STUDY OF PT BOTTOM ELECTRODES USING HIGH-TEMPERATURE SPUTTERING FOR FERROELECTRIC MEMORIES WITH SRBI2TA2O9 (SBTO) FILM

Pt bottom electrodes for SrBi2Ta2O9 (SBTO) capacitors have been invest igated for use in nonvolatile memories. A Pt thin film which is sputte red at a temperature of 300 degrees C consists of enlarged columnar gr ains, while a film sputtered at room temperature consists of fibrous c olumnar rains. The formation mechanism of enlarged grains of the Pt fi lm sputtered at 300 degrees C is dire to the fact that the film struct ure changes with substrate temperature based on the structure-zone mod el. The Pt bottom electrode which consists of the enlarged grains resu lts in a decrease in the Ti diffusion path, leading to effective adhes ion of Pt to a SiO2 film.