Pattern Inspection Apparatus Distortion Correction
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Solution Overview
Problem
Current pattern inspection methods fail to accurately inspect distorted patterns on photomasks due to misalignment issues, leading to inaccurate defect detection during die-die inspection, especially in semiconductor and LCD manufacturing where pattern sizes are increasingly small and complex.
Innovation Solution
A pattern inspection apparatus and method that includes an optical image acquiring unit, a cut-out unit, a correction unit, and a comparison unit to correct and compare distorted pattern positions on a pixel-to-pixel basis using distortion information, allowing for precise alignment and defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical image data is acquired and compared without position correction, then inspection speed is maintained, but measurement precision deteriorates due to pattern distortion
Solution Approach 1:
The patent applies preliminary action by calculating distortion information and correcting positions of optical image data before performing defect detection. The correction unit pre-processes the image data by adjusting pixel positions based on calculated distortion values, ensuring that patterns are properly aligned before comparison. This preliminary correction enables accurate defect detection without requiring complex real-time adjustment mechanisms during the inspection process.
2Measurement precision
If pattern distortion is corrected using distortion information, then measurement precision is improved, but loss of time increases due to additional correction processing
Solution Approach 1:
The patent calculates distortion information based on the relationship between design data and measured data, then applies this correction in advance to the optical image data. By performing the position correction before defect detection rather than during or after, the system minimizes additional processing time while ensuring accurate pattern alignment for precise measurement.
Solution Approach 2:
The patent creates a corrected copy of the optical image data by adjusting pixel positions according to distortion information. Instead of modifying the original data or performing complex real-time transformations, the system generates a corrected version of the image data that accounts for pattern distortion, enabling accurate defect detection without time-consuming iterative adjustments.
3Measurement precision
If die-to-die inspection is performed without position correction, then productivity is maintained, but measurement precision deteriorates due to misalignment of identical patterns
Solution Approach 1:
The patent performs position correction as a preliminary step before comparing identical patterns at different forming positions. By pre-calculating distortion information and adjusting the positions of optical image data, the system ensures that corresponding patterns are properly aligned before comparison, enabling accurate die-to-die inspection without requiring multiple passes or iterative adjustments that would reduce productivity.
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
Enables accurate inspection of distorted patterns by correcting positional misalignments, thereby improving the detection of defects in small and complex patterns, enhancing the yield and efficiency in semiconductor and LCD manufacturing processes.
Implementation Method 1
A beam is irradiated on the target object from a light source and an illumination optical system. A light transmitted through or reflected by the target object is focused on a sensor through the optical system.
Implementation Method 2
A light transmitted through or reflected by the target object is focused on a sensor through the optical system.
Implementation Method 3
A light transmitted through or reflected by the target object is focused on a sensor through the optical system. An image captured by the sensor is sent to a comparing circuit as optical image (measurement image) data.
Data Source
AI summary
A pattern inspection apparatus includes: an optical image acquiring unit configured to acquire optical image data of a target object on which each of a plurality of identical patterns is respectively formed at a respective corresponding position of a plurality of forming positions with distortion; a cut-out unit configured to cut out a plurality of partial optical image data from the optical image data; a correction unit configured to correct positions of the plurality of partial optical image data by using distortion information from which each amount of distortion of the plurality of identical patterns respectively formed at the respective corresponding position of the plurality of forming positions on the target object can be acquired; and a comparison unit configured to compare a plurality of corrected partial optical image data against each other on a pixel to pixel basis.