Method for aligning first and second objects relative to each other and apparatus for practicing this method
US4811062A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jul 1, 1988 |
| Grant date | Mar 7, 1989 |
| Priority date | — |
| Expiry date | Jul 1, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7049
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In a method for aligning first and second objects relative to each other, according to this invention, the first and second objects are arranged opposite to each other, and are aligned in a direction perpendicular to their opposing direction. A grating pattern is formed, as an alignment mark, on the first object, and a checkerboard-like grating pattern is formed, also as an alignment mark, on the second object. A light beam emitted from an alignment light source is radiated onto the checkerboard-like grating pattern of the second object. The light beam diffracted by the checkerboard-like grating pattern is guided onto the grating pattern of the first object. The light beam diffracted by the grating pattern of the first object is detected by a detector. Since the light beam emitted from the light source is diffracted by the checkerboard-like grating pattern, a relative position of the first and second objects can be detected, irrespective of the distance therebetween. The first and second objects are accurately aligned, based on the detection result. This invention can be applied to a method for aligning a mask and a wafer when a circuit pattern pre-formed on the mask is to be trans…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.