Dresden 2006 – scientific programme

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DS: Dünne Schichten

DS 18: Thin semiconducting films

DS 18.3: Talk

Thursday, March 30, 2006, 10:00–10:15, GER 38

Preparation and characterization of rare earth scandate thin films for high-κ applications — •M. Wagner¹, T. Heeg¹, J. Schubert¹, C. Zhao², M. Caymax², St. Lenk¹, and S. Mantl¹ — ¹Institute of Thin Films and Interfaces and CNI, Research Centre Jülich, D-52425 Jülich, Germany — ²IMEC, Kapeldreef 75, B-3001 Leuven, Belgium

Rare earth scandate thin films (GdScO₃ and DyScO₃) were deposited on a native SiO₂ or HF last surface of (100) silicon substrates using either pulsed laser deposition or electron beam evaporation. The films were investigated by means of Rutherford backscattering spectrometry, high temperature X-ray diffractometry, X-ray reflectometry, transmission electron microscopy and atomic force microscopy. Capacitor stacks with metal contacts have been electrically characterized. With both deposition techniques stoichiometric amorphous films with smooth surfaces (roughness RMS < 1 Å) were achieved. The amorphous phase of the films proved to be stable up to 1000^∘C. The films grown by pulsed laser deposition revealed featureless C-V-curves with nearly no hysteresis and a κ-value around 20 extracted from a CET plot. An interfacial SiO₂ grown during deposition could be observed. Films grown by electron beam evaporation show nearly no interfacial layer. A dielectric constant of 23 was determined. Consequently, a CET value of 1.5 nm along with a low leakage current density of 2.5× 10⁻⁴ A/cm² could be achieved. The main advantage of the evaporation technique is that particulate free films can be homogeneously deposited over a wide area. A deviation of < 5% in film thickness over a 2"-wafer was obtained.