Ellipsometric analysis of ultrathin oxide layers on SIMOX wafers

Ellipsometric analysis of surface SiO2 on Separation by IMplanted OXygen (S IMOX) wafers has been performed. Spectroscopic ellipsometry data in the ran ge of 500-850 nm were fitted based on a structure model composed of surface SiO2, surface Si, and buried SiO2 layers as well as transition layers at t he SiO2/Si interfaces. From the fitting results, it is found that there exi st transition layers with a thickness of 1.6 and 2.0 Angstrom at the surfac e SiO2/surface Si and buried SiO2/Si interfaces, respectively. Angle-resolv ed 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 t hickness can be determined with an accuracy of 3 Angstrom. (C) 2000 Elsevie r Science B.V. All rights reserved.