COMPARATIVE-STUDY OF SIMOX STRUCTURES USING 4 ANALYTICAL TECHNIQUES

Pour analytical techniques have been employed to characterize 'Separat ion by Implanted Oxygen' (SIIMOX) structures of both poor and good qua lity with the aim of determining the application limits of the techniq ues used. Rutherford backscattering spectrometry in conjunction with c hannelling (RBS/C) of 1.5 MeV He+ ions and cross-sectional transmissio n electron microscopy (XTEM) have been utilized to evaluate the sample s. The two optical techniques that have been used are polarized infrar ed reflection (PIRR) in the range of 800-7000 cm(-1) and variable-angl e 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 mult ilayer model is reported. The optical multilayer models as well as the correction of PIRR data are discussed in detail. Good agreement of th e layer thicknesses evaluated by the optical techniques and RES has be en found. While silicon islands within the buried oxide can only be qu alitatively detected by RES, VASE can provide more detailed informatio n on the SIMOX structures. Cross-sectional TEM is a complementary tech nique to RES and VASE/PIRR as it yields detailed information on the de fects, shape and distribution of silicon islands as well as on the int erfacial roughness. At the same time, layer thickness measurements usi ng XTEM have been found to be less reliable in some cases.