We present a method for repairing defects near the top surfaces of multilayer coatings in general and specifically on extreme-ultraviolet lithography mask blanks. Milling away the defect and a surrounding region of the multilayer by use of a focused ion beam can repair both the reflectivity and the phase of the reflected light in the vicinity of such a defect. We describe the conditions under which the repaired region will not itself be a defect and experimentally demonstrate the feasibility of this multilayer repair technique. The results described are also applicable to understanding and controlling the optical effects of ion-induced multilayer erosion.
© 2004 Optical Society of America
(110.3960) Imaging systems : Microlithography
(110.5220) Imaging systems : Photolithography
(160.4670) Materials : Optical materials
(220.3740) Optical design and fabrication : Lithography
(230.4170) Optical devices : Multilayers
Anton Barty, Stefan Hau-Riege, Dan Stearns, Miles Clift, Paul Mirkarimi, Eric Gullikson, Henry Chapman, and Don Sweeney, "Repairing Amplitude Defects in Multilayer-Coated Extreme-Ultraviolet Lithography Reticles by Use of a Focused Ion Beam," Appl. Opt. 43, 6545-6556 (2004)