Catalytic Chemical Vapor Deposition Technology and Applications of Cat-CVD

The authoritative reference on catalytic chemical vapor deposition, written by the inventor of the technology.

This comprehensive book covers a wide scope of Cat-CVD and related technologies from the fundamentals to the many applications, including the design of a Cat-CVD apparatus. Featuring contributions from four senior leaders in the field, including the father of catalytic chemical vapor deposition, it also introduces some of the techniques used in the observation of Cat-CVD related phenomena so that readers can understand the concepts of such techniques.

Catalytic Chemical Vapor Deposition: Technology and Applications of Cat-CVD begins by reviewing the analytical tools for elucidating the chemical reactions in Cat-CVD, such as laser-induced fluorescence and deep ultra-violet absorption, and explains in detail the underlying physics and chemistry of the Cat-CVD technology. Subsequently it provides an overview of the synthesis and properties of Cat-CVD-prepared inorganic and organic thin films. The last parts of this unique book are devoted to the design and operation of Cat-CVD apparatuses and the applications.

• Provides coherent coverage of the fundamentals and applications of catalytic chemical vapor deposition (Cat-CVD)
• Assembles in one place the state of the art of this rapidly growing field, allowing new researchers to get an overview that is difficult to obtain solely from journal articles
• Presents comparisons of different Cat-CVD methods which are usually not found in research papers
• Bridges academic and industrial research, showing how CVD can be scaled up from the lab to large-scale industrial utilization in the high-tech industry.

Catalytic Chemical Vapor Deposition: Technology and Applications is an excellent one-stop resource for researchers and engineers working on or entering the field of Cat-CVD, Hot-Wire CVD, iCVD, and related technologies.

Hideki Matsumura, PhD, is Professor Emeritus in the School of Materials Science at the Japan Advanced Institute of Science and Technology (JAIST), Japan. 

Hironobu Umemoto, PhD, is Professor Emeritus of Shizuoka University, Japan

Karen K. Gleason, PhD, is Associate Provost and the Alexander and I. Michael Kasser Professor of Chemical Engineering at MIT, USA. 

Ruud E. I. Schropp, PhD, is Extraordinary Professor at University of Western Cape, South Africa

Preface xiii

Abbreviations xv

1 Introduction 1

1.1 Thin Film Technologies 1

1.2 Birth of Cat-CVD 3

1.3 Research History of Cat-CVD and Related Technologies 4

1.4 Structure of This Book 7

References 8

2 Fundamentals for Studying the Physics of Cat-CVD and Difference from PECVD 11

2.1 Fundamental Physics of the Deposition Chamber 11

2.1.1 Density of Molecules and Their Thermal Velocity 11

2.1.2 Mean Free Path 13

2.1.2.1 Equation Expressing the Mean Free Path 13

2.1.2.2 Estimation of Diameter of Molecules or Species 14

2.1.2.3 Examples of Mean Free Path 15

2.1.2.4 Interval Time between the First Collision and the Second Collision 16

2.1.3 Collisions with a Solid Surface 17

2.1.3.1 Collisions with a Solid Surface 17

2.1.3.2 Comparison of Collisions of Molecules in Space with Collisions at Chamber Wall 18

2.1.4 Residence Time of Species in Chamber 19

2.2 Difference between Cat-CVD and PECVD Apparatuses 20

2.3 Fundamental Features of PECVD 21

2.3.1 Birth of PECVD 21

2.3.2 Generation of Plasma 22

2.3.3 DC Plasma to RF Plasma 23

2.3.4 Sheath Voltage 24

2.3.5 Density of Decomposed Species in PECVD 25

2.3.5.1 Number of Collisions between Electrons and Gas Molecules 25

2.3.5.2 Number of Decomposed Species in PECVD 26

2.4 Drawbacks of PECVD and Technologies Overcoming Them 28

2.4.1 Plasma Damage 28

2.4.2 Increase of Frequency in PECVD 30

2.4.3 Power Transferring System 31

2.4.4 Large Area Uniformity for Film Deposition 31

2.5 Features of Cat-CVD as Technology Overcoming Drawbacks of PECVD 33

2.A Rough Calculation of Ranges ⟨R⟩ of Si and H Atoms and Defect Range ⟨R_defect⟩ Created by Si and H Atoms Implanted with Very Low Energy 35

References 38

3 Fundamentals for Analytical Methods for Revealing Chemical Reactions in Cat-CVD 41

3.1 Importance of Radical Species in CVD Processes 41

3.2 Radical Detection Techniques 42

3.3 One-Photon Laser-Induced Fluorescence 43

3.3.1 General Formulation 43

3.3.2 Validity of the Assumption of a Two-State System 45

3.3.3 Anisotropy of the Fluorescence 47

3.3.4 Correction for Nonradiative Decay Processes 47

3.3.5 Spectral Broadening 48

3.3.6 Typical Apparatus for One-Photon LIF and the Experimental Results 49

3.3.7 Determination of Rotational and Vibrational State Distributions of Molecular Radicals 52

3.3.8 Estimation of Absolute Densities in One-Photon LIF 53

3.4 Two-Photon Laser-Induced Fluorescence 55

3.5 Single-Path Vacuum Ultraviolet (VUV) Laser Absorption 56

3.6 Other Laser Spectroscopic Techniques 58

3.6.1 Resonance-Enhanced Multiphoton Ionization 59

3.6.2 Cavity Ringdown Spectroscopy 60

3.6.3 Tunable Diode Laser Absorption Spectroscopy 63

3.7 Mass Spectrometric Techniques 63

3.7.1 Photoionization Mass Spectrometry 64

3.7.2 Threshold Ionization Mass Spectrometry 64

3.7.3 Ion Attachment Mass Spectrometry 66

3.8 Determination of Gas-Phase Composition of Stable Molecules 66

3.A Term Symbols Used in Atomic and Molecular Spectroscopy 67

References 69

4 Physics and Chemistry of Cat-CVD 77

4.1 Kinetics of Molecules in Cat-CVD Chamber 77

4.1.1 Molecules in Cat-CVD Chamber 77

4.1.2 Comparison with PECVD for Decomposition 80

4.1.3 Influence of Surface Area of Catalyzer 81

4.2 What Happens on Catalyzer Surfaces – Catalytic Reactions 82

4.3 Poisoning of Surface Decomposition Processes 83

4.4 Gas Temperature Distribution in Cat-CVD Chambers 85

4.5 Decomposition Mechanisms on Metal Wire Surfaces and Gas-Phase Kinetics 86

4.5.1 Catalytic Decomposition of Diatomic Molecules: H₂, N₂, and O₂ 86

4.5.2 Catalytic Decomposition of H₂O 89

4.5.3 Catalytic Decomposition of SiH₄ and SiH₄/H₂ and the Succeeding Gas-Phase Reactions 89

4.5.4 Catalytic Decomposition of NH₃ and the Succeeding Gas-Phase Reactions 90

4.5.5 Catalytic Decomposition of CH₄ and CH₄/H₂ and the Succeeding Gas-Phase Reactions 91

4.5.6 Catalytic Decomposition of PH₃ and PH₃/H₂ and the Succeeding Gas-Phase Reactions 92

4.5.7 Catalytic Decomposition of B₂H₆ and B₂H₆/H₂ and the Succeeding Gas-Phase Reactions 93

4.5.8 Catalytic Decomposition of H₃NBH₃ and Release of B Atoms from Boronized Wires 94

4.5.9 Catalytic Decomposition of Methyl-Substituted Silanes and Hexamethyldisilazane (HMDS) 94

4.5.10 Summary of Catalytic Decomposition of Various Molecules on Metal Wires 96

4.6 Si Film Formation Mechanisms in Cat-CVD 96

References 99

5 Properties of Inorganic Films Prepared by Cat-CVD 105

5.1 Properties of Amorphous Silicon (a-Si) Prepared by Cat-CVD 105

5.1.1 Fundamentals of Amorphous Silicon (a-Si) 105

5.1.1.1 Birth of Device Quality Amorphous Silicon (a-Si) 105

5.1.1.2 Band Structure of Amorphous Materials 106

5.1.1.3 General Properties of a-Si 109

5.1.2 Fundamentals of Preparation of a-Si by Cat-CVD 115

5.1.2.1 Deposition Parameters 115

5.1.2.2 Structural Studies on Cat-CVD a-Si: Infrared Absorption 115

5.1.3 General Properties of Cat-CVD a-Si 117

5.1.4 Deposition Mechanism of a-Si in Cat-CVD Process – Growth Model 125

5.2 Crystallization of Silicon Films and Microcrystalline Silicon (μc-Si) 132

5.2.1 Growth of Crystalline Si Film 132

5.2.2 Structure of Cat-CVD Poly-Si 134

5.2.3 Properties of Cat-CVD Poly-Si Films 138

5.2.4 Si Crystal Growth on Crystalline Si 141

5.3 Properties of Silicon Nitride (SiN_x) 143

5.3.1 Usefulness of Silicon Nitride (SiN_x) Films 143

5.3.2 Fundamentals for the Preparation of SiN_x 144

5.3.3 SiN_x Preparation from NH₃ and SiH₄ Mixture 144

5.3.4 SiN_x Preparation from Mixture of NH₃, SiH₄, and a Large Amount of H₂ 150

5.3.5 Conformal Step Coverage of SiNx Prepared from the Mixture of NH₃, SiH₄, and a Large Amount of H₂ 153

5.3.6 Cat-CVD SiN_x Prepared from HMDS 155

5.4 Properties of Silicon Oxynitride (SiO_xN_y) 157

5.4.1 SiO_xN_y Films Prepared by SiH₄, NH₃, H₂, andO₂ Mixtures 157

5.4.2 SiO_xN_y Films Prepared by HMDS, NH₃, H₂, andO₂ Mixtures 161

5.5 Properties of Silicon Oxide (SiO₂) Films Prepared by Cat-CVD 164

5.6 Preparation of Aluminum Oxide (Al₂O₃) Films by Cat-CVD 166

5.7 Preparation of Aluminum Nitride (AlN) by Cat-CVD 168

5.8 Summary of Cat-CVD Inorganic Films 170

References 171

6 Organic Polymer Synthesis by Cat-CVD-Related Technology – Initiated CVD (iCVD) 179

6.1 Introduction 179

6.2 PTFE Synthesis by Cat-CVD-Related Technology 181

6.2.1 Select Characteristics and Applications of CVD PTFE Films 182

6.2.2 Influence of the Catalyzing Materials for PTFE Deposition 186

6.3 Mechanistic Principles of iCVD 187

6.3.1 Initiators and Inhibitors 188

6.3.2 Monomer Adsorption 189

6.3.3 Deposition Rate and Molecular Weight 191

6.3.4 Copolymerization 191

6.3.5 Conformality 193

6.4 Functional, Surface-Reactive, and Responsive Organic Films Prepared by iCVD 194

6.4.1 Polyglycidyl Methacrylate (PGMA): Properties and Applications 203

6.4.2 iCVD Films with Perfluoroalkyl Functional Groups: Properties and Applications 205

6.4.3 Polyhydroxyethylacrylate (PHEMA) and Its Copolymers: Properties and Applications 208

6.4.4 Organosilicon and Organosilazanes: Properties and Applications 212

6.4.5 iCVD of Styrene, 4-Aminostyrene, and Divinylbenzene: Properties and Applications 217

6.4.6 iCVD of EGDA and EGDMA: Properties and Applications 219

6.4.7 Zwitterionic and Polyionic iCVD Films: Properties and Applications 221

6.4.8 iCVD “Smart Surfaces”: Properties and Applications 222

6.5 Interfacial Engineering with iCVD: Adhesion and Grafting 227

6.6 Reactors for Synthesizing Organic Films by iCVD 230

6.7 Summary and Future Prospects for iCVD 232

References 235

7 Physics and Technologies for Operating Cat-CVD Apparatus 249

7.1 Influence of Gas Flow in Cat-CVD Apparatus 249

7.1.1 Experiment Using a Long Cylindrical Chamber for Establishing Quasi-laminar Flow 249

7.1.2 Dissociation Probability of SiH₄ Derived from a Cylindrical Chamber 251

7.2 Factors Deciding Film Uniformity 253

7.2.1 Equation Expressing the Geometrical Relation between Catalyzer and Substrates 253

7.2.2 Example of Estimation of Uniformity of Film Thickness 254

7.3 Limit of Packing Density of Catalyzing Wires 255

7.4 Thermal Radiation from a Heated Catalyzer 256

7.4.1 Fundamentals of Thermal Radiation 256

7.4.2 Control of Substrate Temperatures in Thermal Radiation 257

7.4.3 Thermal Radiation in CVD Systems 260

7.5 Contamination from a Heated Catalyzer 261

7.5.1 Contamination of Catalyzing Materials 261

7.5.2 Contamination from Other Impurities 262

7.5.3 Flux Density of Impurities Emitted from Heated Catalyzers 265

7.6 Lifetime of Catalyzing Wires and Techniques to Expand Their Lifetimes 266

7.6.1 Introduction 266

7.6.2 Silicide Formation of W Catalyzer 266

7.6.3 Silicide Formation of Ta Catalyzer 273

7.6.4 Suppression of Silicide Formation by Carburization of W Surface 274

7.6.5 Ta Catalyzer and Method for Extension of Its Lifetime 275

7.6.6 Lifetime Extension by Using TaC 276

7.6.7 Lifetime Extension by Using Other Ta Alloys 277

7.6.8 Lifetimes of W Catalyzer in Carbon-Containing Gases 278

7.6.9 Long-Life Catalyzer Used in iCVD 280

7.7 Chamber Cleaning 281

7.8 Status of Mass Production Machine 283

7.8.1 Cat-CVD Mass Production Machine for Applications in Compound Semiconductors 283

7.8.2 Cat-CVD Mass Production Apparatus for Large Area Deposition 284

7.8.3 Cat-CVD Apparatus for Coating of PET Bottles 287

7.8.4 Prototypes for Any Other Mass Production Machine 288

References 289

8 Application of Cat-CVD Technologies 293

8.1 Introduction: Summarized History of Cat-CVD Research and Application 293

8.2 Application to Solar Cells 295

8.2.1 Silicon and Silicon Alloy Thin Film Solar Cells 295

8.2.1.1 Introduction 295

8.2.1.2 Amorphous Silicon Solar Cells 296

8.2.1.3 Amorphous Silicon–Germanium Alloy Solar Cells 297

8.2.1.4 Microcrystalline Silicon Solar Cells and Tandem Cells 302

8.2.1.5 Nanostructured Solar Cells 304

8.2.2 Application to Crystalline Silicon (c-Si) Solar Cells 306

8.2.2.1 Introduction 306

8.2.2.2 Cat-CVD Silicon–Nitride (SiN_x)/Amorphous–Silicon (a-Si)-Stacked Passivation 307

8.2.2.3 Cat-CVD SiN_x/a-Si-Stacked Passivation on Textured c-Si Substrates 310

8.2.3 a-Si and c-Si Heterojunction Solar Cells 312

8.2.3.1 Introduction 312

8.2.3.2 Surface Passivation on c-Si Solar Cells 312

8.3 Application to Thin Film Transistors (TFT) 314

8.3.1 Amorphous Silicon (a-Si) TFT 314

8.3.1.1 General Features of a-Si TFT 314

8.3.1.2 Cat-CVD a-Si TFT: Differences from PECVD a-Si TFT 316

8.3.2 Poly-Si TFT 319

8.4 Surface Passivation on Compound Semiconductor Devices 320

8.4.1 Passivation for Gallium–Arsenide (GaAs) High Electron Mobility Transistor (HEMT) 320

8.4.2 Passivation for Ultrahigh-Frequency Transistors 322

8.4.3 Passivation for Semiconductor Lasers 322

8.5 Application for ULSI Industry 323

8.6 Gas Barrier Films for Various Devices Such as Organic Devices 325

8.6.1 Inorganic Gas Barrier Films, SiN_x/SiO_xN_y, for OLED 325

8.6.2 Inorganic/Organic Stacked Gas Barrier Films 328

8.6.3 Gas Barrier Films for Food Packages 332

8.7 Other Application and Summary of Present Cat-CVD Application 335

References 336

9 Radicals Generated in Cat-CVD Apparatus and Their Application 343

9.1 Generation of High-Density Hydrogen (H) Atoms 343

9.1.1 Generation of High-Density H Atoms 343

9.1.2 Transportation of H Atoms 346

9.2 Cleaning and Etching by H Atoms Generated in Cat-CVD Apparatus 348

9.2.1 Etching of Crystalline Silicon 348

9.2.2 Cleaning of Carbon-Contaminated Surface 350

9.3 Photoresist Removal by Hydrogen Atoms 351

9.4 Reduction of Metal Oxide by H atoms 356

9.4.1 Reduction of Various Metal Oxides 356

9.4.2 Characteristic Control of Metal Oxide Semiconductors by H Atoms 357

9.5 Low-Temperature Formation of Low-Resistivity Metal Lines from Liquid Ink by H Atoms 358

9.6 Low-Temperature Surface Oxidation – “Cat-Oxidation” 360

9.7 Low-Temperature Surface Nitridation – “Cat-Nitridation” of Si and GaAs 365

9.8 “Cat-Chemical Sputtering”: A New Thin Film Deposition Method Utilizing Radicals 372

References 374

10 Cat-doping: A Novel Low-Temperature Impurity Doping Technology 377

10.1 Introduction 377

10.2 Discovery or Invention of Cat-doping 378

10.3 Low-Temperature and Shallow Phosphorus (P) Doping into c-Si 380

10.3.1 Measurement of Electrical Properties of a Shallow-Doped Layer 380

10.3.2 Measurement of Concentration Profiles of Cat-Doped Impurities by SIMS 383

10.3.3 Estimation of Diffusion Constant 388

10.3.4 Properties of Cat-Doped P Atoms 389

10.3.5 Mechanism of Cat-doping 392

10.3.5.1 Possibility of Diffusion Enhancement by H Atoms 392

10.3.5.2 Vacancy Transportation Model 394

10.3.5.3 Si-Modified Surface Layer Model 397

10.4 Low-Temperature Boron (B) Doping into c-Si 398

10.5 Cat-Doping into a-Si 401

10.6 Feasibility of Cat-Doping for Various Applications 403

10.6.1 Surface Potential Control by Cat-doping Realizing High-Quality Passivation 403

10.6.2 Cat-doping into a-Si and Its Application to Heterojunction Solar Cells 405

References 407

Index 411

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