Flow Rate Controller Using Stored Correction Factors for Multi-Gas Accuracy
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Solution Overview
Problem
Conventional flow rate controllers require complex manual calculations and are prone to errors when controlling the flow rates of multiple gaseous species due to varying specific heat values, leading to inaccuracies in processing gas flow rates during semiconductor wafer processing.
Innovation Solution
A flow rate controller with a conversion data storage unit that stores relationships between flow rate instruction signals and target flow rates for multiple gaseous species, allowing for automatic selection and calculation of target flow rates based on gaseous species selection signals, eliminating the need for manual correction factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If manual calculation and input of correction factors (CF values) is used to control flow rates of multiple gaseous species, then the flow rate controller can handle different gases, but the operation becomes complex and error-prone
Solution Approach 1:
The flow rate controller pre-stores correction factors (CF values) for multiple gaseous species in its memory before operation. When a gas type is selected, the corresponding CF value is automatically retrieved and applied, eliminating the need for operators to perform manual calculations and input corrections during operation.
Solution Approach 2:
The flow rate controller automatically selects and applies the appropriate correction factor based on the selected gaseous species without requiring external manual intervention. The system self-adjusts by internally retrieving the stored CF value corresponding to the selected gas and using it in the feedback control calculation.
2Adaptability or versatility
If manual calculation and input of correction factors is required, then the flow rate can be adjusted for different gases, but calculation errors may occur leading to inaccurate flow rates
Solution Approach 1:
The flow rate controller automatically retrieves and applies the correct correction factor from its pre-stored data, eliminating human calculation errors. The system self-corrects by internally matching the selected gas type with its corresponding CF value, ensuring accurate flow rate control without manual intervention.
Solution Approach 2:
The flow rate controller uses feedback control with pre-stored correction factors to automatically adjust and maintain accurate flow rates. The system continuously monitors the actual flow and compares it with the target flow (calculated using the appropriate CF value), making real-time corrections to eliminate errors.
3Measurement precision
If separate flow rate controllers are provided for each gaseous species, then accurate control for each gas is achieved, but installation cost increases
Solution Approach 1:
The flow rate controller is designed as a universal device capable of controlling multiple different gaseous species. It achieves this by pre-storing correction factors for various gases and automatically selecting the appropriate factor based on the selected gas type, allowing one controller to replace multiple specialized controllers.
Solution Approach 2:
The flow rate controller adjusts its control parameters dynamically based on the selected gaseous species. By changing the correction factor parameter internally according to the selected gas, the single controller adapts its behavior to accurately control different gas types without requiring multiple dedicated devices.
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
Enables accurate and simplified control of flow rates for multiple gaseous species without complex manual calculations, reducing the risk of errors and improving processing efficiency in semiconductor wafer processing.
Implementation Method 1
The flow rate controller obtains a flow rate (mass flow rate) by using amount of heat movement, which occurs due to flow of a gas inside a sensor pipe
Implementation Method 2
amount of heat movement, which occurs due to flow of a gas inside a sensor pipe, as a resistance variation of a resistance wire having a resistance value varying depending on a temperature
Data Source
AI summary
The flow rate controller controlling a flow rate of gas supplied through a gas passage includes: a main gas pipe; a flow rate detecting unit detecting the flow rate of gas supplied through the main gas pipe and outputting a flow rate signal; a flow rate control valve mechanism controlling a flow rate; a conversion data storage unit storing a plurality of pieces of conversion data corresponding to a plurality of gaseous species, to indicate a relationship between a flow rate instruction signal input from outside and a target flow rate; and a flow rate control main body which selects the corresponding conversion data from the conversion data based on a gaseous species selection signal input from outside, calculates the target flow rate based on the flow rate instruction signal, and controls the flow rate control valve mechanism based on the target flow rate and the flow rate signal.