Martin Feldman, Alan David White: Zone plate alignment marks. Bell Telephone Laboratories Incorporated, Lucian C Canepa, July 26, 1977: US04037969 (82 worldwide citation)

Certain classes of patterns, for example so-called zone plates, are utilized as alignment marks in the fabrication of integrated circuits. Such a plate, which functions as a lens, provides a high-brightness image that is relatively insensitive to any degradation of the pattern.

Martin Feldman, Alan D White, Donald L White: Wafer tilt compensation in zone plate alignment system. Bell Telephone Laboratories Incorporated, Lucian C Canepa, Arthur J Torsiglieri, August 16, 1983: US04398824 (25 worldwide citation)

The present invention is a method and apparatus for aligning a semiconductor wafer to be patterned by a step-and-repeat photolithographic system. The inventive alignment technique, which is able to compensate for local wafer tilt and/or nonuniform photoresist thickness, is applicable to semiconducto ...