Semiconductor Pattern Inspection Using Backscattered Electron Contours
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Solution Overview
Problem
Current pattern inspection methods for semiconductor circuits face challenges in accurately and efficiently detecting defects due to variations in secondary electron images caused by electrification and the inability to express three-dimensional configurations of pattern elements using backscattered electron images.
Innovation Solution
A pattern inspection method that uses backscattered electron images to extract contour data, which is then compared with design data to detect defects, while secondary electron images are used for pattern inspection, reducing the impact of electrification and enabling accurate three-dimensional configuration observation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If secondary electron images are used for pattern inspection, then pattern configuration observation is improved, but electrification causes image variation and reduces measurement precision
Solution Approach 1:
The patent combines secondary electron images and backscattered electron images to create a composite image that leverages the advantages of both imaging modes while mitigating their individual disadvantages
Solution Approach 2:
The patent introduces reference pattern images as an intermediary standard for comparison, allowing defect detection without directly relying on potentially electrified specimen images
2Illumination intensity
If backscattered electron detectors are disposed at very small intervals to surround the specimen, then three-dimensional configuration observation is improved, but device complexity and installation area increase
Solution Approach 1:
The patent makes a single backscattered electron detector perform multiple functions by acquiring images at different tilt angles through specimen rotation, eliminating the need for multiple detectors
Solution Approach 2:
The patent introduces dynamic rotation of the specimen stage to enable a single stationary detector to capture images from multiple angular positions, achieving three-dimensional visualization capability
3Loss of information
If multiple backscattered electron images are acquired at different tilt angles, then three-dimensional configuration expression is improved, but inspection time increases
Solution Approach 1:
The patent performs preliminary image acquisition at multiple tilt angles and creates a three-dimensional model before the actual defect inspection process, enabling faster subsequent analysis
Solution Approach 2:
The patent creates a digital three-dimensional model (virtual copy) of the specimen from multiple images, allowing inspection without repeatedly acquiring physical images during the inspection process
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 speedy and accurate semiconductor device examination by extracting contour data from backscattered electron images, reducing the influence of electrification and improving defect detection accuracy.
Implementation Method 1
the specimen is irradiated with an electron beam, backscattered electrons emitted from the specimen are detected by a backscattered electron detector, and backscattered electron image forming means forms a backscattered electron image by using the detected backscattered electrons
Implementation Method 2
secondary electrons emitted from the specimen are detected by a secondary electron detector, and secondary electron image forming means forms a secondary electron image by using the detected secondary electrons
Data Source
AI summary
A pattern data examination method and system capable of accurately and speedily examining a circuit pattern without failing to extract pattern contour data are provided. While pattern comparison is ordinarily made by using a secondary electron image, a contour of a pattern element is extracted by using a backscattered electron image said to be suitable for observation and examination of a three dimensional configuration of a pattern element, and pattern inspection is executed by using the extracted contour of the pattern element. More specifically, pattern inspection is executed by comparing a contour of a pattern element with design data such as CAD data to measure a difference between the contour and the data, and by computing, for example, the size of the circuit pattern element from the contour of a pattern. From two or more backscattered electron images formed by detecting backscattered electrons at two or more different spatial positions, pattern contour data contained in the backscattered electron images may be obtained.