Film thickness dependence of the dielectric properties of SrTiO3/BaTiO3 multilayer thin films deposited by double target RF magnetron sputtering

Four-layer SrTiO3/BaTiO3 thin films ((ST/BT)4) with various thicknesses deposited on Pt/Ti/SiO2/Si substrates at 500 °C by double target RF magnetron sputtering have been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), profilometry, capacitance–voltage and current–voltage measurements. The XRD patterns reveal the frame formation of the sputter deposited (ST/BT)4 with controlled modulation. The adhesion between the Pt bottom electrode layer and the BT layer is excellent. The dielectric constant of the (ST/BT)4 multilayer thin film increases with increasing film thickness. The effects of temperature, frequency, and bias voltage on the dielectric constant of the (ST/BT)4 multilayer thin films are discussed in detail. The leakage current density of the (ST/BT)4 multilayer with a thickness of 450.0 nm is lower than 1.0 × 10−8 A/cm2 for the applied voltage of less than 5 V, showing that the multilayer thin films with such a characteristic could be applied for use in dynamic random access memory (DRAMs) capacitors.