Excess silicon at the silicon nitride/thermal oxide interface in oxide-nitride-oxide structures

The chemical composition and structure of Si3N4/thermal (native and wet) SiO2 interface in oxide-nitride-oxide structures are studied by using secondary ion mass spectroscopy, electron energy loss spectroscopy (EELS) and Auger electron spectroscopy (AES) measurements. EELS and AES experiments show the existence of excess silicon at the Si3N4/thermal SiO2 interface. Excess silicon (Si-Si bonds) at Si3N4/SiO2 interface exists in the form of Si-rich silicon oxynitride. Numerical simulation of the Si-Si bond's electronic structure by using semiempirical quantum-chemical method (MINDO/3) shows that Si-Si defects act as either electron or hole traps. This result explains the abnormally large electron and hole capturing at this interface reported earlier. (C) 1999 American Institute of Physics. [S0021-8979(99)03418-0].