Characterization of Mis Capacitor of Bst Thin Films Deposited on Si by Rf Magnetron Sputtering

Abstract

AbstractThe application of high dielectric (Ba, Sr)TiO3 [BST] thin films for Metal-Insulator- Semiconductor(MIS) capacitors was investigated. BST thin films were deposited on p-Si(100) substrates by the RF magnetron sputtering with temperature range of 500–600 °C. We examined the characteristics of MIS capacitor with various oxygen pressure, substrate temperature and (Ba+Sr)/Ti ratio. The dielectric properties of MIS capacitors consisting of AI/BST/SiO2/Si sandwich structure were measured for various conditions. The charge state densities of the MIS capacitors were determined by high frequency (1 MHz) C-V measurement. Also, current-voltage characteristics of the MIS capacitor were investigated. In order to reduce the leakage current in MIS capacitor, high quality SiO2 layer was grown on bare p-Si substrate by thermal oxidation. By applying SiO2 layer between BST thin films and Si substrate, low leakage current of 10−10 order was observed. Futhermore, the leakage current showed the dependence on the oxygen concentration in plasma gas and the (Ba+Sr)/Ti ratio. Also, the BST MIS structure showed relatively high capacitance even though it is the combination of high-dielectric BST thin films and SiO2 layer. By C-V measurement, the polarity of effective oxide charge changed with the oxygen concentration in plasma gas and (Ba+Sr)/Ti ratio of sputtering target.