Characterization of the CeO₂ thin films for insulation layer and Pt/SrBi₂Ta₂O₉/CeO₂/Si MFISFET structure

CeO2 and SrBi2Ta2O9 (SBT) thin films for MFISFET (metal-fcrroelectrics- insulator-semiconductor field effect transistor) were deposited by rf sputtering and pulsed laser deposition method, respectively. The effects of oxygen partial pressure during deposition for CeO2 films were investigated. The oxygen partial pressure significantly affected the preferred orientation, grain size and electrical properties of CeO2 films. The CeO2 thin films with a (200) preferred orientation were deposited on Si(100) substrates at 600C. The films deposited under the oxygen partial pressure of 50 % showed the best C-V characteristics among those under various conditions. The leakage current density of films showed order of the 10-710-8 A/cm2 at 100 kV/cm. The SBT thin films on CeO2/Si substrate showed dense microstructure of polycrystalline phase. From the C-V characteristics of MFIS structure composed of the SBT film annealed at 800C, the memory window width was 0.9 V at 5 V. The leakage current density of Pt/SBT/CeO2/Si structure annealed at 800C was 410-7 A/cm2 at 5 V.