Position detecting method and projection exposure apparatus using the same
US5594549A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 4, 1993 |
| Grant date | Jan 14, 1997 |
| Priority date | — |
| Expiry date | Jun 4, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7049
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A position detecting method includes illuminating a grating mark of an object with monochromatic light; forming an interference image on an image pickup device by using .+-. n-th order light (n=1, 2, 3 . . . ) among reflective diffraction light from the grating mark; integrating an image signal produced by the image pickup device within a two-dimensional window of a predetermined size set with respect to the image signal and along one direction in two-dimensional coordinates, whereby a one-dimensional projection integration signal is produced; transforming, through rectangular transformation, the one-dimensional projection integration signal into a spatial frequency region; selecting, on the spatial frequency region and from the one-dimensional projection integration signal, a spatial frequency component which appears in the interference image due to the periodicity of the grating mark; and detecting the position of the grating mark on the basis of the selection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.