Uncertainties caused from surface contaminations to estimate the thickness of SiO/sub 2/ ultrathin films

The development of the evaluation method for the thickness of ultrathin SiO/sub 2/ films on a Si substrate is a very important. SiO/sub 2/ is currently used as a gate dielectric material of a metal-oxide-semiconductor field effect transistors (MOSFET), and thicknesses of the film have been decreasing every year. In ITRS (International Technology Road Map for Semiconductors), it is required to measure the film thicknesses in the range of 1.8-0.6 nm with an uncertainty (3/spl sigma/) of /spl plusmn/ 4% in near feature. It is necessary for the accurate evaluation of a film thickness to estimate the various factors of the uncertainty. In this study, we focus on an effect of surface contaminations as one of the component of the uncertainties for thickness estimations. We propose an estimation method of the SiO/sub 2/ film thickness without surface contamination effect by using grazing incidence X-ray reflectivity (GIXRR) and X-ray photoelectron spectroscopy.