Ion Beam Transport Neutral Particle Separator
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Solution Overview
Problem
Conventional ribbon beam ion implanters face challenges in transporting low-energy ion beams due to space charge blow-up and high energy contamination from neutral particles, which degrades beam quality and precision.
Innovation Solution
An ion implantation system that includes an electrostatic deflector to separate ions from neutrals before deceleration, combined with a deceleration system to reduce ion energy, and a mass analyzer to ensure only desired ions reach the substrate, while using cryogenic cooling to reduce background pressure and neutral particle formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ion beam is transported at low energy levels, then ion energy at workpiece is reduced, but space charge blow-up occurs degrading beam quality
Solution Approach 1:
The patent applies preliminary action by removing neutral particles from the ion beam before deceleration occurs. The neutral particle separator is positioned upstream of the decelerator to eliminate neutrals while the beam is still at high energy, preventing subsequent charge exchange reactions that would occur during low-energy transport and cause space charge blow-up.
Solution Approach 2:
The beam transport system is segmented into distinct functional sections: a high-energy section with neutral particle removal, a deceleration section, and a low-energy implantation section. This segmentation allows each section to operate at optimal energy levels, maintaining beam quality during transport while achieving low energy at the workpiece.
2Use of energy by moving object
If conventional deceleration is used without prior neutral removal, then ion energy is reduced, but high energy neutral contamination reaches substrate
Solution Approach 1:
The patent extracts harmful neutral particles from the ion beam using a neutral particle separator positioned before the decelerator. This extraction removes the source of high-energy neutral contamination that would otherwise reach the substrate, while preserving the desired ion beam for implantation.
Solution Approach 2:
Neutral particle removal is performed as a preliminary action before deceleration. By eliminating neutrals while the beam is still at high energy, the system prevents charge exchange reactions during transport that would generate high-energy neutral contaminants at the substrate.
3Ease of manufacture
If ribbon beam technology is used, then cost is reduced, but beam transport at low energy causes space charge blow-up
Solution Approach 1:
The neutral particle separator is integrated into the ribbon beam transport line before the decelerator, performing preliminary neutral removal. This maintains the cost advantages of ribbon beam technology while preventing space charge blow-up during low-energy transport by eliminating the source of charge exchange reactions.
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 enhances ion beam transport efficiency, maintains beam quality, and achieves precise ion implantation with improved uniformity and angular accuracy, reducing the impact of neutral contamination and space charge effects.
Implementation Method 1
transport of the ribbon-shaped ion beam may be corrected by a lens corrector positioned downstream of the decelerator
Implementation Method 2
it is often desirable to transport an ion beam over most beam line elements at a relatively higher energy. A reason for this is that transporting an ion beam at lower energy levels required at a final stage would cause space charge blow-up to occur. Thus, in some ion implanting devices a decelerator is used to reduce ion energy to a desired level just prior to ion beam incidence upon a substrate.
Implementation Method 3
The ion beam may be mass analyzed to eliminate undesired species, accelerated to a desired energy, and then directed onto a target area
Implementation Method 4
Using a properly shaped ribbon beam, uniform dosing density is possible across a work piece with a single one-dimensional pass.
Implementation Method 5
In an ion implantation process, a desired impurity material is typically ionized in an ion source, ions are accelerated to form an ion beam of prescribed energy
Data Source
AI summary
A technique for improved ion beam transport is disclosed. In one particular exemplary embodiment, the technique may be realized as an ion implantation system comprising an ion source for generating an ion beam, a mass analyzer for selecting a desired ion species from ion particles the ion beam, an ion decelerator configured to reduce an energy of ions in the ion beam, an end station for supporting at least one workpiece to be implanted with ions from the ion beam, and a neutral particle separator configured to remove neutrally-charged particles from the ion beam prior to reaching the ion decelerator.