Thermal Stability and Electrical properties of HfOxNy Gate Dielectrics with TaN Gate Electrode

Abstract

HfO2 and HfOxNy films were deposited by plasma-enhanced chemical vapor deposition using Hf[OC(CH3)3]4 as the precursor in the absence of O2. The crystallization temperature of the HfOxNy films is higher than that of the HfO2 film. Nitrogen incorporation in HfOxNy was confirmed by auger electron spectroscopy analysis. After post deposition annealing (PDA) at 800℃, the EOT increased from 1.34 to 1.6 nm in the HfO2 thin films, whereas the increase of EOT was suppressed to less than 0.02 nm in the HfOxNy. The leakage current density decreased from 0.18 to 0.012 A/cm2 with increasing PDA temperature in the HfO2 films. But the leakage current density of HfOxNy does not vary with increasing PDA temperature because an amorphous HfOxNy films suppresses the diffusion of oxygen through the gate dielectric.