Wire-Fed Metal Dopant Ion Source for Stable Beam Current
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Solution Overview
Problem
Existing ion sources face challenges when using solid metal dopants due to issues with vaporizers operating at high temperatures, heat shielding, condensation, and low vapor pressure, which can lead to contamination and reduced beam current.
Innovation Solution
An ion source with a material delivery system that introduces a metal dopant in the form of a wire into the arc chamber, where it can be sputtered or chemically etched, allowing for controlled delivery and preventing liquid metal spills.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a vaporizer is used to deliver solid metal dopant, then the dopant can be vaporized and delivered to the ion source, but the vaporizer cannot operate at temperatures greater than 1200 Celsius due to material limitations
Solution Approach 1:
The patent extracts the dopant material from a vaporizer system and delivers it directly as a solid wire into the ion source chamber, eliminating the vaporizer component entirely. This allows the dopant to be introduced in solid form without requiring high-temperature vaporization, thus resolving the contradiction between operating temperature and reliability.
Solution Approach 2:
The patent changes the physical state parameter of the dopant delivery system from vaporized gas phase to solid wire form. By controlling the delivery rate of the solid wire and using a spool mechanism, the system maintains reliable operation without requiring the vaporizer to operate above 1200 Celsius.
2Quantity of substance
If a block of pure dopant metal is used as the target, then the dopant species is readily available, but the metal may melt or splatter due to low melting temperature, leaving deposits on the interior of the ion source
Solution Approach 1:
The patent segments the dopant metal into a wire form that can be controlled and delivered incrementally. The wire is fed through a conduit at a controlled rate, preventing the entire block from being heated simultaneously. This segmentation approach maintains dopant availability while preventing melting and splatter contamination.
Solution Approach 2:
The patent implements preliminary cooling of the wire before it enters the ion source chamber. A cooling element is positioned to cool the wire just prior to its introduction into the hot plasma environment, ensuring the wire remains solid and does not melt or splatter, thus preventing contamination.
3Productivity
If the wire delivery rate is increased to maintain beam current, then the desired beam current is achieved, but liquid metal may be spilled in the arc chamber
Solution Approach 1:
The patent applies preliminary cooling to the wire before it enters the arc chamber. This pre-cooling ensures that even at increased delivery rates, the wire remains below its melting point when introduced into the plasma, preventing liquid metal spill while maintaining the necessary beam current.
Solution Approach 2:
The system uses feedback control to monitor the wire delivery rate and adjust it to maintain beam current while preventing liquid metal spill. The controller monitors conditions in the arc chamber and adjusts the wire feed rate accordingly, ensuring optimal performance without contamination.
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 enables the use of metal dopants without contamination, maintains a desired beam current, and allows for easy replacement of the dopant without breaking vacuum, addressing the limitations of existing technologies.
Implementation Method 1
The wire is introduced through an opening in one wall of the arc chamber and is sputtered or chemically etched by the plasma
Implementation Method 2
The wire is introduced through an opening in one wall of the arc chamber and is sputtered or chemically etched by the plasma
Implementation Method 3
The filament emits thermionic electrons, which are accelerated toward and heat the cathode, in turn causing the cathode to emit electrons into the arc chamber
Data Source
AI summary
An ion source that includes a material delivery system to deliver a metal dopant in the form of a wire to the ion source is disclosed. The wire is introduced through an opening in one wall of the arc chamber and is sputtered or chemically etched by the plasma. The rate at which the wire is delivered may be controlled so as to maintain a desired beam current without causing any liquid metal to be spilled in the arc chamber. In some embodiments, the wire may be heated or cooled prior to entering the ion source. In some embodiments, a dopant power supply may be employed to supply a bias voltage to the wire. A controller may be used to control various parameters associated with the metal dopant, including delivery rate, dopant voltage and dopant temperature.