Patent ID: 6074786
Filing Date: 2000-06-13
Classification: G03F

Abstract:
A reticle for use in the manufacture of integrated circuits on a semiconductor workpiece adapted for inspection to determine the degree to which a reticle in a stepper is level by determining the degree of resolution at a plurality of sites on said semiconductor workpiece comprising:said reticle including a plurality of sets of alignment marks having an array of blocks which are in focus at different focal lengths,said reticle having a center,a set of said alignment marks located proximate to each of the corners of said reticle,a set of said alignment marks proximate to said center of said reticle, andsaid alignment marks including patterns which when in a best degree of focus provide a bright spot image in a microscope,said alignment marks being adapted for use in determining the pitch of said reticle at each position of the workpiece by obtaining measurements of the focal lengths at each of said alignment marks, andsaid alignment marks being adapted for checking leveling repeatedly to obtain information for producing optimum focus of the reticle image upon the region of the workpiece being exposed.