njit-etd2000-029 - New Jersey Institute of Technology

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19 flow rate, and the total pressure of the source determine the amount of reagent transported from the bubbler. In this study, a carrier gas is not needed because of the high vapor pressure of DES and the low pressure nature of the deposition. The need for films with reproducible and controllable optical, electrical, and mechanical properties means that CVD reagents must be pure, must not produce byproducts that incorporate into the growing film or interact with gas handling and reactor construction materials. There are a wide variety of CVD reactor geometries used to accommodate the many CVD applications. These include horizontal reactor, vertical reactor, barrel reactor, pancake reactor, and multiple-wafer-in-tube LPCVD reactor. Essentially, this study involves a multiple-wafer-in-tube LPCVD (low pressure chemical vapor deposition) reactor. LPCVD is the main production tool for polycrystalline silicon films, especially for the films used in the microelectronics industry 19-21. A typical configuration for this reactor is shown in Figure 2.2. This reactor operates around 0.5 Torr and wall temperatures are approximately equal to those of the deposition surfaces. The main advantage of LPCVD is that is allows a large number of substrates to be coated simultaneously while maintaining film uniformity. This is a result of the large diffusion coefficient at low pressures, which makes the growth rate limited by the rate of surface reactions rather than the rate of mass transfer to the substrate. Finally, the exhaust system treats the effluents so that hazardous byproducts are disposed of in a safe and environmentally sound manner. Mechanical pumps are typically added for
20 the low-pressure operation. Dry and wet chemical scrubbers, as well as pyrolysis units, are used to clean up the reactor effluent. 1.1.2.3 Nucleation and Growth: The growth of a thin film by CVD is initiated by exposing a substrate to the film precursors in the reactor. The resulting growth and microstructure of the film is determined by surface diffusion and nucleation processes on the growth interface, which are influenced by the substrate temperature, reactor pressure, and gas-phase composition. An amorphous film is formed at low temperatures and high growth rates when the surface diffusion is slow relative to the arrival of film precursors. At high temperatures and low growth rates, the surface diffusion is fast relative to the incoming flux, allowing the adsorbed species to diffuse to step growth and to form epitaxial layers replicating the substrate lattice. Nucleation occurs at many different points on the surface at intermediate temperatures and growth rates. Adsorbed species then diffuse to the islands which grow and coalesce to form a polycrystalline film. The presence of impurities increases the nucleation density. CVD film growth modes may be characterized in terms of three main growth models for thin films: Volmer-Weber growth (three-dimensional island growth), Franck-van der Merwe growth (two-dimensional layer by layer), and Stranski-Krastanov growth (layer plus island)33 . 1.1.2.4 Chemical Reactions and Kinetics: The versatility of the CVD technique is demonstrated through the multitude of films synthesized by various reaction schemes, including pyrolysis, reduction, oxidation, and disproportionation of the reactants. The underlying chemistry is typically a complex mixture of gas-phase and surface reactions.
Page 1 and 2: Copyright Warning & Restrictions Th
Page 3 and 4: ABSTRACT SYNTHESIS AND CHARACTERIZA
Page 5 and 6: SYNTHESIS AND CHARACTERIZATION OF L
Page 7 and 8: APPROVAL PAGE SYNTHESIS AND CHARACT
Page 9 and 10: This thesis is dedicated to my pare
Page 11 and 12: TABLE OF CONTENTS Chapter Page 1 IN
Page 13 and 14: TABLE OF CONTENTS (Continued) 2.6 A
Page 15 and 16: TABLE OF CONTENTS (Continued) Chapt
Page 17 and 18: LIST OF TABLES Table Page 1.1 Evapo
Page 19 and 20: LIST OF FIGURES (Continued) 4.2 Fil
Page 21 and 22: LIST OF FIGURES (Continued) 4.43 SE
Page 23 and 24: 2 of transistors on a chip would co
Page 25 and 26: 4 Typically, light beams do the etc
Page 27 and 28: Having the technology to transfer t
Page 29 and 30: 8 capacitance of the wire. It may s
Page 31 and 32: 10 side of the chip to the other. O
Page 33 and 34: metal/oxide/semiconductor integrate
Page 35 and 36: 14 properties of the film obtained
Page 37 and 38: 16 Chemical vapor deposition is dis
Page 39: 18 Figure 1.1 Scheme to show the tr
Page 43 and 44: 22 • Reaction: The surface cataly
Page 45 and 46: 24 If the deposition process is lim
Page 47 and 48: 26 1.2 Types of CVD Process As ment
Page 49 and 50: 28 Lowering the gas pressure by abo
Page 51 and 52: 30 purity and density, controllable
Page 53 and 54: 32 to block alkali ions. All films
Page 55 and 56: 34 Some of the attractive propertie
Page 57 and 58: 36 1.5 Refractory Materials Ceramic
Page 59 and 60: 38 deposited and then a conducting
Page 61 and 62: 40 Table 1.7 Physical properties of
Page 63 and 64: 42 In Chapter 2, a review of litera
Page 65 and 66: Material Melting Temperature (°C)
Page 67 and 68: 46 The reaction involving BCl 3 for
Page 69 and 70: 48 B2H6 + 2NH3 = 2BN + 6H2 Rand et
Page 71 and 72: 50 ammonia at 250° - 600°C in an
Page 73 and 74: 52 2.3.1 Synthesis by CVD and LPCVD
Page 75 and 76: 54 temperature range of 700-1300 K
Page 77 and 78: 56 The refractive index of c-BN was
Page 79 and 80: 58 the problem to hydrogen content
Page 81 and 82: 60 Many researchers 70,69,82 have s
Page 83 and 84: 62 BN film coatings are useful to i
Page 85 and 86: 64 2.5.1 Dielectric Thin Films With
Page 87 and 88: 66 A family of thermally stable, lo
Page 89 and 90: 68 suggested that the there is a ch
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70 a heavily dependent on process c
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72 Typically thin beryllium or poly
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Figure 2.2 Trends in ULSI miniaturi
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76 Figure 2.3 Basic SCALPEL princip
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78 50 nanometers and smaller. The r
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80 A large number of materials have
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82 2.7 Aim and Scope of the Present
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84 jacket maintained the temperatur
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86 Figure 3.2 Schematic diagram of
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88 contamination and hence requires
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90 known reaction chamber volume. T
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92 all the experiments. The boat wa
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94 limited by sample surface and a
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96 3.5.6 Film Stress Stress develop
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98 3.5.7 X-Ray Diffraction (XRD) A
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100 where hγ , Eg(opt) and K 1 den
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102 technique. However the films we
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104 same film surface. Such measure
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106 the device, an electrical conta
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108 Figure 3.5 Process flow diagram
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110 samples. The recombination-gene
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112 3.7.2 Characterization of B-N-C
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114 In all the experiments, films d
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116 operating in the mass transfer
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118 variation in the NH3/TEAB flow
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120 mode, and a small peak close to
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122 infrared absorption spectra, no
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124 increasing the NH3/TEAB flow ra
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126 tensile behavior with increase
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128 material with the electrons jum
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130 while at a constant temperature
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132 4.4.6 Electrical Characterizati
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134 4.4.6.2 Investigation of LPCVD
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136 Figure 4.17 C-V curve shift alo
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138 Figure 4.18 Capacitance-Voltage
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140 Thus by knowing the refractive
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142 rate of 40 sccm, as the Power w
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144 4.4.7.2 Characterization of B-N
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146 the reactant species in eq. 4.2
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148 Figure 4.25 Variation of Film C
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150 Figure 4.27 Plot of growth rate
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152 4.5.3 Rate Equation Knowing the
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154 4.5.4 Reaction Mechanism In the
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156 high TiC14 coverage. ΘTiC13 ca
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158 Figure 4.30 shows a typical XPS
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160 degraded. Hence, films with thi
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162 Figure 4.35 Variation in film d
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164 Figure 4.37 Variation in film r
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166 emittance increased; the transm
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Figure 4.41 SEM micrograph of TiN d
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Figure 4.4 3 SEM micrograph of TiN
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172 Orientation (hid) Table 4.1 Com
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174 carried out under the same proc
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176 was not in a compound form. It
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REFERENCES 1. R. Turton. 1995. The
Page 201 and 202:
180 36. W. Kern and V. S. Ban, "Che
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182 74. L. Imhoff, A. Bouteville, a
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