Study of Pt Bottom Electrodes using High-Temperature Sputtering for Ferroelectric Memories with SrBi 2 Ta 2 O 9 (SBTO) Film

Pt bottom electrodes for SrBi 2 Ta 2 O 9 (SBTO) capacitors have been investigated for use in nonvolatile memories. A Pt thin film which is sputtered at a temperature of 300°C consists of enlarged columnar grains, while a film sputtered at room temperature consists of fibrous columnar grains. The formation mechanism of enlarged grains of the Pt film sputtered at 300°C is due to the fact that the film structure changes with substrate temperature based on the structure-zone model. The Pt bottom electrode which consists of the enlarged grains results in a decrease in the Ti diffusion path, leading to effective adhesion of Pt to a SiO 2 film.