A lid assembly for a semiconductor processing system is provided. The lid assembly generally includes a lid having first and second opposed surfaces, a plurality of controllable flow channels extending from the first and second opposed surfaces and a gas control system disposed on the first surface and operably opening and closing the channels. The gas control system includes a gas manifold disposed on the lid, at least one valve coupled to the gas manifold and adapted to control a flow through one of the flow channels, a reservoir fluidly connected to the gas manifold, and a precursor source fluidly connected to the reservoir.