Density Functional Theory Study on Anisotropic Arrangement of Interstitial Oxygen Atoms at (001) Interface of Oxide Precipitates in Si Crystal

Abstract

The stability of the anisotropic oxygen (O) arrangement at the (001) interface of oxide precipitate (OP) in a Si crystal was analyzed by the density functional theory to understand the OP/Si interfacial structure and the gettering mechanism at the interface at an atomic level. In contrast to the case of the Si bulk, the O atoms align in one Si–Si zig-zag bond to some extent, then start to occupy other Si–Si bonds. After the O atoms are arranged in multiple series in the first interface layer to some extent, those in the second layer become more stable. This trend was confirmed for the second and third layers. The results support the existence of an experimentally observed transition layer with a composition of SiO x (x < 2) at the interface [Kissinger et al., ECS J. Solid State Sci. Technol., 9, 064002 (2020)]. Furthermore, several O alignments at the interface drastically reduce the formation energy of Si vacancies. The vacancies at the OP/Si interface were found to be effective gettering sites for Cu while the dangling bond was found to be an effective gettering site for Ni with a binding energy exceeding 1 eV.