Unified fab solution
Traditional design of AMHS segmented the transport system into local cell (or intra bay) transport, and inter cell (or inter bay) transports. The vehicles transiting the local cells remained in that space, and the WIP was passed on to an inter bay system via a stocker interface, if move out of the cell was required. Theoretically, a direct move from tool to tool was desired (via a transit through inter bay, but without the WIP changing vehicles). But to date unobtainable, except for low flow capacities. The concept called for a unified transport system fab wide.
With conveyor systems this is a natural design and much experience is available for the direct tool to tool work flow on a unified conveyor network. Small in line buffers are arranged at the source and destination of such WIP moves.