THE EFFECT OF OXYGEN ON THE FORMATION OF IRON SILICIDE

By evaporating Fe onto Si(100) substrates in an oxygen ambient, oxygen concentrations of 2, 3, 10 and 35 at% could be gettered in four Fe fi lms. Auger electron spectroscopy (AES) and X-ray photoelectron spectro scopy (XPS) were used to investigate the redistribution of the oxygen after the samples were annealed at 823 K for 9, 49, 81 and 121 min. Fo r a low concentration (2 at%) of oxygen, it was found that the oxygen in the Fe film accumulated at the Fe/silicide interface during silicid e formation. Si is the main diffusion species during silicide formatio n for pure Fe on Si. If oxygen was present in the Fe layer it was foun d that Fe is the main diffusion species during silicide formation. The formation of SiO(x), 1 less-than-or-equal-to x less-than-or-equal-to 2, in the accumulated oxygen layer acted as a diffusion barrier. The p resence of higher concentrations of oxygen in the Fe layer prevented a ny silicide formation due to FeO formation.