Oxidation kinetics of Mg-, Si-, and Fe-implanted aluminum by using X-ray photoelectron spectroscopy

The oxidation kinetics of Mg-, Si-, and Fe-implanted aluminum has been stud ied at room temperature and a water vapor pressure of 2.0 x 10(-6) Pa using X-ray photoelectron spectroscopy. The elements Mg, Si, and Fe were implant ed into high-purity aluminum at low ion doses from 6.0 x 10(12) to 3.6 x 10 (13) ions.cm(-2). Secondary ion mass spectrometry (SIMS) depth profiles hav e shown that the element distributions of Mg and Fe in aluminum are consist ent with the theoretical depth profiles calculated using a TRIM (transport of ions in matter) program. The implanted elements are distributed in the n ear-surface region with their maximum concentration at the depth of similar to 50 nm. In the case of implanted Si, however, SIMS depth profile shows n o maximum concentration peak and the near-surface concentration is much hig her than that calculated. This is ascribed to diffusion of Si toward the su rface during implantation. Oxidation kinetics of implanted aluminum have sh own that surface concentrations of implanted Si, as low as 40 ppm, cause an increase in the Al oxidation rate compared to the pure metal. By contrast, implanted Mg, surface concentration from 20 to 120 ppm, results in a lower ed oxidation rate until the oxide reaches a thickness of similar to 0.55 nm , and after that a rapid increase in oxidation occurs. Implanted Fe does no t cause any change in the oxidation rate of aluminum. These oxidation kinet ics can be explained on the basis of metal vacancies in the defect structur e of aluminum thin oxide films. The effects of surface damage caused by the ion beam during the implantation experiment were also determined by measur ements of oxidation kinetics.