Invited Paper PS2+BI-ThA3
A New Approach to Nano-Fabrication of Functional Structures : Wet Nanotechnology and Bio Nano Process

Thursday, October 18, 2007, 2:40 pm, Room 607

We proposed a new method for the fabrication of functional nano-structures in an aqueous solution, which could be used in semiconductor processes or electron devices and can be called a wet nanotechnology (WNT). The WNT employs aqueous solutions as the environments for nano-blocks, which are thermally agitated, to self-organize into the functional nano-structures. The final structures could be designed in the initial nano-block structures and functional nanostructures can be produced economically. This is the same with the way how the lives are carrying out in the nature. So far, we invented several processes using the WNT and proteins, which collectively we named Bio Nano Process (BNP).¹ So far, the BNP produced several key components of the electron devices. Firstly, a floating nanodots gate memory (FNGM) was produced employing a cage-shaped protein, apoferritin (collaborative project with Dr. Fuyuki at NAIST). Nanoparticles (NP) were biomineralized in the apoferritin cavity, which produced homogenous NPs such as CdSe, ZnSe, CdS, Co3O4, InOx, Fe2O3 and so on. A 2D ordered array of the apoferritins with NP was made on the Si wafer by self-assembly and heat-treated The obtained 2D ordered array of NPs was applied for the FNGM.³ Secondly, we used 7nm Fe2O3 NPs, which were produced and placed on Si wafer by the BNP, as the nanometric etching mask to fabricate Si single crystal nanocolumn (a collaborative project with Dr. Samukawa at Tohoku Univ). The neutral beam etching successfully produced single crystal Si columns with 7nm diameter and high aspect ratio4. We further extended the BNP application and produced a large bio-template for single electron transistor (SET).⁵ A ball and spike type protein supramolecules which has a central cage-shaped protein and protruding spikes was produced by the self-assembly of genetically made chimera proteins. These experimental results demonstrated that the BNP can fabricate the inorganic nanostructure using protein supramolecules. The WNT and BNP are opening up a biological path to nano-electron devices.

¹I. Yamashita, Thin Solid Films, 393, 12-18 (2001)
²K. Iwahori et. al., Biological path of nanoparticles synthesis, Dekker Encyclopedia of Nanoscience and Nanotechnology, Taylar and Francis, 1 - 8 (2006)
³A. Miura et. al.,Jpn. J. Appl Phys, 45(1), L1-L3 (2006)
⁴T. Kubota, et. Al., Appl. Phys. Lett., 84(9), 1555-1557, 2004
⁵K. Sugimoto et. al., Angw. Chem. Int. Edi, 45(17), 2725-2728, 2006.