Effect of N2/Ar flow ratio on the structural and electrical properties of SrHfON thin films prepared by magnetron sputtering

• Novel high-k gate dielectric of SrHfON films were prepared by reactive co-sputtering.
• The properties of the SrHfON films as a function of N2/Ar flow ratio were presented.
• Effect of N2/Ar flow ratio on the properties of the SrHfON films was discussed.

SrHfON thin films were prepared by radio frequency (RF) magnetron reactive co-sputtering under various N2/Ar flow ratio in the range from 0.20 to 0.50. The effect of N2/Ar flow ratio on the deposition rate, composition, structure and electrical properties of the sputtered SrHfON films has been investigated using X-ray spectroscopy (XPS), grazing incidence X-ray diffraction (GI-XRD), leakage current density–voltage (J-V) and capacitance–voltage (C–V) measurements. The results show that the properties of the SrHfON films were greatly affected by the N2/Ar flow ratio. The deposition rate of the SrHfON films was found to decrease with the increasing N2/Ar flow ratio. The SrHfON films exhibited local crystallization when the N2/Ar flow ratio is low (<0.33) while the SrHfON films were amorphous when the N2/Ar flow ratio is high (>0.33). The average leakage current density of the SrHfON films decreases initially and then increases with the increasing N2/Ar flow ratio. Contrarily, the dielectric constant (k) of the SrHfON films increases firstly and then decrease with the increasing N2/Ar flow ratio. Moreover, both the flat-band voltage shift and fixed positive charge densities were decreased initially and then increased with the increase of N2/Ar flow ratio.