Full-chip hierarchical inverse lithography

A computer readable storage medium comprising instructions recorded thereon, the instructions, when executed by a computer, cause the computer to perform a method of obtaining a mask pattern for printing a target pattern using an optical system, the method comprising:

• identifying a model of the optical system;
• generating the mask pattern from the target pattern using the model;
• and
• enforcing symmetry during the generating of the mask pattern such that the generated mask pattern has the same symmetry with respect to an illumination source associated with the optical system,
• wherein generating the mask pattern includes generating a grayscale map corresponding to the target pattern, wherein enforcing symmetry includes causing the generated grayscale map to be symmetric regardless of the position and orientation of the target pattern;
• and
• preparing a file having a format associated with a mask in accordance with the generated mask pattern, wherein the mask is configured to be placed in the optical system.

A system for obtaining a mask pattern for printing a target pattern using an optical system, comprising:

• a map computation module that is adapted to generate a map from the target pattern using a model of the optical system, wherein the map computation module is further adapted to enforce symmetry during the generating of the map such that the generated map has the same symmetry with respect to an illumination source associated with the optical system, and wherein enforcing symmetry includes causing the generated map to be symmetric regardless of the position and orientation of the target pattern, wherein the target pattern includes a plurality of target polygons, and wherein the map computation module is further adapted to generate first grayscale maps for each of the target polygons and combine the first grayscale maps together to obtain the map corresponding to the target pattern;
• and
• a polygon module that is adapted to use the map to form polygons so as to generate the mask pattern, the polygon module being adapted to enforce symmetry during the generating of the mask pattern such that the generated mask pattern has the same symmetry with respect to the illumination source associated with the optical system,
• wherein the system is further configured to prepare a file having a format associated with a mask in accordance with the generated mask pattern, wherein the mask is configured to be placed in the optical system.