title: Wafer Scale Fabrication of Dense and High Aspect Ratio Sub-50 nm Nanopillars from Phase Separation of Cross-Linkable Polysiloxane/Polystyrene Blend.
abstract: We demonstrated a simple and effective approach to fabricate dense and high aspect ratio sub-50 nm pillars based on phase separation of a polymer blend composed of a cross-linkable polysiloxane and polystyrene (PS). In order to obtain the phase-separated domains with nanoscale size, a liquid prepolymer of cross-linkable polysiloxane was employed as one moiety for increasing the miscibility of the polymer blend. After phase separation via spin-coating, the dispersed domains of liquid polysiloxane with sub-50 nm size could be solidified by UV exposure. The solidified polysiloxane domains took the role of etching mask for formation of high aspect ratio nanopillars by O2reactive ion etching (RIE). The aspect ratio of the nanopillars could be further amplified by introduction of a polymer transfer layer underneath the polymer blend film. The effects of spin speeds, the weight ratio of the polysiloxane/PS blend, and the concentration of polysiloxane/PS blend in toluene on the characters of the nanopillars were investigated. The gold-coated nanopillar arrays exhibited a high Raman scattering enhancement factor in the range of 108-109with high uniformity across over the wafer scale sample. A superhydrophobic surface could be realized by coating a self-assembled monolayers (SAM) of fluoroalkyltrichlorosilane on the nanopillar arrays. Sub-50 nm silicon nanowires (SiNWs) with high aspect ratio of about 1000 were achieved by using the nanopillars as etching mask through a metal-assisted chemical etching process. They showed an ultralow reflectance of approximately 0.1% for wavelengths ranging from 200 to 800 nm.
authors.affiliation: Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Yang
authors.identifier: http://orcid.org/0000-0001-6017-094X
authors.initials: Y
authors.lastname: Li
authors.affiliation: Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Yuli
authors.initials: Y
authors.lastname: Hao
authors.affiliation: Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Chunyu
authors.initials: C
authors.lastname: Huang
authors.affiliation: Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Xingyao
authors.initials: X
authors.lastname: Chen
authors.affiliation: Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Chen
authors.affiliation: Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Yushuang
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Changsheng
authors.initials: C
authors.lastname: Yuan
authors.affiliation: Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Qiu
authors.affiliation: Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Haixiong
authors.initials: H
authors.lastname: Ge
authors.affiliation: Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Chen
keywords: antireflective film; dense and high aspect ratio nanopillars; phase separation; superhydrophobic surface; surface-enhanced Raman scattering