Phosphoric Acid Etching Control via Liquid-Level Feedback
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Solution Overview
Problem
Existing substrate processing methods face challenges in maintaining consistent phosphoric acid concentration during etching processes due to fluctuations caused by evaporation and atmospheric pressure changes, which affect the boiling state of the phosphoric acid aqueous solution.
Innovation Solution
A substrate processing apparatus and method that includes a controller to regulate the supply flow rate of pure water based on liquid level detection, using feedback controls to stabilize the phosphoric acid concentration by adjusting the water supply rate in response to evaporation and atmospheric pressure variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the phosphoric acid aqueous solution is heated to maintain boiling state for etching, then the etching performance is improved, but the phosphoric acid concentration fluctuates due to evaporation
Solution Approach 1:
The system dynamically adjusts the pure water supply flow rate based on detected liquid level changes to compensate for concentration variations caused by evaporation during heating, maintaining stable phosphoric acid concentration despite temperature changes
Solution Approach 2:
The liquid level sensor continuously monitors the liquid level in the outer tub and provides feedback to the controller, which adjusts the pure water supply flow rate accordingly to maintain constant phosphoric acid concentration during the heating and etching process
2Reliability
If atmospheric pressure changes occur during processing, then the boiling state of the phosphoric acid aqueous solution changes, but the phosphoric acid concentration becomes unstable
Solution Approach 1:
The liquid level sensor provides continuous feedback on liquid level changes caused by atmospheric pressure variations, enabling the controller to adjust pure water supply in real-time to compensate for concentration instability
Solution Approach 2:
The system adjusts the pure water supply flow rate parameter dynamically in response to atmospheric pressure changes detected through liquid level variations, maintaining stable phosphoric acid concentration despite external pressure fluctuations
3Stability of the object's composition
If pure water is continuously supplied to maintain phosphoric acid concentration, then the concentration stability is improved, but the liquid level in the outer tub fluctuates
Solution Approach 1:
The liquid level sensor monitors the outer tub liquid level and provides feedback to the controller, which adjusts the pure water supply flow rate to maintain both concentration stability and acceptable liquid level in the outer tub
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses fluctuations in phosphoric acid concentration, ensuring consistent etching performance by maintaining the boiling state and concentration of the phosphoric acid aqueous solution, thereby improving processing efficiency and quality.
Implementation Method 1
a liquid level sensor configured to detect a liquid level of the phosphoric acid aqueous solution in the outer tub
Implementation Method 2
a pure water supply configured to supply pure water into the processing tub. The controller controls a supply flow rate of the pure water based on a detection value of the liquid level
Implementation Method 3
a circulation line configured to send the phosphoric acid aqueous solution taken out from the outer tub into the inner tub
Implementation Method 4
fluctuations caused by evaporation and atmospheric pressure changes, which affect the boiling state of the phosphoric acid aqueous solution
Data Source
AI summary
A substrate processing apparatus includes a substrate processing device for immersing a substrate in a phosphoric acid aqueous solution; and circuitry for controlling the substrate processing device. The substrate processing device includes: a processing tub including an inner tub in which the phosphoric acid aqueous solution is stored and an outer tub for collecting the phosphoric acid aqueous solution; a circulation line for sending the phosphoric acid aqueous solution taken out from the outer tub into the inner tub; a liquid level sensor for detecting a liquid level of the phosphoric acid aqueous solution in the outer tub; and a pure water supply for supplying pure water into the processing tub. The substrate is immersed in the phosphoric acid aqueous solution in the inner tub. The circuitry controls a supply flow rate of the pure water based on a detection value of the liquid level.