Microstructure and thermal stability of HfO2 gate dielectric deposited on Ge(100)
- 20 September 2004
- journal article
- research article
- Published by AIP Publishing in Applied Physics Letters
- Vol. 85 (12) , 2334-2336
- https://doi.org/10.1063/1.1794849
Abstract
We report on physical and electrical characterization of ultrathin ( 3 – 10 nm ) high- κ HfO 2 gate stacks deposited on Ge ( 100 ) by atomic-layer deposition. It is observed that uniform films of HfO 2 can be deposited on Ge without significant interfacial growth. The lack of an interlayer enables quasiepitaxial growth of HfO 2 on the Ge surface after wet chemical treatment whereas a nitrided interface(grown by thermal oxynitridation in ammonia) results in an amorphous HfO 2 . The stacks exhibit surprisingly good thermal stability, up to temperatures only 150 ° C below the melting point of Ge . In terms of electrical properties, HfO 2 on Ge shows significantly reduced (up to 4 decades) gate leakage currents in the ultrathin regime of equivalent electrical thickness down to ∼ 1.4 nm due to the high-dielectric constant of ∼ 23 . Nitrided interface is observed to be important for good insulating properties of the stack.Keywords
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