Flow Ratio Controller Using Pressure Models Instead of Flow Meters
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Solution Overview
Problem
Conventional flow ratio controllers in semiconductor manufacturing suffer from inaccuracies and slow response times due to the use of mass flow meters and pressure sensors that can introduce errors in flow ratio distribution.
Innovation Solution
The use of piezoelectric valves and shared inlet pressure sensors, combined with valve flow models and pressure sensors, allows for precise control of gas distribution without the need for flow sensors, enabling accurate and repeatable gas delivery to multiple channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass flow meters and pressure sensors are used in conventional flow ratio controllers, then flow measurement and control capability is provided, but measurement accuracy and response time deteriorate due to errors in flow ratio distribution
Solution Approach 1:
The patent removes mass flow meters from the system entirely, extracting the problematic measurement component that introduced errors. Instead of using mass flow meters to measure and control flow ratios, the invention relies solely on pressure sensors and valve position sensors combined with flow models, eliminating the source of measurement errors and improving flow ratio distribution accuracy.
2Productivity
If conventional pressure sensors and mass flow meters are used, then flow control function is achieved, but response time becomes slow
Solution Approach 1:
The patent replaces the mechanical measurement system (mass flow meters) with a computational approach using pressure sensors, valve position sensors, and flow models. This substitution eliminates the mechanical measurement bottleneck and enables faster digital processing of flow control calculations, significantly improving response time and reducing control adjustment time.
3Quantity of substance
If multiple sensors including mass flow meters are used, then comprehensive flow measurement is achieved, but device complexity increases
Solution Approach 1:
The patent merges the functions of mass flow meters and pressure sensors into a unified measurement approach using only pressure sensors combined with valve position sensors and flow models. This consolidation reduces the number of separate measurement devices needed, simplifying the sensor system while maintaining comprehensive gas flow measurement capability through computational methods.
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
This approach enhances stability, accuracy, and response times in gas distribution systems by using inlet and outlet pressure sensors, along with valve position sensors, to maintain predetermined flow ratios and pressure ranges, improving consistency and cost-effectiveness.
Implementation Method 1
The use of piezoelectric valves and shared inlet pressure sensors, combined with valve flow models and pressure sensors, allows for precise control of gas distribution
Data Source
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AI summary
Disclosed example flow ratio controllers include: an inlet; an inlet pressure sensor; first and second outlets; first and second flow valves; first and second position sensors; first and second outlet pressure sensors; and control circuitry configured to: control the first flow valve and the second flow valve based on a predetermined flow ratio for the first outlet and the second outlet, an inlet pressure, the first valve position, the second valve position, the first outlet pressure, and the second outlet pressure; determine a rate of change of the inlet pressure based on measurements from the inlet pressure sensor; and based on the inlet pressure and the rate of change of the inlet pressure, control the first flow valve and the second flow valve to maintain the inlet pressure within a predetermined range of a predetermined inlet pressure.