Ion Source Split Solenoid Assembly for Uniform Beam
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Solution Overview
Problem
Conventional ion sources struggle to achieve high ion current output while maintaining beam uniformity, especially as silicon wafer sizes increase, due to limitations in magnetic field generation and extraction aperture length.
Innovation Solution
The use of a split solenoid assembly with multiple main coils and trim coils generates uniform magnetic fields within an ion source chamber, allowing for scalable ion source designs with longer extraction apertures and increased ion current, while maintaining beam uniformity through adjustable magnetic field configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If dipole magnets are used to generate magnetic fields in conventional ion sources, then plasma density is enhanced, but beam uniformity deteriorates in elongated ion sources
Solution Approach 1:
The single dipole magnet is segmented into multiple independent magnet modules arranged along the extraction aperture. Each module can be independently controlled to generate magnetic fields with different characteristics, allowing optimization of plasma density in different regions while maintaining overall beam uniformity across the entire extraction aperture.
Solution Approach 2:
Different regions of the extraction aperture are assigned different magnetic field strengths and configurations through the modular magnet system. This allows local optimization where higher plasma density is generated in specific regions while other regions maintain conditions for uniform beam extraction, resolving the contradiction between overall density enhancement and local uniformity.
2Productivity
If the extraction aperture is lengthened to increase ion current output, then current capability is improved, but magnetic field generation becomes insufficient
Solution Approach 1:
The magnetic field generation transitions from a single-point dipole configuration to an extended linear array of multiple magnet modules distributed along the extraction aperture length. This dimensional extension allows the magnetic field generation capability to scale proportionally with the extraction aperture length, maintaining sufficient magnetic confinement and plasma density along the entire length to extract high ion current.
Solution Approach 2:
Multiple magnet modules are combined along the extraction aperture to create a distributed magnetic field generation system. The collective effect of these merged modules provides sufficient total magnetic field strength and proper field distribution across the entire elongated extraction aperture, enabling high current output without magnetic field deficiency.
3Productivity
If the ion source chamber is scaled up to meet throughput demands, then productivity is improved, but beam uniformity deteriorates
Solution Approach 1:
The scaled-up ion source chamber is divided into multiple sections, each served by dedicated magnet modules. This segmentation allows independent optimization of plasma generation and beam extraction in each section, maintaining uniform beam quality across the entire large-scale source while achieving high total throughput through the combined output of all sections.
Solution Approach 2:
The magnetic field parameters (strength, distribution, configuration) are optimized for each region of the scaled-up ion source chamber. By adjusting local magnetic field parameters in different zones of the large chamber, uniform plasma density and beam extraction are maintained across the entire scaled-up system, preventing uniformity deterioration despite the increase in size.
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 enables higher current ion beams with improved uniformity, scaling ion source dimensions to meet increasing throughput demands in semiconductor fabrication without compromising beam quality, as demonstrated by increased current output and consistent magnetic field strength across larger ion source lengths.
Implementation Method 1
solenoid assembly comprising a first solenoid and a second solenoid that are mutually disposed along opposite sides of the ion source chamber
Implementation Method 2
ion source chamber operative to define a plasma therein
Implementation Method 3
beam of ions extracted from the ion source chamber
Data Source
AI summary
An ion source includes an ion source chamber having a longitudinal axis, the ion source chamber operative to define a plasma therein. The ion source also includes a split solenoid assembly comprising a first solenoid and a second solenoid that are mutually disposed along opposite sides of the ion source chamber, where each of the first solenoid and second solenoid comprises a metal member having a long axis parallel to the longitudinal axis of the ion source chamber, and a main coil having a coil axis parallel to the long axis and comprising a plurality of windings that circumscribe the metal member. The main coil defines a coil footprint that is larger than an ion source chamber footprint of the ion source chamber.