Atomic Layer CVD in the Bi–Ti–O System

Thin films in the Bi–Ti–O system have, for the first time, been deposited by atomic layer CVD (ALCVD) using triphenyl bismuth, titanium isopropoxide, and water as precursors. The influence of the Bi:Ti precursor pulsing ratio at the deposition temperature of 260 °C and the influence of deposition temperature in the interval 200–325 °C were investigated. The growth rates of the films were about 0.2 Å/metal cycle, and the carbon content was less than 1.5 at.-%. The as-deposited films contained metallic bismuth but became amorphous upon annealing at 500 °C in air, and further annealing resulted in the formation of the dielectric Bi2Ti2O7 phase. The films annealed at 500 °C had permittivity values of around 60.