Spectroscopic evidence for a network structure in plasma-deposited Ta2O5 films for microelectronic applications

Based on the bond-ionicity definition of Pauling, gate dielectric materials are grouped into three categories with increasing bond ionicity, continuous random networks, crn's, modified crn's with ionic components, mcrn's, and random closed packed ionic structures, rcpis's. Using this classification scheme, fully oxidized Ta2O5 films prepared at low temperature, ∼300 deg. C, have mcrn's, and are expected to have similar bonding arrangements and thermal stability to non-crystalline Al2O3 and SiO2-rich, Zr silicate alloys. This is verified by combining previously published Raman data with more recent FTIR and EXAFS results