Gas Expansion Module for Rapid Vacuum Pump-Down
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Solution Overview
Problem
Semiconductor processing tools face challenges in rapidly achieving and maintaining vacuum conditions within loadlocks, especially when transitioning between high-pressure ambient conditions and low-pressure vacuum environments, leading to prolonged pump-down times and inefficiencies.
Innovation Solution
The integration of a gas expansion volume, which is at least one and a half times larger than the loadlock volume, connected via a valve that can be opened to equalize pressures, allowing for rapid pressure drops by combining gas from the loadlock and expansion volumes, and utilizing a combination of roughing and high-vacuum pumps to manage pressure within the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a loadlock volume is directly pumped down from atmospheric pressure, then the pump-down time is extended, but the system structure remains simple
Solution Approach 1:
The loadlock system is segmented into two distinct volumes: the original loadlock volume and an additional gas expansion volume. This segmentation allows the pumping process to occur in stages - first pumping the expansion volume to high vacuum, then using it as a buffer to rapidly equalize pressure with the loadlock volume, thereby dramatically reducing total pump-down time without requiring a larger or more complex primary vacuum system
Solution Approach 2:
The gas expansion volume serves as an intermediary buffer between the atmospheric environment and the high-vacuum loadlock volume. By introducing this intermediate chamber that can be independently pumped to high vacuum, the system creates a pressure gradient pathway that accelerates the overall pressure equalization process while maintaining structural simplicity
2Loss of time
If the loadlock volume is increased to accommodate gas expansion, then the pump-down time is reduced, but the apparatus size increases
Solution Approach 1:
The gas expansion volume is nested within or adjacent to the existing loadlock structure, sharing common walls and support infrastructure. This nested configuration allows the expansion volume to be integrated into the existing apparatus footprint rather than requiring a completely separate, larger structure, thus reducing pump-down time while minimizing increase in overall apparatus size
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 solution significantly reduces the time required to achieve desired vacuum conditions in the loadlock, potentially decreasing pump-down time by orders of magnitude, thereby improving processing efficiency and handling of wafers with materials that outgas, such as epoxy.
Implementation Method 1
a gas expansion volume that is configured to be or is operably configurable to be at least one and a half times larger than the loadlock volume
Implementation Method 2
The first mechanism may include a turbopump configured to evacuate gas from the gas expansion volume
Implementation Method 3
In some alternative or further implementations, the first mechanism may further include a cryopump configured to condense gas within the gas expansion volume
Data Source
AI summary
A gas expansion module for use with semiconductor wafer loadlocks and other regulated-pressure components of semiconductor processing tools is provided. The gas expansion module may be barometrically isolated from the loadlock or other component and pumped down to a vacuum condition while the loadlock is performing operations at a higher pressure, such as ambient atmospheric conditions. After an initial pump-down of the loadlock is performed, the gas expansion module may be fluidly joined to the loadlock volume and the gases within each allowed to reach equilibrium. A further pump-down of the combined volume may be used to bring the loadlock pressure to a desired vacuum condition.