Center determination of rotationally symmetrical alignment marks
US7567699B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 7, 2005 |
| Grant date | Jul 28, 2009 |
| Priority date | — |
| Expiry date | Dec 28, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2207/30148
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The invention provides a method for determining the center of a rotationally symmetrical alignment mark thereby using an image recognition software. The alignment mark is recognized by the image recognition software in different orientations by rotating the alignment mark around a symmetry angle with respect to which the alignment mark is rotationally symmetrical, and respective reference points are determined. The center of rotation of the determined reference points corresponds to the center of the alignment mark. Moreover, the invention provides a method for aligning two flat substrates each having a rotationally symmetrical alignment mark and being arranged substantially parallel with respect to each other. To this end, the centers of the alignment marks of the two substrates are determined by means of the method for determining the centers according to the present invention, and the two substrates are aligned by moving at least one of the two substrates in parallel so that the positions of the centers of the alignment marks coincide.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.