Anchor’s seminal product was a Post-RET Verification (PRV) tool that employs lithography models to simulate printed wafer images and identify weak patterns. This is an image-intensive application that demonstrates Anchor’s longstanding expertise in image processing technology.
Today, Anchor understands the importance of applying image processing technology to the production Fab, and has developed products such as D2DB-Image Explorer and D2DB-Pattern Monitor.
In this section we examine some of the image processing capabilities offered by Anchor across various products.
There is a wealth of information contained in high resolution images, but the information is not fully exploited, and many images such as SEM Non-Visual (SNV) are simply discarded, resulting in a significant reduction in the return on investment of expensive imaging tools.
Some of Anchor’s image processing capabilities for the Fab include:
- Pattern (contour) extraction.
- Contour to layout conversion.
- Contour alignment to design.
- Contour search.
- Layout to contour conversion.
- Defect detection.
- Image stitching.
These are described in the sections that follow.
Contour alignment is designed for use cases where a starting location is known, such as a defect coordinate. Defect coordinates contain some amount of stage and measurement error, which means that the coordinate itself cannot be trusted as the true location of the defect. By aligning the image to design, the true coordinate can be determined.
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Given an image, contour extraction is first performed to lift the pattern out of the image. The resulting contour is then converted to resemble Manhattan geometry, as shown here.
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