Semiconductor flash memory is an indispensable component of modern electronic systems which has gained a strategic position in recent decades due to the progressive shift from computing to consumer (and particularly mobile) products as revenue drivers for Integrated Circuits (IC) companies. This book provides a comprehensive overview of the different technological approaches currently being studied to fulfill future memory requirements. Two main research paths are identified and discussed. Different "evolutionary paths" based on the use of new materials (such as silicon nanocrystals for storage nodes and high-k insulators for active dielectrics) and of new transistor structures (such as multi-gate devices) are investigated in order to extend classical floating gate technology to the 32 nm node. "Disruptive paths" based on new storage mechanisms or new technologies (such as phase-change devices, polymer or molecular cross-bar memories) are also covered in order to address 22 nm and smaller IC generations. Finally, the main factors at the origin of these phenomena are identified and analyzed, providing pointers on future research activities and developments in this area.
Preface vii
Chapter 1. Introduction 1
Chapter 2. Semiconductor Industry Overview 7
2.1. The cyclical semiconductor market 7
2.2. The leading IC companies 12
2.3. The world IC market distribution 17
2.4. Semiconductor sales by IC devices 19
2.5. The semiconductor memory market 22
2.6. The impressive price decline of IC circuits 26
2.7. Moores Law, the ITRS and their economic impacts 33
2.8. Exponential growth of manufacturing and R&D costs 46
2.9. The structural evolution of the semiconductor industry 56
2.10. Consolidation of the semiconductor memory sector 64
2.11. Conclusions 70
2.12. References 73
Chapter 3. Research on Advanced Charge Storage Memories 77
3.1. Key features of Flash technology 78
3.2. Flash technology scaling 87
3.3. Innovative paths in silicon NVM technologies 96
3.4. Research on advanced charge storage memories 97
3.4.1. Silicon nanocrystal memories 97
3.4.2. Silicon nanocrystal memories with high-k IPDs 112
3.4.3. Hybrid silicon nanocrystal/SiN memories with high-k IPDs 117
3.4.4. Silicon nanocrystal double layer memories with high-k IPDs 119
3.4.5. Metal nano-dots coupled with organic templates 121
3.4.6. High-k IPD-based memories 127
3.4.7. High-k/metal gate stacks for TANOS memories 136
3.4.8. FinFlash devices 139
3.4.9. Molecular charge-based memories 151
3.4.10. Effects of the few electron phenomena 159
3.5. Conclusions 163
3.6. References 164
Chapter 4. Future Paths of Innovation 171
4.1. 3D integration of charge-storage memories 172
4.2. Alternative technologies 185
4.2.1. Ferro RAMs 187
4.2.2. Magnetic RAMs 187
4.2.3. Phase-change RAMs 188
4.2.4. Conductive bridging RAMs 199
4.2.5. Oxide resistive RAMs 202
4.2.6. New crossbar architectures 206
4.3. Conclusion 215
4.4. References 216
Chapter 5. Conclusions 223
5.1. References 232
Index 233
