Dynamic Knife Edge X-ray Beam Spot Size Control
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Solution Overview
Problem
Current X-ray reflectometry systems face limitations in achieving fine spatial and angular resolution due to the spot size and angular extent of the X-ray beam, which affects the accuracy of thin film analysis.
Innovation Solution
A beam control assembly with a beam blocker and knife edge is used to limit the spot size and angular extent, and a method to adjust the beam's transverse offset at different elevation angles to maximize overlap and minimize effective spot size, combined with a processor to apply transverse corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dynamic knife edge and shutter are used to control the incident beam, then the lateral dimension of the spot is reduced, but the device complexity increases
Solution Approach 1:
The patent employs a dynamic knife edge that can be lowered very near to the sample surface to intercept the incident X-ray beam and shorten the lateral dimension of the spot. The knife edge position is dynamically adjusted based on measurement requirements, allowing fine control of spot size while maintaining system flexibility.
Solution Approach 2:
The knife edge acts as an intermediary element between the X-ray source and the sample, physically blocking portions of the beam to control spot dimensions. This intermediary component enables precise spot size control without requiring complex optical systems.
2Manufacturing precision
If the knife edge is lowered very near to the surface to reduce spot size, then the lateral resolution is improved, but the risk of sample damage increases
Solution Approach 1:
The knife edge is dynamically positioned very near to the sample surface only when needed for high-resolution measurements. The system can raise the knife edge out of the way for high-angle measurements or when sample damage risk is a concern, providing flexible control over the trade-off between resolution and sample safety.
Solution Approach 2:
The system changes the operational parameters by adjusting the knife edge height relative to the sample surface. By varying this parameter, the system optimizes between achieving minimal spot size for high resolution and maintaining sufficient clearance to prevent sample damage.
3Illumination intensity
If the full intensity of the X-ray beam is used for high-angle measurements, then the measurement signal is improved, but the spot size increases
Solution Approach 1:
The knife edge is dynamically raised out of the way for high-angle measurements to allow the full intensity of the X-ray beam to reach the sample. This dynamic adjustment enables the system to optimize beam intensity for high-angle measurements while accepting larger spot sizes, or lower the knife edge when small spot size is prioritized.
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 allows for X-ray analysis with significantly improved spatial and angular resolution, enabling precise characterization of thin film layers with spot sizes as small as a few microns and reduced blurring effects.
Implementation Method 1
The beam blocker contains front and rear slits... The beam limiter has a knife edge, which is transverse to the beam plane and typically protrudes below the lower side of the beam blocker
Data Source
AI summary
A method for analysis of a sample includes directing a beam of radiation to impinge on a target area on a surface of the sample along a beam axis at a plurality of different elevation angles. For each of the different angles, a respective offset of the beam in a direction transverse to the beam axis is determined. While sensing the radiation scattered from the sample at each of the different elevation angles in succession, a transverse correction is applied to at least one of the beam and the sample in order to compensate for the respective offset at each of the different elevation angles.