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acquired were converted into damage depth distributions in terms of number of displaced Si atoms or dopant atoms cm -3 , using a standard calibration procedure (22). The backscattered ion yield was referenced to the random level measured on a Si sample, amorphised by high dose self ion bombardment. In addition the energy scales were converted into depth scales using established inelastic energy loss data (23) and applying the surface approximation (22, 24). Implanted As / Sb and displaced Si distributions can be detected down to levels of ~ 1 × 10 19 cm -3 and 10 21 cm -3 , respectively. Additional SIMS As profiles were obtained in an Atomika 4500 instrument at IMEC using a 0.5 keV 02 + primary beam at normal incidence. In these measurements a crater size of 250 µm was used and mass Si 30 was monitored to ensure a better than 1% current stability. Depth scale calibration relied on a constant ion beam current and was performed using the erosion rate obtained on one deep crater in combination the erosion time for each crater. Relative sensitivity factors (RSF, from implant standard) were repeatable within 1%. 5.3 Results and discussion Considering first the damage evolution during As ion bombardment, a series of Si samples was implanted through the native oxide with 2.5 keV As ions to doses ranging from 3 × 10 13 to 1.8 × 10 15 cm -2 . The dose dependence of the MEIS spectra obtained for these samples is shown in Figure 5.1. Peaks resulting from the As implant, the displaced Si atoms and the oxide, respectively, are indicated in the figure. For comparison Figure 5.1 also contains the spectrum for a virgin Si sample as well as a random spectrum. The virgin Si sample shows two peaks due to scattering off Si (edge at 171 keV) and O atoms (edge at 153 keV) both contained in the native oxide. The thickness of the native oxide thickness is calculated as ~1.5 nm. It should be noted however that in the case of the Si peak there is also a contribution from disordered Si atoms at the oxide / Si interface (19, 25). The virgin spectrum is the base against which any additional backscattering from displaced Si atoms that results from the As implant is measured. The figure shows the changes in the energy spectrum in terms of the growth of the As and Si scattering peaks for increasing As implant dose. It is seen that the Si damage peak and also the As peak, spread towards lower energies, i.e. greater depths, although the movement of the latter is less pronounced. 107
Yield (counts per 5 µC) 250 200 150 100 50 O Si edge 0 150 160 170 180 190 Energy (keV) This development of these peaks is more clearly visible after conversion of the spectra to the depth profiles of As and of displaced Si atoms. The results are shown in Figure 5.2. The use of logarithmic concentration scales in these profiles depicts more clearly the effects of the As implant dose changes that cover nearly two decades. The depth profiles of the displaced Si atoms (top) were obtained after subtraction of the virgin surface peak (shown separately in the figure) and hence represent the distributions of the additional damage after each implanted As dose. The common depth scale illustrates the correlation between implant and displaced Si. The evolution of these two sets of peaks shows an unexpected behaviour for both the growth of the damage and the accumulation of the dopant. 108 As virgin 3E13 9E13 4E14 1.5E15 1.8E15 random Figure 5.1 MEIS energy spectra showing the growth of the Si damage and As dopant yield as a function of fluence for 2.5 keV As + ion implantation into virgin Si at room temperature.
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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
Page 75 and 76: defect pairs due to Coulomb attract
Page 77 and 78: ⎛ 〈 C ⎞ ⎛ ⎞ I 〉 〈 C V
Page 79 and 80: 27 R.D. Goldberg, J. S. Williams, a
Page 81 and 82: 67 H. Bracht. Diffusion Mechanism a
Page 83 and 84: Hall effect measurements were carri
Page 85 and 86: energy than one scattered from an a
Page 87 and 88: epresents a small improvement over
Page 89 and 90: (dE/dx)out multiplied by the path l
Page 91 and 92: they are small compared to the diff
Page 93 and 94: ackscattering (27). This fact forms
Page 95 and 96: Figure 4.7 a) Plot of a Gaussian di
Page 97 and 98: similar to the width of the error f
Page 99 and 100: UP Ion Beam SPIN Rotation Sample Sc
Page 101 and 102: Kinematic factor (K) 1.0 0.8 0.6 0.
Page 103 and 104: Figure 4.14 Illustration of the dou
Page 105 and 106: 4.2.2.4 Interpretation of spectra A
Page 107 and 108: with are comparatively small, ~ 0.5
Page 109 and 110: Inelastic energy loss (eV/Ang) 32 2
Page 111 and 112: iterative procedure is carried out
Page 113 and 114: Yield (couts per 5µC) 300 250 200
Page 115 and 116: SIMS experiments were also carried
Page 117 and 118: MEIS, using the scattering conditio
Page 119 and 120: 4.5 Sample production Samples have
Page 121 and 122: an N2/O2 environment to maintain an
Page 123 and 124: 38 M. Anderle, M. Barozzi, M. Bersa
Page 125: damage evolution behaviour observed
Page 129 and 130: essentially a “zero dose” profi
Page 131 and 132: no longer “visible” in MEIS has
Page 133 and 134: yield (cts / 5µC) 500 400 300 200
Page 135 and 136: 5.4 Conclusion MEIS analysis with a
Page 137 and 138: Chapter 6 Annealing studies 6.1 Int
Page 139 and 140: 6.2.2.2 Results and Discussion Figu
Page 141 and 142: theory predictions and X-ray fluore
Page 143 and 144: 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
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(FWHM). Concomitantly, As in the re
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Yield (counts per 5 µC) 450 400 35
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The higher temperature anneals carr
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ecomes steeper for the sample annea
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Figure 6.28 Schematic illustrations
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and the 2D picture in Figure 6.31b)
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6.5 Conclusion In summary, in this
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20 L. Capello, T. H. Metzger, M. We
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egarding B profiles relevant to the
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Yield (counts per 5 µC) 400 300 20
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TRIM AU 0.04 0.03 0.02 0.01 TRIM si
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a) F profile PAI 3 keV BF2 b) F pro
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Yield (counts per 5 µC) 20 15 10 5
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the corresponding PAI sample, yield
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amorphous matrix, (16) i.e. local c
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21 M. Anderle, M. Bersani, D. Giube
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stopped at depths beyond the observ
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the role of each individual element
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