Plasma Bridge Neutralization for Low-Energy Ion Beam Stability
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Solution Overview
Problem
Low-energy high-current ion implantation technologies face challenges in space-charge neutralization, particularly in magnetic fields, where existing methods struggle to effectively neutralize space-charge disruptions and maintain beam stability due to low electron production and trapping inefficiencies.
Innovation Solution
The use of plasma consisting of charged argon, xenon, or krypton ions as a low-impedance conduction path between local ground potential and the ion beam, combined with supplementary electron sources and advanced plasma generators like Helicon discharges and hollow cathodes, to establish a stable electron transport and trapping mechanism within the ion beam, ensuring effective space-charge neutralization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrons are introduced for space-charge neutralization in low-energy high-current ion beams, then beam stability is improved, but electron production and trapping efficiencies are insufficient
Solution Approach 1:
The patent uses plasma as an intermediary medium to transport electrons to the ion beam. The plasma, generated by Helicon discharges or hollow cathode sources, serves as a conduit that delivers electrons to the ion beam region, overcoming the inefficiency of direct electron introduction and improving both electron production efficiency and trapping effectiveness.
Solution Approach 2:
The patent applies plasma flow dynamics to transport electrons. By generating plasma with controlled flow characteristics, the system uses the plasma's motion to deliver electrons to the ion beam, analogous to using fluid flow to transport particles. This plasma-driven transport mechanism significantly improves electron delivery efficiency compared to static electron sources.
2Reliability
If plasma generators like Helicon discharges are used to enhance electron transport, then space-charge neutralization is improved, but device complexity increases
Solution Approach 1:
The patent replaces traditional mechanical electron injection systems with plasma-based electron transport. Instead of using complex mechanical electron guns and injection mechanisms, the system uses electromagnetic plasma discharges (Helicon or hollow cathode) to generate and transport electrons, simplifying the overall system architecture while improving neutralization efficiency.
Solution Approach 2:
The plasma generation system serves multiple functions: it generates electrons for neutralization, creates a transport medium for electron delivery, and can be integrated with existing magnetic field configurations. This multi-functionality reduces the need for separate dedicated electron injection systems, thereby managing complexity while maintaining high neutralization efficiency.
3Productivity
If low-impedance conduction paths are established through plasma, then electron transport to ion beam is enhanced, but system stability under varying magnetic field conditions deteriorates
Solution Approach 1:
The patent employs dynamically adjustable plasma generation parameters that can adapt to varying magnetic field conditions. The plasma source characteristics (power, gas flow, frequency) can be modified in real-time to maintain stable electron transport efficiency across different operating conditions, preventing system instability while preserving high productivity.
Solution Approach 2:
The system utilizes changes in plasma generation parameters (such as discharge power, gas pressure, and frequency) to optimize electron transport under different magnetic field strengths. By adjusting these parameters, the system maintains stable and efficient electron delivery to the ion beam across a wide range of operating conditions.
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 enhances space-charge neutralization, maintaining beam stability and throughput even at low energies, reducing ion losses and beam divergence, and enabling efficient operation across a wide range of energies and magnetic field conditions.
Implementation Method 1
The use of plasma consisting of charged argon, xenon, or krypton ions as a low-impedance conduction path between local ground potential and the ion beam
Implementation Method 2
low-impedance conduction path between local ground potential and the ion beam
Implementation Method 3
advanced plasma generators like Helicon discharges and hollow cathodes
Implementation Method 4
advanced plasma generators like Helicon discharges and hollow cathodes
Implementation Method 5
in magnetic fields, where existing methods struggle to effectively neutralize space-charge disruptions and maintain beam stability
Implementation Method 6
counterbalancing space-charge forces is possible by the introduction of electrons and negative ions to the beam
Data Source
AI summary
The fabrication of modern semiconducting integrated circuits often requires implantation steps that involve high currents of low-energy charged dopant atoms. When employing such beams, the addition of electrons or negative ions for neutralizing the effects of space charge is often crucial for achieving success. Without this supplement, ion beams can ‘blow-up’ causing loss of intensity and disruption of beam focusing. In the present disclosure, methods are presented for introducing and constraining neutralizing low-energy electrons and negative ions within the boundaries of ribbon beams within regions of magnetic field deflection. Apparatus is described for maintaining neutralization based upon a reduction of electron losses, plasma bridge connections and secondary electron production. As part of plasma introduction to the deflection region a novel cryogenic pumping apparatus selectively removes neutral atoms from a plasma stream.