The trend of replacing trench and stack capacitors in a dynamic random access memory (DRAM) with a planar configuration has stimulated the development of high dielectric constant materials with reliably low leakage current and high dielectric breakdown strength. In this regard, high dielectric constant materials, such as PbZrxTiyO3(PZT), BaTiO3, SrTiO3, PbTiO3, and BaxSr1-xTiO3, have been extensively investigated as dielectrics in the last few decades. Of these, the sol id-solution quaternary BaxSr1-xTiO3, (BST) combines the high dielectric constant of BaTiO3, with the structural stability of SrTiO3, is one of the most promising materials for DRAM cells in very large-scale integrated circuits. BST shows a paraelectric phase for x<0.7 at room temperature, which provides additional features such as no aging or fatigue effects from ferroelectric domain switching. However, so far, there have been few studies of the interfaces between BST and the substrates, particularly at the atomic-resolution level.
Characteristics of microstrip transmission lines with high-dielectric-constant substrates
