Load Port Control for Semiconductor Substrate Handling
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Solution Overview
Problem
Conventional substrate treating systems face inefficiencies in using carrier transport systems due to issues with loading and unloading intervals, leading to wasteful circulating movements and resource underutilization when multiple vehicles attempt to load or unload pods simultaneously at a shared load port.
Innovation Solution
Implementing a substrate treating system with an internal buffer and advanced control units that manage loading and unloading processes, suspending transfer approvals until completion and reporting readiness for unloading early, and utilizing virtual load ports to allow multiple vehicles to access a single physical load port efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a movable buffer is provided to temporarily displace FOUPs from the load port, then the load port can be vacated for receiving the next FOUP, but when multiple OHTs consecutively carry FOUPs to the same load port, the loading intervals are too short and the next OHT may attempt and fail to load, causing the OHT to move along the circulating track and waste time
Solution Approach 1:
The control unit suspends the notice of transfer disapproval until completion of the current pod transfer, allowing the next OHT to wait in position rather than completing a full circulating track loop. This preliminary suspension of the disapproval notice prevents the time-wasting circulating movement while maintaining proper transfer sequencing.
Solution Approach 2:
The system uses feedback from the load port status and transfer completion signals to dynamically control the notice of transfer disapproval. The control unit receives feedback about ongoing transfers and adjusts the disapproval timing accordingly, preventing premature loading attempts and the associated wasteful circulating movements.
2Productivity
If the carrier transport system uses short loading intervals to maximize resource utilization, then more pods can be transported per unit time, but multiple vehicles may attempt to load or unload simultaneously causing loading failures and wasted circulating movements
Solution Approach 1:
The system dynamically adjusts the transfer disapproval timing based on real-time load port status. The notice of transfer disapproval is suspended until completion of the current transfer operation, creating a dynamic control mechanism that adapts to the actual state of the load port and prevents loading failures while maintaining high throughput.
Solution Approach 2:
The control unit acts as an intermediary between the carrier transport system and the load port, mediating the transfer disapproval notices. It receives information about ongoing transfers and controls the timing of disapproval notices to subsequent OHTs, ensuring that loading attempts are coordinated and successful.
Data Source
AI summary
A substrate treating apparatus having a substrate treating unit, a load port for receiving pods for storing the substrates, and transferring the pods to and from the substrate treating unit, and a buffer between the substrate treating unit and the load port for transferring the substrates to and from the substrate treating unit and the load port, and temporarily storing the pods; a carrier transport system for transferring the pods to and from the load port; and a host computer for transporting the pods in response to conditions. A transport-related control unit, when the load port is being used by one of the pods and a vehicle of the carrier transport system approaches to transfer another of the pods to the load port, to suspends a notice of transfer disapproval until completion of the use by the one of the pods.