Dynamic segregation of metallic impurities at SiO2/Si interfaces
Abstract
The behaviour of two metallic impurities, iron and tungsten, during oxidation of silicon wafers has been investigated using transmission electron microscopy and atom probe tomography. Metallic contamination has been introduced by implantation of 54Fe at 65 keV and 186W at 150 keV, with a dose of 1015 at/cm2. Oxidation of Fe-contaminated Si wafer results in the precipitation of iron as β-FeSi2 at the SiO2/Si interface. The presence of these precipitates hinders the oxidation front which forms silicon pyramidal defects. Further oxidation of the precipitates leads to iron-rich cluster formation in the SiO2 layer, surrounding the pyramids. Dry oxidation of a tungsten-contaminated Si wafer is characterised by the formation of nanometric spherical precipitates in the Si layer. The size and density of these precipitates versus depth follow the as-implanted W concentration profile.
- Publication:
-
Journal of Physics Conference Series
- Pub Date:
- November 2013
- DOI:
- 10.1088/1742-6596/471/1/012029
- Bibcode:
- 2013JPhCS.471a2029D