<p>A plasma processing device is described which is modular and can be scaled up by assembly together with similar devices to provide a capability for large area processing. The device includes a housing which contains an array of RF coils and into which a process gas is fed. The article to be processed is disposed close to the housing and egress of the process gas from the housing to the process region is resisted so as to maintain a positive pressure differential between the housing and the process region. <IMAGE></p>