Heuristic based scheduling system for diffusion in semiconductor manufacturing

This paper addresses the scheduling of lots in a specific wafer fabrication area, called diffusion, where scheduling of lots interact with batching, equipment dedication and queue time constraints. Realizing the difficulty of solving the underlying mathematical program optimally, we develop a heuristic to regularly schedule the lots available in the area in real time. The paper explains the user interface and implementation issues as well as the details of the heuristic logic. The results obtained from production in a wafer fabrication facility to date show high user compliance, improved predictability and visibility of the overall schedule, and improved operational performance including reduced cycle times and queue time violations.