Unconventional Nanopatterning Techniques and Applications

PREFACE xv

I NANOPATTERNING TECHNIQUES 1

1 INTRODUCTION 3

2 MATERIALS 7

2.1 Introduction 7

2.2 Mold Materials and Mold Preparation 8

2.2.1 Soft Molds 8

2.2.2 Hard Molds 19

2.2.3 Rigiflex Molds 19

2.3 Surface Treatment and Modification 21

References 23

3 PATTERNING BASED ON NATURAL FORCE 27

3.1 Introduction 27

3.2 Capillary Force 28

3.2.1 Open-Ended Capillary 29

3.2.2 Closed Permeable Capillary 31

3.2.3 Completely Closed Capillary 40

3.2.4 Fast Patterning 43

3.2.5 Capillary Kinetics 45

3.3 London Force and Liquid Filament Stability 48

3.3.1 Patterning by Selective Dewetting 49

3.3.2 Liquid Filament Stability: Filling and Patterning 51

3.4 Mechanical Stress: Patterning of A Metal Surface 56

References 63

4 PATTERNING BASED ON WORK OF ADHESION 67

4.1 Introduction 67

4.2 Work of Adhesion 68

4.3 Kinetic Effects 71

4.4 Transfer Patterning 74

4.5 Subtractive Transfer Patterning 79

4.6 Transfer Printing 82

References 91

5 PATTERNING BASED ON LIGHT: OPTICAL SOFT LITHOGRAPHY 95

5.1 Introduction 95

5.2 System Elements 96

5.2.1 Overview 96

5.2.2 Elastomeric Photomasks 96

5.2.3 Photosensitive Materials 99

5.3 Two-Dimensional Optical Soft Lithography (OSL) 100

5.3.1 Two-Dimensional OSL with Phase Masks 100

5.3.2 Two-Dimensional OSL with Embossed Masks 104

5.3.3 Two-Dimensional OSL with Amplitude Masks 105

5.3.4 Two-Dimensional OSL with AmplitudePhase Masks 109

5.4 Three-Dimensional Optical Soft Lithography 110

5.4.1 Optics 111

5.4.2 Patterning Results 112

5.5 Applications 117

5.5.1 Low-Voltage Organic Electronics 117

5.5.2 Filters and Mixers for Microfluidics 118

5.5.3 High Energy Fusion Targets and Media for Chemical Release 118

5.5.4 Photonic Bandgap Materials 120

References 122

6 PATTERNING BASED ON EXTERNAL FORCE: NANOIMPRINT LITHOGRAPHY 129
L. Jay Guo

6.1 Introduction 129

6.2 NIL MOLD 133

6.2.1 Mold Fabrication 133

6.2.2 Mold Surface Preparation 137

6.2.3 Flexible Fluoropolymer Mold 137

6.3 NIL Resist 138

6.3.1 Thermoplastic Resist 139

6.3.2 Copolymer Thermoplastic Resists 141

6.3.3 Thermal-Curable Resists 142

6.3.4 UV-Curable Resist 146

6.3.5 Other Imprintable Materials 148

6.4 The Nanoimprint Process 149

6.4.1 Cavity Fill Process 149

6.5 Variations of NIL Processes 152

6.5.1 Reverse Nanoimprint 152

6.5.2 Combined Nanoimprint and Photolithography 155

6.5.3 Roll-to-Roll Nanoimprint Lithography (R2RNIL) 156

6.6 Conclusion 159

References 160

7 PATTERNING BASED ON EDGE EFFECTS: EDGE LITHOGRAPHY 167
Matthias Geissler, Joseph M. McLellan, Eric P. Lee and Younan Xia

7.1 Introduction 167

7.2 Topography-Directed Pattern Transfer 169

7.2.1 Photolithography with Phase-Shifting Masks 170

7.2.2 Use of Edge-Defined Defects in SAMs 172

7.2.3 Controlled Undercutting 175

7.2.4 Edge-Spreading Lithography 176

7.2.5 Edge Transfer Lithography 178

7.2.6 Step-Edge Decoration 180

7.3 Exposure of Nanoscale Edges 181

7.3.1 Fracturing of Thin Films 182

7.3.2 Sectioning of Encapsulated Thin Films 182

7.3.3 Thin Metallic Films along Sidewalls of Patterned Stamps 184

7.3.4 Topographic Reorientation 186

7.4 Conclusion and Outlook 187

References 188

8 PATTERNING WITH ELECTROLYTE: SOLID-STATE SUPERIONIC STAMPING 195
Keng H. Hsu, Peter L. Schultz, Nicholas X. Fang, and Placid M. Ferreira

8.1 Introduction 195

8.2 Solid-State Superionic Stamping 197

8.3 Process Technology 199

8.4 Process Capabilities 203

8.5 Examples of Electrochemically Imprinted Nanostructures Using the S4 Process 208

Acknowledgments 211

References 211

9 PATTERNING WITH GELS: LATTICE-GAS MODELS 215
Paul J. Wesson and Bartosz A. Grzybowski

9.1 Introduction 215

9.2 The RDF Method 218

9.3 Microlenses: Fabrication 218

9.4 Microlenses: Modeling Aspects 220

9.4.1 Modeling Using PDEs 220

9.4.2 Modeling Using Lattice-Gas Method 221

9.5 RDF at the Nanoscale 222

9.5.1 Nanoscopic Features from Counter-Propagating RD Fronts 222

9.5.2 Failure of Continuum Description 225

9.5.3 Lattice-Gas Models at the Nanoscale 227

9.6 Summary and Outlook 229

References 230

10 PATTERNING WITH BLOCK COPOLYMERS 233
Jia-Yu Wang, Wei Chen, and Thomas P. Russell

10.1 Introduction 233

10.2 Orientation 235

10.2.1 Self-Assembling 235

10.2.2 Self-Directing 247

10.3 Long-Range 254

10.3.1 Solvent Annealing 254

10.3.2 Graphoepitaxy 256

10.3.3 Sequential, Orthogonal Fields 260

10.4 Nanoporous BCP Films 262

10.4.1 Ozonolysis 264

10.4.2 Thermal Degradation 264

10.4.3 UV Degradation 267

10.4.4 Selective Extraction 271

10.4.5 “Soft” Chemical Etch 272

10.4.6 Cleavable Junction 272

10.4.7 Solvent-Induced Film Reconstruction 274

References 276

11 PERSPECTIVE ON APPLICATIONS 291

II APPLICATIONS 293

12 SOFT LITHOGRAPHY FOR MICROFLUIDIC MICROELECTROMECHANICAL SYSTEMS (MEMS)
AND OPTICAL DEVICES 295
Svetlana M. Mitrovski, Shraddha Avasthy, Evan M. Erickson, Matthew E. Stewart, John A. Rogers, and Ralph G. Nuzzo

12.1 Introduction 295

12.2 Microfluidic Devices for Concentration Gradients 297

12.3 Electrochemistry and Microfluidics 300

12.4 PDMS and Electrochemistry 302

12.5 Optics and Microfluidics 306

12.6 Unconventional Soft Lithographic Fabrication of Optical Sensors 314

Acknowledgments 317

References 318

13 UNCONVENTIONAL PATTERNING METHODS FOR BIONEMS 325
Pilnam Kim, Yanan Du, Ali Khademhosseini, Robert Langer, and Kahp Y. Suh

13.1 Introduction 325

13.2 Fabrication of Nanofluidic System for Biological Applications 326

13.2.1 Unconventional Methods for Fabrication of Nanochannel 326

13.2.2 Application of Nanofluidic System 332

13.3 Fabrication of Biomolecular Nanoarrays for Biological Applications 338

13.3.1 DNA Nanoarray 338

13.3.2 Protein Arrays 340

13.3.3 Lipid Array 345

13.4 Fabrication of Nanoscale Topographies for Tissue Engineering Applications 347

13.4.1 Nanotopography-Induced Changes in Cell Adhesion 347

13.4.2 Nanotopography-Induced Changes in Cell Morphology 348

References 349

14 MICRO TOTAL ANALYSIS SYSTEM 359
Yuki Tanaka and Takehiko Kitamori

14.1 Introduction 359

14.1.1 Historical Backgrounds 359

14.2 Fundamentals on Microchip Chemistry 361

14.2.1 Characteristics of Liquid Microspace 361

14.2.2 Liquid Handling 362

14.2.3 Concepts of Micro Unit Operation and Continuous-Flow Chemical Processing 362

14.3 Key Technologies 365

14.3.1 Fabrication of Microchips 365

14.3.2 Patterning for Fluid Control 366

14.3.3 Detection 366

14.4 Applications 368

14.4.1 Synthesis 368

14.4.2 Cell Adhesion Control 369

14.4.3 Liquid Handling: Valve Using Wettability 370

References 372

15 COMBINATIONS OF TOP-DOWN AND BOTTOM-UP NANOFABRICATION TECHNIQUES AND THEIR APPLICATION TO CREATE FUNCTIONAL DEVICES 379
Pascale Maury, David N. Reinhoudt, and Jurriaan Huskens

15.1 Introduction 379

15.2 Top-Down and Bottom-Up Techniques 380

15.2.1 Top-Down Techniques 380

15.2.2 Bottom-Up Techniques 383

15.2.3 Mixed Techniques 384

15.3 Combining Top-Down and Bottom-Up Techniques for High Resolution Patterning 385

15.3.1 Top-Down Nanofabrication and Polymerization 386

15.3.2 Top-Down Nanofabrication and Micelles 387

15.3.3 Top-Down Nanofabrication and Block Copolymer Assembly 387

15.3.4 Top-Down Nanofabrication and NP Assembly 389

15.3.5 Top-Down Nanofabrication and Layer-by-Layer Assembly 392

15.4 Applicaion of Combined Top-Down and Bottom-Up Nanofabrication for Creating Functional Devices 397

15.4.1 Photonic Crystal Devices 397

15.4.2 Protein Assays 400

References 406

16 ORGANIC ELECTRONIC DEVICES 419

16.1 Introduction 419

16.2 Organic Light-Emitting Diodes 420

16.3 Organic Thin Film Transistors 429

References 439

17 INORGANIC ELECTRONIC DEVICES 445

17.1 Introduction 445

17.2 Inorganic Semiconductor Materials for Flexible Electronics 446

17.2.1 “Bottom-Up” Approaches 447

17.2.2 “Top-Down” Approaches 449

17.3 Soft Lithography Techniques for Generating Inorganic Electronic Systems 452

17.3.1 Micromolding in Capillaries 453

17.3.2 Imprint Lithography 454

17.3.3 Dry Transfer Printing 454

17.4 Fabrication of Electronic Devices 459

17.4.1 Transistors on Rigid Substrates via MIMIC Processing 459

17.4.2 Flexible Inorganic Transistors 459

17.4.3 Flexible Integrated Circuits 463

17.4.4 Heterogeneous Electronics 466

17.4.5 Stretchable Electronics 469

References 475

18 MECHANICS OF STRETCHABLE SILICON FILMS ON ELASTOMERIC SUBSTRATES 483
Hanqing Jiang, Jizhou Song, Yonggang Huang, and John A. Rogers

18.1 Introduction 483

18.2 Buckling Analysis of Stiff Thin Ribbons on Compliant Substrates 484

18.3 Finite-Deformation Buckling Analysis of Stiff Thin Ribbons on Compliant Substrates 488

18.4 Edge Effects 495

18.5 Effect of Ribbon Width and Spacing 498

18.6 Buckling Analysis of Stiff Thin Membranes on Compliant Substrates 502

18.6.1 One-Dimensional Buckling Mode 504

18.6.2 Checkerboard Buckling Mode 506

18.6.3 Herrington Buckling Mode 506

18.7 Precisely Controlled Buckling of Stiff Thin Ribbons on Compliant Substrates 507

18.8 Concluding Remarks 512

Acknowledgments 512

References 512

19 MULTISCALE FABRICATION OF PLASMONIC STRUCTURES 515
Joel Henzie, Min H. Lee, and Teri W. Odom

19.1 Introduction 515

19.1.1 Brief Primer on Surface Plasmons 517

19.1.2 Conventional Methods to Plasmonic Structures 518

19.2 Soft Lithography and Metal Nanostructures 518

19.3 A Platform for Multiscale Patterning 520

19.3.1 Soft Interference Lithography: Patterns on a Nanoscale Pitch 520

19.3.2 Phase-Shifting Photolithography: Patterns on a Microscale Pitch 520

19.3.3 PEEL: Transferring Photoresist Patterns to Plasmonic Materials 521

19.4 Subwavelength Arrays of Nanoholes: Plasmonic Materials 522

19.4.1 Infinite Arrays of Nanoholes 523

19.4.2 Finite Arrays (Patches) of Nanoholes 525

19.5 Microscale Arrays of Nanoscale Holes 526

19.6 Plasmonic Particle Arrays 528

19.6.1 Metal and Dielectric Nanoparticles 528

19.6.2 Anisotropic Nanoparticles 531

19.6.3 Pyramidal Nanostructures 531

Acknowledgments 533

References 533

20 A RIGIFLEX MOLD AND ITS APPLICATIONS 539
Se-Jin Choi, Tae-Wan Kim, and Seung-Jun Baek

20.1 Introduction 539

20.2 Modulus-Tunable Rigiflex Mold 540

20.3 Applications of Rigiflex Mold 544

20.3.1 From Nanoimprint to Microcontact Printing 544

20.3.2 Rapid Flash Patterning for Residue-Free Patterning 547

20.3.3 Continuous Rigiflex Imprinting 549

20.3.4 Soft Molding Application 553

20.3.5 Capillary Force Lithography Applications 556

20.3.6 Transfer Fabrication Technique 558

References 561

21 NANOIMPRINT TECHNOLOGY FOR FUTURE LIQUID CRYSTAL DISPLAY 565
Jong M. Kim, Hwan Y. Choi, Moon-G. Lee, Seungho Nam, Jin H. Kim, Seongmo Whang, Soo M. Lee, Byoung H. Cheong, Hyuk Kim, Ji M. Lee, and In T. Han

21.1 Introduction 565

21.2 Holographic LGP 569

21.2.1 Design and Properties of Holographic LGP 570

21.2.2 NI Technology for the Holographic LGP 572

21.3 Polarized LGP 573

21.3.1 Design and Properties of Polarized LGP 574

21.3.2 Fabrication of the Polarized LGP 575

21.3.3 Optical Performance of the Polarized LGP 576

21.4 Reflective Polarizer: Wire Grid Polarizer 579

21.4.1 Design and Properies of WGP 580

21.4.2 Fabrication and Applications 581

21.5 Transflective Display 585

21.5.1 Design and Optical Properties of Reflecting Pattern 587

21.5.2 Fabrication of the Reflecting Pattern 588

References 592

INDEX 595