Research On Scheduling Of Batch Processing Machines In Semiconductor Wafer Fabrication System

The batch processing machine?BPM?of semiconductor wafer fabrication system?SWFS?has lots of complex characteristics,such as multi-re-entrant processing flow,high uncertainties.It belongs to a bottleneck machine in SWFS.There are two kinds of BPM types:one is that a single processing machine is followed by a BPM?i.e.,it is denoted as????,the other is that one BPM is followed by another BPM?i.e.,it is denoted as?₁??₂?.It is obvious that a good scheduling decision of BPM is beneficial to improve performance of the whole SWFS.The major contents of this thesis consist of batch sequencing of the???type,batch regrouping and sequencing of the?₁??₂ type,batch assigning of parallel BPMs.The research methods and results are listed as follows.?1?Re-entrant family-oriented?sequencing in the???typeIn order to use the re-entrant characteristic of BPM in SWFS,this thesis proposes a method of re-entrant family-oriented?scheduling in the???type.On one hand,this method can solve the serious disadvantage of batch-oriented?scheduling method.On the other hand,different re-entrant families can be given different priority weights.It is suitable for the real requirement of SWFS.As for high uncertainties and real production control of releasing on wafer and delivering on week in SWFS,this thesis proposes a method of?batch sequencing with due window in the???type.This method can avoid the serious disadvantage that the high uncertainties affect?batch sequencing with due date point.The products always can't be delivered on-time at the due point.Moreover,it is suitable for the real requirement of SWFS,too.For the?scheduling algorithms in the???type,the research results include re-entrant family-oriented batch sequencing through both slack-based mixed integer linear programming model with due date point and the model with distinct due window.?2?Unifying?₂ batch regrouping and sequencing in the?₁??₂ type by a unified modelThe batch regrouping is a special procedure for?₂ scheduling in the?₁??₂ type.This thesis proposes a?₂ scheduling method to unify batch regrouping and sequencing in one model.Not only it meets the conditions of model complexity,but also it does not pass data between batch regrouping and batch sequencing,which can improve efficiency.The research result is the batch regrouping and sequencing through a combined slack-based mixed integer linear programming model for the?₂ scheduling.?3?Re-entrant family-oriented batch assigning of parallel BPMsIn the parallel BPMs area,the number of identical machines maybe more than one,this thesis studies batch assigning of parallel BPMs,which is based on pull and push strategies.As different job families of the batch regrouping of the?₁??₂ type are compatible,different regrouping batches are regarded as single re-entrant family.The?₂ batch assigning problem in the?₁??₂ type is an exception of the?batch assigning problem in the???type with single re-entrant family.The research result is the re-entrant family-oriented closed loop control batch assigning algorithm for the parallel BPMs.The above scheduling models and algorithms have been executed by the real-time scheduling simulation platform of SWFS,the standard commercial solver ILOG CPLEX and the program developed by ourselves.It can be found that our proposed methods can balance computation time and solution quality.