SONOS
SONOS, short for "Silicon-Oxide-Nitride-Oxide-Silicon", is a type of non-volatile computer memory closely related to Flash RAM. It is one of Charge trap flash variants. It is distinguished from mainstream flash by the use of silicon nitride (Si3N4) instead of polysilicon for the charge storage material. A further variant is "SHINOS" ("Silicon Hi-k Nitride Oxide Silicon"). SONOS promises lower programming voltages and higher program/erase cycle endurance than polysilicon-based flash, and is an area of active research and development effort. Companies offering SONOS-based products include GlobalFoundries, Cypress Semiconductor, Macronix, Toshiba, and United Microelectronics Corporation.