WO1989006049A1 - Logic gate - Google Patents
Logic gate Download PDFInfo
- Publication number
- WO1989006049A1 WO1989006049A1 PCT/GB1988/001051 GB8801051W WO8906049A1 WO 1989006049 A1 WO1989006049 A1 WO 1989006049A1 GB 8801051 W GB8801051 W GB 8801051W WO 8906049 A1 WO8906049 A1 WO 8906049A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- region
- layer
- devices
- doped
- collector
- Prior art date
Links
- 238000002347 injection Methods 0.000 claims description 5
- 239000007924 injection Substances 0.000 claims description 5
- 239000000758 substrate Substances 0.000 claims description 5
- 210000000988 bone and bone Anatomy 0.000 claims description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 3
- 229910052814 silicon oxide Inorganic materials 0.000 claims 1
- 239000000463 material Substances 0.000 description 4
- 238000012856 packing Methods 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/02—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having potential barriers; including integrated passive circuit elements having potential barriers
- H01L27/0203—Particular design considerations for integrated circuits
- H01L27/0214—Particular design considerations for integrated circuits for internal polarisation, e.g. I2L
- H01L27/0229—Particular design considerations for integrated circuits for internal polarisation, e.g. I2L of bipolar structures
- H01L27/0233—Integrated injection logic structures [I2L]
Definitions
- This inventor relates to Integrated Injection Logic (P 2 L) gates.
- I 2 L gates are used extensively in integrated circuit logic and memory designs. It's popularity is due to its compatibility with bipolar transistor processes, relatively simple layout and reasonably high packing density.
- FIG. 1 of the accompanying drawings shows a circuit diagram and a schematic cross-section of a typical I 2 L gate.
- a buried N+ layer 10 acts as a base for a lateral pnp transistor Q 1 and as a common emitter for a vertical npn transistor Q 2 having a plurality of collectors.
- the collector of transistor Q 1 is an isolated P+ region 11 and the collectors of transistor Q2 are isolated N+ regions 12 in a P region 13 (which also acts as the collector of transistor Q 1 ).
- the injector, base and collector contacts are located in wells etched in an SIO 2 layer.
- Figures 2 (1 ), 2 (1 1 ) and 3 are schematic plan views of I 2 L devices of single collector, non-walled (figure 2 (1 )). single collector, walled contact areas (Figure 2 (11)) and multiple collector, non walled ( Figure 3) I 2 L devices known in the prior art. The contacts and doped areas of these devices are as indicated by the legend of Figure 2.
- a disadvantage of such devices is that collector fan out is limited due to the resistance of the P area forming the base of the transistor Q 2 .
- a fan out of three is possibly provided that the bases of the driven devices are substantially equidistant and the metal routes thereto are kept short.
- the device of figure 3 will thus support three devices for each collector. As the number of collectors is increased, however, the resistance R BB is high due to the P substrate. Thus a large P area also reduces gain and is a detrimental factor in the speed/power product.
- an integrated injection logic device comprising a substrate having a buried N+ layer, an isolated P+ layer and a common P region providing base and collector areas, and wherein the common P region is comb shaped and has its back bone and first tooth forming a base region doped to a P+ level and at least a further tooth doped to a P level with an overlying N+ layer forming a collector region.
- Figure 4 is a schematic plan view of an improved integrated injection logic gate in accordance with the present invention.
- Figure 5 is a diagrammatic plan view of an advantageous gate arrangement.
- an Integrated Injection Logic ( I 2 L) device in accordance with the present invention, comprises a substrate of a semiconductor material having a common buried N+ layer and an isolated P+ region 33 for the injector as in the prior art.
- the P layer of the prior art (See Figure 1) is replaced by a comb-shaped layer of P material produced by appropriate masking and doping.
- the back bone 37 and a first tooth 39 of the comb are masked and doped to a P+ level.
- a contact is made to the P+ layer constituting the first tooth 39 to provide a base 35 for the device.
- third and further teeth 41 of the comb are masked and doped to a P level, and, thereafter, are doped to provide superjacent N+ layers. Contacts are made to the N+ layers to form the collectors of the device .
- the contacts to the injector 33, the base 35 and the collectors 45 may be effected in respective wells etched in a top layer of S i O 2 on the substrate.
- the doping may be effected in such manner that the whole comb shaped structure is doped to P level and thereafter masked and further doped to the P+ level in the region of the back bone 37 and first tooth 39.
- the whole comb shaped structure may be doped to the P+ level, and thereafter, doping with the N+ material in the regions of the second and subsequent teeth 41 be effected to leave a subjacent P layer.
- gates have an injector for each base and collector or collectors.
- the layout is rearranged ( Figure 5 (1 )) so that the or each injector is common to a pair of bases and collectors.
- each injector 50 has a base 52 and a collector 54 at each side thereof.
- a chip area saving approaching 20% can thus be acheived.
- the invention is not confined to the precise details of the foregoing examples and variations may be made thereto. For instance, as conduction within the P+ layer is higher than that in a P layer, each collector may have a greater fan out with less restriction on the driven devices. Further, more collectors, per device, can be provided as the base resistance is reduced.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Bipolar Integrated Circuits (AREA)
Abstract
The invention provides an I2L device in which a P+ region forms a collector of the injector and further provides an extended connection to one or more P- regions forming the base of the virtual transistor or transistors of the device.
Description
LOGIC GATE
This inventor relates to Integrated Injection Logic (P2L) gates.
I2L gates are used extensively in integrated circuit logic and memory designs. It's popularity is due to its compatibility with bipolar transistor processes, relatively simple layout and reasonably high packing density.
Figure 1 of the accompanying drawings, shows a circuit diagram and a schematic cross-section of a typical I2L gate. A buried N+ layer 10 acts as a base for a lateral pnp transistor Q 1 and as a common emitter for a vertical npn transistor Q2 having a plurality of collectors. The collector of transistor Q1 is an isolated P+ region 11 and the collectors of transistor Q2 are isolated N+ regions 12 in a P region 13 (which also acts as the collector of transistor Q 1 ). The injector, base and collector contacts are located in wells etched in an SIO2 layer.
Figures 2 (1 ), 2 (1 1 ) and 3 are schematic plan views of I2L devices of single collector, non-walled (figure 2 (1 )). single collector, walled contact areas (Figure 2 (11)) and multiple collector, non walled (Figure 3) I2L devices known in the prior art. The contacts and doped areas of these devices are as indicated by the legend of Figure 2.
A disadvantage of such devices is that collector fan out is limited due to the resistance of the P area forming the base of the transistor Q2. A fan out of three is possibly provided that the bases of the driven devices are substantially equidistant and the metal routes thereto are kept short. The device of figure 3 will thus
support three devices for each collector. As the number of collectors is increased, however, the resistance RBB is high due to the P substrate. Thus a large P area also reduces gain and is a detrimental factor in the speed/power product.
It is an object of the present invention to provide an I2L gate wherein the aforesaid disadvantages are minimised.
According to the present invention, there is provided an integrated injection logic device comprising a substrate having a buried N+ layer, an isolated P+ layer and a common P region providing base and collector areas, and wherein the common P region is comb shaped and has its back bone and first tooth forming a base region doped to a P+ level and at least a further tooth doped to a P level with an overlying N+ layer forming a collector region.
The invention will be described further, by way of example, with reference to figures 4 and 5 of the accompanying drawings, in which:-
Figure 4 is a schematic plan view of an improved integrated injection logic gate in accordance with the present invention: and,
Figure 5 is a diagrammatic plan view of an advantageous gate arrangement.
Referring firstly to Figure 4, an Integrated Injection Logic ( I2L) device, in accordance with the present invention, comprises a substrate of a semiconductor material having a common buried N+ layer and an isolated P+ region 33 for the injector as in the prior art. In accordance with the present invention, the P layer of the prior art (See Figure 1) is replaced by a comb-shaped layer of P material produced by appropriate masking and doping. The back bone 37 and
a first tooth 39 of the comb are masked and doped to a P+ level. A contact is made to the P+ layer constituting the first tooth 39 to provide a base 35 for the device. Second, third and further teeth 41 of the comb are masked and doped to a P level, and, thereafter, are doped to provide superjacent N+ layers. Contacts are made to the N+ layers to form the collectors of the device . The contacts to the injector 33, the base 35 and the collectors 45 may be effected in respective wells etched in a top layer of SiO2 on the substrate.
It will be appreciated that the doping may be effected in such manner that the whole comb shaped structure is doped to P level and thereafter masked and further doped to the P+ level in the region of the back bone 37 and first tooth 39. Alternatively, the whole comb shaped structure may be doped to the P+ level, and thereafter, doping with the N+ material in the regions of the second and subsequent teeth 41 be effected to leave a subjacent P layer.
The arrangement shown in Figure 5 may, with advantage be applied to I2L gates in accordance with the present invention. It is however applicable to other semiconductive devices wherein it similarly provides a saving in overall chip area.
Conventionally, gates (Figures 5(1 )) have an injector for each base and collector or collectors. In accordance with this feature, the layout is rearranged (Figure 5 (1 )) so that the or each injector is common to a pair of bases and collectors.
As shown in Figure 5 (11 ), each injector 50 has a base 52 and a collector 54 at each side thereof. A chip area saving approaching 20% can thus be acheived.
The invention is not confined to the precise details of the foregoing examples and variations may be made thereto. For instance, as conduction within the P+ layer is higher than that in a P layer, each collector may have a greater fan out with less restriction on the driven devices. Further, more collectors, per device, can be provided as the base resistance is reduced.
As the area of P material is reduced, gain and speed/power product are increased.
Utilising the arrangement of Figure 5 (11), a greater packing density can be achieved for an integrated circuit employing so arranged devices.
Claims
1 . An integrated injection logic device comprising a substrate having a buried N+ layer, an isolated P+ layer and a common P region providing base and collector areas, and wherein the common P region is comb shaped and has its back bone and first tooth forming a base region doped to a P+ level and at least a further tooth doped to a P level with an overlying N+ layer forming a collector region.
2. A device as claimed in claim 1 comprising a plurality of further teeth each doped to a P level and each having a respective overlying N+ region to define respective collectors.
3. A device as claimed in claim 1 or 2 having a top layer of silicon oxide having wells etched therein in register with the P+ injector region, the P+ base region, and the N+ collector region or regions, and contacts to said regions in the wells.
4. An integrated circuit comprising a plurality of devices each as claimed in claim 1 and wherein an injector of a first of the devices constitutes also the injector of a second of the devices.
5. An integrated circuit comprising two devices as claimed in claim 1 wherein the doped area constituting the isolated P+ layer of one of said two devices acts as the isolated P+ layer of the other device.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8729417 | 1987-12-17 | ||
GB878729417A GB8729417D0 (en) | 1987-12-17 | 1987-12-17 | Logic gate |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1989006049A1 true WO1989006049A1 (en) | 1989-06-29 |
Family
ID=10628620
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1988/001051 WO1989006049A1 (en) | 1987-12-17 | 1988-12-01 | Logic gate |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0349622A1 (en) |
JP (1) | JPH04501341A (en) |
GB (1) | GB8729417D0 (en) |
WO (1) | WO1989006049A1 (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2316730A1 (en) * | 1975-06-19 | 1977-01-28 | Texas Instruments Inc | INTEGRATED LOGIC CIRCUIT AND ITS MANUFACTURING PROCESS |
US4081822A (en) * | 1975-06-30 | 1978-03-28 | Signetics Corporation | Threshold integrated injection logic |
EP0021403A1 (en) * | 1979-06-29 | 1981-01-07 | International Business Machines Corporation | Self-aligned semiconductor circuits |
-
1987
- 1987-12-17 GB GB878729417A patent/GB8729417D0/en active Pending
-
1988
- 1988-12-01 EP EP19890900278 patent/EP0349622A1/en not_active Withdrawn
- 1988-12-01 WO PCT/GB1988/001051 patent/WO1989006049A1/en not_active Application Discontinuation
- 1988-12-01 JP JP50094088A patent/JPH04501341A/en active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2316730A1 (en) * | 1975-06-19 | 1977-01-28 | Texas Instruments Inc | INTEGRATED LOGIC CIRCUIT AND ITS MANUFACTURING PROCESS |
US4081822A (en) * | 1975-06-30 | 1978-03-28 | Signetics Corporation | Threshold integrated injection logic |
EP0021403A1 (en) * | 1979-06-29 | 1981-01-07 | International Business Machines Corporation | Self-aligned semiconductor circuits |
Non-Patent Citations (2)
Title |
---|
IBM Technical Disclosure Bulletin, vol. 19, no. 6, November 1976 (New York, US) C.S. Chang et al.: "High-density, high-performance I2Lcell" pages 2084-2085 * |
IBM Technical Disclosure Bulletin, vol. 22, no. 7, December 1979 (New York, US) H.H. Berger et al.: "Double polysilicon MTL structure" pages 2786-2788 * |
Also Published As
Publication number | Publication date |
---|---|
JPH04501341A (en) | 1992-03-05 |
EP0349622A1 (en) | 1990-01-10 |
GB8729417D0 (en) | 1988-02-03 |
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