Laser Precision Microfabrication (eBook)

Koji Sugioka is a senior research scientist in RIKEN and a guest professor of Tokyo University of Science and Tokyo Denki University. Since he joined RIKEN in 1986, he has worked on laser microprocessing of various materials. His current interests center on the development of advanced laser microprocessing techniques performing surface and 3-D microstructuring of transparent materials, with applications to biophotonic microchip devices. He received several awards for his research and inventions in the area of laser microprocessing. He published over 110 articles in international journals and over 70 papers in priceedings, gave more than 60 invited talks at international conferences and more than 70 invited talks at domestic conferences, and has more than 20 patents or pending patents. He has served conference chair, co-chair, and committee member in numerous international conferences. He is also editor-in-chief of the Journal of Laser Micro/Nanoengineering (JLMN). Michel Meunier is professor of engineering physics at École Polytechnique de Montréal and holds the Canada Research Chair in Laser micro/nano-engineering of materials. He obtained his PhD from MIT in 1984 for his work on laser induced chemical vapor deposition of thin films. His current interest is in ultrafast laser-materials interaction and application of laser micro/nanoprocessing in microelectronics, optoelectronics, biomedical and nanotechnologies. He received the Synergy Price for the Canadian Government for his outstanding collaboration with a laser processing industry. He published over 250 papers in international journals and proceedings and gave more than 35 invited talks in international conferences. He is one of the editor of the Journal of Laser Micro/Nanoengineering (JLMN). Alberto Piqué is Head of the Electronic and Optical Materials & Devices Section, in the Materials Science Division at the U.S. Naval Research Laboratory (NRL). Since joining the NRL in 1997, he has investigated the use of laser-based direct-write techniques for the rapid prototyping of microelectronics, sensors and micro-power sources. His research interests include the study of processes involving laser-material interactions, in particular those relevant to pulsed laser deposition and laser forward transfer as applied to the fabrication of thin-films, multilayers and embedded structures. He has published over 130 scientific articles, presented over 35 invited talks, co-edited a book in Direct-Write Technologies and holds 15 U.S. patents with 10 more pending in laser materials processing. He is an associate editor of the Journal of Laser Micro/Nanoengineering (JLMN).

Preface 6
Contents 8
Contributors 16
1 Process Control in Laser Material Processingfor the Micro and Nanometer Scale Domains 18
1.1 Introduction 18
1.2 Laser Processing 22
1.2.1 Laser Wavelength 24
1.2.2 Laser Power 28
1.2.3 Laser Dose 30
1.2.4 Laser Beam 33
1.2.5 Laser Pulse Temporal Profile 36
1.2.6 Pattern Generation 40
1.3 Possible Steps Forward 43
1.4 Conclusions 46
References 47
2 Theory and Simulation of Laser Ablation – from Basic Mechanisms to Applications 52
2.1 Introduction 52
2.2 Basic Physics 54
2.2.1 Light-Matter Interaction 54
2.2.2 Material Removal from the Target: The Basics of Ablation 54
2.3 Ablation in the Thermal Regime 55
2.3.1 Thermodynamics 55
2.3.2 Conventional Wisdom: Early Theories 56
2.3.3 A New Understanding 58
2.3.4 Computer Models 58
2.3.5 The Femtosecond Regime 61
2.3.5.1 Visual Analysis 61
2.3.5.2 Thermodynamic Trajectories 63
2.3.5.3 Ablation Mechanisms vs Depth 65
2.3.6 Picosecond Pulses and Beyond 66
2.3.7 Molecular Solids 67
2.4 Materials Processing 70
2.4.1 Nanoparticle Production in Solvents 70
2.4.2 Damages and Heat Affected Zones 72
2.5 Conclusions and Perspectives 75
References 76
3 Laser Devices and Optical Systems for Laser Precision Microfabrication 79
3.1 Introduction 79
3.2 Laser Devices 80
3.2.1 Various Laser Devices from Deep UV and Mid-IR Spectral Region 80
3.2.1.1 Excimer Lasers 80
3.2.1.2 Solid-State Lasers 81
3.2.1.3 CO2 Lasers 82
3.2.2 Diode-Pumped High-Brightness Continuous Wave Solid-State Lasers 83
3.2.2.1 Diode-Pumped Neodymium-Doped Solid-State Lasers 83
3.2.2.2 Diode-Pumped Ytterbium-Doped Solid-State Lasers and Fiber Lasers 84
3.2.3 Q-Switching and Cavity Dumping 86
3.2.3.1 Acousto-Optic Q-Switching 86
3.2.3.2 Electro-Optic Q-Switching and Pulse Slicing 87
3.2.3.3 Cavity Dumping 87
3.2.4 Picosecond and Femtosecond, Ultrafast Pulsed Laser Oscillators and Amplifiers 88
3.2.4.1 Mode Locking 88
3.2.4.2 Ultrafast Ti:Sapphire Laser Systems 89
3.2.4.3 Rare-Earth-Doped and Diode-Pumped Ultrafast Laser Systems 90
3.3 Optical Systems 93
3.3.1 Optical Components for Modification and Control of Laser Beams 93
3.3.1.1 Optics for Generating Radially-Polarized and Azimuthally-Polarized Laser Beams 93
3.3.2 Optical Systems for Beam Shape Transformation 94
3.3.2.1 Beam Homogenizers for Mask Imaging Systems 94
3.3.2.2 Gaussian to Flat-Top Beam Shaping for Laser Microfabrication 95
3.3.2.3 Anamorphic Beam Transformation System for a Very Thin and Long Line 95
3.3.2.4 Beam Shaping for Parallel Material Processing 96
3.3.2.5 Beam Shaping to Generate Nondiffractive Bessel Beams 97
3.3.3 Galvanometer-Based Optical Scanners 97
3.3.3.1 Basics of Galvanometer-Based Optical Scanners 97
3.3.4 Spatial Light Modulators 98
3.3.4.1 Laser Pattern Generator with a MEMS-Based Spatial Light Modulator 98
3.3.4.2 Parallel Processing Using Liquid-Crystal Spatial Light Modulators 98
3.3.5 Nonlinear-Optical Systems for Harmonic Generation 99
3.3.5.1 Second Harmonic Generation 99
3.3.5.2 Third Harmonic Generation 99
3.3.6 Optical Systems for Beam Characterization and Process Monitoring 100
3.3.6.1 Beam Characterization 100
3.3.6.2 Process Monitoring 101
3.4 Summary 102
References 102
4 Fundamentals of Laser-Material Interaction and Application to Multiscale Surface Modification 106
4.1 Introduction 106
4.2 Fundamentals of Laser Surface Processing 107
4.2.1 Light Propagation in Materials 107
4.2.2 Energy Absorption Mechanisms 109
4.2.3 The Heat Equation 111
4.2.4 Material Response 113
4.2.4.1 Thermally Activated Processes 113
4.2.4.2 Surface Melting 113
4.2.4.3 Ablation 114
4.3 Laser Surface Processing Applications 116
4.4 Case Study I: Surface Texturing for EnhancedOptical Properties 119
4.5 Case Study II: Surface Texturing for Enhanced Biological Interactions 125
4.6 Conclusions 131
References 132
5 Temporal Pulse Tailoring in Ultrafast Laser Manufacturing Technologies 136
5.1 Introduction 136
5.2 Fundamental and Technical Aspects of Pulse Shaping 138
5.2.1 Basics of Ultrashort Laser Pulses 138
5.2.2 Frequency Domain Manipulation (Mathematical Formalism) 138
5.2.3 Analytical Phase Functions Relevant to Material Processing 142
5.2.3.1 Polynomial Phase Functions 142
5.2.3.2 Pulse Sequences 143
5.2.3.3 Linear Combinations of the Above Phase Masks 144
5.2.3.4 Iterative Fourier Approaches for Designing Pulse Shapes 144
5.2.3.5 Polarization-Shaped Pulses in the Temporal Domain 144
5.2.4 Pulse Shaping in the Spatial Domain 145
5.2.5 Experimental Implementations for Temporal Pulse Shaping 145
5.2.6 Optimization Strategies 147
5.3 Material Interaction with Temporally Shaped Pulses 148
5.3.1 Control of Laser-Induced Primary Excitation Events 148
5.3.2 Engineered Thermodynamic Phase-Space Trajectories 150
5.3.3 Refractive Index Engineering by Temporally Tailored Pulses 154
5.4 Conclusion and Perspectives 156
References 157
6 Laser Nanosurgery, Manipulation, and Transportationof Cells and Tissues 160
6.1 Introduction 160
6.2 Laser Direct Surgery 161
6.2.1 Nanosurgery with a Focused Laser Beam in the Ultraviolet and Visible Region 161
6.2.2 Femtosecond Laser Surgery 162
6.2.2.1 Chromosome Dissection Using Femtosecond Nanosurgery 162
6.2.2.2 Nanosurgery of Intracellular Organelles 163
6.2.2.3 Femtosecond Laser Nanoaxotomy 165
6.2.2.4 Optoperforation and Transfection 165
6.2.2.5 Nanosurgery of Tissue 167
6.2.2.6 Mechanisms for Femtosecond Laser Surgery 168
6.3 Nanoparticles and Chromophore-Assisted Manipulation and Processing 168
6.3.1 Chromophore-Assisted Laser Inactivation 168
6.3.2 Plasmonic Nanosurgery 169
6.4 Laser Manipulation and Transport of Cells and Tissues 169
6.4.1 Optical Tweezers 169
6.4.2 Laser Transport of Cells 170
6.5 Application of Laser-Induced ShockWavesand Mechanical Waves 170
6.5.1 Targeted Gene Transfection by Laser-Induced Mechanical Waves 170
6.5.2 Femtosecond Laser-Induced ShockWave in Liquid 171
6.5.2.1 Femtosecond Laser-Induced Crystallization of Proteinsand Molecules 171
6.5.2.2 Patterning of Protein Cubes and Cells by Femtosecond Laser Induced Impulsive Force 171
6.5.2.3 Femtosecond Laser-Induced Injection of Nanoparticles into Cell 172
6.6 Laser-Induced Stimulation 172
6.7 Fabrication of Microfluidic Channels and Scaffolds 173
6.8 Summary and Conclusions 174
References 174
7 Laser Synthesis of Nanomaterials 177
7.1 Introduction 177
7.2 General Principles of Laser Based Synthesis of Nanomaterials 178
7.2.1 Nanosecond Pulsed Laser Ablation 179
7.2.2 Ultrafast Laser Ablation 180
7.3 Synthesis of Nanomaterials Based on Laser Ablation of a Bulk Target 182
7.4 Laser Ablation in Vacuum/Gas Environment 185
7.5 Laser Ablation in Liquids: Formation of ColloidalNanoparticles 187
7.5.1 Ablation Mechanisms 187
7.5.2 Effect of Laser Parameters 190
7.5.3 Effect of Stabilizing Agents 191
7.5.4 Process Model 193
7.6 Synthesis of Nanomaterials Based on Laser Interaction with Micro/Nanomaterials 194
7.7 Conclusions and Perspective 196
References 197
8 Ultrafast Laser Micro- and Nanostructuring 202
8.1 Introduction 203
8.2 Theoretical Background 203
8.2.1 Dielectrics 204
8.2.2 Metals 207
8.2.3 Thermodynamic Approach 208
8.3 Recent Results 211
8.3.1 Top-Down Approaches to Nanostructures 211
8.3.2 Thin Film Ablation 212
8.3.3 Incubation Phenomena 214
8.3.4 Bottom-Up Approaches to Nanostructures 216
8.3.5 Biogenetic Materials 217
8.4 Outlook 219
8.4.1 Recent Instrumental Developments 219
8.4.2 Nanostructuring in the Nearfield 221
8.5 Summary 222
References 222
9 3D Fabrication of Embedded Microcomponents 227
9.1 Introduction 227
9.2 Principles of Internal Processing 228
9.3 Refractive Index Modification 229
9.3.1 Advantages of Femtosecond Laser in Photonic Device Fabrication 229
9.3.2 Optical Waveguide Writing 230
9.3.3 Fabrication of Photonic Devices 232
9.3.4 Fabrication of Fiber Bragg Gratings (FBGs) 235
9.4 Formation of 3D Hollow Microstructures 237
9.4.1 Direct Ablation in Water 237
9.4.2 Internal Modification Followed by Wet Etching 238
9.5 3D Integration of Microcomponents 240
9.6 Beam Shaping for Fabrication of 3D Microcomponents 243
9.7 Summary 245
References 246
10 Micromachining and Patterning 251
10.1 Introduction 251
10.2 Direct Writing 252
10.3 Micro Fluidics 253
10.4 Gratings 255
10.5 Diffractive Optical Elements 257
10.6 Micro Lenses/Lens Arrays 258
10.7 Patterning of Layers 261
10.8 Dielectric Masks 264
10.9 Two Step Processing of Layers: Ablation + Oxidation 265
10.10 Summary and Outlook 267
References 268
11 Laser Transfer Techniques for Digital Microfabrication 270
11.1 Introduction 270
11.2 Lasers in Digital Microfabrication 272
11.3 Origins of Laser Forward Transfer 273
11.3.1 Early Work in Laser-Induced Forward Transfer 273
11.3.2 Transferring Metals and Other Materials with LIFT 275
11.3.3 Fundamental Limitations of the Basic LIFT Approach 276
11.4 Evolution of Laser Forward Transfer Techniques 276
11.4.1 The Role of the Donor Substrate 277
11.4.2 Development of Multilayered Ribbons and Dynamic Release Layers 278
11.4.3 LIFT with Ultra-Short Laser Pulses 280
11.4.4 Laser Transfer of Compositeor Matrix-Based Materials 281
11.4.5 Laser Transfer of Rheological Systems 282
11.4.6 Jetting Effects 284
11.4.7 Laser Transfer of Entire Devices 285
11.4.8 Recent Variations of the Basic LIFT Process 287
11.5 Applications 288
11.5.1 Microelectronics 288
11.5.2 Sensor and Micropower Generation Devices 289
11.5.3 Biomaterials 292
11.5.4 Embedded Electronic Circuits 294
11.6 The Future of Laser-Based Digital Microfabrication 295
11.6.1 Laser Forward Transfer vs. Other Digital Microfabrication Processes 296
11.7 Summary 297
References 298
12 Hybrid Laser Processing of Transparent Materials 303
12.1 Introduction 303
12.2 Multiwavelength Excitation Process 304
12.2.1 Principle of Multiwavelength Excitation Process 304
12.2.2 Microfabrication of Transparent Materialsby Multiwavelength Excitation Process 305
12.3 Media Assisted Process 307
12.3.1 Classification of Media Assisted Processes 307
12.3.2 LIPAA Process 309
12.3.3 LIBWE Process 312
12.4 Conclusions 316
References 317
13 Drilling, Cutting, Welding, Marking and Microforming 321
13.1 Parameter Regimes 321
13.1.1 Pulse Duration 322
13.1.1.1 Continuous Wave and Long Laser Pulses 323
13.1.1.2 Short Laser Pulses 323
13.1.1.3 Ultrashort Laser Pulses 324
13.1.2 Wavelength 324
13.1.3 Beam Quality 325
13.1.4 Output Power 325
13.2 Drilling 326
13.2.1 Laser Drilling Without Relative Movement Between Laser Spot and Workpiece 326
13.2.1.1 Single Pulse Drilling 327
13.2.1.2 Percussion Drilling 328
13.2.2 Laser Drilling with Relative Movement Between Laser Spot and Workpiece 328
13.2.2.1 Trepanning 329
13.2.2.2 Helical Drilling 329
13.2.3 Trepanning Head 330
13.2.4 Further Trends and Outlook 330
13.3 Cutting 331
13.3.1 Melt Cutting 331
13.3.2 Laser Ablation Cutting 333
13.3.2.1 Short Pulse Laser Cutting 334
13.3.2.2 Ultra-Short Pulse Laser Cutting 334
13.3.2.3 Process Parameters 334
13.3.3 Laser Scribing 336
13.3.4 Laser Induced Stress Cutting 336
13.4 Microjoining 337
13.4.1 Welding 337
13.4.2 Soldering 340
13.5 Marking 341
13.5.1 Laser Marking by Material Removal or Addition 341
13.5.2 Laser Marking by Material Modification 342
13.6 Microforming 343
13.7 Summary 343
References 344
Index 346