Variations are characterized in feature dimensions of an integrated
circuit that is to be fabricated in accordance with a design by a process
that produces topographical variation in the integrated circuit, the
variations in feature dimension being caused by the topographical
variations. The process includes lithography or etch. Predicted
characteristics are verified to conform to the design, the
characteristics including feature dimensions or electrical
characteristics. A process is selected for use in fabricating the
integrated circuit based on the relative predicted variations. Chip-level
features of a design of an integrated circuit are verified for
manufacture within focus limitations of a lithographic tool. Whether a
design of a level of an integrated circuit can be lithographically imaged
in accordance with the design is predicted, and if it cannot be, the
design or processing parameters are adjusted so that it can be.