to approximately 10 Ra. In some embodiments, the gas distribution plate has one or more internal fluid passageways that are capable of being fluidly coupled to one or more fluid sources to provide temperature control of the gas distribution plate. In some embodiments, the gas distribution plate has at least one internal cavity with at least one heatsink that may surround at least one of the plurality of gas passageways to provide, at least partial, temperature control of the gas distribution plate.