Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
  • H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
  • H01L23/528—Geometry or layout of the interconnection structure
  • H01L23/5283—Cross-sectional geometry
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

• This invention relates to semiconductor integrated circuits and more particularly to schemes for the interconnection of MOS (metal oxide semiconductor) devices therein, such as three level interconnection schemes with a single level of polysilicon stripes and two levels of metal stripes.
• MOS metal oxide semiconductor
• MOS metal oxide semiconductor
• second and third levels of interconnections in which at various points there are windows that are filled with metal (plugs) to connect third level stripes with second level stripes.
• the third level interconnections serve 5 especially to relieve crowding on the first level and to supply relatively low resistance interconnections across relatively long distances across the chip.
• the resulting scheme of three level interconnections (one level of polysilicon stripes plus two levels of metal
• This invention involves a semiconductor integrated circuit which has a region thereof comprising two or more mutually parallel and spaced apart elongated cell rows, all running parallel to a given direction in each of which is located a separate plurality of transistors--typically, MOS transistors—integrated at a major surface of a semiconductor body, such transistors being i terconnected and accessed by three levels of interconnection stripes, the first level consisting essentially of stripes for electrically connecting the control electrodes of the transistors to the rest of the circuit, the second level consisting essentially of stripes running perpendicular to the given direction of the elongated rows, and the third level consisting essentially of stripes running parallel to the given direction, in this way the first level stripes, typically polysilicon (doped with suitable impurities) which may or may not be overlaid with metal suicide, can be confined to cell row areas, and more importantly all the ends (terminations) of every first level stripe are confined to a single cell row area: in other words, no contact between first and second
• FIG. 1 is a top view diagram of a region of a semiconductor integrated circuit with three level i terconnections in accordance with an illustrative embodiment of the invention
• FIG. 2 is an equivalent logic diagram of the circuitry of the region shown in FIG. 1;
• FIG. 3 is a top view diagram of another region of a semiconductor integrated circuit with three level 5 interconnections in accordance with another illustrative embodiment of the invention.
• FIG. 4 is a side view in cross section of an indicated portion of FIG. 1.
• connections between second level stripes and the top surface of the underlying semiconductor body are indicated simply by (unencircled) dots; and connections between second and third level stripes are indicated by crosses. Arrows indicate the directions of propagation
• a region 5 of a silicon chip basically comprises a first pair of third level, parallel VDD and VSS power line stripes 11 and 12,
• All transistors that are integrated in the upper half of each cell row are PMOS (p-channel) ; all in the lower half therof are NMOS (n-channel) . As known in the CMOS integrated circuit art, all transistors located in the
• Input signals INI, IN2, and IN3 are brought into the region 5 along third level stripes 91, 92, and 93, respectively, and the output signal OUT of the region 5 is brought out along second level stripe 160, as well as third level stripes 161 and 162.
• the input signal INI passes successively through four inverters 125, 130, 60, 70 and then is fed through a second level interconnection stripe 181 as one of three inputs Al, IN2, and IN3 to a three-input NAND gate 140; whereas the input signals IN2 and IN3 are fed directly through second level interconnection stripes 182 and 183, respectively, to this same NAND gate 140 (See, also, FIG. 2) .
• the third level stripe 91 contacts a second level stripe 111 which, in turn, contacts a pair of first level stripes 112 and 117.
• the first level stripe 112 extends as a gate electrode over a PMOS transistor whose source region 113 is connected through a second level stripe 114 to the VDD power line 110 and whose drain region 115 is connected to a second level stripe 116.
• the first level stripe 117 extends as a gate electrode over an NMOS transistor whose source region 119 is connected through a second level stripe 121 to the VSS power line 120 and whose drain region 118 is contacted by the second level stripe 116.
• This second level stripe 116 is also connected to a third level stripe 122 which carries the output of the inverter 125.
• the source and drain regions 113 and 115, respectively, are both p-type silicon semiconductor and the source and drain regions 119 and 118 respectively, are both n-type silicon semiconductor, as known in the 5 art of CMOS integrated circuit technology.
• the third level stripe 122 is also connected, at its right-hand extremity, to a second level stripe 131 which delivers input for the inverter 130 much in the same manner as the second level stripe 111
• the second level stripe 51 contacts a pair of
• inverter 60 is delivered along a third level stripe 63 to another inverter 70 in similar manner as previously described in conjunction with the inverter 130.
• output of the inverter 70 is delivered as an input signal Al to the NAND gate 140 through the path formed
• third level stripe 71 a second level stripe 72, another third level stripe 73, and another second level stripe 181 to the three-input NAND gate 140.
• the NAND gate 140 is composed of three PMOS and three NMOS transistors, where the PMOS transistors
• the input signal Al is brought to the PMOS and NMOS transistor GASAD areas, respectively, along a pair of first level stripes 171 and 174; the input signal IN2, along first level stripes 172 and 175, respectively, and the input signal IN3, along first level stripes 173 and 176, respectively, in particular, the first level stripe 171 has a right-hand portion serving as a gate electrode for a PMOS transistor whose source region 141 is connected by a top portion of second level stripe 151 to the VDD power line 110 and whose drain is supplied by diffused p-type impurity region 142 connected at its extreme right-hand portion to a second level stripe 160.
• This impurity region 142 also serves as source region for another PMOS transistor whose drain is supplied by another p-type impurity region 143, which is also connected to the second level stripe 151, and whose gate electrode is supplied by a right-hand portion of the first level stripe 172.
• the impurity region 143 in turn also supplies the source of yet another PMOS transistor whose drain is supplied by yet another p-type impurity region 144 connected at its extreme right-hand portion to the second level stripe 160.
• the three PMOS transistors whose gate electrodes are thus 171, 172, and 173 (by inspection of FIG. 1) thus have their source-drain paths (i.e. , their electrical current paths) all connected in parallel, as is desired in the PMOS portion of a three-input NAND gate. These gate electrodes thus receive as inputs the signals Al, IN2, and IN3, respectively, for these three PMOS transistors.
• the input signal Al on the second level stripe 181 is also delivered to first level stripe 174, where right-hand portion serves as a gate electrode for an NMOS transistor having as its drain an n-type impurity region 145 and having as its source an n-type impurity region 146.
• the region 145 is connected through a second level stripe 153 and thence through a third level stripe 152 to the second level stripe 160.
• the impurity region 146 also serves as drain for another NMOS transistor where gate electrodes are supplied by a right-hand portion of the first level stripe 175, which brings in the input signal IN2, and whose source is supplied by another n-type impurity region 147.
• This n-type region 147 also serves as drain of yet another NMOS transistor whose gate electrode is supplied " by first level stripe 176 which brings in the input signal IN3, and whose source is supplied by yet another n-type impurity region 148.
• This n-type region 148 is connected through a second level stripe 154 to the VSS power line 120.
• the three NMOS transistors whose gate electrodes are 174, 175, and 176 thus have their source-drain paths connected in series between power lines VDD and VSS, as is desired in the NMOS portion of the three-input NAND gate 140, the output of which is supplied through the second level stripe 153 and thence through third level stripe 152 to the second level stripe 160.
• the second level stripe 160 is connected to a pair of third level stripes 161 and 162, located in different routing channels, in order to bring the output of the NAND gate 140 to other cells (not shown) located in the cell rows adjacent to these channels.
• the second level stripe 153 and the third level stripe 152 can both be omitted if the impurity region 145 is extended in the right-hand direction and its right-hand extremity is connected directly to the second level stripe 160.
• the outputs of inverters 125, 130, 60 and 70 are easily accessible by probes connected to third level stripes 122, 132, 63 and 71, respectively.
• the three-input NAND gate 140 (FIG. 1) can be expanded into a five-input NAND gate 300 (FIG. 3) --to accommodate five input signals II, 12, 13, 14, and 15 — by adding two NMOS transistors and two PMOS transistors on the right-hand side as indicated in FIG. 3.
• this expansion from a three- input into a five-input NAND gate does not entail extra space between the VDD and VSS power lines but entails extra space only along the row direction, so that there is no need to increase the distance between the VSS and VDD power lines to accommodate the five- input gate. Such an increase would cause undesirable waste of space elsewhere in the rows.
• the inputs II, 12, 13, 14, and 15 are brought to the five-input NAND gate 300 along second level stripes 301, 302, 303, 304, and 305, respectively.
• the second level stripes 301, 302, and 303 are connected to first level stripes 311, 312, and 313, respectively, in the PMOS area and to first level stripes 321, 322, and 323, respectively, in the NMOS area.
• These first level stripes at their right-hand portions serve as gate electrodes overlying PMOS-GASAD area 310 and NMOS-GASAD area 320, as shown in FIG. 3.
• second level stripes 304 and 305 are connected to first level stripes 334 and 335, respectively, in the PMOS area and to first level stripes 344 and 345, respectively, in the NMOS area.
• These first level stripes serve at their left-hand portions as gate electrodes overlying PMOS-GASAD area 310 and NMOS-GASAD area 340, also as shown in
• the third level power line VDD is connected to the PMOS-GASAD area 310 through second level stripes 315 and 336 through four windows: a window located between first level stripes 312 and 313, a window located at the left-hand top extremity of the PMOS-GASAD area 310 (just above first level stripe 311), a window located at the right-hand top extremity of this PMOS area 310 (just above first level stripe 335), and a window located at the bottom right-hand extremity of this area 310 (just below first level stripe 334) .
• the third level power line VSS is connected to NMOS-GASAD area 320 through second level stripes 325 as shown in FIG. 3.
• the NMOS-GASAD areas 320 and 340 are respectively interconnected at their top extremities by second level stripes 326 and 342, through a third level stripe 341.
• the output Z of the five-input NAND gate 300 is delivered along second level stripe 350 by virtue of its connection through third level stripe 346 and second level stripe 343 to the bottom extremity of the NMOS-GASAD area 340 and its direct contacts to an elongated portion of the bottom of the left-hand portion of PMOS-GASAD area 310 and to an interconnecting portion (between imaginary extensions toward the right of first level stripes 311 and 312, and to the left of first level stripes 334 and 335) of this PMOS-GASAD area 310.
• a six-input NAND gate can be laid out similarly as the above-described five-input NAND gate 300, likewise without increasing the distance between power lines VDD and VSS, by adding one more first level stripe to the right-hand side of PMOS-GASAD area 310 between first level stripes 334 and 335, and adding one more first level stripe to the NMOS-GASAD area 340 between first level stripes 344 and 345, both such added first level stripes being contacted by a second level input stripe for bringing in the sixth input signal.
• ⁇ kx. layer 503 (gate oxide) extending over a transistor channel region located at the top surface of the body 500 between the n-type source region 119 and the n-type drain region 118, as known in the art of CMOS transistors.
• first level stripe 117 serving there as the gate electrode.
• the drain and source regions 118 and 119 are contacted by second level stripes 116 and 121, respectively.
• the stripes 116 and 121 are both separated and insulated from the body and from the first level stripe 117 by a second insulating layer 505 located on the first insulating layer.
• the third level stripes 120 and 122 are separated and insulated from the second level stripes 121 and 116 respectively, by a third insulating layer 507, except that the third level stripes 120 and 122 contact the second level stripes 121 and 116, respectively, through windows 410 and 412 in this third insulating layer 507.
• a protective insulating cap layer 509 is located on the third insulating layer 507 and on the third level stripes 120 and 122.
• the insulating layers are made of known material (s) , or of other materials as they become available in the CMOS art.
• the first level stripe 117 is essentially doped or undoped polysilicon, and may be overlaid with metal suicide for greater conductivity if needed. It is also feasible to dope the polysilicon stripes 117 serving as gate electrodes for the PMOS transistors differently from the stripes serving as gate electrodes for the NMOS transistors.
• the second and third level stripes 120, 122, 121, and 116 are all essentially aluminum or other metal(s) or combination(s) thereof. It should be understood that at areas of the circuit region 5 (FIG.
• the first insulating layer is made thicker than at (gate) areas overlying transistor channel regions located between sources and drains; and the second insulating layer may also be made correspondingly thicker at areas removed from the GASAD areas.
• the first, second, and third levels of interconnections are planar except for transition areas overlying the boundaries of GASAD areas (and perhaps also overlying the edges of first and second level stripes) .
• programmed logic arrays and/or memories can be fabricated in other regions of the circuit using the above-described three levels of interconnection without using the cell row arrangement of the kind described above--i.e., without having elongated rows dedicated to transistors plus some interconnections but while still using three levels of interconnections, for example, one polysilicon and two aluminum levels.
• routing insofar as routing (layout) of interconnection from one cell to another whether located in the same row or in different rows
• the routing of interconnections in the channel can be the same as in the case of the two level scheme of prior art simply by considering the first prior art level (of polysilicon) as the new second level (of metal), and the second prior art level (of metal) as the new third level (also of metal). Accordingly, the same computer-aided routing tools can be used for layout of routing when implementing interconnections in accordance with this invention as were used in the prior art.
• the gate electrode of an NMOS transistor in a given cell can be directly (i.e. , without running into the channel) interconnected to the gate electrode of a PMOS transistor within the same cell via a second level (metal) stripe located within the 5 polycell instead of via solely first level (polysilicon) stripes—an advantage of special importance in the case of submicron transistor feature sizes where the close proximity of the PMOS to the NMOS gates runs the risk of undesirable diffusion of the significant impurities in
• first level metal silicide overlay as in prior art is correspondingly relaxed, and hence the first level stripes can be polysilicon doped with impurities but not containing any metal silicide.

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• 1986
  • 1986-07-14 EP EP86904665A patent/EP0231271A1/de not_active Withdrawn
  • 1986-07-14 KR KR870700270A patent/KR880700464A/ko not_active Application Discontinuation
  • 1986-07-14 JP JP61503846A patent/JPS63500555A/ja active Pending
  • 1986-07-14 WO PCT/US1986/001462 patent/WO1987000969A1/en not_active Application Discontinuation

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