Properties of HfAlO film deposited by plasma enhanced atomic layer deposition

Abstract

Plasma enhanced atomic layer deposition (PEALD) method can reduce film growing temperature, and allow in situ plasma treatment. In this work, HfAlO and HfO2 films were deposited with PEALD at 160°C. Microstructure analysis showed that both films were amorphous after rapid thermal annealing (RTA) treatment, and HfAlO sample showed better interfacial structure than HfO2. X-ray photoelectron spectroscopy (XPS) spectra indicated that main component of the interfacial layer of HfAlO sample was Hf–Si–O and Al–Si–O bonds, the valence band offset value between the HfAlO film and Si substrate was calculated to be 2.5eV. The dominant leakage current mechanism of the samples was Schottky emission at a low electric field (<1.4MV/cm), and Poole–Frenkel emission mechanism at a higher electric field (>1.4MV/cm). The equivalent oxide thicknesses (EOT) of the HfAlO samples were 1.0nm and 1.3nm, respectively. The density of interface states between dielectric and substrate were calculated to be 1.2×1012eV−1cm−2 and 1.3×1012eV−1cm−2, respectively. In comparison with HfO2 film, HfAlO film has good interfacial structure and electrical performance.