Understanding and Control of Stress at Si-SiO<sub>2</sub> Interface

Abstract

This paper presents the results of the investigation of stress relaxation at the Si-SiO2 interface using electron paramagnetic resonance (EPR) spectra, scanning electron microscopy (SEM) image technique, deflection analysis, X-ray photoelectron spectroscopy (XPS) and C-V characterisation of metal oxide semiconductor (MOS) structures. It has been shown, on the basis of EPR, XPS, C-V, and deflection data, that the mechanism of stress relaxation depends on the oxidation conditions: temperature, cooling rate and oxide thickness. In the Si-SiO2-Si3N4 system the stress relaxation occurs due to the difference in the thermal expansion coefficient of SiO2 and Si3N4 material. With an appropriate choice of oxidation conditions compressive stresses in SiO2 and tensile stresses in Si are almost equal and stress can be reduced considerably at the interface.