Liquid Dispensing Valve Control to Prevent Wafer Process Drippage
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Solution Overview
Problem
Drippage during semiconductor wafer processing, caused by incomplete closure of automatic control valves, leads to reduced quality of integrated circuits due to liquid spills.
Innovation Solution
A liquid dispensing system with a main ACV retrofitted with a proxy sensor and a backup ACV, where a controller uses proxy signals from pressure sensors to ensure the backup ACV closes if the main ACV fails to fully shut, preventing drippage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single ACV is used to control liquid flow, then the device complexity is low, but the reliability deteriorates due to incomplete closure causing drippage
Solution Approach 1:
The patent implements a backup ACV that remains in standby mode to compensate for potential closure failures of the main ACV. This redundancy ensures that if the main valve fails to close completely, the backup valve can intervene to prevent drippage, thereby resolving the reliability issue without requiring the main valve to be overly complex
Solution Approach 2:
The patent introduces a proxy sensor as an intermediary element that indirectly measures the main ACV's closure status. This sensor acts as a mediator between the main valve and the backup valve, providing feedback information that enables the backup valve to activate only when needed, thus maintaining reliability while avoiding constant operation of multiple valves
2Measurement precision
If a proxy sensor is added to monitor ACV position, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The proxy sensor serves as an intermediary measurement device that indirectly assesses the main ACV's closure status without requiring direct contact with the valve mechanism. This approach provides sufficient measurement precision to detect closure failures while avoiding the complexity of direct position sensing systems
Solution Approach 2:
The patent replaces direct mechanical position sensing with an indirect measurement approach using the proxy sensor. This substitution reduces mechanical complexity while maintaining the ability to detect valve closure status and trigger the backup valve when necessary
Data Source
AI summary
A method of preventing drippage in a liquid dispensing system includes generating at least a first proxy signal representing at least a first indirect measure of a position of a first automatic control valve (ACV), wherein the first ACV has positions ranging from fully closed to fully open. The method further includes recognizing, based on at least the first proxy signal, whether a failure state exists in which the first ACV has failed to close. The method further includes causing a second ACV to close when the failure state exists, wherein the second ACV is fluidically connected to the first ACV, and the second ACV has positions ranging from fully closed to fully open.