Thermal behavior of the microstructure and the electrical properties of magnetron-sputtered high-k titanium silicate thin films

Journal Article · Sun Jun 01 00:00:00 EDT 2008 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2937241· OSTI ID:21137344

Brassard, D; El Khakani, M A ^[1]

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1. Institut National de la Recherche Scientifique, INRS-Energie, Materiaux et Telecommunications, 1650 Boulevard Lionel-Boulet, C.P. 1020, Varennes, Quebec J3X 1S2 (Canada)

We report on the high-temperature stability of high-dielectric-constant (high-k) titanium silicate (Ti{sub 0.5}Si{sub 0.5}O{sub 2}) thin films deposited by means of a magnetron sputtering process. We have investigated the effect of substrate deposition temperature T{sub d} (in the 20-600 deg. C range) and postdeposition annealing temperature T{sub a} (in the 200-800 deg. C range) on the electrical, microstructural, and optical properties of the films. The Ti-silicate films grown at room temperature were found to exhibit a combination of excellent electrical properties, including a k-value of 16.5, a leakage current as low as 3 nA at 1 MV/cm, and a dissipation factor tan({delta})<0.01. On the other hand, when the processing temperature (T{sub d} or T{sub a}) is {>=}300 deg. C, the leakage current of the films is found to degrade progressively. The x-ray diffraction, Raman spectroscopy, and transmission electron microscopy characterizations have shown that the Ti-silicate films exhibit an amorphous microstructure up to a temperature of about 600 deg. C. For higher temperatures, (i.e., T{sub d} of 600 deg. C or a T{sub a}{>=}700 deg. C) some anatase TiO{sub 2} nanocrystallites (in the 1.5-5 nm size range) formation is evidenced. This TiO{sub 2} nanocrystallite precipitation results from a thermally induced phase segregation of TiO{sub 2}-rich and SiO{sub 2}-rich environments, which is shown to be initiated at rather low processing temperatures. This progressive phase segregation, which leads to the precipitation of a low band gap and leaky TiO{sub 2}-rich phase in the films, is believed to be at the origin of the observed degradation of the leakage current of the Ti-silicate films with increasing temperatures (T{sub d} or T{sub a})

• OSTI ID: 21137344
• Journal Information: Journal of Applied Physics, Vol. 103, Issue 11; Other Information: DOI: 10.1063/1.2937241; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
DIELECTRIC MATERIALS
DISSIPATION FACTOR
LEAKAGE CURRENT
MICROSTRUCTURE
NANOSTRUCTURES
RAMAN SPECTROSCOPY
SEGREGATION
SEMICONDUCTOR MATERIALS
SILICON OXIDES
SPUTTERING
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
THIN FILMS
TITANIUM OXIDES
TITANIUM SILICATES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION