VMOS
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File:VMOS cross section en.png
A VMOS ({{IPAc-en|ˈ|v|iː|m|ɒ|s}}) (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.{{cite journal |last1=Holmes |first1=F.E. |last2=Salama |first2=C.A.T. |year=1974 |doi=10.1016/0038-1101(74)90026-4 |volume=17 |issue=8 |title=VMOS—A new MOS integrated circuit technology |journal=Solid-State Electronics |pages=791–797 |bibcode=1974SSEle..17..791H}}
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.{{Citation |last=Baliga |first=B. Jayant |chapter=Power MOSFETs |date=2008 |title=Fundamentals of Power Semiconductor Devices |pages=276–503 |publisher=Springer US |isbn=9780387473130 |doi=10.1007/978-0-387-47314-7_6}} 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 MOSFET was invented at Bell Labs between 1955 and 1960.{{Cite journal |last1=Huff |first1=Howard |last2=Riordan |first2=Michael |date=2007-09-01 |title=Frosch and Derick: Fifty Years Later (Foreword) |url=https://iopscience.iop.org/article/10.1149/2.F02073IF |journal=The Electrochemical Society Interface |volume=16 |issue=3 |pages=29 |doi=10.1149/2.F02073IF |issn=1064-8208|url-access=subscription }}{{Cite journal |last1=Frosch |first1=C. J. |last2=Derick |first2=L |date=1957 |title=Surface Protection and Selective Masking during Diffusion in Silicon |url=https://iopscience.iop.org/article/10.1149/1.2428650 |journal=Journal of the Electrochemical Society |language=en |volume=104 |issue=9 |pages=547 |doi=10.1149/1.2428650|url-access=subscription }}{{Cite journal |last=KAHNG |first=D. |date=1961 |title=Silicon-Silicon Dioxide Surface Device |url=https://doi.org/10.1142/9789814503464_0076 |journal=Technical Memorandum of Bell Laboratories|pages=583–596 |doi=10.1142/9789814503464_0076 |isbn=978-981-02-0209-5 |url-access=subscription }}{{Cite book |last=Lojek |first=Bo |title=History of Semiconductor Engineering |date=2007 |publisher=Springer-Verlag Berlin Heidelberg |isbn=978-3-540-34258-8 |location=Berlin, Heidelberg |page=321}}{{Cite journal |last1=Ligenza |first1=J.R. |last2=Spitzer |first2=W.G. |date=1960 |title=The mechanisms for silicon oxidation in steam and oxygen |url=https://linkinghub.elsevier.com/retrieve/pii/0022369760902195 |journal=Journal of Physics and Chemistry of Solids |language=en |volume=14 |pages=131–136 |doi=10.1016/0022-3697(60)90219-5|bibcode=1960JPCS...14..131L |url-access=subscription }}{{cite book |last1=Lojek |first1=Bo |title=History of Semiconductor Engineering |date=2007 |publisher=Springer Science & Business Media |isbn=9783540342588 |page=120}} The V-groove construction was pioneered by Jun-ichi Nishizawa in 1969,{{cite book |last1=Duncan |first1=Ben |title=High Performance Audio Power Amplifiers |date=1996 |publisher=Elsevier |isbn=9780080508047 |pages=[https://archive.org/details/highperfomanceau0000dunc/page/178 178 & 406] |url=https://archive.org/details/highperfomanceau0000dunc/page/178}} initially for the static induction transistor (SIT), a type of junction field-effect transistor (JFET).{{US patent|4295267}}
The VMOS was invented by Hitachi in 1969,{{cite journal |title=Advances in Discrete Semiconductors March On |url=https://www.powerelectronics.com/content/advances-discrete-semiconductors-march |journal=Power Electronics Technology |publisher=Informa |pages=52–6 |access-date=31 July 2019 |date=September 2005 |archive-url=https://web.archive.org/web/20060322222716/http://powerelectronics.com/mag/509PET26.pdf |archive-date=22 March 2006 |url-status=live}} when they introduced the first vertical power MOSFET in Japan.{{cite book |last1=Oxner |first1=E. S. |title=Fet Technology and Application |date=1988 |publisher=CRC Press |isbn=9780824780500 |page=18 |url=https://books.google.com/books?id=0AE-0e-sAnsC&pg=PA18}} T. J. Rodgers, while he was a student at Stanford University, filed a US patent for a VMOS in 1973.{{US patent|3924265}} Siliconix commercially introduced a VMOS in 1975. The VMOS later developed into what became known as the vertical DMOS (VDMOS).{{cite book |last1=Duncan |first1=Ben |title=High Performance Audio Power Amplifiers |date=1996 |publisher=Elsevier |isbn=9780080508047 |pages=[https://archive.org/details/highperfomanceau0000dunc/page/177 177-8, 406] |url=https://archive.org/details/highperfomanceau0000dunc/page/177}}
In 1978, American Microsystems (AMI) released the S2811.{{cite web |title=1979: Single Chip Digital Signal Processor Introduced |url=https://www.computerhistory.org/siliconengine/single-chip-digital-signal-processor-introduced/ |website=The Silicon Engine |publisher=Computer History Museum |access-date=14 October 2019}}{{cite web |last1=Taranovich |first1=Steve |title=30 years of DSP: From a child's toy to 4G and beyond |url=https://www.edn.com/design/systems-design/4394792/30-years-of-DSP--From-a-child-s-toy-to-4G-and-beyond |website=EDN |access-date=14 October 2019 |date=August 27, 2012}} 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
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