1. 1 THE FLOATING ━ GATE MEMORY EFFECT From Discovery to the Digital Age S. M. SZE National Chiao Tung University Hsinchu, Taiwan, ROC

2. OUTLINE  INTRODUCTION  THE FLOATING-GATE MEMOTY EFFECT  HISTORICAL DEVELOPMENT  APPLICATIONS  SCALING CHALLENGES  ALTERNATIVE STRUCTURES  CONCLUSION

3. HISTORICAL EVOLUTION OF MEMORY

4. CLASSIFICATION OF DIGITAL MEMORY FGM

5. DRAWBACKS OF HDD AND OPTICAL DISK Low density Slow access time Large form factor High power consumption Non-compatible with CMOS technology

6.  THE FLOATING-GATE MEMORY (FGM) EFFECT

7. FIRST PAPER ON FLOATING-GATE MEMORY EFFECT (by D. Kahng and S. M. Sze in May 1967)

8. CROSS - SECTIONAL VIEW OF A FLOATING-GATE MEMORY

9. FIRST PAPER ON FGM EFFECT (1967)  In the mid 1960s magnetic core memory was the dominant nonvolatile memory for computers. Such memory was considered not possible in a semiconductor because of its short lifetime (~1ms)  The possibility of nonvolatile storage in semiconductors device was recognized for the first time in the 1967 paper, and an experimental EEPROM was demonstrated (>1 hr storage time)  The paper introduced not only the basic concept of nonvolatility in semiconductor, but also the floating-gate structure which has been the dominant technology for nonvolatile information storage

10. BAND DIAGRAM OF FGM OPERATIONS (Programming, Storage, and Erase)

11. CURRENT DENSITY EQUATIONS For Fowler-Nordheim Tunneling For Hot-Electron Injection

12. THRESHOLD VOLTAGE SHIFT DUE TO CHARGE STORAGE IN THE FLOATING GATE

13. FIRST EXPERIMENTAL RESULT OF FGM OPERATION IN 1967 (The storage time was one hour)

14.  HISTORICAL DEVELOPMENT

15. HISTORY OF FGM YEAR DEVICE DISCOVERER (S)/INVENTOR(S) ORGANIZATION 1967 Floating-Gate Concept Kahng and Sze Bell Labs 1971 EPROM-FAMOS Frohman-Bentchkowsky Intel 1976 EEPROM-SAMOS lizuka et al. Toshiba 1984 Flash Memory Masuoka et al. Toshiba 1987 NAND Flash Masuoka et al. Toshiba 1995 Multilevel Cell Bauer et al. Intel 2010 Multi-layer Integration Whang et al. Hynix 2014 128Gb MLC Helm et al. Micron NAND Flash 2016 768Gb MLC Tanaka et al. Micron NAND Flash

18. NOR AND NAND ARCHITECTURES

19. CLASSIFICATION OF FGM EPROM (Electrically Programmable Read Only Memory) EEPROM (Electrically Erasable Programmable Read Only Memory) Flash Memory ‧ NOR Flash (with a basic unit of one memory device) ‧ NAND Flash (with a basic unit of 16 or more memory devices)

20. MARKET SHARE OF THREE FGM PRODUCTS

21. SINGLE-LEVEL AND MULTI-LEVEL CELLS

22. MULTI-CHIP STACKING WITH TSV

23. DUAL CONTROL-GATE WITH SURROUNDING FLOATING-GATE NAND FLASH

24. 128 Gb NAND FLASH MEMORY ( 1.8 V 16 nm 173 mm 2 0.0013μm 2 /cell )

25. CROSS SECTIONAL VIEW OF 768GB 3b/CELL 3D FLOATING-GATE NAND FLASH MEMORY

26. MOORE’S LAW

27. UNIQUE FEATURES OF FG MEMORY Nonvolatility — long term storage (10-100 years) is maintained after the source of power is discontinued High bit density — FGM (NAND Flash) has the smallest area/cell among all digital memories Low power consumption — FGM consumes the least power/cell among all digital memories (10% of HDD, 1% of DRAM) Compatible with CMOS technolog y

28.  APPLICATIONS

29. COST PER GIGABYTE OF HDD AND NAND FLASH

30. APPLICATIONS OF FLOATING-GATE MEMORY Because of its unique features, FGM has served as a foundation technology for breakthroughs that have touched virtually every aspect of human existence: Automation and Machinery 4Cs (Car, Communication, Computing, Consumer Electronics) Health Care (Personal, Predictive, Preventive) Sustainable Development (Culture, Energy, Environment)

31. AUTOMATION AND MACHINERY FGM-based technology has provided better automation systems Laser printers, inkjet printers and copies for high-speed high-resolution printing, copying, and scanning 3D printers to generate toys, industrial tools, and bio- printing of tissues FGM-based technology has provided more precise servo control, motor control and robotics

32. CAR, COMMUNICATION, COMPUTING, and CONSUMER ELECTRONICS Car: 50 to 100 FGM-based microcontroller units (MCUs) are installed in each modern car to improve its performance and travel safety; to develop next- generation cars from information-connected to autonomous self-driving Communication: FGM-based cellular phone is considered the most useful invention of all time (over 7 billion cellular phone subscribers in the world) Computing: billions of FGM-based tablet computers and USB memory sticks are in use today. FGM (especially NAND Flash) is the preferred digital memory for big data, cloud computing, internet of everything (IoE) and solid-state drive (SSD) Consumer Electronics: billions of digital TV, DVD players. MP3 music players provide more engaging media. FGM also enables the development of digital cameras, digital camcorders, dictionaries, games, toys, electronic books, smart IC cards, electronic toll collection systems, and bar-code readers

33. 4 TB SOLID-STATE DRIVE (4 x 10 12 Bytes) (to store 1 million copies of the Bible, a half million songs, or 400 movies)

34. PENETRATION RATE IN ELECTRONICS INDUSTRY FGM

35. FGM APPLICATIONS IN ELECTRONICS INDUSTRY

36. ANNUAL PRODUCTIONS OF SELECTED DIGITAL ELECTRONIC PRODUCTS FGM

37. HEALTH CARE FGM-based implantable systems (pacemakers, defibrillators) can monitor heart patients FGM-based portable systems (EKG monitors, ultrasound scanners) can bring modern medicine to remote areas FGM-based 3D printers will be used for tissue engineering of human organs for transplantation FGM-based advanced micro-surgery technology (e.g., the deVinci robot) can provide minimally invasive surgical procedures

38. SUSTAINABLE DEVELOPMENTS Cultural Preservation — digital archiving: by using FGM as the new paper, SSD as the new book, and cloud data center as the new library, we can preserve our cultural heritage and accumulated knowledge in an ultra-small space. For example, the content of a typical large library can be stored in 100 TB (100 x10 12 bytes) SSDs with a volume smaller than a textbook, and all stored information can be easily accessed via cloud computing Energy Conservation — By using FGM-based smart systems, we can increase the energy efficiency of household appliances by 30%. Adoptions of FGM-based MCUs for buildings will result in a 50% reduction of electricity usage by 2030 Environmental Protection — In the past 35 years. European automobile industry has reduced CO 2 emission by 90% and fuel consumption by 35%, during the same 35 years period the traffic density increased by 250%

39.  SCALING CHALLENGES

40. HALF PITCH FOR FGM

41. SCALING CHALLENGES Retention of 10 ~ 20 years Endurance of program/erase cycles Interference of neighboring cells Reduction of coupling ratio Reduction of number of electrons Dielectric leakage Variability of doping and line edge roughness Random telegraph noise

42.  ALTERNATIVE STRUCTURES

43. ALTERNATIVE STRUCTURES (RETAINING STORAGE PRINCIPLE)

44. EMERGING NON-VOLATILE MEMORIES FeRAM ( Ferroelectric Random Access Memory ) : based on remanent polarization in Perovskite materials PCRAM ( Phase-Change RAM ) : based on reversible phase convertion between the amorphous and crystalline state of a chalcogenide glass which is accomplished by heating and cooling of the glass RRAM ( Resistance RAM ) : based on change in resistance with applied electric field, e.g., in lead zirconium titanate and tantalum pentoxide STT- MRAM ( Spin-torque - transfer Magnetic RAM) : based on spin polarization that can be used to control the magnetic orientation of layers in an MRAM cell

45. EMERGING NON-VOLATILE MEMORIES ˙FeRAM ˙PCRAM ˙RRAM ˙STT-MRAM

46. THE UNIFIED MEMORY WITH HIGH SPEED, HIGH DENSITY, AND NONVOLATILITY

47. TECHNOLOGY DRIVER OF THE ELECTRONICS INDUSTRY (1910 to present )

48. CONCLUSION The floating-gate memory has revolutionized information-storage technology and ushered in the Digital Age Since 1990 FGM has been the prime technology driver of the electronics industry, and enabled the development of all modern electronic systems FGM has become omnipresent, every person in the world has, on average, over 300 billion FGM cells Many innovations are being made to overcome the scaling challenges, and a Unified Memory may be developed to improve system performances FGM inspired technology has brought unprecedented benefit to humankind, and will continue to enrich and improve our lives for decades to come