Phase-shift masks and methods of fabrication
US6524755B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 12, 2001 |
| Grant date | Feb 25, 2003 |
| Priority date | — |
| Expiry date | Mar 12, 2021 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/30
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Multilayer film stacks and gray scale processing methods are employed for fabricating phase-shifting masks (PSMs) utilized in lithography. Desired optical transmission and phase-shifting functions of the mask are achieved by controlling the optical properties and thickness of constituent film layers. The mask can be tuned for optimal performance at various wavelengths to an extent beyond that obtainable using a single layer film to control both attenuation and phase shifting of incident light. The processing methods exploit multi-level electron beam or optical beam lithography techniques, and the etch selectivity afforded by selection of appropriate materials for the film stack, to obtain improved yields and reduced processing costs for fabrication of PSMs. In particular, diamond-like carbon (DLC) materials formed by ion beam deposition and having a stress of 1 GPa or less are utilized as etch stop layers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.