Gradated photomask and its fabrication process
US8124301B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 19, 2006 |
| Grant date | Feb 28, 2012 |
| Priority date | — |
| Expiry date | Nov 12, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/50
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention provides a gradated photomask for reducing photolithography steps and its fabrication process, which make use of a generally available photomask blank, prevents the reflectance of a light shield film from growing high, makes alignment easy during the formation of a semitransparent film, and enables the semi-transparent film on a light shield pattern with good step coverage. A photomask (100) comprises a mixture of a light shield area including a light shield film (114) having a desired pattern on a transparent substrate wherein a film forming the pattern is substantially opaque to photolithographic light, a semitransparent film (113) that transmits the photolithographic light at a desired transmittance, and the light shield film (114) and the semitransparent film (113) are stacked on the transparent substrate (101) in that order; a semi-transparent area wherein there is only the semitransparent film (113); and a transmissive area there is neither the light shield film (114) nor the semitransparent film (113), and is characterized in that the semitransparent film (113) has an antireflection function with respect to the photolithographic light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.