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 ...
Concentration (at/cm 3 ) a) Concentration (at/cm 3 ) b) 1E22 1E21 1E20 1E19 1E18 1E17 as-implanted non PAI PAI 1E16 0 20 40 60 PAI minus non PAI , 3 keV BF . B profiles 2 1E20 600C PAI 950C PAI 1000C PAI 1025C PAI 1130C PAI 1E19 8 10 12 14 16 18 20 22 Depth (nm) non PAI and PAI, 3 keV BF 2 . B profiles 600°C 20 mins non PAI PAI 0 20 40 60 0 20 40 60 0 20 40 60 80 Depth (nm) Returning to the interaction between implanted species, in the pre amorphised annealed samples there is an additional B peak formed, centred around 13 – 14 nm, Figure 7.7a). This is not present in the non pre-amorphised samples. B is trapped at roughly the same depth as the trapped Xe and F. This occurs for all anneals. The 600 °C PAI has the B peak superimposed on the back edge of the main peak, making it appear to be a broader layer and not a separate peak. Subtraction of the non PAI spectra from 183 1000°C 5s non PAI PAI 1130°C spike non PAI PAI Figure 7.7 a) SIMS B depth profiles for Si implanted with 3 keV BF2 with and without Xe pre-amorphisation, as-implanted, and after anneals of 600 °C 20mins, 1000 °C 5s and 1130 °C spike. b) B profiles from PAI samples with the corresponding non PAI profiles subtracted, showing the trapped B. 10 9 10 8 10 7 10 6 10 5 10 4 10 3 Secondary Ion Counts (cts/sec)
the corresponding PAI sample, yields a clear peak shape similar to the rest of the anneals, as shown in Figure 7.7b). Integration of the B peaks in Figure 7.7b) shows that the amount of B in the trapped peak goes down with increasing annealing temperature. Starting from 4E20 cm -3 for the 600 °C sample, the amount falls to 3.03E20 cm -3 for 950 °C, 2.63E20 cm -3 for 1000 °C, 1.46E20 cm -3 for 1025 °C and 1E20 cm -3 for the sample annealed at 1130 °C. As a B peak is formed with the 600 °C sample it is clear that some B has to have moved in deeper to form the trapped peak during SPER. The B peak formation is therefore not associated with trapping during B diffusion. In fact the amount of trapped B, shown in Figure 7.7b) goes down in the samples where there is more diffusion and so it would indicate that some of the trapped B dissolves during high temperature annealing. Comparison with the amount of accumulated F at the same depth shows that initially there is four times the amount of trapped F to B. The amount of F trapped has less variation with temperature than B and so for the 1130 °C sample there is approximately 14 times more trapped F than B. The combined behaviour is shown in Figure 7.8, with the SIMS F and B profile overlaid on top of the MEIS Xe profile, for the 3 keV 1000 °C 5s and 1130 °C spike samples. a) b) Yield (counts per 5 µC) 20 15 10 5 20 keV Xe, 3keV BF 2 F - 1000C 5s B - 1000C 5s Xe - 1000C 5s 0 0.0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Depth (nm) 2.0x10 20 1.5x10 20 1.0x10 20 5.0x10 19 Concentration (atoms cm -3 ) Since noble gases, including Xe have previously been observed to form bubbles in Si (12-15), the possible formation of Xe agglomerates or bubbles was checked using EFTEM experiments. Figure 7.9a) shows cross sectional EFTEM images using electrons that have undergone a ~ 670 eV loss (M excitation edge of Xe) for a Xe PAI, 3 keV BF2 implanted sample, annealed to 1025 °C. Any Xe present appears as a bright area. To check that the areas indeed represent Xe, an image using N excitation edge electrons (~65 eV loss) was taken and is shown in Figure 7.9b). Both figures show the Yield (counts per 5 µC) 184 20 15 10 5 20 keV Xe, 3keV BF 2 F - 1130C spike B - 1130C spike Xe - 1130C spike 0 0.0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Depth (nm) Figure 7.8 Combined MEIS Xe depth profiles with SIMS F and B depth profiles overlaid, for a) 1000 °C 5s and b) 1130 °C spike samples. 2.0x10 20 1.5x10 20 1.0x10 20 5.0x10 19 Concentration (atoms cm -3 )
- Page 151 and 152: The as-implanted sample, with a bro
- Page 153 and 154: a) b) Yield (counts per 5 µC) Yiel
- Page 155 and 156: interface, as evidenced by the high
- 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
- Page 163 and 164: underneath the SiO2 layer, iii) it
- Page 165 and 166: R s (Ω/sq) 950 900 850 800 750 60
- Page 167 and 168: As concentration (at/cm 3 ) 1E22 1E
- Page 169 and 170: R s (Ω/sq) 950 900 850 800 750 70
- Page 171 and 172: Following annealing it was observed
- Page 173 and 174: ∆a/a (x 10 -3 ) 4,0 epi550 3,5 3,
- Page 175 and 176: Yield (counts per 5 uC) 350 300 250
- Page 177 and 178: (FWHM). Concomitantly, As in the re
- Page 179 and 180: Yield (counts per 5 µC) 450 400 35
- Page 181 and 182: The higher temperature anneals carr
- Page 183 and 184: ecomes steeper for the sample annea
- Page 185 and 186: Figure 6.28 Schematic illustrations
- Page 187 and 188: and the 2D picture in Figure 6.31b)
- Page 189 and 190: 6.5 Conclusion In summary, in this
- Page 191 and 192: 20 L. Capello, T. H. Metzger, M. We
- Page 193 and 194: egarding B profiles relevant to the
- Page 195 and 196: Yield (counts per 5 µC) 400 300 20
- Page 197 and 198: TRIM AU 0.04 0.03 0.02 0.01 TRIM si
- Page 199 and 200: a) F profile PAI 3 keV BF2 b) F pro
- Page 201: Yield (counts per 5 µC) 20 15 10 5
- Page 205 and 206: amorphous matrix, (16) i.e. local c
- Page 207 and 208: 21 M. Anderle, M. Bersani, D. Giube
- Page 209 and 210: stopped at depths beyond the observ
- Page 211: the role of each individual element
Concentrat<strong>ion</strong> (at/cm 3 )<br />
a)<br />
Concentrat<strong>ion</strong> (at/cm 3 )<br />
b)<br />
1E22<br />
1E21<br />
1E20<br />
1E19<br />
1E18<br />
1E17<br />
as-implanted<br />
non PAI<br />
PAI<br />
1E16<br />
0 20 40 60<br />
PAI minus non PAI , 3 keV BF . B pr<strong>of</strong>iles<br />
2<br />
1E20<br />
600C PAI<br />
950C PAI<br />
1000C PAI<br />
1025C PAI<br />
1130C PAI<br />
1E19<br />
8 10 12 14 16 18 20 22<br />
Depth (nm)<br />
non PAI <strong>and</strong> PAI, 3 keV BF 2 . B pr<strong>of</strong>iles<br />
600°C 20 mins<br />
non PAI<br />
PAI<br />
0 20 40 60 0 20 40 60 0 20 40 60 80<br />
Depth (nm)<br />
Returning to the interact<strong>ion</strong> between implanted species, in the pre amorphised<br />
annealed samples there is an addit<strong>ion</strong>al B peak formed, centred around 13 – 14 nm,<br />
Figure 7.7a). This is not present in the non pre-amorphised samples. B is trapped at<br />
roughly the same depth as the trapped Xe <strong>and</strong> F. This occurs for all anneals. The 600 °C<br />
PAI has the B peak superimposed on the back edge <strong>of</strong> the main peak, making it appear<br />
to be a broader layer <strong>and</strong> not a separate peak. Subtract<strong>ion</strong> <strong>of</strong> the non PAI spectra from<br />
183<br />
1000°C 5s<br />
non PAI<br />
PAI<br />
1130°C spike<br />
non PAI<br />
PAI<br />
Figure 7.7 a) SIMS B depth pr<strong>of</strong>iles for Si implanted with 3 keV BF2 with <strong>and</strong> without Xe<br />
pre-amorphisat<strong>ion</strong>, as-implanted, <strong>and</strong> after anneals <strong>of</strong> 600 °C 20mins, 1000 °C 5s <strong>and</strong><br />
1130 °C spike. b) B pr<strong>of</strong>iles from PAI samples with the corresponding non PAI pr<strong>of</strong>iles<br />
subtracted, showing the trapped B.<br />
10 9<br />
10 8<br />
10 7<br />
10 6<br />
10 5<br />
10 4<br />
10 3<br />
Secondary Ion Counts (cts/sec)
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