Due to the process characteristics and the complexity of the process flow, the wafer fabrication in semiconductor manufacturing is difficult to schedule using the methods applicable to other manufacturing systems. This thesis sets the flow time and the throughput rate as control targets, and proposes a real-time scheduling methodology including unexpected events such as machine breakdown and repair, etc. This thesis also presents a GSPN (generalized stochastic Petri nets) modeling and performance analysis of the wafer fabrication.
The scheduling of the wafer fabrication consists of sequence control and input release control, the former for selecting a cassette to be processed in the available machine, the latter for determining the type and the time of a cassette to be released into wafer fab. In this thesis, OPNDD (operation due date) Rule and Regulation of the Buffer Length are used for the sequence control. Pre-Simulation and Feedback Control are used for the input release control. Pre-Simulation and Feedback Control are used for the input release control.