Optimization of diffusion batch size based on real-time information

• Main Author: Zhang, Chenru
• Other Authors: Wu Kan
• Format: Theses and Dissertations
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/54719
• Institution: Nanyang Technological University

Diffusion is one of the operations that are run on batching basis in semiconductor fabrication. Due to its long processing time and being non-pre-emptive, operators and supervisors on the shop floor are frequently facing the dilemma that whether to launch the next batch promptly with available lots to avoid idle time, or to wait for more lots to arrive so as to make better utilization of the equipment. Hence, the goal of the research is to derive a new control strategy to optimize the diffusion batch size based on real-time information in manufacturing system. Many similar efforts have been made to deal with the problem previously. Compared." to them, this research features a couple of improvements. First, it employs integer linear programming instead of heuristics to solve the problem so that the solution is guaranteed to be optimal. Second, move rate (throughput) is selected to be the objective function as it is a more practical KPI than the long-time used cycle time in prior research. Simulation results prove the new method to be productivity boosting under all traffic intensities. Compared to benchmark, the improvement is about 150/0 under low utilization, while 2-50/0 under medium to high. Recommendations for future study are provided at the end.