Eur. Phys. J. AP 23, 33-37 (2003)
https://doi.org/10.1051/epjap:2002114

p-type doping by platinum diffusion in low phosphorus doped silicon

¹ LMP, EA 3246, 16 rue Pierre et Marie Curie, BP 7155, 37071 Tours Cedex 2, France
² TECSEN, UMR 6122 CNRS, Université Aix-Marseille III, 13397 Marseille Cedex 20, France
³ STMicroelectronics, 16 rue Pierre et Marie Curie, BP 7155, 37071 Tours Cedex 2, France

Corresponding authors: laurent.ventura@st.com ventura@univ-tours.fr

Received: 23 May 2002
Revised: 12 September 2002
Accepted: 19 September 2002
Published online: 29 November 2002

Abstract

In this work we show that the cooling rate following a platinum diffusion strongly influences the electrical conductivity in weakly phosphorus doped silicon. Diffusions were performed at the temperature of 910 °C in the range of 8–32 hours in 0.6, 30, and 60 Ω cm phosphorus doped silicon samples. Spreading resistance profile analyses clearly show an n-type to p-type conversion under the surface when samples are cooled slowly. On the other hand, a compensation of the phosphorus donors can only be observed when samples are quenched. One Pt related acceptor deep level at 0.43 eV from the valence band is assumed to be at the origin of the type conversion mechanism. Its concentration increases by lowering the applied cooling rate. A complex formation with fast species such as interstitial Pt atoms or intrinsic point defects is expected. In 0.6 Ω cm phosphorus doped silicon, no acceptor deep level in the lower band gap is detected by DLTS measurement. This removes the opportunity of a pairing between phosphorus and platinum and suggests the possibility of a Fermi level controlled complex formation.