Development of ETOX NOR Flash Memory

ETOX NOR flash memory was developed in the mid‐1980s at Intel to provide the in‐system alterability function of an EEPROM (Electrically Erasable Programmable Read Only Memory) at a product cost approaching that of an EPROM (Erasable Programmable Read Only Memory). The culmination of this effort was a compromise limiting ETOX (EPROM Tunnel Oxide) NOR flash alterability to large blocks of data instead of the single byte alterability of EEPROM. Based on EPROM technology, the ETOX process was relatively easy to develop and technological challenges were eventually overcome. But the bigger challenge was convincing Intel senior management to invest in ETOX flash when they desired the full function byte alterability of the EEPROM. Once the company was united behind ETOX flash, a large team effort involving multiple disciplines came together to build a fast‐growing flash memory business. Flash memory became a billion‐dollar business for Intel when ETOX NOR flash was adapted for code store in cellular phones. For 20 years, Intel maintained NOR flash technology and market leadership by developing and manufacturing 10 generations of ETOX technologies including multi‐level‐cell technologies that provided over a one thousand times cost reduction capability.