Method and apparatus for purging the back side of a substrate during chemical vapor processing

A processing system comprising:

• a process chamber;
• a support assembly within said process chamber which supports a substrate during processing;
• and
• a purge gas injector positioned below a backside of said substrate when the substrate is supported by said support assembly, said purge gas injector including an injector body having a central axis and including an internal conduit and an exit orifice in fluid communication with internal conduit, said exit orifice distributed around the circumference of the body and oriented to flow a purge gas supplied through the central conduit outward from the body into the process chamber in a range of substantially radial directions relative to the central axis.