Laser annealed Hfx Zr1-x O2 high- k dielectric: Impact on morphology, microstructure, and electrical properties

Article abstract of DOI:10.1063/1.2898710

The impact of microsecond laser annealing at 1325 °C on physical and electrical characteristics of Hfx Zr1-x O2 is compared to films annealed at 1000 °C for 5 s by a conventional rapid thermal process (RTP). Atomic force microscopy analysis shows that laser annealed Hfx Zr1-x O2 is smoother and void free, while RTP annealed Hfx Zr1-x O2 exhibits void formation and is rough. The x-ray diffraction analysis revealed higher degree of tetragonality on laser annealed film, particularly for Hf0.5 Zr0.5 O2 and Zr O2. Furthermore, laser annealed Hfx Zr1-x O2 devices have good electrical properties (well behaved CV, low gate leakage, and good mobility) whereas RTP annealed devices are not functional.

Full text of DOI:10.1063/1.2898710

Laser annealed Hf x Zr 1 − x O 2 high- k dielectric: Impact on morphology,
microstructure, and electrical properties
Dina H. Triyoso, Greg Spencer, Rama I. Hegde, Rich Gregory, and Xiang-Dong Wang
Citation: Applied Physics Letters 92, 113501 (2008); doi: 10.1063/1.2898710
View online: http://dx.doi.org/10.1063/1.2898710
View Table of Contents: http://scitation.aip.org/content/aip/journal/apl/92/11?ver=pdfcov
Published by the AIP Publishing
Articles you may be interested in
Multi-technique x-ray and optical characterization of crystalline phase, texture, and electronic structure of atomic
layer deposited Hf1−xZrxO2 gate dielectrics deposited by a cyclical deposition and annealing scheme
J. Appl. Phys. 113, 234101 (2013); 10.1063/1.4811446
Macroscopic and microscopic electrical characterizations of high- k ZrO 2 and ZrO 2 / Al 2 O 3 / ZrO 2 metal-
insulator-metal structures
J. Vac. Sci. Technol. B 29, 01AC02 (2011); 10.1116/1.3523397
Interfacial and electrical properties of Zr x Ti 1 − x O 4 ( x = 0.66 ) films deposited by liquid-delivery metal organic
chemical vapor deposition to be used as high- k gate dielectric
J. Vac. Sci. Technol. B 26, 1338 (2008); 10.1116/1.2945302
Characteristics of atomic-layer-deposited thin Hf x Zr 1 − x O 2 gate dielectrics
J. Vac. Sci. Technol. B 25, 845 (2007); 10.1116/1.2734978
Impact of Zr addition on properties of atomic layer deposited Hf O 2
Appl. Phys. Lett. 88, 222901 (2006); 10.1063/1.2208558
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
129.21.35.191 On: Sun, 21 Dec 2014 19:14:42

APPLIED PHYSICS LETTERS 92, 113501 ͑2008͒
Laser annealed Hf Zr O high-k dielectric: Impact on morphology,
x
1−x
2
microstructure, and electrical properties
a͒
Dina H. Triyoso, Greg Spencer, Rama I. Hegde, Rich Gregory, and Xiang-Dong Wang
Technology Solutions Organization, Freescale Semiconductor, Inc., 3501 Ed Bluestein Blvd., Austin,
Texas 78721, USA
͑
Received 6 February 2008; accepted 27 February 2008; published online 17 March 2008͒
The impact of microsecond laser annealing at 1325 °C on physical and electrical characteristics of
Hf Zr O is compared to films annealed at 1000 °C for 5 s by a conventional rapid thermal
x
1−x
2
process ͑RTP͒. Atomic force microscopy analysis shows that laser annealed Hf Zr O is smoother
x
1−x
2
and void free, while RTP annealed Hf Zr O exhibits void formation and is rough. The x-ray
x
1−x
2
diffraction analysis revealed higher degree of tetragonality on laser annealed film, particularly for
Hf Zr O and ZrO . Furthermore, laser annealed Hf Zr1−xO2 devices have good electrical
0
.5 0.5
2
2
x
properties ͑well behaved CV, low gate leakage, and good mobility͒ whereas RTP annealed devices
are not functional. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2898710͔
As transistor size continues to shrink, the scaling of SiO2
gate dielectrics reaches its limit. In the past decades, the
semiconductor industry has expended much effort to find re-
and low temperature deposition. Recently, ALD has been
used to deposit thin high-k films to manufacture dynamic
7
random access memory. In this letter, we report physical and
placement materials for SiO gate oxide. In recent years, the
industry has converged on hafnium-based high-dielectric
electrical characteristics of microsecond laser annealed films
and compare them to films given conventional RTP anneal.
We found that laser annealing is a favorable method of an-
nealing ALD high-k films compared to RTP anneal.
2
constant ͑high-k͒ materials as the most promising SiO
2
1
–5
replacement.
Encouraging results on hafnium-based de-
vices ͑HfO , Hf Zr O , and HfSiON͒ have been reported
HfO and Hf Zr O films were fabricated by ALD us-
2
x
1−x
–5
2
2
x
1−x
2
2
by many groups. Crystallization properties of these films
have been widely studied using conventional rapid thermal
process ͑RTP͒ anneals. Recently, however, microsecond laser
annealing of high-k/metal gate devices has been reported to
ing HfCl , ZrCl , and D O precursors at a deposition tem-
4 4 2
8
,9
perature of 300 °C as previously reported. All films were
either annealed at 1000 °C for 5 s in a nitrogen ambient or
6
laser annealed. The laser anneals were performed using the
6
10–13
have advantages over conventional RTP annealing. How-
Ultratech LSA platform,
rastering the subject wafer on a
ever, the impact of laser annealing on properties of hafnium-
based high-k films has not been studied in detail. In this
letter, we report the impact of laser annealing on hafnium-
based high-k films.
Among the various methods used to deposit thin high-k
dielectrics, atomic layer deposition ͑ALD͒ provides some ad-
vantages such as excellent thickness control, conformality,
heated chuck under a high power of 10.6 ␮m wavelength
laser beam incident upon the wafer’s surface near Brewster’s
angle. The beam was rastered using an 800 ␮s beam dwell
time with a beam width on the order of 100 ␮m. The laser
power was adjusted to determine the peak anneal tempera-
ture to be between 1275 and 1325 °C. The laser anneal peak
temperature was calibrated relative to the melt temperature
FIG. 1. ͑Color online͒ AFM of laser
annealed vs RTP annealed Hf Zr1−xO2
x
films.
a͒Electronic mail: dina.triyoso@freescale.com.
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
003-6951/2008/92͑11͒/113501/3/$23.00 92, 113501-1 © 2008 American Institute of Physics
29.21.35.191 On: Sun, 21 Dec 2014 19:14:42
0
1

113501-2
Triyoso et al.
Appl. Phys. Lett. 92, 113501 ͑2008͒
FIG. 2. ͑Color online͒ XRD of laser
anneal vs RTP annealed ͑a͒ HfO , ͑b͒
2
Hf0.5Zr0.5O , and ͑c͒ ZrO films.
2
2
of silicon. Rutherford backscattering spectroscopy analysis
electrode and capped with poly-Si. The high-k dielectric
was performed to determine the composition of Hf Zr1−xO2
films were deposited on “cake oxide” wafers with pregrown
x
alloy and to confirm that film composition does not change
SiO thickness. Transistors were fabricated using conven-
2
9
,14,15
significantly after annealing.
Film roughness was mea-
tional complementary metal-oxide semiconductor integration
with sidewall liners and spacers, implants to the Si cap/
source/drain, 1000 °C activation anneal, cobalt-salicide con-
tacts, and forming gas anneal. Equivalent oxide thickness
was extracted using the HAUSER program, while mobility
sured by atomic force microscopy ͑AFM͒ operated in tap-
ping mode. The root mean square roughness values were
2
calculated on 1ϫ1 ␮m images. X-ray diffraction ͑XRD͒ in
powder mode was used to determine the preferred orienta-
tion of the films. Instrumentation consisted of a Rigaku Ro-
taflex RU-200BH with Cu K␣ rotating anode and Dmax-B-
goniometer. For electrical characterization, ϳ30 Å high-k
6
,16
was determined using MOB2D as previously reported.
Figure 1͑a͒ shows AFM images of 3 nm Hf Zr1−xO2
x
͑x=0, 0.5, and 1͒ after a microsecond laser anneal or a con-
dielectric deposition was followed with a TaC metal gate
ventional RTP anneal. All laser annealed films are void free,
y
FIG.
3.
͑Color
online͒
͑a͒
Capacitance-voltage, ͑b͒ gate leakage
current-voltage, and ͑c͒ mobility
of laser annealed vs RTP annealed
Hf Zr1−xO2 devices. Device size is
x
2
8
5ϫ80 ␮m .
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
29.21.35.191 On: Sun, 21 Dec 2014 19:14:42
1

113501-3
Triyoso et al.
Appl. Phys. Lett. 92, 113501 ͑2008͒
TABLE I. Summary of impact of LSA on Hf0.5Zr0.5O2 film morphology,
microstructure, and device properties.
device properties when compared to RTP annealed films. Not
only the films are smoother and void free, these films crys-
tallize more in the tetragonal phase which has a higher-k
value than the monoclinic phase. Electrically, laser annealed
Hf0.5Zr0.5O2
RTP
LSA
films yield good devices, whereas RTP annealed Hf Zr1−xO2
x
devices are leaky and not functional.
AFM-roughness ͑nm͒
XRD-tetragonality ͑%͒
Well-behaved CVs?
0.25
0.16
12.5
0
The authors would like to thank Suresh Venkatesan for
management support. The authors also thank Darrell Roan,
Ross Noble, Ricardo Garcia, Laura Contreras, and Jen-Yee
Nguyen for technical assistance. The authors thank Jamie
Schaeffer, David Gilmer, and Sri Samavedam for helpful
discussion.
No
Yes
7.2ϫ10−8
2.1ϫ10−2
¯
Jg͑A͒ at 1 V
P
e
a
k
G
c
o
m
p
a
r
e
d
t
o
S
i
O
90.3%
m
2
͑
as opposed to the RTP annealed film, which show evidence
1
of void formation͒ and are smoother than the RTP annealed
films. It appears that the ultrashort duration of the laser an-
neal helps us to significantly reduce void formation that oc-
curs when these ALD high-k films are exposed to high tem-
perature annealing for times on the order of seconds. To
further investigate the microstructure of these films, XRD
spectra were recorded for ϳ200 Å Hf Zr O ͑x=0, 0.5,
G. D. Wilk, R. M. Wallace, and J. M. Anthony, J. Appl. Phys. 89, 5243
͑2001͒.
2
P. D. Kirsch, M. A. Quevedo-Lopez, S. A. Krishnan, C. Krug, H. AlSha-
reef, C. S. Park, R. Harris, N. Moumen, A. Neugroschel, G. Bersuker, B.
H. Lee, J. G. Wang, G. Pant, B. Gnade, M. J. Kim, R. M. Wallace, J. S.
Jur, D. J. Lichtenwalner, and A. I. Kingon, and R. Jammy, Tech. Dig. - Int.
Electron Devices Meet. 2006, 4.
3
H.-H. Tseng, P. J. Tobin, S. Kalpat, J. K. Schaeffer, M. E. Ramon, L. R. C.
x
1−x
2
Fonseca, Z. X. Jiang, R. I. Hegde, D. H. Triyoso, and S. Samavedam,
and 1͒ after both annealing conditions. Figure 2͑a͒ shows
IEEE Trans. Electron Devices 54, 3267 ͑2007͒.
R. I. Hegde, D. H. Triyoso, P. J. Tobin, and B. E. White, Jr., J. Appl. Phys.
XRD spectra of ϳ20 nm HfO films after a 1000 °C anneal
4
2
for 5 s in a nitrogen ambient compared to laser annealed
1
01, 074113 ͑2007͒.
5
films. Both films are monoclinic and exhibit strong ͑111͒ or
W. J. Taylor, Jr., C. Capasso, B. Min, B. Winstead, E. Verret, K. Loiko, D.
Gilmer, R. I. Hegde, J. Schaeffer, E. Luckowski, A. Martinez, M. Ray-
mond, C. Happ, D. Triyoso, S. Kalpat, A. Haggag, D. Roan, J.-Y. Nguyen,
L. B. La, L. Hebert, J. Smith, D. Jovanovic, M. Foisy, S. B. Samavedam,
N. Cave, B. E. White, Jr., and S. Venkatesan, Tech. Dig. - Int. Electron
Devices Meet. 2006, 625.
͑
111͒ texture. Figure 2͑b͒ shows XRD spectra of Hf Zr O
0.5 0.5 2
films after RTP or laser annealing. The spectra reveal that the
RTP film is mostly monoclinic with perhaps a slight hint of
tetragonal phase ͑broad peak at 30° theta͒, whereas the laser
annealed Hf Zr O film has a more pronounced peak at 30°
6
D. C. Gilmer, J. K. Schaeffer, W. J. Taylor, G. Spencer, D. H. Triyoso, M.
Raymond, D. Roan, J. Smith, C. Capasso, R. I. Hegde, and S. B. Sa-
mavedam, Proceedings of the 36th European Solid-State Device Research
Conference, 2006 ͑unpublished͒, p. 351.
x
1−x
2
indicating tetragonal phase. The XRD spectra in Fig. 2͑c͒
show that the laser annealed film has greater tetragonality
than the RTP annealed films as evidenced by stronger peak at
7
See http://www.micromagazine.com/archive/05/07/chipworks.html for ar-
ticle on ALD high-k DRAM.
H.-H. Tseng, M. E. Ramon, L. Hebert, P. J. Tobin, D. Triyoso, J. M. Grant,
Z. X. Jiang, D. Roan, S. B. Samavedam, D. C. Gilmer, S. Kalpat, C.
Hobbs, W. J. Taylor, O. Adetutu, and B. E. White, Tech. Dig. - Int. Elec-
tron Devices Meet. 2003, 4.1.1.
30° and relatively weaker monoclinic peaks. The evidence
8
that tetragonal phase stabilization is more pronounced in the
laser annealed material is encouraging because tetragonal
phase Hf Zr O with its higher-k value is more desirable
x
1−x
2
4
,9,15–19
phase than monoclinic phase material.
It is known that
9
D. H. Triyoso, P. J. Tobin, B. E. White, Jr., R. Gregory, and X.-D. Wang,
the driving force for the tetragonal to monoclinic transforma-
tion is smaller when ZrO is alloyed into the HfO . This is
Appl. Phys. Lett. 89, 132903 ͑2006͒.
1
0
A. Shima and A. Hiraiwa, Jpn. J. Appl. Phys., Part 1 45, 5708 ͑2006͒.
S. K. H. Fung, H. T. Huang, S. M. Cheng, K. L. Cheng, S. W. Wang, Y. P.
Wang, Y. Y. Yao, C. M. Chu, S. J. Yang, W. J. Liang, Y. K. Leung, C. C.
Wu, C. Y. Lin, S. J. Chang, S. Y. Wu, C. F. Nieh, C. C. Chen, T. L. Lee,
Y. Jin, S. C. Chen, L. T. Lin, Y. H. Chiu, H. J. Tao, C. Y. Fu, S. M. Jang,
K. F. Yu, C. H. Wang, T. C. Ong, Y. C. See, C. H. Diaz, M. S. Liang, and
Y. C. Sun, 2004 Symposium on VLSI Technology: Digest of Technical
Papers ͑IEEE, Piscataway, NJ, 2004͒, pp. 92–93.
2
2
11
more exaggerated in the case of millisecond anneal. Micro-
structure modification due to laser annealing has also been
2
0
recently reported for La O system. Laser annealing results
2
3
in a significantly higher-k value for La O than those ob-
2
3
2
0,21
tained by conventional anneal.
To investigate electrical properties of laser annealed
films, long channel transistors and capacitors were fabri-
cated. Figure 3͑a͒ shows capacitance voltage characteristics
of laser annealed devices. CV curves from multiple sites are
coplotted and show very little site to site variation, indicating
good uniformity. No functional CV were obtained for RTP
annealed devices. RTP annealed devices are very leaky, as
shown in Fig. 3͑b͒. This is not surprising as AFM images
show evidence of void formation in Hf Zr O films after
1
1
2
L. M. Feng, Y. Wang, and D. A. Markle, International Workshop on Junc-
tion Technology, 2006 ͑unpublished͒, pp. 1–5.
3
S. Chen, J. Hebb, A. Jain, S. Shetty, and Y. Wang, Proceedings of the 15th
IEEE International Conference on Advanced Thermal Processing of Semi-
conductors 2007 ͑unpublished͒.
D. H. Triyoso, R. I. Hegde, J. K. Schaeffer, D. Roan, P. J. Tobin, S. B.
Samavedam, B. E. White, R. Gregory, and X.-D. Wang, Appl. Phys. Lett.
1
1
1
4
5
6
8
8, 222901 ͑2006͒.
D. H. Triyoso, R. I. Hegde, J. K. Schaeffer, R. Gregory, X.-D. Wang, M.
Canonico, D. Roan, E. A. Hebert, K. Kim, J. Jiang, R. Rai, V. Kaushik,
and S. B. Samavedam, J. Vac. Sci. Technol. B 25, 845 ͑2007͒.
D. H. Triyoso, R. I. Hegde, J. Jiang, J. K. Schaeffer, and M. V. Raymond,
IEEE Electron Device Lett. 29, 57 ͑2008͒.
x
1−x
2
high temperature RTP annealing. Figure 3͑c͒ plots mobility
of laser annealed Hf Zr O devices showing excellent mo-
x
1−x
2
bility compared to the universal SiO curve. Table I summa-
17
2
X. Zhao and D. Vanderbilt, Phys. Rev. B 65, 233106 ͑2002͒.
X. Zhao and D. Vanderbilt, Phys. Rev. B 65, 075105 ͑2002͒.
C. Fachmann, L. Frey, S. Kudelka, T. Boescke, S. Nawka, E. Erben, and T.
Doll, Microelectron. Eng. 84, 2883 ͑2007͒.
1
1
8
9
rizes electrical and material properties of Hf Zr O after
x
1−x
2
RTP or laser anneal.
In summary, the impact of laser annealing versus con-
ventional RTP annealing on physical and electrical properties
of hafnium-based dielectrics is studied. Results show that
laser annealed films have significantly improved material and
2
2
0
P. Darmawan, P. S. Lee, Y. Setiawan, J. Ma, and T. Osipowicz, Appl.
Phys. Lett. 91, 092903 ͑2007͒.
1
S. Ohmi, M. Takeda, H. Ishiwara, and H. Iwai, J. Electrochem. Soc. 151,
G279 ͑2004͒.
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
129.21.35.191 On: Sun, 21 Dec 2014 19:14:42