Exact transmission balanced alternating phase-shifting mask for photolithography
US5932377A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 24, 1998 |
| Grant date | Aug 3, 1999 |
| Priority date | — |
| Expiry date | Feb 24, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/30
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A two-step method for eliminating transmission errors in alternating phase-shifting masks is described. Initially, the design data is selectively biased to provide a coarse reduction in the inherent transmission error between features of different phase, size, shape, and/or location. During fabrication of the mask with the modified data, residual transmission errors are then eliminated via the positioning of the edges of the etched-quartz trenches which define the phase of a given feature to a set location beneath the opaque chrome film. Application of feedback, in which the aerial image of the mask is monitored during the positioning of the etched-quartz edges, provides additional and precise control of the residual transmission error.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.