Plasma Electron Flood System for Ion Beam Neutralization
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Solution Overview
Problem
Ion implantation systems face challenges in achieving uniform charge neutralization, particularly with increasing beam currents, which can lead to charging issues and damage to semiconductor devices, and existing solutions like plasma electron flood systems can be costly and complex to maintain.
Innovation Solution
A plasma electron flood system with a housing containing a discharge chamber, an elongated extraction slit, a cathode, and multiple anodes is used to produce a uniform band of electrons for neutralizing ion beams, ensuring consistent charge neutralization across the ion beam width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma electron flood systems are used for charge neutralization, then charge compensation effectiveness is improved, but system complexity and maintenance cost increase
Solution Approach 1:
The patent extracts only the essential electron-generating components (cathode and anode) from complex plasma systems, eliminating unnecessary complexity while maintaining charge neutralization effectiveness. The simplified design removes redundant systems while preserving the core function of electron emission for beam neutralization.
Solution Approach 2:
The patent employs a simple, easily replaceable electron gun design with basic cathode-anode structure that can be quickly replaced if needed, rather than investing in complex, expensive plasma generation systems. This approach prioritizes ease of replacement and lower cost over long-term durability of complex systems.
2Productivity
If beam current is increased to achieve higher dosage, then productivity is improved, but charging effects worsen
Solution Approach 1:
The patent introduces electrons into the ion beam before the beam reaches the semiconductor workpiece, performing charge neutralization in advance. This preliminary action prevents charging effects from occurring during implantation, allowing high beam currents to be used without causing damage to the workpiece.
Solution Approach 2:
The patent uses electrons as an intermediary substance to neutralize the positive charge of the ion beam. By introducing this intermediate charged particle species, the harmful charging effects are counteracted, enabling higher beam currents to be applied safely during ion implantation processes.
3Manufacturing precision
If uniform charge neutralization is achieved across wide ion beams, then implantation uniformity is improved, but electron distribution control becomes more difficult
Solution Approach 1:
The patent shapes the electron beam to match the spatial distribution and dimensions of the ion beam, creating locally optimized electron density at each position across the beam profile. This local matching ensures uniform charge neutralization across the entire wide ion beam width without requiring complex global control systems.
Solution Approach 2:
The patent employs an asymmetric electron gun design with elongated cathode and anode structures that are specifically configured to produce the desired electron spatial distribution. The asymmetric geometry naturally guides electron emission and acceleration to achieve uniform coverage across the wide ion beam without requiring additional complex control mechanisms.
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 provides effective and uniform charge neutralization, reducing the risk of semiconductor device damage and is more cost-effective and simpler to fabricate compared to prior systems.
Implementation Method 1
The cathode emits electrons that are drawn to the plurality of anodes through a potential difference therebetween
Implementation Method 2
A fraction of the emitted electrons are released through the elongated extraction slit as a band of electrons for use in neutralizing an ion beam
Implementation Method 3
providing electric charge of the opposite sign to the workpiece to be implanted... to match the ion beam current with an equal electron current to the workpiece
Data Source
AI summary
A plasma electron flood system, comprising a housing configured to contain a gas, and comprising an elongated extraction slit, and a cathode and a plurality of anodes residing therein and wherein the elongated extraction slit is in direct communication with an ion implanter, wherein the cathode emits electrons that are drawn to the plurality of anodes through a potential difference therebetween, wherein the electrons are released through the elongated extraction slit as an electron band for use in neutralizing a ribbon ion beam traveling within the ion implanter.