JPH05226475A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method of forming a contact hole stable and excellent in quality in a semiconductor device provided with laminated wiring layers. CONSTITUTION:When a first wiring layer 3 and a third wiring layer 7 separated from each other by a first interlayer insulating film 4 and a second interlayer insulating film 6 communicating with each other are directly connected together, a dummy contact hole 9 used only for connecting the wiring layers 3 and 7 together is provided to the first interlayer insulating film 4, and a second wiring layer and a dummy wiring layer 8 are formed at the same time. By this setup, overetching at the formation of contact holes caused by an aspect ratio difference between contact holes and the disconnection of a conductive layer inside a contact hole can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device having three or more wiring layers.

[0002]

2. Description of the Related Art In recent years, there has been no end to the trend toward higher integration and higher functionality of LSIs. To achieve this, finer patterns have been advanced, and the number of wiring layers that make up LSIs has also increased. Is following. A device having such a multilayer structure naturally has a large step difference on the surface, which causes various defects, and various improvements have been made in order to reduce such a step difference.

FIG. 4 is a sectional view showing the structure of a contact hole portion in a conventional semiconductor device. In the figure, 1 is a semiconductor substrate on which semiconductor elements are formed, 2 is a base insulating film made of a silicon oxide film formed on the semiconductor substrate 1,
3 is a first wiring layer made of an aluminum film which is a conductive layer formed on the base insulating film 2, 4 is a first interlayer insulating film made of a silicon oxide film formed on the first wiring layer 3, Reference numeral 5 denotes a second aluminum film formed on the first interlayer insulating film 4.
Wiring layer, 6 is a second interlayer insulating film made of a silicon oxide film formed on the second wiring layer 5, 7 is a third wiring layer made of an aluminum film, and 10 is on the second wiring layer 5. A contact hole for the third wiring layer 7 provided in the second interlayer insulating film 6, and 11 provided over the first and second interlayer insulating films 4 and 6 on the first wiring layer 3. This is a contact hole for the formed third wiring layer 7.

Next, a method of manufacturing a contact hole portion of a semiconductor device configured as described above will be described with reference to FIGS.
Will be sequentially described. First, a predetermined process is performed to form a semiconductor element on the semiconductor substrate 1 (not shown). afterwards,
A silicon oxide film is formed on the semiconductor substrate 1 by the CVD method or the like to form the base insulating film 2. An aluminum film is formed on the underlying insulating film 2 by the sputtering method or the like, and the first wiring layer 3 is formed by the photolithography and the etching method or the like. The first wiring layer 3 and the semiconductor element are connected to each other via a contact hole (not shown) provided in the base insulating film 2 (FIG. 5A). Next, a silicon oxide film is formed on the entire surface by a CVD method or the like to form the first interlayer insulating film 4 (FIG. 5).
(B)). Next, an aluminum film is formed by the sputtering method or the like, and the second wiring layer 5 is formed by the photolithography and the etching method or the like. The second wiring layer 5 and the first wiring layer 3
Are connected to each other via a contact hole (not shown) provided in the first interlayer insulating film 4. (FIG.5 (c)). Next, a silicon oxide film is formed on the entire surface by a CVD method or the like,
The second interlayer insulating film 6 is used (FIG. 5D). Then the second
Of the contact hole 10 in the second interlayer insulating film 6 on the wiring layer 5 of
And the first interlayer insulating film 4 on the first wiring layer 3 and the second
A contact hole 11 is formed at the same time across the interlayer insulating film 6 by the photolithography and the etching method (FIG. 5).
(E)). After that, as shown in FIG. 4, an aluminum film is formed on the entire surface by the sputtering method or the like, and the third wiring layer 7 is formed by the photolithography and the etching method or the like.

[0005]

Since the conventional semiconductor device is constructed as described above, the third semiconductor device shown in FIG.
When the contact holes 10 and 11 are provided in the interlayer insulating films 4 and 6 to electrically connect the wiring layer 7 of the first wiring layer 7 to the first wiring layer 3 and the second wiring layer 5, Since the interlayer insulating film of 2 is composed of two layers of the first interlayer insulating film 4 and the second interlayer insulating film 6, and the interlayer insulating film on the second wiring layer 5 is composed of the second interlayer insulating film 6, The interlayer insulating film thickness on the first wiring layer 3 is thicker than the interlayer insulating film thickness on the second wiring layer 5. Therefore, comparing the aspect ratio (ratio of the depth to the opening width of the contact hole) of the contact hole 11 on the first wiring layer 3 and the contact hole 10 on the second wiring layer 5, the first wiring layer 3 The upper contact hole 11 becomes larger. For these reasons, disconnection is likely to occur in the contact hole 11 when the third wiring layer 7 is formed. Also,
Since the two contact holes 10 and 11 are formed through the same process, the contact hole 10 on the second wiring layer 5 is over-etched when the contact hole 11 is formed, and a semiconductor device having excellent characteristics can be obtained. There was a problem that it could not be done.

The present invention has been made to solve the above problems, and provides a method of manufacturing a semiconductor device having three or more laminated wiring layers capable of obtaining good and stable electrical connection. The purpose is to do.

[0007]

In the method of manufacturing a semiconductor device according to the present invention, when a plurality of insulating films that are connected to each other are used to directly connect conductive layers that are separated from each other by a contact, each insulating film of the plurality of insulating films is connected. A contact hole is formed for each layer of the film, and a dummy contact for only the direct connection is formed at the same time as each conductive layer in contact with the upper part of each insulating film.
These dummy contacts are sequentially connected to electrically connect the separated conductive layers.

[0008]

According to the method of manufacturing the semiconductor device of the present invention,
When the conductive layers that are separated from each other by interposing a plurality of insulating films that are connected to each other are directly connected by a contact, a contact hole is formed in each insulating film of each of the plurality of insulating films to contact each upper part of the insulating films. At the same time as forming the dummy contacts for the direct connection at the same time as the conductive layer and connecting the dummy contacts in order to electrically connect the isolated conductive layers, the contact holes formed at the same time always have the aspect ratio of Equal to the source. Therefore, it is possible to prevent over-etching caused by simultaneously forming contact holes having different aspect ratios, and disconnection of contacts in the contact holes.

[0009]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the description of the part overlapping the description of the conventional technique will be appropriately omitted.

FIG. 1 is a sectional view showing the structure of a contact hole portion of a semiconductor device according to an embodiment of the present invention. In the figure, 1 to 7 are equivalent to those in the conventional example. Reference numeral 8 is a dummy wiring layer formed on the first wiring layer 3 and formed at the same time as the second wiring layer, which is made of an aluminum film, and connects the first wiring layer 3 and the third wiring layer 7. It is a relay wiring layer used only for.

FIG. 2 is a sectional view showing a manufacturing process of the semiconductor device of FIG. The steps shown in FIGS. 2A and 2B are the same as the steps shown in FIGS. 5A and 5B of the conventional example, and detailed description thereof will be omitted.

Next, at least two contact holes 9 are formed in the region of the first interlayer insulating film 4 which is on the first wiring layer 3.
Are formed close to each other. This contact hole 9
Is for the dummy wiring layer 8 used only for connecting the first wiring layer 3 and the third wiring layer 7 (FIG. 1).
(C)). Next, an aluminum film is formed by the sputtering method or the like, and the second wiring layer 5 and the dummy wiring layer 8 are formed by the photolithography and the etching method. The second wiring layer 5 and the first wiring layer 3 are connected to each other via a contact hole (not shown) provided in the first interlayer insulating film 4 (FIG. 2 (d)). Next, a silicon oxide film is formed on the entire surface by the CVD method or the like to form the second interlayer insulating film 6 (FIG. 2).
(E)). Next, contact holes 10 and 12 are formed in the second interlayer insulating film 6 on the second wiring layer 5 and the dummy wiring layer 8 (FIG. 2 (f)). Thereafter, as shown in FIG. 1, an aluminum film is formed by the sputtering method or the like, and the third wiring layer 7 is formed by the photolithography and the etching method or the like.

At this time, the contact hole 1 according to the present invention
The aspect ratio of 2 is the conventional contact hole 1 shown in FIG.
Since it is smaller than 1 and is equal to the aspect ratio of the contact hole 10 formed at the same time, disconnection in the contact hole can be prevented and the contact hole 10 formed at the same time.
Since over-etching can be prevented, a good contact hole can be formed, and a semiconductor device manufacturing method with excellent characteristics can be obtained.

Embodiment 2 In Embodiment 1 described above, the case where at least two contact holes 9 for the dummy wiring layer 8 are formed is shown. However, as shown in FIG. 3, even if there is one contact hole 9, the dummy wiring layer 8 is formed. Can be formed, and the same effect as that of the first embodiment can be obtained.

Third Embodiment In the first embodiment, the case where at least two contact holes 9 for the dummy wiring layer 8 are formed is shown. However, even if the contact holes 9 have a donut shape, Has the same effect as.

Embodiment 4 In the above Embodiments 1, 2, and 3, the case where an aluminum film is used as the wiring layer is shown, but an aluminum alloy may be used. Although the case where the silicon oxide film is used as the interlayer insulating film is shown, other insulating films such as a silicon nitride film may be used. In any of the above cases, the same effect as that of the above embodiment can be obtained.

Fifth Embodiment In the first embodiment described above, the case where the contact is provided over the two layers of the interlayer insulating film has been described. However, when the number of contacts is three or more, the dummy wiring layers are sequentially stacked and connected in the same manner as described above. The same effect as in Example 1 is obtained.

Further, the present invention can be applied by including the semiconductor element formed on the semiconductor substrate 1 and the base insulating film formed thereon as the target of the conductive layer and the insulating film respectively in the claims. ..

[0019]

As described above, according to the present invention, when a plurality of insulating films connected to each other are used to directly connect conductive layers separated from each other by a contact, a contact hole is provided for each insulating film of the plurality of insulating films. And forming dummy contacts only for the direct connection at the same time as forming the conductive layers in contact with the upper portions of the insulating films, and sequentially connecting the dummy contacts to electrically connect the isolated conductive layers. Therefore, it is possible to prevent overetching at the time of contact hole formation and disconnection of the conductive layer in the contact hole due to the difference in aspect ratio between the contact holes, and to provide a method for manufacturing a semiconductor device having good and stable electrical characteristics. It has the effect of being obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a contact hole portion of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the manufacturing process of the semiconductor device of the invention shown in FIG.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a sectional view showing a structure of a contact hole portion of a conventional semiconductor device.

FIG. 5 is a cross-sectional view showing a manufacturing process of the conventional semiconductor device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Base insulating film 3 First wiring layer 4 First interlayer insulating film 5 Second wiring layer 6 Second interlayer insulating film 7 Third wiring layer 8 Dummy wiring layer 9 Dummy wiring layer contact hole

Claims (1)

[Claims] 1. A plurality of insulating films and conductive layers are alternately formed on a semiconductor substrate in a predetermined pattern, and contact holes are formed in the insulating film to simultaneously form the conductive layer in contact with the upper portion of the insulating film. In a method of manufacturing a semiconductor device, wherein a contact for electrically connecting to a conductive layer in contact with a lower portion of the insulating film is formed in the contact hole, a conductive layer separated from each other with a plurality of insulating films connected to each other is interposed. When the above-mentioned contacts are directly connected to each other, a contact hole is formed for each insulating film of the plurality of insulating films, and a dummy contact only for the direct connection is formed at the same time as each conductive layer contacting the upper part of each insulating film. A method of manufacturing a semiconductor device, wherein the dummy contacts are formed and are sequentially connected to electrically connect the separated conductive layers.