Impacts of Ti content and annealing temperature on electrical properties of Si MOS capacitors with HfTiON gate dielectric

HfTiON gate dielectric is fabricated by reactive co-sputtering method followed by annealing in N₂ ambient. The effects of Ti content and annealing temperature on the performances of HfTiON gate-dielectric Si MOS devices are investigated. Experimental results indicate that gate capacitance is increased with increasing Ti content. However, when the Ti/Hf ratio exceeds ~1.75, increase of the gate capacitance becomes small. Surface roughness of the samples annealed at different temperatures is analyzed by AFM, and results show that high annealing temperature (e.g. 700°C for 30 s) can produce smooth surface, thus resulting in low gate leakage current.