Scanning Electron Microscope Angular Detection Control
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Solution Overview
Problem
Conventional scanning electron microscopes face challenges in detecting reflected electrons at arbitrary emission angles, particularly for samples with complex structures, leading to insufficient information and interference from secondary electrons.
Innovation Solution
The scanning electron microscope is configured with a control electrode, secondary electron conversion electrode, withdrawing electrode, and energy filter to selectively control the detection of reflected electrons by adjusting voltage combinations, allowing for arbitrary selection of the angular range of detected reflected electrons based on sample shape and material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the secondary electron conversion electrode and withdrawing electrode are used to detect reflected electrons, then the detection rate of reflected electrons is improved, but secondary electrons interfere with the detection and reduce measurement precision
Solution Approach 1:
The patent segments the electron detection process by spatially separating reflected electron detection from secondary electron detection. The withdrawing electrode creates an electric field that selectively extracts reflected electrons at specific angles while leaving secondary electrons to be detected by conventional detectors, thus eliminating interference and improving measurement precision while maintaining high detection rate
Solution Approach 2:
The patent applies local quality by creating a localized electric field between the secondary electron conversion electrode and withdrawing electrode that affects only reflected electrons within a specific angular range. This localized field selectively influences reflected electrons without affecting secondary electrons, enabling precise detection of reflected electrons while maintaining overall system productivity
2Loss of information
If reflected electrons at large elevation angles are detected, then surface information and material contrast are improved, but the number of detectable electrons decreases due to angular distribution
Solution Approach 1:
The patent implements dynamics by making the detection angular range adjustable through voltage control of the withdrawing electrode. The electric field configuration can be dynamically changed to detect reflected electrons at different elevation angles, allowing optimization between surface information quality and electron quantity based on specific observation needs
Solution Approach 2:
The patent changes physical parameters by adjusting the voltage applied to the withdrawing electrode to modify the detection angular range. By varying this parameter, the system can selectively detect reflected electrons at different elevation angles, enabling flexible control over the balance between information quality and electron quantity
3Quantity of substance
If the detection angular range is widened to increase electron quantity, then more reflected electrons are detected, but edge contrast from secondary electrons increases and interferes with observation
Solution Approach 1:
The patent extracts reflected electrons from the mixed electron population by using the withdrawing electrode to create an electric field that selectively removes reflected electrons at specific angles. This extraction process separates reflected electrons from secondary electrons, allowing increased detection angular range without incorporating harmful secondary electron edge contrast
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 enables the acquisition of images with enhanced material contrast and pattern shape clarity by selectively detecting reflected electrons at specific angles, improving the scanning electron microscope's ability to handle diverse sample structures.
Implementation Method 1
a secondary electron conversion electrode, between the upper magnetic pole (15) of the objective lens and the detector, for generating the secondary electron by the impact of the reflected electron
Implementation Method 2
accelerates the electron emitted from an electron source of acceleration type or field emission type to form a thin electron beam (primary electron beam) using an electrostatic lens or an electromagnetic lens
Implementation Method 3
accelerates the electron emitted from an electron source of acceleration type or field emission type to form a thin electron beam (primary electron beam) using an electrostatic lens or an electromagnetic lens
Implementation Method 4
The scanning electron microscope is configured to provide a two-dimensional scanned image, which accelerates the electron emitted from an electron source to form a thin electron beam, two-dimensionally scans the primary electron beam on the sample to be observed to detect a secondary signal such as secondary electron and reflected electron
Data Source
AI summary
To provide a scanning electron microscope that can detect reflected electrons of any emission angle, the scanning electron microscope, which obtains an image by detecting electrons from a sample (19) has: a control electrode (18) that discriminates between secondary electrons from the sample (19) and reflected electrons; a secondary electron conversion electrode (13) that generates secondary electrons by the impact of reflected electrons; a withdrawing electrode (12) that withdraws those secondary electrons; an energy filter (11) that discriminates between the secondary electrons withdrawn and electrons reflected from the sample (19); and a control calculation means (36) that selects a combination of voltages applied to the secondary electron conversion electrode (13), the withdrawing electrode (12), and energy filter (11).