The layout design of semiconductor bays with spine and perimeter inter-bay guide path loops

In this paper, we study the bay layout problem in a semiconductor fab. One unique characteristic of this bay layout problem is that bays are connected by two inter-bay guide path loops - a spine guide-path loop and a perimeter guide-path loop. To ensure bays can be correctly arranged on the floor and connected by both guide path loops, this dual-loop guide path configuration must be considered throughout the entire layout design procedure. To achieve this goal, we propose a layout design method that considers not only the layout of bays, but also the layout of guide path loops. Furthermore, to ensure the feasibility and quality of the layout results, the proposed layout method solves these two layout problems simultaneously. Since semiconductor fabs often have shortcuts set up on their spine guide path loops, the problem of setting up shortcuts is also studied here. The objective of the proposed layout method is to minimise the total inter-bay flow distance of wafer cassettes. Heuristic methods and mathematical programming models are developed to assist us in achieving this objective. We solved an example problem to illustrate the proposed layout method. The example problem also demonstrates the capability of the proposed layout method in producing feasible and good-quality bay layouts with both spine and perimeter guide path loops.