Barrier performance of ultrathin Ni-Ti film for integrating ferroelectric capacitors on Si

摘要

Ultrathin amorphous Ni-Ti film is investigated as conductive diffusion barrier layer to integrate La_(0.5)Sr_(0.5)CoO_3/PbZr_(0.4)Ti_(0.6)O3/La_(0.5)Sr_(0.5)CoO_3 (LSCO/PZT/LSCO) capacitors on silicon. X-ray photoelectron spectroscopy results demonstrate that Ni in LSCO/Ni-Ti/Si heterostructure is not oxidized after 550 ℃ annealing in oxygen. The structural properties of LSCO/PZT/LSCO/Ni-Ti/Si are characterized by x-ray diffraction and transmission electron microscopy. It is found that Ni-Ti film is still amorphous and that there are no discernible reactions at the interfaces of the sample. LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good ferroelectric properties, such as low coercive field (～1.28 V), high remnant polarization (～27.9 μC/cm~2), and good fatigue-free characteristic, implying that ultrathin amorphous Ni-Ti film can be used as barrier layer for fabricating high-density ferroelectric random access memories.