Simon Sze, Inventor of Floating Gate MOSFET, Passes Away

Introduction

On November 6, 2023, the world lost a visionary in the field of semiconductor physics and technology, Dr. Simon Sze who invented Floating gate memory. With an illustrious career spanning several decades, Dr. Sze’s contributions to the realm of electronics and semiconductor devices have left an indelible mark on the industry.

Let’s take a closer look at his life, his groundbreaking achievements, and the enduring legacy he leaves behind.

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Early Life and Education

Dr. Simon Sze was born on March 21, 1936, in Nanjing, China. He grew up in Taiwan and exhibited an early passion for science and intellectual curiosity. This passion eventually led him to pursue a career in electrical engineering.

After completing his B.S. in Electrical Engineering at National Taiwan University in 1957, he embarked on a journey of academic excellence.

Dr. Sze continued his education in the United States, earning a master’s degree from the University of Washington in 1960.

However, it was at Stanford University where he made significant contributions to the understanding of electron transport in semiconductor devices, culminating in his Ph.D. in 1963.

Image Credits: NCTU Website

Background of Floating Gate by Simon Sze

From the 1990s to the 2000s, Non-Volatile Memories (NVMs), specifically in their Flash Floating Gate and Charge Trap (FFG&CT) versions, emerged as the driving force for integrated circuits, penetrating mass markets such as cameras, automotive applications, and later, the communication sector.

Almost everyone has now used a USB key, a Solid State Disk (SSD), stored data on a mobile phone, or operated a digital camera, underscoring the remarkable expansion and dominance of FFG&CT NVMs. These memory technologies supplanted DRAM and Logic circuits as the driving force behind nanoelectronics. NVMs have undergone numerous conceptual and architectural transformations over the past five decades, transitioning from niche products to mass production drivers.

To put this into perspective, consider the current availability of Multi-Deca Gigabit USB keys, utilizing FFG&CT in a NAND architecture, which are now offered at incredibly low prices, serving as both storage and code-sharing platforms.

In contrast, back in the 1980s, 256k NOR Erasable Programmable Read-Only Memory (EPROM) chips, requiring UV lamp erasure, were primarily used for professional applications, particularly for storing microcontroller programs.

Evolution of NVM

While NVMs have encountered various challenges in their two-dimensional (2D) scaling, the transition to three-dimensional (3D) multilevel cells (supporting up to 4 bits per cell) has allowed for increased bit density without relying on conventional device scaling. NAND FFG&CT memories have even achieved Terabit-level integration, employing intermediate floating gates or pseudo-floating gate charge trapping mechanisms. Their market size exceeded $52 billion in 2018, marking an unprecedented milestone. Furthermore, they are on track to replace traditional hard disk drives (HDDs) in computers and are becoming the preferred choice for equipping data centers with Solid State Disks (SSDs).

Two significant figures who have left an indelible mark on the history of Non-Volatile Memories research and development are Professor Simon M. Sze from NCTU, an IEEE Fellow and IEEE EDS Celebrated member (Figure 1a), and Professor Fujio Masuoka from Tohoku University, also an IEEE Fellow.

Read More: History of VLSI: Transistor to System-on-a-Chip

Invention of the Floating-Gate MOSFET by Simon Sze

NAND flash memory, a ubiquitous component in today’s consumer technology products, owes its existence to the pioneering work of two Bell Labs researchers, Simon Sze and Dawon Kahng.

Sze, whose contributions have left an indelible mark on the world of semiconductor technology, played a pivotal role in the invention of the floating-gate nonvolatile memory (NVM) memory device.

This breakthrough, akin to William Shockley’s discovery of the transistor effect and the integrated circuits developed by Jack Kilby and Robert Noyce, marked a significant milestone in semiconductor technology.

Sze and Kahng introduced the first floating-gate device in 1967, around the same period when IBM was making strides in dynamic random access memory (DRAM) cells.

Figure 1 Recent portraits of: (a) Simon M. Sze (by courtesy of Simon Sze) (b) Fujio Masuoka (by courtesy of Fujio Masuoka)

DRAM vs Flash

DRAM’s rapid adoption in personal computers during the 1970s was a testament to its capabilities. This effectively replaced magnetic core chip technology. However, the landscape of consumer technology was changing, and the DRAM market for traditional PCs was shrinking.

NAND flash is a type of nonvolatile memory that can retain data even when a device’s power is turned off. This makes it ideal for data storage applications. In contrast, DRAM functions as the “working memory” of a computer, designed for rapid data access and processing.

Unlike DRAM, which swiftly replaced older memory technologies, floating-gate NVM devices took around two decades to become commercialized.

Introduced in 1967, these devices made their way into end products by 1984. This included gaming devices and BIOS chips that accelerated PC boot times.

The widespread use of floating-gate NVM memory gained momentum in the 1990s due to the increasing demand for mobile handsets and memory cards.

Figure 2(a) First floating-gate memory (FGM) by Dawon Khang (left) and Simon Sze (right). (Courtesy of Simon Sze) and Figure 2(b) Band diagram of a Floating gate transistor structure during: (a) charge trapping,(b) storage and (c) detrapping (discharging) (Courtesy of Simon Sze)

Memory cards utilizing NAND flash for storing photographs posed a significant threat to the traditional film photography market.

However, the turning point for NAND flash memory came with the popularity of Apple’s i-series products. The market for NAND flash memory expanded significantly, eventually challenging the size of the DRAM market.

According to statistics, more than 30 billion electronic products using floating-gate memory have been shipped, with the total number expected to exceed 80 billion units within the next decade

Figure 3(a) MNOS structure (Wegener et al.): discrete charge trapping devices (Courtesy of Simon Sze) and Figure 3(b) Floating gate Avalanche-injection MOS (FAMOS) structure

Career and Research

After completing his education, Dr. Sze worked at Bell Labs until 1990, conducting pioneering research in semiconductor physics and technology.

Following this period, he returned to Taiwan and joined the faculty of National Chiao Tung University. Throughout his career, Dr. Sze made significant contributions in various areas, including MOSFET technology, semiconductor device physics, and semiconductor device reliability.

His influential work extended beyond the laboratory, as he authored and edited numerous books, including the seminal “Physics of Semiconductor Devices.” This book has become an essential reference in the field, educating generations of engineers and scientists on the intricacies of semiconductor devices.

Image Credits: Etsy

These are all the books written or edited by Simon Sze

1. Physics of Semiconductor Devices” by S. M. Sze
2. “Nonvolatile Memories: Materials, Devices and Applications” (2-volume set) by Tseung-Yuen Tseng and Simon M. Sze
3. “Semiconductor Devices: Physics and Technology” by S. M. Sze
4. “VLSI Technology” edited by S. M. Sze
5. “Modern Semiconductor Device Physics” edited by S. M. Sze

Recognition and Awards

Dr. Sze’s contributions did not go unnoticed. His exceptional teaching and research were acknowledged through a series of prestigious awards and honors, including:

1. IEEE EDS J.J. Ebers Award in 1991.
2. Membership in the National Academy of Engineering in the United States in 1995.
3. Academician of Academia Sinica, Taiwan, in 1994.
4. Foreign Member of the Chinese Academy of Engineering in China in 1998.
5. The Future Science Prize in 2021.
6. IEEE Celebrated Member in 2017.

Read More: CMOS: From Overlooked Innovation to Semiconductor Dominance

Legacy and Personal Life

Dr. Simon Sze’s impact on the world of semiconductor physics and technology is immeasurable. His pioneering work not only advanced the field but also significantly shaped the technology we use in our daily lives.

He leaves behind a rich legacy, having educated and inspired countless individuals in the world of electronics and semiconductor technology.

Outside of his professional achievements, Dr. Sze was a family man. He is survived by his wife of 62 years, Therese, and his children and grandchildren.

Conclusion

Dr. Simon Sze’s passing marks the end of an era in the world of semiconductor physics and technology. His pioneering work and commitment to education have created a lasting legacy that will shape the industry’s future.