Cavity Decelerating Electrode for High-Resolution Energy Filtering
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Solution Overview
Problem
Existing deceleration type energy filters face challenges in achieving high energy resolution due to energy dispersion issues, which lead to increased device size, reduced current incidence, and contamination, especially when the potential distribution deviates from the optical axis.
Innovation Solution
The energy filter incorporates a decelerating electrode with a single-aperture electrode pair and a cavity portion, along with additional electrodes, to stabilize energy dispersion and reduce size while maintaining high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a deceleration type energy filter is used to simplify device configuration, then device complexity is reduced, but energy resolution deteriorates due to energy dispersion when potential distribution deviates from the optical axis
Solution Approach 1:
The decelerating electrode is divided into multiple independent electrode pairs, each capable of generating deceleration potential. This segmentation allows for better control of the potential distribution and reduces energy dispersion while maintaining structural simplicity.
Solution Approach 2:
Each electrode pair is designed to create a localized deceleration potential region with specific characteristics. By optimizing the local potential distribution at each electrode pair, the overall energy resolution is improved while keeping the global device structure simple.
2Measurement precision
If the decelerating electrode is thickened to increase distance between focal point and energy dispersion point, then energy resolution is improved, but charged particles collide with inner wall causing contamination
Solution Approach 1:
The electrode design incorporates a cavity structure that utilizes the radial dimension to increase the effective distance between the focal point and energy dispersion point without increasing the axial thickness. This prevents particle-wall collisions while achieving the desired energy resolution.
Solution Approach 2:
The cavity portion is nested within the decelerating electrode structure, creating a multi-layered configuration where the cavity provides the necessary spatial separation while the outer electrode structure maintains the deceleration function.
3Measurement precision
If incident charged particles are positioned far from the energy filter to ensure perpendicular incidence, then energy resolution is improved, but device size increases and current incidence decreases
Solution Approach 1:
The electrode pairs are designed with adjustable potentials that can dynamically adapt to different incident particle conditions. This allows the filter to maintain high energy resolution for particles incident at various distances, reducing the need for large separation distances.
4Measurement precision
If multiple electrodes are added to improve energy dispersion control, then energy resolution is improved, but device complexity increases
Solution Approach 1:
Each electrode pair serves multiple functions: generating deceleration potential, controlling local potential distribution, and contributing to overall energy dispersion management. This multi-functionality reduces the need for additional specialized components.
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 configuration enhances energy dispersion within the filter, allowing for a compact high-resolution energy filter that reduces energy dispersion and improves energy resolution, enabling efficient charged particle beam analysis.
Implementation Method 1
A voltage that resists energy of the charged particles is applied to the decelerating electrode
Implementation Method 2
a single-aperture electrode pair with an opening portion... provided in front of the decelerating electrode
Implementation Method 3
a cavity portion having a radius larger than a radius of the opening portion... the cavity being rotationally symmetrical
Data Source
AI summary
A decelerating electrode of an energy filter includes an electrode pair that has an opening and a cavity portion provided in a rotationally symmetrical manner with the center of the opening as the optical axis. Voltages with electric potentials that are substantially the same as that of a charged particle beam are independently applied to both sides of the decelerating electrode. When an electrical field protrudes into the cavity portion, a saddle point having the same electric potential as that of incident charged particles is formed inside the decelerating electrode. The saddle point acts as a high pass filter for incident charged particles at an energy resolution of 1 mV or less. By analyzing charged particles which have been energy-separated, it is possible to measure the energy spectrum and ΔE at the high resolution of 1 mV or less and to obtain an SEM/STEM image with a high resolution.