Switchable Aperture Mechanism for Charged Particle Beam Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Charged particle beam devices with ring-shaped apertures face difficulties in adjusting the optimal mounting position due to mismatch between the position of maximum current density and brightest beam image, making it hard to align the aperture correctly on the optical axis.
Innovation Solution
Incorporating both a hole-shaped and a ring-shaped charged particle beam aperture, with a drive mechanism to switch between them, allowing for easy adjustment by initially aligning the hole-shaped aperture and then using the ring-shaped aperture at the same position, facilitated by controllers and deflector groups for precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a ring-shaped aperture is used to improve depth of focus, then the depth of focus is improved, but the optimal mounting position cannot be easily adjusted because it does not match the position where the charged particle beam image becomes brightest
Solution Approach 1:
A hole-shaped aperture is introduced as an intermediary tool to facilitate the adjustment of the ring-shaped aperture. The hole-shaped aperture is first positioned at the brightest position of the charged particle beam image, which serves as a reference marker. This intermediary structure enables indirect adjustment of the ring-shaped aperture to the correct optical axis position without requiring direct visualization of the ring aperture itself.
Solution Approach 2:
The hole-shaped aperture is positioned in advance at the optimal location (brightest position of the beam image) before the ring-shaped aperture is adjusted. This preliminary positioning creates a reference framework that guides the subsequent adjustment of the ring-shaped aperture, eliminating the need for complex real-time optimization during ring aperture alignment.
2Reliability
If a ring-shaped aperture is used to eliminate positive spherical aberration, then spherical aberration correction is achieved, but the adjustment complexity increases because the center of the ring aperture must be precisely aligned with the optical axis
Solution Approach 1:
The hole-shaped aperture serves as a mediating reference structure that simplifies the alignment process for the ring-shaped aperture. By first positioning the hole-shaped aperture at the brightest position, operators gain a clear visual reference that guides the subsequent centering of the ring-shaped aperture on the optical axis, reducing alignment complexity.
Solution Approach 2:
The aperture system is segmented into two distinct components: a hole-shaped aperture for reference positioning and a ring-shaped aperture for aberration correction. This segmentation allows each component to perform its specific function independently, with the hole-shaped aperture handling the positioning task and the ring-shaped aperture handling the correction task, thereby simplifying the overall adjustment process.
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
Enables easy and precise adjustment of the ring-shaped aperture on the optical axis, improving usability and alignment accuracy in charged particle beam devices, enhancing image resolution and processing accuracy.
Implementation Method 1
a charged particle beam source 101 that generates a charged particle beam
Implementation Method 2
an objective lens 105 that focuses the charged particle beam on the sample
Implementation Method 3
a ring-shaped aperture has also been known... the depth of focus is improved by using a ring-shaped aperture
Implementation Method 4
applying a voltage between the incident plate and the emission plate leads to divergence for eliminating positive spherical aberration by an electric field formed in the annular opening
Data Source
AI summary
When using a charged particle beam aperture having a ring shape in a charged particle beam device, the charged particle beam with the highest current density immediately above the optical axis, among the charged particle beams is blocked, so that it is difficult to dispose the charged particle beam aperture at the optimal mounting position. Therefore, in addition to the ring-shaped charged particle beam aperture, a hole-shaped charged particle beam aperture is provided, and it is possible to switch between the case where the ring-shaped charged particle beam aperture is disposed on the optical axis of the charged particle beam and the case where the hole-shaped charged particle beam aperture is disposed on the optical axis of the charged particle beam.