Characterization of Al Incorporation into HfO Dielectric by Atomic Layer Deposition.

This study presents the characteristics of HfAlO films for a series of Al incorporation ratios into a HfO dielectric by atomic layer deposition on a Si substrate. A small amount of Al doping into the HfO film can stabilize the tetragonal phase of the HfO, which helps to achieve a higher dielectric constant () and lower leakage current density, as well as a higher breakdown voltage than HfO film on its own. Moreover, assimilation of AlO into HfO can reduce the hysteresis width and frequency dispersion. These are indications of border trap reduction, which was also verified by the border trap extraction mechanism. X-ray photoelectron spectroscopy (XPS) analysis also verified the HfAlO microstructural properties for various Al compositions. In addition, higher amounts of AlO in HfAlO resulted in better interface and dielectric behavior through trap minimization, although the equivalent-oxide-thickness (EOT) values show the opposite trend.