MULTIPLE LEVEL SHOWERHEAD DESIGN

Embodiments of the present invention generally provide a showerhead assembly made of multiple plates fastened together. The showerhead assembly includes a gas manifold defined by a top and middle plate and a diverter plate defined by the middle plate and a bottom, heat exchange plate. A first processing gas enters the gas manifold and is diverted by the diverter plate through the bottom plate. A second processing gas enters the gas manifold and is diverted by the diverter plate through the bottom plate such that the second and first processing gases do not mix prior to exiting the showerhead. In one embodiment, the first processing gas can be distributed through central and outer regions of the showerhead at different flow rates and/or pressures. In addition, the second processing gas can be distributed through the central and outer regions of the showerhead at different flow rates and/or pressures.