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

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4.2.2.3 Experimental output As mentioned previously, by changing the voltage applied to the analyser and piecing together separate data tiles a complete 2D yield with energy and scattering angle spectrum is produced. An example is shown in Figure 4.15 which was taken from an As implanted Si sample. The different colours represent different scattering yields. Taking a cross section of the data along the angular axis produces the yield vs scattering angle spectrum, as shown in the top right graph. There are two dips in the spectrum which correspond to the [332] and [111] blocking directions. There is also a peak corresponding to the O peak. Taking a cross section along the energy axis at the angles of these blocking directions produces energy spectra of the [332] and [111] directions as shown in the bottom graph. Energy keV As Si O [332] [111] Scattering angle θ Yield yield (per 5uC) 800 700 600 500 400 300 200 100 200 150 100 0 55 60 65 70 75 50 0 85 Angular scan O [332] O Scattering Angle Energy spectrum Si [111] As 332 111 140 150 160 170 180 190 200 Energy (keV) Figure 4.15 MEIS 2D data output (left) of an As implanted Si sample. Indicated is the position of the angular cut and the two cuts along the energy axis of the [332] and [111] blocking dips. The corresponding angular spectrum is plotted in the top right of the figure and the corresponding energy spectra are given in the bottom right of the figure.
4.2.2.4 Interpretation of spectra An example set of MEIS spectra is shown in Figure 4.16. These are taken with a nominally 100 keV He beam. The samples were aligned along the [īīı] axis and the data is taken from the [111] blocking direction. Data is taken for a virgin sample, an amorphous sample (random), a sample implanted with 3 keV As to a fluence of 2E15 and a sample with the same implant that has been annealed to 550 °C for 200s. Using the kinematic factors enables the energy for scattering off surface As, Si and O to be determined. The corresponding extra energy loss with respect to these reference energies with scattering depth, have been calculated and the resulting depth scales have been added to the figure. Considering first the data from the virgin Si sample, two peaks are present. These correspond to scattering off surface Si and O atoms. The Si peak consists mainly of scattering off Si atoms in the amorphous SiO2 layer. Deeper atoms in crystalline positions do not give rise to backscattering because of shadowing. A small background yield is due to dechannelling. The O peak is superimposed on this background yield. The effects, on the shape of the peaks, of the system resolution and energy straggling can be seen. System resolution is responsible for the slope of the high energy leading edge. A combination of the system resolution and energy straggling is largely responsible for the low energy downslope. Isotopes of Si cause a small extension of the peak in the energy 84 – 85 keV. This occurs for all samples and convolution causes it to become a small tail. The random spectrum is modified considerably compared with the virgin, as can be seen with the dramatically higher scattering yield of the Si peak. Because the atoms are not on regular lattice sites there is scattering off deeper atoms, giving rise to the high scattering yield. The O peak is on top of this Si signal. The as-implanted sample shows that the implant causes the Si to be amorphised, as evidenced by the height of the Si peak reaching the random yield. The width of this amorphous layer is taken at the FWHM and is approximately 11 nm. The As peak is also visible in the spectrum at higher energy. Annealing of the sample causes SPER. This reduces the width of the amorphous layer. The As profile is also modified. This shows how MEIS is able to profile Si damage and dopant profiles simultaneously. Annealing studies are contained in chapter 6 of this thesis. 86
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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
Page 53 and 54: On the basis that by creating an in
Page 55 and 56: Figure 3.4 Structure of crystalline
Page 57 and 58: a Si atom will suffer little angula
Page 59 and 60: 3.2.2.5 Homogeneous model (Critical
Page 61 and 62: Sputtering and atomic mixing play a
Page 63 and 64: and is approximately 25 times faste
Page 65 and 66: elevant dopants later. For equal co
Page 67 and 68: nearest neighbour distance (52). By
Page 69 and 70: Category I defects are produced whe
Page 71 and 72: thermal annealing (600 - 700 °C an
Page 73 and 74: 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: Figure 4.14 Illustration of the dou
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 and 126: damage evolution behaviour observed
Page 127 and 128: Yield (counts per 5 µC) 250 200 15
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
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interface, as evidenced by the high
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duration, is observed. MEIS results
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Yield (counts per 5µC) 500 400 300
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ack edges of the Si peaks are very
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underneath the SiO2 layer, iii) it
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R s (Ω/sq) 950 900 850 800 750 60
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As concentration (at/cm 3 ) 1E22 1E
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R s (Ω/sq) 950 900 850 800 750 70
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Following annealing it was observed
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∆a/a (x 10 -3 ) 4,0 epi550 3,5 3,
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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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