Automatic wafer alignment system
US4325077A · kind A · utility
14Cited by
5References
15Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | May 19, 1980 |
| Grant date | Apr 13, 1982 |
| Priority date | — |
| Expiry date | May 19, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7076
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In the alignment system disclosed, herein a raster scanned video signal representing a selected portion of the wafer surface is analyzed for diagonal reference lines or features on the surface of the wafer utilizing a swept gating technique which extracts desired image features from an obscuring or noisy background. A given point on the wafer surface is determined by locating two oppositely-inclined diagonal features, the point being defined by their intersection. These two features are searched for simultaneously and independently, minimizing the search time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.