Damage formation and annealing studies of low energy ion implants ...
Damage formation and annealing studies of low energy ion implants ... Damage formation and annealing studies of low energy ion implants ...
identical to the 60 nm SOI series in Figure 6.26b) using 3 keV BF2 and hence the same observations apply. Summarising this section, the unusual regrowth of SOI wafers seen with the PAI As implanted samples is also seen with the PAI BF2 implanted samples. The most significant feature is the wide a/c interface of up to 14 nm width. Upon continued annealing this proceeds towards the surface, where there is a tightening of the a/c interface. The regrowth on the PAI SOI samples appears to be delayed relative to the rate of regrowth in bulk Si. Yield (counts per 5 µC) 400 350 300 250 200 150 100 50 a) Bulk, PAI, 3keV BF 2 20 15 10 5 0 20 15 10 5 0 20 15 10 5 0 Si depth (nm) Si depth (nm) Si depth (nm) virgin random 550C 600s 600C 60s 650C 15s 700C 15s 0 68 70 72 74 76 78 80 82 84 b) 60nm SOI, PAI, 3keV BF 2 68 70 72 74 76 78 80 82 84 68 70 72 74 76 78 80 82 84 Energy (keV) 6.4.3.4 88 nm SOI vs. bulk Si, PAI Xe 40 keV 1E14, As 3 keV 2E15 In order to confirm the differences in regrowth behaviour for bulk Si and SOI, a series of experiments was performed using identical implantations and simultaneous anneals on bulk Si and 88 nm SOI. Both wafers were pre-amorphised with 40 keV Xe to a dose of 1E14 cm -2 and implanted with 3 keV As to a fluence of 2E15 cm -2 , conditions typically used in this thesis. Samples were annealed at 600 °C for different durations. Figure 6.27 shows results from 88 nm SOI samples (top) and bulk Si samples (bottom). The SOI samples show the same wider a/c interface as seen with the previous SOI series. The samples annealed for 50s, 60s, and 65s all have downslopes with similar gradients. A linear fit through the slopes illustrates this point more clearly. The slope 163 c) 100nm SOI, PAI, 1keV BF 2 Figure 6.26 MEIS energy spectra from BF2 samples a) bulk Si, b) 60 nm SOI, and c) 100 nm SOI. In all cases the wafers were pre amorphised with 40 keV Xe to a fluence of 1E14 cm -2 . In a) and b) samples were implanted with 3 keV BF2 and in c) with 1 keV BF2. Samples were annealed at various temperatures, as indicated.
ecomes steeper for the sample annealed for 70s, around the depth of the high As concentration. In comparison, the bulk samples have downslopes that are generally steeper and become steeper as the thickness of the amorphous layer decreases. This behaviour is as expected for a sharp interface when accounting for energy straggling. As an example to illustrate the differences in amorphous crystalline interfaces between the two wafer types, a comparison of the bulk sample annealed for 30s, that has an amorphous layer thickness of ~ 17 nm, with the SOI sample annealed for 65s, that has an amorphous layer thickness of ~ 11nm (based on FWHM), shows that the SOI sample has a ~ 50% less steep gradient, despite the reduced amorphous layer width. Yield (counts per 5µC) 550 500 450 400 350 300 250 200 150 100 50 5500 500 450 400 350 300 250 200 150 100 50 40 keV Xe 1E14, 3 keV As 2E15 20 15 10 5 Si depth (nm) 20 15 10 5 Si depth (nm) 0 68 70 72 74 76 78 80 82 84 86 88 90 92 94 Energy (keV) 164 SOI as-impl SOI 600C 50s SOI 600C 60s SOI 600C 65s SOI 600C 70 s SOI 600C 200s As depth (nm) 10 5 0 random Bulk 600C 30s Bulk 600C 40s Bulk 600C 50s Bulk 600C 60s Bulk 600C 70s Bulk 600C 200s As depth (nm) 10 5 0 Figure 6.27 MEIS energy spectra for SOI (top) and Bulk Si (bottom) wafers. Samples were pre-amorphised, implanted with 3 keV As to 2E15 and annealed at 600 °C for various times.
- Page 131 and 132: no longer “visible” in MEIS has
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- Page 137 and 138: Chapter 6 Annealing studies 6.1 Int
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- Page 157 and 158: duration, is observed. MEIS results
- Page 159 and 160: Yield (counts per 5µC) 500 400 300
- Page 161 and 162: ack edges of the Si peaks are very
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- Page 165 and 166: R s (Ω/sq) 950 900 850 800 750 60
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- Page 189 and 190: 6.5 Conclusion In summary, in this
- Page 191 and 192: 20 L. Capello, T. H. Metzger, M. We
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ecomes steeper for the sample annealed for 70s, around the depth <strong>of</strong> the high As<br />
concentrat<strong>ion</strong>. In comparison, the bulk samples have downslopes that are generally<br />
steeper <strong>and</strong> become steeper as the thickness <strong>of</strong> the amorphous layer decreases. This<br />
behaviour is as expected for a sharp interface when accounting for <strong>energy</strong> straggling. As<br />
an example to illustrate the differences in amorphous crystalline interfaces between the<br />
two wafer types, a comparison <strong>of</strong> the bulk sample annealed for 30s, that has an<br />
amorphous layer thickness <strong>of</strong> ~ 17 nm, with the SOI sample annealed for 65s, that has<br />
an amorphous layer thickness <strong>of</strong> ~ 11nm (based on FWHM), shows that the SOI sample<br />
has a ~ 50% less steep gradient, despite the reduced amorphous layer width.<br />
Yield (counts per 5µC)<br />
550<br />
500<br />
450<br />
400<br />
350<br />
300<br />
250<br />
200<br />
150<br />
100<br />
50<br />
5500<br />
500<br />
450<br />
400<br />
350<br />
300<br />
250<br />
200<br />
150<br />
100<br />
50<br />
40 keV Xe 1E14, 3 keV As 2E15<br />
20 15 10 5<br />
Si depth (nm)<br />
20 15 10 5<br />
Si depth (nm)<br />
0<br />
68 70 72 74 76 78 80 82 84 86 88 90 92 94<br />
Energy (keV)<br />
164<br />
SOI as-impl<br />
SOI 600C 50s<br />
SOI 600C 60s<br />
SOI 600C 65s<br />
SOI 600C 70 s<br />
SOI 600C 200s<br />
As depth (nm)<br />
10 5 0<br />
r<strong>and</strong>om<br />
Bulk 600C 30s<br />
Bulk 600C 40s<br />
Bulk 600C 50s<br />
Bulk 600C 60s<br />
Bulk 600C 70s<br />
Bulk 600C 200s<br />
As depth (nm)<br />
10 5 0<br />
Figure 6.27 MEIS <strong>energy</strong> spectra for SOI (top) <strong>and</strong> Bulk Si (bottom) wafers. Samples were<br />
pre-amorphised, implanted with 3 keV As to 2E15 <strong>and</strong> annealed at 600 °C for various times.
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