Plasma etch system

Disclosed is a system, including both method and apparatus, for enhancing the plasma etching of a semiconductor wafer. The system enhances etchant uniformity while greatly reducing plasma contamination. Etching is performed in a housing for processing a semiconductor wafer having a wafer perimeter defined by an outer wafer edge, a top surface and a bottom surface. The plasma etch technique includes a plasma positioned substantially coplanar with and proximate,to the semiconductor wafer. The plasma has a perimeter defined by an outer plasma edge and extending beyond substantially all of the wafer perimeter. Provided is a means for introducing an inert gas between the wafer perimeter and the plasma perimeter so the inert gas may or may not hit the wafer's bottom surface. Plasma and wafer can each have a circular shape where the plasma and the wafer are proximate to each other. Further provided can be a plasma focussing device having an inner wall residing beside and encircling that portion of the plasma overlying the wafer, the device positioned coaxially with the wafer and having a diameter larger than the wafer diameter.