Semiconductor wafer fabrication is a challenging
technological process in this world. The cost of
equipment is about 80% of the factory capitalcosts .
This type of process is highly reentrant and creates a
large amount of material flow between bays (inter- or
intrabay movement). The increasing demand for ultraclean
areas of semiconductor fabrication is leading to
the automated materialhandl ing and control. The main
purpose of an automated materialhandl ing system
(AMHS) is to improve the performance of the overall
fabrication process, by reducing manufacturing cycle
time and increasing equipment use. This improvement
comes by optimizing materialdel iveries to the required
areas during the fabrication cycle.