Fabrication of x-ray masks with 0.15-um level two-dimensional patterns by using highly accurate FIB lithography

A highly accurate focused ion beam (FIB) lithography and its application to the x-ray mask fabrication are discussed. The pattern delineation accuracy in FIB lithography was investigated by drawing various two-dimensional (2-D) test patterns. We could obtain 0.15 micrometers feature resist patterns on the heavy-metal layers of the x-ray mask substrate. FIB lithography suffers little proximity effect and thus various 2-D test patterns were obtained with small distortion. The FIB drawn patterns were precisely transferred into the W absorber layer by the time modulated etching technique. X-ray masks used for the evaluation of the pattern replication accuracy in synchrotron radiation lithography were successfully fabricated.