Evidence of aluminum silicate formation during chemical vapor deposition of amorphous Al2O3 thin films on Si(100)

Using narrow nuclear reaction resonance profiling, aluminum profiles are ob tained in similar to 3.5 nm Al2O3 films deposited by low temperature (< 400 degrees C) chemical vapor deposition on Si(100). Narrow nuclear resonance and Auger depth profiles show similar Al profiles for thicker (similar to 1 8 nm) films. The Al profile obtained on the thin film is consistent with a thin aluminum silicate layer, consisting of Al-O-Si bond units, between the silicon and Al2O3 layer. Transmission electron microscopy shows evidence f or a two-layer structure in Si/Al2O3/Al stacks, and x-ray photoelectron spe ctroscopy shows a peak in the Si 2p region near 102 eV, consistent with Al- O-Si units. The silicate layer is speculated to result from reactions betwe en silicon and hydroxyl groups formed on the surface during oxidation of th e adsorbed precursor. (C) 1999 American Institute of Physics. [S0003-6951(9 9)03451-8].