Nano Patterning on Surfaces of 3-D Micro Structures by Means of Block Copolymer Self Assembly
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Nano Patterning on Surfaces of 3-D Micro Structures by Means of Block Copolymer Self Assembly Shin’ichi Warisawa1 , Hiroyuki Mino1, Reo Kometani1 and Sunao Ishihara1 1 Department of Mechanical Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8656, Japan ABSTRACT In this paper, we present the possibility of nano-scale patterning on surfaces of 3-D micro structures by means of block copolymer self assembly. We succeeded in forming vertical cylinders on the surfaces of the 3-D micro structures using dip-coat process with Au deposition instead of random copolymers. The material of 3-D structures fabricated by FIB-CVD was diamond-like carbon (DLC) due to selecting phenanthrene as a gas source. Since the surface energy of DLC is low, instead of PS-r-PMMA polymer brush, 100 nm-thick Au films were coated on the surfaces of 3-D structures. PS-b-PMMA (PS:PMMA = 50 kg/mol:21 kg/mol) was dip-coated on the Au coated surfaces and annealed. First, we prepared DLC 60° angled slope with size of 2.5 by 3 μm2. As a result, the vertical cylinders were formed in a similar way regardless of the places, i.e., top, middle and bottom on the slopes. vertical cylinders were formed regularly and densely on the entire slope. In order to investigate the effect of slope angle, we prepared 3-D micro structures with different angled slopes such as 70, 80 and 90°. There was no slope angle specific difference, and vertical cylinders were also formed on each slope. INTRODUCTION Recently, three-dimensional (3-D) nano- and microstructures have been of great interest to realize innovative devices. However, such 3-D structures require very complicated and timeconsuming processes for fabrication if based on semiconductor fabrication techniques. Focused ion beam etching and deposition techniques enable to fabricate complicated 3-D structures[1]. Such structures will need electric wiring with them to be actuated and smaller functional devices on them to sense something. Recent block copolymer self-assembly researches have demonstrated the potential to form aligned line patterns[2], periodical sphere structures, and directed line and sphere patterns using chemical and physical templates at nano scale[3]. Many of these have been examined mainly on 2-D flat substrates. Ordered nano structures of block copolymer film are of great interest for lithographic applications such as patterned media, quantum dots and so on[4, 5]. For alignment control purpose, as well as chemically patterned substrates, topographic patterns such as groove[6], honeycomb, step-like[7], pillar array structures[8] have been investigated. Even in those cases, self-assembled copolymer structures are discussed from 2-D viewpoint. Enhancing the potential of nano patterning onto 3-D structures may extend further applications such as wiring for electro circuits on nano- and micro-electro mechanical systems, and 3-D structured optical devices and high-density memory devices. In this research, we demonstrate the possibility of nano-scale patterning on th
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