Reference Image Contour Generation for Wafer Inspection
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Solution Overview
Problem
Current wafer inspection systems face challenges in accurately determining contour lines for integrated circuit features due to noise in scanning electron-beam microscope images, leading to unreliable edge extraction and potential false contour lines.
Innovation Solution
A method and apparatus for generating reference image contours by simulating photolithographic and photoresist effects on design target information, using edge detection to create a reference image contour pattern that guides the identification of accurate edges in scanned images, thereby improving the accuracy of contour pattern generation and defect inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If edge extraction is performed directly on scanned images, then the process is simple and fast, but the accuracy deteriorates due to noise causing false contour lines
Solution Approach 1:
The patent applies preliminary action by generating a reference image contour pattern before performing edge extraction on scanned images. The reference image, created through photolithographic simulation, pre-establishes the expected contour lines and feature locations. This preliminary reference guides the subsequent edge detection process, ensuring that only valid edges corresponding to actual circuit features are extracted, while noise-induced false edges are filtered out through comparison with the reference pattern.
2Measurement precision
If photolithographic simulation is used to generate reference images, then contour line accuracy is improved, but the inspection time increases
Solution Approach 1:
The patent applies copying by creating a reference image that replicates the expected appearance of circuit features after photolithographic processing. Instead of analyzing each scanned image from scratch, the system generates a simulated reference copy of what the features should look like based on design data and photolithographic models. This reference copy serves as a template for rapid comparison and validation during actual inspection, significantly reducing the computational burden and time required for accurate edge detection in production scanning.
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 enhances the accuracy of contour pattern generation and defect detection by filtering out noise and ensuring that only actual edges are measured, improving the reliability of wafer inspection systems.
Implementation Method 1
generating a reference image based on a simulation of photolithographic effects on the mask pattern
Implementation Method 2
generating a reference image based on a simulation of photoresist effects on the mask pattern
Implementation Method 3
a scanning device such as a scanning electron-beam microscope (SEM) to generate die images
Data Source
AI summary
A method for reference image contour generation includes generating a mask pattern based on design target information, generating a reference image based on a simulation of photolithographic effects on the mask pattern, generating a reference image contour pattern based on edge detection in the reference image, and generating a scanned image contour pattern as a function of the reference image contour pattern and a scanned image of an integrated circuit.