Contribution of Carbon to Growth of Boron-Containing Cluster in Heavily Boron-Doped Silicon

Abstract

It is well known that substitutional carbon (C) atoms can capture excess self-interstitial silicon (Si) atoms and suppress the diffusion of ion-implanted interstitial-type dopants, such as boron (B), in Si. In the case of B concentrations as high as ∼1×1021 cm-3, the B activation ratio in Si decreases with C incorporation. Thus, many studies on stable B-containing clusters and/or precipitates in heavily doped Si with a C additive have thus far been conducted. However, the impact of the C incorporation on the activation and clustering of B atoms in Si is yet to be researched. In this work, the chemical bonding features of B and C atoms in heavily B-doped Si with different C contents after high-temperature annealing were characterized systematically by high-resolution X-ray photoelectron spectroscopy (XPS). It was found that the C incorporation enhances B-clustering at B concentrations higher than ∼1×1021 cm-3 after 1050 °C spike annealing. In addition, the formation of C–B bonds with accompanying B-clustering was confirmed by photoemission measurement using a hard X-ray. As a result, the intrinsic B-diffusion was observed to be markedly suppressed by the C incorporation under thermodynamic equilibrium annealing at 1000 °C.