Damage formation and annealing studies of low energy ion implants ...

existence of Xe agglomerates at depth between 10 and 15 nm, in agreement with the
MEIS peak observed at ~13 nm for the 3 keV BF2 implant. The size of these
agglomerates was seen to grow with increasing anneal temperature, in a ripening
process. It is likely that the agglomerated Xe is in bubbles.
a) Xe M-edge, ~ 670 eV energy loss electrons
b) Xe N-edge, ~ 65 eV energy loss electrons
Figure 7.9 EFTEM images of a Xe PAI, 3keV BF2 implanted Si
sample after annealing to 1025 °C for 10 s using electrons with an
energy loss corresponding to (a) the M ionisation edge and (b) from
the N ionisation edge of Xe.
Summarising the above observations and considering the results from literature
it appears that during SPER most F migrates, probably in front of the moving a/c
interface to the surface where it is trapped. The rest of the implanted F, approximately
10 %, moves in deeper, to a depth surrounding the EOR of the BF2 + implant. Xe equally
moves to the surface and ~ 50 % is trapped at a depth that coincides with the depth of
the deeper F peak. The remainder of the Xe is assumed to diffuse out. During SPER a
small amount of B is trapped at the same depth.
The precise details of the interaction, i.e. the exact sequence of events, are not
known, nor the reasons for the interaction. Trapping of some F at a depth of the EOR of
the BF2 has been observed before (4), but in these cases the samples were not preamorphised
and so there would be a clear defect structure in the damaged crystalline Si
to act as a gettering site. In this set of experiments, the end of range of the BF2, was
located in amorphous Si. It is known that defect structures can exist within an
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