Electron Beam Shaping Unit for Space-Charge Compensation
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Solution Overview
Problem
Electron microscopes face limitations in achieving their fundamental resolution due to electron-electron interaction, known as the space-charge effect, which causes beam broadening and reduces temporal and spatial resolution, especially in high-current and low-energy applications.
Innovation Solution
The technique involves shaping the electron beam using a multi-electron wave equation based on the Schrödinger equation with Hartee-Fock approximation, designing a mask to form a Multi Electron Non-Linear (MENL) beam that maintains its shape despite electric charges and diffraction effects, allowing for higher current beams with single-electron resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high current electron beams are used to increase signal-to-noise ratio, then the signal-to-noise ratio improves, but the beam broadens due to space-charge effect reducing resolution
Solution Approach 1:
The patent applies preliminary anti-action by pre-shaping the electron beam wave function to counteract the space-charge effect before it causes beam broadening. The beam is shaped according to a multi-electron wave function that incorporates the repulsive interactions between electrons, allowing the beam to maintain its shape during propagation despite the space-charge effect. This enables high current operation without beam broadening, simultaneously improving signal-to-noise ratio while maintaining spatial resolution.
2Loss of time
If multiple electrons are used to reduce integration time, then the response time improves, but the beam broadening due to electron-electron interaction reduces resolution
Solution Approach 1:
The patent uses preliminary anti-action by designing the beam wave function in advance to compensate for electron-electron repulsion. The multi-electron wave function is calculated to include the effects of space-charge, and the beam is shaped accordingly before propagation. This allows multiple electrons to be used for fast imaging while the pre-built-in compensation prevents beam broadening, maintaining spatial resolution even at high currents and short integration times.
3Measurement precision
If low energy electron beams are used for certain applications, then the sensitivity to sample interactions improves, but the beam is more susceptible to space-charge broadening
Solution Approach 1:
The patent applies preliminary anti-action by shaping low energy electron beams with multi-electron wave functions that account for space-charge effects. The beam shaping is performed before the electrons interact with the sample, pre-compensating for the repulsive forces that would otherwise cause broadening. This enables low energy beams to maintain small spot sizes while still providing high sensitivity to sample interactions, as the space-charge broadening is counteracted by the pre-shaped wave function.
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 electron microscopes to operate with high-intensity beams while maintaining resolution, increasing signal-to-noise ratio and reducing integration time, allowing for better monitoring of time-dependent events without compromising spatial resolution.
Implementation Method 1
The e-beam interacts with the sample and produces an image that contains spatial information about the sample
Implementation Method 2
a mask unit configured for affecting propagation of electrons therethrough to thereby form at far field thereof a propagating electron beam having radial shape
Data Source
AI summary
An electron beam shaping unit for use in electron beam column and a method for designing thereof is presented. The electron beam shaping unit is configured for affecting electron beams of high density or strong electron-electron repulsion. These 5 beams can always be modeled with multi electron wave function. The electron beam shaping unit comprises a mask unit configured for affecting propagation of electrons therethrough to thereby form a propagating electron beam having, at far field, radial shape as determined by multi-electron non-linear function being an eigen function determined by a multi-electron Hartree-Fock Hamiltonian.