Nitrogen out-diffusion from Czochralski silicon monitored by depth profiles of shallow thermal donors

A new technique to measure nitrogen out-diffusion profiles C(z) in oxygen-containing samples was developed and applied to study out-diffusion at 950 to 1050degreesC. Shallow Thermal Donors (nitrogen-oxygen complexes) are subsequently generated at 650degreesC. A measured depth profile of these donors provides 'an imprint' of nitrogen profile, by which the C(z) curve can be restored. In the presence of oxygen, the diffusion problem is simplified by a fast oxygen-assisted dissociation of dimers; but somewhat complicated by formation of nitrogen-oxygen complexes. It is however concluded that the nitrogen species are not strongly oxidized, and dimers are the dominant nitrogen species, as in float-zoned material. The values obtained for the dissociation diffusion parameter D1K1/2 (where D, is the monomeric diffusivity and K is the dissociation constant) are in a qualitative agreement with those found earlier.