BSE-compensated Secondary Electron Image Quality
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Solution Overview
Problem
Secondary electron images are compromised by additional secondary electrons emitted due to backscattered electrons, leading to evaluation process errors in inspection, review, and metrology.
Innovation Solution
A method and system that involve obtaining and processing both secondary electron and backscattered electron images, evaluating multiple correction factors, and applying selected correction factors to reduce backscattered electron-induced errors, resulting in a BSE-compensated SE image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If additional secondary electrons are used for imaging, then image brightness is improved, but image accuracy deteriorates due to BSE-induced errors
Solution Approach 1:
The patent segments the secondary electron signal into two components: surface-emitted SE (useful signal) and additional SE induced by BSE (error signal). By separately identifying and processing these components through correction factors, the method removes the harmful BSE-induced portion while preserving the useful surface SE signal, thus maintaining brightness while improving accuracy.
Solution Approach 2:
The patent converts the harmful effect of BSE-induced additional SE into a beneficial correction process. By using the BSE image to generate correction factors that quantify the BSE-induced error, the method subtracts this error component from the total SE image, transforming the previously harmful additional SE into a measurable and correctable parameter that improves overall image accuracy.
2Measurement precision
If BSE correction processing is applied, then image accuracy is improved, but processing complexity increases
Solution Approach 1:
The patent performs preliminary action by acquiring the BSE image and calculating correction factors before processing the final SE image. The correction factors are pre-computed based on the BSE signal characteristics, allowing the subsequent SE image processing to simply apply these pre-calculated corrections rather than performing complex real-time calculations, thus reducing processing complexity while maintaining accuracy.
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
Improves the quality of secondary electron images by minimizing the impact of additional secondary electrons, thereby reducing evaluation process errors and enhancing accuracy in inspection and metrology.
Implementation Method 1
Secondary electrons (SE) of interest are generally emitted from a thin (for example 2-3 nm) layer at a surface of a sample that is illuminated by an electron beam
Implementation Method 2
The illumination of the sample by the electron beam also results in an emission of backscattered electrons (BSE)
Data Source
AI summary
A method for improving a quality of a secondary electron image of a region of a sample, the method may include obtaining a backscattered electron (BSE) image of the region and a secondary electron (SE) image of the region; wherein the BSE image and the SE image are generated by scanning of the region with an electron beam; processing the BSE image and the SE image to provide a processed BSE image and a processed SE image; and generating a BSE compensated SE image, wherein the generating comprises applying one or more selected BSE correction factors on one or more parts of the processed BSE image.