CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

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CHAPTER 2. LITERATURE REVIEW Chemical vapor deposition of several electronic/magnetic thin film materials, i.e., Hafnium nitride (HfN), Nickel ferrite(NiFe2O4), Lithium ferrite (LiFe5O8), and Barium titanate (BaTiO3) has been investigated in this dissertation work. All these materials in thin film format exhibit certain attractive properties and can be promising material candidates for various high technology devices. In this chapter, a literature review of the physical properties, potential applications, and various previously reported thin film growth methods for each material is presented and especially the development of CVD related studies are emphasized. 2.1 Hafnium Nitride (HfN) 2.1.1 Physical Properties and Potential Applications Hafnium nitride (HfN), a transition metal nitride, has a rock salt structure with lattice constant of ~4.53Å (Fig.12). It possesses various superior properties, such as, low bulk resistivity (33µΩ∙cm), high melting point (3380˚C), high hardness and density, low work function (~4.8ev) and good chemical inertness [47-49]. Because of these excellent properties, HfN can be used as protective coatings on high speed cutting tools, field emission cathode, and gate electrode and Fig. 12. Unit cell of HfN crystal with cubic structure. 35
diffusion barrier material in microelectronic devices[50-52], for instance, the potential application of HfN as a gate electrode material in the metal–oxide–semiconductor field-effect transistor (MOSFET). It has been well known that the substitution of traditional gate oxide SiO2 with high-k material HfO2 can dramatically accelerate the scaling down of size of MOSFETs. However, coupling HfO2 with conventional gate electrode layer (poly silicon) will generate issues like boron penetration and the formation of a low-k interfacial layer, which will affect the performance of the whole device.[53] HfN can be a good candidate to replace poly silicon to work with HfO2 as a gate stack due to its excellent properties mentioned above. It has been found that equivalent oxide thickness (EOT) of HfO2-HfN gate stack can be scaled down to less than 1 nm with excellent leakage and long term reliability even after 1000˚C post metal annealing. Fig.13 below shows the well behaved electrical characteristics (Id-Vg, Id-Vd) of the n-MOSFET with an excellent subthreshold slope of 78 mV/dec. The as-used HfN film was deposited by DC magnetron sputtering of a Hf target in mixed Ar+N2 gas ambient. [52] Fig. 13. (a) Id-Vg and (b) Id-Vd characteristics of an n-MOSFET using HfN-HfO2 gate stack with EOT 1.18 nm. Reproduced with permission from ref. [52]. 2.1.2 Review of HfN Thin Film Growth Different methods of HfN thin film deposition have been investigated in the past few decades. Physical vapor deposition methods such as RF/DC magnetron sputtering [54-58], 36
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CHEMICAL VAPOR DEPOSITION OF THIN F
Page 3 and 4: ABSTRACT Chemical vapor deposition
Page 5 and 6: DEDICATION This dissertation is ded
Page 7 and 8: φ In-plane tilt angle of X-ray dif
Page 9 and 10: ACKNOWLEDGMENTS It is my pleasure t
Page 11 and 12: CONTENTS ABSTRACT .................
Page 13 and 14: 3.2.1 Introduction ................
Page 15 and 16: LIST OF TABLES Table 1. Hafnium ami
Page 17 and 18: indicated by the complex FMR curve.
Page 19 and 20: Fig. 49. Ferromagnetic resonance cu
Page 21 and 22: growth rate, good step coverage and
Page 23 and 24: growth of thin film oxides due to t
Page 25 and 26: one can uniformly deliver precursor
Page 27 and 28: for the next reaction step as shown
Page 29 and 30: Fig. 3. Schematic of a typical dire
Page 31 and 32: is predominantly dependent on syste
Page 33 and 34: J r J A -D n b-n 0 δ n or for the
Page 35 and 36: surface passivation with certain in
Page 37 and 38: ay spectroscopy (EDS), Wavelength d
Page 39 and 40: incidence angle is larger than cert
Page 41 and 42: epresenting those characteristic ph
Page 43 and 44: 1.2.3.3 X-ray Diffraction (XRD) X-r
Page 45 and 46: exhibit diffraction peaks in the no
Page 47 and 48: (nanometers to tens of nanometers),
Page 49 and 50: strongest absorption of microwave s
Page 51 and 52: pinch-off to indicate the lack of a
Page 53: coupling is from unbound ferrite-fe
Page 57 and 58: Fig. 14. A cross sectional scanning
Page 59 and 60: In spite of the same spinel structu
Page 61 and 62: ferrites has been investigated exte
Page 63 and 64: systems is showed in Fig.18.[83] As
Page 65 and 66: precursor vaporization process, e.g
Page 67 and 68: CHAPTER 3. PLASMA ENHANCED ATOMIC L
Page 69 and 70: the initial surface chemistry for t
Page 71 and 72: delay time of 2 seconds between spe
Page 73 and 74: Kcal/mol respectively. The stronger
Page 75 and 76: negative slope) behavior in the pum
Page 77 and 78: the existence of both physisorbed a
Page 79 and 80: decomposition products (Hf-H) and g
Page 81 and 82: dried by ultra high purity N2 gas.
Page 83 and 84: pressure for XPS analysis is around
Page 85 and 86: Hf and N elements, incorporation of
Page 87 and 88: [150,151] This is a unique feature
Page 89 and 90: software. The thickness results are
Page 91 and 92: CHAPTER 4. DIRECT LIQUID INJECTION
Page 93 and 94: film growth region. The properties
Page 95 and 96: solution was accurately controlled
Page 97 and 98: size). For the rocking curve analys
Page 99 and 100: oxygen does not participate in the
Page 101 and 102: ecause vapor velocity cannot be cha
Page 103 and 104: Fig. 40. Cross-sectional view by fi
Page 105 and 106:
the MgAl2O4 substrate confirms cube
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pattern. Fig.44(b) has diffraction
Page 109 and 110:
We have used an AGM (Alternating Gr
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as derived equations for different
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deposited at 600˚C is the lowest.
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wave states degenerate with the FMR
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Fig. 53. ϕ-scan of nickel ferrite
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Surface roughness characterized by
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Fig. 56. X-ray diffraction θ-2θ c
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4.4 Conclusion In summary, we have
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CHAPTER 5. DIRECT LIQUID INJECTION
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eaction zone of the tube furnace is
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Fig. 58. X-ray diffraction characte
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interface. This phenomenon probably
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6.1 Conclusion CHAPTER 6. CONCLUSIO
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the temperature range of 600˚C to
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such as PMN-PT and PZN-PT. CVD proc
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[18]. L. S.-J. Peng, X. X. Xi, B. H
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[54]. B. O. Johansson, J. -E. Sundg
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[96]. J. D. Adam, S. V. Krishnaswam
Page 145 and 146:
[136]. J. Zhao, V. Fuflyigin, F. Wa
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APPENDIX A: LabVIEW PROGRAM FOR PEA
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APPENDIX B: TDMAH MOLECULAR STRUCTU
Page 151 and 152:
H 18 B19 2 A18 1 D17 H 18 B20 2 A19
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