Method and apparatus to improve across field dimensional control in a microlithography tool
US6021009A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 1998 |
| Grant date | Feb 1, 2000 |
| Priority date | — |
| Expiry date | Jun 30, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70241
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A technique for improving across field dimensional control in a microlithography tool. In a lithography imaging process in which a pattern on a mask is projected to form latent images in a photosensitive medium, the critical dimension distribution across the imaging field varies due to scattering and other factors. An optical compensator having gradient neutral density filter properties is used to reduce the intensity of light at those locations corresponding to regions of an imaging field having higher exposure dose. By reducing the intensity of light at the higher dose regions, the overall dose profile is made more uniform, which reduces linewidth variations when devices are fabricated on an semiconductor wafer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.