ECR-MOCVD of the Ba-Sr-Ti-O system below 400°C. Part I: Processing

SrTiO 3 (or ST) and (Ba, Sr)TiO 3 (or BST) thin films were deposited on Pt passivated Si substrates below 400°C, using β-diketonates of Ba, Sr, and Ti, electron cyclotron resonance (ECR) plasma-enhanced chemical vapor deposition (CVD), and direct liquid injection system. Reported here are results from various thin-film characterization techniques including TEM and SEM. To optimize the processing parameters with respect to phase purity, Sr/Ti ratio, and permittivity, the method of design of experiments was implemented. The as-deposited (at 390°C), unannealed ST films exhibited a permittivity of 120 and an ohmic contact with the bottom Pt electrode. The former was attributed to the small grain size (150-200 å) and presence of Sr rich second phases. The latter was related to the observed incubation period at the initial nucleation stages of film growth.