Retarded diffusion of boron in Si due to the formation of an epitaxial CoSi2 layer

The diffusion of boron in silicon with and without a 20-nm thick epitaxial CoSi2 layer was investigated by secondary ion mass spectrometry (SIMS) usin g doping superlattices (DSLs). For specimens without CoSi2 layer, we observ ed oxidation enhanced diffusion (OED) of B in Si in accordance with the lit erature. However, B diffusion in silicide capped specimens was found to be retarded by about a factor of 20 as compared to specimens without a silicid e layer. The measured diffusivity was even less than the intrinsic thermal diffusivity of B in Si. (C) 1998 Elsevier Science S.A. All rights reserved.