Patent ID: 6417929
Filing Date: 2002-07-09
Classification: G01B,G03F

Abstract:
A system for optically measuring lithographic process bias of a minimum feature formed by a lithographic process, the system comprising:a pattern adapted to create an array of elements by the lithographic process on a substrate, the elements having spaces therebetween, each element in the array having a nominal length and a nominal width and each space having a nominal width, the nominal width of each element and of each space corresponding to the minimum feature and the nominal length being larger than the minimum feature; an actual array of elements created by the lithographic process on the substrate, each element having an actual length and an actual width and each space having an actual width; a darkfield imaging system adapted to create a darkfield image of the actual array of elements; an optical detector for detecting the darkfield image and for producing corresponding electronic information therefrom; and a signal processor for processing the electronic information to determine the lithographic process bias corresponding to a difference between the actual width and the nominal width as calculated based on a difference between the actual length and the nominal length.