22G15
Development of Low-Damage Reactive Sputter Deposition Processes
with Inner-Type Low Inductance Antenna
埋込型低インダクタンスアンテナによる低ダメージ反応性スパッタ製膜プロセスの開発
Yuichi Setsuhara1, Ken Cho1, Kosuke Takenaka1 and Akinori Ebe2
節原裕一1, 趙 研1，竹中 弘祐1，江部明憲1
1

Joining and Welding Research Institute, Osaka University,
11-1 Mihogaoka,Ibaraki-shi, Osaka, 567-0047, Japan
2
EMD Corporation,
36 Kisshouin Ishihara Dounoushiro-cho, Minami-ku, Kyoto 601-8355, Japan1
大阪大学接合科学研究所〒567-0047 大阪府茨木市美穂ヶ丘11-1
2
株式会社イー・エム・ディー〒601-8355 京都市南区吉祥院石原堂ノ後町36番地
Discharge properties have been investigated for inductively coupled RF plasmas (ICP) sustained with
inner-type low-inductance antennas (LIAs). The inner-type LIA has been developed as a new-type ofLIA, in which an RF antenna conductor with a length much shorter than the RF wavelength is embedded ina hall region dug in the chamber wall and the dielectric window plate is installed at the same height of thechamber-wall inner surface as an insulator for shielding the antenna conductor from the plasma. The
discharge technology with the inner-type LIA has been applied to ICP-assisted magnetron sputtering withan attempt to attain low-damage reactive sputtering process for advanced deposition of functional films todevelop flexible electronics.

1. Introduction
High-quality
devicefabrications
withinorganic/organic hybrid structures are desired
for advanced applications including flexibleelectronics.
For successful development ofthese processes in large-area processes, it is ofkey importance to employ plasma production andcontrol technologies with capabilities of lowdamage process and excellent uniformity overlarge area. In our previous investigations forlarge-area plasma processes, inductivity-coupledplasma (ICP) sources have been developed withmultiple low-inductance antenna (LIA) modules[1-3]. The LIA module consisted of an internal
RF antenna with dielectric isolation, whichallowed low-voltage and high-density plasma
production.
For application to ICP-assisted magnetron
sputtering process [4,5], an inner-type LIA [6]has been developed as a new-type of LIA, inwhich an RF antenna conductor with a length
much shorter than the RF wavelength isembedded in a hall region dug in the chamber
wall and the dielectric window plate is installed atthe same height of the chamber-wall inner surface
as an insulator for shielding the antenna
conductor from the plasma, as shown in Fig. 1with conventional LIA for comparison.
Since the conventional LIA has the shape that issalient toward the plasma region from the chamberwall inner surface, this new type of the LIA shownin Fig. 1 is called as "inner-type LIA". Special
feature of the ICP-assisted magnetron with theinner-type LIA is that the ICP antenna is located at
the same height or beneath the target surface of themagnetron.
In the conventional designs of the plasmaassisted magnetrons [7], additional plasma sources
are located in the region between the target and thesubstrate, thus the target-substrate distance iselongated due to the installation of the additional

Fig.1
Schematicillustrations
conventional and (b) inner-type LIA.

of(a)Plasma production with inner-type LIA
2

RF power (13.56 MHz)Ion satuation current density (mA / cm )Inner-type LIA

Fig.2 Schematic illustrations of ICP-assisted
magnetron sputtering deposition system with
inner-type LIA.
plasma source.
As a result, the conventional
configuration of the plasma-assisted magnetronsuffers loss of deposition rate
In this presentation, basic performance of theplasmas sustained with LIAs will be reported
together with applications to plasma-enhanced
sputter deposition for formation of microcrystalline
silicon films and oxide semiconductor films.
2. Experiment
Discharge properties of ICPs sustained with theinner-type LIA were examined by installing one setof the inner-type LIA with an RF conductor lengthof 100 mm in a vacuum chamber with a diameter of
500 mm.
Ion saturation current and floating
potential were measured in an Ar plasma sustainedat pressures of 1.3-6.5 Pa.
For ICP-assisted
magnetron sputtering, two sets of the inner-type
LIA with an RF conductor length of 150 mm were
installed beside a magnetron sputtering source, as
schematically shown in Fig. 2. In the ICP-assisted
magnetron sputtering, an un-doped Si target with ahigh electrical resistivity was employed as thesputtering target for deposition of intrinsic siliconlayer.
3. Results and discussion
Fig. 3 shows the ion saturation current and thefloating potential (DC and oscillation components)
for argon plasmas sustained with the inner-type LIA.
The ion saturation current increased almost linearlywith increasing RF, and the achieved plasma
density is as high as on the order of 1011 cm-3.
Furthermore, the floating potential measurements
show that the plasma generation with significantly
suppressed potential fluctuation has been attained,
as in the conventional LIAs [1-3].
In the ICP-assisted magnetron sputteringexperiments, it has been shown that the flux of thedeposited atoms can be controlled independently
via target voltage, while the flux of the reactivespecies (in this case oxygen radicals and ions) can(a)pAr = 6.5 Pa

86pAr = 1.3 Pa

420050100150
RF power (W)200250Inner-type LIA
Ar pressure = 2.6 Pa, z = 120 mm
12(b)DC component

10Floating potential (V)Magnetron

10864Oscillation component

200100200

300

400500RF power (W)Fig.3 Ion saturation current and floating
potential measured for Ar plasmas sustainedwith inner-type LIA.
be kept almost constant in the ICP sustained withthe constant RF power. Especially, this feature of
the independent and fine control capability of theflux ratio is very much significant for high-quality
film deposition to control flux ratio of the excitedspecies (radicals and ions) to the deposited atoms
Acknowledgments
This research was partly supported by Adaptable
and Seamless Technology Transfer Program(ASTEP), Japan Science and Technology Agency(JST).
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