RuO2 Bottom Electrodes for Ferroelectric (Pb, La)(Zr, Ti)O3 Thin Films by Metalorganic Chemical Vapor Deposition

RuO2 thin films were grown on various substrates by metalorganic chemical vapor deposition (MOCVD) using Ru(C11H19O2)3. The films produced at 350° C in O2 had a tetragonal rutile structure and a resistivity of 60 µΩ cm with excellent adhesion. From the viewpoint of integrated device applications, lanthanum-modified lead zirconate titanate (PLZT) films were also prepared by MOCVD. The RuO2 films were found to serve as effective diffusion barriers for PLZT and MgO. Significant interdiffusion at RuO2/Si and RuO2/SiO2 interfaces occurred during the deposition of PLZT films, and annealing of RuO2 film considerably depressed the interface reactions. Ta2O5 film served as an excellent barrier against the interface reaction between RuO2 and Si. The dielectric and ferroelectric properties of PLZT thin films on the RuO2/MgO and RuO2/Ta2O5/Si substrates were superior compared to those observed with RuO2/Si and RuO2/SiO2/Si substrates.