Thin film, high-k capacitors are processed via ALD (atomic layer deposition). At a temperature of 200 C, the deposition recipe realized rates of 0.97 and 0.95 °A/cycle for alumina and hafnia, respectively. 31.8 and 34.7 nm alumina and hafnia films were measured by ellipsometry to have refractive indices of 1.69 and 2.07. Capacitance-voltage tests confirmed dielectric constant values of 8.36 and 24.8 while current-voltage tests lead to the derivation of the following ranges for dielectric strength: 17.0-24.5 and 16.8-27.0 MV/cm for alumina and hafnia. The dielectric strength of alumina was found to be ˜100x that dictated in literature. The dielectric strength of hafnia was found to be about half that reported. The discrepancy in values could be an indication of nonstoichiometric dielectrics, recipe/processing variation, and/or sintering effects.
"Fabrication and Characterization of High-k Al2O3 and HfO2 Capacitors,"
Journal of the Microelectronic Engineering Conference: Vol. 24
, Article 28.
Available at: https://scholarworks.rit.edu/ritamec/vol24/iss1/28