Integration of perovskite oxide dielectrics into complementary metal-oxide-semiconductor capacitor structures using amorphous TaSiN as oxygen diffusion barrier

摘要

The high permittivity perovskite oxides have been intensively investigated for their possible application as dielectric materials for stacked capacitors in dynamic random access memory circuits. For the integration of such oxide materials into the CMOS world, a conductive diffusion barrier is indispensable. An optimized stack p(++)-Si/Pt/Ta21Si57N21/Ir was developed and used as the bottom electrode for the oxide dielectric. The amorphous TaSiN film as oxygen diffusion barrier showed excellent conductive properties and a good thermal stability up to 700 degrees C in oxygen ambient. The additional protective iridium layer improved the surface roughness after annealing. A 100-nm-thick (Ba,Sr) TiO3 film was deposited using pulsed laser deposition at 550 degrees C, showing very promising properties for application; the maximum relative dielectric constant at zero field is k approximate to 470, and the leakage current density is below 10(-6) A/cm(2) for fields lower then +/- 200 kV/cm, corresponding to an applied voltage of +/- 2 V. (C) 2011 American Institute of Physics. [doi:10.1063/1.3641636]