Preparation of BST thin films on Pt electrode on Si wafer with down-flow LSMCVD reactor

Abstract

A novel type of down-flow LSMCVD (Liquid Source Mist CVD) reactor was developed to prepare a high dielectric BST thin film on Pt electrode on Si wafer. Barium acetate [Ba(00CCH(3))(2)], strontium acetate [Sr(00CCH(3))(2)], and titanium isoproxide [Ti(OC3H7i)(4)] were used as metal sources. Metal sources were dissolved in acetic acid, 1-butanol, or 2-methoxyethanol. BST [Ba/(Ba + Sr) = 0.7] film annealed on Pr/Ti/SiO2/Si above 650 degrees C was polycrystalline. BST film has a (110) preferred orientation with increasing temperature. Surface roughness of BST film and grain size increased with increasing temperature. The metal-oxygen bond was formed at 650 degrees C as shown in the spectra of FTIR. The depth profiles of elements of BST thin films indicated a uniform composition throughout the film, BST films annealed at 750 degrees C showed a dielectric constant and a tans of 390(thickness: 150 nm) and 0.06 at a frequency of 100 kHz, respectively. The behavior of capacitance of the BST film with bias voltage showed paraelectric property. BST film annealed at 750 degrees C had the leakage current density of 3.2(mu A/cm(2)) at a bias voltage of 2V.