|AVS 54th International Symposium|
|Plasma Science and Technology||Wednesday Sessions|
|Session:||Plasmas in Nanotechnology|
|Presenter:||T. Kubota, Tohoku Univ., Japan|
|Authors:||T. Hashimoto, Tohoku Univ., Japan
T. Kubota, Tohoku Univ., Japan
C.H. Huang, Tohoku Univ., Japan
M. Takeguchi, National Inst. for Mtls Sci., Japan
K. Nishioka, Japan Adv. Inst. of Sci. and Tech.
Y. Uraoka, Nara Inst. of Sci. and Tech., Japan
T. Fuyuki, Nara Inst. of Sci. and Tech., Japan
I. Yamashita, Matsushita Electric Industrial Co., Ltd, Japan
S. Samukawa, Tohoku Univ., Japan
|Correspondent:||Click to Email|
Nanometer-scale structures, such as quantum dots, are widely studied because of their possible application in the development of quantum-effect devices, such as quantum-dot lasers and single-electron transistors. To develop practical and robust quantum-effect devices, manufacturers must be able to fabricate selectively arranged, defect-free, sub-10-nm-scale structures of uniform size on substrates. To realize a nanometer-scale structure, we used a ferritin iron core (7 nm in diameter) as a uniform and high-density template and our developed neutral beam (NB) etching process for damage-free etching. We fabricated a "nanodisk,"a nanometer-thick disk-shaped silicon structure by patterning <3.5-nm poly-Si layer / 1.4-nm SiO2 layer / Si substrate> by using NB etching with a ferritin iron-core mask. To precisely control the diameter of the nanodisk, we must selectively remove the surface native silicon oxide layer before Cl neutral beam etching because the Cl neutral beam has extremely high selectivity to SiO2 film. SEM and TEM observations revealed that the nanodisk was successfully fabricated and that the buried SiO2 layer was not damaged during etching. When the nanodisk was only etched by using the Cl neutral beam with the iron core mask, the diameter of the nanodisk was about 13 nm. To shrink the diameter of nanodisk, we developed a dry process to remove native oxide by using NF3 gas and hydrogen radicals ("NF3 treatment"). By using the NF3 treatment to remove the native oxide, we decreased the nanodisk diameter to 10 nm. We found that removing the surface native oxide is very important for controlling the diameter of nanodisk. We then measured the I-V characteristics by using atomic force microscopy (AFM) with a conducting probe. Coulomb staircases were observed from the I-V measurements of the nanodisks at 25 K and at room temperature. These results indicate that the nanodisks we fabricated have a precise quantum-effect structure, and they attained single-electron properties. This research has great potential in the development of practical and robust fabrication processes for future quantum-effect devices. A part of this work was supported by the Nanotechnology Support Project and the Leading Project of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.