Structure and method for fixing phase effects on EUV mask

摘要

This invention relates to a structure for fixing phase effects on EUV mask which contains a repeating pattern with an assist feature, or a pattern with two different sized features in close proximity. The EUV mask with the repeating pattern is capable of printing a group of trenches on a photoresist layer. The invention also relates to a method of fabricating an EUV mask for fixing phase effects. The EUV mask contains an absorber layer over the multilayer reflector, and the absorber layer is patterned to form a mask pattern which contains absorptive regions and reflective regions. The absorber is in the absorptive regions, and a phase shifter is deposited at least in the whole reflective regions of the mask pattern to a thickness capable of correcting phase effects. The phase shifter has an index of refraction value is about equal to or less than that of the absorber. The thickness of the phase shifter is determined by simulation.

主权项

1. An EUV mask for fixing phase effects comprising:
a mask substrate; a multilayer reflector having a plurality of layers on the mask substrate, each layer having a thickness less than about 10 nm; a mask pattern over the multilayer reflector, the mask pattern comprises absorptive regions and reflective regions, wherein the absorptive regions comprise an absorber having a thickness less than about 150 nm and the reflective regions comprise openings created inside the mask pattern, a first set of the openings having a width of equal to or less than about 60 nm; and a phase shifter over the multilayer reflector, the phase shifter deposited inside the openings in all the reflective regions of the mask pattern to a thickness less than the thickness of the absorber, said thickness of the phase shifter capable of, during an EUV exposure process, correcting phase effects caused by a phase shift present on a mask.