Regensburg 2010 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 7: Dielectric and ferroelectric thin films

DF 7.6: Vortrag

Dienstag, 23. März 2010, 15:40–16:00, H11

CaTiO₃ as a high-k dielectric in thin MIM Capacitor stacks — •Andreas Krause¹, Walter M. Weber¹, Andreas Jahn², Ulrich Merkel², Matthias Albert², Uwe Schroeder¹, Johann W. Bartha², and Thomas Mikolajick¹ — ¹namlab gGmbh, D-01187 Dresden — ²Institut fuer Halbleiter- und Mikroelektronik IHM, TU Dresden

With the further increase in integration density of microelectronics, ordinary SiO₂-based dielectrics reach their limits as leakage currents increase significantly. Therefore, dielectric materials are required that combine a high dielectric constant (k) and low leakage currents. Metal Insulator Metal (MIM) stacks with the perovskite calcium titantate (CaTiO₃) as a high-k oxide were sputter deposited with variing thicknesses and deposition temperatures. As electrodes, different work function materials were used: Pt, Ru, TaSiN, TiN. Optimizing the roughness and deposition parameters of the electrodes, a k-value of 51 is reached with a capacitance equivalent thickness targeting 1nm. The leakage currents for 15 nm thick CaTiO₃ films are about 1 · 10⁻⁷ A/cm² at 1 V, which is in agreement with the ITRS roadmap of 2013. The morphology was studied with atomic force microscopy and scanning electron microscopy. Capacitor-voltage measurements were performed to extract the k-value. In addition, the crystallinity of the oxide and metal electrode was investigated with variable temperature x-ray defraction measurements, showing clearly the transition from the amorphous to the crystal state in dependence of the temperature.