Characteristics of metal-insulator-semiconductor capacitors based on high-k HfAlO dielectric films obtained by low-temperature electron-beam gun evaporation

We describe the characteristics of thin HfAlO films deposited at low temperature by electron beam gun evaporation. As-deposited films thinner than 6 nm exhibit an effective dielectric constant (keff) of 9–11.5. The minimum quantum mechanical corrected effective oxide thickness is ∼1.45nm and the leakage currents are very low. Rapid thermal annealing in a N2 environment improves the leakage further and up to 750 °C does not affect keff. Higher annealing temperatures reduce keff, but even at 950 °C, it has a value of 6.5. These HfAlO films have the potential to serve as a substitute for SiO2 in small-scale metal-insulator-semiconductor structures.