Overlay target and measurement method using reference and sub-grids
US7626702B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 6, 2008 |
| Grant date | Dec 1, 2009 |
| Priority date | — |
| Expiry date | Feb 6, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70633
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method of determining alignment error in electronic substrates comprises providing on a layer of a substrate a first contrasting set of elements forming a first grid pattern having a plurality of grid segments in the x and y directions. The method also includes providing nested within at least one of the first grid pattern segments, on the same or different layer of a substrate, a second contrasting set of elements forming a second grid pattern having a plurality of grid segments in the x and y directions. The method then includes determining the center of the first set of elements in the first grid pattern and determining the center of the second set of elements in the second grid pattern. The method then comprises comparing the centers of the first and second sets of elements and determining alignment error of the first and second grid patterns.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.