Chamber Partial Pressure Control Using Observer-Based Flow Estimation
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Solution Overview
Problem
Conventional concentration control systems in semiconductor manufacturing face challenges in accurately and rapidly controlling partial pressures within a chamber due to measurement delays and noise, especially when using NDIR analyzers, which result in unsatisfactory response speed and accuracy.
Innovation Solution
A concentration control system that includes a flow rate control device, a partial pressure measurement device, an observer model, and a controller, where the inflow flow rate and measurement partial pressures are input into the observer to estimate the chamber's partial pressure, allowing for real-time correction and improved responsiveness by setting the flow rate based on estimated values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If NDIR analyzer is used to measure partial pressure inside the chamber, then measurement accuracy is improved, but response time increases and noise increases
Solution Approach 1:
The system performs preliminary action by measuring the flow rate of gas supplied to the chamber beforehand, and using this information in conjunction with the NDIR measurement to calculate and predict the actual partial pressure inside the chamber, compensating for the inherent delay in NDIR response
Solution Approach 2:
The patent introduces an intermediary calculation process that combines NDIR measurement data with flow rate information to derive the actual partial pressure, acting as a mediator between the delayed NDIR measurement and the required real-time control
2Measurement precision
If NDIR analyzer is used to measure partial pressure inside the chamber, then measurement accuracy is improved, but noise level increases
Solution Approach 1:
The system implements feedback by continuously monitoring the flow rate and using it to correct and refine the partial pressure calculation based on NDIR measurements, reducing the impact of noise through continuous validation and adjustment
Solution Approach 2:
The flow rate measurement serves as an intermediary that helps filter and validate the NDIR signal, providing an additional reference point that reduces the influence of noise on the final partial pressure determination
3Speed
If partial pressure is measured in the supply flow path, then response speed is improved, but measurement accuracy deteriorates due to adsorption
Solution Approach 1:
The system uses flow rate information as an intermediary to bridge the gap between the upstream measurement location and the actual chamber conditions, allowing accurate calculation of chamber partial pressure without requiring the measurement device to be physically present in the chamber
Solution Approach 2:
The system performs preliminary measurement of the gas composition in the supply flow path before the gas enters the chamber, and uses this information combined with flow rate data to predict the chamber conditions in advance
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 system reduces noise and time delay, enabling immediate reflection of actual concentration changes and enhancing the accuracy and responsiveness of partial pressure control compared to conventional methods.
Implementation Method 1
the concentration of the material gas in the gas mixture, in other words, the partial pressure of the material gas is measured by an absorption spectrometer such as an NDIR (Non-Dispersive Infrared) analyzer
Data Source
AI summary
Provided is a concentration control system that has only a small time delay, obtains accurate estimated values, and also enables partial pressure control having improved responsiveness and accuracy. The system includes a flow rate control device provided on a supply flow path that supplies gas to a chamber, and controls a flow rate of a gas in the supply flow path to match a set flow rate, a partial pressure measurement device for a gas inside the chamber, an observer having a model which estimates a state of the gas inside the chamber, where a flow rate of the gas flowing into the chamber and measured partial pressures are input into the model, and an estimated partial pressure of the gas within the chamber is output, and a controller that, based on a set partial pressure and on the estimated partial pressure, sets the set flow rate.