STEM Dose Control for Low-Damage Charged Particle Microscopy
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Solution Overview
Problem
Existing scanning charged particle microscopes cause beam-induced damage to beam-sensitive samples, particularly at low acceleration voltages, and require expert user intervention for optimizing imaging conditions, which are not easily reproducible.
Innovation Solution
A method and system that uses a controller to determine parameter settings for the illuminator and scanning unit based on a desired dose, employing numerical models, active measurements, or calibration data to minimize beam-induced damage, enabling reproducible experiments even for non-expert users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low acceleration voltage is used to reduce knock-on damage, then beam-induced damage is minimized, but imaging conditions become difficult to control and reproduce
Solution Approach 1:
The system automatically adjusts multiple imaging parameters (acceleration voltage, probe current, dwell time, scan rate) based on numerical models and real-time measurements, transforming manual parameter optimization into an automated process that maintains optimal conditions while minimizing beam damage
Solution Approach 2:
The system implements feedback loops using active measurements of beam current and sample response to dynamically adjust imaging parameters, ensuring reproducible conditions and preventing beam-induced damage through real-time monitoring and adjustment
2Object-affected harmful factors
If expert users manually optimize imaging conditions, then beam-induced damage is reduced, but the process requires expert intervention and is not reproducible
Solution Approach 1:
The system performs self-optimization of imaging conditions by automatically adjusting parameters based on numerical models and real-time measurements, eliminating the need for expert user intervention while maintaining optimal imaging quality and minimizing beam damage
Solution Approach 2:
The system pre-calculates optimal imaging parameters using numerical models before actual imaging, and prepares the microscope settings in advance, allowing non-expert users to achieve reproducible results without manual optimization
3Object-affected harmful factors
If acceleration voltage is changed to reduce damage, then knock-on damage decreases, but hours of drift occur and extensive retuning is required
Solution Approach 1:
The system dynamically adjusts acceleration voltage and other parameters during imaging based on real-time measurements and numerical models, allowing continuous optimization without manual intervention or lengthy retuning periods
Solution Approach 2:
The system automatically coordinates changes in multiple parameters (voltage, probe current, dwell time) to compensate for drift effects, maintaining stable imaging conditions without requiring manual retuning
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
The method allows non-experts to achieve reproducible, low-dose scanning transmission microscopy with minimized beam-induced damage, facilitating consistent results across different microscopes and locations.
Implementation Method 1
The interaction may lead to elastically scattered electrons exiting the sample, which may be detected to form a microscopic image
Implementation Method 2
irradiation of the sample precipitates emanation of 'auxiliary' radiation from the sample, in the form of secondary electrons
Implementation Method 3
backscattered electrons
Implementation Method 4
X-rays
Implementation Method 5
cathodoluminescence (infrared, visible and/or ultraviolet photons)
Implementation Method 6
These high energy electrons limit the range of materials that can be studied with high resolution and without damage
Implementation Method 7
other damage mechanisms can increase at these lower acceleration voltages, for example ionization damage
Data Source
AI summary
The disclosure relates to a method for examining a sample in a scanning transmission charged particle microscope. The method comprises the steps of providing a scanning transmission charged particle microscope, having an illuminator and a scanning unit. The method comprises the steps of providing a desired dose for at least a first sample location of the plurality of sample locations; and determining, using a controller of the microscope, a first set of parameter settings for the illuminator and the scanning unit for substantially achieving the desired dose at the first sample location.