Emerging Non-Volatile Memories (eBook)

Preface 6
Memory Technology Evolution and Need for New Memory Concepts 6
Outline of This Book 7
Chapter 1: Ferroelectric Nonvolatile Memories (FeRAM) 7
Chapter 2: Magnetic Nonvolatile Memories (MRAM) 8
Chapter 3: Multiferroic Memories 8
Chapter 4: Phase-Change Memories (PCRAM) 8
Chapter 5: Oxide Resistance Random Access Memories (OxRRAM) 8
Chapter 6: Oxide-Based Memristive Nanodevices 9
Chapter 7: Ferroelectric Probe Storage Devices 9
Contents 10
Contributors 12
Part I: Ferroic Memories 14
Chapter 1: Review of the Science and Technology for Low- and High-Density Nonvolatile Ferroelectric Memories 15
1.1 Introduction 15
1.2 Ferroelectric Thin Film Synthesis and Characterization 18
1.2.1 Magnetron Sputter Synthesis and Characterization of Ferroelectric Thin Films and Heterostructures 18
1.2.2 Ion Beam Sputter Synthesis and Characterization of Ferroelectric Thin Films and Heterostructures 19
1.2.2.1 SIBMT-Based Studies to Understand Processing–Microstructure–Property Relationships of Ferroelectric PZT Thin Films and Heterostructures 19
1.2.2.2 SIBMT-Based Studies to Understand Processing– Microstructure–Property Relationships of Ferroelectric SBT Thin Films and Heterostructures 21
1.2.3 Pulsed Laser Ablation Synthesis and Characterization of Ferroelectric Films and Heterostructures 23
1.2.3.1 Processing–Microstructure–Property Relationships of PZT Films and Integration with Semiconductor Substrates 23
1.2.3.2 Processing–Microstructure–Property Relationships of SBT Films and Integration with Semiconductor Substrates 24
1.2.4 Chemical Vapor Deposition and Characterization of Ferroelectric Thin Films 27
1.2.4.1 Standard Precursor Delivery Techniques for MOCVD Synthesis of PZT Films 27
1.2.4.2 Alternative Precursor Delivery Techniques for MOCVD Synthesis of PZT Thin Films 28
1.2.4.3 MOCVD Synthesis and Characterization of SBT Thin Films 29
1.3 Materials Integration Strategies for Low-Density FeRAMs 31
1.3.1 Critical PZT-Based FeRAM Materials Integration Issues 31
1.3.2 Critical SBT-Based FeRAM Materials Integration Issues 31
1.4 FeRAM Fabrication Issues for Integration with the 0.35–45 nm CMOS Device Generations 32
1.4.1 Stacked Cell Processing Issues 33
1.4.2 Process Sequence Control 36
1.5 Critical Basic Physics Problems of FeRAMs: Current Understanding and Technological Implications 38
1.5.1 Microscale FeRAMs 39
1.5.2 Nanoscale FeRAMs 40
1.6 Basic Unsolved Physics Problems Related to FeRAMs 40
1.6.1 Basic Science Issues 40
1.6.1.1 What Are the Finite Size Effects in Ferroelectric Capacitor Properties? How Small Can a Ferroelectric Capacitor Be and Still Exhibit Ferroelectric Behavior? 41
1.6.1.2 Stresses and the Role of Substrate-Film Interactions 42
1.6.1.3 Polarization Dynamics 42
1.6.1.4 Role of Defects 43
1.7 Future Directions 43
1.8 Conclusions 45
References 45
Chapter 2: Hybrid CMOS/Magnetic Memories (MRAMs) and Logic Circuits 48
2.1 Introduction to Spintronics Phenomena Used in MRAM 48
2.1.1 GMR Discovery and Launching of Spin electronics 48
2.1.2 Tunnel Magnetoresistance 49
2.1.3 Spin-Transfer Phenomenon 51
2.2 Magnetic Random Access Memories 56
2.2.1 MRAM Based on Field-Induced Magnetization Switching 56
2.2.2 Thermally Assisted FIMS MRAM 66
2.2.2.1 General Principle of Thermally Assisted Approach 66
2.2.2.2 Reducing the Heating Power Density 68
2.2.2.3 Write Selectivity and Protection Against Stray Fields 71
2.2.2.4 TA-MRAM with Soft Reference Layer 71
2.2.3 First Generation of Spin-Transfer Torque MRAM 72
2.2.4 Advanced MRAM Concepts 78
2.2.4.1 Perpendicular STT MRAM 78
2.2.4.2 Thermally Assisted STT-MRAM 82
2.2.4.3 STT-MRAM with Perpendicular Polarizer 84
2.2.4.4 Multibit MRAM Concepts 86
2.2.4.5 3-Terminals STT MRAM Concepts 87
2.2.5 Perspectives on MRAM 89
2.3 Beyond MRAM, CMOS/Magnetic Integrated Electronics 90
2.3.1 From CMOS Electronics to Integrated CMOS/Magnetic Electronics 90
2.3.1.1 Power Consumption in CMOS Circuits 90
2.3.1.2 Reduction of the Dynamic Power Consumption 95
2.3.1.3 Reduction of Standby Power Consumption 96
2.3.2 Examples of CMOS/Magnetic Integrated Devices 97
2.3.3 Modelling Tools for the Design of Hybrid CMOS/MTJ Circuits 99
2.3.4 Perspectives 106
References 107
Chapter 3: Emerging Multiferroic Memories 113
3.1 Introduction 113
3.2 Multiferroic Materials 114
3.3 Principles of Magnetoelectricity in Multiferroics 120
3.4 Multiferroic Materials for Memory Applications 121
3.4.1 Manganite Thin Films 123
3.4.2 BiMnO3 Thin Films 126
3.4.3 BiFeO3 Thin Films 127
3.4.3.1 Controlling Domain Structures in BiFeO3 130
3.4.3.2 Evolution of Magnetism and Domain Wall Functionality in BiFeO3 133
3.4.3.3 Magnetoelectric Coupling in BiFeO3 139
3.4.3.4 Routes to Enhance Properties in BiFeO3 140
3.4.4 Other Single-Phase Multiferroics 148
3.4.5 Horizontal Multilayer Structures 149
3.4.6 Vertical Nanostructures 150
3.5 Design of Multiferroic-Based Memories 151
3.5.1 Electric Field Control of Ferromagnetism 154
3.5.2 Multiferroic-Based Devices 160
3.6 Challenges for Multiferroic-Based Memories and Devices 162
3.7 Conclusions: Looking to the Future 163
References 163
Part II: Resistance and Phase Change Memories 177
Chapter 4: Phase-Change Materials for Data Storage Applications 178
4.1 The Basic Principle of Phase-Change Based Data Storage 178
4.2 The Crystalline Phase 180
4.3 From the Crystalline to the Amorphous Phase 183
4.3.1 Glass Formation 183
4.3.2 Glass Rigidity and Bond Constraint Theory 185
4.4 The Amorphous Phase 187
4.4.1 Atomic Structure 187
4.4.2 Electrical Properties 189
4.5 Crystallization of an Amorphous Bit 191
4.5.1 Classical Theory of Crystallization 191
4.5.2 Atomistic Modeling of Crystallization 193
4.6 Applications Employing Phase-Change Materials 194
4.6.1 Optical Storage 195
4.6.2 Electronic Storage 195
References 197
Chapter 5: Emerging Oxide Resistance Change Memories 203
5.1 Introduction 204
5.1.1 Overview of Oxide Resistance Change Memory 204
5.2 Resistance Change in Oxide-Based Materials 206
5.2.1 Resistance Switching Properties 206
5.2.2 Oxide-Based Resistance Memory Classifications 207
5.2.2.1 Binary Oxides 207
5.2.2.2 Perovskites 211
5.2.2.3 Solid Electrolyte Based Materials 213
5.2.2.4 Summary 214
5.3 Oxide RRAM Based Materials and Applications 214
5.3.1 RRAM Scaling 214
5.3.2 Oxide-Based Switches for RRAM 216
5.3.3 RRAM State of the Art 220
5.3.4 Summary 221
5.4 Outlook and Future of RRAM 223
5.4.1 Conclusion 224
References 224
Chapter 6: Oxide Based Memristive Nanodevices 227
6.1 Section 1: Switching mechanism 228
6.1.1 Introduction 228
6.1.2 Experiment 229
6.1.3 Switching Behavior 230
6.1.4 Switching Mechanism 233
6.2 Section 2: A Device Family 236
6.2.1 Concept of the Device Family 236
6.2.2 Realization of the Device Family 240
6.3 Section 3: Electroforming Mechanism 244
6.3.1 Introduction 244
6.3.2 Experiment 244
6.3.3 Gas Bubble Formation 245
6.3.4 Electroforming Mechanism 249
6.4 Section 4: Device Engineering 253
6.4.1 Introduction 253
6.4.2 Device Engineering by Seeding the Switching Centers 254
6.4.3 Electroforming-Free Devices with a Bi-layer Oxide 259
6.5 Section 5: Summary 261
References 262
Part III: Probe Memories 265
Chapter 7: Ferroelectric Probe Storage Devices 266
7.1 Introduction 266
7.2 Principle and History of Information Storage Devices 267
7.3 Understanding Key Processes of Information Storage 270
7.4 Ferroelectric Materials as Storage Media 273
7.5 Ferroelectric Hard Disk Drive 274
7.6 Conclusion 278
References 280