Charged Particle Beam Energy Filter Deflection Control
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Solution Overview
Problem
The energy resolution of existing energy filters in charged particle beam devices, such as Scanning Electron Microscopes, varies with the incident direction of electrons, leading to inconsistent performance and difficulties in observation and measurement.
Innovation Solution
A charged particle beam device is configured with a deflector to adjust the incident direction of charged particles to the energy filter, and the deflection condition is set based on changes in brightness to maintain high energy resolution, ensuring precise and stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrons are incident from an oblique direction to the energy filter, then the energy resolution deteriorates, but the device structure remains simple
Solution Approach 1:
The patent applies a retarding field electrode arrangement that forms a potential barrier at the objective lens to retard particles emitted from the sample before they reach the energy filter. This preliminary action ensures that only particles with sufficient energy can overcome the potential barrier and be properly analyzed by the energy filter, thereby maintaining high energy resolution regardless of incident direction.
Solution Approach 2:
The patent changes the energy parameter of particles by applying retarding voltage through the mesh electrode arrangement. This voltage creates a potential barrier that selectively retards low-energy particles while allowing high-energy particles to pass, thus improving energy resolution by filtering particles based on their energy parameter before they reach the detection system.
2Measurement precision
If a retarding field electrode arrangement is applied to form a potential barrier, then energy resolution improves, but device complexity increases
Solution Approach 1:
The mesh electrode arrangement serves multiple functions: it acts as both the energy filter aperture structure and the retarding field generation element. By combining the filtering function and the energy selection function into a single integrated electrode structure, the patent avoids adding separate complex components while achieving improved energy resolution.
Solution Approach 2:
The patent merges the energy filter mesh electrode with the retarding field generation function. The same mesh electrode structure that defines the filter geometry also generates the retarding potential barrier when voltage is applied, thereby combining two previously separate functions into one unified component to reduce overall device complexity.
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 allows for precise control of the energy filter's performance, enabling effective detection of specific energy signals and improving image quality and throughput by maintaining high energy resolution regardless of electron incident direction.
Implementation Method 1
An energy filter is to let electrons having energy of a predetermined value or more pass therethrough selectively... voltage (negative voltage) slightly larger than energy that secondary electrons (SEs) have is applied to a mesh electrode making up an energy filter, thus limiting the reach of secondary electrons or the like
Implementation Method 2
a deflector to deflect charged particles emitted from a sample to an energy filter
Data Source
AI summary
Provided is a charged particle beam device having an energy filter. In one embodiment, a charged particle beam device includes a deflector to deflect charged particles emitted from a sample to an energy filter, and a change in brightness value with the change of voltage applied to the energy filter is found for each of a plurality of deflection conditions for the deflector, and a deflection condition such that a change in the brightness value satisfies a predetermined condition is set as the deflection condition for the deflector.