Defect Generation Mechanism of Epitaxially Grown In Situ Phosphorus-Doped Silicon on Silicon (111) Substrate

There are many studies regarding improving the quality of in situ phosphorus-doped (ISPD) epitaxial silicon films as a source and drain material to achieve low specific contact resistivity. The top surfaces of these films, contact interface, in 3D structure devices such as Fin field-effect transistor and gate-all-around field-effect transistor are grown from diamond-shaped source and drain with four edges of the (111) surfaces. Therefore, the physical properties of these sources and drains in a 3D structure device are strongly related to those of ISPD silicon grown on the (111) substrate. Here, ISPD silicon is grown using reduced pressure chemical vapor deposition on a silicon (111) substrate at 700 °C, and this film is analyzed using high-resolution transmission electron microscopy, atom probe tomography, and energy-dispersive X-ray spectroscopy (EDX). The results show that this film exhibits many defects such as twin or stacking fault, and phosphorus exhibits cluster distribution. To confirm the relationship between phosphorus and defect generation, an atomic resolution EDX mapping of phosphorus atoms is used, and the position of the observed defects corresponds with the clustered phosphorus in a mapping image.