Method and apparatus for the determination of mask rules using scatterometry

Abstract

A method and apparatus for determining optical mask corrections for photolithography. A plurality of grating patterns is printed onto a wafer utilizing a photomask having at least one grating. Each grating pattern within the plurality of grating patterns is associated with known photolithographic settings. Each grating pattern is illuminated independently with a light source, so that light is diffracted off each grating pattern. The diffracted light is measured utilizing scatterometry techniques to determine measured diffracted values. The measured diffracted values are compared to values in a library to determine a profile match. A 2-dimensional profile description is assigned to each grating pattern based on the profile match. A database is compiled of the profile descriptions for the plurality of grating patterns. Photomask design rules are then generated by accessing the database containing the 2-dimensional profile descriptions. In preferred embodiments, the design rules are used to create and correct masks containing OPC corrections, phase-shifting mask corrections and binary masks. In a preferred embodiment the at least one grating is a bi-periodic grating. In a preferred embodiment, the scatterometry technique is optical digital profilometry utilizing a reflectometer or ellipsometer.