(Pb, La)(Zr, Ti)O3 film grain-boundary conduction with SrRuO3 top electrodes

The relationship between Sr interdiffusion from a Pt/SrRuO3 [SRO] top electrode into (Pb, La)(Zr, Ti)O-3 [PLZT] ferroelectric thin films with different excess Pb contents (2-10%) and leakage properties was studied. Secondary ion mass spectrometry and energy dispersive X-ray spectroscopy revealed significant Sr diffusion into the PLZT film after annealing, which increased with increasing excess Ph content. The diffused Sr existed in the PLZT crystalline grain boundaries, but not in the grains. The high leakage was attributed to a low resistance compound Sr-Pb-O in the PLZT grain boundaries. To obtain low leakage SRO/PLZT capacitors, it is necessary to eliminate the Sr-Pb-O grain boundary phase by lowering the excess Pb content to 7% or less.