INTEGRATED CIRCUIT SEMICONDUCTOR DEVICE HAVING IMPROVED WIRING STRUCTURE

Abstract: An integrated circuit semiconductor device having an im­ proved power supply wiring structure is disclosed. The wiring includes a wide conductive layer and a plurality of stripe type narrow conductive layers formed on the wide conductive layer via an insulating film. Each of stripe type conductive layers is connected to the wide conductive layer through a plurality of contact holes provided in the insulating film.

Description: Background of the Invention: The present invention relates to an integrated circuit semiconductor device having an improved wiring structure and more particularly, to a power supply wiring for a gate array type integrated circuit device. In the gate array technique, various basic circuits such as TTL output buffer circuits and ECL output buffer circuits are fabricated in advance on a master substrate and "personalisation wirings" or "application specific wirings" are made by interconnecting selected basic circuits and connecting power supply lines to selected basic circuits to obtain a desired function for a specific application. The power supply lines are generally made of a wiring layer which should have a thickness as large as possible in order to reduce a resistivity thereof and decrease an unfavorable level shift in the wiring layer. However, the thickness of a single conductive layer such as aluminum layer has a limit, for example, of 2 µm or less because of fine patterning, uniformity of the thickness and reliable maintenance of manufacturing apparatus such as vacuum evaporation apparatus by which the layer is formed. It has been accordingly practised to form the power supply line or a signal line of a low resistivity with double conductive layers, a lower layer and an upper layer superposed thereon via insulating film and electrically connected to the lower layer through a plurality of contact holes formed in the insulating film. The two layers have the same pattern or shape in a plane view. The double-layer low-resistivity power supply or signal line requires at least three masks for formation thereof on the integrated circuit substrate, a first mask for the lower-level layer, a second mask for the contact holes and a third mask for the upper-level layer. A different double-layer line requires different three masks. In other words, three masks must be newly designed and produced when a pattern of the double-layer line is changed. This is disadvantageous, particularly in the gate array device in which a large number of masks are fixed and only such masks are changed in accordance with a function required for the specific application that are necessary to form the personalization wirings. In European Patent Application No. 103362 published on March 21, 1984, there is described an integrated circuit semiconductor device of a gate array type having TTL input/output buffer circuits, which device comprises power supply lines for supplying a first and a second voltage, the power supply lines being formed at a first level and extending in one direction, one of them being overlapped by a stripe type conductive layer at a second level separated from the first level by an insulating film, which layer extends in the same direction and is electrically connected to said one power supply line through a plurality of contact holes formed in the insulating film, thus forming a double-layer low resistivity power supply line. In European Patent Application No. 154998 published on September 18, 1985, there is described an integrated circuit semiconductor device having a lower conductive layer for supplying a first voltage covered by an insulating film and first and second upper conductive layers extending parallel to each other and overlapping the lower conductive layer to which they are connected through a plurality of contact holes. It is an object of the present invention to provide an integrated circuit semiconductor device having a double-layer low resistivity line in which a change in pattern of the double-layer low-resistivity line does not bring about a complete change in a plurality of masks. An integrated circuit semiconductor device in accordance with the invention is defined in claim 1. In an embodiment to be described either the upper-level layer or the lower-level layer is comprised of a plurality of parallel-arrayed unit stripes of the conductive material which have the same length and the same width. The length may be different in a different group of the unit stripes. The width is made small, not more than a possible narrowest width of the line. A pattern of the contact holes is fixedly determined in accordance with the pattern of the unit stripes of the upper-level (or lower-level) layer. A pattern of the lower-level (or upper-level) layer is determined in accordance with the layout of the double-layer line such that it is overlapped by (or overlaps) one or a plurality of the unit stripes of the upper-level (or lower-level) layer. The semiconductor integrated circuit to be described comprises a semiconductor substrate, first and second conductive layers of one level formed on the substrate via an insulating layer and extending in one direction, and at least three stripe type conductive layers of another level formed on the substrate via an insulating film and arrayed in parallel with each other with a constant interval, each extending in the one direction. Each of the stripe type conductive layers has the width equal to or narrower than the widths of the first and second conductive layers and is positioned above or below either the first or the second conductive layer so as to overlap it or to be overlapped thereby and connected to the overlapped first or second conductive layer via a plurality of contact holes arrayed in the one direction and formed in the insulating film between the stripe type conductive layer and the overlapped first or second conductive layer. The number of the stripe type conductive layers may be four or more. The double-layer wiring structure of the present invention may be employed in a gate array type integrated circuit semiconductor device. Brief Description of the Drawings: Fig. 1A, Fig. 2A and Fig. 3 are plan views showing embodiments of the present invention; Fig. 1B and Fig. 2B are cross-sectional views taken along lines B-B' in Fig. 1A and Fig. 2A as viewed in the direction of arrows, respectively, and Fig. 1C and Fig. 2C are cross-sectional views taken along lines C-C' in Fig. 1A and Fig. 2A as viewed in the direction of arrows, respectively. Description of the Embodiments: Referring to Figs. 1A to 1C which show power supply wiring lines on one peripheral portion of a TTL and ECL input/output mixed type gate array integrated circuit chip, the power supply wiring lines comprise a highest-potential power supply voltage (Vcc) line 900 and 400, intermediate-potential power supply voltage (ground) lines 300 and a lowest-potential power supply voltage (V EE ) line 500, 700 and 800. These three kinds of lines are made of aluminum layer. The aluminum layers for signal lines and the power supply lines are formed at first, second and third levels on the field silicon oxide film 51 provided on the major surface of the silicon substrate 50 with intermediate insulating films 52 and 53 interposed therebetween. The V EE line 500 is electrically connected to the bonding pad 31 of the third level aluminum layer and includes the lower aluminum layer 33 of the second level and the upper aluminum layer 32 of the third level which is continuously extended from the bonding pad 31 and electrically connected to the lower aluminum layer 33 through a plurality of contact holes (not shown in Fig. 1A but similar to contact holes 54 in Figs. 1B and 1C). The V EE line 700 includes the lower aluminum layer 19 of the second level electrically connected to the lower aluminum layer 33 of the line 500 via the aluminum layer 16 of the first level to which the layers 33 and 19 are connected through the contact holes 17 provided in the intermediate film 52. The V EE line 700 further includes the upper aluminum layer 18 of the third level connected to the lower aluminum layer 19 through a plurality of contact holes (not shown but similar to the contact holes 54 in Figs. 1B and 1C). The V EE line 800 is comprised of the lower aluminum layer 35 of the second level connected to the lower aluminum layer 33 of the line 500 via the aluminum layer 36 of the first level which is connected to the layers 33 and 35 through contact holes 37 provided in the intermediate insulating film 52 and, two stripe type upper aluminum layers 62 of the third level. Each of the upper layers 62 is connected to the lower aluminum layer 35 through a plurality of contact holes 54 (Fig. 1B and Fig. 1C) provided in the intermediate insulating film 53. The V EE line 800 is connected to ECL output buffer circuits (not shown) via the aluminum layer 38 of the first level which is connected to the lower layer 35 of the line 800 through the contact hole 39. The V GND line 300 includes a plurality of stem lines (shown in Fig. 1A are three) connected to a plurality of aluminum bonding pads 11 of the third level (shown are four) and a plurality of branch lines (shown are two) extended from the stem line. Each of the stem and branch lines has the lower aluminum layer 13 of the second level and the upper aluminum layer 12 of the third level which is connected to the lower aluminum layer 13 through a plurality of contact holes (not shown). The bonding pads 11 are connected to the upper aluminum layers 12. The Vcc line 900 includes the lower aluminum layer 23 of the second level which is connected to TTL output buffer circuits (not shown) via the aluminum layer 28 of the first level which is in turn connected to the layer 23 through the contact hole 29. The Vcc line 900 further includes two stripe type upper aluminum layers 62 of the third level and a short wiring 22 of the upper aluminum layer of the third level connected to the bonding pad 21. Each of stripe type upper aluminum layers 62 is connected to the lower aluminum layer 23 through contact holes 54 shown in Fig. 1C. The short wiring 22 of the third level is continuously extended from the bonding pad 21 and connected to the lower aluminum layer 23 through a plurality of contact holes (not shown). Other Vcc lines 400 have the lower aluminum layers 25 of the second level electrically connected to the lower aluminum layer 23 of the Vcc line 900 via the aluminum layer 26 of the first level which is connected to the layers 25 and 23 through contact holes 27 and the upper aluminum layers 24 of the third level connected to the respective lower aluminum layers 25 through a plurality of contact holes (not shown). Besides the above-mentioned voltage supply lines 300, 400, 500, 700, 800 and 900, other voltage supply lines 60 are provided which include parallel-arranged stripe type aluminum layers of the third level. The aluminum layers 16, 36, 26, 28 and 38 of first level are formed on the field silicon oxide film 51 provide on the major surface of the P-type silicon substrate 50 and have 1.0 µm thickness. The aluminum wiring layers 33, 19, 23, 13, 35 and 25 of the second level having 1.2 µm thickness are formed on the first intermediate insulating film 52 made of silicon oxide or silicon nitride and having 0.5 µm thickness which covers the first level aluminum layers and the field insulator film 51. The layer 35 has 116 µm width and the layer 23 also has the width of 116 µm. The aluminum layers 32, 18, 62, 12, 22 and 24 of the third level of 1.6µm thickness are provided on the second intermediate insulating film 53 made of silicon oxide or silicon nitride and having 0.5 µm thickness which covers the second-level aluminum layers and the first intermediate insulating film 52. The third-level aluminum layers are connected to the respective second-level layers through a plurality of contact holes provided in the second intermediate insulating film 53 as mentioned above. The stripe type aluminum layers 62 of the present invention have the width (W) of 46 µm and are arranged in parallel with each other with the constant pitch (P shown in Fig. 1C) of 66 µm. Therefore an interval between the adjacent layers 62 is 20 µm. Referring to Figs. 2A to 2C showing a second embodiment in which the gate array device includes a larger number of TTL output buffer circuits (not shown) and a smaller number of ECL output buffer circuits (not shown) than in the first embodiment, the pattern of the third-level aluminum layers including the stripe type aluminum layers 62 is not changed from that of the first embodiment shown in Fig. 1A. Nevertheless, the V EE line 810 to the ECL output buffer circuits has a smaller width and the Vcc line 910 to the TTL output buffer circuits is wider. The pattern of the second-level aluminum layer 135 of the V EE line 810 is changed to have a 50 µm width and only one of the stripe type aluminum layers 62 of third level (46 µm in width) is thereby connected to the lower layer 135 through a plurality of contact holes 54 arranged in the lengthwise direction. The pattern of the second-level aluminum layer 123 of the Vcc line 910 is changed to have a 182 µm width and three of the stripe-type aluminum layers 62 of third level are thereby connected to the lower layer 123 through a plurality of contact holes 54 arranged in each lengthwise direction. The width (W) and the pitch (P) of the stripe-type layers 62 shown in Figs. 2C are the same in Fig. 1C. In Figs. 2A to 2C, the same components as those in Figs. 1A to 1C are indicated by the same reference numerals. Referring to Fig. 3 showing a third embodiment in which the gate array device uses only ECL buffer circuits and no TTL buffer circuit is used, no Vcc line is provided and only V GND lines and V EE line are used. Nevertheless again, there is no change in Fig. 3 in pattern of the third-level aluminum layers including the stripe type layers 62 from that of Fig. 1A. No change in mask is therefore required. Only the pattern of the second-level aluminum layers is changed such that the lower layer 23 (in Fig. 1A) is separated from the portion under the upper layer 22 and extended towards the lower layer 13 of the central V GND line 300 to be connected thereto, thus becoming a lower layer 223 of another branch 300' of the V GND line. The layer 28 connected to this V GND branch line 300' is extended to ECL buffer circuits rather than TTL buffer circuits. The portion of the lower layer under the upper layer 22 is connected to the lower layer 133 of another V GND line. The ground potential V GND is applied to the bonding pad 21 connected to the short wiring 22, instead of the Vcc potential. In Fig. 3, the same components as those in Fig. 1A are indicated by the same reference numerals.

Claims: An integrated circuit semiconductor device including a semiconductor substrate (50); an insulating layer (51) formed on a major surface of the substrate (50); and layers of metallization of various levels for signal and power supply lines with intermediate insulating films (52,53) interposed between them; the layers of metallization including a first conductive layer (23, 123, 223) of one level belonging to a first power supply line for supplying a first voltage, the first conductive layer (23, 123, 223) being formed on one of the insulating films (52) and extending in one given direction, a second conductive layer (35, 135) of the one level belonging to a second power supply line for supplying a second voltage different from the first voltage, the second conductive layer (35, 135) also being formed on said one of the insulating films (52) and extending in the one direction in parallel with the first conductive layer (23, 123, 223), and at least three stripe type conductive layers (62) of another level different from said one level being separated from said first and second conductive layers by the second insulating film (53) and extending in the one direction parallel to each other with constant intervals; at least one of the stripe type conductive layers (62) overlapping one of the first and second conductive layers (23, 123, 223) (35, 135) via the second insulating film (53) and all of the remaining stripe type conductive layers (62) overlapping the other of the first and second conductive layers (23, 123, 223) (35, 135) via the second insulating film (53); and each of the stripe type conductive layers (62) being electrically connected to the respective overlapped one of the first and second conductive layers (23, 123, 223) (35, 135) through a plurality of contact holes (54) formed in the second insulating film (53) and arranged in the one direction, thus forming double-layer low resistivity power supply lines (900, 800, 910, 810, 300). An integrated semiconductor device of claim 1, in which the number of said stripe type conductive layers (62) is four or more. An integrated semiconductor device of claim 1, in which said stripe type conductive layer (62) have substantially the same width (W). An integrated semiconductor device of claim 1, in which said device is of a gate array type having TTL input/output buffer circuits and ECL input/output buffer circuits.

Inventors: KOBAYASHI, MASAHARU
Applicants: NEC CORPORATION
Application year: 1987
Main classification: H01L23
IPC codes: H01L23, H01L27, H01L21