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A VMOS ( /ˈviːmɒs/) (vertical metal oxide semiconductor or V-groove MOS) transistor is a type of metal–oxide–semiconductor field-effect transistor ( MOSFET). VMOS is also used to describe the V-groove shape vertically cut into the substrate material. [1]
The "V" shape of the MOSFET's gate allows the device to deliver a higher amount of current from the source to the drain of the device. The shape of the depletion region creates a wider channel, allowing more current to flow through it.
During operation in blocking mode, the highest electric field occurs at the N+/p+ junction. The presence of a sharp corner at the bottom of the groove enhances the electric field at the edge of the channel in the depletion region, thus reducing the breakdown voltage of the device. [2] This electric field launches electrons into the gate oxide and consequently, the trapped electrons shift the threshold voltage of the MOSFET. For this reason, the V-groove architecture is no longer used in commercial devices.
The device's use was a power device until more suitable geometries, like the UMOS (or Trench-Gate MOS) were introduced in order to lower the maximum electric field at the top of the V shape and thus leading to higher maximum voltages than in case of the VMOS.
History
The first MOSFET (without a V-groove) was invented by Mohamed Atalla and Dawon Kahng at Bell Labs in 1959. [3] The V-groove construction was pioneered by Jun-ichi Nishizawa in 1969, [4] initially for the static induction transistor (SIT), a type of junction field-effect transistor ( JFET). [5]
The VMOS was invented by Hitachi in 1969, [6] when they introduced the first vertical power MOSFET in Japan. [7] T. J. Rodgers, while he was a student at Stanford University, filed a US patent for a VMOS in 1973. [8] Siliconix commercially introduced a VMOS in 1975. [6] The VMOS later developed into what became known as the vertical DMOS ( VDMOS). [9]
In 1978, American Microsystems (AMI) released the S2811. [10] [11] It was the first integrated circuit chip specifically designed as a digital signal processor (DSP), and was fabricated using VMOS, a technology that had previously not been mass-produced. [11]
References
- ^ Holmes, F.E.; Salama, C.A.T. (1974). "VMOS—A new MOS integrated circuit technology". Solid-State Electronics. 17 (8): 791–797. Bibcode: 1974SSEle..17..791H. doi: 10.1016/0038-1101(74)90026-4.
- ^ Baliga, B. Jayant (2008), "Power MOSFETs", Fundamentals of Power Semiconductor Devices, Springer US, pp. 276–503, doi: 10.1007/978-0-387-47314-7_6, ISBN 9780387473130
- ^ "Rethink Power Density with GaN". Electronic Design. 21 April 2017. Retrieved 23 July 2019.
- ^ Duncan, Ben (1996). High Performance Audio Power Amplifiers. Elsevier. pp. 178 & 406. ISBN 9780080508047.
- ^ U.S. patent 4,295,267
- ^ a b "Advances in Discrete Semiconductors March On". Power Electronics Technology. Informa: 52–6. September 2005. Archived (PDF) from the original on 22 March 2006. Retrieved 31 July 2019.
- ^ Oxner, E. S. (1988). Fet Technology and Application. CRC Press. p. 18. ISBN 9780824780500.
- ^ U.S. patent 3,924,265
- ^ Duncan, Ben (1996). High Performance Audio Power Amplifiers. Elsevier. pp. 177-8, 406. ISBN 9780080508047.
- ^ "1979: Single Chip Digital Signal Processor Introduced". The Silicon Engine. Computer History Museum. Retrieved 14 October 2019.
- ^ a b Taranovich, Steve (August 27, 2012). "30 years of DSP: From a child's toy to 4G and beyond". EDN. Retrieved 14 October 2019.
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