| Summary: | 碩士 === 明志科技大學 === 材料工程研究所 === 100 === Metal-ferroelectric (Nd and Zr-doped BiFeO3)-insulator (HfO2)- semiconductor (MFIS) structures have been fabricated by co-sputtering technique. The crystalline phase of ferroelectric film was identified by x-ray diffraction (XRD) pattern. The surface morphology was examined by the atomic force microscopy (AFM) with different processes. The microstructure and MFIS cross-section were characterized by TEM. The atom percentage at each region was analyzed by EDS.
The BFO:Nd film was found to be a perovskite structure. With increasing the postannealing temperature to 700℃, besides BFO phase, NdFeO3 phases were also observed. It indicates that the Bi3+ ion substituted by Nd3+ ion at higher annealing temperature. Also the BFO:Zr film was detected to be a perovskite structure. With increasing the postannealing temperature to 700℃, besides BFO phase, Bi2Fe4O9 phase was also observed. It indicates that the Fe3+ substituted by Zr4+ ion at higher annealing temperature. The microstructure of ferroelectric thin-film/insulator layer/silicon substrate was characterized by TEM and EDS mapping. With the insertion of insulator layer, the inter-diffusion of Fe, Bi, and Si were suppressed.
The memory windows of Al/BFO:Nd/HfO2/Si capacitors as functions of Ar/O2 ratio, DC power for Nd and insulator film thickness were measured. The maximum memory window of 1.609 V was obtained at the sweep voltage of 8 V with DC power of 15 W for Nd. On the other hand, the maximum memory window of 1.674 V was obtained at the sweep voltage of 8 V with DC power of 15 W for Zr.
|
|---|
