Reflective Electron Detector Layout for SE and BSE Separation
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Solution Overview
Problem
Traditional scanning electron microscope detectors face challenges in separating and collecting secondary and backscattered electrons efficiently, leading to reduced resolution and signal strength, especially at small operating distances and low landing voltages.
Innovation Solution
An electron detection device with a reflective energy analyzer, including first and second control electrodes generating an electric field to guide secondary and backscattered electrons to opposite detectors, and a conductive shielding tube to shield the electric field, allowing for improved separation and collection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional detector is placed outside the lens barrel, then the detector can be mounted, but the operating distance becomes very large resulting in reduced resolution
Solution Approach 1:
The detector is nested inside the lens barrel, with the detector body positioned within the cylindrical lens barrel structure. This allows the detector to be located close to the sample while maintaining proper electrical isolation and field shielding, thereby reducing the operating distance and improving resolution without compromising detector functionality.
2Length of moving object
If the detector is placed outside the lens barrel, then mounting is possible, but at small operating distances the mounting becomes inconvenient and mounting accuracy requirements are not met
Solution Approach 1:
The detector assembly is merged with the lens barrel structure, where the detector is positioned inside the lens barrel and electrically connected through the barrel wall. This integrated design eliminates separate mounting requirements and simplifies the overall assembly process while maintaining precise positioning.
3Productivity
If the detector is placed outside the lens barrel, then it can detect electrons, but most electrons enter the lens barrel reversely along the main optical axis and cannot be collected resulting in reduced collection efficiency
Solution Approach 1:
The detector is positioned inside the lens barrel rather than outside, changing the spatial dimension of detection. This internal positioning allows the detector to collect electrons that travel along the main optical axis and reverse into the lens barrel, significantly improving collection efficiency by capturing electrons from all angles within the barrel volume.
4Use of energy by moving object
If a semiconductor backscattered detector is used under low landing voltage conditions, then detection is possible, but the energy of backscattered electrons is low resulting in insufficient detector signal strength
Solution Approach 1:
The detector design incorporates parameters optimized for low-energy electron detection, including specific electrode configurations and electric field distributions that enhance sensitivity to low-energy backscattered electrons. The lens barrel geometry and detector positioning are optimized to maximize collection of low-energy electrons while maintaining adequate signal strength through enhanced detection efficiency.
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
Enhances the separation and collection efficiency of secondary and backscattered electrons, achieving high-resolution imaging and increased signal intensity even at low landing voltages, thereby improving the imaging signal-to-noise ratio.
Implementation Method 1
The first control electrode is configured to generate a first electric field between the first control electrode and the second control electrode. The first electric field is configured to guide the secondary electron to the first detector.
Implementation Method 2
The conductive shielding tube penetrates the first control electrode and the second control electrode in the incidence direction of the electron beam, and the conductive shielding tube is configured to shield an electric field generated by the reflective energy analyzer, allowing the electron beam to pass through
Implementation Method 3
When the electron beam acts on a sample, signal electrons such as Secondary Electrons (SEs) and Backscattered Electrons (BSEs) are generated.
Data Source
AI summary
Provided are an electron detection device and a scanning electron microscope. The electron detection device includes: a reflective energy analyzer including first and second control electrodes that are sequentially arranged in an incidence direction of an electron beam; a first detector disposed at a side of the second control electrode away from the first control electrode; a second detector disposed at a side of the first control electrode away from the second control electrode; and a conductive shielding tube penetrating the first and second control electrodes in the incidence direction and configured to shield an electric field generated by the reflective energy analyzer, allowing the electron beam to pass through and be incident on the target sample. First control electrode is configured to generate a first electric field between the first and second control electrodes. The first electric field is configured to guide the secondary electron to the first detector.