HfO2Film Formation Combined with Radical Nitridation and Its Electrical Characteristic

A HfON/SiN gate dielectric was prepared using a radical nitridation method. Nitrogen incorporation into HfO2 was confirmed by X-ray photoelectron spectroscopy analysis. The HfON/SiN gate dielectric showed a smaller change in capacitance equivalent oxide thickness (CET) after rapid thermal oxidation (RTO) and a lower leakage current density (J) than those of HfO2 and HfO2/SiN with the same physical thickness. Even after RTO at 700°C for 30 s, a CET of 1.5 nm with J of 2×10-5 A/cm2 at (VFB-1) V was obtained, where VFB is the flat-band voltage. This improvement of the HfON/SiN gate dielectric can be explained by the presence of Si-N bonds at the HfO2/Si-substrate interface and Hf-N bonds in the HfO2 film. These nitrogen bonds strengthen the immunity to oxygen diffusion and improve leakage current characteristics.