23G03
Self-organized carbon mask formation on the top surface of fine trenches
using a low temperature plasma anisotropic CVD
for depositing fine organic structure
低温プラズマ異方性CVDを用いた微細トレンチ上面への自己組織カーボンマスク形成
Kazunori Koga1), Tatsuya Urakawa1), Giichiro Uchida1), Hyunwoong Seo1), Kunihiro Kamataki2),
Naho Itagaki1,5), Masaharu Shiratani1,6), Yuichi Setsuhara3,6), Makoto Sekine4,6), and Masaru Hori4,6)
古閑一憲1), 浦川達也1)，内田儀一郎1)，徐 鉉雄1)，鎌瀧晋礼2),
板垣奈穂1,5)，白谷正治1,6)，節原裕一3,6)，関根 誠4,6)，堀 勝4,6)1)

Graduate School of Information Science and Electrical Engineering, Kyushu University744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
2)
Center for Research and Advancement in High Education, Kyushu University, Fukuoka 819-0395, Japan
3)
Joining and Welding Research Institute, Osaka University, Osaka 567-0047, Japan
4)
Department of Electrical Engineering and Computer Science, Nagoya University, Nagoya 464-8603, Japan
5)
PRESTO, Japan Science and Technology Agency, Tokyo 102-0075, Japan
6)
CREST, Japan Science and Technology Agency, Tokyo 102-0075, Japan1)
九州大学大学院システム情報科学府 〒819-0395 福岡県福岡市西区元岡744番地
2)
九州大学高等教育開発推進センター 〒819-0395 福岡県福岡市西区元岡744番地
3)
大阪大学接合科学研究所 〒567-0047 大阪府茨木市美穂ヶ丘11-14)
名古屋大学大学院工学研究科 〒464-8603 愛知県名古屋市千種区不老町5)
JST CREST 〒102-0075 東京都千代田区三番町56)
JST さきがけ 〒102-0075 東京都千代田区三番町5
We have realized deposition of carbon masks on the top surface of trenched substrates using ahydrogen(H)-assisted plasma chemical vapor deposition (CVD). Deposition rate is determined by thebalance between deposition rate of carbon containig radicals and etching rate by H atoms. Ion irradiation
brings about the higher hardness of films and hence the lower etching rate. A high H atom flux is the key todeposition only on the top surfasse of trenched substrates.

1. Introduction
Diamond like carbon (DLC) and amorphous
carbon films have widespread applications asprotective coatings in several areas such as
biomedical coatings and micro-electromechanicalsystems (MEMS) due to their biocompatibility,
chemical inertness, high mechanical hardness,
optical transparency, and wide band gap. Deposition
profile of DLC and amorphous carbon films intrenches is one of the concerns to realize coatings
on patterned substrates. Low temperaturedeposition below 100oC is important to realize
deposition on polymer substrates. We havesucceeded in controlling deposition profile ofplasma CVD carbon films in trenches and haverealized sub-conformal, conformal and anisotropic
deposition, for which carbon is filled preferentiallyfrom the bottom of trenches without sidewall
deposition using a H-assisted plasma CVD method[1, 2]. In this study, we have examined effects of H

atoms on deposition profiles and have realized anovel deposition profile, for which carbon films aredeposited on the top of trenches without depositingon the bottom and sidewall, at a low substratetemperature of 100oC. Here, we report theseexperimental results.
2. Experimental setup
Experiments were performed using theH-assisted plasma CVD reactor, in which a
capacitively-coupled main discharge and an
inductive-coupled discharge for an H atom source
were sustained. This reactor provided independent
control of generation rates of carbon-related
radicals as deposition precursors and H atoms asetching precursors. An rf bias voltage of 400 kHz
was applied to a substrate for controlling kinetic
energy of ions impinging on it [1,2]. Toluene(C7H8) diluted with H2+Ar gases were supplied togenerate precursors for depositing carbon films.

deposition rate at side (nm/min)

3. Results and Discussion
To examine effects of H atoms on deposition
profiles, we have studied dependence of deposition
rate on the side wall and the bottom of trenches on
the aspect ratio of trenches as a parameter ofdischarge power of the H atom source PH as shownin Fig. 1. For PH=0W, the deposition rate on theside and the bottom decreases with increasing theaspect ratio, while the deposition rate on the top
surface is independent of the aspect ratio (notshown here). The decrease of deposition rate on thesidewall is larger than that on the bottom. The
deposition rate for PH=500W is smaller than that for
PH=0W. An emission intensity of H from thedischarges increases with increasing PH. Theseresults indicate that the deposition profile isdetermined by the balance between carbon film
deposition by carbon containing radicals and carbon
25
R=89% 0W
R=33% 0W

20

R=89% 500W
R=33% 500W

15Fig.2. SEM image of deposition profile of carbon films.
Carbon films are deposited only at the top of the trench.
Conditions: R=11.1%, PH=500W, Ts=100oC.

10500120123aspect ratio
deposition rate at bottom (nm/min)film etching by H atoms. Moreover ion irradiation
modifies film structure and hence changes
deposition profile. For R= 33.3%, we have realized
carbon deposition only on the top of the trenches
above 1.6 in the aspect ratio at a low substratetemperature of 100oC. Figure 2 shows a typical
SEM image of the novel deposition profile. Thisdeposition profile is useful for selective depositionof carbon films on patterned substrates.

25
R=89% 0W
R=33% 0W

20

R=89% 500W
R=33% 500W

154. Conclusions
Low temperature deposition of carbon films
only on the top surface of trenches was realized byusing the H-assisted plasma CVD method. This
self-organized deposition is determined by thebalance between carbon film deposition by carbon
containing radicals and carbon film etching by H
atoms as well as modification of film structure byion irradiation.
Acknowledgment

10This work was partly supported by Core
Research for Evolutional Science and Technology(CREST) by the Japan Science and TechnologyAgency (JST).

500120123

aspect ratio

Fig. 1. Aspect ratio dependence of deposition rate attop, bottom, side of trenches. Conditions: substratetemperature 100oC, power of main discharge Pm = 45W, ion energy = 45 eV, total gas flow rate 90 sccm, H 2dilution ratio R=H2 / (H2+Ar) = 88.9% or 33.3%,
C7H8 2.5 sccm, pressure 13 Pa, PH = 0 W or 500 W.

References[1] J. Umetsu, K. Inoue, T. Nomura, H. Matsuzaki, K. Koga,M.Shiratani, Y.Setsuhara, M. Sekine, and M. Hori, J.
Plasma Fusion Res. SERIES 8, 1443 (2009).
[2] J. Umetsu, K. Koga, K. Inoue, H. Matsuzaki, K. Takenaka,
and M. Shiratani, Surface Coat． Technol. 202, 5659
(2008).