Axial Charged Particle Detector for Electron Beam Devices
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Solution Overview
Problem
Existing methods for detecting high-energy signal electrons near the optical axis in charged particle beam devices, such as backscattered electrons, face challenges in uniform axial detection and interference fringe detection due to deflection and energy considerations.
Innovation Solution
A charged particle beam device with a charged particle detecting element positioned on the center axis of the objective lens, allowing for direct detection of high-energy signal electrons and interference fringes without distorting the electron beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a circular aperture on the irradiation axis is used to detect signal electrons, then the detection system is simple, but it is difficult to detect signal electrons near the optical axis
Solution Approach 1:
Instead of placing the detector on the irradiation axis (conventional approach), the invention places the detector on the optical axis of the objective lens, which is a different spatial reference. This inversion of the detection geometry allows signal electrons near the optical axis to be detected effectively while maintaining system simplicity.
2Measurement precision
If deflection is used to detect signal electrons, then detection can be achieved, but the primary electron beam is also affected when signal electron energy is high
Solution Approach 1:
The invention extracts the detection function from the irradiation path by placing the detector on the optical axis where it can detect signal electrons without being in the path of the primary electron beam. This separation eliminates the harmful effect of beam disturbance while maintaining detection capability.
3Measurement precision
If signal electrons are deflected for detection, then detection is possible, but uniform axial detection is difficult
Solution Approach 1:
Rather than deflecting electrons to achieve detection, the invention inverts the approach by positioning the detector on the optical axis to directly receive axially symmetric signal electrons. This maintains uniform detection across the axial direction without introducing asymmetry from deflection.
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 effective detection of high-energy signal electrons and interference patterns, improving spatial resolution and composition information acquisition while minimizing beam distortion.
Implementation Method 1
a charged particle beam source configured to generate a charged particle beam
Implementation Method 2
an objective lens configured to focus the charged particle beam to a sample
Implementation Method 3
detect charged particles generated by an interaction between the charged particle beam and the sample
Data Source
AI summary
Signal electrons with high energy that pass near an optical axis, for example, backscattered electrons or secondary electrons in a booster optical system, can be detected. Therefore, there is provided a charged particle beam device including: a charged particle beam source configured to generate a charged particle beam; an objective lens configured to focus the charged particle beam to a sample; and a first charged particle detecting element disposed between the charged particle beam source and the objective lens and configured to detect charged particles generated by an interaction between the charged particle beam and the sample, in which a detection surface of the first charged particle detecting element is disposed on a center axis of the objective lens.