Halftone phase shift photomask, halftone phase shift photomask blank, and methods of producing the same
US5538816A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Apr 11, 1994 |
| Grant date | Jul 23, 1996 |
| Priority date | — |
| Expiry date | Apr 11, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/24868
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A halftone phase shift photomask designed so that it is possible to shorten the photoengraving process, use a production line for a conventional photomask, prevent lowering of the contract between the transparent and semitransparent regions at a long wavelength in the visible region, which is used for inspection and measurement, and also prevent charge-up during electron beam exposure, and that ordinary physical cleaning process can be used for the halftone phase shift photomask. The halftone phase shift photomask has on a transparent substrate (1) a region which is semitransparent to exposure light and a region which is transparent to the exposure light so that the phase difference between light passing through the transparent region and light passing through the semitransparent region is substantially .pi. radians. A semitransparent film that constitutes the semitransparent region is arranged in the form of a multilayer film including layers (3, 4) of chromium or a chromium compound. For example, the layer (3) is formed of chromium oxide, chromium oxide nitride, chromium oxide carbide, or chromium oxide nitride carbide, and the layer (4) is formed of chromium or chromium nitride.…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.