Processing Liquid Valve Presetting for Stable Substrate Flow
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Solution Overview
Problem
Conventional substrate processing apparatuses experience fluctuations in flow volume when starting to supply processing liquid to a substrate due to changes in viscosity caused by disturbances such as residence time and environmental temperature during the transition from returning to supplying the liquid.
Innovation Solution
A substrate processing apparatus with a controller that calculates and sets the initial opening degree of a constant-pressure valve based on flowmeter measurements during a waiting time interval, ensuring a consistent flow volume when switching to a supplying time interval, thereby reducing fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the processing liquid is returned to the retaining tank via the returning line during waiting time, then the processing liquid can be prepared for the next supply, but fluctuation in flow volume occurs when switching to supply mode due to viscosity changes
Solution Approach 1:
The controller calculates the appropriate opening degree of the constant-pressure valve in advance during the waiting time interval, before the supply mode is activated. This preliminary calculation uses flowmeter measurements and current valve opening degree to predict the optimal setting, ensuring that when supply mode begins, the flow volume is already optimized and stable, avoiding fluctuations caused by viscosity changes during transition.
Solution Approach 2:
The system continuously monitors the actual flow volume using the flowmeter and uses this feedback information to adjust the constant-pressure valve opening degree. During waiting time, the feedback data is used to calculate the optimal opening degree for the upcoming supply phase, creating a closed-loop control that compensates for viscosity variations and maintains flow stability.
2Manufacturing precision
If the constant-pressure valve opening degree is adjusted dynamically based on flowmeter measurements, then flow volume stability is improved, but the control system becomes more complex
Solution Approach 1:
The controller performs the calculation of the optimal valve opening degree during the waiting time interval, before supply mode is needed. This timing strategy allows the system to prepare the precise control parameter in advance without impacting the actual supply process, achieving high precision flow control while minimizing the computational burden during critical supply phases.
Solution Approach 2:
The system uses its own operational data (flowmeter measurements and current valve opening degree) to automatically calculate and adjust the optimal valve settings. The controller serves itself by using real-time feedback from the flowmeter to determine the appropriate control actions, eliminating the need for external manual adjustment or complex external control systems.
Data Source
AI summary
A substrate processing apparatus includes a retaining tank, a circulation line, a supply line, a returning line, a flowmeter, a constant-pressure valve, and a controller. The circulation line returns, to the retaining tank, the processing liquid delivered from the retaining tank. The supply line connects the circulation line to a supply unit that supplies the processing liquid to a substrate. The returning line is connected to the supply line to return the processing liquid to the retaining tank. The flowmeter and the constant-pressure valve are provided on the supply line. The controller calculates, during a waiting time interval, an opening degree of the constant-pressure valve in supplying the processing liquid to the substrate based on a measurement value of the flowmeter and an opening degree of the constant-pressure valve, and during a supplying time interval, set an initial opening degree of the constant-pressure valve to the calculated one.