Photomask for off-axis illumination and method of fabricating the same
US6866968B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 13, 2002 |
| Grant date | Mar 15, 2005 |
| Priority date | — |
| Expiry date | Oct 6, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/34
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A photomask that is capable of implementing off-axis illumination (OAI), and a method of fabricating the same, are provided. The photomask includes a transparent substrate, a plurality of opaque patterns formed on the front surface of the transparent substrate, for defining a floodlighting portion for forming patterns, and a plurality of phase gratings formed on the back surface of the transparent substrate, allowing off-axis illumination (OAI) of an incident light source beyond the OAI limit of exposure equipment, allowing use in the outmost region of an aperture, and allowing modified illumination having a shape suitable for the layout of the opaque patterns.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.