Vacuum Valve Controller Lag Estimation

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Solution Overview

Problem

Existing vacuum valve control systems in semiconductor processes face inaccuracies in pressure adjustment due to the approximation of exhaust expressions that ignore pressure second-order derivative terms, limiting their effectiveness in estimating measurement lag and controlling chamber pressure.

Innovation Solution

A vacuum valve with a controller that estimates measurement lag information using an exhaust expression including a second-order derivative term, allowing for precise control of the valve element opening degree based on the estimated lag information and effective exhaust speed, thereby improving pressure adjustment accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the exhaust expression is approximated to ignore the pressure second-order derivative amount, then the calculation is simplified, but the estimation accuracy of measurement lag decreases

Engineering Contradiction:

Improvecalculation simplicityVSAvoidmeasurement lag estimation accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent changes the parameter of the exhaust expression by including the second-order derivative term of pressure measurement value, transforming the approximate expression into a more accurate model that accounts for dynamic pressure changes during step transitions

Inventive Principle:

Principle #35Parameter changes

2Speed

If the valve element opening degree is controlled based on approximate exhaust expression, then the control response is faster, but the pressure adjustment accuracy decreases

Engineering Contradiction:

Improvecontrol response speedVSAvoidpressure adjustment accuracy

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The patent implements feedback control by using the estimated measurement lag information (derived from the second-order derivative-based exhaust expression) to correct the valve element opening degree control, creating a closed-loop system that compensates for measurement delays and improves pressure adjustment accuracy

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11551952B2Vacuum valve, method of controlling vacuum valve, and estimation device

Publication Date: 2023.01.10 SHIMADZU CORP

AI summary

A controller includes an opening degree control section configured to control a valve element opening degree of the valve main body based on a pressure measurement value of the vacuum chamber measured by a vacuum meter, and an estimation section configured to estimate measurement lag information of pressure measurement value with respect to a pressure of the vacuum chamber based on (a) an exhaust expression including a second-order derivative term of the pressure measurement value and indicating a relationship between an effective exhaust speed of a vacuum pumping system for the vacuum chamber and the pressure measurement value and (b) a pressure measurement value measured during a pressure response when the valve element opening degree is step-changed, and the opening degree control section controls the valve element opening degree based on the measurement lag information estimated by the estimation section.