Overhead Hoist Transport System Trident Rail Configuration
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Solution Overview
Problem
Conventional overhead hoist transport systems in semiconductor fabrication plants face inefficiencies in clean room space utilization and transfer efficiency due to rigid track configurations, leading to wasted space and increased travel times for wafers, which hampers productivity.
Innovation Solution
The design of an overhead wafer transport system featuring a trident-like rail configuration with a main track and two lateral tracks, allowing the shuttle to selectively travel along the main or lateral tracks, optimizing space usage and reducing travel distances by enabling more efficient routing of wafers between production tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the OHT rail is arranged in a conventional Y-shaped configuration with main track and lateral track, then the shuttle can transport wafers between production tools, but the shuttle has to go round the production tool to transport wafers, resulting in increased travel distance and reduced transfer efficiency
Solution Approach 1:
The OHT rail is segmented into a main track and two separate lateral tracks that are independently connected to the main track. This segmentation allows the shuttle to choose different routing paths (main track or lateral tracks) depending on the destination, enabling direct transport without unnecessary detours around production tools.
Solution Approach 2:
The system provides dynamic routing capability where the shuttle can selectively travel along different track configurations. The track-interface assembly allows the shuttle to switch between the main track and lateral tracks based on operational needs, optimizing the transport path in real-time to minimize travel distance and time.
2Productivity
If the OHT rail position is fixed in conventional configurations, then the track structure is simple, but the clean room space utilization is poor and more clean room expansion is needed to accommodate additional production tools
Solution Approach 1:
The OHT rail utilizes the overhead three-dimensional space by positioning tracks at elevated levels rather than occupying floor space. The main track and lateral tracks are arranged in a spatial configuration that maximizes vertical space utilization, allowing production tools to be placed on the floor plane below without conflict, thereby improving overall clean room space utilization.
Solution Approach 2:
The OHT rail configuration with main track and two lateral tracks provides multi-functional routing capability that can serve multiple production tools simultaneously. The track system is designed to accommodate various tool placements and transport scenarios, making the overhead structure a universal solution that maximizes the utility of available clean room space.
3Device complexity
If the lateral track is connected to the main track through the side, then the track structure is compact, but the shuttle travels a longer distance and transfer efficiency is reduced
Solution Approach 1:
The lateral tracks are asymmetrically connected to the main track through dedicated track-interface assemblies positioned at optimal locations. This asymmetric configuration allows the shuttle to access lateral tracks directly from the main track without symmetric detours, creating more efficient one-way or optimized bidirectional flow paths that reduce travel distance while maintaining structural compactness.
Data Source
AI summary
An overhead wafer transport system includes an over head transportation (OHT) rail and at least one shuttle. The OHT rail includes a main track and two lateral tracks, each having a hollow transverse cross-section, each lateral track being in corresponding connection with the main track through the two sides thereof, constituting an approximate tri-directional branch form. The shuttle has a track-interface assembly and a docking unit, the track-interface assembly being adapted to travel along the OHT rail. The track-interface assembly being arranged at the junction of the two lateral tracks and the main track, wherein the track-interface assembly is adapted to selectively travel along at least one of the main track and the lateral tracks. Therefore, the overhead wafer transport system can be applied to a clean room with higher transfer efficiency and clean room space utilization.