Formation of silicon nitride film for a phase shift mask at 193 nm
US6319568A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 13, 1999 |
| Grant date | Nov 20, 2001 |
| Priority date | — |
| Expiry date | Dec 13, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/32
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A half tone phase shift mask material, suitable for use at 193 nm is disclosed. It comprises a layer of nitrogen rich silicon nitride that was formed by subjecting a mixture of a nitrogen bearing gas, such as nitrogen and/or ammonia, with a silicon bearing gas, such as silane, to a plasma discharge. Provided the ratio of the nitrogen bearing to the silicon bearing gases is about 10 to 1, films having the required optical properties at 193 nm are formed. These properties are a reflectance that is less than 15% and a transmittance that is between 4 and 15%. Related optical properties, namely an extinction coefficient of about 0.4 and a refractive index of about 2.5, are also closely approached. Additionally, the films are stable under prolonged UV exposure and exhibit good etch behavior.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.