Dresden 2009 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 5: High-k and low-k Dielectrics

DF 5.3: Talk

Monday, March 23, 2009, 15:40–16:00, WIL B321

Ternary rare-earth based alternative gate-dielectrics for future integration in MOSFETs — •Jürgen Schubert, Joao Marcelo Lopes, Eylem Durgun Özben, Roman Luptak, Steffi Lenk, Willi Zander, and Martin Roeckerath — IBN 1-IT, Forschungszentrum Jülich, 52425 Jülich

The dielectric SiO₂ has been the key to the tremendous improvements in Si-based metal-oxide-semiconductor (MOS) device performance over the past four decades. It has, however, reached its limit in terms of scaling since it exhibits a leakage current density higher than 1 A/cm² and does not retain its intrinsic physical properties at thicknesses below 1.5 nm [1,2]. In order to overcome these problems and keep Moore’s law ongoing, the use of higher dielectric constant (k) gate oxides has been suggested. These high-k materials must satisfy numerous requirements such as the high k, low leakage currents, suitable band gap und offsets to silicon. Rare-earth based dielectrics are promising materials which fulfill these needs. We will review the properties of REScO₃ (RE = La, Dy, Gd, Sm, Tb) and LaLuO₃ thin films, grown with pulsed laser deposition, e-gun evaporation or molecular beam deposition, integrated in capacitors and transistors. A k > 20 for the REScO₃ (RE = Dy, Gd) and around 30 for (RE = La, Sm, Tb) and LaLuO₃ are obtained. Transistors prepared on SOI and sSOI show mobility values up to 380 cm²/Vs on sSOI, which are comparable to such prepared with HfO₂. [1] X. Gou, and T. P. Ma, IEEE Electron Device Lett. 19, 207 (1998). [2] D. A. Muller, T. Sorsch, S. Moccio, F. H. Baumann, K. Evans-Lutterodt, and G. Timp Nature 399, 758 (1999).