Influence of fluorine preamorphization on the diffusion and activation of low-energy implanted boron during rapid thermal annealing

Abstract

The diffusion and activation of low‐energy implanted B in F preamorphized Si during rapid thermal annealing has been studied. Compared with low‐energy B or BF₂ implant into crystalline Si, low‐energy B ion implantation into F preamorphized Si allows the formation of shallow junctions with reduced junction depth and increased B activation. F preamorphization suppresses the B transient enhanced diffusion in the low B concentration region resulting in a steep dopant profile which is necessary for shallow junction formation. Secondary ion mass spectroscopy and cross‐sectional transmission electron micrograph results show F accumulation near the surface and at end‐of‐range defects. The interaction of F with defects is believed to reduce B diffusion in the low B concentration region. Low‐energy B implant into F preamorphized Si followed by rapid thermal annealing has been demonstrated as a promising process for shallow junction formation.