22P034-P
Effect of Hydrogen Addition on Copper Film Deposition
Using Atmospheric Pressure Plasma Jet
大気圧プラズマジェットを用いた銅薄膜堆積における水素添加の効果
Hisashi Nakahiro1, Akihisa Ogino2, Wei Zheng3, and Masaaki Nagatsu2
中廣 尚志1，荻野 明久2，鄭 偉3，永津 雅章2
1

Graduate School of Engineering, Shizuoka University,
3-5-1, Johoku, Nakaku, Hamamatsu 432-8561, Japan
静岡大学大学院工学研究科電気電子工学専攻，〒432-8561 浜松市城北3-5-1
2Graduate School of Science and Technology, Shizuoka University,
3-5-1, Johoku, Nakaku, Hamamatsu 432-8011, Japan
静岡大学創造科学技術大学院，〒432-8011 浜松市城北3-5-13Research and Technology Center, Yazaki Corp.,
矢崎総業株式会社
Copper thin films were deposited by using atmospheric pressure plasma jet in air. To prevent the oxidationof deposited film, the effect of H2 addition as a plasma-gas was studied. The plasma jet was driven by radio
frequency (RF, 13.56 MHz), and ignited by applying RF power of 300 W to the coil after plasma-gas
introduction (Ar:1000 sccm, H2:10 sccm). The characterization of copper films was curried out withscanning electron microscopy and X-ray spectrometry.

1. Introduction
Atmospheric plasma process has a great
advantage for the treatment of the heat sensitive
substrates under pump-free condition or theselective treatments and modifications for complex
plasma treatment of three-dimensional work.
Another demand of atmospheric pressure material
processing is to realize fine-structured processing ofelectronic device fabrication [1]. Up to now, in the
fabrication of the most of ultra-fine electronicdevices, the dry plasma processing at low pressure
has been widely used. However, the plasma
processing in air is still restricted to a small numberof applications that the oxidation does not adversely
affect. The deposition process using atmosphericpressure plasma can be attained by feeding plasma
gas containing a source gas for deposition [2,3].
One of important issue in plasma processing, suchas metal film depositions, is the oxidation of thematerial and the film surface during the process inatmospheric air [4,5]. To apply atmosphericpressure plasma technique to metal film deposition
for electronic devices, the decrease in oxidation ofdeposited material is important. In this study, thecopper (Cu) thin films were deposited by using
atmospheric pressure plasma jet in air. To preventthe oxidation of deposited film, the effect of H2addition as a plasma-gas was studied.

atmospheric pressure plasma jet. The plasma jet
was driven by radio frequency (RF, 13.56 MHz)and jetted out from a quartz nozzle (3 mm outerdiameter). The nozzle was connected to Ar and H2
gas feed line for plasma-gas introduction. A Cu wire
1 mm in diameter was employed as a source for thedeposition and inserted into the quartz nozzle. A
4-turns solenoid coil made of Cu tube was woundaround the quartz tube. The plasma was ignited byapplying RF power of 300 W to the coil after
plasma-gas introduction (Ar:1000 sccm, H2:10sccm). The inserted Cu wire was heated andevaporated by plasma, and then Cu film wasdeposited on a substrate which was set from thenozzle tip of 1 mm.

2. Experimental setup
Figure 1 shows the schematic drawing ofexperimental setup for Cu film deposition using

Fig. 1. Schematic drawing of experimental setup forcopper film deposition using atmospheric pressureplasma jet.

High voltage
DC power supply

Gas:Ar or Ar+H2

Quartz tubeCu wireRF(13.56MHz)
generator

Solenoidcoil (4-turns)
PlasmaSubstratezMatching
network

Pulse
generator

3. Results and discussion
Figure 2 shows the emission spectra at the quartz
nozzle tip measured in the visible ranges. Though
no optical emission from Cu atom was detected in
the visible range shown in Fig.2(a), the Cu emission
at 324.8 nm was obviously observed after installinga Cu wire on the central axis. Moreover, the Cu
emission intensity increased by adding a small
amount of H2 to Ar, and the peak intensity ofatmospheric gases such as N2 and O2 decreased.
The emission intensity of Ar slightly decreased byadding of H2. The decrease in the emission intensityof Ar corresponds to the decrease in the length ofplasma jet.

Intensity (arb. unit)(a) Ar plasmaO(777.2)

N2SPS(b) Ar plasma with Cu

Ar ICu(324.8)(c) Ar+H 2(10sccm) plasma with Cu

300

Ar
Ar/H2 ②CuO,① Cu, Cu2OCu(OH)2③ CuO satellite

20
10185
140950940
930
Binding energy (eV)Fig. 3. XPS spectrum in Cu 2p3/2 regions of thesurface deposited by Ar and Ar/H2 atmospheric pressureplasma jet.

OH(308.9)

Cu(324.8)

eV corresponding to Cu and/or Cu2O [6,7].
Moreover, another component around 935.2 eV
which assigned to CuO and/or Cu(OH)2 wasdecreased by H2. The formation of Cu oxide is dueto the oxidation reactions of Cu with O2, excitedoxygen and water vapor in air.

Intensity (arb. unit)

The effects of H2 adding on plasma process wereevaluated from optical emission spectroscopy(OES). The film characterization was also observedwith XPS. The analyzed depth of XPS analysis isexpected to be roughly a few nanometers from thesurface.

400500600
700800
Wavelength (nm)Fig. 2. Optical emission spectra obtained during
deposition at the quartz nozzle tip. (a) Ar plasma without
Cu wire, (b) Ar plasma with Cu wire on the tube axis,and (c) Ar and H2 gas mixture plasma with Cu wire.

To obtain the surface information on thechemical composition, the deposited surfaces wereanalyzed with XPS. Typical XPS spectrum in Cu
2p3/2 of the film is shown in Fig. 3. The sharp Cu
peak was obviously observed when small amount ofH2 gas was introduced in Ar. In the case of H2 gas
addition, a component was clearly detected at 933.1

4. Conclusion
In this study, the experimental results of the Cu
film deposition using atmospheric pressure plasmajet. The Cu film deposition was carried out on thesubstrate installed in air. According to OES
measurement, the Cu emission intensity at 324.8
nm increased by adding of H2, and the peakintensity of atmospheric gases decreased.
According to XPS measurement, the oxidation ofCu film during deposition was prevented by H2
addition in plasma. The obtained results show thepossibility of atmospheric plasma processing formetal film deposition. The other results and detail
discussion will be presented at the conference.
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