Half tone phase shift masks with staircase regions and methods of fabricating the same

摘要

A phase shift mask includes a phase shift region and an unshifted phase region in spaced apart relation on a phase shift mask substrate, and a half tone region on the unshifted phase region. The half tone region changes the phase of radiation incident thereon. The half tone region preferably defines a staircase region which causes destructive interference of incident radiation which can thereby reduce the critical distance difference between patterns formed with the phase shift region and the unshifted phase region. The phase shift mask may be fabricated by forming a phase shift layer on a phase shift mask substrate and forming a patterned chrome layer on the phase shift layer which exposes a first portion and a second portion of the phase shift layer. A phase shift region is formed in the first portion of the phase shift layer and a half tone region and an unshifted phase region are formed in the second portion of the phase shift layer.