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 upper plate can include eight radially extending gas passages evenly spaced around the periphery of the upper plate and the lower plate can include inner and outer rows of gas holes. 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. A gas delivery system delivers process gas to a plenum between the upper and lower plates having a gas volume of no greater than 500 cm3. The gas holes in the lower plate extend between the plenum and a plasma exposed yttria coated surface of the lower plate. 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 within about 200 milliseconds and vice versa.