Retractable Detector for Charged Particle Beam Accuracy
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Solution Overview
Problem
Charged particle beam systems face challenges in accurately measuring specimens due to the obstruction and asymmetrical positioning of detectors by the large tip of the column, which limits the angular coverage of x-ray photons and charged particles emitted or reflected from the specimen.
Innovation Solution
A method and system where a detector is positioned in an inserted position close to the specimen, allowing the primary beam to pass through an aperture at the detector's tip, and then moved to a retracted position, with a detector motion module enabling movement between these positions to optimize beam alignment and detection, while maintaining precise voltage settings to minimize beam deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the detector is positioned close to the specimen to improve detection accuracy, then the angular coverage of x-ray photons and charged particles is improved, but the large tip of the column obstructs the detector and forces asymmetrical positioning
Solution Approach 1:
The detector is made movable between a retracted position (where the column tip obstructs) and an inserted position (where the detector extends past the column tip to achieve symmetrical positioning close to the specimen). This dynamic repositioning allows the system to overcome the static obstruction problem and achieve both close proximity for accuracy and symmetrical positioning for optimal angular coverage.
2Measurement precision
If the detector is positioned in an asymmetrical manner due to column obstruction, then the detector can be placed close to the specimen, but the angular coverage of x-ray photons and charged particles becomes partial and asymmetrical
Solution Approach 1:
The detector moves from a retracted position to an inserted position that extends laterally past the column tip. This dynamic insertion allows the detector to achieve symmetrical positioning relative to the specimen, capturing x-ray photons and charged particles from all angular directions without the asymmetrical obstruction caused by the column.
3Measurement precision
If the detector is moved between inserted and retracted positions, then optimal detection positioning is achieved, but the system complexity increases due to the detector motion module
Solution Approach 1:
A detector motion module is introduced that enables the detector to move between a retracted position (behind the column tip) and an inserted position (extending past the column tip). This single degree of freedom motion mechanism provides the necessary positioning flexibility to achieve symmetrical detector placement while maintaining relatively simple system architecture.
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 enhances the accuracy of charged particle beam measurements by improving the angular coverage and reducing beam deflection, allowing for more comprehensive and precise detection of x-ray photons and charged particles emitted or reflected from the specimen.
Implementation Method 1
detecting, by the detector, x-ray photons and/or charged particles emitted or reflected from the specimen as a result of scanning the specimen with the primary beam
Implementation Method 2
an energy dispersion x-ray detector (EDX) can be used for determining a composition of a specimen. An EDX detector collects x-ray photons emitted from the specimen
Data Source
AI summary
A method for evaluating a specimen includes positioning a detector in an inserted position in which a first distance between a tip of the detector and a plane extending along a surface of the specimen is less than a distance between the plane and a tip of charged particle beam optics. While maintaining the detector at the inserted position, the surface of the specimen is scanned by a primary beam that exits from the tip of the charged particle beam optics. The detector detects x-ray photons and/or charged particles emitted or reflected from the specimen as a result of scanning the specimen with the primary beam. After completion of the scanning, the detector is positioned at a retracted position in which a second distance between the tip of the detector and the plane exceeds a distance between the tip of the charged particle beam optics and the plane.