An EFEM useful for transferring wafers to and from wafer processing modules comprises an enclosure having a controlled environment therein bounded by a front wall, a back wall, first and second side walls, a top wall, and a bottom wall. The first side wall and the second side wall include two or more wafer load ports wherein each wafer load port is adapted to receive a FOUP. The front wall includes wafer ports configured to attach to respective load locks operable to allow a wafer to be transferred to a front wall cluster processing tool. The back wall includes a wafer port adapted to be in operational relationship with a back wall cluster processing tool. A robot in the EFEM enclosure is operable to transfer wafers through the wafer load ports, the first front wall wafer port, the second front wall wafer port, and the back wall wafer port.