Ellipsometric analysis of ultrathin oxide layers on SIMOX wafers

Ellipsometric analysis of surface SiO2 on Separation by IMplanted OXygen SIMOX.wafers has been performed. Spectroscopic ellipsometry data in the range of 500–850 nm were fitted based on a structure model composed of surface SiO2, surface Si, and buried SiO2layers as well as transition layers at the SiO2rSi interfaces. From the fitting results, it is found that there exist transition layers with a thickness of 1.6 and 2.0 A° at the surface SiO2rsurface Si and buried SiO2rSi interfaces, respectively. Angle-resolved He–Ne laser ellipsometry has been also applied for in-situ monitoring of oxidation processes of SIMOX wafers and it is shown that ultrathin oxide thickness can be determined with an accuracy of 3 A° . q2000 Elsevier Science B.V. All rights reserved