DRAM belongs to volatile memory, which is often referred to as memory. Today, let’s take a look at another important area of semiconductor storage, which is non-volatile memory (also known as flash memory cards, USB flash drives, SSD hard drives, etc.).
In my article “The Best of Semiconductor Storage (link)”, I introduced to you that in the early days, memory was divided into ROM (read-only memory) and RAM (random access memory). Later, it was gradually changed to a more rigorous way of calling volatile memory and non-volatile memory.
1950s-1970s: From ROM to EEPROM
Let’s start with the earliest ROMs.
The exact time of the birth of ROMs is not detailed in any of the available sources. We only know roughly that mask ROMs were available in the 1950s, after the invention of the integrated circuit.
Mask ROM is a true conventional ROM, called Mask Read Only Memory (MASK ROM).
This kind of traditional ROM is “engraved” directly into the memory, completely written, read-only, non-erasable, and non-modifiable. It was inflexible and had no way to correct the content if it was written incorrectly, so it had to be discarded.
Later, in 1956, Wen Tsing Chow, a Chinese-American scientist from Bosch Arma, officially invented the PROM (Programmable ROM).
At that time, Bosch Arma had a military background and was focused on missile, satellite and spacecraft guidance systems.
Wenjun Zhou invented the PROM, an on-board digital computer used in the U.S. Air Force’s intercontinental ballistic missiles. It can change the physical configuration of the memory by applying high-voltage pulses, thus enabling a single modification (programming) of the content.
Later, PROMs gradually appeared in civilian applications.
Some new types of PROMs, which can fuse the fuse by means of electric current or light (ultraviolet light) by means of special equipment, achieve the effect of rewriting data.
These PROMs, which were used in large numbers in game machines as well as industrial control, stored program codes.
In 1959, Mohamed M. Atalla (Mohamed Atalla, of Egyptian descent), an engineer at Bell Labs, invented the metal oxide semiconductor field effect transistor (MOSFET) together with Dawon Kahng (Dae Won Kang, of Korean descent).
After the invention of MOSFET, it was neglected by Bell Labs. After many more years, in 1967, Dawon Kang and Simon Min Sze (Min Sze, of Chinese descent) proposed a floating gate based on MOS semiconductor devices for reprogrammable ROM memory cells.
1950s-1970s: From ROM to EEPROM
Let’s start with the earliest ROMs.
The exact time of the birth of ROMs is not detailed in any of the available sources. We only know roughly that mask ROMs were available in the 1950s, after the invention of the integrated circuit.
Mask ROM is a true conventional ROM, called Mask Read Only Memory (MASK ROM).
This kind of traditional ROM is “engraved” directly into the memory, completely written, read-only, non-erasable, and non-modifiable. It was inflexible and had no way to correct the content if it was written incorrectly, so it had to be discarded.
Later, in 1956, Wen Tsing Chow, a Chinese-American scientist from Bosch Arma, officially invented the PROM (Programmable ROM).
At that time, Bosch Arma had a military background and was focused on missile, satellite and spacecraft guidance systems.
Wenjun Zhou invented the PROM, an on-board digital computer used in the U.S. Air Force’s intercontinental ballistic missiles. It can change the physical configuration of the memory by applying high-voltage pulses, thus enabling a single modification (programming) of the content.
Later, PROMs gradually appeared in civilian applications.
Some new types of PROMs, which can fuse the fuse by means of electric current or light (ultraviolet light) by means of special equipment, achieve the effect of rewriting data.
These PROMs, which were used in large numbers in game machines as well as industrial control, stored program codes.
In 1959, Mohamed M. Atalla (Mohamed Atalla, of Egyptian descent), an engineer at Bell Labs, invented the metal oxide semiconductor field effect transistor (MOSFET) together with Dawon Kahng (Dae Won Kang, of Korean descent).
After the invention of MOSFET, it was neglected by Bell Labs. After many more years, in 1967, Dawon Kang and Simon Min Sze (Min Sze, of Chinese descent) proposed a floating gate based on MOS semiconductor devices for reprogrammable ROM memory cells.
Architecture Comparison
With NOR Flash memory, per-bit random access is possible. NAND Flash, on the other hand, can only access multiple memory cells at the same time.
For NOR Flash, if any memory cell is selected by the corresponding word line, the corresponding bit line will become 0. This relationship is similar to the “NOR gate circuit”.
For NAND Flash, all memory cells on a bit line need to be 1 in order to make the bit line 0, similar to the “NAND gate circuit”.
Can’t understand it? It’s okay, but remember: NAND Flash is cheaper than NOR Flash.
1988~2000: The Herd Rises Up and Competes for Flash
FLASH (flash memory) products emerged and gained recognition from users because of their advantages in capacity, performance, size, reliability, and energy consumption. Intel also made a lot of money with its pioneering flash memory products and achieved an industrial leadership.
Funny enough, after Intel’s success, Toshiba not only did not reflect on its mistakes, but claimed that FLASH was Intel’s invention, not that of its own employee, Fujio Misakioka.
It was only in 1997 that Toshiba officially changed its mind when the IEEE gave a special contribution award to Fujio Misakioka.
This infuriated Fujio Misakioka, who later (in 2006) sued the company and demanded 1 billion yen in compensation. In the end, he settled with Toshiba and was awarded 87 million yen ($758,000).
In 1988, Eli Harari (Eli Harari) and others, officially founded SanDisk Corporation (SanDisk, then called SunDisk).
In 1989, SunDisk filed a patent for a system flash architecture (“System Flash”) that combined an embedded controller, firmware, and flash memory to emulate disk storage. That year, Intel began shipping 512K and 1MB NOR Flash.
In 1989, another very important event in the flash memory industry was the birth of a company called M-Systems in Israel. They first introduced the concept of flash drives, which later became known as flash SSD drives.
As we entered the 1990s, FLASH technology began to shine as the market demand for digital cameras, laptops, etc. exploded.
In 1991, SunDisk launched the world’s first ATA SSD (solid state disk) based on FLASH flash media with a capacity of 20MB and a size of 2.5 inches.
Toshiba also began to make a push, successively launched the world’s first 4MB and 16MB NAND Flash.
In 1992, Intel held 75% of the FLASH market share. In second place was AMD, with only 10%. In addition to the two of them and SanDisk, the industry also crowded in SGS-Thomson, Fujitsu and other companies, and competition began to gradually become increasingly fierce.
This year, AMD and Fujitsu have launched their own NOR Flash products. Flash memory chip industry annual revenue reached $295 million.
In 1993, the United States Apple officially launched the Newton PDA products. It used, among others, NOR Flash memory.
In 1994, SanDisk was the first company to launch a CF memory card (Compact Flash). At the time, this memory card was based on Nor Flash flash technology and was used in products such as digital cameras.
In 1995, M-Systems released DiskOnChip, a NOR Flash-based flash drive.
In 1996, Toshiba introduced the SmartMedia card, also known as a solid-state floppy card. Soon after, Samsung began shipping NAND flash memory, and SanDisk introduced the first flash memory card using MLC serial NOR technology.
In 1997, cell phones began to be equipped with flash memory. From then on, flash memory opened up a huge consumer-level market after digital cameras.
In this year, Siemens and SanDisk collaborated to develop the famous MMC card (MulTI Media Memory) using Toshiba’s NAND Flash technology.
In August 1999, because MMC could easily pirate music, Toshiba modified it by adding encryption hardware and named it SD (Secured Digital) card.
Later, there were MiniSD, MicroSD, MS Micro2 and Micro SDHC, which I am sure the post-70s and post-80s partners are very familiar with.
Throughout the late 90s, benefiting from the explosion of consumer digital products such as cell phones, digital cameras, portable video cameras and MP3 players, the market size of FLASH increased rapidly. At that time, the market was booming, and the number of participating companies was also large. Among them, the most competitive ones were Samsung, Toshiba, SanDisk and Intel.
In 2000, M-Systems and Trek released the world’s first commercial USB flash drive, which we are very familiar with as a USB flash drive.
It also had a name, called a thumb drive
At the time, USB flash drives were complicated to patent, with several companies claiming to own their patents. China’s Lanxess, too, received a foundational patent for the USB flash drive in 1999.
2000~2012: NAND rose and NOR lost its power
NAND Flash has been on the rise since the late 90s. In the 21st century, the rise was even more rapid.
In 2001, Toshiba and SanDisk announced the launch of 1GB MLC NAND. SanDisk itself launched its first NAND system flash product.
In 2004, the price of NAND dropped below DRAM for the first time based on equivalent density. The huge cost effect began to push computers into the flash memory era.
In 2007, cell phones entered the smartphone era, again impacting the technology landscape of the flash memory market.
In the previous feature phone era, cell phones did not require much memory, and NOR Flash was a code-based flash chip that was widely used thanks to the XiP architecture of NOR+PSRAM (XiP, Execute In Place, i.e., applications no longer had to read code into system RAM, but could run directly in Flash memory).
In the era of smartphones, with application stores and massive APPs, the shortcomings of small capacity and high cost of NOR Flash could not meet the needs of users anymore.
As a result, NOR Flash’s market share began to be replaced by NAND Flash in large numbers, and the market continued to shrink.
Around 2008, eMMC, which was developed from MMC, became the mainstream technology for smartphone storage.
The eMMC is the embedded MulTI Media Card, which packages the MMC (multimedia card) interface, NAND and main controller in a small BGA chip, mainly to solve problems such as NAND brand difference compatibility, and facilitate manufacturers to launch new products quickly and simply.
Later, in 2011, the UFS (Universal Flash Storage) 1.0 standard was born, and UFS gradually replaced eMMC as the mainstream storage solution for smartphones. Of course, UFS is also based on NAND FLASH.
SSD hard drive side, not to mention, basically all use NAND chips.
Around 2015, companies like Samsung, Magnesium, Cypress, etc., all gradually withdrew from the NOR Flash market and focused on fighting in the NAND Flash field.
2012~now: the current state of the flash memory industry
The formation of market monopoly pattern
After 2011, the entire flash memory industry was in turmoil with numerous acquisitions.
During that period, LSI acquired Sandforce, SanDisk acquired IMFT, Apple acquired Anobit, and Fusion-io acquired IO Turbine. 2016 saw an even heavier acquisition – Western Digital acquired SanDisk.
Through consolidation of mergers and acquisitions, the NAND Flash market became less and less of a player.
Eventually, a concentrated market dominated by giants such as Samsung, Armor Man (Toshiba), Western Digital, Magnesium, SK Hynix, and Intel was formed. This has been the case until now.
In the NAND flash market, these giants have a combined share of over 95%. Among them, Samsung’s market share is the highest, arriving at 33-35%.
The Coming of 3D NAND Era
As mentioned in the previous DRAM article, around 2012, as the 2D process gradually entered a bottleneck, semiconductors began to enter the 3D era.
In 2012, Samsung officially launched the first generation of 3D NAND flash chips. Subsequently, SanDisk, Toshiba, Intel, Western Digital have released 3D NAND products. Flash memory industry officially entered the 3D era.
Since then, 3D NAND technology has continued to evolve, the number of stacked layers has increased and the capacity has become larger and larger.
3D NAND exists in a variety of routes. Take Samsung for example, in the early days, Samsung also studied a variety of 3D NAND solutions. Eventually, they chose to mass produce V-NAND flash memory with VG vertical gate structure.
Currently, according to media sources, Samsung has completed the development of the eighth generation V-NAND technology product, which will use 236-layer 3D NAND flash chips with a single Die capacity of 1Tb and an operating speed of 2.4Gb/sec.
Samsung has the largest market share, but they do not have the largest number of layers.
In May this year, Magnesium has announced the launch of 232 layers of 3D TLC NAND flash memory and is ready to start production in late 2022. SK Hynix, in South Korea, has even released 238 layers.
NOR ushered in the second spring
Let’s talk about NOR Flash.
As we mentioned earlier, NOR Flash has been gradually abandoned by the market since 2005.
By 2016, NOR Flash market size was considered to have hit the bottom.
Who would have thought that the negative would come back, these years, NOR Flash has ushered in a new lease of life.
Wearable devices represented by TWS headphones, AMOLED (active matrix organic light emitting diode panels) and TDDI (touch screen) technologies for cell phone screen display, and the increasingly powerful field of automotive electronics have generated great demand for NOR Flash and driven a strong recovery of the NOR Flash market.
Starting from 2016, the NOR Flash market has been gradually expanding in size.
As a result of this favorable impact and the fact that many large manufacturers have previously abandoned or scaled down NOR Flash (Magnesium and Cypress continue to reduce production), some second-tier companies have gained opportunities.
Among them, it includes Taiwan’s Macronix and Huabang, and mainland China’s Zhaoyi Innovation. These three companies have a market share of about 26%, 25% and 19%, adding up to over 70%.
Localization of FLASH Flash Memory
In terms of localization, NAND Flash is noteworthy for Changjiang Storage.
Formally established on July 26, 2016 on the basis of Wuhan Xinxin Integrated Circuit Manufacturing Co., Ltd. with major shareholders including China Integrated Circuit Industry Investment Fund and Ziguang Group, Hubei government, etc., Changjiang Storage is dedicated to providing integrated services in 3D NAND flash memory design, manufacturing and memory solutions.
In 2020, CK Storage announced the successful development of two 128-layer TLC/QLC products and the launch of two new consumer SSDs in the Chi-Ti series.
By the end of 2021, CK Storage has reached a production capacity of 100,000 wafers per month. By the first half of 2022, mass production of NAND with 128-layer architecture has been completed.
Currently, CK Storage is working on the challenge of 232-layer NAND, trying to close the process gap as soon as possible to catch up with the international majors.
In terms of NOR Flash, GigaDevice has just been mentioned.
Founded in 2005, GigaDevice is a global chip design company headquartered in China, and in 2012, they were the largest local designer of code-based flash memory chips in mainland China.
Currently, they are ranked third in the world in NOR Flash, and in 2021, ZTE will ship approximately 3.288 billion memory chips (mainly NOR Flash), ranking second in the world.
Conclusion
In recent years, as you can see, with the declining price of FLASH chips, individual home and business users are beginning to adopt flash memory on a large scale, as well as SSD hard drives. shipments of SSD hard drives, gradually overtaking HDD mechanical hard drives. Storage media replacement, and into a new peak.
In the future, the market share of flash memory will be further expanded. In such a trend, not only our personal and home users’ storage experience will become better, the whole society’s demand for storage power can also be further satisfied.
Semiconductor storage, will play a greater role for the digital transformation of all mankind.
Review Editor: Liu Qing
