Reticle with structurally identical inverted phase-shifted features
US5348826A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 2, 1993 |
| Grant date | Sep 20, 1994 |
| Priority date | — |
| Expiry date | Feb 2, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70641
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A phase-shifted reticle with patterns proximate each other having inverted phases for the features and phase-shifting elements, and methods of fabricating the reticle. Each of the patterns and inverted patterns are structurally identical with regard to the direction of phase shift, so that any focal shift due to phase error is in the same direction for all patterns. In a preferred embodiment, the structurally identical inverted reticle is used to form an array of closely spaced contact or via openings. For a first pattern on the reticle, the feature will be the 0.degree. phase and the phase-shifting rim surrounding that feature will be the 180.degree. phase. All patterns surrounding the first pattern have phase-shifting rims of the 0.degree. phase and features of the 180.degree. phase. In this way, each pattern can form below conventional resolution features in the resist. Additionally, there will not be exposure of the regions between the closely spaced features since radiation transmitted through the closely spaced phase-shifting rims of the two patterns is 180.degree. out of phase. Also, since each pattern is structurally identical, any focal shift due to phase error is in the s…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.