Real-Time Scheduling of Single-Arm Cluster Tools Subject to Residency Time Constraints and Bounded Activity Time Variation

• Published in: IEEE transactions on automation science and engineering Vol. 9; no. 3; pp. 564 - 577
• Main Authors: Qiao, Yan, Wu, NaiQi, Zhou, MengChu
• Format: Journal Article
• Language: English
• Published: Piscataway, NJ IEEE 01.07.2012; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Applied sciences; Automation; Cluster tools; Computer science; control theory; systems; Control system analysis; Control theory. Systems; discrete event system; Discrete event systems; Electronics; Exact sciences and technology; Microelectronic fabrication (materials and surfaces technology); Petri net (PN); Petri nets; Real time; Real-time systems; Robots; Scheduling; Semiconductor device manufacture; Semiconductor device modeling; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; semiconductor manufacturing; Cluster tools; Minimization; Scheduling; Real time; Modeling; Microelectronic fabrication; Petri net (PN); Indirect method; Off line; semiconductor manufacturing; Tool management; Arm; Petri net; Discrete event system
• ISSN: 1545-5955; 1558-3783
• DOI: 10.1109/TASE.2012.2192476

It is very challenging to schedule cluster tools subject to wafer residency time constraints and activity time variation. This work develops a Petri net model to describe the system and proposes a two-level real-time scheduling architecture. At the lower level, a real-time control policy is used to offset the activity time variation as much as possible. At the upper level, a periodical off-line schedule is derived under the normal condition. This work presents the schedulability conditions and scheduling algorithms for an off-line schedule. The schedulability conditions can be analytically checked. If they are satisfied, an off-line schedule can be analytically found. The off-line schedule together with a real-time control policy forms the real-time schedule for the system. It is optimal in terms of cycle time minimization. Illustrative examples are given to show the application of the proposed approach. Note to Practitioners-This paper discusses the real-time scheduling problem of single-arm cluster tools with wafer residency time constraints and bounded activity time variation. With a Petri net model, schedulability is analyzed and schedulability conditions are presented by using analytical expressions. Then, an efficient algorithm is proposed to find a periodical schedule if it is schedulable. Such a schedule is optimal in terms of cycle time and can adapt to bounded activity time variation. Therefore, it is applicable to the scheduling and real-time control of cluster tools in semiconductor manufacturing plants.