njit-etd2000-029 - New Jersey Institute of Technology

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21 The fundamental reaction pathways and kinetics have been investigated for only a few well characterized, industrially important systems. These include silane chemistry (pertinent to this study and discussed in detail in the experimental procedure) and thus silicon deposition, free-radical reactions, and intramolecular reactions of organometallic compounds. 1.1.2.5 Reaction Mechanism in CVD: Adsorption, surface reaction and desorption are important steps in the CVD process, which need to be understood properly in order to be able to explain the reaction mechanism. • Adsorption and Desorption: CVD reactions being surface catalyzed, reactants adsorb on the surface. The simplest expression for the amount of a gas adsorbed on a surface, is given by the Langmuir Adsorption Isotherm34 as: where: 0 = fraction of the total sites adsorbed by the gas, P = pressure of the gas, K = equilibrium adsorption constant for the gas. In CVD reactions, many times, both the reacting species adsorb onto the surface, thereby resulting in what is known as competitive adsorption. The adsorption isotherm in this case is given by: where: OA, OB = fraction of total sites covered by species A and B, KA, KB = equilibrium adsorption constant for species A and B,
22 • Reaction: The surface catalyzed reaction in a CVD process is usually a bimolecular reaction between the two adsorbed species. In that case, the rate of the reaction is dependent on the concentration or the fraction of the sites occupied by each of the species. If this reaction is the rate determining step, which it usually is, the rate of film deposition can be given as: This method of treating a surface catalyzed reaction is known as the Langmuir- Hinshelwood kinetics34. If one of the pressures is maintained constant and the other is varied, the rate first increases, passes through a maximum and then decreases. The falling off of the rate at high pressures can be explained to be due to the fact that one reactant displaces the other reactant, as its pressure is increased. Two special cases of equation 1.3 are34 : 1) Sparsely covered surfaces, where both PA and PB are sufficiently low (due to dilution or very high vacuum), for the pressure terms in the denominator to be neglected, so that the rate equation (1.3) becomes, 2) When reactant A is weakly adsorbed (i.e. KA > 1, we have,
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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 and 40: 18 Figure 1.1 Scheme to show the tr
Page 41: 20 the low-pressure operation. Dry
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
Page 91 and 92: 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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