Grazing Incidence X-ray Photoelectron Spectroscopy (GIXPS) is a method that offers promise as a non-destructive technique to measure the thickness and chemistry of ultrathin gate dielectric films. It combines aspects of x-ray reflectivity and conventional x-ray photoelectron spectroscopy (XPS). Collimated x-rays are incident on the sample at a grazing angle. A series of photoemission spectra are obtained over a range of incidence angles in the vicinity of the critical angle for total external reflection. The advantage of this method is the incorporation of the optical constants of the layers, as well as the photoemission cross sections of the elements and the inelastic attenuation lengths of the escaping photoelectrons, to fit the nonlinear variation of the photoemission spectra as a function of angle. The x-ray field variation with angle within individual layers provides additional constraints beyond standard angle-resolved XPS for interpreting the densities and thicknesses of multiple layers. The application of this method to the analysis of oxide on Si is described.
Citation: Surface and Interface Analysis
Pub Type: Journals
CMOS, gate dielectric, GIXPS, grazing incidence, silicon, total external reflection, total reflection, TRXPS, XPS