Nanopatterning of Au absorber films on Mo/Si EUV multilayer mirrors by STMlithography in self-assembled monolayers

We report on the fabrication and characterization of artificial nanostructu res in alkanethiol-type self-assembled monolayers (SAMs) and subsequent pat tern transfer into the underlying Au film by wet etching. A gold-covered Mo /Si multilayer was immersed in a solution of hexadecanthiol molecules [CH3( CH2)(15)SH], thus forming a self-assembled monolayer spontaneously on top o f the Au surface. Afterwards, the SAM films were patterned by STM lithograp hy in ultra-high-vacuum ambient with 1 V bias voltage and 1 nA tunnel curre nt. The patterns were transferred, by a wet etching process using a solutio n of 0.1 M KCN and 1 M KOH, into the underlying gold layer followed by a ch aracterization by means of atomic force microscopy and scanning electron mi croscopy. The patterned Au films act as an efficient EUV absorber layer on top of the underlying EUV multilayer mirror, thus providing an amplitude-mo dulated EUV multilayer structure. (C) 2000 Elsevier Science B.V. All rights reserved.