A two piece ceramic showerhead includes upper and lower plates which deliver process gas to an inductively coupled plasma processing chamber. The upper plate overlies the lower plate and includes radially extending gas passages which extend inwardly from an outer periphery of the upper plate, axially extending gas passages in fluid communication with the radially extending gas passages and an annular recess forming a plenum between the upper and lower plates. The lower plate includes axially extending gas holes in fluid communication with the plenum. The two piece ceramic showerhead forms a dielectric window of the chamber through which radiofrequency energy generated by an antenna is coupled into the chamber. The gas delivery system is operable to supply an etching gas and a deposition gas into the processing chamber such that the etching gas in the plenum can be replaced with the deposition gas.