Lithography mask with a .pi.-phase shifting attenuator
US4890309A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 25, 1987 |
| Grant date | Dec 26, 1989 |
| Priority date | — |
| Expiry date | Feb 25, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70283
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The mask includes an attenuator which passes a fraction of the incident electromagnetic radiation and phase shifts the radiation relative to the radiation passing through open features of the mask by approximately an odd multiple of .pi. radians. This phase shifting of light passing through the attenuator by .pi. radians reduces the edge blurring that results from diffraction effects. The present invention steepens the slope of the intensity profile at the edges of features in x-ray lithographic replication relative to the slope obtained with a conventional x-ray mask. The steeper slope is a highly significant advantage because it permits improved linewidth control.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.