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

Yield (counts per 5 µC)
450
400
350
300
250
200
150
100
50
4500
400
350
300
250
200
150
100
50
60 nm SOI, PAI, 3keV As 1E15 ion/cm 2 [111] Blocking direction
25 20 15 10 5 0
O depth
6 4 2 0
Si depth (nm)
a) 550 C
virgin
Random
as-impl
200s
500s
600s
As depth (nm)
14 12 10 8 6 4 2 0
c) 650 C
0
66 68 70 72 74 76 78 80 82 84 86 88 90 92 94
Results from the samples annealed at 600 °C are shown in Figure 6.25b. The
anneal times used, appear to have captured stages in the regrowth process that follow on
from the sample annealed at 550 °C for 600s. The sample annealed for 60 s shows a
profile that could be thought to consist of different damage regions. There is an ~ 7 nm
wide fully amorphous layer beyond which there is region, at depth from 7 to 16 nm,
with a high level of residual damage, as evidenced by a scattering yield substantially
above the dechannelling level of around 75 counts. For the sample annealed for 70 s the
amorphous layer has reduced to ~ 5 nm and is accompanied by a considerable, but not
complete, regrowth of the residual damage region seen with the 60 s anneal. Annealing
for 90 s produces a further reduction in the width of the surface peak and a substantial
reduction in the residual damage. Annealing for 200 s produces an almost completely
regrown layer. Here the additional width of the Si peak relative to the virgin spectra is
to some extent accounted for by the increased oxide layer thickness. However the height
of the Si peak is greater than that of the virgin sample suggesting that the layer is still
not quite fully regrown. For this series of samples a general sharpening-up of the a/c
160
O depth
6 4 2 0
Si depth (nm)
25 20 15 10 5 0
25 20 15 10 5 0
Si depth (nm)
virgin
Random
as-impl
Si depth (nm)
O depth
6 4 2 0
8s
10s
11s
12s
15s
30s
O depth
6 4 2 0
b) 600 C
virgin
Random
as-impl
60s
70s
90s
200s
d) Higher Temp
virgin
Random
as-impl
700C 15s
1050C sp
66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96
Energy (keV)
25 20 15 10 5 0
As depth (nm)
14 12 10 8 6 4 2 0
As depth (nm) As depth (nm)
14 12 10 8 6 4 2 0
14 12 10 8 6 4 2 0
Figure 6.25 MEIS energy spectra from 60 nm SOI samples, pre amorphised with 40 keV Xe
1E14 cm -2 and implanted with 3 keV As to 1E15 cm -2 , annealed at a) 550 °C, b) 600 °C, c)
650 °C, and d) higher temperatures.