Charged Particle Detector Using Wavelength-Differentiated Scintillator Regions
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Solution Overview
Problem
Existing charged particle detectors for SEMs face challenges in being compact, cost-effective, and capable of high spatial resolution while maintaining high response speed and resistance to environmental variations, due to limited scintillators with different emission wavelengths, which complicates the detection of secondary electron emission angles and positions.
Innovation Solution
A charged particle detector configuration using a scintillator with a fluorescent film containing phosphors emitting different wavelengths, a waveguide, and a color filter to select specific wavelengths, along with a photodetector to detect luminescence, allowing for precise position discrimination of secondary electrons without direct exposure to the electron beam, enhancing spatial resolution and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a plurality of charged particle detectors or a two-dimensional detector is provided to detect arrival position of secondary electrons, then spatial resolution is improved, but device complexity and cost increase
Solution Approach 1:
The scintillator is divided into multiple regions along the electron beam incident direction, with each region containing phosphors that emit light at different wavelengths. This segmentation allows position discrimination without requiring multiple detectors or complex two-dimensional detector arrays.
Solution Approach 2:
Different phosphors emitting at different wavelengths are assigned to different regions of the scintillator. By detecting the wavelength of emitted light, the system determines which region was hit by secondary electrons, achieving spatial resolution through color/wavelength differentiation rather than physical detector multiplication.
2Measurement precision
If scintillators with different emission wavelengths are used for position discrimination, then arrival position detection is improved, but availability is limited due to few scintillator types satisfying response speed and stability requirements
Solution Approach 1:
The invention uses composite phosphor materials with different emission wavelengths within the same scintillator structure. This allows customization of emission wavelengths to match available photodetector sensitivity ranges, expanding the selection beyond limited natural scintillator types while maintaining fast response and stability.
Solution Approach 2:
By changing the phosphor material composition and emission wavelength parameters, the system can optimize detection for different secondary electron energies and detection angles. This parameter flexibility overcomes the limitation of fixed scintillator types.
3Area of stationary object
If a compact charged particle detector is arranged in limited space between sample and objective lens, then space utilization is improved, but detector size is constrained
Solution Approach 1:
Instead of expanding the detector area laterally to improve position discrimination, the invention uses the electron beam incident direction (depth dimension) to create multiple detection regions. This allows position discrimination along the beam path without increasing the detector's footprint area.
Solution Approach 2:
Multiple phosphor layers with different emission wavelengths are nested within a single scintillator structure, which itself is positioned in the limited space between sample and objective lens. This nested arrangement maximizes detection capability within the constrained spatial envelope.
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 efficient and reproducible detection of secondary electron positions with improved spatial resolution and resistance to environmental changes, reducing the complexity and cost of detector systems while maintaining high image quality.
Implementation Method 1
a scintillator that is irradiated with charged particles
Implementation Method 2
a fluorescent film which converts lights into lights having another wavelength
Implementation Method 3
a photodetector configured to detect luminescence of the fluorescent film
Data Source
AI summary
A charged particle detector including a scintillator that is irradiated with charged particles, a fluorescent film being in contact with a first surface facing a second surface of the scintillator, the second surface being irradiated with the charged particles, and a photodetector that detects luminescence of the fluorescent film, wherein the fluorescent film has a plurality of regions, the plurality of regions respectively have phosphors that absorb luminescence of the scintillator and emit light with different wavelengths from one another, and a charged particle beam device using the charged particle detector.