Novel ferroelectric epitaxial (Ba,Sr)TiO/sub 3/ capacitor for deep sub-micron memory applications

A novel ferroelectric capacitor cell was developed using a (Ba,Sr)TiO/sub 3/ (BSTO)/SrRuO/sub 3/ (SRO) heteroepitaxial technique on Si and strontium titanate substrates. Distinct ferroelectricity results from the c-axis being elongated due to lattice mismatch between the dielectric and electrode. The epitaxial BSTO capacitor showed distinct ferroelectricity even at 30 nm thickness, which is the thinnest ferroelectric film so far. Its superior ferroelectric properties, reliability, and sub-micron silicon process compatibility were confirmed.