Aluminum Ion Source Co-Gas Chemistry for Stable Beam Current
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Solution Overview
Problem
Existing ion source technologies for generating aluminum ions suffer from reduced beam current and source life due to the buildup of undesired non-aluminum ions and residues, leading to micro arcing, beam non-uniformity, and erosion of arc chamber components.
Innovation Solution
The method involves flowing a combination of fluorine-containing gases, such as PF5, and hydrogen-containing gases into an ion source chamber containing an aluminum dopant source, which enhances the generation of aluminum ions while reducing the production of non-aluminum ions and extending the source life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fluorinated compound (co-gas) is used to generate aluminum ions, then aluminum ion production is achieved, but non-aluminum ionic species build up as residue causing micro arcing and reduced source life
Solution Approach 1:
The patent changes the chemical parameters of the co-gas from traditional fluorinated compounds (BF3, PF3) to sulfur hexafluoride (SF6) or sulfur tetrafluoride (SF4). This parameter change fundamentally alters the chemical reactions in the arc chamber, preventing the formation of tungsten fluoride residues while maintaining aluminum ion generation efficiency, thereby extending source life and eliminating micro arcing
Solution Approach 2:
The patent converts the potentially harmful fluorine reactivity into a beneficial process by using SF6 or SF4 as co-gas. These gases provide fluorine atoms that react with aluminum to produce aluminum ions, while the sulfur-containing byproducts do not form adherent residues on chamber walls or electrodes like tungsten fluorides do, thus transforming a reactive chemistry into a cleaner process
2Quantity of substance
If fluorinated compound reacts with solid aluminum target, then aluminum is released into arc chamber for ionization, but tungsten or molybdenum structures are eroded producing undesired ionic species
Solution Approach 1:
The patent changes the co-gas parameter from traditional fluorinated compounds to sulfur hexafluoride or sulfur tetrafluoride. This change modifies the reaction chemistry such that fluorine atoms are still available to react with aluminum target material, but the resulting sulfur-containing compounds do not react with or erode tungsten and molybdenum chamber structures, eliminating the source of non-aluminum ionic species
3Quantity of substance
If traditional co-gas is used, then aluminum ion generation is maintained, but beam current stability deteriorates over time due to residue deposition
Solution Approach 1:
The patent changes the co-gas composition to SF6 or SF4, which fundamentally alters the deposition chemistry in the arc chamber. This parameter change prevents the formation of adherent tungsten fluoride residues on electrodes and chamber walls, maintaining consistent electrical conditions and beam current stability over extended operational periods
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 approach results in improved beam current stability, extended source life, and reduced non-aluminum ion contamination, leading to more uniform ion beams and enhanced semiconductor device fabrication yields.
Implementation Method 1
The fluorinated compound reacts with (including chemical reaction and by physical sputtering) the solid aluminum
Implementation Method 2
The fluorinated compound reacts with (including chemical reaction and by physical sputtering) the solid aluminum
Implementation Method 3
where the aluminum is ionized
Implementation Method 4
During ionization, the fluorine-containing co-gas becomes ionized or degraded within the arc chamber to produce a neutral or ionized fluorine-containing species
Data Source
AI summary
Described are ion implantation devices, systems, and methods, and in particular to an ion source that is useful for generating an aluminum ion beam.