Electrical properties of highly reliable plug buffer layer for high-density ferroelectric memory

A CoSi2 buffer layer was prepared in polycrystalline silicon (polysilicon) plug for preventing an undesired microvoid between the polysilicon plug and Ir/Ti diffusion barrier. Since the microvoid generates random function fail, resulting in low wafer yield of a 4 Mb ferroelectric random access memory device, we developed the thermally stable CoSi2 buffer layer for eliminating the random single bit fails. The ferroelectric capacitors using the CoSi2 buffer layer showed a low contact resistance of 96 Omega per contact in 1k serial contact array with contact size of 0.6 mum, and also exhibited great ferroelectric properties such as remnant polarization and coercive voltage of 20 muC/cm(2) and 1.2 V, respectively. Scanning electron microscopy analyses confirmed that no microvoid was formed between the interface between the Ir/Ti barrier layer and the CoSi2 buffer layer. (C) 2002 American Institute of Physics.