Bare Wafer Stocker IO Buffer Layout for Throughput Continuity
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Solution Overview
Problem
In semiconductor manufacturing and other processes, the uniform flow of workpieces such as wafers and LCDs is hindered by equipment failures, maintenance delays, and storage inefficiencies, leading to accumulation and increased wait times in storage stockers.
Innovation Solution
An IO buffer system is introduced for automatic material handling, pre-assembling wafer carriers and providing independent storage to ensure continuous facility operation, even during stocker failures, with a scalable configuration that includes 2D linear arrays of shelves and a center linear robot handling assembly for efficient storage and retrieval of workpieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If workpieces are stored in a conventional stocker, then storage capacity is provided, but throughput is reduced due to slow response time and equipment downtime
Solution Approach 1:
The buffer stations pre-assemble wafer carriers and stage them for immediate transfer to the automatic carrier transport system. This preliminary preparation eliminates waiting time when the stocker is down or during normal operation, as carriers are ready to be transferred instantly rather than assembled on-demand from stored wafers.
Solution Approach 2:
The buffer stations serve as intermediary storage between the stocker and the automatic carrier transport system. This intermediate buffer decouples the slow stocker response from the fast transport system, allowing the transport to maintain high throughput even when the stocker is unavailable, while the buffer holds pre-prepared carriers.
2Speed
If workpieces are stored without carrier boxes in a bare stocker, then access speed is improved, but the system becomes vulnerable to downtime and requires complex handling
Solution Approach 1:
Wafer carriers are pre-assembled and staged in buffer stations before being transferred to the automatic carrier transport. This preliminary assembly ensures that when carriers are needed, they are immediately available in ready-to-transport form, maintaining fast access while ensuring system continuity during stocker downtime.
Solution Approach 2:
The buffer stations provide a cushion of pre-assembled carriers that protects the system against stocker failures or delays. This beforehand preparation ensures that the automatic carrier transport can continue operating at full speed even when the stocker is down, as the buffer contains a reserve of ready carriers.
3Ease of manufacture
If conventional stocker configurations are used, then simple storage is provided, but scalability and storage density are limited
Solution Approach 1:
The stocker uses vertical shelving arrays with shelves extending in multiple dimensions rather than simple horizontal stacking. This three-dimensional configuration dramatically increases storage density within the same footprint while maintaining robotic accessibility through the center linear robot that travels along rails to service shelves from the center.
Solution Approach 2:
The storage system is segmented into multiple independent shelves and buffer stations that can be serviced independently. The center linear robot can access any shelf segment without moving other segments, allowing parallel operations and maintaining simplicity while achieving high density through modular segmentation.
Data Source
AI summary
A buffer station for automatic material handling system can provide throughput improvement. Further, by storing to-be-accessed workpieces in the buffer stations of an equipment, the operation of the facility is not interrupted when the equipment is down. The buffer station can be incorporated in a stocker, such as bare wafer stocker.