Flow Ratio Control Using Pressure Models for Stable Gas Distribution
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Solution Overview
Problem
Conventional flow ratio controllers in semiconductor manufacturing suffer from inaccuracies and slow response times due to differences in sensor readings and the reliance on mass flow meters, leading to inconsistent gas distribution.
Innovation Solution
The use of piezoelectric valves and shared inlet pressure sensors, combined with valve flow models and pressure sensors, allows for precise gas distribution without flow sensors, using inlet and outlet pressures to control flow ratios through each channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass flow meters and multiple sensors are used in conventional flow ratio controllers, then flow measurement capability is provided, but measurement accuracy deteriorates due to sensor reading differences and system complexity increases
Solution Approach 1:
The patent removes mass flow meters from the system and extracts the flow measurement function entirely, relying instead on pressure sensors and flow models. This eliminates the source of sensor reading differences while reducing device complexity.
Solution Approach 2:
A single shared inlet pressure sensor serves multiple channels simultaneously, providing universal measurement capability without requiring individual sensors for each channel. This reduces component quantity while maintaining measurement functionality across all channels.
2Reliability
If conventional flow ratio controllers use multiple sensors per channel, then flow detection is enabled, but response time deteriorates due to processing multiple sensor readings and mass accumulation effects
Solution Approach 1:
The patent removes mass flow meters that cause mass accumulation delays and replaces them with pressure-based flow models that provide immediate flow determination from pressure readings without mass accumulation effects.
Solution Approach 2:
The system implements continuous pressure monitoring with feedback control that immediately adjusts flow valve positions based on real-time pressure differences, enabling rapid response without the delays associated with mass accumulation in conventional systems.
3Quantity of substance
If flow ratio controllers rely on mass flow meters, then flow measurement is provided, but stability deteriorates due to sensor differences and mass accumulation effects
Solution Approach 1:
The patent removes mass flow meters that introduce mass accumulation effects and sensor variability, replacing them with a stable pressure-based measurement system that provides consistent flow determination without mass accumulation instability.
Solution Approach 2:
The system transitions from measuring mass flow directly to measuring pressure parameters and calculating flow from pressure differences. This parameter change eliminates mass accumulation effects and sensor reading differences, providing stable and repeatable flow distribution.
4Measurement precision
If conventional systems use individual pressure sensors for each channel, then channel-specific pressure measurement is enabled, but device complexity increases
Solution Approach 1:
The patent implements a single shared inlet pressure sensor that serves all channels simultaneously. Combined with outlet pressure sensors and flow models, this universal inlet measurement provides accurate flow determination for all channels without requiring individual inlet sensors for each channel.
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 gas delivery to multiple channels.
Implementation Method 1
The use of piezoelectric valves and shared inlet pressure sensors
Data Source
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.