Blanks for halftone phase shift photomasks, halftone phase shift photomasks, and methods for fabricating them
US5721075A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 13, 1997 |
| Grant date | Feb 24, 1998 |
| Priority date | — |
| Expiry date | Jan 13, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/32
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention relates a halftone phase shift photomask and a blank therefor, which enables the transmittance of a phase shift portion to be varied even after blank or photomask fabrication, can accommodate to a variety of patterns, and can be fabricated on a mass scale. The exposure light transmittance of a halftone phase shift layer is arbitrarily variable within the range of 1% to 50%, inclusive, by exposing the blank or photomask to a high temperature elevated to at least 150.degree. C., to an oxidizing atmosphere, or to a reducing atmosphere at a step that can provided independent of the steps for film-forming or photomask fabrication step. This enables the exposure light transmittance of the halftone phase shift layer to be changed to any desired value after blank or photomask fabrication, and so an optimal halftone phase shift photomask to be obtained depending on the size, area, location, shape, and the like of the transferred pattern.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.