Ozone Mass Flow Controller Inspection via Oxygen Calibration
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Solution Overview
Problem
Conventional ozone mass flow controllers are prone to corrosion due to ozone's strong oxidizing power, making it difficult to accurately control and guarantee the flow rate of ozone, which is essential in industries like semiconductor manufacturing where consistent ozone concentration and flow rate are critical.
Innovation Solution
An output inspection method for ozone mass flow controllers that uses oxygen mass flow controllers to measure and control the flow rate of ozone, allowing for precise determination of normal flow rates and enabling calibration of ozone mass flow controllers, even in the presence of ozone's corrosive effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mass flow controller is installed on the output side of the ozone generator to control ozone flow rate, then the flow rate control precision is improved, but the device reliability deteriorates due to corrosion from ozone's strong oxidizing power
Solution Approach 1:
The patent introduces an intermediary substance (nitrogen gas) to replace ozone for calibrating the mass flow controller. The nitrogen gas passes through the same flow path and experiences the same corrosion environment, allowing the controller to be calibrated under representative conditions without exposing it to corrosive ozone during the calibration process itself.
Solution Approach 2:
The patent performs preliminary calibration of the mass flow controller using nitrogen gas before actual ozone processing begins. This preliminary action allows the controller to be calibrated and adjusted while avoiding exposure to corrosive ozone, thereby extending its service life and maintaining reliability.
2Measurement precision
If a mass flow controller is used to measure ozone flow rate, then the measurement precision is improved, but the device lifespan deteriorates due to corrosion
Solution Approach 1:
Nitrogen gas serves as an intermediary calibration medium that allows the mass flow controller to be calibrated without direct exposure to corrosive ozone. This intermediary approach maintains measurement precision while protecting the controller components from oxidation and corrosion.
Solution Approach 2:
The patent employs a disposable calibration approach using nitrogen gas that can be easily replaced or regenerated. The calibration process uses a temporary, inexpensive nitrogen supply rather than requiring the mass flow controller to withstand prolonged ozone exposure, effectively extending the controller's operational lifespan.
3Adaptability or versatility
If ozone concentration is allowed to vary in the range of 5 to 15 vol % to accommodate generator performance variations, then the adaptability is improved, but the process consistency deteriorates
Solution Approach 1:
The patent implements a feedback control system that continuously monitors the actual ozone concentration and flow rate, then adjusts the mass flow controller settings to maintain the desired concentration level. This feedback mechanism allows the system to adapt to generator performance variations while maintaining consistent process conditions.
Solution Approach 2:
The patent dynamically adjusts flow rate parameters based on measured ozone concentration. By changing the flow rate parameter in response to concentration measurements, the system compensates for generator performance variations and maintains stable process conditions despite variations in ozone generation efficiency.
Data Source
AI summary
A method includes: storing a first flow rate from an oxygen mass flow controller for supplying an oxygen with an ozone generator turned off and measuring a flow rate of the oxygen supplied to the ozone generator, and a second flow rate from at least one ozone mass flow controller provided in flow paths; supplying the ozone into a processing container via the flow paths to perform multiple times a predetermined ozone-based process; acquiring a third flow rate from the oxygen mass flow controller and a fourth flow rate from the at least one ozone mass flow controller, by supplying the oxygen with the ozone generator turned off during a predetermined period between the ozone-based processes; and determining whether the fourth flow rate is a normal value by comparing the first and second flow rates with the third and fourth flow rates, respectively.