Ion Source Cold Finger for Ion Implantation Glitch Reduction
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Solution Overview
Problem
Conventional indirectly heated cathode (IHC) ion sources in ion implantation systems suffer from non-uniform ion beams and high glitch rates due to films or deposits forming on the ion source chamber and electrodes, leading to reduced performance and lifetime, which complicates the manufacturing of advanced electronic and solar cell devices.
Innovation Solution
The introduction of a diluent, such as phosphine (PH3), is used in conjunction with the feed material, like boron trifluoride (BF3), to ionize and generate ions, which are then selectively directed to the substrate, while the diluent's ions and fragments react with chamber components to form vapor-phase byproducts that can be evacuated, reducing film formation and arcing, thereby improving beam quality and extending ion source lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional indirectly heated cathode ion sources are used to generate high beam current, then ion implantation throughput is improved, but films and deposits form on chamber walls and electrodes causing non-uniform beams and high glitch rates
Solution Approach 1:
A liquid nitrogen-cooled cold finger is introduced as an intermediary component between the ion source chamber wall and the extraction aperture. This cold finger acts as a mediator that captures reactive species and prevents them from depositing on critical surfaces, thereby maintaining beam uniformity and reducing glitch rates while allowing high beam current operation
Solution Approach 2:
The invention converts the harmful reactive species that cause film formation into a beneficial process by directing them toward the liquid nitrogen-cooled cold finger. The reactive species freeze out on the cold surface, preventing damage to the ion source components while the liquid nitrogen continuously traps these species, transforming a reliability problem into a controllable purification mechanism
2Productivity
If high beam current is extracted from the ion source, then ion implantation efficiency is improved, but the lifetime of the ion source is reduced due to increased film formation and arcing
Solution Approach 1:
The liquid nitrogen-cooled cold finger serves as a protective intermediary that extends ion source lifetime by continuously trapping reactive species. This allows the ion source to operate at high beam currents for extended periods without the degradation that would normally limit its operational life
Solution Approach 2:
Liquid nitrogen provides an inert, ultra-low temperature environment that prevents chemical reactions and film formation on the cold finger surface. This inert environment protects the ion source components from reactive species while maintaining high beam current operation, thereby extending ion source lifetime
3Quantity of substance
If feed material is ionized in the ion source chamber, then desired dopant ions are produced, but reactive species form films on chamber walls and electrodes
Solution Approach 1:
The cold finger acts as an intermediary trap that captures reactive species before they can deposit on chamber walls and electrodes. This mediator component allows high concentration of dopant ions to be produced while simultaneously preventing the harmful film formation that would otherwise occur
Solution Approach 2:
The invention extracts harmful reactive species from the ion source chamber environment by directing them to the liquid nitrogen-cooled cold finger where they freeze out. This separation removes the harmful elements from the system while preserving the beneficial dopant ion production
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 significantly reduces glitch rates and increases the lifetime of the ion source, maintaining high beam current and uniformity, even under high ion beam demands, by minimizing the formation of conductive films and arcing, thus enhancing the efficiency and throughput of ion implantation processes.
Implementation Method 1
positioned downstream of the ion source near the extraction aperture... a liquid nitrogen-cooled cold finger positioned downstream of the ion source chamber
Implementation Method 2
a liquid nitrogen-cooled cold finger positioned downstream of the ion source chamber
Data Source
AI summary
Techniques for processing a substrate are disclosed. In one exemplary embodiment, the technique may be realized with an ion implantation system for processing a substrate. The ion implantation system may comprise: an ion source comprising an ion source chamber, the ion source chamber including an ion source chamber wall that define an ion generation region and an extraction aperture, through which ions generated in the ion generation region are extracted; an extraction system positioned downstream of the ion source near the extraction aperture; a material source comprising a fist source containing first material, a second source containing the second material, and a first and second conduits, where the first conduit may be in communication with the first source and the ion source chamber to provide the first material from the first source to the ion source chamber, and where the second conduit may be in communication with the second source and a first region outside of the ion source chamber to provide the second material from the second source to the first region.