Split Acceleration Tube for Multibeam Secondary Electron Separation
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Solution Overview
Problem
Charged particle microscopy systems face challenges in efficiently separating and detecting secondary electrons from multiple beamlets in multibeam systems, particularly when dealing with non-conducting or dielectric samples, which are sensitive to bias voltages.
Innovation Solution
A split acceleration tube system with a separator and charged-particle optical elements redirects secondary electrons into a secondary column, accelerating them to higher energy levels to reduce spatial overlap and interference, while using a Wien filter to separate electrons based on velocity direction, without applying bias to the sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bias voltage is applied to separate secondary electrons from multiple beamlets, then separation efficiency improves, but non-conducting or dielectric samples are damaged or distorted
Solution Approach 1:
The patent introduces an intermediary electrostatic lens system between the sample and the detector that separates secondary electrons based on their energy and angle without requiring bias voltage on the sample. The lens uses electric fields generated by adjustable electrodes to deflect electrons, achieving separation while keeping the sample unbiased and intact.
Solution Approach 2:
The patent changes the parameters of the electrostatic field (voltage on lenses, electrode potentials) to control the trajectory and separation of secondary electrons. By adjusting these field parameters rather than applying bias to the sample, the system achieves electron separation while preserving sample integrity.
2Productivity
If multiple beamlets are used to increase productivity, then analysis speed improves, but cross-talk between beamlets increases
Solution Approach 1:
The patent extracts secondary electrons from each beamlet's interaction region using electrostatic lenses that are spatially separated and independently controlled. Each lens system captures electrons from its associated beamlet, physically separating the detection paths and eliminating cross-talk while maintaining high productivity through parallel processing.
3Device complexity
If secondary electrons are detected directly without acceleration, then system simplicity is maintained, but spatial overlap and interference increase
Solution Approach 1:
The patent introduces dynamic electrostatic lens elements with adjustable potentials that can adaptively control electron trajectories. This dynamic control allows the system to achieve precise spatial separation and focus of accelerated secondary electrons, improving resolution while keeping the added complexity manageable through programmable control.
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 enhances sensitivity, robustness, and flexibility in multibeam systems, allowing analysis of non-conducting samples by reducing chromatic and geometrical aberrations, and minimizing cross-talk between beamlets.
Implementation Method 1
accelerating them to higher energy levels to reduce spatial overlap and interference
Implementation Method 2
using a Wien filter to separate electrons based on velocity direction
Implementation Method 3
configured to apply a deflection force to electrons having a negative velocity in a first direction. The deflection force can redirect the electrons toward a second direction
Data Source
AI summary
Embodiments of the present disclosure include systems, methods, algorithms, and non-transitory media storing computer-readable instructions for charged particle imaging and microanalysis. A charged particle beam system can include an objective lens assembly, defining an aperture collocated with a first axis. The system can include a bifurcated acceleration tube. The acceleration tube can include a primary segment, a secondary segment, intersecting the primary segment, the secondary segment being oriented at an angle, a, relative to the first axis, and a common segment, disposed at least partially in the aperture. The system can include a separator. The separator can include one or more charged-particle optical elements disposed in the common segment and configured to apply a deflection force to electrons having a negative velocity in a first direction. The deflection force can redirect the electrons toward a second direction substantially aligned with a second axis.