Reticle Inspection via Optical Imaging and Image Analysis
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Solution Overview
Problem
Current inspection methods, such as scanning electron microscopes, are inadequate for accurately measuring complex patterns on reticles due to limitations in measuring complex shapes and suffer from low throughput in the reticle inspection process.
Innovation Solution
A method and system that utilize a microscope to capture top-view images of patterned structures, which are then analyzed by an independent image analysis processor to measure differences between the actual pattern and a predetermined layout, enabling the inspection of both simple and complex patterns in a continuous flow without being bottlenecked by the microscope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scanning electron microscopes are used for inspection, then measurement capability is provided, but throughput is low and complex patterns cannot be accurately measured
Solution Approach 1:
The inspection system is segmented into two independent functional units: (1) a high-speed imaging unit using optical microscopes that captures top-view images of reticle patterns, and (2) a separate measurement unit using a computer to analyze the captured images and measure pattern dimensions. This segmentation allows the imaging unit to operate continuously at high speed while the measurement unit processes data independently, thereby resolving the contradiction between measurement precision and throughput by distributing these functions across separate components that do not bottleneck each other.
2Measurement precision
If scanning electron microscopes are used for inspection, then measurement capability is provided, but complex patterns cannot be accurately measured
Solution Approach 1:
The patent replaces the mechanical/scanning electron microscope-based measurement system with an optical imaging system combined with computer-based image analysis. The optical microscopes capture top-view images of patterns, and the computer analyzes these images using software algorithms to measure both simple and complex pattern geometries. This substitution enables accurate measurement of complex patterns that were previously difficult or impossible to measure with traditional electron microscope methods, while maintaining measurement precision through advanced image processing techniques.
3Loss of information
If microscope-based inspection is used, then pattern visualization is achieved, but the inspection process is bottlenecked by the microscope
Solution Approach 1:
The patent extracts the measurement and analysis functions from the microscope system itself and places them in a separate computer-based processing unit. The microscopes are used solely for capturing top-view images of the reticle patterns at high speed, while the computer independently performs the measurement and analysis of these captured images. This extraction eliminates the microscope as a bottleneck, as the imaging device operates continuously without waiting for measurement cycles, thereby maintaining complete pattern information capture while dramatically improving inspection throughput.
Data Source
AI summary
A method and a system for inspection of a patterned structure are provided. In various embodiments, the method for inspection of a patterned structure includes transferring the patterned structure into a microscope. The method further includes acquiring a top-view image of the patterned structure by the microscope. The method further includes transferring the patterned structure out of the microscope and exporting the top-view image to an image analysis processor. The method further includes measuring a difference between a contour of the top-view image and a predetermined layout of the patterned structure by the image analysis processor.