JPH065714A - Multilayer wiring structure and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Object] In a multilayer wiring structure, when connecting the first wiring of the lower layer and the third wiring of the upper layer, the second wiring of the middle layer can be minimized without touching. A contact hole having the design dimension of is formed to realize high-density mounting of wiring. [Structure] A first interlayer insulating film 13 covering a first wiring 12 on a substrate 11 is formed, and second wirings 14 and 15 having insulating films 16 and 17 formed on the upper surface are formed into a first interlayer insulating film. Form on 13. Each second
A second interlayer insulating film 18 is formed to cover the wirings 14 and 15 and the insulating films 16 and 17, and the first and second interlayers between the second wirings 14 and 15 are formed on the first wiring 12. A contact hole 19 is provided in the insulating films 13 and 18, and an insulating sidewall 20 is formed on the side wall of the contact hole 19.
The third wiring 21 connected to the first wiring 12 through the contact hole 19 is formed on the second interlayer insulating film 18. Alternatively, a conductive plug (not shown) is provided in the contact hole 19 and a third wiring 21 connected to the plug is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring structure and its manufacturing method.

[0002]

2. Description of the Related Art In order to connect the wiring of the first layer and the wiring of the third layer, a contact hole is formed so as not to contact the wiring of the second layer, and the wiring of the third layer is connected through this contact hole. Was connected to the wiring of the first layer. That is, as shown in the schematic sectional view of FIG. 7 and the wiring layout diagram of FIG. 8, the first wiring 72 is formed on the substrate 71. A first interlayer insulating film 73 is formed so as to cover the first wiring 72. Further, the first interlayer insulating film 7
The second wirings 74 and 75 are provided on the upper surface of the first wiring 72.
It is formed so as to traverse. In addition, each second wiring 7
A second interlayer insulating film 76 is formed so as to cover the layers 4, 75. The second wiring 7 is formed between the second interlayer insulating film 76 and the first interlayer insulating film 73 on the first-layer wiring 72.
The contact hole 77 is provided without coming into contact with 4, 75. Further, a third wiring 78 connected to the first wiring 72 via the contact hole 77 is formed on the upper surface of the second interlayer insulating film 76. The contact hole 77 is designed in consideration of the mask alignment margin 79 so as not to come into contact with the second wirings 74 and 75.

[0003]

However, in the above wiring structure, the mask alignment margin of the contact hole must be taken into consideration when designing the contact hole. Therefore, the interval between the second wirings must be wider than the total width of the contact hole width and the mask alignment margin. As a result, there is a limit in reducing the wiring density of the second wiring, which prevents high density mounting of the second wiring.

An object of the present invention is to provide a multi-layer wiring structure excellent in high-density mounting of wiring and a manufacturing method thereof.

[0005]

SUMMARY OF THE INVENTION The present invention is a multilayer wiring structure made to achieve the above object. That is,
A first wiring is formed on the substrate, and a first interlayer insulating film is formed so as to cover the first wiring. In addition, a plurality of second wirings having an insulating film formed on the upper surface are formed on the first interlayer insulating film, and the second interlayer insulating film covers the second wirings and the insulating films. Is deposited. Further, a contact hole is provided in the second interlayer insulating film between the second wirings at a predetermined position of the first wiring and the first interlayer insulating film, and an insulating sidewall is provided on a side wall of the contact hole. Are formed. A third wiring connected to the first wiring through the contact hole is formed on the second interlayer insulating film.
Alternatively, a conductive plug is provided inside the contact hole, and the third wiring is formed in a state of being connected to this plug.

In the above-mentioned method for manufacturing a multilayer wiring structure, in the first step, after forming the first wiring on the substrate, the first interlayer insulating film is formed so as to cover the first wiring. . Next, in a second step, after forming a plurality of second wirings each having an insulating film on the first interlayer insulating film, the second interlayer insulating film is formed so as to cover each second wiring and the insulating film. Form a film. Subsequently, in the third step, after providing a contact hole in the second interlayer insulating film between the second wirings at the predetermined position of the first wiring and the first interlayer insulating film, in the fourth step, A sidewall is formed on the sidewall of the contact hole. Then, in a fifth step, a third wiring is formed on the second interlayer insulating film in a state of being connected to the first wiring through the contact hole. Alternatively, after the fourth step is completed, a conductive plug is formed inside the contact hole in the fifth step, and then in the sixth step, in a state of being connected to the plug, on the second interlayer insulating film. A third wiring is formed on.

[0007]

In the multi-layer wiring structure having the above structure, the contact hole is formed in a self-aligned manner by forming the insulating sidewall on the side wall of the second wiring by utilizing the interval between the second wirings. . Therefore, the design size of the contact hole is reduced. Further, by forming the plug inside the contact hole, the connectivity between the first wiring and the third wiring is improved.

In the method of manufacturing the multilayer wiring structure, the width of the contact hole in the second inter-wiring direction is determined in a self-aligned manner by utilizing the space between the second wirings. Further, by forming an insulating side wall on the side wall of the contact hole, the insulating film between the contact hole and the second wiring is formed to the necessary minimum thickness. For this reason, the design size required to form the contact hole is minimized. In addition, by forming the plug in the contact hole, it is not necessary to consider the coverage when forming the third wiring.

[0009]

A first embodiment of the present invention will be described with reference to the schematic sectional view of FIG. 1 and the wiring layout diagram of FIG.
As shown in the figure, the first wiring 12 is formed on the substrate 11. A first interlayer insulating film 13 is formed so as to cover the first wiring 12. A plurality of second wirings 14 and 15 are formed on the first interlayer insulating film 13. Insulating films 16 and 17 are formed on the upper surfaces of the respective second wirings 14 and 15. Each second wiring 14,
A second interlayer insulating film 18 is formed so as to cover 15 and the insulating films 16 and 17. Further, contact holes 19 are provided in the second interlayer insulating film 18 and the first interlayer insulating film 13 between the second wirings 14 and 15 at predetermined positions of the first wiring 12. An insulating sidewall 20 is formed on the sidewall of the contact hole 19. Then, the first wiring 1 is formed through the contact hole 19.
A third wiring 21 connected to 2 is formed on the second interlayer insulating film 18. The multilayer wiring structure 1 is configured as described above.

In the multi-layer wiring structure 1 having the above structure, the distance between the second wirings 14 and 15 is set to the width of the contact hole 19, so that the contact hole 19 is set at the distance between the second wirings 14 and 15. The design dimension of width becomes smaller. Further, since the insulating sidewall 20 is formed on the side wall of the contact hole 19, the thickness of the second interlayer insulating film 18 between the contact hole 19 and the second wirings 14 and 15 is the minimum necessary thickness. Is enough.

Next, a method of manufacturing the multilayer wiring structure 1 of the first embodiment will be described with reference to manufacturing process diagrams (1) and (2) of FIGS. 3 and 4, a schematic cross-sectional view is shown on the left side of the drawings, and a wiring layout diagram is shown on the right side of the drawings. The first step shown in FIG. 3A is performed. In this step, after forming the first wiring 12 on the substrate 11 by a normal wiring forming technique, the first interlayer insulating film 13 is covered with the first wiring 12 by, for example, a chemical vapor deposition method.
To form a film.

Next, the second step shown in FIG. 3B is performed. In this step, for example, by chemical vapor deposition,
A film 31 forming a second wiring is formed on the upper surface of the first interlayer insulating film 13. Then, a silicon oxide film 32, for example, is formed on the upper surface of the film 31 forming the second wiring by, for example, a chemical vapor deposition method. Further, the etching mask forming film 33 is formed by, for example, the sputtering method. The etching mask forming film 33 is made of, for example, a tungsten (W) film. After that, by the usual photolithography technique and etching, the portion of the etching mask forming film 33 indicated by a broken line and the silicon oxide film 32
The portion indicated by the dotted chain line is removed, and etching masks 34 and 35 are formed with the remaining etching mask forming film 33,
Insulating films 16 and 17 are formed from the remaining silicon oxide film 32. Further, the portion indicated by the chain double-dashed line of the film 31 forming the second wiring is removed, and the remaining film 31 forming the second wiring forms second wirings 14 and 15.

Thereafter, as shown in FIG. 3C, the second wirings 14 and 15, the insulating films 16 and 17, and the etching masks 34 and 35 are first covered by, for example, a chemical vapor deposition method. The second interlayer insulating film 18 is formed.

Next, a third step shown in FIG. 4 (4) is performed. In this step, the second interlayer insulating film 18 and the first interlayer insulating film 13 between the second wirings 14 and 15 at predetermined positions of the first wiring 12 are contacted by a normal photolithography technique and etching. A hole 19 is provided. Further, the portions indicated by the chain double-dashed lines of the etching masks 34 and 35 are also removed by anisotropic etching, for example. At this time, the surface layer of the first wiring 12 may be slightly etched.

Subsequently, a fourth step shown in FIG. 4 (5) is performed. In this step, by the usual chemical vapor deposition method,
After forming the side wall forming film 36 on at least the side wall of the contact hole 19, the side wall shown by a chain double-dashed line other than the side wall forming film 36 formed on the side wall of the contact hole 19 by normal anisotropic etching. The formation film 36 is removed to form the sidewall 20.

Thereafter, a fifth step shown in FIG. 4 (6) is performed. In this step, for example, by chemical vapor deposition,
A film (37) for forming a third wiring is formed inside the contact hole 19 and on the upper surface of the second interlayer insulating film 18. Then, a film (37) for forming the third wiring by the usual photolithography technique and etching.
The unnecessary portion (not shown) is removed, and the third wiring 21 connected to the first wiring 12 is formed by the film (37) forming the third wiring.

In the method of manufacturing the multilayer wiring structure 1, the second method is used.
Since the space between the wirings 14 and 15 is used, the width of the contact hole 19 in the direction between the second wirings 14 and 15 is determined in a self-aligned manner. Further, by forming the insulating sidewall 20 on the side wall of the contact hole 19, the insulating film between the contact hole 19 and the second wirings 14 and 15 is formed by the sidewall 20 to a necessary minimum thickness. . Therefore, the design size required to form the contact hole 19 is minimized. Further the second wiring 1
Since the insulating films 16 and 17 are provided on the upper surfaces of the insulating films 16 and 17, and the etching masks 34 and 35 are formed on the upper surfaces of the insulating films 16 and 17, the contact holes 19 are formed in the second wirings 14 and 1.
Even if the insulating film 1 is formed so as to overlap with the insulating film 1
The second wirings 14 and 15 are not exposed by etching 6 and 17.

Next, the second embodiment will be described with reference to the schematic sectional view of FIG. The multilayer wiring structure 2 shown in the figure has a conductive plug 41 connected to the first wiring 12 inside the contact hole 19 of the multilayer wiring structure 1 described in FIG.
And the third wiring 21 is formed on the upper surface of the second interlayer insulating film 18 in a state of being connected to the plug 41. In FIG. 4, the same components as those described with reference to FIG. 1 are designated by the same reference numerals. The components other than the plug 41 are the same as those described with reference to FIG. 1 above, and thus the description thereof is omitted here.

In the multilayer wiring structure 2 having the above structure, the plug 41 is provided inside the contact hole 19,
The coverage of the third wiring 21 is improved. Therefore, the third wiring 21 does not become disconnected at the opening of the contact hole 19. Further, the plug 41 enhances the connectivity between the first wiring 12 and the third wiring 21.

Next, a method of manufacturing the multilayer wiring structure 2 of the second embodiment will be described with reference to the manufacturing process chart of FIG. From the first step to the fourth step, (1) to FIG.
Since (3) and (4) and (5) in FIG. 4 are the same as those described above, description thereof will be omitted here. Further, the same components as those described in FIGS. 3 and 4 are designated by the same reference numerals.

After that, a fifth step shown in FIG. 6A is performed. In this step, for example, by chemical vapor deposition,
A plug forming film 42 connected to the first wiring 12 is formed inside the contact hole 19 and on the upper surface of the second interlayer insulating film 18.
To form a film. The plug forming film 42 is made of, for example, a blanket tungsten film. Then, the portion indicated by the chain double-dashed line of the plug forming film 42 is removed by a normal etch back process, and the plug 41 is formed from the plug forming film 42 left inside the contact hole 19.

Then, a sixth step shown in FIG. 6B is performed. In this step, for example, by chemical vapor deposition,
A film (37) for forming a third wiring is formed on the upper surface of the plug 41 and the upper surface of the second interlayer insulating film 18. Then, by an ordinary photolithography technique and etching, an unnecessary portion (not shown) of the film (37) forming the third wiring is removed, and the remaining film (37) forming the third wiring is formed. Then, the third wiring 21 connected to the first plug 41 is formed.

In the method of manufacturing the multilayer wiring structure 2, the plug 41 is formed in the contact hole 19,
It is not necessary to consider the coverage in forming the third wiring 21 on the upper surface of the second interlayer insulating film 18.

[0024]

As described above, according to the multilayer wiring structure of the present invention, the width of the contact hole in the second inter-wiring direction is determined in a self-aligned manner by the distance between the second wirings. For this reason, the design size of the contact hole is reduced, so that the wiring formation area can be reduced. Therefore, high-density mounting of wiring is possible. In addition, since the plug is formed inside the contact hole, the first
It is possible to improve the connectivity between the second wiring and the third wiring.

In the manufacturing method of the present invention, the contact holes are formed between the second wirings in a self-aligned manner by utilizing the space between the second wirings, and further the insulating sidewalls are formed on the side walls of the contact holes. The insulating film between the contact hole and the second wiring can be formed to have the minimum necessary thickness. Therefore, the design size required to form the contact hole can be minimized. Further, by forming the plug in the contact hole, it is not necessary to consider the coverage when forming the third wiring, so that the formation of the third wiring is facilitated.

[Brief description of drawings]

FIG. 1 is a schematic configuration sectional view of a first embodiment.

FIG. 2 is a wiring layout diagram of the first embodiment.

FIG. 3 is a manufacturing process diagram (1) of the first embodiment.

FIG. 4 is a manufacturing process diagram (2) of the first embodiment.

FIG. 5 is a schematic configuration sectional view of a second embodiment.

FIG. 6 is a manufacturing process diagram of the second embodiment.

FIG. 7 is a schematic configuration sectional view of a conventional example.

FIG. 8 is a layout diagram of wiring in a conventional example.

[Explanation of symbols]

 1 Multilayer Wiring Structure 2 Multilayer Wiring Structure 11 Substrate 12 First Wiring 13 First Interlayer Insulating Film 14 Second Wiring 15 Second Wiring 16 Insulating Film 17 Insulating Film 18 Second Interlayer Insulating Film 19 Contact Hole 20 Side Wall 21 Third wiring 41 Plug

Claims (4)

[Claims] 1. A first wiring formed on a substrate, a first interlayer insulating film formed so as to cover the first wiring, and a plurality of first wirings formed on the first interlayer insulating film. Second wiring, an insulating film formed on each of the second wirings, a second interlayer insulating film formed to cover each of the second wirings and the insulating film, and the first wiring A contact hole formed in the second interlayer insulating film and the first interlayer insulating film between the second wirings at a predetermined position, and an insulating sidewall formed on a sidewall of the contact hole, A multi-layer wiring structure, which is connected to the first wiring through a contact hole, and comprises a third wiring formed on the second interlayer insulating film. 2. The method for manufacturing a multilayer wiring structure according to claim 1, wherein after forming the first wiring on the substrate, a first interlayer insulating film is formed so as to cover the first wiring. And a second step of forming a plurality of second wirings with an insulating film on the first interlayer insulating film, and then forming a second wiring in a state of covering the second wirings and the insulating film. A second step of forming an interlayer insulating film, and providing a contact hole in the second interlayer insulating film and the first interlayer insulating film between the second wirings at a predetermined position of the first wiring. A third step, a fourth step of forming an insulating sidewall on the side wall of the contact hole, and a state of being connected to the first wiring through the contact hole on the second interlayer insulating film. And a fifth step of forming a third wiring in the multilayer wiring structure. The method of production. 3. The multilayer wiring structure according to claim 1, wherein a conductive plug is provided inside the contact hole and the third wiring is connected to the plug. Construction. 4. The method of manufacturing a multilayer wiring structure according to claim 3, wherein after forming the first wiring on the substrate, a first interlayer insulating film is formed so as to cover the first wiring. And a second step of forming a plurality of second wirings with an insulating film on the first interlayer insulating film, and then forming a second wiring in a state of covering the second wirings and the insulating film. A second step of forming an interlayer insulating film, and providing a contact hole in the second interlayer insulating film and the first interlayer insulating film between the second wirings at a predetermined position of the first wiring. A third step, a fourth step of forming an insulating sidewall on the side wall of the contact hole, a fifth step of forming a conductive plug inside the contact hole, and a state of connecting to the plug. And a sixth step of forming a third wiring on the second interlayer insulating film. A method of manufacturing a multilayer wiring structure, comprising: