Facile fabrication of high-resolution extreme ultraviolet interference lithography grating masks using footing strategy during electron beam writing

Abstract

The authors demonstrate a method for facile fabrication of transmission grating masks used in extreme ultraviolet interference lithography (EUV-IL) based on a footing strategy during electron beam writing of mask gratings. By modifying the electron beam lithography pattern and dose distribution, a thin footing is generated between the mask grating lines. This thin footing layer effectively prohibits subsequent metal deposition using a standard electroplating setup in the grating region, while outside the grating region metal is electrodeposited freely, absorbing EUV radiation and serving as an EUV-IL mask grating central photon stop layer. The strategy the authors present greatly simplifies the mask fabrication process and increases the yield, as the crucial central stop region can be fabricated directly and without further overlay exposure steps either using electron beam or photolithography.