Multi-Detector SEM Chemical Imaging With Low-Damage X-Ray Collection
Solution Overview
Problem
Conventional scanning electron microscope (SEM) systems face challenges in acquiring high-quality elemental analysis data efficiently, particularly due to interference from topographic contrast, limited X-ray signal collection, and the need for high beam currents, which can damage specimens and reduce spatial resolution.
Innovation Solution
A method involving multiple X-ray detectors, where one detector is positioned between the specimen and the electron beam source with a filter to reduce electron incidence, and another with a deflector arrangement to mitigate electron interference, allowing for simultaneous acquisition of electron and X-ray data with improved elemental analysis and reduced need for high beam currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single X-ray detector is used with high beam current to improve signal collection, then X-ray signal intensity is improved, but specimen damage increases and spatial resolution decreases
Solution Approach 1:
The patent divides the X-ray detection function into multiple detectors positioned at different locations (e.g., one above and one below the specimen). Each detector collects X-ray signals from different solid angles, allowing the system to achieve high total signal collection efficiency without requiring high beam current that would damage the specimen.
Solution Approach 2:
The patent extends the detection geometry from a single detector position to multiple detectors in three-dimensional space around the specimen. This spatial arrangement enables comprehensive X-ray signal collection from multiple directions simultaneously, improving signal intensity without increasing beam current.
2Device complexity
If a single X-ray detector is used to simplify the system, then device complexity is reduced, but X-ray signal collection efficiency decreases
Solution Approach 1:
The patent segments the detection system into multiple detectors, each responsible for collecting X-rays from a specific direction or solid angle. This segmentation allows each detector to be optimized for its specific position while collectively achieving superior signal collection efficiency compared to a single detector.
Solution Approach 2:
The patent combines the signals from multiple detectors to produce a composite X-ray spectrum or elemental analysis result. This merging of detection capabilities from multiple positions maximizes the total solid angle for X-ray collection while maintaining manageable system complexity through integrated signal processing.
3Loss of information
If topographic contrast is enhanced to improve navigation, then surface orientation information is improved, but atomic number contrast is interfered with
Solution Approach 1:
The patent uses multiple detectors positioned at different angular positions to separately measure X-ray signals. By combining data from detectors with different viewing angles, the system can disentangle topographic effects from compositional effects, preserving both navigation utility and elemental analysis accuracy.
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 enables real-time, high-quality elemental analysis with enhanced navigation and compositional information, avoiding specimen damage and maintaining spatial resolution, while allowing for the detection of a wide range of elements without the need for multiple filters or beam configurations.
Implementation Method 1
a filter member interposed between the first X-ray detector and the specimen and adapted to reduce the incidence of electrons on the first X-ray detector
Implementation Method 2
a deflector arrangement configured to reduce the incidence of electrons on the second X-ray detector
Implementation Method 3
When the beam strikes a specimen, some electrons are scattered back from the specimen (backscattered electrons or BSE) or interact with the specimen to produce secondary electrons (SE) and a number of other emissions such as X-rays
Implementation Method 4
some electrons are scattered back from the specimen (backscattered electrons or BSE)
Implementation Method 5
Each X-ray photon is an energetic particle and the energy is typically converted into a charge, which correlates to the X-ray energy, using a solid-state detector
Data Source
AI summary
A method for analysing a specimen in a microscope is provided. The method comprises: acquiring a series of compound image frames using an electron detector, a first X-ray detector, and a second X-ray detector, wherein the first X-ray detector is positioned between the specimen and an electron beam source from which a focused electron beam emerges towards the specimen, and is provided with a filter member interposed between the first X-ray detector and the specimen and adapted to reduce the incidence of electrons on the first X-ray detector, wherein the second X-ray detector is provided with a deflector arrangement configured to reduce the incidence of electrons on the second X-ray detector, and wherein acquiring a compound image frame comprises: causing the focused electron beam to traverse a region of the specimen; monitoring a set of resulting electrons emitted from a plurality of locations within the region of the specimen, using the electron detector, so as to obtain a first image frame, the first image frame comprising a plurality of pixels corresponding to, and having values derived from the monitored electrons emitted from, the plurality of locations; monitoring first and second sets of resulting X-rays emitted from the plurality of locations using the first X-ray detector and the second X-ray detector respectively, so as to obtain one or more second image frames, each comprising a plurality of pixels corresponding to the plurality of locations and having values derived, in accordance with a first criterion, from monitored X rays characteristic of a respective chemical element and emitted from the plurality of locations, wherein the set of electrons and the first and second sets of X-rays are emitted from the specimen substantially simultaneously; and combining the first image frame and the one or more second image frames so as to produce the compound image frame, such that the compound image frame provides data derived from monitored electrons and X-rays emitted from the plurality of locations within the region, and displaying the series of compound image frames on a visual display, wherein the visual display is updated to show each compound image frame in sequence. A system for analysing a specimen in a microscope is also provided.