INTERMEDIATE AMORPHOUS LAYER FORMATION MECHANISM AT THE INTERFACE OF EPITAXIAL CEO2 LAYERS AND SI SUBSTRATES

The formation mechanism of an intermediate amorphous layer between epi taxially grown CeO2 layers and silicon substrates is studied using cro ss-sectional transmission electron microscopy and Auger electron spect roscopy. The intermediate amorphous layer thickness increases after an nealing at 800-degrees-C in air, whereas it decreases somewhat after a nnealing in an ultrahigh vacuum. Auger in-depth analysis verifies that the intermediate amorphous layer is silicon dioxide. The intermediate oxide growth of the CeO2/Si structures due to intentional oxidation a t 700 approximately 900-degrees-C in a dry oxygen ambient is analyzed and the results indicate that the oxidation proceeds in an intermediat e step between reaction limited and diffusion limited processes. The i ntermediate amorphous layer formation mechanism is concluded to be oxy gen diffusion through CeO2 layers and successive oxidation of silicon at the interface.