VMOS
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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.cite-ref-2[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.
Contents
• History
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History
The MOSFET was invented at Bell Labs between 1955 and 1960.cite-ref-0-3-0[3]cite-ref-4[4]cite-ref-5[5]cite-ref-6[6]cite-ref-7[7]cite-ref-lojek1202-8-0[8] The V-groove construction was pioneered by Jun-ichi Nishizawa in 1969,cite-ref-9[9] initially for the static induction transistor (SIT), a type of junction field-effect transistor (JFET).cite-ref-10[10]
The VMOS was invented by Hitachi in 1969,cite-ref-powerelectronics-11-0[11] when they introduced the first vertical power MOSFET in Japan.cite-ref-12[12] T. J. Rodgers, while he was a student at Stanford University, filed a US patent for a VMOS in 1973.cite-ref-13[13] Siliconix commercially introduced a VMOS in 1975.cite-ref-powerelectronics-11-1[11] The VMOS later developed into what became known as the vertical DMOS (VDMOS).cite-ref-duncan177-14-0[14]
In 1978, American Microsystems (AMI) released the S2811.cite-ref-computerhistory1979-15-0[15]cite-ref-edn-16-0[16] 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.cite-ref-edn-16-1[16]
References
cite-note-lojek1202-88. ↑ citereflojek2007Lojek, Bo (2007). History of Semiconductor Engineering. Springer Science & Business Media. p. 120. ISBN 9783540342588.
cite-note-1010. ↑ U.S. patent 4,295,267
cite-note-1313. ↑ U.S. patent 3,924,265
cite-note-computerhistory1979-1515. ↑ "1979: Single Chip Digital Signal Processor Introduced". The Silicon Engine. Computer History Museum. Retrieved 14 October 2019.