処理中

しばらくお待ちください...

設定

設定

出願の表示

1. US20120168875 - Semiconductor device

注意: このテキストは、OCR 処理によってテキスト化されたものです。法的な用途には PDF 版をご利用ください。

[ EN ]

BACKGROUND

      1. Technical Field
      The present invention relates to a semiconductor device provided with a well potential supply region for supplying power to a well region.
      2. Background Art
      In a semiconductor device of the related art, there is provided a well potential supply region for supplying power to a well region in the vicinity of an active transistor for the purpose of controlling well potential, in other words, for the purpose of preventing latch-up. Furthermore, the “active transistor” refers to a transistor that contributes to a desired function of a circuit using the operation characteristic of the transistor.
       FIG. 12 is a diagram showing an example of a layout of a semiconductor device of the related art, in which a well potential supply region is provided. In the configuration of FIG. 12, standard cell arrays in which a plurality of standard cells are disposed in the horizontal direction of the drawing are disposed by being arranged in the vertical direction of the drawing. In addition, in the standard cell array in the center, well potential supply cell VSC is inserted. VSCN is a well potential supply region (TAP region) for supplying well potential to an N-type well, in which N-type impurities are implanted and VSCP is a well potential supply region for supplying well potential to a P-type well, in which P-type impurities are implanted.
      Refer to Unexamined Japanese Patent Publication No. 2008-235350, Unexamined Japanese Patent Publication No. 2007-12855, Unexamined Japanese Patent Publication No. 2001-148464, and Unexamined Japanese Patent Publication No. 2009-32961, for example.

SUMMARY

      As semiconductor devices have progressed in miniaturization in recent years, the influence of an optical proximity effect caused by diffracted light increases when a gate is exposed. For this reason, there occurs a problem in that the influence of the optical proximity effect significantly differs depending on the state of peripheral gate patterns, and unevenness in the gate length occurs.
      In order to take measures for the problem, it is necessary to secure regularity in the shapes of the gate patterns in the periphery of a target gate. In addition, it is necessary to maintain regularity in the shapes not only of the gate patterns arranged in the lateral direction of the target gate, but also of the gate patterns arranged in the longitudinal direction thereof.
      However, when well potential supply cells are disposed in the related art, it is not possible to maintain regularity in the shapes of the gate patterns arranged in the lateral and longitudinal directions of the target gate. In the layout of FIG. 12 for example, by inserting well potential supply cell VSC, a gate is not closely disposed in the lower side of gate electrode GT 5 and dummy gates GT 4 and GT 6 of the upper standard cell array, in addition, a gate is not closely disposed in the upper side of gate electrodes GB 4, GB 5, and GB 6 of the lower standard cell array. In addition, a gate is not closely disposed in the right and left sides of respective gate electrodes GM 3 and GM 7. As such, by inserting the well potential supply cells VSC, regularity in the shapes of the peripheral gate patterns is not maintained.
      Therefore, in a semiconductor device of the related art, it is necessary to dispose standard cells having active transistors avoiding the periphery of well potential supply cells VSC, in order to maintain regularity in the shapes of the gate patterns. In this case, however, an increase in the layout area of the semiconductor device is induced, which is not favorable.
      Taking the above problem into consideration, the present invention aims to realize a semiconductor device having a well potential supply area while reliably suppressing unevenness in a gate length caused by the optical proximity effect without increasing the layout area.
      According to an aspect of the present invention, there is provided a semiconductor device that includes a plurality of cell arrays, in which a plurality of gates extending in a first direction are arranged and disposed in a second direction orthogonal to the first direction, being arranged and disposed in the first direction, each of the plurality of cell arrays includes a first conductive type well region and a second conductive type well region which are formed below the gates and respectively extend in the second direction, a first cell array that is one of the plurality of cell arrays includes a first well potential supply region into which impurities of the same conductive type as that of the first conductive type well region are implanted in the first conductive type well region, first and second adjacent gates that are respectively disposed in both sides of the first well potential supply region in the second direction, a third adjacent gate that is disposed adjacent to the first adjacent gate in the opposite side to the first well potential supply region, and a fourth adjacent gate that is disposed adjacent to the second adjacent gate in the opposite side to the first well potential supply region, the first to the fourth adjacent gates are disposed at the same pitch in the second direction, and a first adjacent cell array adjacent to the first cell array in the first direction among the plurality of cell arrays includes four gates each of which is opposed to the first to the fourth adjacent gates in the first direction.
      According to the aspect, the first well potential supply region is provided in the first conductive type well region of the first cell array. In addition, the first and the second adjacent gates disposed in the both sides of the first well potential supply region in the second direction and the third and the fourth adjacent gates disposed in further both sides thereof are disposed in the second direction at the same pitch. Furthermore, the first adjacent cell array adjacent to the first cell array in the first direction includes the four gates each of which is opposed to the first to the fourth adjacent gates in the first direction. In other words, regularity in the shapes of the gate patterns in the periphery of the first well potential supply region is maintained. Therefore, since it is possible to avoid the influence of an optical proximity effect differing depending on the gate patterns, it is possible to suppress an increase in the layout area resulting from the provision of the well potential supply region while reliably suppressing unevenness in the gate lengths.
      According to another aspect of the present invention, there is provided a semiconductor device that includes a plurality of cell arrays, in which a plurality of gates extending in a first direction are arranged and disposed in a second direction orthogonal to the first direction, being arranged and disposed in the first direction, the plurality of cell arrays respectively include a first conductive type well region and a second conductive type well region that are formed below the gates and respectively extend in the second direction, and a first cell array that is one of the plurality of cell arrays includes a first well potential supply region into which impurities of the same conductive type as that of the first conductive type well region are implanted in the first conductive type well region, and a first gate disposed over the first well potential supply region.
      According to the aspect, the first well potential supply region is provided in the first conductive type well region of the first cell array. In addition, the first gate is disposed over the first well potential supply region. With this configuration, it is possible to dispose the plurality of gates including the first gate in the second direction at the same pitch, and possible to be opposed to other gates in the first direction. In other words, it is possible to maintain regularity in the shapes of the gate patterns in the periphery of the first well potential supply region. Therefore, since it is possible to avoid the influence of an optical proximity effect differing depending on the gate patterns, it is possible to suppress an increase in the layout area resulting from the provision of the well potential supply region while reliably suppressing unevenness in the gate lengths.

Advantageous Effects of the Invention

      According to the present invention, even when a well potential supply area is disposed, since it is possible to maintain regularity in the shapes of the peripheral gate patterns thereof, an increase in the layout area resulting from providing the well potential supply area can be suppressed while reliably suppressing unevenness in the gate length.

BRIEF DESCRIPTION OF DRAWINGS

       FIG. 1 is an example of the layout structure of a tap cell according to a first exemplary embodiment.
       FIG. 2 is another example of the layout structure of the tap cell according to the first exemplary embodiment.
       FIG. 3 is an example of the layout configuration of a semiconductor device using the tap cell of FIGS. 1 and 2.
       FIG. 4A is a diagram showing the plane structure of the tap cell.
       FIG. 4B is a diagram showing the cross-sectional structure of FIG. 4A.
       FIG. 4C is a diagram showing the cross-sectional structure of FIG. 4A.
       FIG. 4D is a diagram showing the cross-sectional structure of FIG. 4A.
       FIG. 5A is a diagram showing the plane structure of the tap cell.
       FIG. 5B is a diagram showing the cross-sectional structure of FIG. 5A.
       FIG. 6 is an example of the layout structure of a tap cell according to a second exemplary embodiment.
       FIG. 7 is an example of the layout structure of a semiconductor device using a transistor-type well potential supply region shown in FIG. 6.
       FIG. 8 is another example of the layout structure of the semiconductor device.
       FIG. 9 is another example of the layout structure of the semiconductor device.
       FIG. 10 is another example of the layout structure of the semiconductor device.
       FIG. 11 is another example of the layout structure of the semiconductor device.
       FIG. 12 is an example of the layout of a semiconductor device.

DESCRIPTION OF EMBODIMENTS

      Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Furthermore, in the present description, a “dummy gate” refers to a gate that does not constitute a transistor. In addition, a gate that functions as a gate of an active transistor refers to a “gate electrode”. Furthermore, simply a “gate” refers to both the “dummy gate” and the “gate electrode”.

First Exemplary Embodiment

       FIG. 1 is a drawing showing an example of the layout structure of a tap cell according to a first exemplary embodiment. Herein, a “tap cell” refers to a cell having a potential supply region to a well. In the layout structure of FIG. 1, tap cell 1 is closely disposed between logic cells 5 a and 5 b constituting an inverter.
      In FIG. 1, tap cell 1 includes N-type impurity diffusion region 11 n formed in N-type well region NW and P-type impurity diffusion region 11 p formed in P-type well region PW. Desired well potential is supplied from N-type impurity diffusion region 11 n to N-type well region NW via contacts and wiring. Desired well potential is supplied from P-type impurity diffusion region 11 p to P-type well region PW via the contacts and wiring. In other words, N-type impurity diffusion region 11 n and P-type impurity diffusion region 11 p constitute a well potential supply region (TAP region).
      Logic cells 5 a and 5 b respectively include PMOS transistors TPa and TPb formed in N-type well region NW and NMOS transistors TNa and TNb formed in P-type well region PW.
      In addition, dummy gates 12 a and 12 b are respectively disposed between tap cell 1 and logic cells 5 a and 5 b. In addition, dummy gates 13 a and 13 b are respectively disposed in the boundaries of logic cells 5 a and 5 b in the opposite side to tap cell 1.
      By disposing the dummy gates as above, a plurality of gates (including the dummy gates) extending in the vertical direction are laid out in the horizontal direction substantially at fixed pitch P, as shown in FIG. 1. In other words, by employing the layout structure of tap cell 1 as in FIG. 1, it is possible to secure regularity in the shapes of gate patterns even when tap cell 1 is disposed between logic cells 5 a and 5 b.
       FIG. 2 is a diagram showing another example of the layout structure of the tap cell according to the first exemplary embodiment. In the layout structure of FIG. 2, tap cell 2 is closely disposed between logic cells 5 a and 5 b constituting an inverter. The layout structure of logic cells 5 a and 5 b is the same as that of FIG. 1.
      In FIG. 2, tap cell 2 includes two N-type impurity diffusion regions 21 n and 22 n formed in N-type well region NW and two P-type impurity diffusion regions 21 p and 22 p formed in P-type well region PW. Desired well potential is supplied from N-type impurity diffusion regions 21 n and 22 n to N-type well region NW via contacts and wiring. Desired well potential is supplied from P-type impurity diffusion regions 21 p and 22 p to P-type well region PW via the contacts and wiring. In other words, two N-type impurity diffusion regions 21 n and 22 n and two P-type impurity diffusion regions 21 p and 22 p constitute a well potential supply region (TAP region).
      In addition, dummy gates 23 a and 23 b are respectively disposed between tap cell 2 and logic cells 5 a and 5 b. Furthermore, dummy gate 23 c is disposed between N-type impurity diffusion regions 21 n and 22 n and P-type impurity diffusion regions 21 p and 22 p.
      By disposing the dummy gates as above, a plurality of gates (including the dummy gates) extending to the vertical direction are laid out in the horizontal direction substantially at fixed pitch P, as shown in FIG. 2. In other words, by employing the layout structure of tap cell 2 as in FIG. 2, it is possible to secure regularity in the shapes of gate patterns even when tap cell 2 is disposed between logic cells 5 a and 5 b.
       FIG. 3 is an example of the layout structure of a semiconductor device using the tap cells shown in FIGS. 1 and 2. In the layout of FIG. 3, cell arrays A 1 and A 2 in which a plurality of gates extending in the vertical direction (first direction) are disposed by being arranged in the horizontal direction (second direction) are arranged in the vertical direction. In cell arrays A 1 and A 2, P-type well region PW and N-type well region NW extending in the horizontal direction are respectively formed below gates. Furthermore, in cell array A 2, P-type well region PW and N-type well region NW are flipped so as to make N-type well regions NW of cell arrays A 1 and A 2 adjacent to each other.
      In the layout structure of FIG. 3, tap cells 1A, 1B, 1C, and 1D having the same structure as tap cell 1 shown in FIG. 1 and tap cells 2A, 2B, 2C, and 2D having the same structure as tap cell 2 shown in FIG. 2 are disposed.
      Herein, focus on N-type impurity diffusion region 14 n in tap cell 1A disposed in cell array A 1. N-type impurity diffusion region 14 n functions as a well potential supply region that supplies well potential to N-type well region NW of cell array A 1. In addition, dummy gates 15 a and 15 b are respectively disposed, as first and second adjacent gates, in both sides of N-type impurity diffusion region 14 n in the horizontal direction as a first well potential supply region. Gate electrode 15 c is closely disposed as a third adjacent gate in the opposite side to N-type impurity diffusion region 14 n in the side of dummy gate 15 a, and gate electrode 15 d is closely disposed as a fourth adjacent gate in the opposite side to N-type impurity diffusion region 14 n in the side of dummy gate 15 b.
      In addition, gate electrode 15 c, dummy gates 15 a and 15 b, and gate electrode 15 d are disposed in the horizontal direction at the same pitch P. Furthermore, cell array A 2 as a first adjacent cell array includes four gates 15 g, 15 e, 15 f, and 15 h that are respectively opposed (at interval S) to gate electrode 15 c, dummy gates 15 a and 15 b, and gate electrode 15 d of cell array A 1 in the vertical direction. In other words, the pattern of a total of four gates, two of which are adjacent in the horizontal direction, has regularity in the shapes in the focused N-type impurity diffusion region 14 n.
      In addition, focus on N-type impurity diffusion region 16 n in tap cell 2C disposed in cell array A 2. N-type impurity diffusion region 16 n functions as a well potential supply region that supplies well potential to N-type well region NW of cell array A 2. In addition, dummy gates 17 a and 17 b are respectively disposed, as the first and the second adjacent gates, in both sides of N-type impurity diffusion region 16 n in the horizontal direction as the first well potential supply region. Gate electrode 17 c is closely disposed as the third adjacent gate in the opposite side to N-type impurity diffusion region 16 n in the side of dummy gate 17 a, and gate electrode 17 d is closely disposed as the fourth adjacent gate in the opposite side to N-type impurity diffusion region 16 n in the side of dummy gate 17 b. Furthermore, N-type impurity diffusion region 18 n is formed between dummy gate 17 b and dummy gate 17 d as a second well potential supply region.
      In addition, gate electrode 17 c, and dummy gates 17 a, 17 b, and 17 d are disposed in the horizontal direction at the same pitch P. Furthermore, cell array A 1 as the first adjacent cell array includes four gates 17 g, 17 e, 17 f, and 17 h that are respectively opposed to gate electrode 17 c, and dummy gates 17 a, 17 b, and 17 d of cell array A 2 in the vertical direction. In other words, the pattern of a total of four gates, two of which are adjacent in the horizontal direction, has regularity in the shapes in the focused N-type impurity diffusion region 16 n.
      Even when the well potential supply regions are disposed in such layouts, since it is possible to maintain regularity in the shape of the gate pattern around the region, it is possible to avoid the influence of an optical proximity effect differing from the gate patterns. Therefore, it is possible to suppress an increase in the layout area caused by the provision of the well potential supply regions while reliably suppressing unevenness in the gate length.
      Furthermore, herein, description is provided focusing on the N-type impurity diffusion region that supplies well potential to the N-type well region, but the same configuration can be realized for the P-type impurity diffusion region that supplies well potential to the P-type well region, and thus the same operational effect is obtained.
      Herein, “gates are disposed at the same pitch P” does not necessarily mean the pitch is perfectly the same, but the gates may be disposed substantially at the same pitch, allowing a certain degree of variation. For example, a variation up to about a half of pitch P (=P/2) is allowed. Alternatively, a variation up to gate width Lg is allowed.
      In addition, the four gates adjacent to the well potential supply region and the four gates opposed thereto are preferably disposed substantially with the same interval. Furthermore, it may be possible that the gates are connected to the opposing gates forming one body as are dummy gates 17 a, 17 b, and 17 d in tap cell 2C.
      In addition, it may be possible that a well potential supply region is formed with a well potential supply region of the same conductive type in an adjacent cell array as one body. For example, N-type impurity diffusion region 16 n in tap cell 2C may be formed as one body with N-type impurity diffusion region 19 n as a third well potential supply region in tap cell 2A of cell array A 1 as shown by dashed lines. By forming as above, impurity implantation for forming the well potential supply region becomes easier.
      Furthermore, in the configurations of FIGS. 1 to 3, it is preferable that the widths of respective gates in the horizontal direction be the same in addition to the gates disposed at the same pitch P.
      In addition, FIGS. 1 to 3 show that the sizes of the well potential supply regions in the vertical direction are the same as the gate widths (the width of the diffusion region) of adjacent transistors, but the invention is not limited thereto, and the sizes may be different from the gate widths of the transistors.
      In addition, in FIGS. 1 to 3, each gate extends over the boundary of N-type well region NW and P-type well region PW, but may be disposed by being divided at the boundary. Furthermore, it may be possible that gates are divided and disposed in N-type well region NW or P-type well region PW after taking the influence of a proximity effect into consideration.
      In addition, a well potential supply region may be disposed by being interposed between gates, and the size of the region in the vertical direction and the horizontal direction is not particularly restricted.
       FIG. 4A is the same plane diagram as FIG. 1, FIGS. 4B and 4C are diagrams showing the cross-sectional structure of FIG. 4A, and FIG. 4D is a diagram showing the cross-sectional structure of FIG. 4A. When the structure of the tap cell is employed as in FIG. 1, the widths of well potential supply regions 11 n and 11 p in the horizontal direction are minute, there is a possibility that impurities are not necessarily well implanted. In other words, as shown in FIG. 4B, ideally, it is preferable that impurities of the same conductive type (N-type in the drawing) as that of a well region be implanted into a well potential supply region interposed between dummy gates. In an actual manufacturing process, however, as shown in FIGS. 4C and 4D, impurities of a different conductive type (P-type in the drawings) that are implanted in an adjacent diffusion region are implanted into the well potential supply region, and for that reason, there is a possibility that the well potential supply regions are not properly formed between the dummy gates.
       FIG. 5A is the same plane diagram as in FIG. 2, and FIG. 5B is a diagram showing the cross-sectional structure of FIG. 5A. When the structure of the tap cell is employed as in FIG. 2, even in a case where impurities of a different conductive type (P-type in the drawing) that are implanted the adjacent diffusion region are implanted to the well potential supply regions as shown in FIG. 5B, the well potential supply regions of the same conductive type (N-type in the drawing) as that of the well regions are formed between the dummy gates.

Second Exemplary Embodiment

       FIG. 6 is a diagram showing an example of the layout structure of a tap cell according to a second exemplary embodiment. In the layout structure of FIG. 6, tap cell 3 is closely disposed between logic cells 5 a and 5 b constituting an inverter. The layout structure of logic cells 5 a and 5 b is the same as in FIG. 1.
      In FIG. 6, tap cell 3 includes N-type impurity diffusion region 31 n formed in N-type well region NW and P-type impurity diffusion region 31 p formed in P-type well region PW. Desired well potential is supplied from N-type impurity diffusion region 31 n to N-type well region NW via contacts and wiring. Desired well potential is supplied from P-type impurity diffusion region 31 p to P-type well region PW via the contacts and wiring. In other words, N-type impurity diffusion region 31 n and P-type impurity diffusion region 31 p constitute a well potential supply region (TAP region).
      In addition, dummy gates 32 a and 32 b are respectively disposed between tap cell 3 and logic cells 5 a and 5 b. Furthermore, dummy gate 32 c is disposed over N-type impurity diffusion region 31 n and P-type impurity diffusion region 31 p. In other words, N-type impurity diffusion region 31 n and P-type impurity diffusion region 31 p form a so-called transistor-type well potential supply region.
      By disposing the dummy gates as above, a plurality of gates (including the dummy gates) extending in the vertical direction are laid out in the horizontal direction substantially at fixed pitch P, as shown in FIG. 6. In other words, by employing the layout structure of tap cell 3 as shown in FIG. 6, even when tap cell 3 is disposed between logic cells 5 a and 5 b, it is possible to secure regularity in the shape of gate patterns.
       FIG. 7 is an example of the layout structure of a semiconductor device using the transistor-type well potential supply region shown in FIG. 6. In the layout of FIG. 7, cell arrays B 1, B 2, and B 3, in which a plurality of gates extending in the vertical direction (first direction) are arranged and disposed in the horizontal direction (second direction), are arranged and disposed in the vertical direction. In cell arrays B 1, B 2, and B 3, P-type well regions PW and N-type well regions NW extending in the horizontal direction are respectively formed below the gates. Furthermore, in cell array B 2, P-type well region PW and N-type well region NW are flipped so as to make N-type well regions NW of cell arrays B 1 and B 2 adjacent to each other and make P-type well regions PW of cell arrays B 2 and B 3 adjacent to each other.
      In the layout structure of FIG. 7, as a first transistor-type well potential supply region, P-type impurity diffusion regions 33 p and 34 p and N-type impurity diffusion region 33 n are provided. P-type impurity diffusion region 33 p performs power-supply to P-type well region PW of cell array B 1, N-type impurity diffusion region 33 n performs power-supply to N-type well region NW of cell array B 1, and P-type impurity diffusion region 34 p performs power-supply to P-type well region PW of cell array B 2. In addition, dummy gate 34 a as a first gate on P-type impurity diffusion regions 33 p, dummy gate 34 b as the first gate on N-type impurity diffusion region 33 n, and dummy gate 34 c as the first gate on P-type impurity diffusion regions 34 p are respectively disposed.
      With the layout as above, since it is possible to maintain regularity in the shape of gate patterns around well potential supply regions even when the regions are disposed, it is possible to avoid the influence of an optical proximity effect differing depending on the gate patterns. Therefore, it is possible to suppress an increase in the area resulting from the provision of the well potential supply regions for controlling well potential and preventing latch-up while reliably suppressing unevenness in the gate lengths.
      Furthermore, it may be possible that the gates disposed on the transistor-type well potential supply region may be gate electrodes functioning as gates of active transistors. In the layout of FIG. 7, on P-type impurity diffusion region 35 p as the first well potential supply region that performs power-supply to P-type well region PW of cell array B 3, gate electrode 36 is disposed as the first gate extending from active transistor TN 1 below P-type impurity diffusion region 35 p.

Another Example of Layout Structure

Example 1

       FIG. 8 is another example of the layout structure of the semiconductor device. In the layout of FIG. 8, cell arrays C 1, C 2, and C 3, in which a plurality of gates extending in the vertical direction are arranged and disposed in the horizontal direction, are arranged and disposed in the vertical direction in the same manner as in FIG. 7. In cell arrays C 1, C 2, and C 3, P-type well regions PW and N-type well regions NW extending in the horizontal direction are respectively formed below the gates. Furthermore, in cell array C 2, P-type well region PW and N-type well region NW are flipped so as to make N-type well regions NW of cell arrays C 1 and C 2 adjacent to each other and make P-type well regions PW of cell arrays C 2 and C 3 adjacent to each other.
      One of the characteristics of the layout structure of FIG. 8 is P-type impurity diffusion region 41 p and N-type impurity diffusion region 41 n. P-type impurity diffusion region 41 p performs power-supply to P-type well region PW of cell array C 1 and N-type impurity diffusion region 41 n performs power-supply to N-type well region NW of cell array C 1. In addition, both of P-type impurity diffusion region 41 p and N-type impurity diffusion region 41 n are disposed below dummy gates 42 a and 42 b in both sides of the regions in an overlapping manner. Since it is possible to increase the widths of the impurity diffusion regions in the horizontal direction by allowing such disposition, an effect is obtained in which implantation of impurities becomes easier in the manufacturing process.
      In addition, P-type impurity diffusion region 43 p that performs power-supply to P-type well region PW of cell array C 3 is disposed under dummy gate 44 a in one side of the region in an overlapping manner. Similarly, N-type impurity diffusion region 43 n that performs power-supply to N-type well region NW of cell array C 3 is disposed under dummy gate 44 b in one side of the region in an overlapping manner. Even in the disposition as above, it is possible to increase the widths of the impurity diffusion regions in the horizontal direction.

Example 2

       FIG. 9 is another example of the layout structure of the semiconductor device. In the layout of FIG. 9, cell arrays D 1, D 2, and D 3 in which a plurality of gates extending in the vertical direction are arranged and disposed in the horizontal direction are arranged and disposed in the vertical direction in the same manner as in FIG. 7. In cell arrays D 1, D 2, and D 3, P-type well regions PW and N-type well regions NW extending in the horizontal direction are respectively formed below gates. Furthermore, in cell array D 2, P-type well region PW and N-type well region NW are flipped so as to make N-type well regions NW of cell arrays D 1 and D 2 adjacent to each other, and to make P-type well regions PW of cell arrays D 2 and D 3 adjacent to each other.
      One of the characteristics of the layout structure of FIG. 9 is that impurities of a different conductive type from that of the well regions are implanted into either of the diffusion regions interposing the dummy gates in the transistor-type well potential supply region. For example, dummy gate 46 is disposed by being interposed between N-type impurity diffusion region 45 n and P-type impurity diffusion region 45 p in N-type well region NW of cell array D 1. In addition, dummy gate 48 is disposed by being interposed between P-type impurity diffusion region 47 p and N-type impurity diffusion region 47 n in P-type well region PW of cell array D 2.
      For example, by disposing P-type impurity diffusion region 45 p, it is possible to reliably implant impurities into the P-type impurity diffusion regions that serve as drains or sources of PMOS transistors disposed in the right side thereof without causing an operational problem. By setting either of the diffusion regions interposing the dummy gate to an impurity diffusion region of a different conductive type from that of the well region in the transistor-type well potential supply region, it is possible to reliably form a diffusion region of an adjacent transistor thereto.

Example 3

      The description hitherto shows an example in which adjacent gates disposed in both sides of a well potential supply region are dummy gates. In the present exemplary embodiment, however, it may be possible that adjacent gates disposed in both sides of a well potential supply region are gates functioning as gate electrodes of active transistors.
       FIGS. 10 and 11 are other examples of the layout structure of the semiconductor device. In the layout of FIG. 10, cell arrays E 1 and E 2 in which a plurality of gates extending in the vertical direction are arranged and disposed in the horizontal direction are arranged and disposed in the vertical direction. In cell array E 1 and E 2, P-type well regions PW and N-type well regions NW extending in the horizontal direction are respectively formed below gates. Furthermore, in cell array E 2, P-type well region PW and N-type well region NW are flipped so as to make N-type well regions NW of cell arrays E 1 and E 2 adjacent to each other. Cell arrays F 1 and F 2 are disposed also in the layout of FIG. 11 in the same manner.
      For example, in FIG. 10, gate electrodes 52 a and 52 b are adjacent to each other, as first and second adjacent gates functioning as gates of active transistors, in P-type impurity diffusion region 51 p that serves as a first well potential supply region. In addition, in FIG. 11, gate electrode 54 a as the first adjacent gate functioning as the gate of the active transistor and dummy gate 54 b as the second adjacent gate are adjacent to each other in N-type impurity diffusion region 53 n that serves as the first well potential supply region.
      Furthermore, in the above-described layout of the semiconductor device, impurity diffusion regions of the same conductive type as that of the well regions, which extend in the horizontal direction may be provided between the cell arrays. In the layout of FIG. 7, for example, it may be possible that an N-type impurity diffusion region extending in the horizontal direction is provided between cell arrays B 1 and B 2, and a P-type impurity diffusion region extending in the horizontal direction is provided between cell arrays B 2 and B 3. For example, by using the impurity diffusion regions provided between the cell arrays in power-supply to the well regions, it is possible to further stabilize the potential of the well regions.
      Alternatively, in the above-described layout of the semiconductor device, an impurity diffusion region of a different conductive type from that of a well region, which extends in the horizontal direction, may be provided between cell arrays. For example, it may be possible that, in the layout of FIG. 7, a P-type impurity diffusion region extending in the horizontal direction is provided between cell arrays B 1 and B 2, and an N-type impurity diffusion region extending in the horizontal direction is provided between cell arrays B 2 and B 3. By using the impurity diffusion regions provided between the cell arrays in, for example, the supply of power source potential or substrate potential, it is possible to further stabilize source potential of a transistor.
      In the present invention, since a semiconductor device having well potential supply regions can be realized while reliably suppressing unevenness in the gate lengths caused by the optical proximity effect without increasing the layout area, the invention is effective in, for example, improving the yield and miniaturization of a semiconductor chip.