Fab Capacity Simulations

This paper studies the operational logic in an inter-bay automated material handling system (AMHS) in semiconductor wafer fabrication. This system consists of stockers located in a two-floor layout. Automated moving devices transfer lots between stockers within the same floor (intra-floor lot transfer) or between different floors (inter-floor lot transfer).

This paper identifies a method for classifying a fab model by the level of capacity detail, the level of AMHS detail, or the level of capacity/AMHS detail. Within the capacity/ AMHS modeling level, our method further differentiates between detailed integrated capacity/AMHS models and abstract coupled capacity/AMHS models.

In this paper, AMHS productivity detractors affecting small lot manufacturing are studied, including the track layout, number of vehicles, empty vehicle management rules, number of stockers, stocker capacity, among others.

This paper is one of the first papers to discuss the applications of conveyors for automated material handling system (AMHS) in semiconductor wafer fabs. More specifically, a queueing-based analytical model is proposed for designing a closed-loop conveyor-based AMHS.

This paper proposes several heuristics to optimize the location of crossovers in a conveyor-based AMHS for semiconductor wafer fabs. The heuristics determine the locations of special conveyor path segments (cross overs) to minimize relevant capital and operating costs.