SILICON-INSULATOR INTERFACE PROBING BY REFLECTED OPTICAL SECOND-HARMONIC GENERATION

Optical second harmonic generation (SHG) has been applied to the study of the silicon-insulator (S-I) interface. Results from real-time measurements of the SHG intensity during etching process of SiO2 and Si3N4 insulator layers are presented and analysed taking into consideration various contributions to the nonlinear polarization in the S-I interface such as the silicon substrate, the static electric field, the inhomogeneous deformation and the crystalline oxide interlayer. The symmetry properties of the silicon-insulator interface have also been determined by an analysis of the SHG rotational dependences.