Berlin 2008 – scientific programme

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DS: Fachverband Dünne Schichten

DS 23: High-k Dielectric Materials - Synthesis, Properties, Applications
The posters can also be presented at Poster A on Tuesday morning (DS poster session).

DS 23.10: Poster

Wednesday, February 27, 2008, 18:30–20:30, Poster C

Fully depleted SOI-nMOSFETs with Gadolinium scandate as high-κ dielectric. — •M. Roeckerath¹, J. M. J. Lopes¹, T. Heeg², J. Schubert¹, and S. Mantl¹ — ¹Institute of Bio- and Nanosystems and Center of Nanoelectronic Systems for Information Technology, Research Centre Juelich, D-52425 Juelich, Germany — ²Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802-5005, USA

Rare earth scandates are a promising class of materials as alternative high-κ gate dielectrics for future CMOS applications due to their good morphological and electrical properties (D. G. Schlom et. al., MRS Bull. 27, 198 (2002)). In particular, gadolinium scandate has recently attracted increasing attention since it exhibits a high thermal stability, a sufficiently large κ-value of ∼23 and is in contrast to other rare earth oxides not hygroscopic. In this work long channel n-metal-oxide-semiconductor field-effect transistors (nMOSFETs) on thin SOI (∼25 nm) have been prepared with gadolinium scandate as high-κ gate dielectric and a TiN metal gate in a gate last process. The GdScO₃ films were deposited by electron beam evaporation from a stoichiometric ceramic target in high vacuum conditions. Prior to the deposition different surface treatments of the substrates were applied to vary the interface conditions. Readily fabricated devices were electrically characterized by DC-measurements. They reveal well behaved output and transfer characteristics with high I_on/I_off ratios of 10⁶-10⁸ and steep inverse subthreshold slopes of ∼66 mV/dec. Carrier mobilities comparable to other high-k dielectrics of ∼150 cm²/Vs were determined.