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

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Approximately half of the nominal 2×10 14 cm -2 implanted Xe appears to be contained within the peak. The remainder is assumed to have diffused out. Yield (counts per 5 µC) 20 15 10 5 0 20 15 10 5 0 20 keV Xe PAI, 3 keV BF 2 as implanted 600 C 20 min 1000 C 5s 1130 C spike 20 keV Xe PAI, 1 keV BF 2 0 2 4 6 8 10 12 14 16 18 Depth (nm) Since the depth of the Xe accumulation is closely related to the energy (hence depth) of the BF2 + implant into the amorphous Si, it was also interesting to study the behaviour of the F and B. TRIM calculations show that for the low BF2 implant energies used in this study, B and F projectiles have similar ranges. The depth profiles of 1.16 keV F, 0.67 keV B, 0.39 keV F and 0.22 keV B, corresponding to 3 and 1 keV BF2 implants, respectively, are shown in Figure 7.3. For 3 keV BF2 + the mean projected range (Rp) of F is ~ 4.7 nm, and for 1 keV ~ 2.3 nm. The depth of the Xe accumulation is close to 3 × Rp i.e. towards the end of the B and F ranges. 177 as implanted 600 C 20 min 1000 C 5s 1050 C spike 2.0x10 20 1.5x10 20 1.0x10 20 5.0x10 19 0.0 2.0x10 20 1.5x10 20 1.0x10 20 5.0x10 19 Figure 7.2 MEIS Xe depth profiles for Xe pre-amorphised Si samples, implanted with 3 keV BF2 (top) and 1 keV BF2 (bottom), as-implanted and after different anneals. 0.0 Xe concentration (at/cm 3 )
TRIM AU 0.04 0.03 0.02 0.01 TRIM simulation of B and F range in 1 & 3 keV BF 2 implants 0.22 keV B - R = 1.93 nm p 0.39 keV F - R = 2.14 nm p 0.67 keV B - R = 4.15 nm p 1.16 keV F - R = 4.42 nm p 0.00 0 5 10 15 Depth (nm) SIMS analysis was used for detecting F and B since the sensitivity of MEIS for low Z elements is relatively small and any scattering at the F and B concentrations present would be contained within the noise level of the Si background. Figure 7.4a) shows SIMS depth profiles for F, from pre-amorphised samples, as-implanted and after various anneals. Figure 7.4b) shows F depth profiles from the non pre-amorphised samples. The BF2 implant energy was 3 keV. Note that the use of SIMS for ultra shallow junction profiling has some inherent difficulties in the first few nanometres, caused by changing sputtering rates until an equilibrium erosion rate has been reached. This can cause some inaccuracies to the depth scale and concentration calibration in the first couple of nanometres (22). Disregarding a sharp spike within the first 2 nm that is probably a SIMS surface artefact, the as-implanted samples shows profiles with maxima that are in close agreement with the TRIM calculation. The PAI samples are considered first. After annealing there has been F migration to the surface, yielding a F surface peak within the first 3 – 4 nm. (The concentration these may be partially influenced by SIMS artefacts). For the preamorphised samples there is the additional migration of some of the F deeper in, forming a second peak. An ~6 nm wide peak (FWHM) centred around 12 – 13 nm is found. This depth recurs for all the anneal conditions, with a slightly wider distribution for the 600 °C sample compared to the higher temperatures. Integration of the second 178 0.22 keV B 0.39 keV F 0.67 keV B 1.16 keV F Figure 7.3 TRIM depth profiles for B and F from 1 and 3 keV BF2 implants.
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Damage formation and annealing stud
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3.2.2.6 Other models 40 3.2.3 Other
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Chapter 7 Interaction between Xe, F
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List of Figures Figure 1.1 a) Schem
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Figure 4.13 Variation in the kinema
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Figure 6.10 MEIS energy spectra for
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Figure 7.8 Combined MEIS Xe depth p
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Abbreviations and Symbols a/c amorp
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Abstract The work described in this
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Chapter 7 5 M. Werner, J.A. van den
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terminal (Vg), current cannot flow
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This is an approximate average leve
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the active channel, adjacent to the
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To continue to improve devices ther
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produces a device quality regrown l
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technique of channelling Rutherford
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22 J.S Williams. Solid Phase Recrys
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and the probability of scattering t
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importance for many atomic collisio
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M1, V0, E0 Figure 2.2 Elastic scatt
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2.3.1 Models for inelastic energy l
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dE/dx (ev/Ang) 10 1 Inelastic Energ
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dE/dx (eV/Ang) 125 100 75 50 25 0 2
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Figure 2.5 Results of TRIM simulati
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Chapter 3 Damage and Annealing proc
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the Si/SiO2 interface, consuming th
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On the basis that by creating an in
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Figure 3.4 Structure of crystalline
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a Si atom will suffer little angula
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3.2.2.5 Homogeneous model (Critical
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Sputtering and atomic mixing play a
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and is approximately 25 times faste
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elevant dopants later. For equal co
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nearest neighbour distance (52). By
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Category I defects are produced whe
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thermal annealing (600 - 700 °C an
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Figure 3.11 Relationship between im
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defect pairs due to Coulomb attract
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⎛ 〈 C ⎞ ⎛ ⎞ I 〉 〈 C V
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27 R.D. Goldberg, J. S. Williams, a
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67 H. Bracht. Diffusion Mechanism a
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Hall effect measurements were carri
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energy than one scattered from an a
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epresents a small improvement over
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(dE/dx)out multiplied by the path l
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they are small compared to the diff
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ackscattering (27). This fact forms
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Figure 4.7 a) Plot of a Gaussian di
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similar to the width of the error f
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UP Ion Beam SPIN Rotation Sample Sc
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Kinematic factor (K) 1.0 0.8 0.6 0.
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Figure 4.14 Illustration of the dou
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4.2.2.4 Interpretation of spectra A
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with are comparatively small, ~ 0.5
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Inelastic energy loss (eV/Ang) 32 2
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iterative procedure is carried out
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Yield (couts per 5µC) 300 250 200
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SIMS experiments were also carried
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MEIS, using the scattering conditio
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4.5 Sample production Samples have
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an N2/O2 environment to maintain an
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38 M. Anderle, M. Barozzi, M. Bersa
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damage evolution behaviour observed
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Yield (counts per 5 µC) 250 200 15
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essentially a “zero dose” profi
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no longer “visible” in MEIS has
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yield (cts / 5µC) 500 400 300 200
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5.4 Conclusion MEIS analysis with a
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Chapter 6 Annealing studies 6.1 Int
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6.2.2.2 Results and Discussion Figu
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theory predictions and X-ray fluore
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implantation conditions are those u
Page 145 and 146: a) b) c) Yield (counts per 5 µC) Y
Page 147 and 148: greater than MEIS. SIMS is not sens
Page 149 and 150: attributed to the interference betw
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: Yield (counts per 5 µC) 400 300 20
Page 199 and 200: a) F profile PAI 3 keV BF2 b) F pro
Page 201 and 202: Yield (counts per 5 µC) 20 15 10 5
Page 203 and 204: the corresponding PAI sample, yield
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
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