The diffusion of Zr into ultra-thin thermally grown SiO2 on Si(100), from Zr-rich oxides at 750 to 1000C in a N2 ambient, was studied by using a combination of photo-emission measurements and wet-chemical SiO2-thinning in a dilute HF solution. The chemical bonding features incorporated Zr atoms into SiO2 and the influence of the Zr incorporation upon the gap states were also evaluated by analyzing X-ray photo-electron and total photo-electron yield spectra, respectively. The measured Zr depth profiles show that the Zr diffusion at 750 and 900C could be characterized as the cases under constant-surface-concentration conditions with the diffusion constants of about 10-19cm2/s at 750C and about 10-18cm2/s at 900C, while the diffusion at 1000C was likely to be the case under a constant-total-concentration condition. No increase in the gap states with Zr incorporation into SiO2 was confirmed by total photoelectron yield measurements.

Diffusion and Incorporation of Zr into Thermally Grown SiO2 on Si(100). M.Yamaoka, H.Murakami, S.Miyazaki: Applied Surface Science, 2003, 216[1-4], 223-7