A method and apparatus that includes a processing chamber that includes a showerhead with separate inlets and channels for delivering separate processing gases into a processing volume of the chamber without mixing the gases prior to entering the processing volume is provided. The showerhead includes one or more cleaning gas conduits configured to deliver a cleaning gas directly into the processing volume of the chamber while by-passing the processing gas channels. The showerhead may include a plurality of metrology ports configured to deliver a cleaning gas directly into the processing volume of the chamber while by-passing the processing gas channels. As a result, the processing chamber components can be cleaned more efficiently and effectively than by introducing cleaning gas into the chamber only through the processing gas channels.