Cryopump Exhaust Line Buffer Volume for Hazardous Gas Dilution
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Solution Overview
Problem
In cryopump systems used for semiconductor manufacturing, hazardous gases stored in cryopumps can rapidly re-vaporize during regeneration, leading to increased concentrations that pose safety risks, requiring excessive purge gas to maintain safe levels.
Innovation Solution
The implementation of a cryopump system with a buffer volume in the exhaust line and a regeneration controller that manages purge gas flow rates between body purge, upstream purge, and downstream purge to efficiently dilute hazardous gases, including the use of additional purge gas from other cryopumps to reduce concentration peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If purge gas is supplied to dilute hazardous gases during regeneration, then safety is improved, but purge gas consumption increases
Solution Approach 1:
The patent merges the exhaust lines of multiple cryopumps into a common exhaust line with a buffer volume. During regeneration, cryopumps that are not currently regenerating provide purge gas through their exhaust lines to the common exhaust line, where it mixes with the exhaust from regenerating cryopumps. This combining approach allows efficient dilution of hazardous gases while reducing overall purge gas consumption compared to traditional methods where each cryopump would require separate purge gas supply.
Solution Approach 2:
The common exhaust line with buffer volume acts as an intermediary between the cryopumps and the external environment. It receives exhaust gas from regenerating cryopumps and mixes it with purge gas from non-regenerating cryopumps, thereby diluting the hazardous gas concentration before discharge. This intermediary structure enables safe gas disposal while optimizing purge gas usage.
2Productivity
If multiple cryopumps are connected to a common exhaust line, then system efficiency is improved, but control complexity increases
Solution Approach 1:
The patent segments the exhaust system into individual cryopump exhaust lines that connect to a common exhaust line with buffer volume. Each cryopump maintains its own exhaust path, but these paths converge at the common exhaust line. This segmentation allows independent control of each cryopump's regeneration cycle while benefiting from the shared exhaust infrastructure, improving overall system efficiency without requiring complex centralized control.
Solution Approach 2:
The common exhaust line serves multiple functions: it collects exhaust gas from multiple cryopumps, provides a mixing chamber for dilution, and acts as a shared purge gas distribution path. This multi-functionality reduces the need for separate exhaust and purge gas systems, simplifying the overall configuration while improving productivity.
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 approach effectively suppresses hazardous gas concentration peaks in the exhaust fluid, enhancing safety by efficiently diluting gases and reducing purge gas consumption compared to traditional methods.
Implementation Method 1
A cryopump is a vacuum pump that captures gas molecules through condensation and adsorption on a cryopanel cooled to a cryogenic temperature
Implementation Method 2
A cryopump is a vacuum pump that captures gas molecules through condensation and adsorption on a cryopanel cooled to a cryogenic temperature
Implementation Method 3
supplying a purge gas to the exhaust valve or downstream thereof... effectively suppresses hazardous gas concentration peaks in the exhaust fluid, enhancing safety by efficiently diluting gases
Data Source
AI summary
A cryopump system includes a plurality of cryopumps each of which includes a cryopump container, an exhaust valve that exhausts an exhaust fluid from the cryopump container, and an exhaust purge valve that supplies a purge gas to the exhaust valve or downstream thereof and an exhaust line through which the exhaust fluid is exhausted from the plurality of cryopumps to a treatment device, the exhaust line including a plurality of branch lines and a merging line, the plurality of branch lines each connected to the exhaust valve and the exhaust purge valve of a corresponding cryopump, the merging line connecting the plurality of branch lines to the treatment device.