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

annealed samples are shown in Figure 6.19. A random spectrum, from an amorphous
sample and a spectrum from a virgin Si sample are included in the figure for reference.
Approximate depth scales, for scattering off As, Si and O atoms have been added to the
figure.
Yield (counts per 5 uC)
450
400
350
300
250
200
150
100
50
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
0
68 70 72 74 76 78 80 82 84 86 88 90 92 94 96
Energy (keV)
The spectra of both the Cz and Epi as-implanted samples show that there are no
observable differences using MEIS between the Cz or Epi implanted silicon wafers.
None are expected in view of the rapid amorphisation rates in Si for As ions. The
arsenic peaks coincide and the depths of the back edges of the amorphous layer to are
within 0.2 nm.
Although the temperatures and times do not follow a systematic isothermal or
isochronal series, the different anneals have captured various stages of regrowth along
the way to fully regrown crystalline Si. The 550 °C 200 s annealed Si sample has
regrown to a depth of ~ 7 nm, and the 600 °C 20 s anneal to a depth of ~ 6 nm. For the
samples annealed at 650 °C 10 s and 700 °C 10 s the regrowth process is almost
complete. Any minor differences with the previous set of samples (section 6.3.2.2) can
be ascribed to small differences between the anneals.
151
As depth (nm)
virgin
Random
Cz as-implanted
Cz 550C 200s
Cz 600C 20s
Cz 650C 10s
Cz 700C 10s
Epi as-implanted
Epi 550C 200s
Epi 600C 20s
Epi 650C 10s
Epi 700C 10s
14 12 10 8 6 4 2 0
Figure 6.19 MEIS energy spectra for the Epi and Cz Si samples, implanted with 3 keV As, asimplanted
and following various anneals.