Effects of chamber pressure on composition and electrical properties of Zr-modified (Ba_1-x, Sr_x)TiO₃ thin films grown by sputtering

Zr-modified (Ba_1-x, Sr_x)TiO₃ thin films as capacitors for high density dynamic random access memory were deposited by r.f. magnetron sputtering as a function of chamber pressure. The Zr/Ti ratio of films increased significantly with decreasing chamber pressure and this variation affected the microstructure and surface roughness of the films. The dielectric constant of the films increased due to the decrease of Zr when chamber pressure was increased. The (Ba_1-x, Sr_x)(Ti_1-y, Zr_y)O₃ thin films showed a dielectric constant of 380 to approximately 525 at 100 kHz. The leakage current exhibited a smaller value as chamber pressure decreased and the leakage current density of films with various Zr contents was order of the 10^-7-10^-9 A/cm² at 200 kV/cm.