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, resulting in 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 defining the relationship between places and transitions. Then, a control method by using self-loops is presented to prevent the model 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.
Highlights
In semiconductor manufacturing, cluster tools have been extensively used for wafer fabrication due to their flexibility, reconfigurability, and efficiency [36]
Since the number of process modules (PMs) in an single-arm cluster tool (SACT) and the number of wafers in a lot are limited, based on Theorem 3.1, as the Petri net model represented by (Ă‘SACT −C, M0, MF ) evolves, it can reach MF starting from M0 such that raw wafers can be processed in the tool and returned to the loadlocks one by one
A general Petri net model is defined for SACTs by determining the relationships between transitions and places
Summary
Cluster tools have been extensively used for wafer fabrication due to their flexibility, reconfigurability, and efficiency [36]. By using the existing methods, it is hard to generate a deadlock-free Petri net model for cluster tools within reasonable time For such a case, it is necessary to find a general method to resolve the deadlock problem of cluster tools with multiple wafer types being concurrently processed within reasonable time. This motivates us to do so for an SACT. Given the wafer flow patterns of all wafer types to be processed, a general definition is proposed to obtain such a Petri net model for an SACT.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
