Effect of atomic layer deposition temperature on current conduction in Al{sub 2}O{sub 3} films formed using H{sub 2}O oxidant

To develop high-performance, high-reliability gate insulation and surface passivation technologies for wide-bandgap semiconductor devices, the effect of atomic layer deposition (ALD) temperature on current conduction in Al{sub 2}O{sub 3} films is investigated based on the recently proposed space-cha...

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Bibliographic Details
Published in:Journal of applied physics 2016-08, Vol.120 (8)
Main Authors: Hiraiwa, Atsushi, Matsumura, Daisuke, Kawarada, Hiroshi, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, The Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku, Tokyo 169-0051
Format: Article
Language:English
Subjects:
AFFINITY
ALUMINIUM OXIDES
CAPACITORS
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
DEPOSITION
DIPOLES
ELECTRIC POTENTIAL
ELECTRONS
FIELD EMISSION
LEAKAGE CURRENT
PASSIVATION
PERMITTIVITY
SEMICONDUCTOR DEVICES
SEMICONDUCTOR MATERIALS
SILICA
SILICON OXIDES
SPACE CHARGE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0400-1000 K
WATER
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Summary:To develop high-performance, high-reliability gate insulation and surface passivation technologies for wide-bandgap semiconductor devices, the effect of atomic layer deposition (ALD) temperature on current conduction in Al{sub 2}O{sub 3} films is investigated based on the recently proposed space-charge-controlled field emission model. Leakage current measurement shows that Al{sub 2}O{sub 3} metal-insulator-semiconductor capacitors formed on the Si substrates underperform thermally grown SiO{sub 2} capacitors at the same average field. However, using equivalent oxide field as a more practical measure, the Al{sub 2}O{sub 3} capacitors are found to outperform the SiO{sub 2} capacitors in the cases where the capacitors are negatively biased and the gate material is adequately selected to reduce virtual dipoles at the gate/Al{sub 2}O{sub 3} interface. The Al{sub 2}O{sub 3} electron affinity increases with the increasing ALD temperature, but the gate-side virtual dipoles are not affected. Therefore, the leakage current of negatively biased Al{sub 2}O{sub 3} capacitors is approximately independent of the ALD temperature because of the compensation of the opposite effects of increased electron affinity and permittivity in Al{sub 2}O{sub 3}. By contrast, the substrate-side sheet of charge increases with increasing ALD temperature above 210 °C and hence enhances the current of positively biased Al{sub 2}O{sub 3} capacitors more significantly at high temperatures. Additionally, an anomalous oscillatory shift of the current-voltage characteristics with ALD temperature was observed in positively biased capacitors formed by low-temperature (≤210 °C) ALD. This shift is caused by dipoles at the Al{sub 2}O{sub 3}/underlying SiO{sub 2} interface. Although they have a minimal positive-bias leakage current, the low-temperature-grown Al{sub 2}O{sub 3} films cause the so-called blisters problem when heated above 400 °C. Therefore, because of the absence of blistering, a 450 °C ALD process is presently the most promising technology for growing high-reliability Al{sub 2}O{sub 3} films.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4961520