Development of a Real-Time Scheduling and Rescheduling System based on RFID for Semiconductor Foundry Fabs
Date Issued
2005
Date
2005
Author(s)
Tsai, Chiao-Ju
DOI
en-US
Abstract
In the fab planning, how to achieve a fully automated manufacturing to replace human operator in performing runtime scheduling and dispatching decisions is a very important issue. This thesis constructs a real-time scheduling and rescheduling system based on a new technology, RFID (Radio Frequency Identification), for fully automated fabs. The scheduling and rescheduling system consists of three modules: a real-time decision-making scheduler, a rescheduling mechanism for machine breakdowns and bottleneck, and a simulation platform for flexible manufacturing system (FMS).
In order to develop a real-time decision-making scheduler, we use RFID to collect system attributes and choose the salient attributes by GA based FFEI (Genetic Algorithm based Fuzzy-entropy-based Feature Evaluation Index). Then, the salient attributes corresponds to dispatching rules by using support vector machine (SVM). The proposed rescheduling framework is used when unknown machine breakdowns and bottleneck happen. We define the bottleneck tools with utilization of machines or queuing length, and then implement the rescheduling strategies. Next, we develop the simulation platform by using object-oriented software, eM-Plant.
The implemented scheduling and rescheduling system have been demonstrated by two example manufacturing models, a 300mm factory fab of SEMATECH and TRC fab. In SEMATECH model, the mean flow time is reduced 3%(203.32－＞197.307 hours) and tardy numbers are decreased 17% (63－＞52 lots). We also have more throughput (176852－＞177951 wafer). In TRC fab model, the mean flow time is reduced 4% (451.23－＞427.86 hours) and tardy numbers are decreasing 25% (15－＞12 lots).
The experimental results of simulation are better than previous researches. The dispatching rule sets proposed by SVM scheduler have higher performance than single dispatching rule. This scheduling and rescheduling framework can consider time of machine breakdowns and bottleneck and improve the system immediately.
Subjects
晶圓廠
排程
RFID
Semiconductor Foundry Fabs
Scheduling
Rescheduling
Type
thesis