Barrier Performance of Various Thick Polycrystalline Ni-Al Films for Integrating PbZr0.4Ti0.6O3 Capacitors on Si

A diffusion barrier layer, separating two materials physically to prevent reaction or interdiffusion, is crucial for integrating ferroelectric capacitors with modern silicon transistor technology to realize high density ferroelectric random access memories. In the present study, various thicknesses of polycrystalline Ni-Al films, prepared by magnetron sputtering, are investigated as the oxygen diffusion barrier layers. Both Ni 2p(3/2) and Ni 2p(1/2) peaks increase, while NiO 2p(3/2) and NiO 2p(1/2) peaks decrease, with increasing depth from the interface between La0.5Sr0.5CoO3 and Ni-Al. Ni/(Al3+ + Ni2+) also increases with depth, indicating that the electrical conductivity of Ni-Al film annealed in oxygen increases with an increase in depth. La0.5Sr0.5CoO3/PbZr0.4Ti0.6O3/La0.5Sr0.5CoO3 ferroelectric capacitors fabricated on conducting silicon with Ni-Al film thicker than 60 nm, vertically characterized as the memory cells at 5 V, demonstrate very good physical properties, e. g., large remnant polarization 16-22 mu C/cm(2) and a relatively small leakage current density of similar to 2 x 10(-5) A/cm(2). (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3365060] All rights reserved.