Multi-Level OHT Rail System for Semiconductor Tool Integration
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Solution Overview
Problem
Single level rail designs for overhead transport systems in semiconductor manufacturing face challenges such as increased footprint, decreased speed, and inability to keep up with high throughput tools, especially when expanding to accommodate additional process and inspection tools.
Innovation Solution
Implementing a multi-level rail system where OHT vehicles move workpieces along first and second rails, with a storage buffer in between, allowing for efficient transfer and utilization of high throughput tools while maintaining a compact footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single level rail design is used, then the system structure is simple, but the footprint increases and the speed decreases when expanding to accommodate additional tools
Solution Approach 1:
The patent transitions from a single-level rail system to a multi-level rail system, utilizing vertical space to accommodate additional process and inspection tools. This dimensional change allows the system to expand capacity without proportionally increasing the horizontal footprint, as rails are stacked at different elevations to serve multiple tools within the same floor space.
Solution Approach 2:
The multi-level rail system nests multiple rails vertically, with upper and lower rails positioned at different heights. This nesting arrangement allows the system to serve multiple tools simultaneously within a compact volume, effectively nesting the transport paths one above another to maximize space utilization.
2Ease of operation
If a single level rail design is used, then the system is easy to operate, but the transfer speed decreases when moving between rail loops
Solution Approach 1:
By moving the transport system into three-dimensional space with multiple vertical levels, the patent eliminates the need for lateral bridge traversals required in single-level systems. Workpieces can be transferred directly between tools at the same level or efficiently moved between levels via vertical transport, significantly reducing transfer time while maintaining operational simplicity through automated control.
3Productivity
If a single level rail design is used, then the device complexity is low, but the system cannot keep up with high throughput tools
Solution Approach 1:
The multi-level configuration increases throughput capacity by providing parallel transport paths and eliminating bottlenecks associated with single-level bridge traversals. Multiple rails at different levels can operate simultaneously, increasing the system's ability to handle high-volume tooling requirements, with the added complexity managed through automated control systems.
Solution Approach 2:
The rail system is segmented into multiple independent levels, each capable of autonomous operation. This segmentation allows different rail loops to function independently, enabling parallel processing and increasing overall system throughput. The modular structure facilitates easier maintenance and operation despite the increased system capacity.
Data Source
AI summary
An overhead transport (OHT) system with multiple levels of rails for the transport of semiconductor workpieces is provided. A first vehicle is configured to travel on, and move a semiconductor workpiece along, a first rail. A second vehicle is configured to travel on, and move the semiconductor workpiece along, a second rail overlying the first rail. A controller is configured to control the first and second vehicles to transfer the semiconductor workpiece along the first and second rails, between process or inspection tools. A method for transferring semiconductor workpieces across multiple levels of rails is also provided.