Movable Cryopump Layout for Fast Pumping and Isolated Regeneration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cryopumps experience significant loss of pumping speed due to their geometry, which limits their efficiency in maintaining vacuum conditions for semiconductor device fabrication, as the regeneration process releases captured molecules back into the processing chamber, reducing the effective pump speed.
Innovation Solution
A movable cryopump arrangement that transitions between an operational position, where the front surface is aligned with the processing chamber to enhance pumping speed, and a regeneration position, where it is retracted into a cavity isolated from the chamber, ensuring efficient molecule capture and removal without releasing them back into the processing chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cryopump is positioned with its front surface setback from the processing chamber wall, then the regeneration process can be isolated from the processing chamber, but the pumping speed is reduced due to geometric limitations
Solution Approach 1:
The cryopump is made movable rather than fixed, allowing it to transition between two positions: a first position during regeneration where the front surface is setback and isolated from the processing chamber, and a second position during operation where the front surface extends into the processing chamber to maximize pumping speed. This dynamic repositioning resolves the contradiction by providing both isolation and high pumping speed at different operational phases
Solution Approach 2:
The operational cycle is segmented into distinct phases: regeneration phase where the cryopump is positioned for isolation, and operation phase where it is positioned for maximum pumping speed. The movable gate and movable cryopump work together to separate these functions in time and space, allowing the system to achieve both reliability during regeneration and high productivity during operation
2Productivity
If additional pumps are added to compensate for the reduction in pump speed, then the desired pump speed can be achieved, but the system complexity and cost increase
Solution Approach 1:
By making the cryopump movable and allowing it to extend into the processing chamber during operation, the system achieves high pumping speed without requiring additional pumps. The dynamic positioning optimizes the conductance and pumping efficiency, eliminating the need for extra pumping equipment and reducing system complexity
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 configuration improves the effective pump speed by 20-60% and prevents the release of previously captured molecules back into the processing chamber during regeneration, maintaining efficient vacuum conditions.
Implementation Method 1
Molecules that contact the cryogenic surfaces within the cryopump lose their thermal energy, condense and change from a gaseous state to a solid state (i.e. frost or ice). This cryocondensation traps or captures the gas on the low temperature surfaces
Implementation Method 2
Regeneration may be performed by raising the temperature of the cryopump, so that the condensate evaporates. Once evaporated, these molecules are exhausted from the chamber
Implementation Method 3
A movable gate is disposed in front of the cavity that contains the cryopump. When the cryopump is regenerated, the gate is closed, isolating the cavity from the processing chamber and allowing the evaporated molecules to be exhausted without affecting the processing chamber
Data Source
AI summary
An apparatus including a movable cryopump that may be disposed in a first operational position and a second regeneration position is disclosed. In the first operational position, the front surface of the cryopump may be disposed in the same plane as the wall of the processing chamber, effectively serving as a part of a chamber wall. In certain embodiments, the front surface of the cryopump may extend into the processing chamber. In the second regeneration position, the cryopump is retracted into a cavity, which is isolated from the processing chamber by a movable gate. The first operational position serves to enhance the pumping speed of the cryopump, while the second regeneration position ensures that previously trapped molecules are not released back into the processing chamber.