Effect of chemical oxide layers on platinum-enhanced oxidation of silicon

Si oxidation promoted by a platinum (Pt) overlayer has been investigated using x-ray photoelectron spectroscopy and synchrotron radiation ultraviolet photoelectron spectroscopy. Heat treatments of the specimens with 〈∼5-nm-Pt/0.5–1-nm-chemical oxide/Si(100)〉 structure at 300–400 °C increase the oxide thickness to 4–5 nm. The amounts of the suboxide species, a(Si+), a(Si2+), and a(Si3+), in the chemical oxide layers formed in hydrochloric acid (HCl) plus hydrogen peroxide (H2O2) are in the order of a(Si+)>a(Si2+)>a(Si3+), while those for the oxide layers formed in nitric acid (HNO3) have an order of a(Si3+)>a(Si2+)≈a(Si+). The amounts of the suboxide species in the former oxide layers are much higher than those in the latter oxide layers. These results indicate that the HNO3 oxide layers are more highly oxidized, probably resulting in a higher atomic density and a lower defect density. Although the initial chemical oxide layers formed in HCl+H2O2 are thinner than those grown in HNO3, the former oxide layer...