Apparent effective attenuation length of photoelectron in SiO observed by synchrotron radiation photoemission spectroscopy

Jinno, Muneaki*; Inoue, Keisuke*; Teraoka, Yuden

The thickness of ultra thin film on a substrate can be measured by synchrotron radiation (SR) XPS. Effective attenuation length (EAL) corresponding to the SR energy is necessary to calculate the film thickness. The SR energy dependence of EAL was obtained for SiO films. The SR energy range was from 400 eV to 1700 eV. SiO thin films, produced by a rapid thermal oxidation method on the Si(001) substrate, were prepared. The maximum thickness was measured as 3.57 nm by ellipsometry. Si2p photoemission spectra were measured and deconvoluted. Si suboxides were included into calculations as three patterns in this study; (1) included into an silicon dioxide, (2) neglected, (3) included into an silicon bulk. Si suboxides are overestimated in high energy side. This is due to contribution of defects and impurities in the bulk overlapping on the chemical shifts of Si suboixides.