Vacuum Pumping Arrangement with Ionic Membrane for Hydrogen Removal
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Solution Overview
Problem
In semiconductor fabrication processes, the use of a single primary pump to back multiple secondary vacuum pumps can lead to contamination issues due to the migration of light gases like hydrogen, which can negatively impact the properties of deposited layers and increase the complexity, cost, and size of the pumping arrangement.
Innovation Solution
A method and apparatus that utilize a membrane permeable to hydrogen or oxygen ions, integrated with a vacuum pumping mechanism, to react with hydrogen-containing gases, reducing contamination by converting hydrogen into water vapor and condensing it, thereby improving hydrogen pumping performance while minimizing additional costs and equipment size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single primary pump is used to back multiple secondary vacuum pumps, then device complexity and footprint are reduced, but hydrogen gas migrates backwards through the secondary pumps causing contamination
Solution Approach 1:
A non-porous membrane is introduced as an intermediary component between the primary vacuum pump and the secondary vacuum pump. This membrane selectively permeates hydrogen gas molecules while blocking larger hydrocarbon molecules, allowing hydrogen to be removed from the gas stream without allowing back-migration of contaminated gas to the process enclosure. The membrane acts as a selective barrier that resolves the contradiction by enabling hydrogen removal while preventing contamination.
Solution Approach 2:
The membrane introduces local quality differentiation into the pumping system by creating a selective permeability barrier at a specific location in the gas stream. Different regions of the system have different gas compositions: the process enclosure maintains low hydrogen levels, the membrane selectively transports hydrogen, and the primary pump handles the bulk gas flow. This localized selective transport resolves the contradiction by allowing hydrogen removal without system-wide contamination.
2Reliability
If compression of the secondary vacuum pump is increased to reduce back-migration of hydrogen, then hydrogen pumping performance improves, but cost and size of the pump increase
Solution Approach 1:
The membrane serves as an intermediary that handles the hydrogen removal function separately from the mechanical compression system. Instead of increasing the size and compression capability of the secondary pump, the membrane provides selective hydrogen permeation, allowing the pump to maintain its original size while achieving improved hydrogen pumping performance through the membrane's selective transport mechanism.
Solution Approach 2:
The invention replaces part of the mechanical compression-based hydrogen removal mechanism with a membrane-based selective permeation process. Instead of relying solely on increased mechanical compression to prevent back-migration, the system uses the membrane's selective permeability properties to remove hydrogen at a different stage in the pumping process, thereby avoiding the need for larger, more complex mechanical systems.
3Reliability
If multiple separate secondary pumps are used for different process enclosures, then each enclosure is independently evacuated, but the overall pumping arrangement complexity and footprint increase
Solution Approach 1:
The membrane-based hydrogen removal system provides a universal solution that can be applied to multiple process enclosures sharing a common primary pump. The membrane handles the hydrogen removal function for the entire system, allowing multiple enclosures to be evacuated by a single primary pump without compromising hydrogen management. This multi-functional approach reduces footprint while maintaining reliable evacuation across all enclosures.
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 solution effectively reduces hydrogen contamination and back-migration, enhancing the efficiency and reliability of the pumping system while maintaining low costs and reducing the size of the vacuum pumps, thereby improving the quality of deposited layers in semiconductor fabrication processes.
Implementation Method 1
conveying the gas stream at a sub-atmospheric pressure to one side of a membrane permeable to a selected one of hydrogen ions and oxygen ions
Implementation Method 2
exposing the other side of the membrane to a gaseous source of oxygen ions, so that ions from one of the hydrogen-containing gas and the oxygen source permeate across the membrane
Implementation Method 3
conveying the gas stream through a vacuum pumping mechanism, subsequently conveying the gas stream at a sub-atmospheric pressure
Implementation Method 4
ions from one of the hydrogen-containing gas and the oxygen source permeate across the membrane to react with the other of the hydrogen-containing gas and the oxygen source
Implementation Method 5
converting hydrogen into water vapor and condensing it
Data Source
AI summary
A vacuum pumping arrangement is described for pumping a gas stream containing hydrogen or other hydrogen-containing gas. The arrangement comprises a pumping mechanism for receiving the gas stream and exhausting a pumped gas stream at a sub-atmospheric pressure, and, downstream from the pumping mechanism, an ionic conducting membrane having one side exposed to the pumped gas stream and another side exposed to oxygen or other source of oxygen. In one example, the membrane is permeable to hydrogen, which permeates across the membrane to react with oxygen adsorbed on the other surface of the membrane. In another example, the membrane is permeable to oxygen anions, which permeate across the membrane to react with hydrogen within the gas stream.