Comparative investigation of the Si/SiO_2 interface layer containing SiC crystallites using spectroscopic ellipsometry, ion beam analysis and XPS

摘要

It is known from earlier publications that SiC crystallites grow at the interface of a Si/SiO_2 system during heat treatment in CO containing ambient. First 100 nm thick SiO_2 layers were thermally grown on <100> Si substrates. The Si/SiO_2 structures were heat treated in CO containing atmosphere for 20 and 102 hours at 1190 ℃ for investigation. Spectroellipsometry was applied to study the microstructure of the heat-treated samples. We assumed a layer at the Si/SiO_2 interface that contains crystalline Si and crystalline rnSiC. After 20 and 102 hour annealing the layer thickness extracted from evaluation of ellipsometric data was 15 nm and 25 nm, the volume fraction of SiC was 38% and 89%, respectively. To confirm the results of the ellipsometry characterization we applied ion beam analysis and X-ray photoelectron spectroscopy. For determination of the carbon content a ~4He~+ ion beam of 3.5 MeV was selected to take advantage of the scattering cross section of carbon at 165° detection angle is about six times larger than the Rutherford type one.