Mass Flow Controller Verification Using Universal Mass Flow Meter
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Solution Overview
Problem
Semiconductor fabrication processes face challenges in maintaining accurate and repeatable gas flow rates due to inaccuracies in mass flow controllers (MFCs), leading to yield loss and increased costs, with existing verification methods being time-consuming and impractical for widespread implementation across multiple tools.
Innovation Solution
A system and method using a single mass flow meter (MFM) to verify and adjust gas flow rates for multiple MFCs across various tools, allowing for frequent calibration and detection of drift, thereby reducing process deviations and improving tool-to-tool matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass flow verifiers (MFVs) are used to monitor and verify MFC accuracy, then measurement precision is improved, but loss of time increases significantly
Solution Approach 1:
The patent uses a mass flow meter (MFM) as a reference copy to verify multiple MFCs simultaneously. Instead of using a slow MFV for each individual MFC verification, the system creates a reference measurement system that can quickly compare and verify multiple controllers in parallel, dramatically reducing verification time while maintaining precision through the reference standard approach
Solution Approach 2:
The verification process is segmented into reference calibration and comparative verification stages. The MFM is first calibrated as a reference standard, then multiple MFCs are verified by comparison against this segmented reference system, allowing parallel verification that reduces total time while maintaining measurement precision through the segmented reference approach
2Adaptability or versatility
If multiple mass flow meters are configured for different gas types and flow rate ranges, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal MFM that can measure multiple gas types and flow rate ranges by using calibration factors and scaling relationships. Instead of requiring separate specialized MFMs for each gas type and range, a single universal MFM performs all measurements by applying appropriate calibration data, dramatically reducing device complexity while maintaining full adaptability across different process conditions
3Reliability
If MFCs are frequently calibrated to detect drift early, then reliability is improved, but loss of time increases due to tool downtime
Solution Approach 1:
The patent replaces the traditional mechanical removal and physical calibration process with an automated in-situ verification system. The MFM verifies MFC accuracy while the MFC remains installed and operational, using automated data comparison and drift detection algorithms instead of manual mechanical calibration procedures, thereby eliminating tool downtime while maintaining reliability through frequent verification
Data Source
AI summary
A method and system are disclosed for verifying the flow rate of gas through a mass flow controller, such as a mass flow controller used with a tool for semiconductor or solar cell fabrication. To verify the mass flow rate measured by the mass flow controller, gas passing through the mass flow controller is also passed through a mass flow meter. The measured flow rate through the mass flow controller is compared to the measured flow rate through the mass flow meter and any difference between the two measured flow rates is determined. Depending upon the magnitude of any difference, the flow of gas to the mass flow controller may be altered.