This newest edition of Principles of Lithography reflects the continuing advancement of lithographic technology. In recent years, certain topics, such as line-edge roughness (LER), multi-electron-beam writers, and nonlinear overlay models, have become much more significant to practicing lithographers, and more extensive treatments are therefore provided. EUV lithography is on the threshold for use in high-volume manufacturing, at nodes where a number of complex phenomena are relevant, and the chapter on EUV lithography has been expanded accordingly. New references and homework problems have been added. It is expected that the reader of this book will have a foundation in basic physics and chemistry. No topics will require knowledge of mathematics beyond elementary calculus.
Chapter 1 Overview of Lithography Problems Chapter 2 Optical Pattern Formation 2.1 The Problem of Imaging 2.2 Aerial Images 2.3 The Contributions of Physics and Chemistry 2.4 Focus Problems References Chapter 3 Photoresists 3.1 Positive and Negative Resists 3.2 Adhesion Promotion 3.3 Resist Spin Coating, Softbake, and Hardbake 3.4 Photochemistry of Novolak/DNQ g- and i-line Resists 3.5 Acid-Catalyzed DUV Resists 3.6 Development and Post-Exposure Bakes 3.7 Operational Characterization 3.8 Line-Edge Roughness 3.9 Multilayer Resist Processes Problems References Chapter 4 Modeling and Thin-Film Effects 4.1 Models of Optical Imaging 4.2 Aberrations 4.3 Modeling Photochemical Reactions 4.4 Thin-Film Optical Effects 4.5 Post-Exposure Bakes 4.6 Methods for Addressing the Problems of Reflective Substrates 4.7 Development 4.8 Quantum Effects and Modeling 4.9 Summary of Modeling Problems References Chapter 5 Wafer Steppers and Scanners 5.1 Overview 5.2 Light Sources 5.3 Illumination Systems 5.4 Reduction Lenses 5.5 Autofocus Systems 5.6 The Wafer Stage 5.7 Scanning 5.8 Dual-Stage Exposure Tools 5.9 Lithography Exposure Tools before Steppers Problems References Chapter 6 Overlay 6.1 Alignment Systems 6.1.1 Classification of alignment systems 6.1.2 Optical methods for alignment and wafer-to-reticle referencing 6.1.3 Number of alignment marks 6.2 Overlay Models 6.3 Matching 6.4 Process-Dependent Overlay Effects Problems References Chapter 7 Masks and Reticles 7.1 Overview 7.2 Mask Blanks 7.3 Mechanical Optical-Pattern Generators 7.4 Electron-Beam Lithography and Single-Beam Mask Writers 7.5 Multi-Electron-Beam Mask Writers 7.6 Optical Mask Writers 7.7 Resists for Mask Making 7.8 Etching 7.9 Pellicles 7.10 Mask-Defect Inspection and Repair Problems References Chapter 8 Confronting the Diffraction Limit 8.1 Off-Axis Illumination 8.2 Optical Proximity Effects 8.3 The Mask-Error Enhancement Factor (MEEF) 8.4 Phase-Shifting Masks 8.5 Putting It All Together Problems References Chapter 9 Metrology 9.1 Linewidth Measurement 9.1.1 Linewidth measurement using scanning electron microscopes 9.1.2 Scatterometry 9.1.3 Electrical linewidth measurement 9.2 Measurement of Overlay Problems References Chapter 10 Immersion Lithography and the Limits of Optical Lithography 10.1 Immersion Lithography 10.2 The Diffraction Limit 10.3 Improvements in Optics 10.4 Maximum Numerical Aperture 10.5 The Shortest Wavelength 10.6 Improved Photoresists 10.7 Flatter Wafers 10.8 How Low Can k1 Go? 10.9 How Far Can Optical Lithography Be Extended? 10.10 Multiple Patterning 10.11 Interferometric Lithography Problems References Chapter 11 Lithography Costs 11.1 Cost-of-Ownership 11.1.1 Capital costs 11.1.2 Consumables 11.1.3 Mask costs 11.1.4 Rework 11.1.5 Metrology 11.1.6 Maintenance costs 11.1.7 Labor costs 11.1.8 Facilities costs 11.2 Mix-and-Match Strategies Problems References Chapter 12 Extreme Ultraviolet Lithography 12.1 Background and Multilayer Reflectors 12.2 EUV Lithography System Overview 12.3 EUV Masks 12.4 Sources and Illuminators 12.5 EUV Optics 12.6 EUV Resists Problems References Chapter 13 Alternative Lithography Techniques 13.1 Proximity X-ray Lithography 13.2 Electron-Beam Direct-Write Lithography 13.2.1 Single-beam direct-write systems 13.2.2 Multiple-electron-beam direct-write systems 13.2.3 Cell-projection lithography 13.2.4 Scattering-mask electron-projection lithography 13.3 Ion-Projection Lithography 13.4 Imprint Lithography 13.5 Directed Self-Assembly Problems References Appendix A Coherence Problems References
