The effect of surface oxidation upon Sb diffusion was investigated. An extrinsic As background was used to provide a constant electron concentration for the diffusion of the Sb profile. Annealing was carried out at 850, 950 or 1050C, and the diffusion of Sb and As was measured under inert and oxidizing conditions by means of secondary ion mass spectrometry. It was found that the diffusion of As was enhanced, while the diffusion of Sb within the As layer was retarded. The data could be described by:

DSb = 0.214 exp[-3.65/kT] + 15 (n/ni)exp[-4.08/kT]

and

DAs = 8.0 exp[-4.05/kT] + 12.8 (n/ni)exp[-4.05/kT]

where n/ni accounted for the concentration dependent diffusion which was proportional to the donor concentration (n) over the intrinsic electron concentration (ni). It was concluded that the results provided support for a dual, interstitial/vacancy, mode of dopant diffusion. They also provided evidence against the use of a vacancy-only diffusion model.

Retarded Diffusion of Sb in a High Concentration As Background during Silicon Oxidation. E.A.Perozziello, P.B.Griffin, J.D.Plummer: Applied Physics Letters, 1992, 61[3], 303-5

Table 99

Diffusivity of Sb in Si