22P035P
Maskless Ultrafine Surface Modification onto Polymer Substrateby Atmospheric Pressure Plasma Jet with Nanocapillary
ナノキャピラリー大気圧プラズマジェットを用いたポリマー基板上へのマスクレス微細表面修飾
Michiyoshi Naito, Iuliana Motrescu*, Akihisa Ogino*, Futoshi Iwata*, Masaaki Nagatsu*
内藤 倫義, イウリアナ モトレスク*，荻野 明久*，岩田 太*，永津 雅章*
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 浜松市中区城北3-5-1*Graduate 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 浜松市中区城北3-5-1
The nano-sized low frequency driven atmospheric pressure plasma jet (APPJ) has been developed to apply
it to the maskless ultrafine process. In this study, we tried to apply it for the maskless micro-sized surface
modification onto polymer surface. From the optical emission spectroscopy of He/NH3 mixture plasma jet,
we observed the emission spectrum of NH (336.0 nm), which is considered to be a possible precursor ofamino group addition. Using the APPJ with a 1 μ mcapillary, we demonstrated the amino group
modification with a dot size of about 20 μm onto the polymer surface.

1. Introduction
Recently, many researches of various processes
using atmospheric pressure plasma jet (APPJ)
have been extensively carried out. This lowfrequency (LF) driven APPJ shows an interesting
plasma characteristic, known as “plasma bullet”[1]. Furthermore, owing to the non-thermal
equilibrium property, many applications to
low-temperature material processing are expectedunder atmospheric pressure [2, 3]. The size of an
APPJ generally ranges from mm order tohundreds nm. In this study, the selective small
area processing was performed using an APPJ
with a 1 m or 100 nm capillary [4].
So far, we have investigated the property ofatmospheric pressure helium (He) plasma jet withthe 100 nm capillary using an electrostatic probe
technique. We observed the propagation velocityof the plasma bullet ejected from the capillary.
The size of the plasma bullet was evaluated by
the etching pattern of photoresist film, which wasabout 500 nm from the results of the AFM
analysis [4].
In this study, we aim at developing themaskless ultrafine surface chemical modification
processing on the polymer surfaces using APPJ
with a micro or nano-capillary under atmosphericpressure.
2. Experimental setup
The schematic drawing of the experimental setup isshown in Fig. 1. A thin copper plate wound on theglass capillary was used as a powered electrode,which was connected to a high voltage pulse power
supply. In order to generate the plasma jet in a 0.6 mm
inner diameter glass capillary with a thickness of 0.2mm, He/NH3 mixture gas was flowed as the working
gas. The rectangular pulsed voltage at the duty ratio of
50% was applied on the electrode with maximum
voltage of ～±7.5 kV, and a frequency of 5 kHz. The
capillary used in this experiment were fabricated by
micropipette puller [4]. In the present experiments, thecapillaries with the aperture size of 1 μm and 100
nm were used. The ultrafine plasma jet was ejectedin the atmosphere by attaching micro- or
nano-capillary structure to a tip. In this experiment,Fig.1. The schematic of the experimental setupwe irradiated the plasma to the silicon substrate whichcoated the photo-resist film (OEBR-1000) which wasacrylic resin, and evaluated about the functional group
modification by surface observation using
fluorescence micro microscope.
3. Result
Figure 2 shows the experimental result of opticalemission spectroscopy (OES) measurement. Plasma
jet was generated on the condition of applied voltage:±6.5 kV, frequency: 5 kHz, pulse duty ratio: 50%. It
is noted that we used a larger size of capillary to getenough emission intensity to confirm the emission
spectrum in the OES measurement. Optical fiber forcollecting emission was located at 1mm from the tipof glass tube with 0.6 mm in diameter. From Fig. 2,
the emission spectrum of NH (336.0 nm) wasclearly seen. It is speculated that the emission
spectrum for micro-capillary APPJ is almost sameas the spectrum shown in Fig. 2. Therefore, theamino group introduction by NH and NH2
fragments are expected in a micro-sized small area
irradiated by micro-capillary APPJ.

surface. The distance between the capillary tip andthe substrate was kept at 250 μm. Figure 3(a) and3(b) shows the aminated dot pattern when we used theAPPJ with a single electrode and double electrodes,
respectively. From the present result, it is confirmedthat maskless amino group modification onto thepolymer surface was selectively made by amicro-capillary APPJ plasma jet with doubleelectrodes.

(a)00.1 0.2 0.3[mm]x100(b)00.1 0.2 0.3[mm]x100

Fig.3. Fluorescent patterns of aminated area treated with 1
m capillary plasma jet with (a) a single electrodeand (b) double electrodes.

Fig.2. Spectrum characteristic of He/NH3 mixture gas
plasma jet

To confirm the amino group introduction on thesurface, the fluorescence microscope observation wascarried out. In this measurement, fluorescent dyes are
selectively grafted with amino group. The grafted dyeemits fluorescent light of a specific wavelength of 520
nm excited by a light of shorter wavelength of 494 nm.
The used fluorescent dye for amino groupconfirmation is sulfodichlorophenyl ester.
Figure 3 shows the results of fluorescentobservation of the treated surface. The surface wasprepared by 2 step plasma treatments. In the first stepof treatment, the surface was biased at DC -500 V,
and then He plasma jet was irradiated for 0.1s. Afterthe first treatment, He/NH3 mixture gas plasma jet wasirradiated for 3 s to introduce amino groups on the4. Conclusion
We carried out the experiment of ultrafine
functional group modification onto the polymer
surface using APPJ with a micro-capillary. From
the OES results for He/NH3 mixture plasma jet, theemission spectrum of NH(336.0 nm) was observedin the downstream region. Moreover, the masklessamino group introduction onto the surface ofphotoresist film in a selected small area wasdemonstrated. The size of aminated area treated by1 m capillary APPJ with double electrodes wasabout 20 μm.
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