Microstructure and deposition rate of aluminum thin films from chemical
vapor deposition with dimethylethylamine alane
Byoung-Youp Kim,a) Xiaodong Li,b) and Shi-Woo Rheec)
Laboratory for Advanced Materials Processing (LAMP), Department of Chemical Engineering, Pohang
University of Science and Technology (POSTECH), Pohang 790-784, Korea
͑Received 4 December 1995; accepted for publication 17 April 1996͒
Deposition of aluminum film from DMEAA in the temperature range of 100–300 °C has been
studied. In this temperature range, there is a maximum deposition rate at around 150 °C. The film
deposited at 190 °C has elongated blocklike grain shapes, which are ϳ600 nm in width and 930 nm
in length. Grains in the film deposited at 150 °C showed an equiaxed structure with grain size in the
range of 100–300 nm in a film with 600 nm thickness. Aluminum oxide particle inclusion was
observed especially at high deposition temperature. Plausible reaction pathways of DMEAA
dissociation were suggested to explain the experimental observations. © 1996 American Institute
of Physics. ͓S0003-6951͑96͒03825-9͔
Aluminum has been widely used as a conducting mate-
rial in the fabrication of integrated circuits. So far, most
commercial Al films have been deposited by physical vapor
deposition, but chemical vapor deposition usually gives more
conformal coverage of a surface and allows a reactor design
for multiwafer processing to give high throughput. For this
reason, Al chemical vapor deposition ͑CVD͒ has been ac-
tively investigated for ULSI applications like 256 Mbit or 1
Gbit DRAM fabrication.
Previous works related to Al CVD precursors and reac-
tion mechanisms have been reviewed comprehensively by
Simmonds and Gladfelter.1 For the deposition of aluminum,
alkyl aluminum and amine-alane adducts have been used ex-
tensively. DMEAA, an adduct of alane (AlH3) and dimeth-
such as TiN, Al, Si, and SiO2 with deposition temperature
between 100 and 300 °C and pressure at 0.2 mbar. The base
pressure before the deposition was 1.5ϫ10Ϫ6 mbar. A sub-
strate surface of TiN and Al was sputter deposited on a sili-
con wafer and the SiO2 surface was obtained by thermal
oxidation of a silicon wafer.
Figure 1 shows the amount of Al deposited on various
substrate surfaces as a function of deposition time at a depo-
sition temperature of 200 °C. The induction time, during
which no appreciable deposition had been observed, was
quite long on Si and SiO2 surfaces. In that case, discontinu-
ous film was formed and adhesion was very poor. On the
TiN and Al surface, induction time was negligible and adhe-
sion was good. From this observation, we could conclude
that selective deposition is possible on TiN or Al over the Si
or SiO2 surface. As the deposition temperature goes up, the
induction time becomes shorter and it becomes more difficult
to achieve selective deposition. As the surface is covered
with Al, the slope, i.e., the deposition rate, should be the
same regardless of the substrate surface, but it seems that
depending on the nucleation behavior at the initial stage, the
deposition rate is slightly different.
ylethylamine N(CH ) C H , is the most recently intro-
͓
͔
3
2
2
5
duced member of the amine family of precursors. Its
relatively high vapor pressure at room temperature ͑1.5
Torr͒, its long shelf life, its ability to deposit carbon
contamination-free films, combined with the advantages of
being a liquid have recently made it the precursor of atten-
tion. The deposition behavior and chemistry of DMEAA,2
have been studied including selective deposition3,4 but study
of the microstructure of Al films and data related to the depo-
sition rate and chemical reaction kinetics is still lacking.
In this letter, experimental results, mainly the deposition
rate and microstructure of the film as a function of deposition
temperature, obtained from chemical vapor deposition of
aluminum with DMEAA are described.
Figure 2 shows the deposition rate of Al film on the TiN
surface as a function of deposition temperature. The deposi-
tion rate increased to a maximum at around 150 °C and then
CVD of aluminum was carried out in a homemade, low
pressure, cold wall, single wafer reactor. DMEAA was intro-
duced directly without a carrier gas through vapor phase
mass flow controller, MKS mass-flo type 1150. DMEAA
with a rate of 0.01 ml/min in liquid volume was introduced
from above through a cylindrical showerhead-type distribu-
tor and flowed down vertically toward the wafer surface. The
gap distance between the showerhead and the susceptor was
3 cm. Al film was deposited on various substrate surfaces
a͒
Present address: LG Semicon Co., ULSI Research Center, Chung-ju,
Korea.
b͒
Present address: Department of Mechanical Engineering, Ohio State Uni-
versity, Columbus, OH 43210.
FIG. 1. Amount of Al deposited on various substrate surfaces as a function
of deposition time at a deposition temperature of 200 °C and a pressure of
0.2 mbar.
c͒
Electronic mail: srhee@vision.postech.ac.kr
Appl. Phys. Lett. 68 (25), 17 June 1996
0003-6951/96/68(25)/3567/3/$10.00
© 1996 American Institute of Physics
3567
Kim, Byoung-Youp
