Oxygen activation effect on reactive magnetron synthesis of alumina coatings
The investigation results of the DC magnetron sputtering system for synthesis of high-quality oxide coatings are presented. In the system oxygen, activated by an independent Inductively-Coupled Plasma (ICP) source, is introduced into an aluminum sputtering chamber as an alternative to conventional r...
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| Zitieren: | Oxygen activation effect on reactive magnetron synthesis of alumina coatings / J. Walkowicz, A.V. Zykov, S.V. Dudin, S.D. Yakovin // Вопросы атомной науки и техники. — 2007. — № 1. — С. 194-196. — Бібліогр.: 5 назв. — англ. |
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Walkowicz, J. Zykov, A.V. Dudin, S.V. Yakovin, S.D. 2017-01-04T20:08:59Z 2017-01-04T20:08:59Z 2007 Oxygen activation effect on reactive magnetron synthesis of alumina coatings / J. Walkowicz, A.V. Zykov, S.V. Dudin, S.D. Yakovin // Вопросы атомной науки и техники. — 2007. — № 1. — С. 194-196. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS: 52.77.-j, 81.15.-z https://nasplib.isofts.kiev.ua/handle/123456789/110582 The investigation results of the DC magnetron sputtering system for synthesis of high-quality oxide coatings are presented. In the system oxygen, activated by an independent Inductively-Coupled Plasma (ICP) source, is introduced into an aluminum sputtering chamber as an alternative to conventional reactive sputtering techniques employing the injection of ground state molecular O₂. Characteristics of deposition behavior are investigated with and without the activation of the reactive species. Представлено результати досліджень магнетронної розпилювальної системи, що застосовується для синтезу високоякісних окисних покриттів. В робочу камеру кисень напускається вже попередньо активованим за допомогою високочастотного індукційного джерела, що є альтернативою звичайному реактивному магнетронному нанесенню, коли до робочої камери подається молекулярний кисень O₂. Досліджено характеристики процесу нанесення, як з попередньою активацією реактивного газу, так і без неї. Представлены результаты исследований магнетронной распылительной системы, используемой для синтеза высококачественных оксидных покрытий. В рабочую камеру кислород напускается уже предварительно активированный при помощи источника на базе высокочастотного индукционного разряда, что является альтернативой обычному реактивному магнетронному нанесению, когда в рабочую камеру напускается молекулярный кислород O₂. Исследованы характеристики процесса нанесения, как с предварительной активацией реактивного газа, так и без. The work was supported by COST 532 grant M 12 and Ministry of Education and Science of Ukraine (Project 0100U003301). en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Low temperature plasma and plasma technologies Oxygen activation effect on reactive magnetron synthesis of alumina coatings Вплив активації кисню на процес реактивного магнетронного синтезу покриттів з окису алюмінію Влияние активации кислорода на процесс реактивного магнетронного синтеза покрытий оксида алюминия Article published earlier |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Oxygen activation effect on reactive magnetron synthesis of alumina coatings |
| spellingShingle |
Oxygen activation effect on reactive magnetron synthesis of alumina coatings Walkowicz, J. Zykov, A.V. Dudin, S.V. Yakovin, S.D. Low temperature plasma and plasma technologies |
| title_short |
Oxygen activation effect on reactive magnetron synthesis of alumina coatings |
| title_full |
Oxygen activation effect on reactive magnetron synthesis of alumina coatings |
| title_fullStr |
Oxygen activation effect on reactive magnetron synthesis of alumina coatings |
| title_full_unstemmed |
Oxygen activation effect on reactive magnetron synthesis of alumina coatings |
| title_sort |
oxygen activation effect on reactive magnetron synthesis of alumina coatings |
| author |
Walkowicz, J. Zykov, A.V. Dudin, S.V. Yakovin, S.D. |
| author_facet |
Walkowicz, J. Zykov, A.V. Dudin, S.V. Yakovin, S.D. |
| topic |
Low temperature plasma and plasma technologies |
| topic_facet |
Low temperature plasma and plasma technologies |
| publishDate |
2007 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Вплив активації кисню на процес реактивного магнетронного синтезу покриттів з окису алюмінію Влияние активации кислорода на процесс реактивного магнетронного синтеза покрытий оксида алюминия |
| description |
The investigation results of the DC magnetron sputtering system for synthesis of high-quality oxide coatings are presented. In the system oxygen, activated by an independent Inductively-Coupled Plasma (ICP) source, is introduced into an aluminum sputtering chamber as an alternative to conventional reactive sputtering techniques employing the injection of ground state molecular O₂. Characteristics of deposition behavior are investigated with and without the activation of the reactive species.
Представлено результати досліджень магнетронної розпилювальної системи, що застосовується для синтезу високоякісних окисних покриттів. В робочу камеру кисень напускається вже попередньо активованим за допомогою високочастотного індукційного джерела, що є альтернативою звичайному реактивному магнетронному нанесенню, коли до робочої камери подається молекулярний кисень O₂. Досліджено характеристики процесу нанесення, як з попередньою активацією реактивного газу, так і без неї.
Представлены результаты исследований магнетронной распылительной системы, используемой для синтеза высококачественных оксидных покрытий. В рабочую камеру кислород напускается уже предварительно активированный при помощи источника на базе высокочастотного индукционного разряда, что является альтернативой обычному реактивному магнетронному нанесению, когда в рабочую камеру напускается молекулярный кислород O₂. Исследованы характеристики процесса нанесения, как с предварительной активацией реактивного газа, так и без.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/110582 |
| citation_txt |
Oxygen activation effect on reactive magnetron synthesis of alumina coatings / J. Walkowicz, A.V. Zykov, S.V. Dudin, S.D. Yakovin // Вопросы атомной науки и техники. — 2007. — № 1. — С. 194-196. — Бібліогр.: 5 назв. — англ. |
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2025-11-26T00:08:22Z |
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| fulltext |
194 Problems of Atomic Science and Technology. 2007, 1. Series: Plasma Physics (13), p. 194-196
OXYGEN ACTIVATION EFFECT ON REACTIVE MAGNETRON
SYNTHESIS OF ALUMINA COATINGS
J. Walkowicz 1, A.V. Zykov2, S.V. Dudin 2, S.D. Yakovin 2
1Institute for Sustainable Technologies, Pulaskiego Str. 6/10, 26-600, Radom, Poland;
2V.N. Karazin Kharkov National University, Department of Physical Technologies,
Kurchatov av. 31, 61108 Kharkov, Ukraine
The investigation results of the DC magnetron sputtering system for synthesis of high-quality oxide coatings are
presented. In the system oxygen, activated by an independent Inductively-Coupled Plasma (ICP) source, is introduced
into an aluminum sputtering chamber as an alternative to conventional reactive sputtering techniques employing the
injection of ground state molecular O2. Characteristics of deposition behavior are investigated with and without the
activation of the reactive species.
PACS: 52.77.-j, 81.15.-z
1. INTRODUCTION
Aluminum oxide thin films are widely used in many
mechanical, optical and microelectronic applications be-
cause of their excellent properties, in terms of chemical
inertness, mechanical strength and hardness, transparency,
high abrasive and corrosion resistance, as well as insulat-
ing and optical properties. At present thin alumina coat-
ings (less then or about 1 micron) are used in production
of solar sells, elements for integral optics, diffusion bar-
rier applications and in microelectronics [1].
However, despite the obvious virtues of alumina coat-
ings, process of introduction of such coatings to the in-
dustry is in an initial stage, and scope of their use is far
from the same of TiN coatings. Direct current planar
magnetrons are widely used for deposition of metal coat-
ings [2]. At the same time ion-plasma synthesis of dielec-
tric coatings, in particular the oxides such as TiO2, Al2O3,
Ta2O5 etc. by DC magnetrons has got some serious diffi-
culties for the simple reason that the films being proc-
essed do not conduct current. This leads to the target pas-
sivation, intensive arcing, and the instability of discharge
(phenomenon of “disappearing anode”), that essentially
constricts the “window” of technological parameters and
reduces the coatings quality. One of traditional solutions
of these problems is the use of high-frequency or pulsed
power source. However in this case the deposition rate
falls and the equipment cost is essentially increased.
Reactive sputtering from a metallic target is the pre-
ferred choice for high rate deposition, but here the control-
lability issues of target and anode oxidation must be ad-
dressed. Because of these issues, the search continues for a
solution providing high throughput, reproducible reactive
sputtering results for materials like aluminum oxide.
In this paper the results of development of the DC
magnetron sputtering system for synthesis of high-quality
oxide coatings are presented. The basic idea of the system
consists in separation of 2 processes: metal target sputter-
ing by DC magnetron discharge in inert gas and activation
and transport of reactive gas by additional plasma source
based on RF inductive discharge [3].
2. EXPERIMENTAL SETUP
Film depositions were performed in a Balzers
BA-510A high vacuum pumping system with the base
pressure about 10-5 mbar. A schematic layout of the
magnetron and ICP source in the sputtering chamber is
shown in Fig. 1. A pure aluminum target of 170 mm
diameter mounted on magnetron 1 served as a sputtered
aluminum source. Power to the sputter cathode was
applied using 10 kW dc power supply 2, produced by
ITeE, operated in current or voltage regulation mode.
Current regulation was chosen in these experiments
simply as a monitor of process stability. By allowing the
cathode voltage to drift, the level of poisoning could
easily be monitored by tracking the target voltage [4,5].
Argon used as the sputtering gas in all deposition ex-
periments was fed to the chamber independently of the
reactive oxygen – through the dedicated manifold – di-
rectly on the magnetron target. Flows for both argon and
oxygen were regulated using BETA ERG mass flow con-
trollers operated by two-channel process control unit.
Pressure monitoring in the sputter chamber was accom-
plished using Balzers PKR-250 Pirani/Cold Cathode
gauge 8.
2
1
2
3
4
5
6
7
8
Ar
to vacuum
pump
10 cm
Fig.1. A schematic diagram of the alumina deposition
system: 1 - magnetron, 2 - DC power supply, 3 - ICP
source, 4 - RF matchbox, 5 - RF power supply, 6 - substrate
holder, 7 - substrate shield, 8 - vacuum gauge
195
Oxygen for the reactive sputtering was delivered
through the ICP source 3 for all deposition processes. A
ceramic tube 100 mm in diameter and 120 mm in length
was used as ICP source chamber. The source was located
10 cm closer to samples than the magnetron such that the
ICP source did not block the path of sputtered aluminum
(see Fig. 1). The substrates were mounted at shielded sub-
strate holder 6 that allows to deposit up to 12 samples per
pumping cycle.
3. TECHNOLOGY OF ALUMINA SYNTHESIS
USING THE ICP ENHANCED REACTIVE
MAGNETRON SPUTTERING SYSTEM
The key novelty of the present system comparing to
known designs is the operation pressure range
(0.7-3.5)·10-3 mbar where motion of particles may be
treated as free fall. It allows increasing the distance mag-
netron – substrate holder up to 30 - 40 cm, significant
increase in the deposition area with acceptable deposition
rate.
In Fig. 2 magnetron voltage-current characteristics are
presented at various oxygen flows. Measurements were
done in the following sequence. At high discharge current
(8 ) oxygen feeding was carried out up to the necessary
flow rate, and then the magnetron current was reduced
down to the passivated mode transition. The dependence
of minimum DC power of the magnetron operation in
metallic mode has been in such a way measured versus
oxygen flow rate (Fig. 3). Apparently from the figure it is
practically linear with the slope of about 10-12 sccm/kW.
To achieve a stable environment for aluminum oxide
deposition and to provide control margin to the reactive
deposition process, the effective oxygen partial pressure
at the substrate was modified using the preactivation of
the reactive gas using the independent RF ICP source.
The idea of this technique is to deliver gas of improved
reactivity to the substrate, further-increasing the effective
oxygen partial pressure in the deposition zone and thereby
increasing the operating margin by maintaining the target
in a more stable range on the hysteresis curve. This idea
was successfully verified in our experiments.
The standard sequence of the deposition process
stages used in the present experiments is described below,
the choice of technological regime for stoichiometric
alumina deposition was done with the help of diagrams
given in Figs. 2, 3.
Question of principle at deposition of stoichiometric
Al2O3 films when using the directed source of activated
oxygen is the relative positioning of the magnetron, the
plasma source and the substrate. It has been established,
that alongside with main technological process parameters
(magnetron and RF discharge power, oxygen flow rate,
argon pressure), the geometrical parameters (distances
and angles of the magnetron and the plasma source in
relation to the substrate holder) determine 3-dimensional
Al2O3 stoichiometrical region in the chamber space.
In the Fig. 4 a typical 2D stoichiometrical diagram of
the films synthesized in the present system is shown in
the plane passing trough the axis of the magnetron and
ICP source.
3.1. TECHNOLOGICAL BASELINE
1. The substrates (glass, clear an TiN coated high-speed
steel SW7M) cleaned in ultrasonic bath with standard
technology, were mounted on a shielded substrate holder
allowing multiple sample deposition per pumping cycle.
Processing started after pumping to the base pressure
10-5 mbar or less.
0
100
200
300
400
500
600
0 2 4 6 8
Oxygen flow rate, sccm
2
1
30209.5
U
, V
I, A
Fig. 2. Current-voltage characteristics of the magne-
tron:1 – Ar at 0.8 mTorr, 2 – O2 at 0.8 mTorr
3
10 cm
1
2
Fig.4. 1 - magnetron, 2 - ICP source, 3 - substrate
holder with film transparency distribution shown.
Stoichiometrical region is hatched
0 5 10 15 20 25 30 35 40
0
1
2
3
4
5
6
target arcing threshold
target poisoning threshold
P,
k
W
Q, sccm
Fig. 3. Dependence of minimum magnetron DC power P
for metallic mode operation on oxygen flow rate Q
196
2. The substrates were cleaned and activated in Ar ICP
discharge at pressure (1 - 3)·10-3 mbar and RF power
500 W during 5-15 min. DC bias (0, -100, -500, -1000 V)
was applied to the substrates, and substrate current was
measured.
3. After the cleaning stage the substrate bias was
switched off, the ICP discharge remained on, shield was
closed, and the magnetron was ignited at constant argon
pressure. After the oxidized magnetron target surface re-
covery to metallic mode and stabilization of the magne-
tron discharge parameters within 3-5 minutes, oxygen was
filled through ICP source. Oxygen flow rate was set ac-
cording to the diagram in Fig. 3. After that fine tuning of
the ICP source matchbox was performed if needed.
4. The shield was opened, and deposition time counting
was started. During the deposition process the RF
matchbox was tuned if reflected power exceed 10% of the
forward power. The magnetron power supply operated in
the current regulation mode, so no adjustment was neces-
sary.
5. After the deposition time termination the shield was
closed, oxygen flow was shut down, the magnetron power
supply and the RF generator were switched off, after that
delivery of argon was stopped and the chamber was
opened.
Process of aluminum film deposition was performed in
the same sequence, but without oxygen feeding.
4. CONCLUSIONS
To produce a fully oxidized aluminum oxide film and
reliably avoid target poisoning in a dc magnetron reactive
sputtering process one of two approaches must be taken:
1) to employ sophisticated feedback and control loops in
the gas delivery system to maintain the oxygen partial
pressure at a precisely specified level or 2) to use directed
source of activated oxygen such that the oxygen partial
pressure at the target is measurably less than that required
to cause poisoning but the partial pressure and reactivity
at the substrate is adequate to produce the films of the
desired properties. The technique, explored in this study,
was shown effective in producing high quality aluminum
oxide films in a dc reactive sputtering environment with-
out the issue of target poisoning. Using these enhance-
ments, films deposited in the flat portion of the target
voltage hysteresis curve displayed properties comparable,
and in some cases, superior to those deposited near the
knee of the curve without the aid of the mentioned en-
hancements.
The complex application of these solutions in the sput-
tering system has allowed to expand the range of stable
system operation: working pressure – (2-10)·10-4Torr,
magnetron discharge power – (1–8) kW, power of chemi-
cally active particles source – up to 1 kW, coating deposi-
tion rate (for example Al2O3) – up to 8 microns/hour, and
to improve essentially the coatings quality.
The work was supported by COST 532 grant M 12
and Ministry of Education and Science of Ukraine (Pro-
ject 0100U003301).
REFERENCES
1. E. Dorre, H. Hubner (Eds.) Alumina: Processing Prop-
erties and Applications. Berlin: “Springer”, 1984.
2. B.S. Danilin. The use of low-temperature plasma for
thin film deposition. M.: ”Energoatomizdat”, 1989.
3. I. Denysenko, S. Dudin, A. Zykov, N. Azarenkov. Ion
flux uniformity in inductively coupled plasma sources//
Phys. Plasmas. 2002, v. 9, N 11, p.4767.
4. A.V. Zykov, S.V. Dudin, S.D. Yakovin, J. Walkowicz.
Magnetron sputtering system for synthesis dielectric coat-
ings // 10th Int. Conf. on Plasma Physics and Controlled
Fusion, Alushta, Ukraine, September 13-18, 2004/ Book
of Abstracts, 2004, p.170.
5. M.I. Borodin, S.V. Dudin, V.I. Farenik. Time resolved
investigation of non-stationary magnetron discharge// 10th
Intl. Conf. on Plasma Physics and Controlled Fusion,
Alushta, Ukraine, September 13-18, 2004/ Book of Ab-
stracts, 2004, p.181.
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