A VMOS () transistor is a type of MOSFET (metal-oxide-semiconductor field-effect transistor). VMOS is also used for describing the V-groove shape vertically cut into the substrate material. ''VMOS'' is an acronym for "vertical metal oxide semiconductor", or "V-groove MOS". The "V" shape of the MOSFET's

gate A gate or gateway is a point of entry to or from a space enclosed by walls. The word derived from old Norse "gat" meaning road or path; But other terms include ''yett and port''. The concept originally referred to the gap or hole in the wall ...

allows the device to deliver a higher amount of

current Currents, Current or The Current may refer to: Science and technology * Current (fluid), the flow of a liquid or a gas ** Air current, a flow of air ** Ocean current, a current in the ocean *** Rip current, a kind of water current ** Current (stre ...

from the

source Source may refer to: Research * Historical document * Historical source * Source (intelligence) or sub source, typically a confidential provider of non open-source intelligence * Source (journalism), a person, publication, publishing institute o ...

to the

drain Drain may refer to: Objects and processes * Drain (plumbing), a fixture that provides an exit-point for waste water or for water that is to be re-circulated on the side of a road * Drain (surgery), a tube used to remove pus or other fluids from ...

of the device. The shape of the

depletion region In semiconductor physics, the depletion region, also called depletion layer, depletion zone, junction region, space charge region or space charge layer, is an insulating region within a conductive, doped semiconductor material where the mobile ...

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. 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 A power semiconductor device is a semiconductor device used as a switch or rectifier in power electronics (for example in a switch-mode power supply). Such a device is also called a power device or, when used in an integrated circuit, a power IC. ...

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 Dawon Kahng ( ko, 강대원; May 4, 1931 – May 13, 1992) was a Korean-American electrical engineer and inventor, known for his work in solid-state electronics. He is best known for inventing the MOSFET (metal–oxide–semiconductor field-effe ...

Bell Labs Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial Research and development, research and scientific developm ...

in 1959. The V-groove construction was pioneered by

Jun-ichi Nishizawa was a Japanese engineer and inventor. He is known for his electronic inventions since the 1950s, including the PIN diode, static induction transistor, static induction thyristor, SIT/SITh. His inventions contributed to the development of ...

in 1969, initially for the static induction transistor (SIT), a type of

JFET The junction-gate field-effect transistor (JFET) is one of the simplest types of field-effect transistor. JFETs are three-terminal semiconductor devices that can be used as electronically controlled switches or resistors, or to build amplifier ...

(junction

field-effect transistor The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs ( JFETs or MOSFETs) are devices with three terminals: ''source'', ''gate'', and ''drain''. FETs cont ...

). The VMOS was invented by Hitachi in 1969, when they introduced the first vertical power MOSFET in Japan. T. J. Rodgers, while he was a student at Stanford University, filed a

US patent Under United States law, a patent is a right granted to the inventor of a (1) process, machine, article of manufacture, or composition of matter, (2) that is new, useful, and non-obvious. A patent is the right to exclude others, for a limited ...

for a VMOS in 1973. Siliconix commercially introduced a VMOS in 1975. The VMOS later developed into what became known as the

VDMOS A power MOSFET is a specific type of metal–oxide–semiconductor field-effect transistor (MOSFET) designed to handle significant power levels. Compared to the other power semiconductor devices, such as an insulated-gate bipolar transistor (IG ...

(vertical DMOS). In 1978, American Microsystems (AMI) released the S2811. 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.

References

Transistor types MOSFETs Japanese inventions {{Technology-stub