The registration difficulty associated with a resist‐coated alignment mark depends on the
type of optics used to illuminate and view the wafer alignment aid. The interaction of the light
with the mark geometry is studied by calculating the outgoing wave front that results when
an arbitrary collection of correlated or uncorrelated incident wave fronts is reflected from the
nonplanar target structure. This solution is combined with a model of the partially coherent
imaging system to predict the alignment signal. Bright‐field and dark‐field systems typical of …