A substrate processing system as illustrated at (1). A substrate (2) lies upon a piston (3) shown in both the loading position (3a) and in a processing position (3b). The substrate is loaded via a port (4) through a door (5). The loading area (7a), and/or the hole chamber (7) may be pumped out via a vacuum exhaust pipe (6) connected to a pump (not shown). A linear drive mechanism shown diagrammatically at (8) lifts the piston and the substrate in the chamber such that a process volume (7b) of the chamber is defined with poor gas conduction between the piston and the walls of the chamber.