MEMS Mass Flow Control for Fast Pulsed Gas Delivery
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Solution Overview
Problem
Conventional mass flow controllers (MFCs) in manufacturing systems have slow response rates, making them impractical for applications requiring precise gas control and timing, especially for high and low flow rate precision and pulsed gas delivery.
Innovation Solution
The use of micro-electromechanical systems (MEMS) devices directly in the gas flow path to provide fast and accurate flow feedback, coupled with a processing device to quickly control flow modulating valves, enabling transient response times less than 1 millisecond and precise control of gas flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal MFCs are used to measure and control gas flow, then mass flow control capability is provided, but the response rate is slow (100 milliseconds or longer)
Solution Approach 1:
The patent replaces thermal-based sensing mechanisms with micro-electromechanical systems (MEMS) that utilize mechanical motion of a diaphragm in response to pressure differential. This mechanical-based MEMS device provides faster response time compared to thermal sensing, achieving response rates significantly quicker than 100 milliseconds while maintaining accurate mass flow control capability.
2Manufacturing precision
If conventional MFCs are used, then basic flow control is achieved, but precise control of high and low flow rates cannot be simultaneously achieved
Solution Approach 1:
The patent employs a dynamic control system where the MEMS device continuously monitors pressure differential and provides real-time feedback to a control valve. This dynamic feedback mechanism enables precise control across a wide range of flow rates from low (10 sccm or less) to high (500 sccm or more), adapting to varying flow conditions that conventional static MFCs cannot handle simultaneously with precision.
3Measurement precision
If thermal sensors are used for flow feedback, then flow measurement is provided, but the feedback is slow resulting in slow MFC response
Solution Approach 1:
The patent substitutes thermal sensing with a mechanically-based MEMS pressure differential sensor that directly measures flow-induced pressure changes. This mechanical measurement approach eliminates the thermal response delay, providing immediate feedback when gas flow changes occur, thereby reducing feedback time significantly compared to thermal sensor-based systems.
4Ease of operation
If standard MFCs are used, then continuous flow control is achieved, but pulsed gas delivery with precise timing cannot be provided
Solution Approach 1:
The patent implements a closed-loop feedback system where the MEMS device continuously monitors pressure differential and provides real-time feedback to the control valve. This rapid feedback mechanism enables precise timing control for pulsed gas delivery by immediately responding to control signals and adjusting flow accordingly, achieving pulse widths and timing precision that cannot be accomplished with conventional open-loop or slow-response MFCs.
Data Source
AI summary
Disclosed herein are embodiments of a mass flow control apparatus, systems incorporating the same, and methods using the same. In one embodiment, a mass flow control apparatus comprises a flow modulating valve configured to modulate gas flow in a gas flow channel, a sensor device, such as a micro-electromechanical (MEMS) device, configured to generate a signal responsive to a condition of the gas flow, and a processing device operatively coupled to the flow modulating valve and the sensor device to control the flow modulating valve based on a signal received from the sensor device.