Gas Estimation Device for Vacuum Pumping Pressure Control
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Solution Overview
Problem
In vacuum devices like etching devices, pressure control accuracy is compromised when the type of gas being exhausted is unknown, as existing systems rely on pre-stored exhaust characteristic data based on standard gases like nitrogen or argon, which does not account for variations in gas types.
Innovation Solution
A gas estimation device that estimates the flow rate and type of gas being vacuum-pumped using correlation data and motor current values, allowing for real-time correction of automatic pressure control valve operations based on estimated gas type and flow rate, thereby improving pressure control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pre-stored exhaust characteristic data based on standard gases is used for pressure control, then the system is simple to operate, but pressure control accuracy deteriorates when the actual gas type differs from the standard gas
Solution Approach 1:
The system introduces feedback by measuring the motor current value of the vacuum pump and using it to estimate the actual gas type and flow rate. This feedback loop allows the pressure control valve to adjust its operation based on real-time gas conditions rather than relying solely on pre-stored data for standard gases, thereby resolving the contradiction between ease of operation and pressure control accuracy.
Solution Approach 2:
The system changes the parameter used for pressure control from fixed pre-stored exhaust characteristic data to dynamic estimation based on motor current value. By using motor current as a variable parameter that reflects actual gas conditions, the system adapts to different gas types and flow rates, improving pressure control accuracy while maintaining ease of operation.
2Measurement precision
If exhaust characteristic data for multiple gas types is stored in advance, then pressure control accuracy improves, but device complexity increases
Solution Approach 1:
The system replaces the mechanical approach of storing multiple sets of exhaust characteristic data for different gas types with an estimation mechanism based on motor current value. Instead of having separate data tables for each gas type, the system uses the motor current as a proxy to estimate gas properties and adjust pressure control accordingly, reducing device complexity while maintaining accuracy.
Solution Approach 2:
The motor current value serves multiple functions: it indicates the vacuum pump's operating state, helps estimate the gas type, and enables flow rate calculation. This multi-functionality eliminates the need for separate measurement devices or multiple data storage systems for different gas types, reducing device complexity while improving pressure control accuracy.
3Measurement precision
If motor current value is used to estimate gas type and flow rate, then pressure control accuracy improves, but use of energy increases due to additional measurements and calculations
Solution Approach 1:
The system uses the motor current value, which is already being measured for vacuum pump operation control, to simultaneously estimate gas type and flow rate. By reusing this existing measurement data for additional purposes, the system avoids the need for separate measurement devices and additional energy-consuming sensors, thereby improving pressure control accuracy without significantly increasing energy consumption.
Data Source
AI summary
A gas estimation device for estimating a flow rate and a gas type of gas to be vacuum-pumped by a vacuum pumping device including a vacuum pump and an automatic pressure control valve connected to a suction port of the vacuum pump, comprises: a correlation data storage section configured to store first correlation data containing correlation data regarding an opening degree control gain value of the automatic pressure control valve and correlation data regarding an effective exhaust velocity of the vacuum pumping device and second correlation data indicating a correlation among a flow rate, a gas type, and a motor current value in the vacuum pump; and a first estimation section configured to estimate the flow rate and the gas type of the gas to be vacuum-pumped by the vacuum pumping device based on at least the first correlation data and the second correlation data.