Physical and electrical characteristics of HfN gate electrode for advanced MOS devices

In this letter, the physical and electrical properties of physical vapor deposited (PVD) hafnium nitride (HfN) is studied for the first time as the metal gate electrode for advanced MOS devices applications. It is found that HfN possesses a midgap work function in tantalum nitride (TaN)/HfN/SiO2/Si MOS structures. TaN/HfN stacked metal-gated MOS capacitors exhibit negligible variations on equivalent oxide thickness (EOT), leakage current, and work function upon high-temperature treatments (up to 1000degreesC), demonstrating the excellent thermal stability of HfN metal gate on SiO2. Our results suggest that HfN metal electrode is an ideal candidate for the fully depleted SOI and/or symmetric double gate MOS devices application.