Advanced Interconnects for ULSI Technology

About the Editors xv List of Contributors xvii Preface xxi List of Abbreviations xxv Section I Low-k Materials 1 1 Low-k Materials: Recent Advances 3 Geraud Dubois and Willi Volksen 1.1 Introduction 3 1.2 Integration Challenges 5 1.3 Processing Approaches to Existing Integration Issues 10 1.4 Material Advances to Overcome Current Limitations 16 1.5 Conclusion 22 2 Ultra-Low-k by CVD: Deposition and Curing 35 Vincent Jousseaume, Aziz Zenasni, Olivier Gourhant, Laurent Favennec and Mikhail R. Baklanov 2.1 Introduction 35 2.2 Porogen Approach by PECVD 37 2.3 UV Curing 42 2.4 Impact of Curing on Structure and Physical Properties: Benefits of UV Curing 49 2.5 Limit/Issues with the Porogen Approach 57 2.6 Future of CVD Low-k 62 2.7 Material Engineering: Adaptation to Integration Schemes 68 2.8 Conclusion 70 3 Plasma Processing of Low-k Dielectrics 79 Hualing Shi, Denis Shamiryan, Jean-Francois de Marneffe, Huai Huang, Paul S. Ho and Mikhail R. Baklanov 3.1 Introduction 79 3.2 Materials and Equipment 80 3.3 Process Results Characterization 82 3.4 Interaction of Low-k Dielectrics with Plasma 85 3.5 Mechanisms of Plasma Damage 92 3.6 Dielectric Recovery 112 3.7 Conclusions 121 4 Wet Clean Applications in Porous Low-k Patterning Processes 129 Quoc Toan Le, Guy Vereecke, Herbert Struyf, Els Kesters and Mikhail R. Baklanov 4.1 Introduction 129 4.2 Silica and Porous Hybrid Dielectric Materials 130 4.3 Impact of Plasma and Subsequent Wet Clean Processes on the Stability of Porous Low-k Dielectrics 134 4.4 Removal of Post-Etch Residues and Copper Surface Cleaning 141 4.5 Plasma Modification and Removal of Post-Etch 193 nm Photoresist 146 Section II Conductive Layers and Barriers 173 5 Copper Electroplating for On-Chip Metallization 175 Valery M. Dubin 5.1 Introduction 175 5.2 Copper Electroplating Techniques 176 5.3 Copper Electroplating Superfill 177 5.4 Alternative Cu Plating Methods 182 5.5 Electroplated Cu Properties 184 5.6 Conclusions 186 6 Diffusion Barriers 193 Michael Hecker and René Hübner 6.1 Introduction 193 6.2 Metal-Based Barriers as Liners for Cu Seed Deposition 198 6.3 Advanced Barrier Approaches 212 6.4 Conclusions 221 Section III Integration and Reliability 235 7 Integration and Electrical Properties 237 Sridhar Balakrishnan, Ruth Brain and Larry Zhao 7.1 Introduction 237 7.2 On-Die Interconnects in the Submicrometer Era 237 7.3 On-Die Interconnects at Sub-100 nm Nodes 240 7.4 Integration of Low-k Dielectrics in Sub-65 nm Nodes 241 7.5 Patterning Integration at Sub-65 nm Nodes 248 7.6 Integration of Conductors in Sub-65 nm Nodes 252 7.7 Novel Air-Gap Interconnects 258 8 Chemical Mechanical Planarization for Cu-Low-k Integration 267 Gautam Banerjee 8.1 Introduction 267 8.2 Back to Basics 268 8.3 Mechanism of the CMP Process 268 8.4 CMP Consumables 271 8.5 CMP Interactions 276 8.6 Post-CMP Cleaning 281 8.7 Future Direction 287 References 288 9 Scaling and Microstructure Effects on Electromigration Reliability for Cu Interconnects 291 Chao-Kun Hu, René Hübner, Lijuan Zhang, Meike Hauschildt and Paul S. Ho 9.1 Introduction 291 9.2 Electromigration Fundamentals 293 9.3 Cu Microstructure 300 9.4 Lifetime Enhancement 306 9.5 Effect of Grain Size on EM Lifetime and Statistics 321 9.6 Massive-Scale Statistical Study of EM 326 9.7 Summary 329 10 Mechanical Reliability of Low-k Dielectrics 339 Kris Vanstreels, Han Li and Joost J. Vlassak 10.1 Introduction 339 10.2 Mechanical Properties of Porous Low-k Materials 340 10.3 Fracture Properties of Porous Low-k Materials 352 10.4 Conclusion 361 11 Electrical Breakdown in Advanced Interconnect Dielectrics 369 Ennis T. Ogawa and Oliver Aubel 11.1 Introduction 369 11.2 Reliability Testing 378 11.3 Lifetime Extrapolation and Models 397 11.4 Future Trends and Concerns 403 Section IV New Approaches 435 12 3D Interconnect Technology 437 John U. Knickerbocker, Lay Wai Kong, Sven Niese, Alain Diebold and Ehrenfried Zschech 12.1 Introduction 437 12.2 Dimensional Interconnected Circuits (3DICs) for System Applications 438 John U. Knickerbocker 12.3 Advanced Microscopy Techniques for 3D Interconnect Characterization 467 Lay Wai Kong, Sven Niese, Alain Diebold and Ehrenfried Zschech 12.4 Summary 486 13 Carbon Nanotubes for Interconnects 491 Mizuhisa Nihei, Motonobu Sato, Akio Kawabata, Shintaro Sato and Yuji Awano 13.1 Introduction 491 13.2 Advantage of CNT Vias 492 13.3 Fabrication Processes of CNT Vias 493 13.4 Electrical Properties of CNT Vias 496 13.5 Current Reliability of CNT Vias 498 13.6 Conclusion 501 14 Optical Interconnects 503 Wim Bogaerts 14.1 Introduction 503 14.2 Optical Links 505 14.3 The Case for Silicon Photonics 519 14.4 Optical Networks on a Chip 528 14.5 Integration Strategies 532 14.6 Conclusion 538 15 Wireless Interchip Interconnects 543 Takamaro Kikkawa 15.1 Introduction 543 15.2 Wireless Interconnect Technologies 547 15.3 Conclusion 561 References 561 Index