Determination of the critical dimension and proximity bias variations across the lens field by electrical linewidth measurements

Electrical critical dimension (CD) measurements are now widely used as a ch aracterization technique in optical lithography. In this paper this techniq ue is applied to the determination of the CD and proximity bias variations across the lens field. A method, based on statistical considerations, is in troduced to decorrelate the contribution of the mask to the global Across F ield linewidth variation (AFLV). It is shown that the mask CD dispersion ha s an important contribution in the total CD range observed on the wafer. By using this technique, a lens quality determination has been done and the o ptical contribution to the field CD dispersion has been determined. Moreove r, because it is a fast and accurate technique, we show that electrical lin ewidth measurements can be used in a lens characterization procedure. Resul ts obtained indicate that the proximity bias dispersion across the lens fie ld is not negligible and the question of a dependent field position correct ion is raising up.