Shape metrology for photomasks

摘要

A method of manufacturing a photomask includes forming a mask pattern with a critical mask feature on a photomask. Shape information which is descriptive for an outline of the critical mask feature is obtained from the photomask. The shape information contains position information identifying the positions of landmarks on the outline relative to each other. The landmarks may indicate local curvature extrema, points of inflexion, sharp bends in the curvature and/or local curvature-change maxima in the outline of the mask feature, respectively. The shape information may enable a shape metrology which is not completely based on rectangular approximations of mask features.

主权项

1. A method of manufacturing a photomask, the method comprising:
forming a mask pattern including a critical mask feature on a photomask; and scanning or imaging the photomask to optically retrieve, from the photomask, shape information descriptive for an outline of the critical mask feature on the photomask, wherein the shape information contains position information identifying the positions of isolated landmarks on the outline relative to each other and wherein first ones of the landmarks indicate at least one of local curvature extrema, points of inflexion, sharp bends in the curvature and local curvature-change maxima in the outline of the critical mask feature, respectively.