The metal–nitride–oxide–semiconductor or metal–nitride–oxide–silicon (MNOS) transistor is a type of
MOSFET (metal–oxide–semiconductor field-effect transistor) in which the
oxide layer is replaced by a double layer of
nitride and oxide.[1] It is an alternative and supplement to the existing standard
MOS technology, wherein the insulation employed is a nitride-oxide layer.[2][3] It is used in
non-volatilecomputer memory.[4]
In late 1967, a
Sperry research team led by H.A. Richard Wegener invented the metal–nitride–oxide–semiconductor (MNOS) transistor,[9] a type of MOSFET in which the
oxide layer is replaced by a double layer of
nitride and oxide.[1]Nitride was used as a trapping layer instead of a floating gate, but its use was limited as it was considered inferior to a floating gate.[10]
Charge trap (CT) memory was introduced with MNOS devices in the late 1960s. It had a device structure and operating principles similar to floating-gate (FG) memory, but the main difference is that the charges are stored in a conducting material (typically a doped
polysilicon layer) in FG memory, whereas CT memory stored charges in localized traps within a
dielectric layer (typically made of
silicon nitride).[7]
^Frohman-Bentchkowsky, D. (1970). "The metal-nitride-oxide-silicon (MNOS) transistor—Characteristics and applications". Proceedings of the IEEE. 58 (8): 1207–1219.
doi:
10.1109/PROC.1970.7897.
^Ng, Kwok K. (2010). "Metal-Nitride-Oxide Semiconductor Transistor". Complete Guide to Semiconductor Devices. John Wiley & Sons, Inc. pp. 353–360.
doi:
10.1002/9781118014769.ch47.
ISBN9781118014769.
^Wegener, H. A. R.; Lincoln, A. J.; Pao, H. C.; O'Connell, M. R.; Oleksiak, R. E.; Lawrence, H. (October 1967). The variable threshold transistor, a new electrically-alterable, non-destructive read-only storage device. 1967 International Electron Devices Meeting. Vol. 13. p. 70.
doi:
10.1109/IEDM.1967.187833.