We have applied a combinatorial technique to fabricate work function (WF) tuned Pt-W alloy films and used the films as metal electrodes for HfO2SiO2Si capacitors. As the ratio, RPt, of Pt to W changes from 0 to 1, the WF value varies continuously from 4.7 to 5.5 eV. This tunability enables us to systematically investigate the effect of WF variation on electrical properties. After a forming gas annealing process, the values of flatband voltage (Vfb) from capacitance-voltage properties are almost constant, regardless of the WF variation, because of oxygen vacancy formation that results in Fermi level pinning. On additional oxidizing gas annealing (OGA), the effect of WF value on Vfb becomes dominant. However, the difference in Vfb between W and Pt is 0.34 V, which is much smaller than the observed WF difference of 0.8 eV. We attribute this phenomenon to the lowering of the effective WF due to an electric dipole, induced by oxygen vacancy formation at the metal/HfO2 interface. Moreover, a decrease in Vfb in W-rich regions was observed following the OGA, suggesting the formation of a W-O bond at the interface. These results clearly indicate that the control of bonding states at the metal/HfO2 interfaces on an atomic scale is essential for the realization of a combination of metal and high-k dielectric films in future complementary metal-oxide-semiconductor devices.

1.
G. D.
Wilk
and
R. M.
Wallace
,
Appl. Phys. Lett.
74
,
2854
(
1999
).
3.
J.
Tersoff
,
Phys. Rev. Lett.
52
,
465
(
1984
).
4.
C.
Hobbs
,
L.
Fonseca
,
V.
Dhandapani
,
S.
Samavedam
,
B.
Taylor
,
J.
Grant
,
L.
Dip
,
D.
Triyoso
,
R.
Hedge
,
D.
Gilmer
,
R.
Garcia
,
D.
Roan
,
L.
Lovejoy
,
R.
Rai
,
L.
Hebert
,
H.
Tseng
,
B.
White
, and
P.
Tobin
,
2003 Symposium on VLSI Tech Digest
(
2003
).
5.
M.
Koyama
,
A.
Kaneko
,
T.
Ino
,
M.
Koike
,
Y.
Kamata
,
R.
Iijima
,
Y.
Kamimuta
,
A.
Takashima
,
M.
Suzuki
,
C.
Hongo
,
S.
Inumiya
,
M.
Takayanagi
, and
A.
Nishiyama
,
Tech. Digest 2002 IEEE Int. Electron Devices Meeting
, San Francisco,
2002
, p.
849
.
6.
K.
Shiraishi
,
K.
Yamada
,
K.
Torii
,
Y.
Akasaka
,
K.
Nakajima
,
M.
Konno
,
T.
Chikyow
,
H.
Kitajima
, and
T.
Arikado
, Tech. Digest.
2004 Symposium VLSI Technology
, Honolulu,
2004
), p.
108
.
7.
K.
Shiraishi
,
K.
Yamada
,
K.
Torii
,
Y.
Akasaka
,
K.
Nakajima
,
M.
Konno
,
T.
Chikyow
,
H.
Kitajima
, and
T.
Arikado
,
J. Appl. Phys.
43
,
L1413
(
2004
).
8.
P.
Ahmet
,
Y. -Z.
Yoo
,
K.
Hasegawa
,
H.
Koinuma
, and
T.
Chikyow
,
Appl. Phys. A: Mater. Sci. Process.
79
,
837
(
2004
).
9.
T.
Nagata
,
P.
Ahmet
,
Y. Z.
Yoo
,
K.
Yamada
,
K.
Tsutsui
,
Y.
Wada
, and
T.
Chikyow
,
Appl. Surf. Sci.
252
,
2503
(
2006
).
10.
J. R.
Hauser
and
K.
Ahmed
, Characterization and Metrology for ULSI Technology, p.
235
(International Conference, AIP, New York,
1998
).
11.
S.
Yamamoto
,
K.
Susa
, and
U.
Kawabe
,
J. Chem. Phys.
60
,
4076
(
1974
).
12.
I. A.
Weerasekera
,
S.
Ismat Shah
,
D. V.
Baxter
, and
K. M.
Unruh
,
Appl. Phys. Lett.
64
,
3231
(
1994
).
13.
Y. G.
Shen
,
Y. W.
Mai
,
Q. C.
Zhang
,
D. R.
McKenzie
,
W. D.
McFall
, and
W. E.
McBridge
,
J. Appl. Phys.
87
,
177
(
2000
).
14.
H. P.
Nielsen
,
Trans. Am. Inst. Min., Metall. Pet. Eng.
180
,
603
(
1949
).
15.
J.
Robertson
,
J. Vac. Sci. Technol. B
18
,
1785
(
2000
).
16.
A.
Kloss
,
T.
Motzke
,
R.
Grossjohann
, and
H.
Hess
,
Phys. Rev. E
54
,
5851
(
1996
).
17.
K.
Shiraishi
,
Y.
Akasaka
,
S.
Miyazaki
,
T.
Nakayama
,
T.
Nakaoka
,
G.
Nakamura
,
K.
Torii
,
H.
Furutou
,
A.
Ohta
,
P.
Ahmet
,
K.
Ohmori
,
H.
Watanabe
,
T.
Chikyow
,
M. L.
Green
,
Y.
Nara
, and
K.
Yamada
,
2005 IEDM Tech. Digest
, p.
43
(
2005
).
18.
J.
Robertson
,
J. Non-Cryst. Solids
303
,
94
(
2002
).
19.
O.
Kubaschewski
,
C. B.
Alcock
, and
P. J.
Spencer
,
Materials Thermochemistry
(
Pergamon
,
London
,
1993
).
20.
F. R.
de Boer
,
R.
Boom
,
W. C. M.
Mattens
,
A. R.
Miedema
, and
A. K.
Niessen
,
Cohesion in Metals, Cohesion and Structure
(
North-Holland
,
Amsterdam
,
1988
), Vol.
1
.
21.
W. X.
Li
,
L.
Österlund
,
E. K.
Vestergaard
,
R. T.
Vang
,
J.
Matthiesen
,
T. M.
Pedersen
,
E.
Lægsgaard
,
B.
Hammer
, and
F.
Besenbacher
,
Phys. Rev. Lett.
93
,
146104
(
2004
).
22.
H.
Takeuchi
,
D.
Ha
, and
T. -J.
King
,
J. Vac. Sci. Technol. A
22
,
1337
(
2004
).
23.
E.
Cartier
,
F. R.
McFeely
,
V.
Narayanan
,
P.
Jamison
,
B. P.
Linder
,
M.
Copel
,
V. K.
Paruchuri
,
V. S.
Basker
,
R.
Haight
,
D.
Lim
,
R.
Carruthers
,
T.
Shaw
,
M.
Steen
,
J.
Sleight
,
J.
Rubino
,
H.
Deligianni
,
S.
Guha
,
R.
Jammy
, and
G.
Shahidi
,
2005 VLSI Symposium Tech. Digest
, p.
230
(
2005
).
24.
J. K.
Schaeffer
,
L. R. C.
Fonseca
,
S. B.
Samavedam
,
Y.
Liang
,
P. J.
Tobin
, and
B. E.
White
,
Appl. Phys. Lett.
85
,
1826
(
2004
).
You do not currently have access to this content.