Ta2O5 is a candidate for use in metal–oxide–metal (MOM) capacitors in several areas of silicon device technology. Understanding and controlling leakage current is critical for successful implementation of this material. We have studied thermal and photoconductive charge transport processes in Ta2O5 MOM capacitors fabricated by anodization, reactive sputtering, and chemical vapor deposition. We find that the results from each of these three methods are similar if one compares films that have the same thickness and electrodes. Two types of leakage current are identified: (a) a transient current that charges the bulk states of the films and (b) a steady state activated process involving electron transport via a defect band. The transient process involves either tunneling conductivity into states near the Fermi energy or ion motion. The steady state process, seen most commonly in films <300 Å thick, is dominated by a large number of defects, ∼1019–1020cm−3, located near the metal–oxide interfaces. The interior of thick Ta2O5 films has a substantially reduced number of defects. Modest heating (300–400 °C) of Ta2O5 in contact with a reactive metal electrode such as Al, Ti, or Ta results in interfacial reactions and the diffusion of defects across the thickness of the film. These experiments show that successful integration of Ta2O5 into semiconductor processing requires a better understanding of the impact of defects on the electrical characteristics and a better control of the metal–Ta2O5 interface.

1.
W. D. Westwood, N. Waterhouse, and P. S. Wilcox, Tantalum Thin Films (Academic, London, 1975).
2.
C.
Channeliere
,
J. L.
Autran
,
R. A. B.
Devine
, and
B.
Balland
,
Mater. Sci. Eng., R.
22
,
269
(
1998
).
3.
T. W.
Hickmott
,
J. Electrochem. Soc.
113
,
1223
(
1966
).
4.
J. H.
Thomas
,
Appl. Phys. Lett.
22
,
406
(
1973
).
5.
J. H.
Thomas
,
J. Appl. Phys.
45
,
5349
(
1974
).
6.
J. H.
Thomas
,
J. Appl. Phys.
45
,
835
(
1974
).
7.
M.
Hartl
,
Solid-State Electron.
12
,
1002
(
1960
).
8.
F. C.
Aris
and
T. J.
Lewis
,
J. Phys. D: Appl. Phys.
6
,
1067
(
1973
).
9.
D. A.
Vermilyea
,
J. Electrochem. Soc.
104
,
427
(
1957
).
10.
D. A.
Vermilyea
,
J. Electrochem. Soc.
104
,
485
(
1957
).
11.
G. A. N. Connell, in Amorphous Semiconductors, edited by M. H. Brodsky (Springer, New York, 1979), Vol. 36, pp. 71–111.
12.
W. H.
Knausenberger
and
R. N.
Tauber
,
J. Electrochem. Soc.
120
,
927
(
1973
).
13.
A. G.
Revesz
,
J. J.
Reynolds
, and
J. F.
Allison
,
J. Electrochem. Soc.
123
,
889
(
1976
).
14.
P. A.
Murawala
,
M.
Sawai
,
T.
Tatsuta
,
O.
Tsuji
,
S.
Fujita
, and
S.
Fujita
,
Jpn. J. Appl. Phys., Part 1
32
,
368
(
1993
).
15.
S. M. Sze, Physics of Semiconductor Devices, 2nd ed. (Wiley, New York, 1981).
16.
Y.
Pozdeev-Freeman
,
A.
Gladkikh
,
M.
Karpovski
, and
A.
Palevski
,
J. Electron. Mater.
27
,
1034
(
1998
).
17.
L. S.
Palatnik
,
Y. L.
Poszdeev
, and
V. V.
Starikov
,
Tech. Phys. Lett.
20
,
276
(
1994
).
18.
B. T.
Boiko
,
V. R.
Kopach
,
S. M.
Melentjev
,
P. A.
Pancheha
,
Y. L.
Pozdeev
, and
V. V.
Starikov
,
Thin Solid Films
229
,
207
(
1993
).
19.
G. A.
Thomas
,
M.
Capizzi
, and
F.
DeRosa
,
Philos. Mag. B
42
,
913
(
1980
).
20.
A. K.
Jonscher
,
J. Phys. D: Appl. Phys.
32
,
R57
(
1999
).
21.
M.
Schumacher
and
R.
Waser
,
Integr. Ferroelectr.
22
,
109
(
1998
).
22.
H.
Kliem
,
IEEE Trans. Electr. Insul.
24
,
185
(
1989
).
23.
Science and Technology of Electroceramic Thin Films, edited by O. Auciello and R. Waser (Kluwer, Dordrecht, 1994).
24.
M.
Schumacher
,
G. W.
Dietz
, and
R.
Waser
,
Integr. Ferroelectr.
10
,
231
(
1995
).
25.
Y.
Fukuda
,
K.
Aoki
,
K.
Numata
, and
A.
Nishmiura
,
Jpn. J. Appl. Phys., Part 1
33
,
5255
(
1994
).
26.
S. M.
Cho
and
D. Y.
Jeon
,
Thin Solid Films
338
,
149
(
1999
).
27.
T.
Kawahara
,
M.
Yamamuka
,
A.
Yuuki
, and
K.
Ono
,
Jpn. J. Appl. Phys., Part 1
34
,
5077
(
1995
).
28.
T.
Horikawa
,
T.
Makita
,
T.
Kuroiwa
, and
N.
Mikami
,
Jpn. J. Appl. Phys., Part 1
34
,
5478
(
1995
).
29.
T.
Mihara
,
H.
Watanabe
, and
C. A. P.
d. Araujo
,
Jpn. J. Appl. Phys., Part 1
33
,
5281
(
1994
).
30.
A.
de Polignac
and
M.
Jourdain
,
Thin Solid Films
71
,
189
(
1908
).
31.
H.
Adachi
and
Y.
Shibata
,
J. Phys. D: Appl. Phys.
8
,
1120
(
1975
).
32.
G. M.
Gusinskii
,
L. G.
Karpukhina
,
V. M.
Muzhdaba
,
V. O.
Naidenov
,
G. F.
Tomilenko
, and
S. D.
Khanin
,
Sov. Phys. Solid State
29
,
1867
(
1987
).
33.
M. J.
Duggan
,
T.
Saito
, and
T.
Niwa
,
Solid State Ionics
62
,
15
(
1993
).
34.
J.
Lee
,
S.
Esayan
,
J.
Prohaska
, and
A.
Safari
,
Mater. Res. Soc. Symp. Proc.
310
,
107
(
1993
).
35.
G. Martin and S. Markram-Ebeid, in Deep Centers in Semiconductors, edited by S. T. Pantelides (Gordon and Breach, Yverdon, Switzerland, 1992), pp. 457–546.
36.
M.
Brazier
,
S.
Mansour
, and
M.
McElfresh
,
Appl. Phys. Lett.
74
,
4032
(
1999
).
37.
J. A.
Davies
,
B.
Domeij
,
J. P. S.
Pringle
, and
F.
Brown
,
J. Electrochem. Soc.
112
,
675
(
1965
).
38.
A. R. West, Solid State Chemistry and its Applications (Wiley, New York, 1984).
39.
T.
Heiser
,
S.
McHugo
,
H.
Hiesimair
, and
E. R.
Weber
,
Appl. Phys. Lett.
70
,
3576
(
1997
).
40.
E. H.
Snow
,
A. S.
Grove
,
B. E.
Deal
, and
C. T.
Sah
,
J. Appl. Phys.
36
,
1664
(
1965
).
41.
J. P.
Chang
,
M. L.
Steigerwald
,
R. M.
Fleming
,
R. L.
Opila
, and
G. B.
Alers
,
Appl. Phys. Lett.
74
,
3705
(
1999
).
42.
H.
Sawada
and
K.
Kawakami
,
J. Appl. Phys.
86
,
956
(
1999
).
43.
S.
Makram-Ebeid
and
M.
Lannoo
,
Phys. Rev. B
25
,
6406
(
1982
).
44.
C. H.
Henry
and
D. V.
Lang
,
Phys. Rev. B
15
,
989
(
1977
).
45.
V. V.
Bryksin
and
D. D.
Khanin
,
Phys. Solid State
35
,
1126
(
1993
).
46.
V. V.
Bryksin
,
M. M.
D’yakonov
, and
S. D.
Khanin
,
Sov. Phys. Solid State
22
,
818
(
1980
).
47.
N. F. Mott, Metal-Insulator Transitions (Taylor & Francis, London, 1990).
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