Title: Attempts to form the 10-nm-order pitch of self-assembled nanodots using PS-PDMS block copolymer

Authors: Miftakhul Huda; Jing Liu; Zulfakri Bin Mohamad; You Yin; Sumio Hosaka

Addresses: Graduate School of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu, 376-8515, Japan ' Graduate School of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu, 376-8515, Japan ' Advanced Technology Research Center, Gunma University, 1-5-1 Tenjin-cho, Kiryu, 376-8515, Japan ' Division of Electronics and Informatics, Gunma University, 1-5-1 Tenjin-cho, Kiryu, 376-8515, Japan ' Division of Electronics and Informatics, Gunma University, 1-5-1 Tenjin-cho, Kiryu, 376-8515, Japan

Abstract: Block copolymer (BCP) self-assembly exhibits its ability to form various nanostructures with a size down to 3 nm, which is particularly attractive for emerging technologies such as bit patterned media (BPM). Poly(styrene-b-dimethyl siloxane) (PS-PDMS) has been acknowledged as the most promising block copolymer for self-assembly fabrication due to its possibility to form nanopattern with a fine pitch, high etching selectivity, and its characteristic of robustness for pattern transfer. Here, we attempt to form PS-PDMS self-assembled nanodot array with a 10-nm-order pitch in order to satisfy the demand of low cost technique to form ultrahigh density nanodot array for BPM, which is regarded as the next-generation magnetic recording media, and for quantum devices such as the third-generation quantum dot photovoltaic cell and future battery cell. In this study, self-assembled nanodot array on a large area with pitches of 11 nm (σ = 2.08 nm) and 10 nm (σ = 1.61 nm) was formed using PS-PDMS with molecular weights of 5600-1300 g/mol (minority block volume fraction fPDMS = 19.8%) and 4700-1200 g/mol (fPDMS = 21.4%), respectively. In experiments, it was shown that some critical parameters, such as the thickness of PS-PDMS film, the treatment of the substrate surface, and annealing condition, played crucial roles in forming 10-nm-order size of self-assembled nanodot array using PS-PDMS. The relationships between pitches of PS-PDMS nanodot array and the product of the total number of segments and the Flory-Huggins segmental interaction parameter (χN) obtained by calculations and experiments will be discussed. Based on the position of PS-PDMS on mean-field phase diagram for BCP melts, the possibility to form nanodot array with a pitch of less than 10 nm is described. This study promises to open way toward the fabrication of more than 7.45 Tbit/in.² storage devices and the application of quantum devices.

Keywords: nanolithography; self-assembly; block copolymers; nanodots; bit patterned media; BPM; magnetic storage; nanotechnology; nanopatterns; magnetic recording media; quantum devices; PV cells; photovoltaic cells; battery cells.

DOI: 10.1504/IJNT.2014.060561

International Journal of Nanotechnology, 2014 Vol.11 No.5/6/7/8, pp.425 - 433

Published online: 14 Apr 2014 *

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