Analysis of chemical bond states and electrical properties of stacked AlON/HfO2 gate oxides formed by using a layer-by-layer technique

Abstract

Stacked AlON/HfO2 thin films for gate oxides in metal-oxide-semiconductor devices are successfully prepared on Si substrates by utilizing a layer-by-layer technique integrated with an off-axis RF remote plasma sputtering process at room temperature. This off-axis structure is designed to improve the uniformity and the quality of gate oxide films. Also, a layer-by-layer technique is used to control the interface layer between the gate oxide and the Si substrate. The electrical properties of our stacked films are characterized by using capacitance versus voltage and leakage current versus voltage measurements. The stacked AlON/HfO2 gate oxide exhibits a low leakage current of about 10(-6) A/cm(2) and a high dielectric constant value of 14.26 by effectively suppressing the interface layer between gate oxide and Si substrate. In addition, the chemical bond states and the optimum thickness of each AlON and HfO2 thin film are analyzed using X-ray photoemission spectroscopy and transmission electron microscopy measurement.