Low temperature preparation of perovskite oxide films by ECR sputtering assisted with microwave treatment

SrTiO3 (STO) and (Ba,Sr)TiO3 (BST) films were prepared on unheated substrates by mirror-confinement-type electron cyclotron resonance (MCECR) plasma sputtering. STO films deposited on Si substrates by Ar plasma were amorphous, whereas those on Pt/Ti/SiO2/Si substrates by Ar/O2 plasma were sufficiently crystallized in spite of a low substrate temperature below 450 K. Annealing by 28 GHz microwave irradiation was applied to amorphous STO films on Si substrates and amorphous BST films on Pt/Ti/SiO2/Si substrates to crystallize these films. With microwave annealing, these films were crystallized at lower temperatures than with electric furnace annealing. The dielectric constant of STO films on Pt/Ti/SiO2/Si substrates annealed by microwave irradiation at 573 K was approximately 260, which was nearly equal to the bulk value of STO. Microwave irradiation to these films is considered to be useful since it can reduce the annealing temperatures and improve the electrical property.