The diffusion of antimony in heavily doped and n- and p-type silicon

Abstract

The diffusion of Sb in heavily doped n- and p-type Si has been studied to determine the activation energies and charge states of the point defects responsible for Sb diffusion. It is shown that neutral point defects, probably V^x, dominate under intrinsic doping conditions. For samples doped with high-concentration As or P backgrounds, Sb diffusion is dominated by a double-negatively charge point defect that causes an n² concentration-dependent Sb diffusivity. Electric-field effects also are important. The measured diffusion coefficients are D_i^x = 17.5 exp(−4.05 eV/kT), and D_i⁼ = 0.01 exp(−3.75 eV/kT). The activation energies are consistent with diffusion via V^x and V⁼ vacancies. Retarded diffusion of Sb in p⁺-doped samples with uniform B profiles fits an ion pairing model where Sb⁺B⁻ pairs form to reduce the flux of Sb atoms.