The Si-SiO2 Interface Roughness: Causes and Effects

Abstract

The structural properties of silicon surfaces and interfaces have been studied from a macroscopic to an atomic scale by low energy electron diffraction (LEED), scanning tunneling microscopy (STM), and optical methids (lightscattering, magic mirror). The chemical state of silicon surfaces prepared by different cleaning procedures which influences the roughening was analyzed using x-ray photoelectron (XPS) and high resolution electron energy loss spectroscopy (HREELS) measurements. It is shown that thermal oxidation of silicon, in th4e course of device production, leads to a pronounced roughness at the Si-SiO2 interface. This interface roughness depends on the virging silicon surface morphology and its chemical state, on bulk properties, and on the parameters of oxidation. The influence of the interfacial structure in MOS inversion layers on electronic properties like mobility, interface states, fixed oxide charges, and on the dielectric breakdon behaviour will be demonstrated.