HfAlON films fabricated by pulsed laser ablation for high-k gate dielectric applications

HfAlON films were fabricated using the reactive ablation of a ceramic (HfO2)0.5(Al2O3)0.5 (i.e., HfAlO) target in N2 ambient by pulsed laser deposition (PLD) technique. HfAlON films were deposited directly on n-Si (100) substrates and Pt-coated silicon substrates, respectively, at 500 °C in a 20Pa-N2 ambient and rapid thermal annealed (RTA) in N2 ambient at 900-1000 °C. The electron diffraction pattern of transmission electron microscopy (TEM) indicates the amorphous structure of the HfAlON film RTA at 1000 °C. X-ray photoelectron spectroscopy (XPS) measurement was performed to confirm the effective incorporation of nitrogen with a content of about 5.28 at.% and to reveal the N-O bonding in HfAlON films. The dielectric constant of amorphous HfAlON was determined to be about 18.0, which is more than 16.6 for HfAlO by measuring the Pt/films/Pt capacitors. Capacitance-voltage (C-V) measurements show that a small equivalent oxide thickness (EOT) of 1.38 nm for 5-nm HfAlON film on the n-Si substrate with a leakage current of 12.5 mA/cm2 at 1-V gate voltage was obtained. High thermal stable HfAlON films with acceptable dielectric properties can be one of the most promising candidates for high-k gate dielectric applications.