Method of fabricating phase shifting reticles with an accurate phase shift layer
US5194346A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 15, 1991 |
| Grant date | Mar 16, 1993 |
| Priority date | — |
| Expiry date | Apr 15, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/30
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method of fabricating phase shifting reticles that can be used as a mask in photolithographic processes such as semiconductor wafer patterning. An opaque film such as chromium is first deposited on a transparent substrate. The opaque film is then patterned with openings by a first photolithographic process. A phase shifter material such as (SiO.sub.2) is then blanket deposited into the openings and over the opaque film. The phase shifter material is then polished by chemical mechanical planarization (CMP) to a thickness "T" which is selected to produce a 180.degree. phase shift. The phase shifter material is then photopatterned and selectively etched by a second photolithographic process to remove all of the phase shifter material except in every other opening formed in the opaque film. This forms a repetitive pattern of alternating phase shifters and light transmission openings through the opaque film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.