Flow Ratio Controller Using Valve Models for Precise Gas Splitting
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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 outlet pressure sensors, leading to inconsistencies in gas distribution.
Innovation Solution
The implementation of piezoelectric valves and shared inlet pressure sensors, combined with valve flow models, allows for precise control of gas distribution without the need for flow meters, using inlet and outlet pressure sensors to determine flow rates through each channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass flow meters and outlet pressure sensors are used in conventional flow ratio controllers, then flow measurement capability is provided, but measurement precision and stability deteriorate due to sensor differences and inaccuracies
Solution Approach 1:
The patent removes mass flow meters and outlet pressure sensors from the system, extracting the problematic measurement components that caused inaccuracies. Instead, it uses only inlet pressure sensors combined with valve position sensors and flow models to calculate outlet flows, eliminating the source of measurement errors and inconsistencies.
Solution Approach 2:
The patent replaces physical flow measurement devices (mass flow meters) with a computational approach using flow models that calculate flow based on pressure differential and valve position. This substitution of mechanical measurement systems with mathematical modeling eliminates hardware-related measurement errors.
2Reliability
If conventional flow ratio controllers use multiple sensors and flow meters, then flow distribution is monitored, but device complexity increases leading to slower response times
Solution Approach 1:
The patent extracts and removes multiple sensors (outlet pressure sensors) and flow meters from the conventional system, simplifying the device architecture. The remaining system uses fewer components (inlet pressure sensors and valve position sensors) to achieve the same control function with reduced complexity and faster response.
Solution Approach 2:
The system uses the existing valve position sensors and inlet pressure sensors to self-determine outlet flow rates through computational models, eliminating the need for separate measurement devices. This self-service approach reduces component count while maintaining control accuracy.
3Measurement precision
If outlet pressure sensors are installed at each channel, then outlet pressure measurement is achieved, but device complexity and cost increase
Solution Approach 1:
The patent removes outlet pressure sensors from each channel, extracting the problematic measurement component. Instead of measuring outlet pressure directly, the system calculates outlet flow and inferred outlet pressure conditions using inlet pressure measurements combined with valve position and flow models, achieving the same control objective with fewer sensors.
4Ease of operation
If multiple flow meters and sensors are used in each channel, then individual flow control is enabled, but response time to changing flow rates deteriorates
Solution Approach 1:
The patent removes flow meters from individual channels, extracting the measurement devices that introduced response delays. The system achieves individual channel flow control through computational models that rapidly calculate required flow adjustments based on inlet pressure and valve position, enabling faster response to changing flow rate requirements.
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 time in gas distribution systems, ensuring consistent and repeatable delivery of precise gas ratios to multiple channels.
Implementation Method 1
Disclosed example flow ratio controllers use piezoelectric valves and an inlet pressure sensor that is shared between all of the outlet channels of the flow ratio controller
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
Disclosed example flow ratio controllers include: an inlet configured to receive a input process gas flow; an inlet pressure sensor configured to measure an inlet pressure; first and second outlets configured to output first and second portions of the input process gas flow; first and second flow valves configured to control a flow of the input process gas to the first and second outlets; first and second position sensors configured to measure valve positions of the first and second flow valves; first and second outlet pressure sensors configured to measure outlet pressures of the first and second outlets; and control circuitry configured to control the first flow valve and the second flow valve using a valve flow model and based on a predetermined flow ratio for the first outlet and the second outlet, the inlet pressure, the first and second valve positions, and the first and second outlet pressures.