Off-Axis Dispersing Electron Lens for Energy Spread Filtering
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Solution Overview
Problem
The inherent energy spread of electron beams limits the resolution and performance of electron beam systems, particularly through chromatic aberrations, which reduce image uniformity and resolution in high-resolution applications.
Innovation Solution
A system that includes an electron source, a dispersing electron lens positioned off-axis to introduce spatial dispersion, and an aperture with selectively configurable openings to filter the energy spread of the electron beam, allowing for controlled energy filtering and improved resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the energy spread of the electron beam is reduced using traditional filtering methods, then chromatic aberrations are minimized, but the system complexity and loss of electrons increase
Solution Approach 1:
The dispersing electron lens is configured to perform multiple functions: it introduces spatial dispersion to separate electrons by energy, acts as a focusing element for the filtered beam, and enables adjustable energy filtering. This multi-functionality eliminates the need for separate filtering components, reducing system complexity while maintaining resolution improvement
Solution Approach 2:
The system employs adjustable aperture openings that can be dynamically configured to select different energy ranges. The dispersing electron lens focal power is also adjustable, allowing the system to adapt to different resolution requirements and beam conditions, providing flexible energy filtering without requiring multiple fixed components
2Measurement precision
If the energy spread of the electron beam is reduced through filtering, then image uniformity improves, but electron loss increases
Solution Approach 1:
The system changes the energy parameter of the electron beam by using adjustable aperture openings that select specific energy ranges. By modifying the aperture configuration, the system filters out only the excessive energy spread while preserving the useful electron beam, thus improving image uniformity with minimal electron loss
Solution Approach 2:
The invention replaces traditional mechanical energy filtering systems with an electromagnetic-based dispersing electron lens and aperture system. This substitution allows for more precise control of electron energy distribution and reduces unnecessary electron scattering and loss associated with mechanical filters
3Measurement precision
If a dispersing electron lens is used to introduce spatial dispersion, then energy filtering is achieved, but the device complexity increases
Solution Approach 1:
The dispersing electron lens is merged with the existing electron optics system, combining the dispersion function with the focusing and beam control functions. This integration allows energy filtering to be achieved using components that are already part of the electron beam system, minimizing additional complexity
Solution Approach 2:
The dispersing electron lens serves multiple purposes within the system: it introduces spatial dispersion for energy filtering, focuses the filtered beam, and can be adjusted to optimize performance for different imaging conditions. 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
The system effectively reduces the energy spread of the electron beam, minimizing chromatic aberrations and enhancing the resolution and performance of electron beam systems, particularly in high-resolution applications.
Implementation Method 1
the dispersing electron lens is further positioned to introduce spatial dispersion into the electron beam
Implementation Method 2
the aperture is positioned to pass at least a portion of the electron beam such that the energy spread of the electron beam is filtered
Implementation Method 3
an electron source configured to generate an electron beam having an energy spread
Data Source
AI summary
A selectively configurable system for directing an electron beam with a limited energy spread to a sample includes an electron source to generate an electron beam having an energy spread including one or more energies, an aperture having an on-axis opening and an off-axis opening, a first assembly of one or more electron lenses with selectively configurable focal powers positioned to collect the beam from the source and direct the beam to the aperture, a second assembly of one or more selectively configurable electron lenses positioned to collect the beam, a sample stage, and an electron inspection sub-system including electron optics positioned to direct the beam onto one or more samples. The first assembly includes an off-axis electron lens for interacting with the beam at an off-axis position and introducing spatial dispersion to the beam when configured with a nonzero focal power, thus filtering the energy spread.