Scheduling of Single-Arm Cluster Tools for an Atomic Layer Deposition Process With Residency Time Constraints
针对半导体制造中原子层沉积工艺的晶圆重入问题，研究了单臂集群工具在驻留时间约束下的调度，首次推导了可调度性条件并提出了高效的最优调度算法。
In semiconductor manufacturing, there are wafer fabrication processes with wafer revisiting. Some of them must meet wafer residency time constraints. Taking atomic layer deposition (ALD) as a typical wafer revisiting process, this paper studies the challenging scheduling problem of single-arm cluster tools for the ALD process with wafer residency time constraints. It is found that there are only several scheduling strategies that are applicable to this problem and one needs to apply each of them to decide whether a feasible schedule can be found or not. This work, for each applicable strategy, performs the schedulability analysis and derives the schedulability conditions for such tools for the first time. It proposes scheduling algorithms to obtain an optimal schedule efficiently if such conditions are met. It finally gives illustrative examples to show the application of the proposed concepts and approach.