It was shown that the temperature and the applied cooling rate during a Pt diffusion process strongly influenced the electrical conductivity in weakly P doped Si. Diffusion was performed at 800 to 950C for several hours. Spreading resistance profile analyses clearly showed an n-type to p-type conversion under the surface when samples were slowly cooled (5C/min). Only a compensation of the P donors was observed when samples were quenched. This mechanism was reversible. Five Pt-related deep levels, including the acceptor level at 0.23eV from the conduction band, were observed. One of them was located at 0.427eV from the valence band and could be related to the acceptor state at the origin of the type conversion mechanism. This acceptor state could be associated with a complex defect based on the association of a substitutional Pt atom with interstitial atoms (Pt, O) or intrinsic point defects.

Influence of the Applied Cooling Rate on the Type Conversion of Platinum Diffused N-Type Silicon. L.Ventura, B.Pichaud, F.Lanois, A.Lhorte: Japanese Journal of Applied Physics - 1, 2001, 40[6A], 3938-43