MEMS Coriolis Flow Sensor for Low Gas Flow Precision
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Solution Overview
Problem
Current mass flow controllers (MFCs), such as thermal or pressure-based MFCs, face challenges in accurately controlling low gas flow rates and fast gas exchange times required for advanced substrate processing techniques like CVD, ALD, and ALE, particularly in semiconductor wafer processing.
Innovation Solution
A fluid delivery system incorporating microelectromechanical (MEMS) Coriolis flow sensors, which include a tube made of semiconductor material, vibrates at a resonant frequency to measure mass flow rates, and a controller determines the mass flow rate and density by analyzing the phase shift and oscillation frequency, allowing for precise control and verification of gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal or pressure-based MFCs are used, then the device complexity is reduced, but the measurement precision and control accuracy for low gas flow rates deteriorate
Solution Approach 1:
The patent replaces thermal or pressure-based measurement systems with a MEMS Coriolis flow sensor that uses mechanical vibration of a semiconductor tube. The tube is vibrated at its resonant frequency and the phase shift between drive and response signals is measured to determine mass flow rate, providing high precision measurement while maintaining relatively simple device structure
Solution Approach 2:
The patent employs mechanical vibration of a semiconductor tube at its resonant frequency as the core measurement mechanism. The Coriolis flow sensor vibrates the tube and detects phase shifts caused by mass flow, enabling precise measurement of low gas flow rates through mechanical means rather than thermal or pressure methods
2Speed
If conventional MFCs are used, then the response time is slower, but the gas exchange time for fast substrate processing deteriorates
Solution Approach 1:
The MEMS Coriolis flow sensor uses resonant vibration of a semiconductor tube to detect mass flow rate. This mechanical vibration-based measurement approach provides faster response time compared to thermal or pressure-based methods, enabling rapid gas exchange required for fast substrate processing techniques like ALD and ALE
Solution Approach 2:
The patent employs a dynamic measurement approach where the tube is continuously vibrated at resonant frequency and the phase shift is measured in real-time. This dynamic method allows for rapid detection of flow changes, improving response time for gas exchange operations
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 MEMS Coriolis flow sensors enable accurate measurement and control of low mass flow rates (less than 1000 sccm) with high precision, improving the efficiency and accuracy of gas delivery in substrate processing systems, particularly in etching and deposition processes.
Implementation Method 1
the MEMS Coriolis flow sensor vibrates the tube at a resonant frequency during measurement
Implementation Method 2
MEMS Coriolis flow sensor
Data Source
AI summary
A fluid delivery system includes N first valves. Inlets of the N first valves are fluidly connected to N gas sources, respectively, where N is an integer greater than zero. N mass flow controllers include a microelectromechanical (MEMS) Coriolis flow sensor having an inlet in fluid communication with an outlet of a corresponding one of the N first valves. A second valve has an inlet in fluid communication with an outlet of the MEMS Coriolis flow sensor and an outlet supplying fluid to treat a substrate arranged in a processing chamber. A controller in communication with the MEMS Coriolis flow sensor is configured to determine at least one of a mass flow rate and a density of fluid flowing through the MEMS Coriolis flow sensor.