Metal–nitride–oxide–semiconductor transistor explained

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-volatile computer memory.^[4]

History

The original MOSFET (metal–oxide–semiconductor field-effect transistor, or MOS transistor) was invented by Egyptian engineer Mohamed M. Atalla and Korean engineer Dawon Kahng at Bell Labs in 1959, and demonstrated in 1960.^[5] Kahng went on to invent the floating-gate MOSFET with Simon Min Sze at Bell Labs, and they proposed its use as a floating-gate (FG) memory cell, in 1967.^[6] This was the first form of non-volatile memory based on the injection and storage of charges in a floating-gate MOSFET,^[7] which later became the basis for EPROM (erasable PROM), EEPROM (electrically erasable PROM) and flash memory technologies.^[8]

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]

See also

• Field-effect transistor
• MISFET
• MOSFET
• SONOS

Notes and References

1. Book: Brodie . Ivor . Muray . Julius J. . The Physics of Microfabrication . 2013 . . 9781489921604 . 74 .
2. Frohman-Bentchkowsky. D.. The metal-nitride-oxide-silicon (MNOS) transistor—Characteristics and applications. Proceedings of the IEEE. 1970. 58. 8. 1207–1219. 10.1109/PROC.1970.7897.
3. Web site: Metal–nitride–oxide–semiconductor (MNOS) technology. JEDEC.
4. Book: Ng. Kwok K.. Complete Guide to Semiconductor Devices. John Wiley & Sons, Inc.. 9781118014769. 353–360. en. Metal-Nitride-Oxide Semiconductor Transistor. 10.1002/9781118014769.ch47. 2010.
5. 1960 - Metal Oxide Semiconductor (MOS) Transistor Demonstrated. The Silicon Engine. Computer History Museum.
6. Kahng . Dawon . Dawon Kahng . Sze . Simon Min . Simon Sze . A floating gate and its application to memory devices . . JulyAugust 1967 . 46 . 6 . 1288–1295 . 10.1002/j.1538-7305.1967.tb01738.x. 1967ITED...14Q.629K .
7. Book: Ioannou-Soufleridis . V. . Dimitrakis . Panagiotis . Normand . Pascal . Chapter 3: Charge-Trap Memories with Ion Beam Modified ONO Stracks . Charge-Trapping Non-Volatile Memories: Volume 1 – Basic and Advanced Devices . 2015 . Springer . 9783319152905 . 65–102 (65) . https://books.google.com/books?id=7vFUCgAAQBAJ&pg=PA65.
8. News: Not just a flash in the pan . . March 11, 2006 . 10 September 2019.
9. Wegener. H. A. R.. Lincoln. A. J.. Pao. H. C.. O'Connell. M. R.. Oleksiak. R. E.. Lawrence. H.. The variable threshold transistor, a new electrically-alterable, non-destructive read-only storage device. 1967 International Electron Devices Meeting. October 1967. 13. 70. 10.1109/IEDM.1967.187833.
10. Book: Prall . Kirk . Ramaswamy . Nirmal . Goda . Akira . Chapter 2: A Synopsis on the State of the Art of NAND Memories . Charge-Trapping Non-Volatile Memories: Volume 1 – Basic and Advanced Devices . 2015 . Springer . 9783319152905 . 37–64 (39) . https://books.google.com/books?id=7vFUCgAAQBAJ&pg=PA39.