| US 7,550,235 B2 | ||
| Method and apparatus for performing model based placement of phase-balanced scattering bars for sub-wavelength optical lithography | ||
| Xuelong Shi, San Jose, Calif. (US); Jang Fung Chen, Cupertino, Calif. (US); Thomas Laidig, Point Richmond, Calif. (US); Kurt E. Wampler, Sunnyvale, Calif. (US); and Douglas Van Den Broeke, Sunnyvale, Calif. (US) | ||
| Assigned to ASML Masktools B.V., Ah Veldhoven (Netherlands) | ||
| Filed on Sep. 03, 2004, as Appl. No. 10/933,496. | ||
| Claims priority of provisional application 60/500260, filed on Sep. 05, 2003. | ||
| Prior Publication US 2005/0142449 A1, Jun. 30, 2005 | ||
| Int. Cl. G03F 1/02 (2006.01) | ||
| U.S. Cl. 430—5 [716/19; 716/21; 382/144] | 12 Claims |
| 1. A method of generating a mask design having optical proximity correction features disposed therein, said method comprising
the steps of:
obtaining a target pattern having features to be imaged on a substrate;
generating a first interference map based on said target pattern, said first interference map defining areas of constructive
interference between at least one of said features to be imaged and a field area adjacent said at least one feature;
placing a first set of assist features having a first phase in the mask design based on the areas of constructive interference
defined by said first interference map;
generating a second interference map based on said first set of assist features, said second interference map defining areas
of constructive interference between assist features of said first set of assist features and a field area adjacent at least
one of said assist features of said first set of assist features; and
placing a second set of assist features having a second phase in the mask design based on the areas of constructive interference
defined by the second interference map, wherein said first phase does not equal said second phase.
|