Patent ID: 6856378

Claim:
A system for controlling exposure dose in a lithographic exposure tool for exposing a photoresist material applied to semiconductor wafers, and a reticle develops images in the photoresist material applied to the semiconductor wafers, and wherein the photoresist material is subject to batch changeover and the system operates with successive lot runs, including previous lot runs that were run prior in time and a current lot run that is currently being run, comprising: means for adjusting said exposure dose as a function of resist sensitivity changes, further comprising; a) means for calculating a batch factor that is an exposure dose ratio of current exposure dose performance to previous exposure dose performance by using historical data, comprising batch factors and optimum exposure doses from at least one previous lot run that was run prior in time to the current lot run; b) said means for adjusting said exposure dose comprises means for calculating a value of said exposure dose based on said calculated batch factor whereby said exposure dose in said lithographic exposure tool is controlled.