US Patent 9728380 Dual-plenum showerhead with interleaved plenum sub-volumes

Apparatuses and techniques for providing for variable radial flow conductance within a semiconductor processing showerhead are provided. In some cases, the radial flow conductance may be varied dynamically during use. In some cases, the radial flow conductance may be fixed but may vary as a function of radial distance from the showerhead centerline. Both single plenum and dual plenum showerheads are discussed.