Metal Oxides for Non-volatile Memory: Materials, Technology and Applications

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Metal Oxides for Non-volatile Memory: Materials, Technology and Applications covers the technology and applications of metal oxides (MOx) in non-volatile memory (NVM) technology. The book addresses all types of NVMs, including floating-gate memories, 3-D memories, charge-trapping memories, quantum-dot memories, resistance switching memories and memristors, Mott memories and transparent memories. Applications of MOx in DRAM technology where they play a crucial role to the DRAM evolution are also addressed. The book offers a broad scope, encompassing discussions of materials properties, deposition methods, design and fabrication, and circuit and system level applications of metal oxides to non-volatile memory. Finally, the book addresses one of the most promising materials that may lead to a solution to the challenges in chip size and capacity for memory technologies, particular for mobile applications and embedded systems. Front Cover Metal Oxides for Non-Volatile Memory: Materials, Technology and Applications Copyright Contents Contributors Series editor biography Preface to the series Chapter 1: Introduction to non-volatile memory 1.1. Introduction and history 1.1.1. Outline of this work 1.2. Flash non-volatile memory 1.2.1. Programming- and erase-mechanism 1.2.2. NOR- and NAND-Flash 1.2.3. Performance and scaling issues 1.3. Novel concepts for non-volatile memories 1.3.1. Resistive switches 1.3.1.1. Memristive devices 1.3.1.2. Nanoionic effects 1.3.1.3. Switching kinetics and energy consumption 1.3.2. Magnetoresistive random access memories 1.3.2.1. Giant magnetoresistance 1.3.2.2. Tunnel magnetoresistance 1.3.2.3. Spin-transfer torque MRAM (STT-MRAM) Acknowledgements References Chapter 2: Resistive switching in metal-oxide memristive materials and devices 2.1. Mechanisms of resistive switching in metal-oxide memristive materials and devices 2.1.1. Classification of resistive switching 2.1.2. Operation mechanisms of memristive devices based on TMO and SiOx 2.2. Local analysis of resistive switching of anionic type 2.2.1. Conductive atomic force microscopy 2.2.2. Investigations of individual filaments by CAFM 2.2.3. Investigations of resistive switching in YSZ films by CAFM 2.2.3.1. Sample preparation 2.2.3.2. CAFM measurements technique 2.2.3.3. Effect of annealing on the CAFM images of YSZ films 2.2.3.4. Imaging of individual filaments by CAFM 2.2.3.5. Quantum size effects in the electron transport via individual filaments 2.3. Multiscale simulation of resistive switching in metal-oxide memristive devices 2.3.1. Phenomenological approach 2.3.2. Atomistic approach 2.4. Conclusions Acknowledgments References Chapter 3: Charge trapping NVMs with metal oxides in the memory stack 3.1. Introduction 3.2. History of charge trap memory devices 3.3. SONOS memory devices 3.3.1. Traps in the CT NV memory stack 3.3.2. Program and erase of CT memory device 3.4. CT memory cell reliability 3.4.1. SONOS endurance 3.4.2. Data retention 3.5. New materials for charge trap memory stack-Metal oxides 3.5.1. Why metal oxides in CT memory stack? 3.5.2. Charge trap memory stack with high-K metal oxides 3.5.2.1. High-K dielectric for blocking layer 3.5.2.2. High-K dielectric for tunneling layer 3.5.2.3. High-K dielectric for trap layer 3.5.3. TANOS with high-K metal oxide dielectric 3.5.3.1. Enhancement of TANOS stacks 3.5.3.2. Band gap engineered SONOS (BE-SONOS) with high-K dielectric 3.5.4. Metal oxides in FINFET based CT memory device References Chapter 4: Technology and neuromorphic functionality of magnetron-sputtered memristive devices 4.1. Features of magnetron sputtering 4.2. Performances and reproducibility of memristive devices 4.3. Functionality of memristors as elements for neuromorphic systems 4.4. Conclusions Acknowledgments References Chapter 5: Metalorganic chemical vapor deposition of aluminum oxides: A paradigm on the processstructure-properties relati ... 5.1. Introduction 5.2. Process kinetic modeling and simulation of the MOCVD of metal oxides: The case of Al2O3 films 5.2.1. Model characteristics 5.2.2. Bibliographic analysis on the chemical mechanisms and kinetic laws 5.2.3. Kinetic model development and validation 5.2.4. Optimization of an original reactor by process simulation 5.3. Local coordination affects properties: The case of amorphous Al2O3 barrier coatings 5.3.1. Microstructure of amorphous alumina films 5.3.2. Application examples of barrier function of amorphous alumina films 5.4. Concluding remarks Acknowledgements References Chapter 6: MOx materials by ALD method 6.1. Introduction 6.2. ALD fundamentals 6.2.1. Saturating self-limiting reactions 6.2.2. Deposition temperature 6.2.3. Precursors 6.3. ALD of oxides for memory devices 6.3.1. Atomic layer deposition of Al2O3 6.3.2. Atomic layer deposition of HfO2 and ZrO2 6.3.2.1. Chloride precursor-based ALD 6.3.2.2. Alkylamide precursor-based ALD 6.3.2.3. Cyclopentadienyl precursor-based ALD 6.3.2.4. Application of Hf-based oxides in memory storage devices 6.3.3. Atomic layer deposition of TiO2 6.3.4. Atomic layer deposition of Ta2O5 6.3.5. Atomic layer deposition of NiO 6.3.6. Atomic layer deposition of SiO2 6.4. Conclusions References Chapter 7: Nano-composite MOx materials for NVMs 7.1. Introduction 7.2. Experimental 7.2.1. Fabrication routes 7.2.1.1. Synthesis of nanocrystals embedded in metal oxide dielectrics by magnetron-sputtering 7.2.1.2. Synthesis of nanocrystals embedded in metal oxide dielectrics by ULE-IBS 7.2.2. Characterization techniques 7.2.2.1. Transmission electron microscopy 7.2.2.2. Atom probe tomography 7.2.2.3. XRD 7.2.2.4. FTIR 7.2.2.5. Electrical characterization 7.2.3. Synthesis of nanocrystals embedded in metal oxides by radio frequency magnetron sputtering 7.2.3.1. Synthesis of Ge-NCs in HfO2 host Properties of HfGeOx layers versus annealing treatment Evolution of trilayer structures with annealing treatment Electrical properties of the structures 7.2.3.2. Synthesis of Si-NCs in HfSiOx films by magnetron sputtering 7.2.4. Ultra-low energy Si implantation into HfO2-based layers 7.2.5. ULE-II synthesis of Si- and Ge-NCs memories using SiN/HfO2/SiO2 stacks 7.2.6. ULE-II synthesis of Ge-NCs memories using Al2O3 as gate oxide 7.3. Conclusion Acknowledgments References Chapter 8: MOx in ferroelectric memories 8.1. Introduction 8.2. Ferroelectricity-A material property 8.3. Negative capacitance in ferroelectrics 8.4. Ferroelectricity in hafnium oxide 8.4.1. Switching kinetics at nanoscale 8.4.2. Accumulative switching 8.5. Ferroelectric memories 8.5.1. 1T1C FeRAM implementation 8.5.2. Planar 1T FeFET implementation 8.5.3. 3D FeFET implementation 8.5.4. Ferroelectric tunnel junction 8.6. Summary and future prospects References Chapter 9: ``Metal oxides in magnetic memories´´: Current status and future perspectives 9.1. Introduction 9.1.1. Spintronics 9.1.2. Magnetic tunnel junction (MTJ) and tunneling magnetoresistance (TMR) 9.1.3. Spin-transfer torque 9.2. Magnetic random access memory (MRAM) 9.2.1. MRAM storage principle 9.2.2. MRAM read principle 9.2.3. Early MRAM concepts 9.2.4. State-of-the-art MRAMs 9.3. Metal oxides in MRAMs 9.3.1. Tunnel barrier and TMR magnitude 9.3.2. The importance of oxide on MTJ crystal structure 9.3.3. Tunnel barrier breakdown 9.4. Perspectives References Chapter 10: Correlated transition metal oxides and chalcogenides for Mott memories and neuromorphic applications 10.1. Introduction 10.2. Mott insulators and Mott transitions 10.2.1. Mott insulators: Definition 10.2.2. Insulator to metal transition in Mott insulators 10.2.3. Renowned examples of Mott and charge transfer insulators 10.2.3.1. The vanadium oxide (V1-xCrx)2O3 10.2.3.2. NiS2-xSex 10.2.3.3. AM4Q8 compounds 10.2.4. The famous example of VO2 that exhibit an IMT but not a Mott transition 10.3. Electric Mott transitions 10.3.1. Joule heating and thermally driven IMT 10.3.2. Electromigration and filling controlled IMT 10.3.3. Dielectric breakdown and bandwidth controlled IMT 10.4. Electric Mott transition by dielectric breakdown: Detailed mechanism 10.4.1. Phenomenology of the dielectric breakdown 10.4.2. The initial spark: Creation of hot electrons and electronic avalanche 10.4.3. Runaway process and creation of a conducting filamentary path 10.4.4. Non-volatile electric Mott transition: A consequence of lattice compression specific to Mott physics 10.5. Microelectronic applications of Mott insulators: Toward Mottronics 10.5.1. Mott memories 10.5.1.1. Mott memories based on a thermally driven mechanism 10.5.1.2. Mott memories based on filling-controlled mechanism 10.5.1.3. Mott memories based on bandwidth-controlled mechanism 10.5.1.3.1. Performances of Mott insulator based ReRAM devices 10.5.2. New components based on Mott insulators for neurocomputing 10.5.2.1. Artificial synapses 10.5.2.2. Artificial neurons 10.5.2.2.1. Neuristor based on NbO2 10.5.2.2.2. Leaky integrate and fire neuron based on Mott insulators 10.6. Conclusion References Chapter 11: The effect of external stimuli on the performance of memristive oxides 11.1. Introduction 11.2. Electrical field 11.3. Magnetic field 11.4. Thermochemical treatments 11.5. Strain 11.6. Radiation 11.7. Outlook References Chapter 12: Nonvolatile MOX RRAM assisted by graphene and 2D materials 12.1. MOX RRAM with graphene-based electrodes 12.1.1. Transparent and flexible graphene electrode 12.1.2. Low power dissipation graphene electrode 12.1.3. Scaling down of MOX RRAM by graphene edge electrode 12.1.4. Heat-resistant graphene electrode for high-temperature device 12.1.5. MOX RRAM with reduced graphene oxide (rGO) electrode 12.2. Modulating ion migration in MOX RRAM by 2D materials 12.2.1. Inducement of ion migration by sporadic 2D material fragments 12.2.2. Suppressing the over-growth of CF by 2D material barrier 12.2.3. Monitoring ion migration by 2D material barrier 12.2.4. Confining ion migration in MOX RRAM by 2D material defect engineering 12.3. MOX RRAM assisted by additional 2D intercalation layer 12.3.1. MOX RRAM with intrinsic 2D materials 12.3.2. Oxidized film of 2D materials for MOX RRAM 12.4. Conclusion References Chapter 13: Ubiquitous memristors on-chip in multi-level memory, in-memory computing, data converters, clock generation an ... 13.1. Introduction 13.2. Multi-level memory and in-memory arithmetic structures 13.3. ADC and DAC in-memory data converters 13.4. Memristor-based clock signal generators 13.5. Metastable memristive transmission lines 13.6. Conclusions Acknowledgment References Chapter 14: Neuromorphic applications using MOx-based memristors 14.1. Introduction on neuromorphic computing 14.2. Recap of MOx-based memristor technology 14.2.1. Switching mechanisms 14.2.2. State retention and volatile effects 14.2.3. Arrangement of devices into crossbars 14.3. Advanced memristor functionalities useful for neuromorphic applications 14.3.1. Multilevel operation 14.3.2. Memristor plasticity 14.3.2.1. Analog plasticity 14.3.2.2. Stochastic plasticity 14.3.3. Computing with spike timing and spike rate 14.3.4. Negative differential resistance enabling oscillation 14.4. Overview of neuromorphic concepts and system prototypes 14.4.1. Acceleration of neural networks and machine learning algorithms 14.4.2. Spike-based brain-inspired architectures 14.4.2.1. Memristive synapses 14.4.2.2. Memristive neurons 14.4.2.3. Routing solutions for reconfigurable networks 14.4.2.4. Brain-inspired architectures and systems 14.4.3. Non-spiking analog computing 14.5. Conclusions and outlook References Index Back Cover