Research On Anti-congestion Path Planning For The Unified AMHS In Wafer Fabrication System

Wafer fabrication is the most crucial stage in the semiconductor fabrication process.To effectively shorten the wafer production cycle,the 12-inch wafer fabrication system has been widely used in the wafer fabrication industry.The unified automated material handling system(AMHS)has gradually become a crucial part of the 12-inch wafer fabrication system due to its high handling efficiency,high safety and high reliability.There are large-scale wafer handling tasks and overhead hoist transport(OHT)in the unified AMHS,the OHT realizes the direct transport of wafers between different processing zones,congestion between OHTs occur frequently,which reduces the operational efficiency of the unified AMHS.How to reduce the OHT congestion to improve the operation efficiency of the unified AMHS has become a key problem to be solved urgently.Therefore,this paper takes the unified AMHS as the research object,and deeply studies the anti-congestion path planning method to improve the operation efficiency of the unified AMHS.The main contents are as follows:(1)A unified AMHS anti-congestion path planning method based on reinforcement learning.Aiming at the problem of OHT congestion in the unified AMHS,the causes and types of OHT congestion are analyzed.Considering the operation status information of the unified AMHS,the real time congestion index of the transport track is established.A real time data-driven reinforcement learning(RTDRL)based anti-congestion path planning method for the unified AMHS is proposed,this method constructs an action selection strategy based on real time congestion index and Q value to make path optimization decisions,and designs a reward function to improve the authenticity of Q value reflecting OHT traffic,to realize the dynamic adjustment of OHT handling path,the OHT congestion is reduced,and the unified AMHS operation efficiency is improved.Experiments based on the actual production data of a wafer fabrication workshop verify the feasibility and effectiveness of the proposed RTDRL method.(2)A unified AMHS dynamic path planning method considering loading and unloading area congestion.Aiming at the problem of OHT congestion in the loading and unloading area of the unified AMHS,the reasons for the congestion caused by the queuing of OHT in the loading and unloading area are further analyzed,and a dynamic path planning method for the unified AMHS considering congestion in loading and unloading area(CCLUA)is proposed.The method calculates the initial path-driving scheme according to the RTDRL method,and designs the strategy and method based on the operating state of OHT according to the operating condition information of the unified AMHS.The local dynamic adjustment of the OHT initial path driving scheme is realized,the congestion phenomenon in the loading and unloading area is reduced,and the unified AMHS operation efficiency is improved.Based on the actual production data of a wafer fabrication workshop,the experimental results show that the CCLUA method proposed in this paper is feasible and effective.(3)A unified AMHS anti-congestion path planning prototype system for wafer fabrication.Based on the proposed unified AMHS anti-congestion path planning method,a prototype system of the unified AMHS anti-congestion path planning for wafer fabrication was developed using Python language on the Py Qt5 platform.According to the actual production data of a wafer fabrication workshop,the main design functions of the prototype system are tested and analyzed to verify that the prototype system is feasible.The above research results can effectively reduce the generation of OHT congestion in the unified AMHS,and provide decision support for the path optimization and operation of OHT in the wafer fabrication workshop.It is of great significance to improve the operation efficiency of the unified AMHS,wafer production efficiency and workshop production management level.