Inhomogeneous Sample Structure Calculation via Iterative X-Ray Intensity Matching
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Solution Overview
Problem
Existing methods for analyzing inhomogeneous samples using electron-excited x-rays face challenges in determining the structure without measuring beam currents and requiring physical standards, especially in instruments lacking accurate beam current measurement capabilities.
Innovation Solution
A method that calculates the structure of inhomogeneous samples by obtaining measured x-ray intensity data, estimating a beam current factor, calculating effective x-ray intensity data, and iteratively refining the structure until predicted and effective intensity data match within a predetermined similarity criterion, allowing for structure determination without known beam currents or standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional x-ray analysis methods are used requiring beam current measurement and physical standards, then measurement precision is improved, but device complexity and ease of operation deteriorate due to additional measurement requirements
Solution Approach 1:
The invention extracts and eliminates the requirement for beam current measurement and physical standards from the analysis system. By formulating a method that calculates structure directly from x-ray intensity ratios without these external references, the patent removes the complex measurement apparatus and procedures while maintaining analysis accuracy
Solution Approach 2:
The invention creates a computational model that copies the physical interaction processes (electron beam-sample interaction and x-ray generation) through simulation equations. This computational copy replaces the need for physical standards and direct beam current measurement, allowing structure determination through mathematical modeling rather than physical reference measurements
2Measurement precision
If beam current measurement is required for accurate structure determination, then measurement precision is improved, but ease of operation deteriorates due to unstable beam currents in instruments like cold field emission scanning electron microscopes
Solution Approach 1:
The invention implements a feedback mechanism where the calculated structure is used to predict x-ray intensities, which are then compared with measured intensities to refine the beam current factor estimate. This iterative feedback loop allows the system to compensate for beam current instability automatically without requiring direct measurement or manual adjustment
Solution Approach 2:
The system performs self-calibration by using the sample itself as the reference. Through iterative calculation comparing measured and predicted x-ray intensities, the method determines the beam current factor and structure simultaneously without external standards or separate calibration procedures, making the system self-sufficient and easier to operate
3Measurement precision
If physical standards are used for calibration, then measurement precision is improved, but loss of time increases due to additional calibration measurements
Solution Approach 1:
The invention merges the structure determination process with the beam current factor determination into a single integrated calculation. By combining these two previously separate measurement tasks into one simultaneous computational process, the patent eliminates the time required for separate standard measurements while maintaining the precision benefits of calibrated analysis
4Measurement precision
If multiple measurement parameters (beam current, standards) are measured, then measurement precision is improved, but device complexity deteriorates due to additional measurement requirements
Solution Approach 1:
The invention extracts and removes the requirements for beam current measurement and physical standards from the measurement system. By formulating a method that calculates structure directly from x-ray intensity ratios without these external references, the patent removes the complex measurement apparatus and procedures while maintaining analysis accuracy
Solution Approach 2:
The invention creates a computational model that copies the physical interaction processes (electron beam-sample interaction and x-ray generation) through simulation equations. This computational copy replaces the need for physical standards and direct beam current measurement, allowing structure determination through mathematical modeling rather than physical reference measurements
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
Enables the determination of sample structure without measuring beam currents and physical standards, improving analysis feasibility and accuracy in instruments with unstable beam currents, such as cold field emission scanning electron microscopes.
Implementation Method 1
an electron beam is used to cause excitation of x-rays from the sample under known conditions of beam energy and geometry
Implementation Method 2
characteristic x-rays are generated from elements in both the substrate and the various layers
Data Source
AI summary
A method is provided of calculating the structure of an inhomogeneous sample in which an electron beam is used to cause excitation of x-rays from the sample under known conditions of beam energy and geometry with respect to the sample. Notably the beam current is unknown. Measured x-ray intensity data for the sample corresponding to one or more sets of beam conditions and beam currents are firstly obtained, together with comparative x-ray intensity data for samples having known structures. A beam current factor for each beam condition is estimated and effective x-ray intensity data for each of the sets of conditions are then calculated using the measured and comparative x-ray intensity data and the beam current factor. The structure of the sample is then calculated for each of the sets of conditions using the effective x-ray intensity data. Predicting x-ray intensity data are produced corresponding to the calculated structure and compared with the effective x-ray intensity data. These steps are repeated using revised beam current factors until the predicted and effective x-ray intensity data achieve a predetermined similarity condition.