Experimental research of ICP reactor for plasma-chemical etching
The results of systematic experimental researches of plasma-chemical etching reactor in the inductive mode are presented in this paper. Measurements of the integral discharge parameters (inductor voltage, gas pressure, input power) have been carried out as well as probe measurements of spatial d...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2006
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| Цитувати: | Experimental research of ICP reactor for plasma-chemical etching / S.V. Dudin, A.V.Zykov, A.N.Dahov, V.I. Farenik // Вопросы атомной науки и техники. — 2006. — № 6. — С. 189-191. — Бібліогр.: 3 назв. — англ. |
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irk-123456789-822892015-05-28T03:02:21Z Experimental research of ICP reactor for plasma-chemical etching Dudin, S.V. Zykov, A.V. Dahov, A.N. Farenik, V.I. Low temperature plasma and plasma technologies The results of systematic experimental researches of plasma-chemical etching reactor in the inductive mode are presented in this paper. Measurements of the integral discharge parameters (inductor voltage, gas pressure, input power) have been carried out as well as probe measurements of spatial distribution of local plasma parameters (plasma density, temperature and electron energy distribution function) and radial profiles of ion current to processed surface. The measured dependences differ essentially for atomic (Ar) and molecular (O₂,N₂,CF₄) gases. As the range of working pressure covers diffusive and collisionless modes of charged particles movement, radial distribution of ion current density and its absolute value change significantly. Comparison of the obtained results with the calculations executed using “Global” spatially averaged model and 2D-fluid model is carried out. 2006 Article Experimental research of ICP reactor for plasma-chemical etching / S.V. Dudin, A.V.Zykov, A.N.Dahov, V.I. Farenik // Вопросы атомной науки и техники. — 2006. — № 6. — С. 189-191. — Бібліогр.: 3 назв. — англ. 1562-6016 PACS: 52.77.Bn http://dspace.nbuv.gov.ua/handle/123456789/82289 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
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English |
| topic |
Low temperature plasma and plasma technologies Low temperature plasma and plasma technologies |
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Low temperature plasma and plasma technologies Low temperature plasma and plasma technologies Dudin, S.V. Zykov, A.V. Dahov, A.N. Farenik, V.I. Experimental research of ICP reactor for plasma-chemical etching Вопросы атомной науки и техники |
| description |
The results of systematic experimental researches of plasma-chemical etching reactor in the inductive mode are presented
in this paper. Measurements of the integral discharge parameters (inductor voltage, gas pressure, input power)
have been carried out as well as probe measurements of spatial distribution of local plasma parameters (plasma density,
temperature and electron energy distribution function) and radial profiles of ion current to processed surface. The
measured dependences differ essentially for atomic (Ar) and molecular (O₂,N₂,CF₄) gases. As the range of working
pressure covers diffusive and collisionless modes of charged particles movement, radial distribution of ion current density
and its absolute value change significantly. Comparison of the obtained results with the calculations executed using
“Global” spatially averaged model and 2D-fluid model is carried out. |
| format |
Article |
| author |
Dudin, S.V. Zykov, A.V. Dahov, A.N. Farenik, V.I. |
| author_facet |
Dudin, S.V. Zykov, A.V. Dahov, A.N. Farenik, V.I. |
| author_sort |
Dudin, S.V. |
| title |
Experimental research of ICP reactor for plasma-chemical etching |
| title_short |
Experimental research of ICP reactor for plasma-chemical etching |
| title_full |
Experimental research of ICP reactor for plasma-chemical etching |
| title_fullStr |
Experimental research of ICP reactor for plasma-chemical etching |
| title_full_unstemmed |
Experimental research of ICP reactor for plasma-chemical etching |
| title_sort |
experimental research of icp reactor for plasma-chemical etching |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2006 |
| topic_facet |
Low temperature plasma and plasma technologies |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/82289 |
| citation_txt |
Experimental research of ICP reactor for plasma-chemical etching / S.V. Dudin, A.V.Zykov, A.N.Dahov, V.I. Farenik // Вопросы атомной науки и техники. — 2006. — № 6. — С. 189-191. — Бібліогр.: 3 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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| first_indexed |
2025-07-06T08:47:42Z |
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2025-07-06T08:47:42Z |
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| fulltext |
Problems of Atomic Science and Technology. 2006, 6. Series: Plasma Physics (12), p. 189-191 189
EXPERIMENTAL RESEARCH OF ICP REACTOR
FOR PLASMA-CHEMICAL ETCHING
S.V. Dudin1, A.V.Zykov1, A.N.Dahov2, V.I. Farenik2
1 V.N. Karazin Kharkiv National University, 31 Kurchatov ave., 61108, Kharkiv, Ukraine;
2Scientific Center of Physical Technologies, 6 Svobody Sq., 61007, Kharkiv, Ukraine
The results of systematic experimental researches of plasma-chemical etching reactor in the inductive mode are pre-
sented in this paper. Measurements of the integral discharge parameters (inductor voltage, gas pressure, input power)
have been carried out as well as probe measurements of spatial distribution of local plasma parameters (plasma density,
temperature and electron energy distribution function) and radial profiles of ion current to processed surface. The
measured dependences differ essentially for atomic (Ar) and molecular (O2,N2,CF4) gases. As the range of working
pressure covers diffusive and collisionless modes of charged particles movement, radial distribution of ion current den-
sity and its absolute value change significantly. Comparison of the obtained results with the calculations executed using
“Global” spatially averaged model and 2D-fluid model is carried out.
PACS: 52.77.Bn
1. INTRODUCTION
Last years ICP became the conventional basis for
creation of various plasma technological devices, in par-
ticular for plasma-chemical etching in microelectronics
[1]. By the present moment great progress have been
achieved both in the field of basic research of ICP physics
and in the field of practical reactor design, and focus of
ICP application is shifted to development of the techno-
logical devices optimized for specific micro- and
nanotechnologies with high requirements to the device
parameters. It is impossible to satisfy these requirements
without detailed experimental researches and improve-
ment of ICP mathematical models.
This paper reports the results of systematic ex-
perimental researches of the universal module of plasma-
chemical and ion-plasma etching based on ICP reactor
with additional RF electrode biasing developed in the
Kharkiv National University.
2. EXPERIMENTAL SETUP
A schematic diagram of the experimental setup used
in our investigation is shown in Fig. 1. The discharge ves-
sel has a radius R = 7 cm and height L = 6 cm. The side-
wall of the vessel is made of metal. The glass top cover
and the inductive coil is cooled by air flow created by a
fan. The vessel is evacuated by a turbomolecular pump
down to a base pressure of about 10-6 Torr. The ex-
periments were performed using argon in the pressure
range 0.3…300 mTorr.
The RF eld is induced by a three-turn spiral copper
coil cooled by air. The capacitive coupling is damped by a
grounded electrostatic shield. RF power in the range
50…500 W at 13.56 MHz is coupled to the coil via a
matchbox.
Measurement of the ion current density j was carried
out adjacent to the grounded work surface, here a sub-
strate holder, using a at probe of 1×1 cm with 5mm mica
guard ring around added to avoid edge effects. We as-
sume here that the probe current in mA represents the ion
current density in mA/cm2. The probe could be moved in
the radial direction by a coordinate drive. Second probe of
the same design was mounted stationary on the chamber
side wall (see Fig.1) allowing j measurement during etch-
ing process. The ion saturation regime was used. In the
power range of interest the thickness of the near-probe
layer is negligible in comparison with the probe dimen-
sions, and is justi ed by excellent probe current saturation
at probe potentials lower than -15 V. On the other hand,
much more negative potentials may cause ionization cur-
rent gain under high pressures. Thus, in all experiments a
negative probe bias of -25 V in respect to the chamber
was used.
3. EXPERIMENTAL RESULTS
3.1. ARGON
Typical radial pro les of the ion current density j at
the substrate holder are presented in Fig. 2 at various ar-
gon pressures. Measurements were carried out at RF
power of 200 W. It has been found, that in the power
range 50-500W j is proportional to the power, and shape
of radial profile j (r) practically does not change.
As shown in Fig. 2, for pressure p < 20 mTorr the ra-
dial pro le of j is convex, maximizing at the discharge
axis. For p < 5 mTorr, the pro le remains practically un-
changed with further pressure decrease, only its magni-
tude changes. For p > 20 mTorr, the j pro le becomes
concave, with off-axis maximums. In this range the ratio
of the peak density to the axis density increases with the
pressure. There is relatively high uniformity of j in the
region r < 0.8R for p 200 mTorr.
Fig. 1. Schematic diagram of the ICP reactor
190
The dependence of j at r = 0 on the neutral gas pres-
sure is shown in Fig. 3, in comparison with theoretical
results. In the figure two regions are clearly seen: 1) low
pressure region where mean free path of the charged par-
ticles is comparable or higher then the plasma dimen-
sions, so the particle motion is mostly collisionless;
2) high pressure region where the mean free path is lower,
particle motion is collisional, and diffusive approach is
more appropriate.
It is also found that the magnitude of j is proportional
to the RF power absorbed by plasma and the shape of the
j radial pro le has weak dependence on the power value.
3.2. MOLECULAR GASES
On Fig. 4, 5 dependences of the ion saturation current
of the wall probe j, amplitude of the inductor RF voltage
Uind on pressure of working gas at RF power = 200W
for different gases are presented. Apparently from the
graphs the dependences are essentially different for argon
and for the molecular gases. We have monotonic j in-
crease and Uind decrease with pressure growth for argon,
whereas for molecular gases both at high and at low pres-
sures the ion saturation current Iprobe monotonously de-
creases. For argon ion current is always higher, Uind is
always lower, and the range of effective ionization is
more then order higher at pressure scale.
3.3. LANGMUIR PROBE MEASUREMENTS
For measurement of local plasma parameters a Lang-
muir probe was used. The probe was placed on the cham-
ber axis approximately 2 cm higher the substrate holder.
Measuring of the probe traces and the probe data process-
ing was done using the “PLASMAMETER” device. All
the presented here results are measured with pure argon
feeding at RF power 200W.
Fig. 6 shows evolution of electron energy distribution
0 10 20 30 40 50 60
0
5
10
15
20
25
30
Argon
2.8·10-4
3.5·10-3
7·10-3
1.7·10-2
p = 3.3·10-2 Torr
8·10-2
1.7·10-1
2.7·10-1
j,
m
A
/c
m
2
R, mm
Fig. 2. Radial distributions of the ion current density to
the chamber bottom (P = 200W)
10-4 10-3 10-2 10-1 100
0
3
6
9
12
15
Ar
CF
4
N2
O
2
j,
m
A
/c
m
2
p, Torr
Fig. 4. Ion current to the wall probe vs. pressure for
different gases (P = 200W)
0 10 20 30 40 50 60
10-5
10-4
10-3
10-2
10-1
Electron energy, eV
EE
PF
, a
rb
. u
ni
ts
10
9
8
7
6
5
4
3
2
1
10
987
65
1) p = 5·10-2 Torr
2) p = 2·10-2 Torr
3) p = 1.3·10-2 Torr
4) p = 7·10-3 Torr
5) p = 4·10-3 Torr
6) p = 2·10-3 Torr
7) p = 1·10-3 Torr
8) p = 7·10-4 Torr
9) p = 5·10-4 Torr
10) p = 4·10-4 Torr
4
321
Fig. 6. Evolution of electron energy spectrum versus pres-
sure change
10-4 10-3 10-2 10-1
0
5
10
15
20
25
30
35
wall
probe
Collisonal
limit
Argon
bottom
probe
j,
m
A
/c
m
2
p, Torr
2-D fluid model
Global model
Collisonless
limit
Fig. 3. Ion current to the bottom and the side wall probes on
argon pressure in comparison with theoretical data
10-4 10-3 10-2 10-1 100
0.0
0.5
1.0
1.5
2.0
2.5
O2
N2
CF
4
Ar
U
in
d, k
V
p, Torr
Fig. 5. Inductive coil voltage vs. pressure for different
gases (P = 200W)
191
10-4 10-3 10-2 10-1 100
1010
1011
1012
1013
0
1
2
3
4
5
6
7
8
9
Global model
2-D fluid model
Ne
T
e
El
ec
tro
n
de
ns
ity
, c
m
-3
Argon pressure, Torr
E
le
ct
ro
n
te
m
pe
ra
tu
re
, e
V
Fig. 7. Electron density Ne and temperature Te in the
chamber center vs. argon pressure. Bold lines – experi-
mental results
with pressure change. On can see the monotonic decrease
of mean electron energy with the pressure growth. At
pressures below 2 mTorr the electron energy spectrum
became clearly two-temperature, at higher pressures it is
Maxwellian with damped tail, and at highest pressures it
have Druevestain-like shape.
Electron density Ne and temperature Te in the chamber
center vs. argon pressure are shown in Fig. 7. Experimen-
tal results presented with bold lines. As one can expect
from general gas discharge theory, we have monotonic
decrease of the electron temperature and increase of the
electron density with the pressure growth in the whole
researched pressure range.
4. COMPARISON TO THEORY
In Fig. 3 and 7 the described above experimental data
are shown in comparison to theoretic results. The well
known spatially averaged “Global” model [2] was used
as well as 2-D fluid model described in detail in [3]. Ob-
viously the Global model matches the experimental data
at low pressures (excluding the lowest pressures near the
discharge distinction where power loss grows in the in-
ductive coil decreasing the power absorbed by plasma),
whereas the fluid model is good for high pressures ac-
cording to the validity condition of the diffusive ap-
proach.
ACKNOWLEDGEMENT
This work was supported by Ministry of Industrial
Policy of Ukraine, Project 92373/60.
REFERENCES
1. J. Reece Roth. Industrial plasma engineering. Institute
of Physics Publishing, Bristol, UK, 2001.
2. M. A. Lieberman and A. J. Lichtenberg. Principles of
Plasma Discharges and Materials Processing. New York:
Wiley, 1994.
3. I.Denysenko, S.Dudin, A.Zykov, N.Azarenkov. Ion
flux uniformity in inductively coupled plasma sourses//
Physics of Plasmas. 2002, v.9, N11, p. 4767-4775.
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