Hydrogen Bleed Gas for Ion Source Housing
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Solution Overview
Problem
Ion implantation systems face issues with insulating materials like aluminum nitride and alumina producing deleterious arcing and reducing the lifetime of ion sources due to the formation of insulating by-products during aluminum ion implantation, leading to unpredictable beam behavior and frequent maintenance.
Innovation Solution
Incorporating a hydrogen bleed gas system that reacts with undesirable by-products within the ion source housing, using a hydrogen generator positioned at the same electrical potential as the ion source, to prevent the formation of insulating materials and stabilize the ion beam, thereby extending the ion source's lifetime and improving beam currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum nitride or alumina are used as source material for aluminum ion implantation, then aluminum ions can be generated for doping, but insulating by-products are formed that cause arcing and reduce ion source lifetime
Solution Approach 1:
The patent introduces a hydrogen bleed gas that reacts with the harmful insulating by-products (AlFx, AlN, Al2O3) formed during aluminum ion implantation. The hydrogen converts these insulating materials into volatile compounds that can be pumped away, transforming the harmful deposition process into a beneficial cleaning process that extends ion source lifetime and prevents arcing
Solution Approach 2:
The patent changes the chemical environment within the ion source by introducing hydrogen gas at controlled flow rates. This parameter change alters the reaction pathways, causing hydrogen to preferentially react with fluorine and other elements to form volatile compounds rather than insulating materials, thereby preventing the formation of harmful by-products
2Productivity
If etchant gas is introduced to chemically etch aluminum-containing materials, then aluminum ions are ionized and extracted, but insulating material is emitted that causes arcing between components
Solution Approach 1:
The hydrogen bleed gas acts as an intermediary substance that mediates between the etching process and the ion source components. It reacts with fluorine and other reactive species before they can form insulating deposits on electrodes and components, preventing arcing while allowing the etching process to continue generating aluminum ions
Solution Approach 2:
The patent converts the harmful effect of fluorine and reactive species that cause insulating deposits into a beneficial cleaning mechanism. The hydrogen reacts with these species to form volatile compounds (HF, H2O) that are pumped away, turning what would be a depositing process into a cleaning process that protects components from arcing
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 hydrogen bleed gas system effectively mitigates the formation of insulating materials, stabilizes the ion beam, and increases the operational lifetime of the ion source, allowing for higher beam currents and reduced maintenance, while maintaining safety and containment through elevated voltage and conductive tubing.
Implementation Method 1
The gas is configured to react with undesirable by-products of a formation of ions within the ion source
Implementation Method 2
Ion sources in ion implanters typically generate the ion beam by ionizing a source material in an arc chamber
Implementation Method 3
These ions are extracted from the source by an extraction system, typically a set of electrodes, which energize and direct the flow of ions from the source, forming an ion beam
Data Source
AI summary
A terminal system for an ion implantation system has an ion source with a housing and extraction electrode assembly having one or more aperture plates. A gas box is electrically coupled to the ion source. A gas source is within the gas box to provide a gas at substantially the same electrical potential as the ion source assembly. A bleed gas conduit introduces the gas to a region internal to the housing of the ion source and upstream of at least one of the aperture plates. The bleed gas conduit has one or more feed-throughs extending through a body of the ion source assembly, such as a hole in a mounting flange of the ion source. The mounting flange may be a tubular portion having a channel. The bleed gas conduit can further have a gas distribution apparatus defined as a gas distribution ring. The gas distribution ring can generally encircle the tubular portion of the mounting flange.