Cell library that can automatically avoid forbidden pitches

Abstract

Resolution enhancement techniques (RETs) aid in accurately transferring features on a layout to a wafer. Unfortunately, RETs may work well at one pitch but not another pitch. If image quality falls below an acceptable threshold at a certain pitch, then such a pitch is called a forbidden pitch. A cell library cell that can automatically avoid forbidden pitches is provided. In this method, evaluation points on edges of a feature in a cell can be analyzed based on a RET and a lithography model. Using this analysis, any forbidden pitch for the feature can be identified. Additionally, any forbidden pitch can be changed to an acceptable pitch, i.e. a pitch resulting in an acceptable image quality. The forbidden pitch information and the associated acceptable pitch information for the feature can be stored in a database to facilitate analyzing other features/cells.