Strain and substoichiometry at the Si(100)/SiO2 interface -: art. no. 245305

Interfacial strain and substoichiometric silicon oxides are the two principal causes that result in the redshift of the transverse and longitudinal optical phonons of the asymmetric stretch of O in the Si-O-Si bridging bond of thermal SiO2 with decreasing oxide thickness. Analyses to comprehend these effects, therefore, require a consideration of both strain and interfacial substoichiometry. A method to isolate the contributions of strain and substoichiometry towards the observed shifts is proposed. The procedure, which utilizes a simple optical model and an effective medium approximation, allows an estimation of the average strain and substiochiometry in films of different thicknesses. Analyses of oxides formed at two different temperatures (550 and 700 degreesC) with dry and wet oxygen reveal how process conditions affect the interface properties.