Many semiconductor processing operations are performed within sealed semiconductor processing chambers in which a semiconductor wafer or other substrate is supported on a wafer support or pedestal underneath a gas distributor, commonly referred to as a “showerhead.” Discussed herein are a new type of showerhead design for use in semiconductor processing equipment, in particular, in semiconductor processing equipment in which there may be sequential flows of multiple different types of semiconductor processing gasses, as is the case in atomic layer deposition (ALD) and other processes.