Deposition of high dielectric (Ba,Sr)TiO3 thin films by RF magnetron co-sputtering

This study investigates the characteristics of BST films deposited by rf ma gnetron co-sputtering of BaTiO3 and SrTiO3 targets. BST Films were prepared on four types of substrates at deposition temperatures ranging from 250 de greesC to 450 degreesC. The four substrates included Pt/Ti/SiO2/Si. Pt/Ta/S iO2/Si, Mo/SiO2/Si. and W/SiO2/Si. The dielectric constant and the leakage current density of BST films deposited on Pt/Ti/SiO2/Si substrates were hig her than other substrates in the absence of oxygen. Introducing oxygen redu ced the leakage current density as a consequence of the few oxygen vacancy and small surface roughness. The dielectric constant of 348 and leakage cur rent density of 1.2x10(-7) A/cm(2) at IV were obtained in the 160nm-thick B ST film deposited on Pt/Ti/SiO2/Si substrates at a deposition temperature o f 450 degreesC with a O-2:Ar=2:40 gas ratio. The co-sputtering method can o btain high quality BST films at a deposition temperature of 450 degreesC.