Method and apparatus for reduction-projection type mask alignment
US4153371A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 23, 1977 |
| Grant date | May 8, 1979 |
| Priority date | — |
| Expiry date | Feb 23, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/70
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A mask alignment method of the reduction-projection type comprising the steps of illuminating only regions of alignment patterns formed on a mask and a wafer, before a circuit pattern formed on the mask is projected onto the chips of the wafer through a reduction-projection lens, and aligning the mask and the wafer with each other by detecting the reflected images of both the alignment patterns. The alignment pattern region is illuminated by the light having the same wavelength as the exposure light. In addition, a mask alignment apparatus of the reduction-projection type comprising an illumination device for illuminating the mask. The mask is disposed at a distance from the wafer. The illumination light includes g-line or h-line or a combination of g-line and h-line. The projection lens is interposed between the mask and the wafer so that the circuit pattern formed on the mask is projected on the chips of the wafer on a reduced scale thereby to give the optical printing of the circuit pattern to the wafer. A field diaphragm device is disposed in the vicinity of the mask in order to prevent the exposure of the circuit pattern during the alignment operation. The field diaphragm devi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.