Cold Trap Rough Surface Ice Adhesion
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Solution Overview
Problem
Existing cryopumps face prolonged recovery times to achieve a desired vacuum degree due to the detachment of ice layers from the baffle surfaces, which leads to the rerelease of adsorbed process gas molecules, increasing the time required for vacuum chamber preparation for subsequent processes.
Innovation Solution
A cryopump design featuring a rough surface on the cold panel, achieved through matte plating or surface roughening treatments, enhances ice layer adhesion, reducing detachment and subsequent gas re-release, thereby shortening the recovery time to a desired vacuum level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a smooth surface is used on the cold panel, then the ice layer forms uniformly, but the ice layer detaches easily causing gas re-release and prolonged recovery time
Solution Approach 1:
The cold panel surface is modified to have a rough texture specifically at the interface where the ice layer forms. This local change in surface quality enhances mechanical interlocking between the ice layer and panel surface, preventing detachment while maintaining uniform ice formation across the panel.
Solution Approach 2:
The cold panel surface is pre-treated with a rough coating or texture before the ice layer forms. This preliminary modification of the surface structure ensures that when the ice layer subsequently forms and freezes to the panel, it achieves strong adhesion from the outset, preventing later detachment and gas re-release.
2Reliability
If the ice layer adheres strongly to the cold panel, then gas molecules are trapped effectively, but the surface treatment increases manufacturing complexity
Solution Approach 1:
The surface roughness of the cold panel is controlled within a specific range (e.g., Ra 0.4-1.6 μm) to achieve optimal ice layer adhesion. By precisely controlling the surface roughness parameter through standard coating techniques, the patent achieves effective gas trapping without excessive manufacturing complexity.
Solution Approach 2:
The patent employs cost-effective surface treatment methods such as matte plating or conventional roughening coatings that can be applied using standard manufacturing processes. These treatments provide sufficient ice layer adhesion for the intended application lifecycle without requiring complex or expensive specialized treatments.
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
The enhanced adhesion of the ice layer to the rough surface suppresses the re-release of process gas molecules, allowing for faster recovery of the vacuum chamber to a desired state, improving throughput in semiconductor manufacturing processes.
Implementation Method 1
a cold panel that is thermally connected with the refrigerator to be cooled
Implementation Method 2
a cryopump is a vacuum pump that captures and pumps gas molecules by condensing or adsorbing molecules on a cryopanel cooled to an extremely low temperature
Implementation Method 3
captures and pumps gas molecules by condensing or adsorbing molecules on a cryopanel
Implementation Method 4
a rough surface is formed on the cold panel... the adhesion with a condensed ice layer can be enhanced by having a rough surface on the cold panel
Data Source
AI summary
A cold trap includes a refrigerator and a cold panel that is thermally connected with the refrigerator to be cooled. A rough surface is formed on the cold panel. The cold trap is arranged, for example, in an evacuation channel for connecting a vacuum chamber with a turbo-molecular pump in order to freeze and capture, on a surface thereof, part of a gas that is to be sucked and pumped into the turbo-molecular pump from the vacuum chamber through the evacuation channel.