An alignment system for align first and second objects using alignment marks
US5028797A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 28, 1989 |
| Grant date | Jul 2, 1991 |
| Priority date | — |
| Expiry date | Sep 28, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7049
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An alignment system for aligning a mask and a wafer into a predetermined positional relationship uses alignment marks provided on the mask and the water. In this system, light from a light source is directed to the alignment marks of the mask and the wafer and, then, the light from these alignment marks is detected by an accumulation type photoelectric converting device, for alignment of the mask and the wafer. The accumulation time of the photoelectric converting device is controlled to be sufficiently longer than or to be equal to a multiple, by an integral number, of the period of relative and natural vibration of the mask and the wafer. This makes it possible to reduce the effect of the relative vibration of the mask and the wafer upon the alignment result and, therefore, makes it possible to enhance the alignment precision.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.