Distinguishability of N composition profiles in SiON films on Si by angle-resolved X-ray photoelectron spectroscopy

Abstract

We report on the use of the NIST Database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to determine N 1s, O 1s, and Si 2p 3/2 photoelectron intensities for a 25 Å SiON film on a Si substrate with different distributions of N in the film. These simulations were made to assess the distinguishability of angle-resolved x-ray photoelectron spectroscopy (ARXPS) signals for each N distribution. Our approach differs from conventional simulations of ARXPS data in that we do not neglect elastic scattering of the photoelectrons and the finite solid angle of the analyzer. Appreciable dispersion of the photoelectron intensities was found only for the N 1s intensities at an emission angle of 75° (with respect to the surface normal). Conventional analyses of ARXPS data that include such large emission angles are unlikely to be valid due to angle-dependent changes of the attenuation length. We demonstrate the magnitude of elastic-scattering and analyzer solid-angle effects on the calculated angular distributions. © 2007 American Institute of Physics.