A heteroepitaxial MIM-Ta/sub 2/O/sub 5/ capacitor with enhanced dielectric constant for DRAMs of G-bit generation and beyond

We demonstrate a novel MIM capacitor with a heteroepitaxial Ta/sub 2/O/sub 5/ dielectric, the permittivity of which is as high as 50. The heteroepitaxy of Ta/sub 2/O/sub 5/ on the Ru electrode changes its crystal symmetry from a conventional orthorhombic system to a hexagonal one. One-dimensional Ta-O-Ta chains along the c-axis bring about delocalized electrons, large polarizability and thus enhanced permittivity. This technology is promising for the application of Ta/sub 2/O/sub 5/ to Gbit DRAMs, eliminating the need to use such exotic materials as BST and STO.