title: Low-voltage-exposure-enabled hydrogen silsesquioxane bilayer-like process for three-dimensional nanofabrication.
abstract: We report a bilayer-like electron-beam lithographic process to obtain three-dimensional (3D) nanostructures by using only a single hydrogen silsesquioxane (HSQ) resist layer. The process utilizes the short penetration depth of low-energy (1.5 keV) electron irradiation to first obtain a partially cross-linked HSQ top layer and then uses a high-voltage electron beam (30 keV) to obtain self-aligned undercut (e.g. mushroom-shaped) and freestanding HSQ nanostructures. Based on the well-defined 3D resist patterns, 3D metallic nanostructures were directly fabricated with high fidelity by just depositing a metallic layer. As an example, Ag-coated mushroom-shaped nanostructures were fabricated, which showed lower plasmon resonance damping compared to their planar counterparts. In addition, the undercut 3D nanostructures also enable more reliable lift-off in comparison with the planar nanostructures, with which high-quality silver nanohole arrays were fabricated which show distinct and extraordinary optical transmission in the visible range.
authors.affiliation: School of Physics and Electronics, State Key Laboratory for Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, People's Republic of China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Xiang
authors.forename: Yiqin
authors.initials: Y
authors.lastname: Chen
authors.forename: Yasi
authors.initials: Y
authors.lastname: Wang
authors.forename: Mengjie
authors.initials: M
authors.lastname: Zheng
authors.forename: Zhiqin
authors.initials: Z
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Peng
authors.forename: Yanming
authors.initials: Y
authors.lastname: Zhou
authors.forename: Bo
authors.initials: B
authors.lastname: Feng
authors.forename: Yifang
authors.initials: Y
authors.lastname: Chen
authors.forename: Huigao
authors.initials: H
authors.lastname: Duan