Flash memory: a challenged memory technology

Flash memory although being an evolutionary rather than revolutionary technology nevertheless revolutionized the entire memory business. While (electrically) erasable and programmable ROMs (EEPROMs and EPROMs) only served a minor application field, the combination of electrical erasability with high density - known today as flash memory - has changed the face of the memory business in an unprecedented way. Although the technology is constantly being challenged by new promising alternatives, there is still quite some momentum remaining for flash scaling provided the technology becomes more application-specific and more hierarchically integrated with other memories on the system level. This paper briefly reviews the basics of NOR and NAND technology as well as its embedded counterparts as being used today, the way they are linked to the application and system levels, as well as some alternative charge-based memories such as nanocrystal and nitride memory