AVS 53rd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS1+BI-ThM

Paper PS1+BI-ThM8
Fabrication of High Density and High-Aspect Silicon Nano-column Using Neutral Beam Etching and Ferritin Iron Core Mask

Thursday, November 16, 2006, 10:20 am, Room 2009

Session: Plasmas in Bioscience
Presenter: S. Saito, Tohoku University, Japan
Authors: S. Saito, Tohoku University, Japan
T. Kubota, Tohoku University, Japan
T. Matsui, Matsushita Electric Industrial Co., Ltd., Japan
Y. Uraoka, Nara Institute of Science and Technology, Japan
T. Fuyuki, Nara Institute of Science and Technology, Japan
I. Yamashita, Matsushita Electric Industrial Co., Ltd. and Nara Institute of Science and Technology, Japan
S. Samukawa, Tohoku University, Japan
Correspondent: Click to Email
Semiconductor devices has been getting smaller and following Moore's Law. The design rule, the smallest line width, of these devices will be less than 50 nm nanometers within the next decade. Conventional optical lithography process has a theoretical limit to draw patterns smaller than the light wavelength and finer processing techniques are now being intensely surveyed but no methods meet the requests for mass nano-structure production. In order to breakthrough this limit, we have already proposed a new method to fabricate 7 nm nano-dots using the ferritin iron-core as an etching mask and Cl neutral beam for Si etching processes. The ferritin is one of the proteins and has a spherical protein shell with a cavity of 7 nm diameter. It can biomineralize iron as hydrated iron oxide in the cavity and store it in vivo. The Cl neutral beam could realize high etching anisotropy and high etching selectivity to ferritin iron-core without any radiation damages. In this study, we also tried to fabricate higher density and high-aspect Si nanocolumn structure using high-density array of ferritin iron core. The ferritin array could be made just over thin SiO@sub 2@ film (~3nm thick) on Si substrate. In this condition, however, the diameter of Si nanocolumn was enlarged to 14 nm and the etching profile had a slight taper because of extremely low SiO@sub 2@ etching rate using Cl neutral beam. To overcome the problem, we tried two-step neutral beam etching process. For quickly etching the surface SiO@sub 2@, F neutral beam was used. After that, the bulk Si was etched with high anisotropy using Cl neutral beam. As a result, for the first time, the diameter of Si nanocolumn could be shrunk with keeping highly anisotropic etching profile even at narrow space of less than 6nm. This study was supported by Leading Project of Ministry of Education, Culture, Sports, Science and Technology.