Vacuum Pressure Valve Conductance Mapping for Predictive Diagnostics
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Solution Overview
Problem
Vacuum pressure control systems, particularly in semiconductor processing, face performance degradation due to deposition by-products buildup and flapper seal wear, leading to inconsistent valve conductance and system faults, which existing methods fail to accurately diagnose and correct.
Innovation Solution
A method for calibrating vacuum valves by measuring and comparing conductance versus angular position to determine a conductance map, generating diagnostic indications for faults such as flapper seal wear, deposition by-products, and conduit blockages, ensuring repeatable performance and chamber matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If valve conductance is controlled by varying flapper position, then flow control is achieved, but deposition by-products accumulate and flapper seal wear occurs over time, degrading system performance
Solution Approach 1:
The system performs preliminary calibration to establish a reference conductance map for the valve before normal operation. This reference profile is stored and used to detect deviations caused by deposition or wear, enabling early diagnostic action before performance degradation becomes critical.
Solution Approach 2:
The system continuously monitors actual valve conductance by measuring pressure differential across the valve and comparing it against the stored reference conductance map. When deviations exceed thresholds, the system generates diagnostic indications and can trigger maintenance alerts, creating a closed-loop feedback mechanism for predictive maintenance.
2Measurement precision
If periodic recalibration of valve iso-curve is performed, then flow accuracy is improved, but system downtime and operational complexity increase
Solution Approach 1:
A reference conductance map is established during an initial calibration phase, capturing the valve's ideal conductance characteristics across its full range of motion. This preliminary measurement enables continuous monitoring without requiring repeated recalibration, reducing maintenance downtime.
Solution Approach 2:
The system performs self-diagnosis by automatically comparing real-time conductance measurements against the stored reference profile. This self-monitoring capability eliminates the need for frequent manual recalibration by operators, reducing both downtime and operational complexity.
3Measurement precision
If conductance measurements are continuously monitored, then fault detection accuracy is improved, but measurement and diagnostic complexity increases
Solution Approach 1:
The diagnostic range is segmented into distinct zones based on valve position and conductance deviation patterns. Different fault types (seal wear, deposition, blockage) produce characteristic patterns in specific segments of the conductance map, enabling simplified fault classification without complex algorithms.
Solution Approach 2:
The system transforms raw conductance measurements into diagnostic parameters by comparing actual conductance against the reference map at corresponding valve positions. This parameter transformation converts complex continuous data into discrete diagnostic categories, simplifying fault identification.
Data Source
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Figure 3A~3B
AI summary
Calibration of a valve in a vacuum system and providing a diagnostic indication in the vacuum system using the calibration includes measuring conductance of the valve as a function of angular valve position and generating a conductance calibration map or function for use during operation of the valve. An actual angular valve position is set based on the received set point angular valve position and a difference between the measured valve conductance and a predefined metric of conductance versus angular valve position. An actual system conductance and a difference between the actual system conductance and a reference system conductance for the system are determined. The diagnostic indication of a fault in the system is generated based on the actual angular valve position of the valve and the difference between the actual system conductance and the reference system conductance for the system.