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O: Fachverband Oberflächenphysik
O 10: Oxides and insulators II
O 10.5: Talk
Monday, March 23, 2009, 16:00–16:15, SCH A01
C-AFM characterization of high-k dielectric films grown by molecular beam deposition — •Peter Dudek, Jarek Dabrowski, Grzegorz Kozlowski, Grzegorz Lupina, Gunther Lippert, and Hans-Joachim Müssig — IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) / Germany
Very thin high-k dielectric films (thickness below 10 nm, dielectric constant k around 100) deposited on metallic electrodes are of particular interest for dynamic random access memories (DRAM). High capacitance density of storage capacitors must be accompanied by extremely low leakage currents: leakage should not exceed about 10−8 A/cm2 at bias around 0.5 V. This study uses conductive atomic force microscopy (C-AFM) to investigate microscopic aspects of electron transport across group-II hafnate and zirconate films deposited by MBE. Typically, most leakage is confined to nano-sized ,,hot spots”. Analysis of hot spot IV characteristics, including their statistical distribution, provides insight into leakage mechanisms. This analysis is guided by quantum-mechanical simulations for trap-assisted tunnelling and ab initio calculations for the formation energies and electronic structures of point defects. Among the effects discussed in this work is local resistivity switching. We also present the first data obtained for dielectric perovskite films with intentional admixture of TiO, whereby the influence of substrate electrode (TiN, Ru, or Pt) is considered.