Dielectric property and thermal stability of HfO2 on silicon

Abstract

A stoichiometric, uniform, and amorphous hafnium oxide thin film is deposited by an atomic layer deposition process. The as-deposited hafnium oxide films showed superior electrical properties compared to zirconium oxides, including a dielectric constant of 23, a flatband voltage shift of +0.3 V, a hysteresis of 25 mV, an interfacial trap density of 1.8×1011 cm−2 eV−1, and a leakage current density several orders of magnitude lower than SiO2 at an equivalent oxide thickness of 9.3 Å, suitable for metal–oxide–semiconductor device applications. The thermal stability of hafnium oxide on silicon was determined to be better than that of zirconium oxide. Post-deposition annealing in oxygen and ammonia further improved the thermal stability of HfO2 to 1000 and 1100 °C, respectively.