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

(FWHM). Concomitantly, As in the regrown region has taken up substitutional
positions invisible to the analysing beam. A small amount of As segregation has
occurred, as evidenced by the slight As yield increase at a depth around 5 nm. These
findings are entirely similar to those described in section 6.3. No major differences
between the different materials are observed. With these shallow implants the implant is
well away from the BOX. In this instance the SOI materials would be expected to
behave as bulk material, as observed.
Yield (counts per 5 µC)
450
400
350
300
250
200
150
100
50
0
O depth (nm)
6 4 2 0
3keV As 2E15 ion/cm 2 [111] Blocking direction
Si depth (nm)
16 14 12 10 8 6 4 2 0
70 72 74 76 78 80 82 84 86 88 90 92 94 96
Energy (keV)
6.4.3.2 60nm SOI PAI (40 keV Xe) 3 keV As 1E15
A 60 nm SOI wafer was pre-amorphised with 40 keV Xe + (PAI) to a dose of
1E14 ions/cm 2 . XTEM results (not shown) reveal that the PAI produces an amorphous
layer to a depth of approximately 35 nm (13). The PAI was followed by a 3 keV As
implant to a dose of 1E15 ion/cm 2 . Note that the As dose was half that of the As
implants previously used in this project, (in section 6.2 and 6.3). This would not be
expected to fundamentally affect the regrowth mechanism, but probably the regrowth
158
virgin
Random
Bulk as-impl
Bulk 600C 30s
60nm SOI as-impl
60nm SOI 600C 30s
100nm SOI as-impl
100nm SOI 600C 30s
As depth (nm)
16 14 12 10 8 6 4 2 0
Figure 6.24 MEIS energy spectra from bulk Si, 60 nm SOI and 100 nm SOI samples,
implanted with 3 keV As to a dose of 2E15 ions/cm 2 , as-implanted and following annealing
at 600 °C for 30s.