Modernized technological accelerator with anode layer for ion cleaning
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2002 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2002
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Modernized technological accelerator with anode layer for ion cleaning / A.N. Dobrovol`s`kii, A.A. Goncharov, S.N. Pavlov, O.A. Panchenko, I.M. Protsenko // Вопросы атомной науки и техники. — 2002. — № 4. — С. 176-178. — Бібліогр.: 5 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859719093409546240 |
|---|---|
| author | Dobrovol`s`kii, A.N. Goncharov, A.A. Pavlov, S.N. Panchenko, O.A. Protsenko, I.M. |
| author_facet | Dobrovol`s`kii, A.N. Goncharov, A.A. Pavlov, S.N. Panchenko, O.A. Protsenko, I.M. |
| citation_txt | Modernized technological accelerator with anode layer for ion cleaning / A.N. Dobrovol`s`kii, A.A. Goncharov, S.N. Pavlov, O.A. Panchenko, I.M. Protsenko // Вопросы атомной науки и техники. — 2002. — № 4. — С. 176-178. — Бібліогр.: 5 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| first_indexed | 2025-12-01T08:33:10Z |
| format | Article |
| fulltext |
MODERNIZED TECHNOLOGICAL ACCELERATOR WITH ANODE
LAYER FOR ION CLEANING
Dobrovol`s`kii A.N., Goncharov A.A., Pavlov S.N. *, Panchenko O.A., Protsenko I.M.
Institute of Physics NAS Ukraine, Kiev
*Institute for Nuclear Researches NAS Ukraine, Kiev
PACS: 52.77.Bn
INTRODUCTION
At present time the technology for new functional
coatings possessing complex composition and layered
structure is developed intensively. Usually for that
purpose plasma sputtering sources of magnetron, vacuum
arc, electron beam and other types [1] are used. Quality of
the coating essentially depends on preliminary preparation
of the surface – its cleaning and activation. This treatment
should be done immediately before deposition of the
coating in the single technological cycle. In
microelectronics this task is usually solved by means of
Kaufmann source use [2]. However, this type of the
source has incandescent cathode in it, which limits its
technological abilities.
Another possibility consists in the use of plasma
accelerators with confined electron drift (for example,
accelerator with anode layer, AAL). These systems allow
obtaining the beams of ions of various substances with
energy ranging from tens electron-volts up to several
kiloelectron-volts and different densities (from
milliamperes up to several amperes). Simplicity and
reliability of the design, and also operational
characteristics extend possible use of AAL for various
applications [3].
In spite of external attractiveness of the system,
accelerators with anode layer were previously used mostly
as ion injectors and electric propulsions. Their abilities, as
the tools for surface cleaning and activation, were
described very incompletely [2]. On the other side, their
application in the single technological cycle, particularly,
in combination with continuously operating magnetron,
imposes a number of extra requirements for AAL.
We have developed and tested compact technological
accelerator with confined electron drift in crossed ExH
fields, as the tool for substrate cleaning and activation
immediately before deposition of functional coatings [4].
It has been shown that the device provides surface
cleaning rate at a level of ~ 1 nm/s, which is close to the
best values for Kaufmann source [2]. Special attention
was paid to compatibility of the accelerator by pressure of
working gases with magnetron operation. This problem
was solved by the use of gas supply immediately in
vacuum volume instead of common scheme of the supply
through the system electrodes. At the expense of that we
succeeded in raising operation pressure up to ~ 10-3 Torr.
It enables placement of the accelerator in the same
vacuum chamber with magnetron and their simultaneous
use, thus making possible creation of continuously
operating technological couples, which is especially
important for treatment of the surfaces with large square.
The present proceeding is devoted to optimization of
the accelerator design with an aims of increasing etching
rate and lowering operation voltages. The reasons leading
to non-monotonous dependence of etching rate on
pressure in the system are studied experimentally.
EXPERIMENTAL SETUP
The experiments were carried out with ring accelerator
with anode layer, similarly to those described in [4]. In
that work also description of the setup is given. Argon and
its mixtures with nitrogen and oxygen were used as
working gases.
In experiments performed earlier in [4] it was shown
that it is reasonable to supply working gas not through
accelerator cathode or anode (classic option), but
immediately to vacuum chamber. At that cleaning rate
grows up approximately twice, and working pressure
shifts toward higher values. That’s why exactly this
system of gas supply was used in modernized
configuration of the accelerator.
In initial experiments [4] wide polepieces were used for
the accelerator. In that case anode was situated in
practically uniform magnetic field with about
1000 Oersted strength. At the same time it is known [3,5]
that at AAL use for the propulsion it is recommended to
place the anode in region with increasing magnetic field.
The anode itself is elaborated at that, as hollow electrode.
In present work we checked, whether these
recommendations are valid at AAL use for ion cleaning.
For that purpose polepieces were narrowed down to
5 mm. The field strength in the gap remained practically
unchanged (1100 Oe), and at anode surface it decreased
down to 600 Oe.
Initially we used plane anode. Dielectric target (usually
glass) was placed at 7 cm distance from the accelerator.
For determining the surface cleaning rate photometry
method described in [4] was used.
176 Problems of Atomic Science and Technology. 2002. № 4. Series: Plasma Physics (7). P. 176-178
RESULTS OF MEASUREMENTS
Fig.1 exhibits dependencies of the target surface cleaning
rate on pressure in working volume at constant voltage on
the anode. Curves 1 and 1' correspond to uniform
magnetic field in the accelerator gap. Dependencies 2 and
2' are taken when the anode is in region of increasing
magnetic field. One can see that the curves are bell-
shaped and reach their maxima at pressures about 8-9⋅
10-4 Torr. At pressure decrease cleaning rate diminishes
quickly, however, it retains positive values right down to
zero. At pressure higher than 10-3 Torr cleaning is
replaced by deposition. It is easy to see that the new
magnetic field configuration provides higher values of the
surface cleaning rate. At the anode voltage of 1200 V this
increase is not critical, although it is visible. At 900 V
voltage observed growth of cleaning rates exceeds factor
of two. This fact is very remarkable from technological
viewpoint. Whereas earlier the voltage increase from 900
to 1200 V resulted in more than triple increase of cleaning
rate, now this difference became essentially smaller. It
justifies the use of voltages in accelerator less than
1000 V, which surely influences its operational
characteristics.
Plasma column with practically unchanged cross sec-
tion propagated from the accelerator for the distance not
less than 50 cm. In the column cross section cylindrical
zone situated under the anode (about 5 mm width) oc-
curred, inside of which cleaning rate reached maximum
and was almost homogeneous. Outside that ring zone
cleaning rate decreased sharply, however, it retained posi-
tive sign (that is, was not replaced by deposition). Thus,
cleaning profile was close to step-shaped one.
Use of hollow anode instead of plane one resulted in
formation of the plasma flux with crossover. However,
etching rate decreased at that, and edges of cleaning zone
became essentially fuzzy, which is undesirable from
technological viewpoint. It served as a base for the
conclusion that hollow anode use is unreasonable at AAL
use for technological applications.
For determining ion beam current onto the surface,
metal collector separated from the plasma by grid under
floating potential was installed in place of glass target.
Negative potential of 200-400 V value, at which ion
current reached saturation, was applied to the collector.
Dependencies of the ion beam current on pressure are
presented in Fig.2. As well as in case of uniform magnetic
field, the curves represent monotonously growing
characteristics. The ion beam current comprises about
10% of the discharge current.
For determining the reasons of etching rate decrease
the target potential was measured under the beam (Fig.3).
One can see that exactly in region of etching rate decrease
177
Fig. 1. Dependencies of the cleaning rate on pressure.
Curves 1 and 1' correspond to uniform magnetic field in
the accelerator gap. Dependencies 2 and 2' correspond
to anode is in region of increasing magnetic field.
Fig. 3. The floating target potential under the beam on dielectric.
Fig. 2. Dependencies of the ion beam current and
current density on pressure.
the target potential sharply increases. Measurements
accomplished by means of multi-grid analyzer have shown
that energy of ions coming out of the anode layer is
typical for the sources of such kind [3]. In this case
floating potential growth from 300 to 600 V (see Fig.3)
will strongly retard the ions, however, the portion of those
will still retain energy sufficient for sputtering the target
atoms.
One can mention ion-plasma flux defocusing in high
pressure range, as one more factor, leading to the decrease
of cleaning rate. The beam profiles measured at pressures
of 7⋅10-4 and 2⋅10-3 Torr are shown in Fig.4. It is easy to
see that the beam defocusing really takes place. However,
use of the compensator at the second pressure value
practically completely restores the flux profile (Fig.4). In
other words, the beam defocusing is a consequence of the
target floating potential change.
In consideration of the problem regarding AAL
compatibility with magnetron one should take into
account one more factor. In a process of depositing
complex coatings multi-component gas mixtures are often
used as plasma generating media. Most often in those
cases small (~ 10%) addings of nitrogen or oxygen are
used. That’s why we tested the influence of such addings
on the target cleaning rate. The experiments have shown
that nitrogen adding to argon does not provide essential
influence on the accelerator operation at nitrogen partial
pressure up to 30%. Adding the same quantity of oxygen
may lead to essential cleaning rate decrease (up to 3
times). The most probable reason of mentioned decrease
of the rate may consist in formation of copper oxides at
the surface to be cleaned.
CONCLUSIONS
Thus, in the proceeding it is shown that at use of
single-step accelerator with anode layer for surface
cleaning:
1 It is reasonable to place the anode in a region
with rising up magnetic field. In this case cleaning rate
increases, and usage of low voltages in the accelerator
power supply system becomes much more efficient.
2 Unlike the case of AAL use for propulsion, in
studied case the use of hollow anode is unreasonable
and leads to both decrease of cleaning rate, and spread
of the beam profile.
3 The beam defocusing observed at high pressures is a
consequence of the target floating potential growth and
resulted changes of ion-optical parameters of the
system.
4 Nitrogen adding (up to 30%) to plasma generating
gas does not provide significant changes in the
accelerator operation. However, adding of similar
amount of oxygen may lead to essential (up to 3 times)
decrease of cleaning rate.
ACKNOWLEDGMENTS
The present work was supported in part by STCU
grant #1596.
REFERENCES
1 Danilin B.S. Use of low-temperature plasma for
deposition of thin films. Moscow, Energoatomizdat,
1989 (in Russian).
2 Danilin B.S., Kireev V.Yu. Application of low-
temperature plasma for etching and cleaning of
materials. Moscow, Energoatomizdat, 1987, 263
pages (in Russian).
3 E.A.Lyapin, A.V.Semenkin. Modern state of
researches of the accelerators with anode layer. In
book “Ion injectors and plasma accelerators” edited
by A.I.Morozov and N.N.Semashko, Moscow,
Energoatomizdat, 1990, pp. 20-33 (in Russian).
4 A.A. Goncharov, A.M. Dobrovol`s`kii, O.A. Pan-
chenko, S.N. Pavlov, I.M. Protsenko Technological
accelerator with closed electron drift for surface
treatment. Problems of Atomic Science and
Technology, #6, Series: Plasma Physics (6), 2000, pp.
160-162
178
Fig. 4. The beam profiles at different pressures, with and without compensation. Ud = 900 V, Ar.
5 V.V.Egorov, V.Kim, A.A.Semenov, I.I.Shkarban
Near-wall processes and their influence on operation
of accelerators with confined electron drift. In book
“Ion injectors and plasma accelerators” edited by
A.I.Morozov and N.N.Semashko, Moscow,
Energoatomizdat, 1990, pp. 56-68 (in Russian).
179
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| id | nasplib_isofts_kiev_ua-123456789-80294 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-01T08:33:10Z |
| publishDate | 2002 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Dobrovol`s`kii, A.N. Goncharov, A.A. Pavlov, S.N. Panchenko, O.A. Protsenko, I.M. 2015-04-14T17:11:46Z 2015-04-14T17:11:46Z 2002 Modernized technological accelerator with anode layer for ion cleaning / A.N. Dobrovol`s`kii, A.A. Goncharov, S.N. Pavlov, O.A. Panchenko, I.M. Protsenko // Вопросы атомной науки и техники. — 2002. — № 4. — С. 176-178. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS: 52.77.Bn https://nasplib.isofts.kiev.ua/handle/123456789/80294 The present work was supported in part by STCU grant #1596. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Low temperature plasma and plasma technologies Modernized technological accelerator with anode layer for ion cleaning Article published earlier |
| spellingShingle | Modernized technological accelerator with anode layer for ion cleaning Dobrovol`s`kii, A.N. Goncharov, A.A. Pavlov, S.N. Panchenko, O.A. Protsenko, I.M. Low temperature plasma and plasma technologies |
| title | Modernized technological accelerator with anode layer for ion cleaning |
| title_full | Modernized technological accelerator with anode layer for ion cleaning |
| title_fullStr | Modernized technological accelerator with anode layer for ion cleaning |
| title_full_unstemmed | Modernized technological accelerator with anode layer for ion cleaning |
| title_short | Modernized technological accelerator with anode layer for ion cleaning |
| title_sort | modernized technological accelerator with anode layer for ion cleaning |
| topic | Low temperature plasma and plasma technologies |
| topic_facet | Low temperature plasma and plasma technologies |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/80294 |
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