Ion energy distributions in a pulsed dual frequency inductively coupled discharge ofAr/CF4 and effect of duty ratioAnurag Mishra, Jin Seok Seo, Tae Hyung Kim, and Geun Young Yeom Citation: Physics of Plasmas 22, 083514 (2015); doi: 10.1063/1.4928442 View online: http://dx.doi.org/10.1063/1.4928442 View Table of Contents: http://scitation.aip.org/content/aip/journal/pop/22/8?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Role of the blocking capacitor in control of ion energy distributions in pulsed capacitively coupled plasmassustained in Ar/CF4/O2 J. Vac. Sci. Technol. A 32, 021306 (2014); 10.1116/1.4863948 Experimental investigations of electron density and ion energy distributions in dual-frequency capacitivelycoupled plasmas for Ar/CF 4 and Ar/O 2/CF 4 discharges J. Appl. Phys. 115, 013301 (2014); 10.1063/1.4859595 Space and phase resolved ion energy and angular distributions in single- and dual-frequency capacitivelycoupled plasmas J. Vac. Sci. Technol. A 31, 061311 (2013); 10.1116/1.4822100 Hydrogenated-amorphous carbon nitride films formed from the dissociative excitation reaction of CH 3 CN withthe microwave-discharge flow of Ar: Correlation of the [N]/([N]+[C]) ratio with the relative number densities of theCH (A 2 Δ) and CN (B 2 Σ + ) states J. Vac. Sci. Technol. A 22, 487 (2004); 10.1116/1.1690250 Effects of voltage distribution along an induction coil and discharge frequency in inductively coupled plasmas J. Vac. Sci. Technol. A 22, 293 (2004); 10.1116/1.1641052

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Ion energy distributions in a pulsed dual frequency inductively coupleddischarge of Ar/CF4 and effect of duty ratio

Anurag Mishra,1 Jin Seok Seo,1 Tae Hyung Kim,1 and Geun Young Yeom1,2,a)

1Department of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon,Gyeonggi-do 440-746, South Korea2SKKU Advanced Institute of Nanotechnology(SAINT), Sungkyunkwan University, Suwon,Gyeonggi-do 440-746, South Korea

(Received 11 November 2014; accepted 25 July 2015; published online 31 August 2015)

Controlling time averaged ion energy distribution (IED) is becoming increasingly important in

many plasma material processing applications for plasma etching and deposition. The present

study reports the evolution of ion energy distributions with radio frequency (RF) powers in a

pulsed dual frequency inductively discharge and also investigates the effect of duty ratio. The

discharge has been sustained using two radio frequency, low (P2 MHz¼ 2 MHz) and high

(P13.56 MHz¼ 13.56 MHz) at a pressure of 10 mTorr in argon (90%) and CF4 (10%) environment.

The low frequency RF powers have been varied from 100 to 600 W, whereas the high frequency

powers from 200 to 1200 W. Typically, IEDs show bimodal structure and energy width (energy

separation between the high and low energy peaks) increases with increasing P13.56 MHz; however,

it shows opposite trends with P2 MHz. It has been observed that IEDs bimodal structure tends to

mono-modal structure and energy peaks shift towards low energy side as duty ratio increases,

keeping pulse power owing to mode transition (capacitive to inductive) constant. VC 2015AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4928442]

I. INTRODUCTION

Plasma etching and deposition is an integral part of

semiconductor manufacturing industry, and ion bombarding

energy over the substrate is of critical importance, because it

determines the etch characteristics and properties of thin

films deposited.1 Controlling of ion energy is of particular

importance in plasma etching technology, because it should

be high enough to produce anisotropic etching but not too

high to cause sputtering, substrate damage, and loss of selec-

tivity. As the etching resolution increases and approaches to

monolayer, controlling of ion energy distribution (IED)

becomes much more important.2–4 In this context, induc-

tively coupled plasma (ICP) are of particular significance

due to having low plasma potential and thus provides a knob

for fine tuning of ion energy distributions.

Pulsing the discharge could enable more flexibility, and

therefore, the pulsed ICPs have recently attracted consider-

able interest in the field of integrated circuit fabrication.5–10

By pulsing either the ICP power or the radio frequency

(RF) bias power used to accelerate the ions toward the

wafer, or both, new plasma etching conditions could be

achieved, which provides more flexibility for tuning an etch

process by introducing new reactor control parameters such

as the pulsing frequency, the duty cycle of the pulses,

and the phase between the ICP and the bias pulses.

However, to have a fine control over discharge chemistry

suitable to a particular application requires a good under-

standing of the impact of these control parameters on the

plasma chemistry.

The shape of IEDs depends upon the response of ions to

the oscillating RF sheath, i.e., the ratio of ion transit time

through the sheath and time period of radio frequency.

Kawamura et al.11 analytically investigated the evolution of

IEDs in a radio frequency and showed that in collisionless

regime, the ratio sion/srf, where sion is the ion transit time

through the sheath and srf is the time period of the applied

radio frequency, determines the nature of sheath, the sheath

voltage waveform, and the shape of IEDs.

A recent review by Economou on tailored ion energy

distribution12 briefly revisited the techniques, such as

“tailored” voltage waveform on an electrode in continuous

wave plasma and an application of synchronous DC biased

boundary electrode during specified time windows in after-

glow region, to control ion energy distribution on a plasma

electrode. In a helicon plasma source experiment, Wang and

Wendt4 demonstrated the control on ion energy distribution

at the substrate by applying tailored bias voltage waveform,

consisting of a short voltage spike in combination with a

slow ramp. By using this technique, a much narrower IED

has been obtained compared to the conventional approach of

applying a sinusoidal waveform to the substrate electrode.

Based on time-dependent spherical-shell plasma fluid model,

they also demonstrated that this method is capable of produc-

ing narrow IEDs with precisely controllable energy inde-

pendent of ion mass. Using retarding field energy analyzer,

Shin et al.13 demonstrated that an efficient control over ion

energy distribution could be achieved by using a synchro-

nous pulsed or continuous wave biased boundary electrode

in pulsed inductively coupled plasma, without significantly

changing the bulk plasma properties. By varying DC voltage

on the boundary electrode from �8 to 12 V, a shift in energy

a)Author to whom correspondence should be addressed. Electronic mail:

gyyeom@skku.edu.

1070-664X/2015/22(8)/083514/7/$30.00 VC 2015 AIP Publishing LLC22, 083514-1

PHYSICS OF PLASMAS 22, 083514 (2015)

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peak from �10 to �25 eV has been achieved. A computa-

tional study on the synchronous DC biased boundary elec-

trode demonstrated similar results as in Refs. 13 and 14. An

energy resolved mass-spectrometric measurements in contin-

uous wave Ar/CF4 dual frequency ICP discharge reveals a

possibility of controlling IEDs by varying the high and low

frequency RF powers. It has been observed that both of the

frequencies have significant effect on IEDs of all prominent

discharge species. The evolution of IEDs with power shows

that the discharge undergoes a mode transition (E to H) as

the applied power is increased.15

Current prevailing trends in semiconductor manufactur-

ing industry are to fabricate device at nanolevels. However,

the fabrication cost increases as the device size shrinks, and

therefore, it becomes necessary to conduct the processing on

large area wafer size that poses the challenge to control the

uniformity of discharge flux over the substrate area. Many

schemes, based on multiple frequencies, power splitting

mechanism, pulse shape tailoring, and customized shape of

bias power, have been proposed.16–29 Recently, a new

approach, based on using dual frequency and power splitting

mechanism in ICP source, has been proposed to provide a

good discharge uniformity and control on discharge parame-

ters.30,31 Pulsing the plasma source provides an added flexi-

bility in controlling the discharge parameters and proves to

be an important tool for tailoring discharge parameters spe-

cific to a particular application. Moreover, in reactive plas-

mas, the duty ratio influences the discharge chemistry, which

in turn determines plasma parameters such as electron den-

sity, IEDs, and radical density. Therefore, it is of vital impor-

tance to understand discharge physics in pulsed mode, and

so, the present study makes an attempt to understand the evo-

lution of IEDs in a pulsed dual frequency discharge produced

by a plasma source as used in Refs. 30 and 31 and how IEDs

depend on the duty ratio of pulsing frequency.

II. EXPERIMENTAL SET-UP

The detailed description of the plasma source can be

found elsewhere.30 The plasma source comprises of two co-

centric planar-spiral coils made of copper tubes, having a total

diameter of 450 mm. Most of the substrate area (�80%) was

covered by inner coil. The inner coil (13 turns) and the outer

coil (2 turns) have been energized by a 2 and 13.56 MHz RF

powers, respectively. The low frequency (P2 MHz) and high

frequency (P13.56 MHz) powers have been varied from 100 to

600 W and 200 to 1200 W, respectively. The RF powers have

been fed to discharge via using two separate automatic match-

ing networks for 2 and 13.56 MHz powers. In the automatic

matching network units used in the present study, the change

in plasma load is fed-back by electronics control circuitry, and

then electronics control circuitry sends a message to a stepper

motor to change the capacitance by varying gap between the

two plates of vacuum variable capacitor used. Therefore, due

to this mechanical arrangement of adjusting capacitance, the

matching network may not be fast enough to follow abrupt

changes in plasma parameters, in the case of P2 MHz, and

hence the load to plasma generator. It might cause some error

in measurements of RF power fed into plasma during the pe-

riod, when P2 MHz is switched off. The RF powers fed to dis-

charge have been measured by using RF power meters in

between the RF generator and matching networks. Therefore,

the power measurements include power absorbed by the

plasma and power losses occurring in RF matching networks.

The schematic of experimental set-up with mass spectrometer

is shown in Figure 1. A cylindrical anodized aluminum cham-

ber with an inner diameter of 650 mm and a height of 400 mm

has been used in this study. A 35-mm-thick quartz window

was used to cover the top side of the processing chamber and

to hold the ICP source. The distance from RF window to sub-

strate could be adjusted, and in the present study, it has been

kept fixed at 90 mm.

FIG. 1. Schematic of the experimental

set-up and acquisition system.

083514-2 Mishra et al. Phys. Plasmas 22, 083514 (2015)

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The discharge has been operated in gas mixture of

Ar/CF4 with 10% contents of CF4 at a pressure of 10 mTorr.

The gases were evenly distributed in the vacuum chamber by

using a multi-hole shower ring located along the periphery

of the chamber. The base pressure less than 3� 10�6 mTorr

was routinely achieved by using a turbomolecular pump

backed by the dry pump.

In the present study, an energy resolved quadrupole mass

spectrometer (PSM003, supplied by Hiden Analytical, Ltd.)

has been used to measure IEDs. The ions have been sampled

into the mass spectrometer via an orifice of 100 lm in diame-

ter and then in a Bessel box energy filter at a pressure below

7� 10�7 Torr, achieved by using a differential pumping sys-

tem attached to mass spectrometer. The mass spectrometer has

been operated in a positive ion detection mode, which imple-

ments the scanning of the energy at a fixed mass-to-charge ra-

tio IEDs. To minimize the random error, every IED presented

in this study has been averaged over 5 individual scans.

The orifice of mass spectrometer has been placed at

30 mm below ICP source and 20 mm outside from edge of

the discharge volume. The QMS (Quadrupole Mass

Spectrometer) orifice was electrically grounded. The IEDs

have been collected in a time-averaged mode. There were

various ionic species in the discharge; however, CF2þ ionic

species has been analyzed in the present study, as it is very

important and dominating species.

To ensure the reproducibility and reliability of our meas-

urements, a number of test measurements have been carried

out before performing the real experiments. With variations

in the plasma power and pressure, the peak energy (most

probable energy, i.e., ions energy at maximum counts) of

plasma varies. Therefore, the mass spectrometer has been

tuned in such a way that instrument always operates at the

optimum energy conditions in positive ions detection mode.

To achieve it, a scan tree in mass spectrometer software

(MasSoft) has been designed in such a way that it obtains an

ion energy distribution for a chosen mass and then performs

a mass scan at the ion energy, which gives maximum signal,

after which the energy is set to give maximum signal. This

mass scan therefore acquires data at the peak energy deter-

mined in the energy scan.

III. RESULTS AND DISCUSSION

A. Influence of high frequency power levels on IEDs

Figure 2(a) shows ion energy distributions of CF2þ

species at a low frequency pulse power (instantaneous power

when pulse is “on”) of 100 W (P2 MHz¼ 100 W) and a pres-

sure of 10 mTorr. The high frequency power has been varied

from 200 to 1200 W (P13.56 MHz¼ 200–1200 W). The P2 MHz

has been pulsed at 1 kHz at a duty ratio of 50%, whereas

P13.56 MHz was in a continuous wave mode. It can be seen

FIG. 2. A plot evolution of IEDs with high frequency power levels (P13.56 MHz) at a fixed low frequency pulse power levels: (a) P2 MHz¼ 100 W, (b)

P2 MHz¼ 200 W, (c) P2 MHz¼ 300 W, and (d) P2 MHz¼ 400 W. The P13.56 MHz has been varied from 200 to 1200 W, and the pressure was kept constant at 10

mTorr. The P2 MHz has been pulsed at the frequency of 1 kHz with the duty ratio of 50%, whereas P13.56 MHz was in the continuous wave mode.

083514-3 Mishra et al. Phys. Plasmas 22, 083514 (2015)

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that the IEDs shown in Figure 2(a) have a bimodal structure,

a small low energy peak, and an intense high energy peak.

Typically, in the intermediate frequency regime (the dis-

charge conditions used in the present study) the ion transit

across the sheath is shorter than the low frequency time pe-

riod and much longer than the high frequency time pe-

riod.32,33 Therefore, ions respond to instantaneous low

frequency sheath potential, whereas to average high fre-

quency sheath potential, it makes IEDs bimodal and broad in

shape as observed in Figure 2(a). It can also be observed that

the low energy peak hardly shifts with P13.56 MHz; however,

the high energy moves towards high energy side making the

IEDs broad. This observation may be due to the fact that the

sheath potential corresponding to the low energy peak is

approximately equal to the floating potential,30 which is a

function of ion mass and electron temperature,34 and the

electron temperature does not vary significantly with P2 MHz

at similar operational parameters.32 Consequently, the low

energy peaks hardly shifts with increasing P2 MHz. However,

the maximum sheath potential increases with increasing

P13.56 MHz due to enhanced rf voltage on 13.56 MHz coil and

this is the reason why high energy peak shifts towards the

high energy side with increasing P13.56 MHz. The plasma also

increases with P13.56 MHz, and its effect is clearly visible in

Figure 2(a). As the P13.56 MHz, i.e., plasma density increases,

the shift of high energy peaks towards the high energy end

reduces (from 200 to 400 W, high energy peak shifts

�2.5 eV, but for 100–1200 W, it shifts by �1 eV). It is due

to the fact that discharge is transiting from capacitive to in-

ductive mode; however, it is still in the capacitive mode.

This is the reason that increasing P13.56 MHz does not affect

maximum sheath potential, and therefore, the high energy

peak keeps shifting, but with smaller energy shift, towards

high energy end.

The evolution of IEDs with P13.56 MHz at various value

of P2 MHz, 200, 300, and 400 W is shown in Figures 2(b) and

2(c). Figure 2(b) shows a plot of evolution of IEDs with

P13.56 MHz and at P2 MHz¼ 200 W. A quick comparison

between Figures 2(a) and 2(b) shows that main features in

IEDs shown in Figures 2(a) and 2(b) are similar; however,

energy spread slightly increases with P2 MHz and could be

attributed to a slight increase in RF voltage when P2 MHz

increases from 100 to 200 W. The peak counts in IEDs also

increase with P13.56 MHz (P13.56 MHz> 400 W) at P2 MHz

¼ 200 W due to enhanced density of CF2þ species. When

P2 MHz is further increased to 300 W, the low energy peak

becomes stronger, and IEDs acquires a bimodal saddle type

structure; however, the energy spread of IEDs remains simi-

lar as at P2 MHz¼ 200 W, as shown in Figure 2(c). At

P2 MHz¼P13.56 MHz¼ 200 W, the relative intensity of the

high energy peak is higher than that of the low energy peak,

and it decreases with increasing values of P13.56 MHz, acquir-

ing a mono-modal structure at P13.56 MHz¼ 1200 W. This

transition from saddle type bimodal to mono-modal struc-

tures of IEDs is due to the mode transition (capacitive to

inductive) due to enhancing plasma density. A further in

increase in P2 MHz (¼400 W) does not make any significant

change in IEDs shapes; however, the peak counts, i.e., the

density of radical increases as evident from Figure 2(d).

Figure 3 shows the variation of full width half maximum

(FWHM) of IEDs with low (P2 MHz) and high frequency

(P13.56 MHz) powers for the measurements shown in Figures

2(a)–2(d). The FWHM is the measure of energy spread and

could suggest about the discharge mode of operation. It can

be seen from the figure that the energy spread (FWHM)

initially increases with P13.56 MHz (200–400 W) and then

decreases beyond P13.56 MHz> 400 W. This trend is more evi-

dent at higher values of low frequency power (P2 MHz> 200

W). It suggests that initially the discharge is in the capacitive

mode, and beyond P13.56 MHz> 400 W, the discharge mode

changes and becomes inductive due to enhanced plasma

density.

B. Influence of low frequency power levels on IEDs

The evolution of IEDs with low frequency power

(P2 MHz) at various high frequency power levels (P13.56 MHz

¼ 100–500 W) has been shown in Figures 4(a)–4(e). Figure

2(a) shows the plot of IEDs at a fixed high frequency power

of 100 W. It can be seen that energy spread of IEDs

decreases as low frequency power P2 MHz increases. It can

also be observed that the IEDs contain dominant high energy

peak and the high energy peak shifts towards low energy end

with increasing P2 MHz. It can be understood as follows. The

plasma density increases with increasing P2 MHz27,28 and that

reduces the average sheath voltage; therefore, ions traversing

through the sheath get lower energy from the sheath, result-

ing in lower energy of second peak. The central coil ener-

gized by P2 MHz plays a dominant role in this plasma source

as most of source area is covered by it. So, as P2 MHz

increases, there is a significant change in the plasma density

at the comparable powers of P13.56 MHz. Therefore, the mode

transition from capacitive to inductive is observed with

increasing P2 MHz. This is the reason why high energy peaks

shift towards the high energy side in the beginning, indicat-

ing strengthening capacitive mode, and then shifts towards

FIG. 3. A plot full width and half maximum (FWHM) variation with high

frequency levels (P13.56 MHz) at four low frequency pulse powers of 100,

200, 300, and 400 W. The P13.56 MHz has been varied from 200 to 1200 W,

and pressure was kept constant at 10 mTorr. The P2 MHz has been pulsed at

the frequency of 1 kHz with the duty ratio of 50%, whereas P13.56 MHz was in

the continuous wave mode.

083514-4 Mishra et al. Phys. Plasmas 22, 083514 (2015)

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the low energy side, indicating mode transition phase from

capacitive to inductive.

A plot of IEDs with low frequency levels at a fixed high

frequency power of 200 W has been shown in Figure 4(b).

The IEDs attain a bimodal shape, and the low energy peak

becomes stronger with increasing low frequency power

P2 MHz, and the high energy peak slightly shifts towards the

low energy end. The strengthening the low energy peak is

due to the increased density that increases ion-neutral and

ion-ion collisional frequency, resulting in thermalization of

ions. The slight shift in the high energy peak with increasing

P2 MHz is speculated due to a slight change in average sheath

potential. The plots of IEDs at P13.56 MHz of 300, 400, and

500 W have been shown in Figures 4(c)–4(e). The main

FIG. 4. A plot evolution of IEDs with low frequency power levels (P13.56 MHz) at a fixed high frequency pulse power levels: (a) P13.56 MHz¼ 100 W, (b)

P13.56 MHz¼ 200 W, (c) P13.56 MHz¼ 300 W, (d) P13.56 MHz¼ 400 W, and (e) P13.56 MHz¼ 500 W. The P2 MHz has been varied from 100 to 600 W, and the pressure

was kept constant at 10 mTorr. The P2 MHz has been pulsed at the frequency of 1 kHz with the duty ratio of 50%, whereas P13.56 MHz was in the continuous

wave mode.

083514-5 Mishra et al. Phys. Plasmas 22, 083514 (2015)

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features in Figures 4(c)–4(e) is similar as in Figure 4(b)

except that stronger low energy peaks and higher peak

counts due to enhancing CF2þ density.

C. Influence of duty ratio on IEDs

Figure 5(a) shows the variation in IEDs with duty ratio.

The discharge has been operated at a pressure of 10 mTorr

and pulsed at a frequency (2 MHz) of 1 kHz. The applied

P13.56 MHz was 400 W in the continuous wave mode. The

pulse power of low frequency P2 MHz was kept fixed at

400 W. It can be observed from Figure 5(a) that the bimodal

structure of IEDs tends to be mono-modal, the low energy

peak diminishes, and the high energy peak shifts towards

low energy end, and as the duty ratio is increased from 20%

to 90%, the peak count also increases. In the pulsed ICP

discharge, one of origins of low energy ions is afterglow

region.35 As the duty ratio is increased, the length of

afterglow region reduces, resulting in diminishing of the low

energy peak. The shift of high energy peak towards the low

energy end is due to increasing CF2þ density, enhancing

ion-ion and ion-neutral collisions. Figure 5(b) shows a plot

of energy integrated counts of CF2þ, which is a measure of CF2

þ density, and confirms the enhancing CF2þ density with

the duty ratio. Observed increasing trend in CF2þ is due to

the fact that increased average power as pulse has been kept

constant while varying the duty ratio.

Figure 6 shows the variation in IEDs with the duty ratio

on the same condition as for Figure 5(a) except the low fre-

quency pulse power has been changed to keep the average

low frequency power of 400 W constant. It can be seen from

Figure 6 that the energy width (separation between two

energy peaks) reduces from �15 to �8 eV and high energy

peaks shifts from �18 to �13.5 eV, when the duty ratio is

increased from 25% to 75% for the same reason as explained

earlier.

IV. CONCLUSIONS

Mass resolved ion energy distributions have been meas-

ured in pulsed dual frequency inductively coupled discharge.

Typical structure of IEDs is bimodal, and it tends to be

mono-modal type with increasing rf power. The energy

spread, energy width, and average sheath potential increases

with increasing high frequency power, whereas it shows

reverse trends with the low frequency power. The increasing

trends in the energy spread, energy width, and average

sheath potential with increasing high frequency power are

speculated to be due to increasing rf voltage on the high fre-

quency rf coil, whereas the decreasing trends of same param-

eters with the low frequency power are attributed to the

increasing plasma density.

An investigation to understand the effect of duty ratio

on IEDs evolution shows that the shape of IEDs changes

from bimodal to mono-modal as the duty ratio increases.

ACKNOWLEDGMENTS

This work was supported by the Industrial Strategic

technology development program (10041926, Development

of high density plasma technologies for thin film deposition

FIG. 5. (a) A plot evolution of IEDs and (b) of variation of energy integrated

counts with duty ratio. The duty ratio have been varied from 20% to

90%.The low frequency pulse power (P2 MHz) and the high frequency power

(P13.56 MHz), both were kept fixed at 400 W. The operating pressure was 10

mTorr. The P2 MHz has been pulsed at the frequency of 1 kHz with the duty

ratio of 50%, whereas P13.56 MHz was in the continuous wave mode.

FIG. 6. A plot of evolution of IEDs with three chosen duty ratios of 25%,

50%, and 75%. Both the low frequency average power (P2 MHz) and the high

frequency power (P13.56 MHz) were kept fixed at 400 W. The operating pres-

sure was 10 mTorr. The P2 MHz has been pulsed at the frequency of 1 kHz

with the duty ratio of 50%, whereas P13.56 MHz was in the continuous wave

mode.

083514-6 Mishra et al. Phys. Plasmas 22, 083514 (2015)

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for nanoscale semiconductor and flexible display processing)

funded by the Ministry of Knowledge Economy (MKE,

Korea).

This work was also partially supported by the International

Joint Research and Development Program (N009300229,

Large area PECVD Equipment development for Flexible low

temperature high density film deposition) funded by the

Ministry of Knowledge Economy(MKE, Korea).

1M. A. Lieberman and A. J. Lichtenberg, Principles of Plasma Dischargesand Materials Processing (Wiley, New York, 1994).

2L. Xu, D. J. Economou, V. M. Donnelly, and P. Ruchhoeft, Appl. Phys.

Lett. 87, 041502 (2005).3S. B. Wang and A. E. Wendt, J. Vac. Sci. Technol., A 19, 2425 (2001).4S. B. Wang and A. E. Wendt, J. Appl. Phys. 88, 643 (2000).5S. Banna, A. Agarwal, G. Cunge, M. Darnon, E. Pargon, and O. Joubert,

J. Vac. Sci. Technol., A 30, 040801 (2012).6A. Agarwal, P. Stout, S. Banna, S. Rauf, and K. J. Collins, J. Vac. Sci.

Technol., A 29, 11017 (2011).7A. Agarwal, P. Stout, S. Banna, S. Rauf, K. Tokashiki, J. Y. Lee, and K.

Collins, J. Appl. Phys. 106, 103305 (2009).8A. Mishra, J. S. Seo, K. N. Kim, and G. Y. Yeom, J. Phys. D: Appl. Phys.

46, 235203 (2013).9P. Subramonium and M. J. Kushner, Appl. Phys. Lett. 79, 2145 (2001).

10C. Petit-Etienne, M. Darnon, L. Vallier, E. Pargon, G. Cunge, F. Boulard,

O. Joubert, S. Banna, and T. Lill, J. Vac. Sci. Technol., B 28, 926 (2010).11E. Kawamura, V. Vahedi, M. A. Lieberman, and C. K. Birdsall, Plasma

Sources Sci. Technol. 8, R45 (1999).12D. J. Economou, J. Vac. Sci. Technol., A 31(5), 050823 (2013).13H. Shin, W. Zhu, L. Xu, V. M. Donelly, and D. J. Economou, Plasma

Sources Sci. Technol. 20, 055001 (2011).14M. D. Logue, H. Shin, W. Zhu, L. Xu, V. M. Donelly, D. J. Economou,

and M. J. Kushner, Plasma Sources Sci. Technol. 21, 065009 (2012).15N. Kang and F. Gaboriau, J. Phys. D: Appl. Phys. 44, 442001 (2011).16Y. Yang and M. J. Kushner, J. Appl. Phys. 108, 113306 (2010).

17S. P. Hong, J. H. Lim, G. H. Gweon, and G. Y. Yeom, Jpn. J. Appl. Phys.,

Part 1 49, 080217 (2010).18K. N. Kim, J. H. Lim, G. Y. Yeom, S. H. Lee, and J. K. Lee, Appl. Phys.

Lett. 89, 251501 (2006).19G. H. Gweon, J. H. Lim, K. N. Kim, S. P. Hong, T. H. Min, and G. Y.

Yeom, Vacuum 84, 823 (2010).20J. H. Lim, K. N. Kim, G. H. Gweon, J. B. Park, and G. Y. Yeom, Plasma

Chem. Plasma Process. 29, 251 (2009).21K. N. Kim, J. H. Lim, and G. Y. Yeom, Jpn. J. Appl. Phys., Part 1 48,

116006 (2009).22K. N. Kim, J. H. Lim, W. S. Lim, and G. Y. Yeom, IEEE Trans. Plasma

Sci. 38(2), 133 (2010).23J. H. Lim, K. N. Kim, J. K. Park, J. T. Lim, and G. Y. Yeom, Appl. Phys.

Lett. 92, 051504 (2008).24Y. Setsuhara, K. Takenaka, A. Ebe, and K. Nishisaka, Plasma Processes

Polym. 4, S628 (2007).25J. H. Lim, K. N. Kim, and G. Y. Yeom, Plasma Processes Polym. 4, S999

(2007).26F. F. Chen and J. P. Chang, Lecture Notes on Principles of Plasma

Processing (Kluwer/Plenum, New York, 2002).27M. A. Lieberman, J. P. Booth, P. Chabert, J. M. Rax, and M. M. Turner,

Plasma Sources Sci. Technol. 11, 283 (2002).28P. Chabert, J. Phys. D: Appl. Phys. 40, R63 (2007).29V. Volynets, H. Shin, D. Kang, and D. Sung, J. Phys. D: Appl. Phys. 43,

085203 (2010).30A. Mishra, K. N. Kim, T. H. Kim, and G. Y. Yeom, Plasma Sources Sci.

Technol. 21, 035018 (2012).31A. Mishra, T. H. Kim, K. N. Kim, and G. Y. Yeom, J. Phys. D: Appl.

Phys. 45, 475201 (2012).32T. V. Rakhimova, O. V. Braginsky, V. V. Ivanov, A. S. Kovalev, D. P.

Lopaev, Y. A. Menkelevich, M. A. Olevanov, O. V. Proshina, A. T.

Rakhimov, A. N. Vasilieva, and D. G. Voloshin, IEEE Trans. Plasma Sci.

35(5), 1229 (2007).33E. A. Edelberg and E. S. Aydil, J. Appl. Phys. 86(9), 4799 (1999).34X. Jiang, Y. Liu, S. Yang, W. Lu, Z. Bi, X. Li, and Y. Yang, J. Vac. Sci.

Technol., A 29(1), 011006 (2011).35M. Brihoum, G. Cunge, M. Darnon, D. Gahan, O. Joubert, and N. J.

Braithwaite, J. Vac. Sci. Technol., A 31(2), 020604 (2013).

083514-7 Mishra et al. Phys. Plasmas 22, 083514 (2015)

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