Enhanced dielectric properties of ZrO2 thin films prepared in nitrogen ambient by pulsed laser deposition

ZrO2 thin films were fabricated in O-2 ambient and in N-2 ambient by pulsed laser deposition (PLD), respectively. X-ray diffraction revealed that films prepared at 400degreesC remained amorphous. The dielectric properties of amorphous ZrO2 films were investigated by measuring the capacitance-frequency characteristics of Pt/ZrO2/Pt capacitor structures. The dielectric constant of the films deposited in N-2 ambient was larger than that of the films deposited in O-2 ambient. The dielectric loss was lower for films prepared in N-2 ambient. Atom force microscopy investigation indicated that films deposited in N-2 ambient had smoother surface than films deposited in O-2 ambient. Capacitance-voltage and current-voltage characteristics were studied. The equivalent oxide thickness (EOT) of films with 6.6 nm physical thickness deposited in N-2 ambient is lower than that of films deposited in O-2 ambient. An EOT of 1.38 nm for the film deposited in N-2 ambient was obtained, while the leakage current density was 94.6 mA cm(-2). Therefore, ZrO2 thins deposited in N-2 ambient have enhanced dielectric properties due to the incorporation of nitrogen which leads to the formation of Zr-doped nitride interfacial layer, and is suggested to be a potential material for alternative high-k (high dielectric constant) gate dielectric applications.