Continuous alignment target pattern and signal processing
US4578590A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 2, 1983 |
| Grant date | Mar 25, 1986 |
| Priority date | — |
| Expiry date | May 2, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7076
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The present invention is directed to a combination of elements for use in an alignment system for a scanning mask aligner, which include a viewing system having an optical grid, apparatus for moving the mask and wafer alignment patterns across the optical grid, each pattern having front edge portions displaced with respect to rear edge portions in the direction of scanning so that only light corresponding to a plurality of said front edge portions is transmitted through the grid at one time and only light corresponding to a plurality of the rear edge portions being transmitted through the grid at a second later period of time, the grid corresponding to the directions and spacing of the pattern so that light transmitted through the grid is strongly modulated, and circuitry responsive to the transmitted light operative to output alignment signal errors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.