Load Lock Secondary Isolation Chamber for Wafer Processing
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Solution Overview
Problem
Traditional multi-wafer load lock systems face challenges in processing a single wafer for auxiliary tasks without exposing the remaining wafers to the ambient environment, leading to contamination and reduced throughput due to frequent pressure changes and port openings.
Innovation Solution
A load lock apparatus with a secondary isolation chamber, featuring a partition that separates the chamber into upper and lower portions, allowing for selective processing and handling of wafers while maintaining a particle-free environment, enabling auxiliary processes like cleaning and metrology without exposing all wafers to the ambient environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wafer is removed from the load lock for auxiliary processing, then the wafer can undergo cleaning, testing or other auxiliary processes, but the entire load lock must be brought to atmospheric pressure and the port opened, exposing all wafers to the ambient environment and introducing particulates
Solution Approach 1:
The load lock chamber is divided into two separate chambers by a partition wall with a port. This segmentation allows one chamber to be isolated for auxiliary processing while the other chamber maintains its vacuum environment, enabling selective access without exposing all wafers to ambient contamination.
Solution Approach 2:
The problematic function of atmospheric pressure equalization and port opening is extracted from the main load lock chamber and applied only to the auxiliary processing chamber. This allows auxiliary processing to occur in isolation, removing the harmful effect of exposing the entire wafer batch to ambient particulates.
2Ease of operation
If the load lock is backfilled and re-evacuated every time a wafer is removed for auxiliary processing, then the wafer can be accessed for processing, but the throughput of wafers is reduced due to the time-consuming pressure cycles
Solution Approach 1:
By segmenting the load lock into two independent chambers, the system enables parallel operations where auxiliary processing can occur in one chamber while the other chamber maintains its vacuum state and continues wafer processing, thereby eliminating throughput reduction caused by full chamber pressure cycles.
Solution Approach 2:
The auxiliary processing chamber is prepared and isolated in advance with its own pressure control system, allowing wafers to be transferred for auxiliary processing without requiring the main chamber to undergo time-consuming backfill and evacuation cycles, thus maintaining high throughput.
3Ease of operation
If the port is opened to remove a wafer for auxiliary processing, then the wafer can be transported to an off-line tool, but all wafers in the load lock are exposed to the ambient environment which is detrimental to processing quality
Solution Approach 1:
The partition wall with a dedicated port creates a segregated auxiliary processing chamber that can be opened to the ambient environment independently. This allows easy wafer transport to off-line tools while the main chamber remains sealed and maintains its controlled atmosphere, protecting processing quality.
Solution Approach 2:
The harmful exposure to ambient environment is extracted and confined only to the auxiliary processing chamber during port opening. The main chamber's controlled atmosphere is preserved, ensuring that processing quality of wafers remaining in the main chamber is not compromised.
Data Source
AI summary
A load lock includes a chamber including an upper portion, a lower portion, and a partition between the upper portion and the lower portion, the partition including an opening therethrough. The load lock further includes a first port in communication with the upper portion of the chamber and a second port in communication with the lower portion of the chamber. The load lock includes a rack disposed within the chamber and a workpiece holder mounted on a first surface of the rack, wherein the rack and the workpiece holder are movable by an indexer that is capable of selectively moving wafer slots of the rack into communication with the second port. The indexer can also move the rack into an uppermost position, at which the first surface of the boat and the partition sealingly separate the upper portion and the lower portion to define an upper chamber and a lower chamber. Auxiliary processing, such as wafer pre-cleaning, or metrology can be conducted in the upper portion.