Thermal stability and dielectric properties of ultrathin CaZrOx films prepared by pulsed laser deposition

The thermal stability and dielectric properties of amorphous CaZrOx film prepared by pulsed laser deposition (PLD) have been investigated. X-ray diffraction (XRD) investigation shows that CaZrOx film still remains amorphous after rapid thermal annealing at 700 °C for 10 min. Differential thermal analysis (DTA) indicates that the crystallization temperature of CaZrOx film is about 729.53 °C, which is significantly higher than that of amorphous ZrO2 films prepared at the similar conditions. High-resolution transmission electron microscopy (HRTEM) and X-ray photon spectroscopy (XPS) analysis reveal there exists a Si-O transition layer between the CaZrOx film and Si substrate. The permittivity of CaZrOx film is about 10.5 (at 1 MHz) by measuring a Pt/CaZrOx/Pt MIM structure. Under the optimized conditions, a small EOT=0.91 nm and a leakage current density of 125 mA/cm2 at 1 V gate voltage were obtained. The enhanced thermal stability and improved electrical characteristics suggest that the amorphous CaZrOx film may be an attractive gate dielectric alternative for next generation MOS field effect transistor applications.