Phase-shift-moiré focus monitor
US6535280B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 31, 2001 |
| Grant date | Mar 18, 2003 |
| Priority date | — |
| Expiry date | Aug 31, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7049
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An optical monitor includes a body having a first plurality of parallel, substantially opaque, spaced apart lines thereon, and the second plurality of parallel, substantially opaque, spaced apart lines thereon, with a relatively small angle between the first and second pluralities of lines. A an image of the lines of the first plurality thereof is provided on the semiconductor body, upon relative movement of the monitor toward and away from the semiconductor body, the line images move relative to the semiconductor body. The images of the lines of the second plurality thereof provided on the semiconductor body move in a different manner upon relative movement if the monitor toward and away from the semiconductor body: The moiré fringe formed on the semiconductor body from images of the first and second plurality of lines during such movement is analyzed in order to achieve proper focus of the image on the semiconductor body.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.