Charles Dornfest

Sub-300 Å (Bax,Sr1-x)TiO3 films by metal organic chemical vapor deposition: Nanostructure, step coverage, and dielectric properties

This is a preliminary report on the nanostructure and its evolution, step-coverage, and dielectric properties of sub-300 A (Bax,Sr1-x)TiO3 films. The (001)-oriented polycrystalline films were deposited at 50–70 A/min by metal-organic chemical vapor deposition (MOCVD) on (111) Pt-passivated Si substrates of 8-inch diameter. From the detailed nonstructural characterization of (Ba0.64,Sr0.36)TiO3 films, the orientation, cation stoichiometry, and an alternative but plausible mechanism of growth and the origin of roughness are forwarded. Additionally, the step-coverage in 2:1 to 5:1 aspect-ratio trenches, coupled with the frequency/voltage dependence of the dielectric properties of (Bax,Sr1-x)TiO3 films are reported. A 275 A (Ba0.64,Sr0.36)TiO3 film exhibited a dispersionless dielectric permittivity and loss tangent of 260 and 0.003, respectively, and the permittivity (er=340) of a 300 A (Ba0.5,Sr0.5)TiO3 film reduced by 53% at a dc-bias of 3 V.