Comparison of electrical properties of thin calcium titanate high-k insulators on RuO2, Pt and C electrodes

Using radio frequency sputtering, CaTiO3 layers with varying thicknesses and deposition temperatures are deposited on different bottom electrodes. On elevated temperatures, the CaTiO3 layer growth and therefore the properties like crystallinity and leakage current depend strongly on the morphology and lattice constant of the bottom layer. With the use of temperature stable bottom electrodes, which are deposited prior to the oxide deposition without any vacuum break, like Pt on PVD TiN and Pt on RuO2, an improvement to the k-value as well as the leakage current is achieved compared to CVD -TiN/ Pt stacks. In addition, a pyrolytic C electrode is used the first time in a metal-insulator-metal capacitor for DRAM applications. Keywords—Dielectrics, High-k, CaTiO3, MIM capacitor