Resolution enhancing technology using phase assignment bridges

Abstract

In one embodiment, a spacing is determined for each edge of a number of features in a photolithographic design. The edges have at least a partially predictable layout. Based on the spacing and the predictable layout, a bridge structure is generated. Each bridge of the bridge structure connects one of the edges to an edge of a neighboring feature. Then, the features and the bridge structure are provided for a phase assignment. The phase assignment assigns features at opposite ends of each bridge in the bridge structure to opposite phases. In another embodiment, a sub-resolution assist feature (SRAF) is introduced for an edge of a feature and a bridge is generated from the feature to the SRAF. Then, the feature and the SRAF are assigned to opposite phases based on the relationship defined by the bridge.

Description

FIELD OF THE INVENTION [0001] The present invention pertains to the field of Resolution Enhancing Technologies (RET) in photolithography. More particularly, this invention relates to generating bridges between features and using the bridges to assign the features to particular phases. BACKGROUND OF THE INVENTION [0002] In photolithography, a design is transferred onto a surface by shining a light through a mask of the design onto a photosensitive material covering the surface. The light exposes the photo-sensitive material in the pattern of the mask. A chemical process etches away either the exposed material or the unexposed material, depending on the particular process that is being used. Another chemical process etches into the surface wherever the photosensitive material was removed. The result is the design itself, either imprinted into the surface where the surface has been etched away, or protruding slightly from the surface as a result of the surrounding material having been ...

AI Technical Summary

Problems solved by technology

Market pressures, however, continually drive for smaller components, higher density, and greater functionality.

For instance, the ends of lines are cut off, sharp corners are rounded, and features become increasingly interdependent, causing features “bleed” into each other or not resolve at all.

PSM, however, is not usually applied to large areas or entire design layers because, in the complex areas where PSM is usually needed, it is often very difficult to assign phases.

In these complex situations, there usually is no clear, predictable approach to phase assignment, making PSM difficult, time consuming, and costly to apply.

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