Comparative Study of SIMOX Structures Using Four Analytical Techniques

Abstract

Four analytical techniques have been employed to characterize ‘Separation by Implanted Oxygen’ (SIMOX) structures of both poor and good quality with the aim of determining the application limits of the techniques used. Rutherford backscattering spectrometry in conjunction with channelling (RBS/C) of 1.5 MeV He+ ions and cross-sectional transmission electron microscopy (XTEM) have been utilized to evaluate the samples. The two optical techniques that have been used are polarized infrared reflection (PIRR) in the range of 800–7000 cm-1 and variable-angle spectroscopic ellipsometry (VASE) over the wavelength range 250–1700 nm. The combination of these two optical techniques by simultaneously evaluating all the experimental data on the basis of one optical multilayer model is reported. The optical multilayer models as well as the correction of PIRR data are discussed in detail. Good agreement of the layer thicknesses evaluated by the optical techniques and RBS has been found. While silicon islands within the buried oxide can only be qualitatively detected by RBS, VASE can provide more detailed information on the SIMOX structures. Cross-sectional TEM is a complementary technique to RBS and VASE/PIRR as it yields detailed information on the defects, shape and distribution of silicon islands as well as on the interfacial roughness. At the same time, layer thickness measurements using XTEM have been found to be less reliable in some cases.