| AVS 56th International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS2+TF-WeM |
| Session: | Plasma Deposition and Plasma-assisted ALD |
| Presenter: | S. Iwashita, Kyushu University, Japan |
| Authors: | S. Iwashita, Kyushu University, Japan H. Miyata, Kyushu University, Japan H. Matsuzaki, Kyushu University, Japan K. Koga, Kyushu University, Japan M. Shiratani, Kyushu University, Japan |
| Correspondent: | Click to Email |
We have proposed a bottom-up nanosystem-fabrication method, which consists of production of nano-blocks and radicals (adhesives) in reactive plasmas, transport of nano-blocks towards a substrate, their arrangement on the substrate using pulse RF discharges with the amplitude modulation (AM) of the discharge voltage. For the method, control of the size of nano-blocks and their manipulation without their agglomeration are important. Up to now, we have succeeded in controlling the size of nano-blocks by pulse RF discharges,1 and have realized their rapid transport from their generation region towards a substrate with suppressing agglomeration by pulse RF discharges combined with AM.2,3 Here we report a criterion for driving nano-blocks rapidly and discuss their transport mechanisms.
Experiments were carried out using a capacitively coupled RF discharge reactor described elsewhere.1-3 Nano-blocks were formed in 13.56 MHz RF discharges of Si(CH3)2(OCH3)2 diluted with Ar. Nano-block transport in AM discharges is classified into two kinds: one is the rapid transport at a velocity more than 60 cm/s during the modulation period and the other is the slow transport at a velocity of 3-5 cm/s after turning off discharges due to temperature gradient. The key parameters to the rapid transport are the period Δt and voltage VAM of the modulation and asymmetry of the discharges, which is characterized by the dc self-bias voltage Vdc. The larger nano-blocks need longer Δt, higher VAM, and higher Vdc, for their rapid transport because of their large inertia. All nano-blocks of 26 nm in size, for instance, are transported rapidly during the modulation period for Vdc = -412 V, Δt = 100 ms and VAM = 1076 V, while 54 % of them transported rapidly during the modulation period and 46 % of them are transported after turning off discharges for Vdc = -350 V, Δt = 100 ms and VAM = 883 V. Just after the initiation of the modulation, electrostatic force drives nano-blocks, and then ion drag force drives them towards a substrate. It should be noted that although most nano-blocks are neutral, some of them turn into ones charged negatively due to charge fluctuation and such nano-blocks charged negatively are driven by electrostatic and ion drag forces. The method was applied to deposition of nano-block composite porous low-k films and dielectric films of k = 1.4 and Young’s modulus above 10 GPa were realized.
1S. Nunomura, M. Kita, K. Koga, M. Shiratani, and Y. Watanabe, J. Appl. Phys., 99, 083302 (2006).
2K. Koga, S. Iwashita, and M. Shiratani, J. Phys. D: Appl. Phys., 40, 2267 (2007).
3M. Shiratani, K. Koga, S. Iwashita, and S. Nunomura, Faraday Discuss., 137, 127 (2008).