Impact of post-deposition annealing on RF sputtered calcium copper titanate thin film for memory application

Calcium copper titanate (CCTO) sputtering target was synthesized by solid state method. Structural analysis of target has confirmed the formation of CCTO phase. CCTO thin films were deposited by RF magnetron sputtering technique on p-Si (100) substrates with the working pressure and RF power of 5 × 10^–3 mbar and 105 W, respectively. Post-deposition annealing was performed at different temperatures ranging from 650 °C to 950 °C. Evolution of CCTO polycrystalline peaks has been observed in the 950 °C annealed film. The formation of CCTO phase has also been confirmed by FTIR spectroscopy studies. The surface morphology of the annealed thin film was found to be modulated with the annealing temperature. Larger microstructures have been found for the films annealed at high temperature. Bandgap of films were calculated from UV–vis spectral analysis. Electrical properties of the annealed thin films were studied by fabricating Al/CCTO/Si MOS structures. The interface trap density (D_it) was calculated as 7.9 × 10¹⁰ eV⁻¹ cm⁻² for the films annealed at 950 °C. Improved bipolar resistive switching behavior has been observed for the films annealed at 950 °C. (paper)