What is NOR Flash?
NOR Flash is an electronically erasable and reprogrammable non-volatile computer storage medium that uses “NOR” logic gate circuits.
Origin of NOR Flash Technology
In 1980, Toshiba’s Fujio Masuoka applied for a patent for simultaneously erasable EEPROM, which was later named Flash.
In 1984, Masuoka presented the complete concept of NOR Flash at the IEEE conference.
In 1987, Toshiba commercialized NAND Flash.
In 1988, Intel launched the first commercial NOR Flash—”Flash Memory,” which completely changed the landscape previously dominated by EPROM and EEPROM.
Since then, NOR and NAND have coexisted and developed with their respective advantages.
Technological Evolution of NOR Flash
Parallel→Serial: In 1994, serial NOR Flash was introduced, shifting the interface from parallel to serial, saving I/O footprint, reducing power consumption, size, and cost.
Capacity Expansion: From the early 256Kb to2Gb for full capacity coverage, meeting various application needs.
Low Power Consumption: Vcc has decreased from 3.3V to 1.8V or even lower, adapting to the needs of IoT devices.
NOR Flash Process Nodes and Capacities
In 1988, Intel’s first commercial NOR Flash was 256Kbit.
In 2004, Intel launched90nm process NOR Flash, increasing storage density by 50%.
In 2017, Wuhan Xinxin introduced 45nm process, with a single chip capacity of 8Gb.
In 2023, Zhaoyi Innovation achieved 19nm process mass production, leading the industry.
Starting in 2025, products with 55nm and below processes will account for 67%, gradually phasing out traditional processes above 90nm.
Mainstream Technology Routes for NOR Flash—ETOX and SONOS
SONOS stands for Silicon-Oxide-Nitride-Oxide-Silicon and is a non-volatile memory technology based on charge trapping mechanism.
ETOX stands for Electron Tunneling Oxide device and uses a floating gate structure to achieve data storage.
ETOX and SONOS are the two main technology systems for NOR Flash. The market share of SONOS technology in the NOR Flash market has increased from less than 8% in 2018 to about 25% in 2024, especially becoming the mainstream choice in the 512Kb-64Mb capacity range, but in high-capacity and ultra-reliable scenarios, ETOX remains irreplaceable.
