Modeling and Control for Deadlock-Free Operation of Single-Arm Cluster Tools With Concurrently Processing Multiple Wafer Types via Petri Net

Abstract

Nowadays, cluster tools tend to concurrently process multiple types of wafers with similar recipes in order to improve their utilization and flexibility in semiconductor manufacturing. Different wafer types may have different wafer flow patterns such that cluster tools are deadlock-prone. It is challenging to develop a general method to solve the deadlock problem of cluster tools without restriction on the wafer types. This work aims at solving such a challenging problem for single-arm cluster tools. To do so, a general Petri net model is developed for single-arm cluster tools. Given the wafer flow patterns of all wafer types to be processed in a single-arm cluster tool, such a Petri net model can be easily obtained by a proposed general definition. Then, a control method by using self-loops is presented to prevent the obtained Petri net from deadlocks during the evolutions from the initial state to the final state. Furthermore, such a control method is proved to be optimal. Illustrative examples are given to verify the proposed method at last.

Influence of Dynamic Accuracy Constraints of Manipulator of Wafer Transmission Robot on Scheduling and Control of Single-Armed Cluster Tools

“…Cluster tools are highly automated and integrated equipment that are broadly applied in wafer fabrication processes [13], [14]. To effectively improve the production efficiency and yield rate of wafers, many scholars have extensively investigated these problems regarding the scheduling and control of single-armed cluster tools with different constraints.…”

“…where ω is the natural frequency of the torsional vibration system of manipulator. According to (13), the natural frequency of the i-order mode of the torsional vibration system, that is ω i (i = 1, 2, 3), can be calculated. The modal transfer matrix of the torsional vibration system and the i-th order modal coordinate vector corresponding to , that is A (i) (i = 1, 2, 3), can be determined by using (13).…”