Multi-Point Liquid Level Control for Semiconductor Chemical Tanks
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Solution Overview
Problem
Existing liquid storage systems in semiconductor manufacturing lack efficient and precise control over liquid levels and replenishment, leading to inconsistent supply and potential system interruptions due to insufficient or excessive liquid levels.
Innovation Solution
A liquid storage apparatus equipped with a liquid level sensor having multiple detectors along the height direction, allowing for the setting of at least three liquid level determination positions, and a control unit that manages liquid replenishment based on these positions, adjusting for thermal expansion and precipitate accumulation to maintain stable liquid levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a liquid level sensor with only two detection points (highest and lowest liquid levels) is used, then the device complexity is reduced, but the manufacturing precision and control accuracy of liquid replenishment deteriorates
Solution Approach 1:
The liquid level sensor is segmented into multiple detectors (four or more) arranged along the height direction of the container body, with at least three liquid level determination positions assigned to different detectors. This segmentation enables precise control of liquid replenishment at multiple specific levels, resolving the contradiction between simple sensor structure and accurate liquid level control.
2Reliability
If liquid replenishment is performed frequently to maintain adequate liquid levels, then the reliability of substrate processing is improved, but the productivity decreases due to repeated interruptions
Solution Approach 1:
The system performs preliminary action by detecting liquid levels at multiple determination positions in advance and calculating the required replenishment amount before substrate processing is interrupted. The control unit determines the precise volume needed to reach the target liquid level, enabling replenishment to be completed quickly and efficiently, thus maintaining reliability while minimizing productivity loss.
3Device complexity
If the liquid level determination position is fixed at a single detector, then the device complexity is reduced, but the adaptability to varying conditions (temperature changes, precipitate accumulation) deteriorates
Solution Approach 1:
The liquid level determination position is made dynamic rather than fixed. The control unit can selectively determine different liquid level determination positions based on operating conditions such as temperature changes and precipitate accumulation. This dynamic adjustment capability allows the system to adapt to varying conditions while maintaining a relatively simple sensor structure with multiple detectors available for selection.
Data Source
AI summary
A liquid storage apparatus includes: a container body storing a processing liquid for a substrate processing apparatus therein; a liquid level sensor provided in the container body, and detecting a liquid level of the processing liquid stored in the container body; a replenishment unit replenishing the processing liquid in the container body; and a control unit acquiring detection information from the liquid level sensor, and performing a processing. The liquid level sensor includes four or more detectors capable of detecting the liquid level of the processing liquid along a height direction of the container body, and the control unit sets at least three liquid level determination positions corresponding to different detectors, respectively, among the four or more detectors, and controls a replenishment of the processing liquid from the replenishment unit to the container body based on detection information of the set at least three liquid level determination positions.