Pulsed laser deposited ZrAlON films for high-k gate dielectric applications

ZrAlON films were fabricated using the reactive ablation of a ceramic ZrAlO target in N-2 ambient by pulsed laser deposition (PLD) technique. ZrAlON films were deposited directly on n-Si(100) substrates and Pt coated silicon substrates, respectively, at 500 degrees C in a 20 Pa N-2 ambient, and rapid thermal annealed (RTA) in N-2 ambient at 1000 degrees C for 1 min. Cross sectional high-resolution transmission electron microscopy (HRTEM) images clearly show that the ZrAlON/Si interface is atomically sharp without an interfacial layer, and the films are completely amorphous. The electron diffraction pattern of TEM also indicates the amorphous structure of the RTA ZrAlON film. X-ray photoelectron spectroscopy (XPS) measurement was performed to confirm the effective incorporation of nitrogen with a content of about 6 at. %, and to reveal the N-O bonding in ZrAlON films. The dielectric constant of amorphous ZrAlON was determined to be about 18.2 which is more than 16.8 for ZrAlO by measuring the Pt/films/Pt capacitors. Capacitance-voltage (C-V) measurements show that a small equivalent oxide thickness (EOT) of 1.03 nm for 4 nm ZrAlON film on the n-Si substrate with a leakage current of 28.7 mA/cm(2) at 1 V gate voltage was obtained.