Fabrication of ultrahigh resolution metal nanowires and nanodots through EUV interference lithography

We demonstrate the fabrication of high-resolution (sub-100 nm) nanowires and nanodots using HSQ/PMMA bilayer resists for a negative-tone lift-off process. The high resolution patterning on HSQ layers was performed using EUV (extreme ultraviolet) interference lithography at the Swiss Light Source (SLS). The thicknesses of HSQ and of the sacrificial PMMA layers were optimized for different resolutions. We succeeded in transferring periodic HSQ nanoline structures with resolution as high as 16 nm half-pitch into PMMA layers by O-2 plasma etching and then into Cr/Au nanowires by metallization and lift-off. The duty cycles of the nanowires are varied by controlling the exposure doses of the irradiation light. HSQ nanodots and nanoholes are obtained by exposing the resist layer using a two-dimensional mask. After subsequent treatment, Cr/Au nanodots with sizes of 25 nm-60 nm are obtained. (C) 2015 Elsevier B.V. All rights reserved.