Projecting apparatus
US4420233A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 24, 1982 |
| Grant date | Dec 13, 1983 |
| Priority date | — |
| Expiry date | May 24, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/70
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A projecting apparatus for forming an image of a mask on a wafer by a projector of a unit magnification reflection system having a concave spherical mirror and a convex spherical mirror. The distance from the projector to the mask or the upper side of a mask holder for holding the mask and the distance from the projector to the wafer are measured. An error of the image-forming position is computed from the distance measurements. At least one of the mask, the wafer and the projector is moved along the direction of projection in a manner to eliminate the error of the image-forming position computed, thus attaining automatic focus adjustment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.