Magnetic Memory Technology: Spin-transfer-Torque MRAM and Beyond

Magnetic Memory Technology: Spin-transfer-Torque MRAM and Beyond

by Denny D. Tang, Chi-Feng Pai


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Magnetic Memory Technology: Spin-Transfer-Torque MRAM and Beyond delivers a combination of foundational and advanced treatments of the subjects necessary for students and professionals to fully understand MRAM and other non-volatile memories, like PCM, and ReRAM. The authors offer readers a thorough introduction to the fundamentals of magnetism and electron spin, as well as a comprehensive analysis of the physics of magnetic tunnel junction (MTJ) devices as it relates to memory applications.

This book explores MRAM's unique ability to provide memory without requiring the atoms inside the device to move when switching states. The resulting power savings and reliability are what give MRAM its extraordinary potential. The authors describe the current state of academic research in MRAM technology, which focuses on the reduction of the amount of energy needed to reorient magnetization.

Among other topics, readers will benefit from the book's discussions of:

  • An introduction to basic electromagnetism, including the fundamentals of magnetic force and other concepts
  • An thorough description of magnetism and magnetic materials, including the classification and properties of magnetic thin film properties and their material preparation and characterization
  • A comprehensive description of Giant magnetoresistance (GMR) and tunneling magnetoresistance (TMR) devices and their equivalent electrical model
  • Spin current and spin dynamics, including the properties of spin current, the Ordinary Hall Effect, the Anomalous Hall Effect, and the spin Hall effect
  • Different categories of magnetic random-access memory, including field-write mode MRAM, Spin-Torque-Transfer (STT) MRAM, Spin-Orbit Torque (SOT) MRAM, and others

Perfect for senior undergraduate and graduate students studying electrical engineering, similar programs, or courses on topics like spintronics, Magnetic Memory Technology: Spin-Transfer-Torque MRAM and Beyond also belongs on the bookshelves of engineers and other professionals involved in the design, development, and manufacture of MRAM technologies.

Product Details

ISBN-13: 9781119562238
Publisher: Wiley
Publication date: 01/07/2021
Pages: 352
Product dimensions: 0.39(w) x 0.39(h) x 0.39(d)

About the Author

DENNY D. TANG, PHD, has been with IBM Watson and later Almaden Research Center, TSMC, and held a position as MRAM Architect in Western Digital. He Is a Live Fellow of IEEE, Fellow of TSMC Academy, a co-author of Magnetic Memory, Fundamentals and Technology, (2010).

CHI-FENG PAI, PHD, is now an Associate Professor of National Taiwan University (NTU). He is the recipient of Young Researcher Award of Asian Union of Magnetic Society (AUMS), Young Researcher Fellowship of Ministry of Science and Technology (MOST, Taiwan), and Young Researcher Award of Taiwan Semiconductor Industry Association (TSIA).

Table of Contents

Preface xi

Author Biographies xiv

List of Cited Tables and Figures xvi

1 Basic Electromagnetism 1

1.1 Introduction 1

1.2 Magnetic Force, Pole, Field, and Dipole 1

1.3 Magnetic Dipole Moment, Torque, and Energy 3

1.4 Magnetic Flux and Magnetic Induction 5

1.5 Ampère’s Circuital Law, Biot-Savart Law, and Magnetic Field from Magnetic Material 6

1.6 Equations, cgs-SI Unit Conversion Tables 11

2 Magnetism and Magnetic Materials 19

2.1 Introduction 19

2.2 Origin of Magnetization 19

2.3 Classification of Magnetisms 28

2.4 Exchange Interactions 42

2.5 Magnetization in Magnetic Metals and Oxides 49

2.6 Phenomenology of Magnetic Anisotropy 51

2.7 Origins of Magnetic Anisotropy 54

2.8 Magnetic Domain and Domain Walls 57

3 Magnetic Thin Films 67

3.1 Introduction 67

3.2 Magnetic Thin Film Growth 67

3.3 Magnetic Thin Film Characterization 72

4 Magnetoresistance Effects 77

4.1 Introduction 77

4.2 Anisotropic Magnetoresistance (AMR) 78

4.3 Giant Magnetoresistance (GMR) 79

4.4 Tunneling Magnetoresistance (TMR) 81

4.5 Contemporary MTJ Designs and Characterization 84

5 Magnetization Switching and Field MRAMs 93

5.1 Introduction 93

5.2 Magnetization Reversible Rotation and Irreversible Switching Under External Field 93

5.3 Field MRAMs 99

6 Spin Current and Spin Dynamics 105

6.1 Introduction to Hall Effects 105

6.2 Spin Current 109

6.3 Spin Dynamics 116

6.4 Interaction Between Polarized Conduction Electrons and Local Magnetization 124

6.5 Spin Current Interaction with Domain Wall 134

7 Spin-Torque-Transfer (STT) MRAM Engineering 151

7.1 Introduction 151

7.2 Thermal Stability Energy and Switching Energy 152

7.3 STT Switching Properties 154

7.4 The Integrity of MTJ Tunnel Barrier 166

7.5 Data Retention 169

7.6 The Cell Design Considerations and Scaling 173

7.7 MTJ SPICE Models 188

7.8 Test Chip, Test, and Chip-Level Weak Bit Screening 191

8 Advanced Switching MRAM Modes 205

8.1 Introduction 205

8.2 Current-Induced-Domain-Wall Motion (CIDM) Memory 206

8.3 Spin-Orbit Torque (SOT) Memory 211

8.4 Magneto-Electric Effect and Voltage-Control Magnetic Anisotropy (VCMA) MRAM 224

8.5 Relative Merit of Advanced Switching Mode MRAMs 231

9 MRAM Applications and Production 241

9.1 Introduction 241

9.2 Intrinsic Characteristics and Product Attributes of Emerging Nonvolatile Memories 242

9.3 Memory Landscape and MRAM Opportunity 247

9.4 MRAM Production 266

Appendix A Retention Bake (Including Two-Way Flip) 277

Appendix B Memory Functionality-Based Scaling 279

Appendix C High-Bandwidth Design Considerations for STT-MRAM 299

Index 323

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