Dual ACV Drippage Prevention for Wafer Liquid Dispensing
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Solution Overview
Problem
In semiconductor wafer fabrication, drippage during deposition processes, such as washing, spin-coating of adhesion promoters, and spin-releasing of developers, can occur due to incomplete closure of automatic control valves, leading to reduced IC quality.
Innovation Solution
A drippage prevention system is implemented, featuring a main automatic control valve (ACV) retrofitted with a proxy sensor and a backup ACV fluidically connected between the main ACV and the nozzle, where the proxy sensor generates a signal for the controller to ensure the backup ACV closes if the main ACV fails to fully shut off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single automatic control valve is used to dispense liquid material, then the device complexity is low, but the reliability of liquid flow control deteriorates due to potential incomplete closure
Solution Approach 1:
The single valve system is segmented into a primary automatic control valve and a secondary automatic control valve. The primary valve handles normal operation, while the secondary valve acts as a backup to ensure complete flow shut-off when the primary valve fails to close properly, thereby improving reliability without requiring complete system redesign
Solution Approach 2:
The secondary valve is positioned downstream of the primary valve in the fluid flow path. This preliminary positioning ensures that if the primary valve fails to close completely, the secondary valve can still achieve complete flow shut-off, preventing drippage before it affects the wafer processing
2Manufacturing precision
If the valve closure position is not precisely monitored, then the ease of operation is high, but the manufacturing precision deteriorates due to drippage affecting IC quality
Solution Approach 1:
A sensor is implemented to detect the closure position of the primary automatic control valve and provide feedback signals to the controller. This feedback mechanism enables precise monitoring of valve closure status, allowing the system to detect incomplete closure and activate the secondary valve accordingly, thereby ensuring manufacturing precision without requiring complex manual intervention
Data Source
AI summary
A method of preventing drippage in a fluid dispensing system. The fluid dispensing system includes a first automatic control valve (ACV), an input of the first ACV connected to fluid-source of fluid, the first ACV having positions ranging from fully closed to fully open, and a second ACV, an input of the second ACV being connected to an output of the first ACV, and an output of the second ACV being connected to a nozzle, the second ACV having positions ranging from fully closed to fully open. The method includes generating a first proxy signal representing at least a first indirect measure of a position of the first ACV. The method includes recognizing, based on at least the first proxy signal that a failure state exists in which the first ACV has failed to close. The method includes causing the second ACV to close when the failure state exists.