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ARXPS analysis of silicon oxide films

C. C. NEGRILA1, C. COTIRLAN1, F. UNGUREANU1, C. LOGOFATU1, R. V. GHITA1,* , M. F. LAZARESCU1

Affiliation

  1. National Institute of Materials Physics, P.O.Box MG-7, Magurele, Bucharest, Romania

Abstract

Angle-resolved X-ray Photoelectron Spectroscopy (ARXPS) has been performed on (100) Si surfaces in different conditions as regards the oxides nature - native oxides, thermally formed oxides, and also after a cleaning procedure by Ar+ ion sputtering (e.g. E= 2 keV). The most sensitive angle to surface oxidation states (Si1+, Si2+, Si3+, Si4+) was the take-off-angle (TOA): 25o. Native oxides and thermally oxide phases on Si surfaces consists in a mixture of Si2O, SiO, Si2O3 and SiO2. The XPS measurements have putted into evidence a higher concentration of suboxides in high oxidation state (Si3+) on naturally oxidized Si substrates. The thermally oxidized Silicon surfaces contain suboxides in a low oxidation state (Si1+). The Ar+ ion sputtering removed rapidly the superficial silicon oxides. The analysis and computation of SiO2 film thickness on crystalline Silicon was done in the frame of modified Bethe equation for Electron inelastic mean free path (IMFP) and taking into account the intensity of SiO2 peak and Si peak together with the TOA in the XPS measurement. Native oxide thickness for SiO2 was doxy ~ 24Å and for thermally oxidized sample was doxy~ 27Å. Due to the slightly difference in the nature oxidation states it is suggested that the silicon dioxide appeared from two different kinetics in the oxidation processes..

Keywords

ARXPS technique, Native oxides, Thermal oxides, Inelastic mean free path (IMFP), Silicon dioxide film thickness.

Submitted at: May 22, 2008
Accepted at: June 9, 2008

Citation

C. C. NEGRILA, C. COTIRLAN, F. UNGUREANU, C. LOGOFATU, R. V. GHITA, M. F. LAZARESCU, ARXPS analysis of silicon oxide films, Journal of Optoelectronics and Advanced Materials Vol. 10, Iss. 6, pp. 1379-1383 (2008)