Extreme ultraviolet interference lithography (EUV-IL) was employed to fabricate large area stamps with patterns of sub-50 nm half pitch for nanoimprint lithography (NIL). The resist patterns exposed by EUV-IL were transferred into underlying Si or SiO2/Si substratesby reactive ion etching. With this method, NIL stamps with feature sizes as small as 25 nm and patterned areas as large as 1 x 1 mm(2) were successfully produced. Using those stamps in NIL, the patterns with aspect ratio up to 2 were replicated with good replication fidelity. Increasing aspect ratio for the stamp patterns first results in distortion and discontinuity and then, the ripping of partial structures in the imprinted patterns. (C) 2004 American Vacuum Society.