A method of etching a wafer includes injecting a source gas mixture into a process chamber. The injecting includes injecting the source gas into multiple hollow cathode cavities in a top electrode, generating plasma in each of the cavities, and outputting the plasma from corresponding outlets of the cavities into a wafer processing region in the chamber, where the processing region is located between the outlets and a surface to be etched. An etchant gas mixture is injected into the processing region through injection ports in the top electrode such that the etchant gas mixes with the plasma output from the outlets. The etchant gas is prevented from flowing into the outlets of the cavities by the plasma flowing from the outlets. Mixing the etchant gas and the output from the cavities generates a desired chemical species in the processing region and thereby enables the surface to be etched.