Method for fast estimation of lithographic binding patterns in an integrated circuit layout

Abstract

The present invention provides a lithographic difficulty metric that is a function of an energy ratio factor that includes a ratio of hard-to-print energy to easy-to-print energy of the diffraction orders along an angular coordinate [theta]i of spatial frequency space, an energy entropy factor comprising energy entropy of said diffraction orders along said angular coordinate [theta]i, a phase entropy factor comprising phase entropy of said diffraction orders along said angular coordinate 6,, and a total energy entropy factor comprising total energy entropy of said diffraction orders (430, 440).; The hard-to-print energy includes energy of the diffraction orders at values of the normalized radial coordinates r of spatial frequency space in a neighborhood of r=0 and in a neighborhood of r=l, and the easy-to-print energy includes energy of the diffraction orders located at intermediate values of normalized radial coordinates r between the neighborhood of r=0 and the neighborhood of r=l. The value of the lithographic difficulty metric may be used to identify patterns in a design layout that are binding patterns in an optimization computation. The lithographic difficulty metric may be used to design integrated circuits that have good, relatively easy-to-print characteristics.

Description

technical field [0001] The present invention relates broadly to lithographic printing of features for patterning integrated circuits (ICs) on semiconductor chips, and in particular to improvements in the selection and use of illumination source characteristics in combination with diffractive shapes on reticle masks , and more particularly relates to improvements in identifying and prioritizing IC design portions where optimization of lithography processes is performed more economically. Background technique [0002] Photolithographic processes are commonly used in the manufacture of integrated circuits in which radiation is projected through a patterned mask to pattern a wafer to form an image on a light-sensitive material called photoresist or simply resist pattern. The exposed resist material is developed to form openings corresponding to the image pattern, and the pattern is then transferred to the wafer substrate by methods as known in the art, such as etching. [0003...

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