Shallow p+n junctions have been formed through a combination of
pre-amorphization of the silicon surface by implantation of 28Si,
33Ar, or 73Ge, low energy implantation of boron or
BF2+, and rapid thermal annealing (RTA) in a tunqsten halogen lamp
system. Both pre-amorphization and RTA are required to form a shallow
(<0.25 μm) junction, for either boron or BF2+. Arqon pre-amorphization results in poor electrical activation
of the boron, while germanium gives the lowest sheet resistivity, but is
responsible for a deep boron tail during implantation. The residual damage
is characterized by a plane of dislocation loops centred either close to the
boron concentration peak, for B+ implantation into a crystalline
substrate, or at the original amorphous-crystalline interface, for
pre-amorphized specimens.