Pressure-Regulated Mass Flow Control for Corrosive Gas Delivery
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Solution Overview
Problem
Conventional mass flow controllers (MFCs) in electronic device manufacturing systems face limitations in accurately measuring and controlling gas flow rates across a wide range, leading to increased costs and potential gas decomposition or corrosion, especially when dealing with high flow rates or corrosive gases.
Innovation Solution
A pressure-regulated mass flow control apparatus comprising a flow restriction element, a pressure regulator, and a flow meter, where the system controller adjusts pressure settings based on measured flow rates to achieve target flow rates without altering the gas temperature, using calibration data to map pressure settings to flow rates, and optionally includes bypass flow elements for higher flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a thermal-based MFC is used to measure and control high flow rates (up to 500 slms), then the flow rate measurement capability is improved, but the gas temperature increase causes component corrosion or gas decomposition
Solution Approach 1:
The patent extracts the heating function from the flow measurement system. Instead of using thermal-based heating elements to measure flow rate, the system uses a pressure-based measurement approach where a known pressure drop across a flow restriction element directly indicates flow rate without temperature increase, thereby eliminating the harmful thermal effects while preserving measurement capability
Solution Approach 2:
The patent replaces the thermal-based measurement mechanism with a pressure-based mechanical measurement system. By measuring pressure differential across a restriction element rather than using thermal conduction or convection, the system achieves flow rate measurement without the harmful side effect of gas heating, thus preventing corrosion and decomposition
2Measurement precision
If a pressure-based MFC is used to achieve accurate measurement and control, then measurement accuracy is improved, but the downstream pressure must be maintained at approximately 400 torr or below which limits application flexibility
Solution Approach 1:
The patent inverts the traditional pressure-based MFC approach by placing the flow restriction element upstream rather than downstream. This allows the system to measure pressure differential in a region where pressure can be freely controlled without constraining downstream pressure, thereby maintaining measurement accuracy while increasing application flexibility
Solution Approach 2:
The patent introduces a flow restriction element as an intermediary component between the pressure regulator and the chamber. This intermediary creates a controlled pressure differential that can be measured accurately while allowing the downstream chamber pressure to be independently controlled, thus resolving the contradiction between measurement precision and application versatility
3Measurement precision
If a rate-of-decay MFC is used to control low flow rates (less than 2.0 slms), then low flow rate control is improved, but the application range is severely limited
Solution Approach 1:
The patent creates a universal flow control system that can handle a wide range of flow rates by combining a pressure regulator, flow restriction element, and pressure differential measurement. The system can be configured to control both very low flow rates (better than 2.0 slms) and high flow rates (up to 500 slms) using the same fundamental mechanism, thus achieving multi-functionality and broad application range
4Adaptability or versatility
If conventional MFCs are used to cover a wide range of flow rates, then flow rate coverage is improved, but the system cost increases significantly
Solution Approach 1:
The patent merges multiple functions into a single integrated system: the pressure regulator controls upstream pressure, the flow restriction element creates a predictable pressure differential, and the pressure sensor measures the differential to determine flow rate. This unified approach eliminates the need for multiple specialized MFCs, reducing system complexity and cost while maintaining wide flow rate coverage
Solution Approach 2:
The patent uses parameter changes in the pressure differential across the flow restriction element to achieve wide flow rate coverage. By measuring pressure differential rather than using multiple devices with different operating ranges, the system can accurately measure and control flow rates from very low to very high values using a single configuration, thereby reducing cost and complexity
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 solution enables precise control of gas flow rates from 0 to 500 slms without temperature adjustments, preventing component corrosion and decomposition, and allows for higher flow rates through bypass elements, enhancing the efficiency and cost-effectiveness of gas delivery systems.
Implementation Method 1
a flow restriction element configured to restrict a flow rate of a gas
Implementation Method 2
a pressure regulator coupled to an inlet of the flow restriction element, where the pressure regulator is configured to control a pressure of the gas
Implementation Method 3
a flow meter coupled to an outlet of the flow restriction element. The flow meter is configured to measure the flow rate of the gas
Data Source
AI summary
A manufacturing system includes a processing chamber, an gas supply, and a mass flow control apparatus coupled to the gas supply and the processing chamber. The mass flow control apparatus includes a flow restriction element configured to restrict a flow rate of a gas, a bypass flow element configured to control the flow rate of the gas in parallel to the flow restriction element, and a pressure regulator configured to control a pressure of the gas between the pressure regulator and the flow restriction element and/or a pressure of the gas between the pressure regulator and the flow restriction element. The manufacturing system further includes a controller that is configured to flow gas from the gas supply to the processing chamber via the mass flow control apparatus in view of a first pressure setting. The controller further determines to modify the flow of the gas from a first flow rate associated with the first pressure setting to a second flow rate. The controller further determines a second pressure setting associated with the second flow rate and causes the pressure regulator to modify the pressure of the gas between the pressure regulator and the flow restriction element and/or the pressure regulator and the bypass flow element in view of the second pressure setting.