DMAC Aluminum Ion Source With Fluorine Co-Gas for Cleaner Beams
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Solution Overview
Problem
Conventional ion implantation systems face challenges in efficiently generating aluminum ions due to the slow heating and cooling times of external vaporizers and the deposition of insulating compounds on electrodes, leading to high voltage instabilities and variations in ion dosage.
Innovation Solution
The use of gaseous dimethylaluminum chloride (DMAC) as an ion source material, which transitions into vapor at room temperature, combined with a fluorine-containing co-gas to reduce energetic carbon cross-contamination and enhance beam current, allowing for faster species changes and minimizing electrode deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an external vaporizer is used to supply metal salt vapor to the ion source, then adequate vapor pressure can be achieved, but the system experiences slow heating and cooling times, resulting in long wait times for species changes
Solution Approach 1:
The invention extracts the metal salt material from the external vaporizer and places it directly inside the arc chamber where the plasma is generated. This eliminates the need for the external vaporizer's heating and cooling cycles, as the material is introduced directly into the plasma environment where it is immediately vaporized and ionized, thus resolving the time delay issue while maintaining adequate vapor pressure supply.
Solution Approach 2:
The invention uses the plasma itself as an intermediary to vaporize the metal salt material. Instead of relying on an external thermal field from a vaporizer, the high-temperature plasma environment directly vaporizes the material introduced into the arc chamber, eliminating the thermal inertia of the vaporizer system and enabling rapid species changes.
2Temperature
If metal-containing materials are placed inside the arc chamber to withstand high temperatures, then ion beam can be generated, but insulating compounds are deposited on adjacent electrodes, causing high voltage instabilities
Solution Approach 1:
The invention converts the harmful effect of material deposition by using a fluorine-based co-gas that reacts with the metal salt vapor to form volatile fluorinated compounds. These compounds are easily removed from electrode surfaces, transforming the potential harm of deposition into a beneficial self-cleaning effect that maintains high voltage stability while allowing the plasma chamber to operate at high temperatures.
Solution Approach 2:
The invention changes the chemical parameters of the plasma environment by introducing fluorine-containing co-gas. This chemical modification alters the deposition behavior of metal compounds, making them volatile and removable, thus preventing the buildup of insulating layers on electrodes while maintaining the high temperature conditions necessary for ion beam generation.
3Productivity
If aluminum oxide, aluminum fluoride, or aluminum nitride are used as source material, then ions can be sputtered or chemically etched to achieve acceptable beam currents, but insulating compounds deposit on electrodes within 5-10 hours, requiring system shutdown
Solution Approach 1:
The invention uses fluorine-based co-gas to convert the harmful insulating deposits into volatile fluorinated compounds that are easily removed. This self-cleaning mechanism allows the ion source to maintain acceptable beam currents continuously without the 5-10 hour shutdown requirement, significantly extending the operational duration of the ion source components.
Solution Approach 2:
The invention modifies the chemical environment by adding fluorine-containing co-gas, which changes the volatility and adhesion properties of metal compounds. This parameter change prevents the formation of persistent insulating layers, allowing continuous operation at high beam currents and extending the lifetime of ion source components beyond the conventional 5-10 hour limit.
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 enables high beam currents of aluminum ions, reduces energetic carbon contamination, and increases the lifetime of ion source components by eliminating insulating deposits and arcing issues, while allowing for rapid transitions between different ion species.
Implementation Method 1
The DMAC is stored as a liquid that transitions into vapor phase at room temperature at a predetermined negative pressure (e.g., vacuum pressure)
Implementation Method 2
an ion source is configured to receive and ionize the gaseous aluminum-based ion source material and to form an ion beam therefrom
Implementation Method 3
a fluorine-containing co-gas to reduce energetic carbon cross-contamination and enhance beam current
Implementation Method 4
The ion source, for example, comprises an arc chamber, wherein the pressurized gas bottle is configured provide the DMAC to the arc chamber
Data Source
AI summary
An ion implantation system, ion source, and method are provided having a gaseous aluminum-based ion source material. The gaseous aluminum-based ion source material can be, or include, dimethylaluminum chloride (DMAC), where the DMAC is a liquid that transitions into vapor phase at room temperature. An ion source receives and ionizes the gaseous aluminum-based ion source material to form an ion beam. A low-pressure gas bottle supplies the DMAC as a gas to an arc chamber of the ion source by a primary gas line. A separate, secondary gas line supplies a co-gas, such as a fluorine-containing molecule, to the ion source, where the co-gas and DMAC reduce an energetic carbon cross-contamination and/or increase doubly charged aluminum.