Contact resistance of newly proposed RuTiN and RuTiO diffusion barriers for future high-density memory capacitors

Abstract

We suggested a new design concept for the diffusion barrier in high-density memory capacitors. Both RuTiN and RuTiO were proposed as sacrificial diffusion barriers for oxygen. For newly developed RuTiN and RuTiO barriers, oxidation resistance was superior to that of polycrystalline nitride and ternary amorphous barriers reported by others. Moreover, contact resistance, the most important electrical parameter for diffusion barriers in a capacitor structure, was below 5 kΩ for the Pt/barriers/TiSix/n++poly-Si plug/n+ channel layer/Si substrates even after annealing up to 750 °C, although the current–voltage curves showed nonlinear ohmic characteristics. Consequently, RuTiN and RuTiO films, as diffusion barriers for oxygen, were strongly recommended for achieving high-density capacitors.