The hole-trapping and electron-trapping characteristics in dry oxides following various chemical cleanings have been studied using the avalanche injection method. The results indicated that hole trap density was almost the same for the chemical cleanings. Electron traps with two capture cross sections, σ, were observed. Electron traps with σ210-17 cm2 were found to be independent of the chemical cleaning, while those with σ410-19 cm2 to depend on the cleaning. Comparison with previous works indicated that electron traps with larger σ were related to Si-OH bonds. The other electron trap showed the increasing trapping rate with increasing the current density injected into oxide. This was explained by trap generation due to electron injection. A correlation between the density of generated electron traps and the amount of Al contamination on surfaces before dry oxidation was observed.

A new test structure to specify accurately the position of gate oxide breakdown is proposed, which simply consists of a conventional polycrystalline Si gate MOS capacitor and Al dots array diagonally lined-up on the capacitor. Optical beam induced current microscope was used to discriminate the breakdown spot. Layout of the discriminated spot among the Al dot array accurately determined the breakdown position. A 5-nm-thick gate oxide breakdown spot determined by this method has been successfully investigated by cross-sectional transmission electron microscopy (XTEM). A series of site-specified XTEM studies reveal local melting of anode Si during the intrinsic dielectric breakdown. This test structure is practically useful for site-specified XTEM studies on process-induced degradation phenomena of thin gate oxides.