Developing a fuzzy-set-based shortcut layout approach for a semiconductor inter-bay handling system

Abstract

Designing optimal material flow into a semiconductor inter-bay handling’s layout boosts production efficiency, increases yield and throughput, and cuts work-in-process (WIP) as well as cycle time. Intelligent layout of production plants is vital for modern manufacturing, and particularly so for 450-mm wafer-size semiconductor plants. In light of the particular bay nature of a semiconductor plant’s inter-bay, its shortcut design that results on more efficient flow movement become challenging differed from those of a manufacturing system. Additionally, a semiconductor bay’s shortcut layout considerations must address not just how to group stockers, but also how to determine the type of shortcut points and sequence of shortcut locations. Prior to mass production, the assessment expressed by designers’ artificial language, linguistic variable, for the shortcut design phase remains ambiguous and subjective. The need for efficient ways to take designers’ linguistic variables into account in the layout decision increases. The present study suggests a method based on fuzzy set theory to design the shortcut location for a semiconductor inter-bay equipped with a multiple-zone overhead shuttle (OHS) handling system. Unlike traditional layout approaches which can only handle quantitative data with Boolean logic problems, fuzzy-set-based methods offer a way to incorporate the attitude of designers using linguistic variables to represent a problem in decision making when designing semiconductor bay’s shortcut layout. The paper also develops an intelligent hybrid heuristic algorithm incorporating with the goal of maximizing in-sequence movements and minimizing total flow distance to search a better shortcut layout design. An illustrative example from a wafer foundry company is used to demonstrate that the fuzzy-set-based layout design found by the proposed layout method outperforms by other approaches in the OHS travel time, throughput, and flow time performance. The method suggested here can assist semiconductor facility designers in qualitatively and quantitatively improving the material flow and increasing production efficiency by solving their semiconductor bay’s shortcut layout problems.