Method of forming semiconductor integrated circuit using master slice approach

Abstract: A method of forming a semiconductor integrated circuit using a master slice approach includes the steps of: forming a plurality of transistor regions (TR) with units of a predetermined number in array on a semiconductor chip; forming a plurality of first wirings (LA) extending in parallel at a space therebetween with units of a predetermined length in a discontinuous form so that the first wirings pass through regions corresponding to the transistor regions; forming first contact holes (NA) at predetermined positions so that gate regions (G) and source/drain regions (S/D) of the transistor regions are connected to the first wirings; forming a plurality of second wirings (LB) having same forms as the plurality of first wirings so that the second wirings constitute a mesh-like arrangement in combination with the first wirings; and forming second contact holes (NB) using a pattern mask programmable in accordance with demanded conditions of a given circuit so that the second contact holes connect the second wirings to the first wirings. By changing only the form of the disposition of the second contact holes, it is possible to simplify an entire process to greatly reduce a turnaround time and make an improvement in yield.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique of utilizing a master slice approach and, more particularly, to a method of forming a semiconductor integrated circuit or large scale integration (LSI) circuit by forming each circuit pattern by units of a functional block on a semiconductor chip, using the master slice approach. 2. Description of the Related Art The master slice approach is one of the fixed wiring approaches based on "LSI on slice" approach. In the master slice approach, a common pattern formed by means of a diffusion process (a transistor pattern called a basic cell in the form of a constant arrangement) is prepared, and then, a wiring pattern is applied to the common pattern the wiring pattern being changed in accordance with the forms of the LSI or the specification or conditions demanded by a user. Therefore, a desired LSI can be constituted by designing and forming the wiring pattern in various ways. In constituting the desired LSI, two kinds of aluminium (Al) wiring pattern masks and two kinds of contact hole pattern masks are generally employed. Note, a first contact hole (hereinafter indicated by reference NA) effects a connection between a conduction region of a functional element such as a transistor formed on the substrate and a first Al wiring (hereinafter indicated by reference LA), and a second contact hole (hereinafter indicated by reference NB) effects a connection between the first Al wiring LA and a second Al wiring (hereinafter indicated by reference LB). Namely, a known typical master slice approach comprises the steps of forming fixed transistor patterns and forming a programmable wiring pattern. The latter step requires four processes of forming first contact holes NA in a first insulation layer formed on the substrate, forming thereon first wirings LA, forming second contact holes NB in a second insulation layer formed thereon, and forming thereon second wirings LB. In this case, each pattern employed in each of the four processes must be changed in accordance with user's demands or the forms of the LSI. This leads to a complication of the process and a prolongation of the designing period, and thus is not preferable. Accordingly, it would be preferable to decrease the number of the processes requiring a change or programming based on the user's demands, from a viewpoint of the reduction of a turnaround time and the simplification of the entire process. Patent Abstracts of Japan volume 9, No 310 (E-364), December 1985, discloses a two layer wiring pattern, which provides a mesh-like structure. This enables different circuit arrangements to be achieved by varying through-hole positions. EP-A-0 133 958 discloses a method of forming a semiconductor integrated circuit using a master slice approach comprising the steps of : forming a plurality of transistor regions in an array on a semiconductor chip and then forming a first insulation layer over all said transistor regions; forming a plurality of first wiring sections, each first wiring section comprising a plurality of first wiring elements which are parallel to and spaced apart from each other, each first wiring element comprising discontinuous portions of a predetermined length so that said first wiring sections pass through regions corresponding to said transistor regions; forming first contact holes at predetermined positions in said first insulation layer so that gate regions and source/drain regions of said transistor regions are connected to said first wiring elements and then forming a second insulation layer over all said first wiring sections and said first contact holes; and forming a plurality of second wiring sections. SUMMARY OF THE INVENTION An object of the present invention is to provide a method of forming a semiconductor integrated circuit which can simplify an entire process and greatly reduce a turnaround time, while making an improvement in yield. A method according to the present invention is defined in claim 1. BRIEF DESCRIPTION OF THE DRAWINGS Other objects and features of the present invention will be described hereinafter in detail by way of preferred embodiments with reference to the accompanying drawings,in which: Fig. 1 is a pattern diagram illustrating a typical example of a transistor pattern; Figs. 2A to 2D are diagrams for explaining the process according to one embodiment of the present invention; Fig. 3 is an equivalent circuit diagram of the pattern shown in Fig. 2C; Figs. 4A to 4C are diagrams illustrating a first example of the pattern by units of a functional block produced using the pattern shown in Fig. 2D; Figs. 5A to 5C are diagrams illustrating a second example of the pattern by units of a functional block produced using the pattern shown in Fig. 2D; Figs. 6A to 6C are diagrams illustrating a third example of the pattern by units of a functional block produced using the pattern shown in Fig. 2D; Figs. 7A to 7C are diagrams illustrating a fourth example of the pattern by units of a functional block produced using the pattern shown in Fig. 2D; Figs. 8A to 8C are diagrams illustrating a fifth example of the pattern by units of a functional block produced using the pattern shown in Fig. 2D; Figs. 9A to 9C are diagrams illustrating a sixth example of the pattern by units of a functional block produced using the pattern shown in Fig. 2D; Figs. 10A to 10C are diagrams illustrating a seventh example of the pattern by units of a functional block produced using the pattern shown in Fig. 2D; Figs. 11A to 11C are diagrams illustrating an eighth example of the pattern by units of a functional block produced using the pattern shown in Fig. 2D; Figs. 12A to 12C are diagrams illustrating a ninth example of the pattern by units of a functional block produced using the pattern shown in Fig. 2D; Figs. 13A to 13C are diagrams illustrating a tenth example of the pattern by units of a functional block produced using the pattern shown in Fig. 2D; Fig. 14 is a pattern diagram illustrating a modification of the pattern shown in Fig. 2D; and Fig. 15 is a pattern diagram illustrating another modification of the pattern shown in Fig. 2D. DESCRIPTION OF THE PREFERRED EMBODIMENTS Before explaining the preferred embodiment of the present invention, the constitution of the transistor cell or pattern will be explained with reference to Fig. 1, which illustrates a typical example thereof. In Fig. 1, reference V DD denotes a pattern of a higher voltage power supply line and reference V SS denotes a pattern of a lower voltage power supply line. Illustration (a) shows a transistor pattern corresponding to one basic cell (shown by a dot and dash line). In illustration (b), a hatched portion A represents a gate region of the transistor. Also, hatched portions B P and B N in illustration (c) represent a P-type impurity region and an N-type impurity region, respectively, constituting a source/drain (S/D) region of the transistor. Illustration (d) shows a region on which the transistors are formed. Namely, hatched portions C P1 and C P2 represent P-channel transistors and hatched portions C N1 and C N2 represent N-channel transistors. Thus, in the example of Fig. 1, one basic cell is constituted by a pair of P-channel transistors and a pair of N-channel transistors. Next, a preferred embodiment according to the present invention will be explained with reference to Figs. 2A to 2D, which show the process of forming the common pattern based on which various patterns by units of a functional block are constituted. Figure 2A illustrates an example of the transistor pattern formed by means of the diffusion process (first process). In the illustration, reference TR denotes a transistor region; reference G a gate region; reference S/D a source/drain (S/D) region; and reference F a field region, respectively. Two transistors connected by the common gate region, i.e., P-channel transistorQ P and N-channel transistorQ N , constitute one basic cell. Namely, in the first process, the transistor regions (patterns) TR are arranged with units of the cell in an array on a semiconductor chip. After this, a first insulation layer (not shown) is formed over all the transistor regions. Figure 2B illustrates an example of the first Al wiring pattern LA formed by means of a second process and applied to the pattern of Fig. 2A. In the illustration, the portion shown by a broken line represents the transistor region and the portion shown by a single solid line represents the first wiring pattern LA. Especially, the pattern LA indicated by reference V DD represents the higher voltage power supply line (5V) and the pattern LA indicated by referenceV SS represents the lower voltage power supply line (OV). In the second process, the first wiring patterns LA extending in parallel at a space therebetween with units of three lines are formed with units of a predetermined length in a discontinuous form so that they pass through regions corresponding to the transistor regions. Also, the wiring patterns serving as the power supply line V DD and V SS are formed so that they do not intersect the first wiring patterns LA and pass through regions corresponding to the transistor regions along the longitudinal direction. Figure 2C illustrates an example of the first contact hole pattern NA formed by means of a third process and applied to the pattern of Fig. 2B. In the illustration, the portion shown by the broken line represents the transistor region; the portion shown by the single solid line represents the first wiring pattern LA; and the portion shown by a cross mark represents the first contact hole pattern NA. In the third process, the first contact hole patterns NA are formed at predetermined positions in the first insulation layer so that gate regions G and source/drain regions S/D of the transistor regions TR are connected to the first wirings LA. After this, a second insulation layer (not shown) is formed over all the first wirings and the first contact holes. Therefore, the pattern is formed in which three terminals of the transistor, i.e., the gate, source and drain, are fixedly connected via the first contact holes NA to the first wirings LA. The circuit constitution equivalently showing the pattern of Fig. 2C is shown in Fig. 3. In the illustration, reference P 1 corresponds to the gate and references P 2 and P 3 correspond to the source and drain, respectively. Figure 2D illustrates an example of the second Al wiring pattern LB formed by means of a fourth process and applied to the pattern of Fig. 2C. In the illustration, the portion shown by the broken line represents the transistor region; the portion shown by the single solid line represents the first wiring pattern LA; the portion shown by the cross mark represents the first contact hole pattern NA; and the portion shown by a pair of solid lines represents the second wiring pattern LB. In the fourth process, the second wiring patterns LB having the same forms as the first wiring patterns LA are formed so that they constitute a mesh-like arrangement in combination with the first wirings. Next, various patterns formed by units of a functional block produced using the common pattern shown in Fig. 2D will be explained with reference to Figs. 4A to 13C. Figures 4A to 4C illustrate a constitution of an inversion circuit constituted by a single inverter. In Fig. 4A, the portion shown by a round black mark indicates the second contact hole pattern NB. Namely, the first wiring pattern and the second wiring pattern are connected at this portion (NB). Figure 4B shows the pattern of Fig. 4A in the form of the equivalent circuit and Fig. 4C shows the circuit of Fig. 4B in the form of the gate indication. In each figure, the corresponding portion or element is given the identical reference. Figures 5A to 5C illustrate a constitution of the inversion circuit constituted by two inverters; Figs. 6A to 6C illustrate a constitution of a two-input type NAND gate; Figs. 7A to 7C illustrate a constitution of a three-input type NAND gate; Figs. 8A to 8C illustrate a constitution of a four-input type NAND gate; Figs. 9A to 9C illustrate a constitution of a three-input gate circuit constituted by a two-input type AND gate and a two-input type NOR gate; Figs. 10A to 10C illustrate a constitution of a four-input gate circuit constituted by a three-input type AND gate and a two-input type NOR gate; Figs. 11A to 11C illustrate a constitution of a four-input gate circuit constituted by a pair of two-input type AND gates and a two-input type NOR gate; Figs. 12A to 12C illustrate a constitution of a four-input gate circuit constituted by a two-input type AND gate and a three-input type NAND gate; and Figs. 13A to 13C illustrate a constitution of a four-input gate circuit constituted by a two-input type OR gate, a two-input type AND gate and a two-input type NOR gate. As explained above, it is possible to constitute a desired LSI by suitably disposing the second contact hole patterns NB at some of the intersections or abutments of the first wiring patterns LA and the second wiring patterns LB and changing the form of the disposition thereof in accordance with demanded conditions of a given circuit. Namely, since three kinds of patterns of the first wirings LA, first contact holes NA, and second wirings LB among four kinds of patterns which have been to be heretofore changed according to the user's demands are fixedly prepared in the same manner as in the transistor pattern, the entire process can be simplified, compared with the prior art process. This leads to a reduction of the turnaround time and thus contributes to an improvement of the yield. Although, in the disclosed and described embodiment, the first wiring patterns LA serving as the power supply line V DD or V SS are arranged only along the longitudinal direction, the form of the arrangement of the power supply line is not restricted thereto. Namely, it is possible to easily modify the form of the arrangement of the power supply line by suitably changing the fixed wiring patterns (LA,LB) in accordance with the conditions of the LSI to be constituted. For example, as shown in Fig. 14, each of the first wiring pattern LA and second wiring pattern LB serving as the power supply line may be arranged on every second line along the longitudinal direction and the transverse direction, respectively. Also, as shown in Fig. 15, each of the first wiring pattern LA and second wiring pattern LB may be arranged on every third line along the longitudinal direction and only the second wiring pattern LB may be arranged along the transverse direction. Also, in some cases, it is also possible to utilize a portion of the first wiring pattern LA or second wiring pattern LB as the power supply line without taking the trouble to provide the wiring pattern for private use of the power supply line.

Claims: A method of forming a semiconductor integrated circuit using a master slice approach comprising the steps of: forming a plurality of transistor regions (TR) with units of a predetermined number in an array on a semiconductor chip and then forming a first insulation layer over all said transistor regions; forming a first wiring pattern (LA), comprising a plurality of first lines extending in parallel and being arranged in groups of three lines spaced apart from each other, said first lines consisting of discontinuous portions of a predetermined length and being arranged so that adjacent portions of the three lines of each group form separate units of said predetermined length, so that said first pattern (LA) passes through regions corresponding to said transistor regions; forming first contact holes (NA) at predetermined positions in said first insulation layer so that gate regions (G) and source/drain regions (S/D) of said transistor regions are connected to said first lines and then forming a second insulation layer over all said first wiring pattern (LA) and said first contact holes (NA); and forming a second wiring pattern (LB), comprising a plurality of second lines extending in parallel and being arranged in groups of three lines spaced apart from each other, said second lines consisting of discontinuous portions of a predetermined length and being arranged so that adjacent portions of the three lines of each group form separate units of said predetermined length, the second wiring pattern (LB) having the same form as the first wiring pattern (LA), so that said second wiring pattern (LB) constitutes a mesh-like arrangement in combination with said first wiring pattern (LA), said arrangement of said first and second wiring patterns (LA, LB) formed on regions corresponding to said transistor regions (TR) being the same as said arrangement of said first and second wiring patterns (LA, LB) formed on regions corresponding to a field region (F) other than said transistor regions, and forming second contact holes (NB) in said second insulation layer using a pattern mask programmable in accordance with demanded conditions of a given circuit so that said second contact holes connect said second wiring pattern (LB) to said first wiring pattern (LA). A method as set forth in claim 1, wherein the step of forming said first wiring pattern (LA) includes a step of forming wirings for power supply lines so that they extend in a continuous form along a first direction of said chip. A method as set forth in claim 2, wherein the step of forming said second wiring pattern (LB) includes a step of forming wirings for power supply lines so that they extend in a continuous form along said first direction and a second direction perpendicular to said first direction. A method as set forth in claim 3, wherein said wirings for power supply lines formed in the step of forming said first wiring pattern (LA) extend in a continuous form along said second direction.

Inventors: OHE RYOICHI, OHE, RYOICHI
Applicants: FUJITSU LTD, FUJITSU LIMITED
Application year: 1989
Main classification: H01L27
IPC codes: H01L27, H03K19, H01L21