X-ray Topography Filter and Divergent Beam for Defect Contrast
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Solution Overview
Problem
Current X-ray topography methods face challenges in effectively improving image contrast and detecting defects in crystalline substrates, such as silicon wafers, due to variations in the angle and spacing of crystal lattice planes, leading to shifts in diffraction stripes and reduced signal-to-background ratios.
Innovation Solution
The system employs a source assembly with divergent X-ray beams and a filter to attenuate specific spectral portions, combined with a processor that adjusts the incidence angle and sets a region of interest to enhance the intensity of diffracted signals and reduce background noise, utilizing multiple X-ray tubes and detectors to improve defect detection and image contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a filter is used to attenuate specific spectral portions of the X-ray beam, then the signal-to-background ratio is improved, but the device complexity increases
Solution Approach 1:
A filter is introduced as an intermediary component between the X-ray source and the sample to selectively attenuate specific spectral portions of the X-ray beam. This filter acts as a mediator that modifies the X-ray spectrum to improve the signal-to-background ratio in the detected diffraction patterns, while being a relatively simple passive component that does not significantly increase system complexity.
2Measurement precision
If the incidence angle is adjusted to compensate for shifts in diffraction stripes, then the measurement precision is improved, but the ease of operation decreases
Solution Approach 1:
The system employs feedback control where the processor detects shifts in diffraction stripe positions and automatically adjusts the incidence angle of the X-ray beam to compensate for these shifts. This closed-loop feedback mechanism maintains high measurement precision without requiring manual intervention, thereby preserving ease of operation despite the complexity of the adjustment process.
Solution Approach 2:
The incidence angle of the X-ray beam is made dynamically adjustable rather than fixed, allowing the system to adapt to variations in diffraction patterns. This dynamic adjustment capability enables automatic compensation for stripe shifts while maintaining operational simplicity through automated control.
3Productivity
If multiple X-ray tubes are used to enhance detection sensitivity, then the productivity is improved, but the device complexity and energy consumption increase
Solution Approach 1:
Multiple X-ray tubes are combined in parallel configuration to enhance detection sensitivity and coverage area. By merging the output of multiple tubes, the system achieves improved productivity in terms of detection capability and scanning speed, while sharing common components such as the filter and detector system to mitigate the increase in overall device complexity.
Solution Approach 2:
The multiple X-ray tubes share common supporting infrastructure including the filter assembly, detector system, and control electronics. This multi-functional approach allows each tube to contribute to detection sensitivity while the shared components reduce the net increase in device complexity and energy consumption compared to having completely independent detection systems.
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 significantly enhances the detection sensitivity and quality of crystalline defects by improving the signal-to-background ratio and maintaining high contrast, even with long-range variations in lattice planes, resulting in more accurate defect maps.
Implementation Method 1
The filter is mounted between the source assembly and the first surface, and is configured to attenuate an intensity of a selected spectral portion of the X-ray beam
Implementation Method 2
The detector assembly is configured to detect the X-ray beam that had entered the sample at the first surface, diffracted while passing through the sample
Data Source
AI summary
A system for X-ray topography, the system includes a source assembly, a detector assembly, a filter and a processor. The source assembly is configured to direct at least an X-ray beam to impinge, at an angle, on a first surface of a sample, the X-ray beam is divergent when impinging on the first surface. The detector assembly is configured to detect the X-ray beam that had entered the sample at the first surface, diffracted while passing through the sample and exited the sample at a second surface that is opposite to the first surface, and to produce an electrical signal in response to the detected X-ray beam. The filter is mounted between the source assembly and the first surface, and is configured to attenuate an intensity of a selected spectral portion of the X-ray beam. The processor is configured to detect one or more defects in the sample based on the electrical signal.