Self-aligned alternating phase shift mask patterning process
US6824932B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 5, 2002 |
| Grant date | Nov 30, 2004 |
| Priority date | — |
| Expiry date | Dec 21, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/0035
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method and apparatus for making phase shift masks are provided wherein an anti-reflective coating used on an opaque pattern layer of the mask fully covers the opaque pattern layer and has not been etched in the etching process to form the phase shift mask. A two-exposure method to form the phase shift mask is used wherein a photoresist having a defined dose-to-clear level is coated on the surface of the mask and the lower surface of the mask is exposed to a blanket exposure in an energy amount less than the dose-to-clear level. The open areas of the upper surface of the mask to be etched are exposed to an energy dose in an amount less than the dose-to-clear level, with the sum of the amounts of the lower surface energy and upper surface energy being at least the dose-to-clear level. The method and apparatus minimizes and/or avoids etching of the anti-reflective coating.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.