EP0403571A4 - Gate array structure and process to allow optioning at second metal mask only - Google Patents
Gate array structure and process to allow optioning at second metal mask onlyInfo
- Publication number
- EP0403571A4 EP0403571A4 EP19890904937 EP89904937A EP0403571A4 EP 0403571 A4 EP0403571 A4 EP 0403571A4 EP 19890904937 EP19890904937 EP 19890904937 EP 89904937 A EP89904937 A EP 89904937A EP 0403571 A4 EP0403571 A4 EP 0403571A4
- Authority
- EP
- European Patent Office
- Prior art keywords
- metal
- layer
- conductive
- vias
- portions
- Prior art date
- 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.)
- Withdrawn
Links
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
- 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
- H01L23/525—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 with adaptable interconnections
- H01L23/5256—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 with adaptable interconnections comprising fuses, i.e. connections having their state changed from conductive to non-conductive
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76838—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the conductors
- H01L21/76886—Modifying permanently or temporarily the pattern or the conductivity of conductive members, e.g. formation of alloys, reduction of contact resistances
- H01L21/76892—Modifying permanently or temporarily the pattern or the conductivity of conductive members, e.g. formation of alloys, reduction of contact resistances modifying the pattern
-
- 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 at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier
- H01L27/04—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 at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body
- H01L27/10—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 at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration
- H01L27/118—Masterslice integrated circuits
-
- 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 a process and structure for
- Gate arrays are arrays of semiconductor circuit elements
- interconnects are applied according to a custom pattern to
- the electrical interconnects usually
- a final passivation layer is usually applied and 6 patterned for protection from the elements.
- a final passivation layer is usually applied and 6 patterned for protection from the elements.
- 7 8 SUMMARY The structure and process of this invention allow for applying the first layer of metal, and patterning it with a universal (usable for many custom circuits) first layer mask, depositing the dielectric and patterning this with a universal via mask, and depositing the second layer of metal, all as part of the standard portion of producing a gate array integrated circuit. Custom masking steps to complete a circuit are then required only for patterning the second layer of metal. As a novel feature of this invention, the step of patterning the second layer of metal also selectively opens connections in the first layer of metal, thus producing the intended circuit function.
- the structure and method of this invention decrease the time and number of custom steps remaining to complete the integrated circuit after it is ordered in comparison to a standard gate array metallization process.
- the cost of manufacture is also significantly reduced because only one custom mask is required.
- the structure and process of this invention also have a larger tolerance for alignment error in the relative locations of the first metal layer lines, the vias and the second metal layer lines. in contrast to the prior art, by making vias wider than the lines which they will connect, and by planarizing the insulation layer deposited on the first metal before forming the vias, the step of etching after patterning and depositing second metal removes not only the second metal from unwanted areas but also removes second metal extending into vias located beneath exposed second metal and further removes the first metal located beneath these exposed vias.
- a standard -> first metal pattern having excess interconnections can be * ⁇ " * manufactured, and unnecessary first metal interconnections cut during the second metal patterning step to form a
- a preferred standard layout provides first layer metal 1* - ) everywhere it is likely to be needed in any of many possible H circuit designs.
- a preferred standard layout also provides • - • 2 oversized vias above first layer metal everywhere it is
- a layer of a 28 barrier metal which responds differently to the etchant used 29 for etching first layer metal can be placed over these 30 portions of first layer metal so that etching the second
- barrier metal Providing this barrier metal allows oversized vias.
- Second metal can likewise be made smaller. This means that
- Figs, la and lb show in plan and side views a first
- FIG. 2 shows the structure of Fig. lb with the addition
- FIG. 3 shows the structure of Fig. 2 with the addition
- Fig. 4a shows the structure of Fig. 3 planarized to the
- Fig. 4b shows the structure of Fig. 4a with a dielectric
- Figs. 5a and 5b show plan and cross-sectional views of
- Fig. 6 shows the structure of Fig. 5b with the addition
- Fig. 7 shows the structure of Fig. 6 to which a custom
- FIGs. 8a and 8b show the structure of Fig. 7 in which
- FIG. 9 shows the structure of Fig. 8b to which a final
- Fig. 10 shows the side view of a structure similar to
- Figs, lla-lle show plan view layouts of vias
- Figs, la and lb show respectively a top view and a cross sectional view, the cross section of Fig. lb taken along line A-A of Fig. la, which shows a first metallization layer deposited on a gate array substrate.
- the same numerical designations represent the same elements throughout the description and figures.
- the layout shown in Fig. la is commonly used for forming CMOS structures having groups of four transistors useful for implementing AND, OR, NAND, NOR and other logic functions.
- Fig. lb shows P-type substrate 51, which has formed therein N-type well 51a. Before formation of metallization layer 53, an oxide insulation layer 52 will have been formed on the surface of the substrate, and gates such as gate 24 (Fig.
- metallization layer 53 first metal
- Source and drain region contacts at locations such as 53a, 53b, 53c, and 53d, and has been patterned to produce metal interconnects. Oxide regions 52a and 52c are thus exposed.
- a single gate, such as gate 24 shown in Fig. la controls adjacent N-channel and P-channel transistors.
- the N-channel transistor has drain contacts 53c, 53d.
- the P-channel transistor has drain contacts 53a, 53b.
- polycrystalline silicon gate 24 controls electron flow through two substrate channels, for example between the source region located beneath contact 53e and the drain region located beneath contact 53d.
- Each source, drain, channel and gate comprise one MOS transistor.
- the particular logic function depends upon the patterning of first and second metal connections. According to the present invention, custom patterning of both first and second metal to achieve a wide variety of logic functions can be performed in a single step, as will be described. 1 Next, ' in order to planarize metallization layer 53, a
- photoresist layer 55 and insulation layer 54 are etched by a process which removes photoresist 55
- Etching is continued until upper portion 54a of 0 insulation layer 54 is removed and first metallization layer 1 53 is exposed. The etch may be ended at an earlier point
- polyimide will absorb moisture if left
- insulation layer 54 can produce leveling.
- spin-on glass allows insulation layer 54 to be planarized directly.
- Fig. 5a shows a plan view and Fig. 5b shows a cross- sectional view in which insulation layer 56 has been deposited and vias 56a, 56b, 56c, 56d and 56e have been formed at all locations where it may later be desirable to connect second metal to first metal or to break contact in the earlier formed first metal.
- Fig. 5b is a cross-sectional view of Fig. 5a taken along the line A-A. As shown in Fig.
- insulation layer 56 is deposited onto the top of the planarized layer comprising metallization layer 53 and insulation layer 54. Passivation layer 56 is then patterned to form vias such as 56a, 56b, 56c, 56d and 56e.
- second metallization layer 57 is deposited onto the top surface of the semiconductor wafer forming contact regions 57a, 57b, 57c, 57d and 57e in the vias which were formed in insulation layer 56. All these steps are part of forming a universal semi- conductor structure which can be used for multiple custom circuits, depending upon the mask used for patterning of second metal layer 57. Figs.
- photoresist layer 58 is deposited onto second metal layer 57 and patterned into regions 58a, 58b, 58c, and 58d using the single custom mask which can be used with this invention. This patterning exposes locations at which second and also some first metal are to be removed. As shown in Fig. 8b, these exposed portions are removed. The remaining photoresist is also removed. A plasma or reactive ion etching process can be selected to avoid undercutting of first and second metal. n Fig. 8b, portions of second metal 57, some of the second metal contacts, and portions of the first metal have been removed.
- the resulting circuit is shown in plan view in Fig. 8a. " As shown in Fig. 9, after removal of unwanted portions of first and second metal, a final passivation layer 59 is formed. As shown in Fig. 8b, the patterning step has resulted in the removal of second metal region 57g (shown in Fig. 7), thereby severing the connection between second metal regions 57f and 57e. The patterning has also resulted in removal of second metal contact regions 57c part of second metal contact regions 57b and 57d, plus the further removal of first metal regions 53h, 53 , and 53 ⁇ (see Fig. 8b). Therefore connections have been severed between second metal region 57a and first metal region 53i.
- first metal lines can be made narrower than under prior art design rules while maintaining sufficient alignment error tolerance for vias.
- a prior art device which does not planarize the insulation layer above first metal must keep the vias from overlapping first metal because without planarizing an etch step would etch or at least expose the silicon substrate.
- Design rules may require above the first metal lines a 1-micron space on each side of a via to allow for alignment error and avoid having the vias overhang the first-metal line.
- the prior art line width must be 5 microns. Eliminating the prior art requirement that vias not overhang first metal allows the first metal to be at least 2 microns smaller, and if vias are permitted (or desired) to overhang first metal, the first metal lines can be shrunk, in our example, from a 5-micron width to a one- or two-micron width.
- the design rules can be remarkably shrunk and the overall device made remarkably smaller. This same principle will apply if in the future tolerances become tighter and line widths can e further reduced. i some cases it may be desirable to provide contact between first and second metals through a via, but to allow the contact between first and second metal to be broken without allowing the first metal line to be broken. in this case, after forming and patterning the first metal layer, and forming and patterning the insulation layer above it, a thin layer of a barrier metal is deposited and patterned before the second metal layer is deposited. The barrier metal formation increases the number of steps needed to form the structure, however these extra steps occur during formation of the universal structure and do not lengthen the customization process. The number of custom masks needed remains one.
- the barrier metal is selected to be resistant to an etchant used to etch the first and second metal lines.
- the barrier metal is patterned to be located above vias in the insulation layer where it is desirable not to break, the first metal layer beneath the vias.
- Fig. 10 shows a side view of a structure in which a barrier metal has been used. As shown in Fig. 10, two regions 61 and 62 of first metal have been formed. Planarization oxide layer 63 has been followed by the formation and patterning of oxide layer 64. After formation of these oxide layers, a layer 65 of barrier metal was formed and patterned. As shown in Fig. 10, barrier metal region 65 is larger than the first metal regions 61a and 61b it must protect. Thus, alignment is not critical. In customizing the structure of Fig.
- the goal is to leave region 66b of second metal connecting first metal region 61a to first metal region 62a, also to sever the connection from second metal region 66a to first metal regions 61a or 61b and to sever the connection between first metal regions 62a and 62b but "not to sever the connection between regions 61a and 61b.
- barrier metal 65 has been patterned to cover first metal regions 61a and 61b but not to cover first metal regions 62a and 62b.
- the second metal layer contacts first metal regions 61a and 61b through barrier metal 65 and via 68a.
- the second metal layer contacts regions 62a and 62b through via 68b.
- the single custom mask patterns the photoresist to cause openings to be etched in second metal at regions 69a and 69b» Etching of opening 69a is stopped by barrier metal 65 while etching of opening 69b proceeds in region 69c until regions 62a and 62b are separated. At this point in the process, barrier metal layer 65 connects second metal region 66a to first metal regions 61a and 61b. A subsequent etch of this barrier metal (not requiring further masking and patterning) removes the exposed portions of barrier metal 65, thus severing connection from second metal region 66a to first metal regions 61a and 61b. Tolerance in alignment of the barrier metal is not critical because the barrier metal region may be made sufficiently larger than the via it is to cover.
- barrier metal does not further restrict alignment tolerances for the custom mask. Opening 69a between second metal regions 66a and 66b need be only wide enough to assure separation between these adjacent second metal regions. Alignment between the custom mask and the cell to be customized must only be sufficient that region 66b contacts region 61a and 62a, that the first metal gap between regions 62a and 62b is sufficient for reliable separation, and that region 66a is separated from region 61b.
- a barrier metal which has been successfully used with a silicon substrate, silicon oxide insulation, and aluminum first and second metal is titanium-tungsten.
- first metal layer 11 was patterned after deposition to leave a cross-shaped pattern as indicated by outline 11-3. After forming an insulation layer above the patterned first metal cross-shaped pattern, via 12 is patterned into the insulation layer, thus exposing the center of first metal cross 11-3.
- Fig. lib shows the remaining structure after patterning of second metal 13, in which only an L-shaped portion of second metal 13 remains.
- region 12-1 the removal of second metal 13 where via 12 is located has resulted in removal of first metal 11 from the original cross-shaped first metal pattern 11-3, thus severing electrical connection between first metal region 11-1 and first metal regions 11-2 and 11-4.
- the presence of the insulation layer above first metal regions 11-1 and 11-2 prevents the subsequent removal of second metal 13 from also removing first metal regions 11-1 and 11-2.
- second metal remains above but separated by insulation layer 12 from first metal.
- second metal 13 is in contact with first metal 11.
- the second metal pattern selected in Fig. lib has resulted in retaining the electrical connection between first metal regions 11-4 and 11-5 while severing connections to first metal regions 11-1 and 11-2.
- Other patterns are shown in Figs. 11a, lie, lid, and lie.
- Fig. lid a first metal line over which a via is located has been severed during second metal patterning.
- Fig. lie first metal region 15-2 has been severed from first metal region 15-3 while remaining connected to second metal region 15-1.
- second metal region 17-1 connects regions 16-1 and 16-3 to each other but leaves region 16-2 disconnected.
- Second metal can also pass above first metal regions covered by an insulation layer and provide a jumper between remote portions of first metal or remote portions of the semiconductor substrate.
- Second metal can also pass above first metal regions covered by an insulation layer and provide a jumper between remote portions of first metal or remote portions of the semiconductor substrate.
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US17583488A | 1988-03-31 | 1988-03-31 | |
US175834 | 1988-03-31 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0403571A1 EP0403571A1 (en) | 1990-12-27 |
EP0403571A4 true EP0403571A4 (en) | 1991-01-30 |
Family
ID=22641830
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890904937 Withdrawn EP0403571A4 (en) | 1988-03-31 | 1989-03-29 | Gate array structure and process to allow optioning at second metal mask only |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0403571A4 (en) |
JP (1) | JP3104232B2 (en) |
WO (1) | WO1989009492A1 (en) |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3877051A (en) * | 1972-10-18 | 1975-04-08 | Ibm | Multilayer insulation integrated circuit structure |
JPS6018143B2 (en) * | 1976-12-23 | 1985-05-09 | 富士通株式会社 | Manufacturing method of semiconductor integrated circuit |
US4172004A (en) * | 1977-10-20 | 1979-10-23 | International Business Machines Corporation | Method for forming dense dry etched multi-level metallurgy with non-overlapped vias |
DE3066941D1 (en) * | 1979-05-24 | 1984-04-19 | Fujitsu Ltd | Masterslice semiconductor device and method of producing it |
JPS57177553A (en) * | 1981-04-24 | 1982-11-01 | Toshiba Corp | Semiconductor |
JPS5837933A (en) * | 1981-08-31 | 1983-03-05 | Hitachi Ltd | Semiconductor integrated circuit device |
IL82113A (en) * | 1987-04-05 | 1992-08-18 | Zvi Orbach | Fabrication of customized integrated circuits |
-
1989
- 1989-03-29 EP EP19890904937 patent/EP0403571A4/en not_active Withdrawn
- 1989-03-29 WO PCT/US1989/001307 patent/WO1989009492A1/en not_active Application Discontinuation
- 1989-03-29 JP JP50473189A patent/JP3104232B2/en not_active Expired - Fee Related
Non-Patent Citations (2)
Title |
---|
No further relevant documents have been disclosed. * |
See also references of WO8909492A1 * |
Also Published As
Publication number | Publication date |
---|---|
EP0403571A1 (en) | 1990-12-27 |
JPH02503972A (en) | 1990-11-15 |
WO1989009492A1 (en) | 1989-10-05 |
JP3104232B2 (en) | 2000-10-30 |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
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