A plasma processing apparatus includes a gas distribution member which supplies a process gas and radio frequency (RF) power to a showerhead electrode. The gas distribution member can include multiple gas passages which supply the same process gas or different process gases at the same or different flow rates to one or more plenums at the backside of the showerhead electrode. The gas distribution member provides a desired process gas distribution to be achieved across a semiconductor substrate processed in a gap between the showerhead electrode and a bottom electrode on which the substrate is supported.