US Patent 7732109 Method and system for improving critical dimension uniformity

A method for improving critical dimension uniformity of a wafer includes exposing a plurality of mask patterns on a first plurality of substrates at predetermined locations with common splits conditions of focus and exposure dose for each of the first plurality of substrates to form a plurality of perturbed wafers; measuring a critical dimension of the plurality of mask patterns at each of the predetermined locations for each of the plurality of perturbed wafers; averaging the critical dimension measured at each of the predetermined locations over the plurality of perturbed wafers to form a perturbed critical dimension map; measuring a sidewall angle of the plurality of mask patterns; averaging the sidewall angle measured to form a perturbed sidewall angle map; and providing the perturbed critical dimension map and the perturbed sidewall angle map to an exposure tool.