USRE34821E - High speed junction field effect transistor for use in bipolar integrated circuits - Google Patents
High speed junction field effect transistor for use in bipolar integrated circuits Download PDFInfo
- Publication number
- USRE34821E USRE34821E US08/036,935 US3693593A USRE34821E US RE34821 E USRE34821 E US RE34821E US 3693593 A US3693593 A US 3693593A US RE34821 E USRE34821 E US RE34821E
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- United States
- Prior art keywords
- layer
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- conductivity type
- field effect
- effect transistor
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- 230000005669 field effect Effects 0.000 title claims abstract description 10
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 14
- 229920005591 polysilicon Polymers 0.000 claims description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 6
- 229910052710 silicon Inorganic materials 0.000 claims description 6
- 239000010703 silicon Substances 0.000 claims description 6
- 239000000758 substrate Substances 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 4
- 239000004065 semiconductor Substances 0.000 claims description 4
- 238000002955 isolation Methods 0.000 claims description 2
- 210000000746 body region Anatomy 0.000 claims 6
- 229910052751 metal Inorganic materials 0.000 abstract description 8
- 239000002184 metal Substances 0.000 abstract description 8
- 239000002210 silicon-based material Substances 0.000 abstract description 2
- 239000010410 layer Substances 0.000 abstract 3
- 239000002344 surface layer Substances 0.000 abstract 2
- 229910052782 aluminium Inorganic materials 0.000 description 6
- 238000009792 diffusion process Methods 0.000 description 6
- 108091006146 Channels Proteins 0.000 description 4
- 239000002019 doping agent Substances 0.000 description 3
- 238000005468 ion implantation Methods 0.000 description 3
- 230000004888 barrier function Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 238000005382 thermal cycling Methods 0.000 description 2
- 108010075750 P-Type Calcium Channels Proteins 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- XUIMIQQOPSSXEZ-RNFDNDRNSA-N silicon-32 atom Chemical compound [32Si] XUIMIQQOPSSXEZ-RNFDNDRNSA-N 0.000 description 1
Images
Classifications
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
- H10D62/10—Shapes, relative sizes or dispositions of the regions of the semiconductor bodies; Shapes of the semiconductor bodies
- H10D62/17—Semiconductor regions connected to electrodes not carrying current to be rectified, amplified or switched, e.g. channel regions
- H10D62/343—Gate regions of field-effect devices having PN junction gates
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D30/00—Field-effect transistors [FET]
- H10D30/01—Manufacture or treatment
- H10D30/051—Manufacture or treatment of FETs having PN junction gates
- H10D30/0512—Manufacture or treatment of FETs having PN junction gates of FETs having PN homojunction gates
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D30/00—Field-effect transistors [FET]
- H10D30/80—FETs having rectifying junction gate electrodes
- H10D30/83—FETs having PN junction gate electrodes
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
- H10D62/80—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials
- H10D62/83—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials being Group IV materials, e.g. B-doped Si or undoped Ge
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10D64/00—Electrodes of devices having potential barriers
- H10D64/60—Electrodes characterised by their materials
- H10D64/62—Electrodes ohmically coupled to a semiconductor
Definitions
- This invention relates generally to semiconductor transistor devices, and more particularly to a high speed junction field effect transistor.
- JFETs junction field effect transistors
- BIFETs bipolar integrated circuits
- One such transistor is disclosed in U.S. Pat. No. 4,176,368.
- Operating speed is an important characteristic of such a transistor.
- BIFET structures have included top and bottom gates with the top gate comprising a lightly doped region above the transistor channel region and with the top and bottom gates electrically connected through the semiconductor structure.
- U.S. Pat. No. 4,176,368 proposes a higher speed BIFET by forming a more heavily doped region in the lightly doped top gate between and separated from the source and drain regions of the transistor. The heavily doped region reduces the gate conductance from 5-15 kilo-ohms per square to a range of 500-1500 ohms per square.
- JFETS having independent upper and lower gate contacts are known.
- the prior art teaches the use of barrier metals on the surface of the upper gate to prevent penetration of aluminum contacts into the underlying silicon material.
- Use of the barrier metal creates a thermal mismatch with the silicon leading to hysteresis effects during thermal cycling which degrade the device.
- This invention is directed to an improved higher speed BIFET.
- a highly doped polycrystalline silicon gate contact is formed on the surface of the thin, lightly doped top gate region extending between the source and drain regions.
- the ion implanted silicon gate contact is electrically separated from the bottom contact, thereby permitting a four-terminal device operation, if desired.
- a metal contact such as aluminum, for example, can be placed on the surface of the polysilicon layer to further reduce resistance.
- the polycrystalline layer inhibits punch through (diffusion) of the aluminum contact metal into the gate and channel regions by the aluminum contact.
- the lightly doped top gate layer beneath the polysilicon gate contact can be more heavily doped by diffusion from the highly doped polycrystalline layer to increase its conductivity.
- the gate resistance in accordance with this invention can be reduced to on the order of 1-40 ohms per square, as opposed to the 500-1500 ohms per square for the device disclosed in the '368 patent.
- the polycrystalline layer permits high temperature processing and the formation of thermal oxide on the surface of the layer.
- an object of the invention is to provide an improved silicon BIFET.
- Another object of the invention is to provide a BIFET having increased operating speed.
- a further object of this invention is to provide a BIFET which can be thermally cycled without degradation of device performance.
- FIG. 1 is a sectional view of a BIFET device in accordance with the prior art.
- FIG. 2 is a sectional view of another BIFET device in accordance with the prior art.
- FIG. 3 is a sectional view of a BIFET device in accordance with one embodiment of the invention.
- FIG. 4 is a sectional view in accordance with another embodiment of the invention.
- FIGS. 1 and 2 are sectional views of prior art BIFET devices as disclosed in U.S. Pat. No. 4,176,368.
- an N-type epitaxial layer 10 is formed on a surface of P-type silicon substrate 12 with a device region defined by P+ isolation diffusion ring 14.
- An N+ buried layer 16 is formed by doping a surface region of substrate 12 prior to the epitaxial growth of layer 10.
- a BIFET device is then formed in the epitaxial layer 10 with a source region 18 and a spaced drain region 20 formed by diffusion with P+ dopants.
- a gate contact 22 is formed by diffusion with N+ dopant.
- a P-type channel region 24 is formed by ion implantation between the source and drain region 18, 20, and a lightly doped top gate layer 26 is formed by ion implantation on the surface between the source and drain regions.
- the N-type top gate layer 26 is interconnected with the bottom gate contact defined by epitaxial layer 10 through the epitaxial structure.
- Metal contacts 28 are made to the source, drain and gate region.
- a high doped region 30 in the lightly doped top gate contact region 26 is formed by the selective introduction of N-type dopants by ion implantation, for example.
- the N+ region 30 is electrically interconnected with the bottom gate contact comprising epitaxial layer 10 through the epitaxial structure. Due to the increased conductance of N+ layer 30, the gate resistance is reduced from approximately 5-15 kilo-ohms per square with the device of FIG. 1 to 500-1500 ohms per square with the device of FIG. 2. The reduction in gate resistance results in a significant increase in operating speed.
- FIG. 3 is a sectional view of a silicon BIFET device in accordance with this invention. Again, like elements have the same reference numbers as in FIGS. 1 and 2.
- a highly doped polysilicon contact 32 is made to an intermediate portion of the lightly doped top layer 26, spaced from the source and drain region 18, 20.
- a highly doped region 30 is provided in the lightly doped gate layer 26 beneath the contact 32 as in the embodiment of FIG. 2.
- the increased speed of operation of the device of FIG. 3 depends primarily on the provision of the high conductance contact as described below, and only secondarily on the provision of the highly doped region 30. Thus, the provision of region 30 is not essential to the invention.
- the contact comprises a thin layer of highly doped polycrystalline silicon 32 and a metal layer 34 of aluminum, for example, provided on the top surface of contact 32, thereby further increasing the conductance of the contact and further increasing the speed of operation.
- the highly doped polysilicon layer 32 not only increases the conductance of the contact to the gate region 30, but also inhibits punch through of the aluminum contact during subsequent high temperature processing steps, and provides impurities which diffuse into the region 30 to increase its conductance.
- the polysilicon layer is thermally matched to the substrate, thereby minimizing degradation of the device during thermal cycling.
- the top gate contact is isolated from the bottom gate contact, thereby providing a four-terminal device.
- the smaller area of the top gate metal contact 34 reduces the parasitic capacitance and leakage current.
- FIG. 4 shows an embodiment of the invention without a high conductance region 30.
- the impurities from the polysilicon layer are not only allowed to diffuse into the underlying gate region 26, but also into the channel region as shown by the dotted line 36. This effectively reduces the thickness of the channel and increases the frequency of operation.
Landscapes
- Insulated Gate Type Field-Effect Transistor (AREA)
Abstract
Description
Claims (4)
- polysilicon layer..]. 3. A high speed junction field effect transistor comprisinga silicon semiconductor body region of one conductivity type,first and second regions of opposite conductivity type formed in a surface of said body region and spaced from each other, said first and second regions forming a source and a drain of said transistor,a thin channel region of said opposite conductivity type in said body region and interconnecting said first and second regions,a thin surface gate layer of said one conductivity type overlying said channel region and extending from said first region to said second region, anda surface contact on said surface gate .[.region.]. .Iadd.layer .Iaddend.between said first and second regions and electrically isolated from said body region, said surface contact comprising polycrystalline silicon layer of said one conductivity type and having a conductivity greater than the conductivity of said surface gate layer, said body region beneath said channel region and said surface contact comprising electrically separate gates for said transistor, said thin surface gate layer and an upper region of said channel region include impurities diffused thereinto from said polysilicon layer and
- an aluminum metal contact on said polycrystalline silicon layer. 4. The field effect transistor as in claim 3 wherein said semiconductor body region comprises an epitaxial layer, and further including a substrate of said opposite conductivity type on which said epitaxial layer is formed.
- The field effect transistor as in claim 4 and further including a buried layer of said .[.first.]. .Iadd.one .Iaddend.conductivity type formed in said substrate at the interface of said epitaxial layer and
- positioned beneath said first and second regions. 6. The field effect transistor as in claim 5 and further including an isolation region of said opposite conductivity type extending from the surface of said epitaxial layer to said substrate and surrounding said first and second regions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/036,935 USRE34821E (en) | 1986-11-17 | 1993-03-25 | High speed junction field effect transistor for use in bipolar integrated circuits |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US93126386A | 1986-11-17 | 1986-11-17 | |
| US07/553,181 US5012305A (en) | 1986-11-17 | 1990-07-13 | High speed junction field effect transistor for use in bipolar integrated circuits |
| US08/036,935 USRE34821E (en) | 1986-11-17 | 1993-03-25 | High speed junction field effect transistor for use in bipolar integrated circuits |
Related Parent Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US93126386A Continuation-In-Part | 1986-11-17 | 1986-11-17 | |
| US07/553,181 Reissue US5012305A (en) | 1986-11-17 | 1990-07-13 | High speed junction field effect transistor for use in bipolar integrated circuits |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| USRE34821E true USRE34821E (en) | 1995-01-03 |
Family
ID=46247883
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US08/036,935 Expired - Lifetime USRE34821E (en) | 1986-11-17 | 1993-03-25 | High speed junction field effect transistor for use in bipolar integrated circuits |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | USRE34821E (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6020608A (en) | 1997-01-27 | 2000-02-01 | Nikon Corporation | Junction-type field-effect transistor with improved impact-ionization resistance |
| US6346446B1 (en) * | 1998-06-01 | 2002-02-12 | Massachusetts Institute Of Technology | Methods of forming features of integrated circuits using modified buried layers |
Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB997996A (en) * | 1962-02-19 | 1965-07-14 | Motorola Inc | Field effect device and method of manufacturing the same |
| US3333115A (en) * | 1963-11-20 | 1967-07-25 | Toko Inc | Field-effect transistor having plural insulated-gate electrodes that vary space-charge voltage as a function of drain voltage |
| US3335342A (en) * | 1962-06-11 | 1967-08-08 | Fairchild Camera Instr Co | Field-effect transistors |
| US3538399A (en) * | 1968-05-15 | 1970-11-03 | Tektronix Inc | Pn junction gated field effect transistor having buried layer of low resistivity |
| US3656031A (en) * | 1970-12-14 | 1972-04-11 | Tektronix Inc | Low noise field effect transistor with channel having subsurface portion of high conductivity |
| US4176368A (en) * | 1978-10-10 | 1979-11-27 | National Semiconductor Corporation | Junction field effect transistor for use in integrated circuits |
| US4185291A (en) * | 1977-06-30 | 1980-01-22 | Matsushita Electric Industrial Co., Ltd. | Junction-type field effect transistor and method of making the same |
| US4187514A (en) * | 1976-11-09 | 1980-02-05 | Tokyo Shibaura Electric Co., Ltd. | Junction type field effect transistor |
| US4267012A (en) * | 1979-04-30 | 1981-05-12 | Fairchild Camera & Instrument Corp. | Process for patterning metal connections on a semiconductor structure by using a tungsten-titanium etch resistant layer |
| US4482907A (en) * | 1981-03-10 | 1984-11-13 | Thomson-Csf | Planar-type field-effect transistor having metallized-well electrodes and a method of fabrication of said transistor |
| US4546366A (en) * | 1978-04-24 | 1985-10-08 | Buchanan Bobby L | Polysilicon/silicon junction field effect transistors and integrated circuits (POSFET) |
| WO1986002203A1 (en) * | 1984-10-05 | 1986-04-10 | Analog Devices, Incorporated | Low-leakage jfet |
| US4985739A (en) * | 1984-10-05 | 1991-01-15 | Analog Devices, Incorporated | Low-leakage JFET |
-
1993
- 1993-03-25 US US08/036,935 patent/USRE34821E/en not_active Expired - Lifetime
Patent Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB997996A (en) * | 1962-02-19 | 1965-07-14 | Motorola Inc | Field effect device and method of manufacturing the same |
| US3335342A (en) * | 1962-06-11 | 1967-08-08 | Fairchild Camera Instr Co | Field-effect transistors |
| US3333115A (en) * | 1963-11-20 | 1967-07-25 | Toko Inc | Field-effect transistor having plural insulated-gate electrodes that vary space-charge voltage as a function of drain voltage |
| US3538399A (en) * | 1968-05-15 | 1970-11-03 | Tektronix Inc | Pn junction gated field effect transistor having buried layer of low resistivity |
| US3656031A (en) * | 1970-12-14 | 1972-04-11 | Tektronix Inc | Low noise field effect transistor with channel having subsurface portion of high conductivity |
| US4187514A (en) * | 1976-11-09 | 1980-02-05 | Tokyo Shibaura Electric Co., Ltd. | Junction type field effect transistor |
| US4185291A (en) * | 1977-06-30 | 1980-01-22 | Matsushita Electric Industrial Co., Ltd. | Junction-type field effect transistor and method of making the same |
| US4546366A (en) * | 1978-04-24 | 1985-10-08 | Buchanan Bobby L | Polysilicon/silicon junction field effect transistors and integrated circuits (POSFET) |
| US4176368A (en) * | 1978-10-10 | 1979-11-27 | National Semiconductor Corporation | Junction field effect transistor for use in integrated circuits |
| US4267012A (en) * | 1979-04-30 | 1981-05-12 | Fairchild Camera & Instrument Corp. | Process for patterning metal connections on a semiconductor structure by using a tungsten-titanium etch resistant layer |
| US4482907A (en) * | 1981-03-10 | 1984-11-13 | Thomson-Csf | Planar-type field-effect transistor having metallized-well electrodes and a method of fabrication of said transistor |
| WO1986002203A1 (en) * | 1984-10-05 | 1986-04-10 | Analog Devices, Incorporated | Low-leakage jfet |
| US4985739A (en) * | 1984-10-05 | 1991-01-15 | Analog Devices, Incorporated | Low-leakage JFET |
Non-Patent Citations (2)
| Title |
|---|
| IBM Technical Disclosure Bulletin, vol. 21, No. 7, pp. 2757 2758, Dec. 1978, by Anantha et al. * |
| IBM Technical Disclosure Bulletin, vol. 21, No. 7, pp. 2757-2758, Dec. 1978, by Anantha et al. |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6020608A (en) | 1997-01-27 | 2000-02-01 | Nikon Corporation | Junction-type field-effect transistor with improved impact-ionization resistance |
| US6346446B1 (en) * | 1998-06-01 | 2002-02-12 | Massachusetts Institute Of Technology | Methods of forming features of integrated circuits using modified buried layers |
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| AS | Assignment |
Owner name: LINEAR TECHNOLOGY LLC, CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LINEAR TECHNOLOGY CORPORATION;REEL/FRAME:058303/0255 Effective date: 20170502 Owner name: ANALOG DEVICES INTERNATIONAL UNLIMITED COMPANY, IRELAND Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LINEAR TECHNOLOGY LLC;REEL/FRAME:057888/0345 Effective date: 20181105 |