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DF: Fachverband Dielektrische Festkörper
DF 9: High-k and Low-k Dielectrics (Joint Session of DS, DF)
DF 9.5: Talk
Tuesday, March 15, 2011, 14:45–15:00, GER 38
Local I-V characteristics of high-k ultra-thin ZrO2- and ZrO2/Al2O3/ZrO2-films. — •Dominik Martin1, Matthias Grube1, Elke Erben1, Johannes Müller2, Wenke Weinreich2, Uwe Schroeder1, Lutz Geelhaar3, Walter Weber1, Thomas Mikolajick1,4, and Henning Riechert3 — 1namlab Gmbh, D-01187 Dresden — 2Fraunhofer-CNT, D-01099 Dresden — 3Paul-Drude-Institut für Festkörperelektronik, D-10117 Berlin — 4Chair of Nanoelectronic Materials, 01062 Dresden, Germany
In order to produce ultra thin ZrO2-films, with a dielectric constant high enough to satisfy industry demands, it is necessary to reach the tetragonal crystalline phase. This can be achieved either by high temperature deposition or by a post deposition annealing step. Both however induce high leakage currents. Small amounts of Al2O3 can be incorporated in ZrO2 to reduce leakage current. To get more insight into the charge carrier transport mechanisms involved, a thickness series of ultra thin ZrO2- and ZrO2/Al2O3/ZrO2-films were deposited by ALD and subjected to different rapid thermal annealing processes. These layers were examined by GI-XRD, TEM, I-V-, C-V-Spectroscopy and conductive atomic force microscopy. Thus, leakage currents are reduced to 3.2·10 −8A/cm2 at 1 V while maintaining the high k value (CET=1 nm at 1V for a 10 nm film) . CAFM studies demonstrate how the crystallization effects the charge transport mechanisms on the mesoscopic scale. Local I-V curves acquired on amorphous films and at grain boundaries in nanocrystalline films in yield lower breakdown voltages and higher leakage currents at crystallite grain boundaries.