Alignment apparatus
US4170418A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 25, 1976 |
| Grant date | Oct 9, 1979 |
| Priority date | — |
| Expiry date | May 25, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/70
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An alignment apparatus, in which a mask is overlaid on a wafer and a relative displacement between the wafer and a target pattern formed on the mask is detected to effect alignment thereof, comprises a slit frame adapted to reciprocate in a direction substantially parallel to the top surface of the mask and having a slit formed therein, an illumination optical system for illuminating the target pattern, an image formation optical system for forming the image of the target pattern onto the slit of the slit frame, a light sensing element mounted on the slit frame for detecting the target pattern image formed by the image formation optical system through the slit to convert the image into an electric signal, and a displacement detector for detecting the amount of movement of the reciprocation of the slit frame to convert the amount of movement into a position signal which the light sensing element scans, whereby the output signals from the displacement detector and the light sensing element are used to detect the relative position between the mask and the target pattern on the wafer and the mask is moved relative to the wafer such that the relative displacement amount becomes zero.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.