Thermal stability and decomposition of the HfO[sub 2]–Al[sub 2]O[sub 3] laminate system.

The thermal stability of the HfO[sub 2]–Al[sub 2]O[sub 3] laminate gate stack grown by atomic layer chemical vapor deposition was investigated using medium-energy ion scattering spectroscopy and high-resolution x-ray photoelectron spectroscopy. The laminate structure was maintained up to 800 °C under ultrahigh vacuum conditions, while it was drastically degraded at 850 °C, resulting in silicide formation on the film surface. Dissociated oxygen in the Hf–Al-oxide preferentially diffuses out through the film and desorbing at the surface. Volatile SiO species and Al–O components desorb through the sample surface, while HfO[sub 2] contributes to Hf silicide formation on the film surface. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]