title: Direct-Writing of Cu Nano-Patterns with an Electron Beam.
abstract: We demonstrate direct electron beam writing of a nano-scale Cu pattern on a surface with a thin aqueous layer of CuSO4 solution. Electron beams are highly maneuverable down to nano-scales. Aqueous solutions facilitate a plentiful metal ion supply for practical industrial applications, which may require continued reliable writing of sophisticated patterns. A thin aqueous layer on a surface helps to confine the writing on the surface. For this demonstration, liquid sample holder (K-kit) for transmission electron microscope (TEM) was employed to form a sealed space in a TEM. The aqueous CuSO4 solution inside the sample holder was allowed to partially dry until a uniform thin layer was left on the surface. The electron beam thus reduced Cu ions in the solution to form the desired patterns. Furthermore, the influence of e-beam exposure time and CuSO4(aq) concentration on the Cu reduction was studied in this work. Two growth stages of Cu were shown in the plot of Cu thickness versus e-beam exposure time. The measured Cu reduction rate was found to be proportional to the CuSO4(aq) concentration.
authors.affiliation: Department of Materials Science and Engineering,National Tsing-Hua University,Hsinchu 30013,Taiwan,R.O.C.
authors.forename: Shih-En
authors.initials: SE
authors.lastname: Lai
authors.affiliation: Department of Materials Science and Engineering,National Tsing-Hua University,Hsinchu 30013,Taiwan,R.O.C.
authors.forename: Ying-Jhan
authors.initials: YJ
authors.lastname: Hong
authors.affiliation: Department of Materials Science and Engineering,National Tsing-Hua University,Hsinchu 30013,Taiwan,R.O.C.
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Chen
authors.affiliation: Department of Materials Science and Engineering,National Tsing-Hua University,Hsinchu 30013,Taiwan,R.O.C.
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Kang
authors.affiliation: Department of Materials Science and Engineering,National Tsing-Hua University,Hsinchu 30013,Taiwan,R.O.C.
authors.forename: Pin
authors.initials: P
authors.lastname: Chang
authors.affiliation: Department of Materials Science and Engineering,National Tsing-Hua University,Hsinchu 30013,Taiwan,R.O.C.
authors.forename: Tri-Rung
authors.initials: TR
authors.lastname: Yew
keywords: Cu pattern; direct writing; electron beam-induced deposition; electron microscopy; liquid cell