Photomask blank and phase shift photomask
US5419988A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 5, 1993 |
| Grant date | May 30, 1995 |
| Priority date | — |
| Expiry date | Aug 5, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/24917
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A phase shift photomask and a photomask blank used to produce the same. A dry etching stopper layer, which is disposed between a substrate and a light-shielding layer or between the substrate and a phase shifter layer, is made of either a film mainly composed of tin oxide nitride, which has high etching selectivity and high permeability, or an alumina film formed by sputtering, followed by heat treatment carried out in an oxidizing atmosphere, thereby enabling the required overetching to be satisfactorily performed during etching of the phase shifter layer, and thus making it possible to effect precise phase control. In addition, it is possible to eliminate the occurrence of an in-plane transmittance distribution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.