Defect Inspection Using Design Image Pairs for Mask Accuracy
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Solution Overview
Problem
In semiconductor device manufacturing, defect inspection using die-to-database inspection is challenging due to the difficulty in generating accurate masks from real images, as patch images are influenced by surrounding patterns, leading to variations in luminance and color, making it hard to find suitable design images for comparison.
Innovation Solution
A defect inspection apparatus that stores dictionary data with pairs of design and real images, where the design images include information from a wider area than the real images, allowing for the generation of a pseudo real image as a mask by searching for similar design images and pasting corresponding real images onto the inspection object's design image, effectively addressing the issue of pattern influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If patch images are cut from real images for mask generation, then the mask can be created from actual product images, but the patch images are influenced by surrounding patterns causing variations in luminance and color
Solution Approach 1:
The patent introduces design images as an intermediary between the inspection object and the mask generation process. Instead of directly using patch images from real images (which are influenced by surrounding patterns), the system uses design images that represent the ideal circuit pattern as a mediator. The comparison is made between the inspection object and the design image, with the design image serving as the reference standard that is not affected by variations in imaging conditions or surrounding patterns.
Solution Approach 2:
The patent segments the inspection process into multiple stages: (1) cutting patch images from real images for initial analysis, (2) comparing with design images to identify potential defects, and (3) generating masks based on the comparison results. This segmentation allows the system to handle the complexity of pattern influence by processing different image types separately at different stages, using design images as the stable reference segment.
2Adaptability or versatility
If patch images from different design images are used to generate masks, then more variety in inspection patterns is achieved, but the real images differ in luminance or color making it difficult to generate appropriate masks
Solution Approach 1:
The patent applies local quality by using design images that are specifically tailored to match the local characteristics of each inspection region. Instead of using a single uniform mask generation approach, the system selects and compares with design images that correspond to the specific circuit pattern being inspected, ensuring that the reference standard matches the local requirements of each inspection area.
Solution Approach 2:
The patent changes the reference parameter from real image patch characteristics (which vary in luminance and color) to design image characteristics (which represent ideal, consistent patterns). By switching the reference standard to design images with controlled and consistent parameters, the system eliminates the problem of luminance and color variations while maintaining adaptability to different inspection patterns.
3Measurement precision
If design images with wider area information are used for comparison, then more context is available for accurate matching, but the data processing complexity increases
Solution Approach 1:
The patent segments the large design images into smaller patch images that can be efficiently processed and compared. By dividing the wide-area design images into manageable patches, the system maintains the benefit of having contextual information from the larger design while reducing the computational complexity of processing and comparing the entire large image at once.
Data Source
AI summary
According to one embodiment, a defect inspection apparatus includes a storage and a processor. The storage stores dictionary in which a first design image generated by software is associated with a first real image corresponding to the first design image. The processor acquires a second design image generated by the software. The processor searches for a similar first design image similar to the second design image. The processor generates a reference image that is a pseudo real image of a second inspection object, based on the second design data and free of defect, by using the first real image associated with the similar first design image. The first design image includes information of an image area wider than the first real image.