Catalytic Chemical Vapor Deposition

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, JapanKaren 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 xiiiAbbreviations xv1 Introduction 11.1 Thin Film Technologies 11.2 Birth of Cat-CVD 31.3 Research History of Cat-CVD and Related Technologies 41.4 Structure of This Book 7References 82 Fundamentals for Studying the Physics of Cat-CVD and Difference from PECVD 112.1 Fundamental Physics of the Deposition Chamber 112.1.1 Density of Molecules and Their Thermal Velocity 112.1.2 Mean Free Path 132.1.2.1 Equation Expressing the Mean Free Path 132.1.2.2 Estimation of Diameter of Molecules or Species 142.1.2.3 Examples of Mean Free Path 152.1.2.4 Interval Time between the First Collision and the Second Collision 162.1.3 Collisions with a Solid Surface 172.1.3.1 Collisions with a Solid Surface 172.1.3.2 Comparison of Collisions of Molecules in Space with Collisions at Chamber Wall 182.1.4 Residence Time of Species in Chamber 192.2 Difference between Cat-CVD and PECVD Apparatuses 202.3 Fundamental Features of PECVD 212.3.1 Birth of PECVD 212.3.2 Generation of Plasma 222.3.3 DC Plasma to RF Plasma 232.3.4 Sheath Voltage 242.3.5 Density of Decomposed Species in PECVD 252.3.5.1 Number of Collisions between Electrons and Gas Molecules 252.3.5.2 Number of Decomposed Species in PECVD 262.4 Drawbacks of PECVD and Technologies Overcoming Them 282.4.1 Plasma Damage 282.4.2 Increase of Frequency in PECVD 302.4.3 Power Transferring System 312.4.4 Large Area Uniformity for Film Deposition 312.5 Features of Cat-CVD as Technology Overcoming Drawbacks of PECVD 332.A Rough Calculation of Ranges ⟨R⟩ of Si and H Atoms and Defect Range ⟨Rdefect⟩ Created by Si and H Atoms Implanted with Very Low Energy 35References 383 Fundamentals for Analytical Methods for Revealing Chemical Reactions in Cat-CVD 413.1 Importance of Radical Species in CVD Processes 413.2 Radical Detection Techniques 423.3 One-Photon Laser-Induced Fluorescence 433.3.1 General Formulation 433.3.2 Validity of the Assumption of a Two-State System 453.3.3 Anisotropy of the Fluorescence 473.3.4 Correction for Nonradiative Decay Processes 473.3.5 Spectral Broadening 483.3.6 Typical Apparatus for One-Photon LIF and the Experimental Results 493.3.7 Determination of Rotational and Vibrational State Distributions of Molecular Radicals 523.3.8 Estimation of Absolute Densities in One-Photon LIF 533.4 Two-Photon Laser-Induced Fluorescence 553.5 Single-Path Vacuum Ultraviolet (VUV) Laser Absorption 563.6 Other Laser Spectroscopic Techniques 583.6.1 Resonance-Enhanced Multiphoton Ionization 593.6.2 Cavity Ringdown Spectroscopy 603.6.3 Tunable Diode Laser Absorption Spectroscopy 633.7 Mass Spectrometric Techniques 633.7.1 Photoionization Mass Spectrometry 643.7.2 Threshold Ionization Mass Spectrometry 643.7.3 Ion Attachment Mass Spectrometry 663.8 Determination of Gas-Phase Composition of Stable Molecules 663.A Term Symbols Used in Atomic and Molecular Spectroscopy 67References 694 Physics and Chemistry of Cat-CVD 774.1 Kinetics of Molecules in Cat-CVD Chamber 774.1.1 Molecules in Cat-CVD Chamber 774.1.2 Comparison with PECVD for Decomposition 804.1.3 Influence of Surface Area of Catalyzer 814.2 What Happens on Catalyzer Surfaces – Catalytic Reactions 824.3 Poisoning of Surface Decomposition Processes 834.4 Gas Temperature Distribution in Cat-CVD Chambers 854.5 Decomposition Mechanisms on Metal Wire Surfaces and Gas-Phase Kinetics 864.5.1 Catalytic Decomposition of Diatomic Molecules: H2, N2, and O2 864.5.2 Catalytic Decomposition of H2O 894.5.3 Catalytic Decomposition of SiH4 and SiH4/H2 and the Succeeding Gas-Phase Reactions 894.5.4 Catalytic Decomposition of NH3 and the Succeeding Gas-Phase Reactions 904.5.5 Catalytic Decomposition of CH4 and CH4/H2 and the Succeeding Gas-Phase Reactions 914.5.6 Catalytic Decomposition of PH3 and PH3/H2 and the Succeeding Gas-Phase Reactions 924.5.7 Catalytic Decomposition of B2H6 and B2H6/H2 and the Succeeding Gas-Phase Reactions 934.5.8 Catalytic Decomposition of H3NBH3 and Release of B Atoms from Boronized Wires 944.5.9 Catalytic Decomposition of Methyl-Substituted Silanes and Hexamethyldisilazane (HMDS) 944.5.10 Summary of Catalytic Decomposition of Various Molecules on Metal Wires 964.6 Si Film Formation Mechanisms in Cat-CVD 96References 995 Properties of Inorganic Films Prepared by Cat-CVD 1055.1 Properties of Amorphous Silicon (a-Si) Prepared by Cat-CVD 1055.1.1 Fundamentals of Amorphous Silicon (a-Si) 1055.1.1.1 Birth of Device Quality Amorphous Silicon (a-Si) 1055.1.1.2 Band Structure of Amorphous Materials 1065.1.1.3 General Properties of a-Si 1095.1.2 Fundamentals of Preparation of a-Si by Cat-CVD 1155.1.2.1 Deposition Parameters 1155.1.2.2 Structural Studies on Cat-CVD a-Si: Infrared Absorption 1155.1.3 General Properties of Cat-CVD a-Si 1175.1.4 Deposition Mechanism of a-Si in Cat-CVD Process – Growth Model 1255.2 Crystallization of Silicon Films and Microcrystalline Silicon (μc-Si) 1325.2.1 Growth of Crystalline Si Film 1325.2.2 Structure of Cat-CVD Poly-Si 1345.2.3 Properties of Cat-CVD Poly-Si Films 1385.2.4 Si Crystal Growth on Crystalline Si 1415.3 Properties of Silicon Nitride (SiNx) 1435.3.1 Usefulness of Silicon Nitride (SiNx) Films 1435.3.2 Fundamentals for the Preparation of SiNx 1445.3.3 SiNx Preparation from NH3 and SiH4 Mixture 1445.3.4 SiNx Preparation from Mixture of NH3, SiH4, and a Large Amount of H2 1505.3.5 Conformal Step Coverage of SiNx Prepared from the Mixture of NH3, SiH4, and a Large Amount of H2 1535.3.6 Cat-CVD SiNx Prepared from HMDS 1555.4 Properties of Silicon Oxynitride (SiOxNy) 1575.4.1 SiOxNy Films Prepared by SiH4, NH3, H2, andO2 Mixtures 1575.4.2 SiOxNy Films Prepared by HMDS, NH3, H2, andO2 Mixtures 1615.5 Properties of Silicon Oxide (SiO2) Films Prepared by Cat-CVD 1645.6 Preparation of Aluminum Oxide (Al2O3) Films by Cat-CVD 1665.7 Preparation of Aluminum Nitride (AlN) by Cat-CVD 1685.8 Summary of Cat-CVD Inorganic Films 170References 1716 Organic Polymer Synthesis by Cat-CVD-Related Technology – Initiated CVD (iCVD) 1796.1 Introduction 1796.2 PTFE Synthesis by Cat-CVD-Related Technology 1816.2.1 Select Characteristics and Applications of CVD PTFE Films 1826.2.2 Influence of the Catalyzing Materials for PTFE Deposition 1866.3 Mechanistic Principles of iCVD 1876.3.1 Initiators and Inhibitors 1886.3.2 Monomer Adsorption 1896.3.3 Deposition Rate and Molecular Weight 1916.3.4 Copolymerization 1916.3.5 Conformality 1936.4 Functional, Surface-Reactive, and Responsive Organic Films Prepared by iCVD 1946.4.1 Polyglycidyl Methacrylate (PGMA): Properties and Applications 2036.4.2 iCVD Films with Perfluoroalkyl Functional Groups: Properties and Applications 2056.4.3 Polyhydroxyethylacrylate (PHEMA) and Its Copolymers: Properties and Applications 2086.4.4 Organosilicon and Organosilazanes: Properties and Applications 2126.4.5 iCVD of Styrene, 4-Aminostyrene, and Divinylbenzene: Properties and Applications 2176.4.6 iCVD of EGDA and EGDMA: Properties and Applications 2196.4.7 Zwitterionic and Polyionic iCVD Films: Properties and Applications 2216.4.8 iCVD “Smart Surfaces”: Properties and Applications 2226.5 Interfacial Engineering with iCVD: Adhesion and Grafting 2276.6 Reactors for Synthesizing Organic Films by iCVD 2306.7 Summary and Future Prospects for iCVD 232References 2357 Physics and Technologies for Operating Cat-CVD Apparatus 2497.1 Influence of Gas Flow in Cat-CVD Apparatus 2497.1.1 Experiment Using a Long Cylindrical Chamber for Establishing Quasi-laminar Flow 2497.1.2 Dissociation Probability of SiH4 Derived from a Cylindrical Chamber 2517.2 Factors Deciding Film Uniformity 2537.2.1 Equation Expressing the Geometrical Relation between Catalyzer and Substrates 2537.2.2 Example of Estimation of Uniformity of Film Thickness 2547.3 Limit of Packing Density of Catalyzing Wires 2557.4 Thermal Radiation from a Heated Catalyzer 2567.4.1 Fundamentals of Thermal Radiation 2567.4.2 Control of Substrate Temperatures in Thermal Radiation 2577.4.3 Thermal Radiation in CVD Systems 2607.5 Contamination from a Heated Catalyzer 2617.5.1 Contamination of Catalyzing Materials 2617.5.2 Contamination from Other Impurities 2627.5.3 Flux Density of Impurities Emitted from Heated Catalyzers 2657.6 Lifetime of Catalyzing Wires and Techniques to Expand Their Lifetimes 2667.6.1 Introduction 2667.6.2 Silicide Formation of W Catalyzer 2667.6.3 Silicide Formation of Ta Catalyzer 2737.6.4 Suppression of Silicide Formation by Carburization of W Surface 2747.6.5 Ta Catalyzer and Method for Extension of Its Lifetime 2757.6.6 Lifetime Extension by Using TaC 2767.6.7 Lifetime Extension by Using Other Ta Alloys 2777.6.8 Lifetimes of W Catalyzer in Carbon-Containing Gases 2787.6.9 Long-Life Catalyzer Used in iCVD 2807.7 Chamber Cleaning 2817.8 Status of Mass Production Machine 2837.8.1 Cat-CVD Mass Production Machine for Applications in Compound Semiconductors 2837.8.2 Cat-CVD Mass Production Apparatus for Large Area Deposition 2847.8.3 Cat-CVD Apparatus for Coating of PET Bottles 2877.8.4 Prototypes for Any Other Mass Production Machine 288References 2898 Application of Cat-CVD Technologies 2938.1 Introduction: Summarized History of Cat-CVD Research and Application 2938.2 Application to Solar Cells 2958.2.1 Silicon and Silicon Alloy Thin Film Solar Cells 2958.2.1.1 Introduction 2958.2.1.2 Amorphous Silicon Solar Cells 2968.2.1.3 Amorphous Silicon–Germanium Alloy Solar Cells 2978.2.1.4 Microcrystalline Silicon Solar Cells and Tandem Cells 3028.2.1.5 Nanostructured Solar Cells 3048.2.2 Application to Crystalline Silicon (c-Si) Solar Cells 3068.2.2.1 Introduction 3068.2.2.2 Cat-CVD Silicon–Nitride (SiNx)/Amorphous–Silicon (a-Si)-Stacked Passivation 3078.2.2.3 Cat-CVD SiNx/a-Si-Stacked Passivation on Textured c-Si Substrates 3108.2.3 a-Si and c-Si Heterojunction Solar Cells 3128.2.3.1 Introduction 3128.2.3.2 Surface Passivation on c-Si Solar Cells 3128.3 Application to Thin Film Transistors (TFT) 3148.3.1 Amorphous Silicon (a-Si) TFT 3148.3.1.1 General Features of a-Si TFT 3148.3.1.2 Cat-CVD a-Si TFT: Differences from PECVD a-Si TFT 3168.3.2 Poly-Si TFT 3198.4 Surface Passivation on Compound Semiconductor Devices 3208.4.1 Passivation for Gallium–Arsenide (GaAs) High Electron Mobility Transistor (HEMT) 3208.4.2 Passivation for Ultrahigh-Frequency Transistors 3228.4.3 Passivation for Semiconductor Lasers 3228.5 Application for ULSI Industry 3238.6 Gas Barrier Films for Various Devices Such as Organic Devices 3258.6.1 Inorganic Gas Barrier Films, SiNx/SiOxNy, for OLED 3258.6.2 Inorganic/Organic Stacked Gas Barrier Films 3288.6.3 Gas Barrier Films for Food Packages 3328.7 Other Application and Summary of Present Cat-CVD Application 335References 3369 Radicals Generated in Cat-CVD Apparatus and Their Application 3439.1 Generation of High-Density Hydrogen (H) Atoms 3439.1.1 Generation of High-Density H Atoms 3439.1.2 Transportation of H Atoms 3469.2 Cleaning and Etching by H Atoms Generated in Cat-CVD Apparatus 3489.2.1 Etching of Crystalline Silicon 3489.2.2 Cleaning of Carbon-Contaminated Surface 3509.3 Photoresist Removal by Hydrogen Atoms 3519.4 Reduction of Metal Oxide by H atoms 3569.4.1 Reduction of Various Metal Oxides 3569.4.2 Characteristic Control of Metal Oxide Semiconductors by H Atoms 3579.5 Low-Temperature Formation of Low-Resistivity Metal Lines from Liquid Ink by H Atoms 3589.6 Low-Temperature Surface Oxidation – “Cat-Oxidation” 3609.7 Low-Temperature Surface Nitridation – “Cat-Nitridation” of Si and GaAs 3659.8 “Cat-Chemical Sputtering”: A New Thin Film Deposition Method Utilizing Radicals 372References 37410 Cat-doping: A Novel Low-Temperature Impurity Doping Technology 37710.1 Introduction 37710.2 Discovery or Invention of Cat-doping 37810.3 Low-Temperature and Shallow Phosphorus (P) Doping into c-Si 38010.3.1 Measurement of Electrical Properties of a Shallow-Doped Layer 38010.3.2 Measurement of Concentration Profiles of Cat-Doped Impurities by SIMS 38310.3.3 Estimation of Diffusion Constant 38810.3.4 Properties of Cat-Doped P Atoms 38910.3.5 Mechanism of Cat-doping 39210.3.5.1 Possibility of Diffusion Enhancement by H Atoms 39210.3.5.2 Vacancy Transportation Model 39410.3.5.3 Si-Modified Surface Layer Model 39710.4 Low-Temperature Boron (B) Doping into c-Si 39810.5 Cat-Doping into a-Si 40110.6 Feasibility of Cat-Doping for Various Applications 40310.6.1 Surface Potential Control by Cat-doping Realizing High-Quality Passivation 40310.6.2 Cat-doping into a-Si and Its Application to Heterojunction Solar Cells 405References 407Index 411