Electron Microscope Beam Deflection for Off-Axis Signal Detection
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Solution Overview
Problem
The application of a high-voltage electric field to off-axis detectors in electron microscopes affects the path of the main electron beam, reducing its quality and the imaging quality of the microscope.
Innovation Solution
An apparatus and method that deflects the electron beam using centering assemblies to avoid the detector, allowing the electron beam to converge on the sample while generating a return electron signal with lower energy, which is then detected without applying a high-voltage electric field, thereby maintaining beam quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-voltage electric field is applied to off-axis detectors to collect electron signals, then the detection capability is improved, but the quality of the main electron beam deteriorates due to the electric field affecting the beam path
Solution Approach 1:
The patent divides the detection system into two separate assemblies: a first centering assembly that handles the main electron beam and keeps it on the column axis, and a second centering assembly that handles the return electron signal and deflects it to the off-axis detector. This segmentation allows each assembly to be optimized for its specific function without interfering with the other, thus maintaining beam quality while enabling effective signal detection.
Solution Approach 2:
The second centering assembly acts as an intermediary that takes the return electron signal from the sample, deflects it away from the column axis, and directs it to the off-axis detector. This intermediary mechanism enables the detector to receive the signal without needing to apply a high-voltage electric field in the path of the main electron beam, thereby resolving the contradiction between detection capability and beam quality.
2Device complexity
If off-axis detectors are used to detect electron signals, then the detector can be positioned away from the beam path, but high-voltage electric fields are still required which affect the main electron beam quality
Solution Approach 1:
The second centering assembly serves as an intermediary that bridges the gap between the on-axis electron source and the off-axis detector. It actively deflects the return electron signal to the detector's position, eliminating the need for high-voltage electric fields near the detector while maintaining the benefits of off-axis positioning for reduced interference with the main beam.
3Reliability
If the electron beam is deflected away from the column axis to avoid the detector, then the detector can operate without high-voltage electric fields, but additional centering assemblies are required increasing device complexity
Solution Approach 1:
The patent segments the centering function into two distinct assemblies with specialized roles: the first centering assembly maintains the main electron beam on the column axis for optimal beam quality, while the second centering assembly handles the return electron signal by deflecting it to the off-axis detector. This segmentation, while adding a component, creates modular functionality that improves overall system reliability and performance.
Solution Approach 2:
The second centering assembly performs multiple functions: it receives the return electron signal from the sample, deflects the signal away from the column axis, and directs it to the off-axis detector. This multi-functionality reduces the need for additional separate components, thereby managing device complexity while achieving the desired beam quality and detection performance.
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 approach improves the quality of the electron beam and imaging quality by avoiding the impact of high-voltage electric fields on the beam path, enabling effective detection of return electron signals.
Implementation Method 1
a first centering assembly is configured to control an electron beam to be deflected so that the deflected electron beam deviates by a first distance from a column axis
Implementation Method 2
a second centering assembly is configured to control the deflected electron beam to be re-deflected, so that a distance between the re-deflected electron beam and the column axis is less than a preset distance
Implementation Method 3
an objective lens is configured to converge the electron beam deflected by the second centering assembly
Implementation Method 4
the detector assembly is configured to receive the deflected return electron signal
Data Source
AI summary
The present application discloses an apparatus for detecting an electron, a method for detecting an electron signal, and an electron microscope. The apparatus for detecting an electron includes a first centering assembly, a detector assembly, a second centering assembly, an objective lens, and a sample stage for placing a test sample. The first centering assembly is configured to control an electron beam to be deflected, so that the deflected electron beam deviates by a first distance from a column axis of the electron microscope; the second centering assembly is configured to control the deflected electron beam to be re-deflected, so that a distance between the electron beam and the column axis is less than a preset distance; the objective lens is configured to converge the electron beam and act on the test sample, so as to generate a return electron signal.