A process chamber is disclosed which provides a 360.degree. circular gas/vacuum distribution over a substrate being processed. The substrate being processed is supported on a heated and optionally cooled pedestal assembly. The substrate faces a one-piece gas distribution faceplate being connected to an RF power supply outside the vacuum environment of the processing chamber. A pumping channel view port is provided to verify and confirm instrumentation readings concerning the degree of surface deposition on process chamber internal surfaces. All process chamber wall surfaces facing the region where plasma will be present during processing (except the gas distribution faceplate) are ceramic and therefore highly resistant to corrosion. The pedestal an un-anodized metal is also covered with a loosely fitting ceramic surface having alignment features to maintain concentricity between the wafer support surface of the pedestal and the wafer being processed. A valve body is contained within the wall of the processing chamber helping to reduce the surface area available for condensation of volatile process gas constituents which condense or cool in vacuum passage surfaces and can contaminate the process chamber if allowed to migrate back to it through the vacuum piping.