Abstract: A semiconductor device fabrication system comprises a central hub area and multiple concentric ring sections circumferentially provided around the hub area. Each of the ring sections has a plurality of modular process units (MPUs) each receiving about three in-line semiconductor device processing stations therein and having the size of a standard shipping container for conveniently outgoing heavy repair. The MPUs are successively disposed around the hub area with the walls positioned radially of the hub area. Service facilities and handling piping system are provided under the MPUs. Each of the ring sections has a conveying track provided adjacent to the ring-shaped arranged MPUs for communication with the MPUs. A human maintenance system is provided in the system for carrying service persons to get into and out of the MPUs through the sidewalls thereof for light repair.