The development of a TOC-based dispatching rule for wafer fabrication

• Main Authors: Kai-chung Hou, 侯凱中
• Other Authors: Suhua Hsieh
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/34994335469430614319

碩士 === 國立臺灣大學 === 機械工程學研究所 === 89 === Abstract Advisor: Suhua Hsieh Student: Kai-chung Hou Dispatching rules and system performance evaluation factors affect system performance, and are both the important issues in the wafer fabrication system. The most important indicator for business success is profit, especially in short-lifetime semiconductor industries. Observed past researches that there is no dispatching rule based on profit developed for wafer fabs. Can those non-profit- based dispatching rules adopted in wafer fabs currently lead to the best profit or not? The main purpose of this study is to develop a profit-based dispatching rule by the theory of constraints (TOC) for wafer fabrication. In this study the present costs and values of the WIP wafers based on the consumption of system resources are estimated. The profitability of each WIP wafers is thus derived. By comparing their associated profitability of a time unit among all WIP wafer lots, the one with highest profitability is selected to be fabricated next. A profit-based dispatching rule named DTC (Dispatching by theory of Constraints) is therefore developed. The DTC is expected to lead the wafer fab system to the best profit by the increase of production response rate and the reduction of WIP inventory cost of those high profit wafers. For the purpose of the evaluation of the proposed DTC, a wafer fab simulation model is built in this study. Besides using DTC to dispatch jobs, MCR and MBS dispatching rules are adopted, respectively. Simulation results reveal that MCR and MBS do not have significant relationship with profit, while DTC does. Simulation results show that DTC speeds the production response rate of those high profit wafers 12%, and reduces the WIP inventory cost effectively.