Diffused junction transistor: Difference between revisions
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{{Short description|Type of transistor}} |
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{{refimprove|date=February 2011}} |
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A '''diffused junction transistor''' is a transistor formed by diffusing [[dopant]]s into a [[semiconductor]] [[Wafer (electronics)|substrate]]. The diffusion process was developed later than the [[Alloy-junction transistor|alloy |
A '''diffused junction transistor''' is a [[transistor]] formed by diffusing [[dopant]]s into a [[semiconductor]] [[Wafer (electronics)|substrate]]. The diffusion process was developed later than the [[Alloy-junction transistor|alloy-junction]] and [[Grown-junction transistor|grown junction]] processes for making bipolar junction transistors (BJTs). |
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[[Bell Labs]] developed the first prototype diffused junction bipolar transistors in 1954.<ref>[http://semiconductormuseum.com/PhotoGallery/PhotoGallery_Prototype_DiffusedBase.htm |
[[Bell Labs]] developed the first prototype diffused junction bipolar transistors in 1954.<ref>[http://semiconductormuseum.com/PhotoGallery/PhotoGallery_Prototype_DiffusedBase.htm Bell Labs Prototype Diffused Base Triode], Transistor Museum, Historic Transistor Photo Gallery.</ref> |
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==Diffused-base transistor== |
==Diffused-base transistor== |
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The earliest diffused junction transistors were '''diffused-base transistors'''. These transistors still had alloy emitters and sometimes alloy collectors like the earlier alloy-junction transistors. Only the base was diffused into the substrate. Sometimes the substrate formed the collector, but in transistors like [[Philco]]'s [[micro-alloy diffused transistor]]s the substrate was the bulk of the base. |
The earliest diffused junction transistors were '''diffused-base transistors'''. These transistors still had alloy emitters and sometimes alloy collectors like the earlier alloy-junction transistors. Only the base was diffused into the substrate. Sometimes the substrate formed the collector, but in transistors like [[Philco]]'s [[micro-alloy diffused transistor]]s the substrate was the bulk of the base. |
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==Double diffusion== |
==Double diffusion== |
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|isbn=9780262014243 |
|isbn=9780262014243 |
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|url=https://books.google.com/books?id=LaZpUpkG70QC |
|url=https://books.google.com/books?id=LaZpUpkG70QC |
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|ref=harv |
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}}, p. 11.</ref> |
}}, p. 11.</ref> |
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The diffused silicon '''mesa transistor''' was developed at [[Bell Labs]] in 1955 and made commercially available by [[Fairchild Semiconductor]] in 1958.<ref>{{Harvnb|Lécuyer|Brock|2010|pp=10–22}}</ref> |
The diffused silicon '''mesa transistor''' was developed at [[Bell Labs]] in 1955 and made commercially available by [[Fairchild Semiconductor]] in 1958.<ref>{{Harvnb|Lécuyer|Brock|2010|pp=10–22}}</ref> |
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These transistors were the first to have both diffused bases and diffused emitters. Unfortunately, like all earlier transistors, the edge of the collector–base junction was exposed, making it sensitive to leakage through surface contamination, thus requiring [[hermetic seal]]s or [[Passivation (chemistry)|passivation]] to prevent degradation of the transistor's characteristics over time.<ref>{{cite web |url=http://spectrum.ieee.org/semiconductors/design/the-silicon-dioxide-solution |title=The Silicon Dioxide Solution: How physicist Jean Hoerni built the bridge from the transistor to the integrated circuit |first=Michael |last=Riordan |work=IEEE Spectrum |date=December 2007 | |
These transistors were the first to have both diffused bases and diffused emitters. Unfortunately, like all earlier transistors, the edge of the collector–base junction was exposed, making it sensitive to leakage through surface contamination, thus requiring [[hermetic seal]]s or [[Passivation (chemistry)|passivation]] to prevent degradation of the transistor's characteristics over time.<ref>{{cite web |url=https://spectrum.ieee.org/semiconductors/design/the-silicon-dioxide-solution |archive-url=https://web.archive.org/web/20110215031520/http://spectrum.ieee.org/semiconductors/design/the-silicon-dioxide-solution |url-status=dead |archive-date=February 15, 2011 |title=The Silicon Dioxide Solution: How physicist Jean Hoerni built the bridge from the transistor to the integrated circuit|author1-link=Michael Riordan (physicist) |first=Michael |last=Riordan |work=IEEE Spectrum |date=December 2007 |access-date=November 28, 2012 |publisher=IEEE}}</ref> |
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==Planar transistor== |
==Planar transistor== |
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Planar transistors have a silica [[passivation (chemistry)|passivation]] layer to protect the junction edges from contamination, making inexpensive plastic packaging possible without risking degradation of the transistor's characteristics over time. |
Planar transistors have a silica [[passivation (chemistry)|passivation]] layer to protect the junction edges from contamination, making inexpensive plastic packaging possible without risking degradation of the transistor's characteristics over time. |
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The first planar transistors had a switching speed much lower than [[alloy junction transistor]]s of the period, but as they could be mass-produced, and alloy junction transistors could not, they cost much less, and the characteristics of planar transistors improved very rapidly, quickly exceeding those of all earlier transistors and making earlier transistors obsolete. |
The first planar transistors had a switching speed much lower than [[alloy junction transistor]]s of the period, but as they could be mass-produced, and alloy junction transistors could not, they cost much less, and the characteristics of planar transistors improved very rapidly, quickly exceeding those of all earlier transistors and making earlier transistors obsolete. |
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==References== |
==References== |
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{{reflist}} |
{{reflist}} |
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* F.M. Smits editor (1985) ''A History of Engineering and Science in the Bell System'', volume 6: Electronics Technology, pp 43–57, [[Bell Labs]], {{ISBN|0-932764-07-X}} . |
* F.M. Smits editor (1985) ''A History of Engineering and Science in the Bell System'', volume 6: Electronics Technology, pp 43–57, [[Bell Labs]], {{ISBN|0-932764-07-X}} . |
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{{Electronic components}} |
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[[Category:Transistor types]] |
[[Category:Transistor types]] |
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Latest revision as of 03:26, 31 July 2024
 | This article needs additional citations for verification. (February 2011) |
A diffused junction transistor is a transistor formed by diffusing dopants into a semiconductor substrate. The diffusion process was developed later than the alloy-junction and grown junction processes for making bipolar junction transistors (BJTs).
Bell Labs developed the first prototype diffused junction bipolar transistors in 1954.[1]
Diffused-base transistor
[edit]The earliest diffused junction transistors were diffused-base transistors. These transistors still had alloy emitters and sometimes alloy collectors like the earlier alloy-junction transistors. Only the base was diffused into the substrate. Sometimes the substrate formed the collector, but in transistors like Philco's micro-alloy diffused transistors the substrate was the bulk of the base.
Double diffusion
[edit]At Bell Labs Calvin Souther Fuller produced basic physical understanding of a means of directly forming the emitter, base, and collector by double diffusion. The method was summarized in a history of science at Bell:[2]
- "Fuller had shown that acceptors of low atomic weight diffuse more rapidly than donors, which made possible n–p–n structures by simultaneous diffusion of donors and acceptors of appropriately different surface concentrations. The first n layer (the emitter) was formed because of the greater surface concentration of the donor (for example, antimony). The base formed beyond it because of the more rapid diffusion of the acceptor (for example, aluminum). The inner (collector) boundary of the base appeared where the diffused aluminum no longer over-compensated the n-type background doping of the original silicon. The base layers of the resulting transistors were 4 μm thick. ... Resulting transistors had a cut-off frequency of 120 MHz."
Mesa transistor
[edit]
Texas Instruments made the first grown-junction silicon transistors in 1954.[3] The diffused silicon mesa transistor was developed at Bell Labs in 1955 and made commercially available by Fairchild Semiconductor in 1958.[4]
These transistors were the first to have both diffused bases and diffused emitters. Unfortunately, like all earlier transistors, the edge of the collector–base junction was exposed, making it sensitive to leakage through surface contamination, thus requiring hermetic seals or passivation to prevent degradation of the transistor's characteristics over time.[5]
Planar transistor
[edit]
The planar transistor was developed by Dr. Jean Hoerni[6] at Fairchild Semiconductor in 1959. The planar process used to make these transistors made mass-produced monolithic integrated circuits possible.
Planar transistors have a silica passivation layer to protect the junction edges from contamination, making inexpensive plastic packaging possible without risking degradation of the transistor's characteristics over time.
The first planar transistors had a switching speed much lower than alloy junction transistors of the period, but as they could be mass-produced, and alloy junction transistors could not, they cost much less, and the characteristics of planar transistors improved very rapidly, quickly exceeding those of all earlier transistors and making earlier transistors obsolete.
References
[edit]- ^ Bell Labs Prototype Diffused Base Triode, Transistor Museum, Historic Transistor Photo Gallery.
- ^ S. Millman editor (1983) A History of Engineering and Science in the Bell System, volume 4: Physical Sciences, Bell Labs ISBN 0-932764-03-7 p. 426
- ^ Lécuyer, Christophe; Brock, David C. (2010). Makers of the Microchip: A Documentary History of Fairchild Semiconductor. MIT Press. ISBN 9780262014243., p. 11.
- ^ Lécuyer & Brock 2010, pp. 10–22
- ^ Riordan, Michael (December 2007). "The Silicon Dioxide Solution: How physicist Jean Hoerni built the bridge from the transistor to the integrated circuit". IEEE Spectrum. IEEE. Archived from the original on February 15, 2011. Retrieved November 28, 2012.
- ^ Fairchild 2N1613, Transistor Museum, Historic Transistor Photo Gallery.
- F.M. Smits editor (1985) A History of Engineering and Science in the Bell System, volume 6: Electronics Technology, pp 43–57, Bell Labs, ISBN 0-932764-07-X .