Composition, atomic transport, and chemical stability of ZrAl/sub x/O/sub y/ ultrathin films deposited on Si(001)

Abstract

The stability of a ZrAlxOy film sputtered on Si upon thermal annealing in vacuum or in O2 was investigated. X-ray diffraction indicated that the as-deposited film was amorphous and remained so after annealing. Rutherford backscattering, narrow nuclear resonance profiling, and low-energy ion scattering provided the average composition of the film and the depth distributions of different elements. Chemical analysis of these elements was accessed by x-ray photoelectron spectroscopy. Annealing in vacuum produced thickness inhomogeneities and/or transport of very small amounts of Si from the substrate into the overlying film, with formation of Si precipitates. Annealing in O2 led to oxygen exchange throughout the film, as well as Si transport in slightly higher amounts than in vacuum. Differently from the observed upon annealing in vacuum, Si was either incorporated into the Zr,Al–O framework or oxidized in SiO2.