Focusing Particle Trap for Ion Beam Contamination
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Solution Overview
Problem
Ion implantation systems produce contaminant particles that are transported with the ion beam, causing unwanted contamination on semiconductor wafers during fabrication, leading to yield loss and submicroscopic pattern definition issues.
Innovation Solution
A focusing particle trap system is implemented, comprising an entrance electrode, a center electrode, and an exit electrode, generating electrostatic fields to trap unwanted particles within the ion beam, while maintaining a focused beam with minimal loss of beam current, by creating focus and defocus regions to separate ions from contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a particle trap system is implemented to remove contaminant particles from the ion beam, then the contamination on semiconductor wafers is reduced, but the device complexity increases
Solution Approach 1:
The patent introduces an intermediary particle trap system comprising electrodes and electrostatic fields between the ion beam source and the semiconductor wafer. This intermediary structure captures contaminant particles through electrostatic attraction while allowing the ion beam to pass through, thereby reducing wafer contamination without requiring fundamental changes to the ion implantation process itself.
Solution Approach 2:
The particle trap system is segmented into multiple functional components including entrance electrodes, center electrodes, and exit electrodes, each with specific apertures and voltage biases. This segmentation allows the system to handle different aspects of particle separation and beam transmission independently, making the complex function manageable and implementable through modular design.
2Object-affected harmful factors
If apertures are used to filter particles from the ion beam, then contamination is reduced, but beam current is substantially lost
Solution Approach 1:
Instead of using physical apertures that block particles, the patent employs an electrostatic field-mediated approach where charged particles are attracted to electrodes through electric forces. This intermediary field mechanism allows particle removal without physical obstruction, preventing beam current loss while still achieving contamination reduction.
Solution Approach 2:
The system changes the electrical charge parameter of contaminant particles through ionization or charge exchange, enabling them to be manipulated and captured by electrostatic fields. By altering the charge state rather than relying on physical size filtering, the system maintains beam current while removing contaminants.
3Manufacturing precision
If the ion beam is focused to enhance precision, then implantation accuracy is improved, but particles are harder to separate from the beam
Solution Approach 1:
The particle trap system is segmented into multiple functional zones with different electrostatic field configurations. The first particle trap focuses on particle capture while the second particle trap and focusing electrode work together to maintain beam focus. This segmentation allows simultaneous optimization of particle separation and beam focusing without compromise.
Solution Approach 2:
The patent addresses the contradiction by operating in multiple spatial dimensions - using electrostatic fields in the transverse dimension to separate particles while maintaining longitudinal beam focus. This dimensional separation allows particle removal perpendicular to the beam path while preserving beam convergence and implantation precision.
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
The system effectively removes unwanted particles from the ion beam, reducing contamination on semiconductor wafers and enhancing the precision of ion implantation processes, thereby improving the yield and quality of semiconductor devices.
Implementation Method 1
A first electrostatic field is generated from the entrance electrode toward the center electrode and a second electrostatic field is generated from the exit electrode toward the center electrode
Implementation Method 2
generating electrostatic fields to trap unwanted particles within the ion beam
Implementation Method 3
The momentum of the ions in the beam that strike the particles, in turn, cause the particles to be transported with the beam
Implementation Method 4
Selection is accomplished utilizing a mass analyzer that creates a magnetic field through which ions from the ionization chamber travel
Implementation Method 5
The ions leave the ionization chamber at relatively high speeds and are bent into an arc by the magnetic field
Data Source
AI summary
A focusing particle trap system for ion implantation comprising an ion beam source that generates an ion beam, a beam line assembly that receives the ion beam from the ion beam source comprising a mass analyzer that selectively passes selected ions, a focusing electrostatic particle trap that receives the ion beam and removes particles from the ion beam comprising an entrance electrode comprising an entrance aperture and biased to a first base voltage, wherein the first surface of the entrance electrode is facing away from a center electrode and is approximately flat, wherein the second surface of the entrance electrode is facing toward the center electrode and is concave, wherein the center electrode is positioned a distance downstream from the entrance electrode comprising a center aperture and biased to a center voltage, wherein the center voltage is less than the first base voltage, wherein the first surface of the center electrode is facing toward the entrance electrode and is convex, wherein the second surface of the center electrode is facing away from the entrance electrode and is approximately flat, an exit electrode positioned a distance downstream from the center electrode comprising an exit aperture and biased to a second base voltage, and wherein the first surface of the exit electrode is facing toward the center electrode and is approximately flat, wherein the second surface of the exit electrode is facing away from the center electrode and is approximately flat, wherein a first electrostatic field is generated from the entrance electrode toward the center electrode and a second electrostatic field is generated from the exit electrode toward the center electrode; wherein the second base voltage is greater than the center voltage, and an end station that is downstream from the beam line assembly and receives the ion beam.