Pattern Inspection Apparatus for Sub-Resolution Defect Detection
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Solution Overview
Problem
Existing pattern inspection methods fail to achieve sufficient inspection sensitivity for optically unresolvable patterns due to their miniaturization, making it difficult to optically resolve and inspect such patterns effectively.
Innovation Solution
A pattern inspection apparatus that includes a first inspection data creation section, a delay section, a recognition section, an extraction section, a level difference calculation section, and a determination section, which create and process inspection data to recognize and extract sub-resolution patterns, calculate level differences, and determine defects based on optical images, using both transmitted and reflected light data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical imaging is used to inspect patterns, then the inspection method is simple and non-contact, but the inspection sensitivity becomes insufficient for miniaturized patterns that are optically unresolvable
Solution Approach 1:
The patent introduces a carrier pattern as an intermediary element. The carrier pattern has features that are optically resolvable and serve as a reference framework. By superimposing the target miniaturized pattern onto the carrier pattern and analyzing the combined image, the system can detect sub-resolution defects through their impact on the carrier pattern's known features, thereby achieving high inspection sensitivity without requiring the miniaturized pattern itself to be optically resolvable.
Solution Approach 2:
The patent creates a composite image that copies the carrier pattern's resolvable features along with the target pattern's information. By analyzing the deviations in the copied carrier pattern features within the composite image, the system can infer the presence and characteristics of sub-resolution defects in the target pattern, effectively copying the inspection information without requiring direct optical resolution of the miniaturized features.
2Quantity of substance
If the pattern is miniaturized to advance technology, then the pattern density increases, but the pattern becomes optically unresolvable and inspection fails
Solution Approach 1:
The carrier pattern acts as a mediator that bridges the gap between the miniaturized target pattern and the optical detection system. The carrier pattern's features are designed to be optically resolvable while closely matching the pitch and characteristics of the miniaturized pattern. This intermediary allows the optical system to resolve the carrier features while the superimposed target pattern information remains detectable through its impact on the carrier pattern's resolved features.
Solution Approach 2:
The patent transitions from attempting to resolve the miniaturized pattern in the spatial dimension directly, to analyzing the pattern information in a different dimension through the carrier pattern's feature deviations. By examining how the target pattern modulates the carrier pattern's resolved features, the system extracts inspection information without requiring direct spatial resolution of the sub-resolution target features.
3Manufacturing precision
If conventional inspection methods are used for miniaturized patterns, then the inspection process is simple, but the defect detection accuracy is insufficient
Solution Approach 1:
The carrier pattern serves as an intermediary reference that enables precise defect detection in miniaturized patterns. By comparing the composite image of the target pattern on the carrier pattern against the known carrier pattern features, the system can accurately identify and characterize defects. The carrier pattern's resolved features provide a stable reference framework that amplifies the detectability of sub-resolution defects through their disruptive impact on the carrier pattern.
Solution Approach 2:
The inspection process incorporates feedback through the analysis of the carrier pattern's feature deviations. The system continuously compares the observed carrier pattern features in the composite image against the expected carrier pattern characteristics, using these deviations as feedback to identify and characterize defects in the target pattern. This feedback mechanism enables accurate defect detection by leveraging the carrier pattern's known properties as a reference.
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
The apparatus achieves sufficient inspection sensitivity for optically unresolvable patterns by recognizing and analyzing sub-resolution patterns, enhancing defect detection accuracy and S/N ratio through level difference calculations and logical OR calculations, allowing for finer defect determination.
Implementation Method 1
imaging optical system that forms an optical image of a pattern on a light receiving surface of a CCD sensor
Data Source
AI summary
According to one embodiment, a pattern inspection apparatus includes a first inspection data creation section, a first delay section, a first recognition section, a first extraction section, a first and a second level difference calculation section, a first and a second determination section, and a first logic OR calculation section. The first extraction section extracts data of a sub-resolution pattern from the first inspection data and the first delay data. The first and second level difference calculation section calculate differences between an average output level of a surrounding region for a target pixel of the extracted data from the first inspection data or the first delay data and an output level of the extracted data. The first and second determination sections determine presence or absence of a defect. The first logic OR calculation section calculates logic OR of determination results of the first and second determination sections.