scispace - formally typeset
Search or ask a question
Journal ArticleDOI

PE MOCVD of thin high transparent dielectric amorphous films of aluminium oxide

TL;DR: In this paper, thin transparent amorphous films of aluminum oxide have been obtained using PE MOCVD technique and aluminum β-diketonate as precursor in controlled mixture of gas reagents Ar and O 2.
Abstract: Thin transparent amorphous films of aluminum oxide have been obtained using PE MOCVD technique and aluminum β-diketonate as precursor in controlled mixture of gas reagents Ar and O 2 . The films were deposited on glass, quartz and stainless steel substrates at temperature range of 100-250°C. The correlation between electric properties and such deposition parameters as r.f. power Wp, the total gas pressure in chamber P o , O 2 partial pressure, the substrate temperature T, and gas carrier flow rate were determined. Optimal deposition conditions of Al 2 O 3 layers with high dielectric characteristics were established. Auger analysis showed that the composition of films obtained was stoichiometric. Auger depth profiles showed the existence of the transition area enriched with oxygen in the film/substrate heterostructure.

Summary (1 min read)

Jump to:  and [2. EXPERIMENTAL DETAILS]

2. EXPERIMENTAL DETAILS

  • Auger spectrometer "JAMP -10s" was used to determine chemical composition of the fiims.
  • Films' structures were examined with the help of diffractometer "DRON -3" and rotation chamber.
  • Optical transmission was measured using two beam spectrometers "Specord UV-WS" and "PYE-UNICAM-8800" with spectral range of 200 -800 nm and 190 -850 nm correspondingly.

Did you find this useful? Give us your feedback

Content maybe subject to copyright    Report

HAL Id: jpa-00253947
https://hal.archives-ouvertes.fr/jpa-00253947
Submitted on 1 Jan 1995
HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entic research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.
L’archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diusion de documents
scientiques de niveau recherche, publiés ou non,
émanant des établissements d’enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.
PE MOCVD of Thin High Transparent Dielectric
Amorphous Films of Aluminium Oxide
V. Ovsyannikov, G. Lashkaryov, E. Mazurenko
To cite this version:
V. Ovsyannikov, G. Lashkaryov, E. Mazurenko. PE MOCVD of Thin High Transparent Dielectric
Amorphous Films of Aluminium Oxide. Journal de Physique IV Proceedings, EDP Sciences, 1995, 05
(C5), pp.C5-705-C5-709. �10.1051/jphyscol:1995585�. �jpa-00253947�

JOURNAL
DE
PHYSIQUE
IV
Colloque
C5,
suppl6ment au Journal de Physique
LI,
Volume
5,
juin
1995
PE
MOCVD
of
Thin High Transparent Dielectric Amorphous Films
of
Aluminium Oxide
V.P. Ovsyannikov,
G.V.
Lashkaryov and
E.A.
Mazurenko*
Institute for Problems of Material Sciences of National Academy of Sciences of Ukraine,
3 Krzhizhanovskogo str., Kiev-180,
UA-252180, Ukraine
*
Institute of General and Inorganic Chemistry of National Academy of Sciences of Ukraine,
32/34
Palladina prosp., Kiev-142, UA-252142, Ukraine
Abstract. Thin transparent amorphous films of aluminum oxide have been obtained using
PE
MOCVD
technique
and aluminum
P-diketonate as precursor in controlled mixture of gas reagents
Ar
and
02.
The films were depos-
ited on glass, quartz and stainless steel substrates at temperature range of
100
--
250°C.
The correlation between
electric properties and such deposition parameters as
r.f. power Wp, the total gas pressure in chamber
Po,
O2
par-
tial pressure, the substrate temperature
T,
and gas carrier flow rate were deteri~uned. Optimal deposition conditions
of
A1203
layers with high dielectric characteristics were established.
Auger analysis showed that the composition of films obtained
was
stoichiometric. Auger depth profiles showed the
existence of the transition area enriched with oxygen in the
filmlsubstrate heterostructure.
1.
INTRODUCTION
Recently aluminum oxide films have become widely applied in different electronic devices
[1,2].
The main
functional characteristics of these films are higher than-those of dielectric usually used
[3,4].
h203
could
be obtained using various techniques;
r.f reactive and electron beam evaporations
[5,6,7],
MO CVD
[8],
LA
CVD
[9],
chemical and plasma oxidation of aluminum
[10,11],
anodization
[2],
thermal evaporation
[12],
plasma chemical deposition
[13],
etc.
PE
MOCVD
is one of the most promising for deposition of
functional layers on the structures with developed surface relief that does not allow high temperature effect
[2,61.
The quality and physical properties of deposited layers significantly depend on constructive peculiari-
ties of equipment used for deposition and technological parameters of deposition process
[14].
S&ce there
are insuperable mathematical difficulties the optimization of synthesis based on data about mechanism of
plasmachemical reactions is found to be difficult nowadays. So we have conducted the optimization pro-
ceeding from correlation between technological parameters and the main physical properties of the films.
In this paper we report on
A1203 films obtained by PE MOCVD technique using aluminum
P-
diketonate
&
as precursor. The object of our work was also to determine the technological parameters
which affect the chemical composition and physical properties of films obtained.
2.
EXPERIMENTAL DETAILS
Aluminum oxide films were deposited in tunnel plasma chemical reactor with capacitor excitation of
plasma discharge. Output power of generator and working frequency was
Wp=0.2
--
0.7
kW
and
13,s
MHz
correspondingly. The pumping system was equipped with a liquid nitrogen trap between the throttle
and the deposition chamber. Films deposition was carried out in the mixture of argon and oxygen
(Ar:02
was
1
:
1)
under the pressure of
P~0.2
--
1
Torr. Gas mixture composition was controlled using rotameters.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1995585

C5-706
JOURNAL
DE
PHYSIQUE
IV
Argon
used
as gas carrier passed through cylinder heater which contained precursors put into quartz
am-
poule with calibrated orifice. The control of precursor vapors flows ingress into deposition zone was
car-
ried out using ampoules with outlets of different diameters (from 0.2 to 1.2 pm), adjustment of gas carrier
flow (20
-
100
dmin)
and evaporation temperatures.
Coordination compound of Al(AAb was used as precursor.
Its
evaporation temperature equals to 155
-
1
60°C and temperature dependence of saturated vapor pressure as determined using derivatography and
gas chromatography
correspondiigly. Silicon, quartz,
glass
and stainless steel used
as
substrates were
heated
within
the temperature range of 100
-
250"
C.
Thermocouple insulated and screened from
RF
dis-
charge
was
used to control substrate temperature. Since the working chamber was rather large (300 mm
length, 200
rnm
diameter) it was necessary to convey
P
-diketonate vapors by quartz tube into the deposi-
tion zone to increase reagents concentrations near the substrate surface. The substrate was plasma chemi-
cally purified during 5 minutes in argon and oxygen atmospheres subsequently before the deposition
started (plasma discharge power was 700
W).
Auger spectrometer
"JAMP
-
10s" was used to determine chemical composition of the fiims. Films'
structures were examined with the help of
diffractometer
"DRON
-
3"
and rotation chamber. Optical
transmission was measured using two beam spectrometers
"Specord
UV-WS"
and "PYE-UNICAM-8800"
with spectral range of 200
-
800 nm and 190
-
850 nm correspondingly.
3.
RESULTS
AND
DISCUSSION
In
situ grown
Ah03
films were light-yellow due to carbon presence as evident from Auger spectrum stud-
ies (Fig. la). The carbon content in
film
was shown to be dependent on the tube length
L
of quartz injector
of precursor
(AI(AA)3)
and on gas carrier flow rate
Q,
that is on plasma discharge activation time. It was
determined that there are no carbon impurities in the
films obtained under different deposition conditions
when the tube used
was
more than
17
cm long (Figlb,2).
Figure
1:
Auger
spectra
of
aluminum
oxide
films
deposited at differ-
Figure
2:
Carbon content
in
aluminum
oxide
films
ent
length of injector
tube:
(a)
L=5
cm;
(b)
L=20
cm.
W800
W;
as
a
function
of
injector
tube
length
(according
to
+SO0
mlhnin.
Auger
spectra data).
Aluminum oxide films deposition process conditions
(W,
T,,
Q,
PO) were optimized for such qualita-
tive characteristics
as
film resistivity
p
and breakdown field
E.
Figure 3a shows the positive effect of tem-
perature increase on resistivity and breakdown field
values.
Taking into account the unaltered chemical
compositions of the films deposited under different temperatures we supposed that these temperature rela-
tionships depend on increase of structural order (degree) in the films
[12].
This process causes
p
and
E
de-
crease when gas carrier flow rate increases
(Fig.3b). Besides when
Q
>70 mumin the film fogging due to
carbon impurity's presence could be observed. When plasma discharge power increased resistivity of the

film
grew insignificantly. However, there was a pronounced decrease of the breakdown fields values
start-
ing from the value of
450
W
that was probably connected
with
film's porosity increase due to intensive
bombardment of growing layer by high energy plasma discharge components
(Fig.3~). This reason also
caused
E
decrease when chamber pressure during deposition process
was
low.
Fipre
3:
Resistivity and breakdown field dependence
versus:
(a)
substrate temperature
(Wp=400W,
Q=SOml/min,
P0=0.6 TOR);
(b)
gas
canier flow
rate
(Wp=350
W,
T.=~~o'c,
Pd.6
Torr);
(c)
chamber pressure
(Wp=350
W,
T,=230eC,
Q=50 mllmin);
(d)
r.f.powr
~1;=230"C, Q-50 mllmin,
Po=0.6
Tom).
ALL,
I
L
a
b
Fipre
4:
Possible fragmentation ways of aluminum p-diketonate
by
mass spectroscopic data
(L.
is P-diketone).
Resistivity and breakdown field values of films deposited under diierent oxygen partial pressures in
working chamber remained
almost unchanged. This fact could be explained by high probability of
fil(kA)~
dissociation proceeding by fragment channel where A-0 fragment
is
formed
[I61
(Fig.4).
As
a
conse-
quence there was an
unsuccessfU1 attempt of aluminum nitride
thin
film
deposition using ammonia
as
nitro-
gen precursor. Only aluminum oxynitride films with nitrogen content of
10-15
at.% and dielectric charac-
teristics slightly different
from those ones
of
A203
films have been deposited.

C5-708
JOURNAL
DE
PHYSIQUE IV
Since the optimization of deposition process based on main technological parameters effecting the
qualitative characteristics of aluminum oxide films was carried out only the films deposited under optimal
conditions have been examined. These high quality colorless dense fdms have smooth surface mor-
phology and good adhesion to the substrate as it was shown by the results of scratch method
[17].
Along
with
the values of resistivity
p
x1014 Ohm .cm and breakdown field
E
x
10' Vlcm some other
parameters have been determined for capacitor
MIM
structures. Leakage current density was 3
-
10
mA/cm2 under applied voltage of 50
V
(film thickness was 0,2
-
0,3 pm). The value of tg
6
for different
samples varied in the range of
0.001
-
0.005 when the
frequency
was
1
kHz
and the voltage was
15
V; di-
electric constant
E
has the value of 7.8
-
8.3.
Auger spectra showed the
stoichiometric composition of the films obtained. Auger spectroscopy also
has been used to study
A1203 film chemical composition as a hnction of film's thickness (Fig.5). Film's
composition was determined
from the relative intensities of Auger peaks when the film was etched layer by
layer in the chamber of Auger spectrometer using argon ions. Heterostructure profiles indicated the oxygen
content to increase
in
the film area close to the substrate that is in agreement with [lo].
*"m
,n,c.n.,r
n
,nn,
Figure
5:
Auger depth profiles of component distribution in heterostructure of A1203/Si
film
(h
is
film
thickness).
X-ray studies revealed the amorphous structure of the as-deposited films. However the analysis of de-
pendence of the
film
electric characteristics on the parameters of the deposition process shows the possibil-
ity of deposition of aluminum oxide layers with the resistivity and breakdown field magnitudes close to
those
in
crystalline films.
The transmission spectra of aluminum oxide films deposited on transparent substrates (quartz, glass)
have been studied. The transmission factor in the visible spectrum range was 85-95
%
when the film thick-
ness was 0.2
-
0.3
pm.
4.
CONCLUSIONS
Examination of how such deposition parameters as the substrate temperature, gas carrier flow rate, charn-
ber pressure and r.f. power effect on dielectric characteristics of the films obtained allowed to optimize
PE
MOCVD
process.
Amorphous high transparent aluminum oxide films of stoichiometric composition with suitable
dieleo
tric
properties
(p
-
1014 Ohrn.cm,
E
-
10' Vlcm) and good adhesion have been deposited at the tempera-
ture range of 200
-
250°C.
Auger profiles of chemical components through film thickness revealed the presence of oxygen en-
riched transition area in film
--
substrate heterostructure.
We suppose that plasma enhanced chemical vapor deposition of aluminum oxide thin films using alu-
minum
P-diketonate as precursor shows promise for dielectric layers deposition on the structures with de-
veloped relief that does not allow high temperature effect.

Citations
More filters
Journal ArticleDOI
TL;DR: In this paper, the authors have grown α-Al2O3 thin films directly on silicon at room temperature using pulsed laser deposition (PLD) and used them for gate insulation and low resistivity junction.

98 citations

Journal ArticleDOI
TL;DR: In this article, aluminum oxide thin films playing the role of the insulator were used to create metal-insulator-semiconductor (MIS) structures with aluminum oxide layers.
Abstract: This work presents results of investigations of Al2O3 thin films, deposited on Si substrates by means of impulse plasma deposition (IPD). Round, aluminum (Al) electrodes were evaporated on the top of deposited layers. Thus, metal-insulator-semiconductor (MIS) structures were created with aluminum oxide thin films playing the role of the insulator. It enabled subsequent electrical of studied material. Al2O3 layers were selective etched in a buffer of hydrofluoric acid. The photoresist was used as a masking material. The influence of etching time on the photoresist mask, etching progress, and the state of exposed Si surface was subsequently studied and is discussed. Films' microstructure were additionally studied by scanning electron microscopy (SEM).

21 citations