of Effects NH3 as a Catalyst on the Metalorganic Chemical Vapor Deposition of Al2O3
Final Presentation for REU program August 3rd, 2006 Ashlynne Rhoderick University of South Carolina Department of Chemical Engineering Advisor: Dr. Christos Takoudis University Of Illinois-Chicago Department of Chemical Engineering
Motivation for Research
Need for increased circuit density
Fitting more transistors on each wafer
Physical limit of SiO2
High leakage current Reliability Boron penetration C=0A/t
C- capacitance - dielectric coefficient (or relative permittivity) 0- permittivity of free space (8.85*10-3 fF/m) A- area of capacitor t- thickness of the dielectric
Finding a new dielectric
SiO2 = 3.9 Need a higher dielectric
http://www.hpc.unm.edu/~acpineda/research/movies/movies.html
Why Al2O3 as a possible dielectric?
Positive characteristics
=9
Thermodynamically stable in contact with Si Very stable, robust High band gap (9 eV) It can combined with other high k dielectric material
Experiment with NH3
Hope that it will
Increase the deposition rate of Al2O3 Decrease deposition temperature Decrease amount of impurities in film
Set Up of Experiment
Cut 2 cm x 2 cm silicon wafers
Cleaning procedure
http://www.imps.co.uk/imps%2013-11-03/index_act.htm
Ultrasonic cleaning-loosens particles (1 min) Distilled water- removes particles (3 min) 4:1 H2SO4/H2O2- remove organic material (15 min) Distilled water (3 min) 49% HF- remove native silicon oxide (15 sec) Distilled water (3 min) Dry with nitrogen
Metal Organic Chemical Vapor Deposition
Reaction conditions
Deposition temperature: 100, 200, 300, 400, and 500C Deposition pressure: 0.7-0.8 torr
Anand Deshpande Ph.D. Thesis, UIC (2005)
Analysis Techniques
Ellipsometric Spectroscopy
Thickness
X-Ray Photoelectron Spectroscopy (XPS)
Stoichiometry, Composition
Fourier Transform Infrared Spectroscopy (FTIR)
Composition
Comparing the Results
10 Al2O3 Deposition rate (nm/cycle) 8 6 4 2 0
without NH3 with NH3
0
100
200
300
400
500
600
Deposition temperature (oC)
XPS Analysis
XPS Survey for film catalyzed with NH3 at 200C
O 1s
No Etch 600 Etch
Ar
Al 2p
C 1s
N 1s
0
200
400
600 Binding Energy (eV)
800
1000
1200
XPS Analysis: Stoichiometric
O/Al ratio Temperature (C) No Etch 300 sec Etch 600 sec Etch Sample1 Sample3 Sample2 Sample4 No NH3 300 1.596 1.490 1.472 200 1.619 1.493 1.479 300 1.671 1.608 1.560 NH3 200 1.638 1.540 1.534
From 2006 experiments
2004 experiments by A. Roy Chowdhuri and C.G. Takoudis
Stoichiometric ratio of O/Al was 2.0 0.1
FTIR Analysis
Conclusions and Future Work
NH3 raised the deposition rate in the temperature range of 200-300C Without Ammonia
Absorption controlled until 300C Reaction controlled after 300C
With Ammonia
Reaction controlled from 100-300C At 100C ammonia absorbed gets therefore less TMA is absorbed results in lower Al2O3 deposition rate
Purity of the film was not compromised Continue to perfect use of NH3 in the deposition of Al2O3
References
Brewer, R.T. et al. (2004) Ammonia pretreatment for high-k dielectric growth on silicon. Applied Physics Letters. 85, 38303832. Chowdhuri, A. Roy and Takoudis, C.G. (2004) Investigation of the aluminum oxide/ Si (1 0 0 ) interface formed by chemical vapor deposition. Thin Solid Films. 446, 155-159. Hiremane, Radhakrishna. (2005) From Moores Law to Intel InnovationPrediction to Reality. Technology @ Intel Magazine. 1-9. Jung, Sung-Hoon and Kang, Sang-Won (2001) Formation pf TiO2 Thin Films using NH3 as Catalyst by Metalorganic Chemical Vapor Deposition. Japan Society of Applied Physics 40, 3147-3152. Klaus, J.W. and George, S.M. (2000) Atomic layer deposition of SiO2 at room temperature using NH3-catalyzed sequential surface reactions. Surface Science. 447, 81-90. Klein, T.M. et al. (1999) Evidence of aluminum silicate formation during chemical vapor deposition of amorphous Al2O3 thin films on Si(100). Applied Physics Letters. 75, 4001-4003. Krug, C. et al. (2000) Atomic Transport and Chemical Stability during Annealing of Ultrathin Al2O3 Films on Si. 85, 41204123. Ong, C.W. et al. (1997) Structural Studies of reactive Pulsed Laser-Deposited CNx Films by X-ray Photoelectron Spectroscopy and Infrared Absorption. Journal of The Electrochemical Society. 32, 2347-2352. Ogita, Y. et al. (2003) Al2O3 formation on Si by catalytic chemical vapor deposition. Thin Solid Films. 430, 161-164. Pradhan, Siddhartha K. et al (2003). Growth of TiO2 nanorods by metalorganic chemic...