System and method for visually determining the performance of a photolithography system
US5808731A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 31, 1997 |
| Grant date | Sep 15, 1998 |
| Priority date | — |
| Expiry date | Jul 31, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70633
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The preferred embodiments of the present invention provide a method and apparatus for visually inspecting features on a wafer that are smaller than can be optically resolved using normally using visible light. By providing a method for visually inspecting the features, the overall performance of the fabrication system can be determined. The preferred method patterns resist with two patterns having different spatial frequencies. The patterns combine to form a pattern in the resist that exhibits Moire beats. The Moire beat spatial frequency of the resulting pattern is significantly lower than the two spatial frequencies used, and thus can be visually inspected using light in the visible regions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.