The diffusion and activation of low-energy implanted B in F pre-amorphized material was studied during rapid thermal annealing. When compared with low-energy B or BF2 implantation into crystalline Si, low-energy B ion implantation into F pre-amorphized Si permitted the formation of shallow junctions with a reduced junction depth and an increased B activation. The use of F pre-amorphization suppressed transient enhanced diffusion in the low B concentration region and resulted in a steep dopant profile which was necessary for shallow junction formation. Secondary ion mass spectroscopy and cross-sectional transmission electron micrography revealed the occurrence of F accumulation near to the surface, and at end-of-range defects. The interaction of F with defects was believed to reduce B diffusion in the low B concentration region. Low-energy B implantation into F pre-amorphized material, followed by rapid thermal annealing, was concluded to be a promising process for shallow junction formation.

Influence of Fluorine Preamorphization on the Diffusion and Activation of Low-Energy Implanted Boron during Rapid Thermal Annealing. T.H.Huang, H.Kinoshita, D.L.Kwong: Applied Physics Letters, 1994, 65[14], 1829-31