JPH09293778A - Method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high integration by forming a connecting metal by self alignment on a first metallic wiring for the connection of the first and second metallic wirings. SOLUTION: The first aluminum film 7 is formed on the whole surface of an insulating film 2 formed on a semiconductor substrate 1 and then a barrier metal film 8 and the second aluminum film 9 are continuously formed on the film 2. Next, the films 9, 8 and 7 are etched away to expose the insulating film 2. Next, the film 9 is etched a way using e.g. photoresist as a mask excluding a part of the film 9. Successively, when the exposed film 8 is selectively etched away to expose the first aluminum wiring 3, a connecting metal 10 in a protruding structure on the wiring 3 is formed by self alignment with the wiring 3. Later, after coating the whole surface with an interlayer insulating film 4, a structure filled up with the connecting metal is formed in the interlayer insulating film 4. Finally, the third aluminum film 12 to be the second aluminum wiring is formed on the whole surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a multi-layer wiring in a semiconductor device having a multi-layer wiring structure, and in particular, a connecting metal for connecting an upper wiring and a lower wiring is self-aligned with a lower wiring and an interlayer insulating film. Manufacturing method for forming the same.

[0002]

2. Description of the Related Art In recent years, in a semiconductor device, particularly in an LSI, an aluminum multi-layer wiring structure has been used due to its high integration. After forming an interlayer insulating film such as a plasma CVD oxide film on the first aluminum wiring, a connection hole is formed by selective etching to expose a part of the first aluminum wiring, and the second aluminum wiring is formed thereon. Are laminated to form a multilayer wiring structure.

Specifically, FIG. 9 shows a plan view of a conventional multilayer wiring structure, and FIG. 10 shows a sectional view thereof. In the figure, 1 is a semiconductor substrate, 2 is an insulating film made of an oxide film or the like formed on the semiconductor substrate 1, 3 is a first aluminum wiring, 4 is an interlayer insulating film made of a plasma CVD oxide film, and 5 is a first insulating film. 2 is an aluminum wiring, 6 is for connecting the first aluminum wiring 3 and the second aluminum wiring 5,
It is a connection hole formed inside.

In the method of forming such a multilayer wiring structure, first, the first aluminum wiring 3 is formed on the insulating film 2, the interlayer insulating film 4 is formed on the entire surface, and then the first aluminum wiring 3 is formed. A part of the interlayer insulating film 4 is etched to form the connection hole 6. An aluminum film to be the second aluminum wiring is formed on the entire surface and patterned to form the second aluminum wiring 5. By forming in this way, the first aluminum wiring 3 and the second aluminum wiring 3
The aluminum wiring 5 is connected through the connection hole 6.

[0005]

When a part of the interlayer insulating film 4 is etched in the first aluminum wiring 3 to form the connection hole 6, the photoresist serving as an etching mask is displaced. Considering the case, the margin d corresponding to the alignment accuracy is required. Therefore, there is a problem that high integration cannot be achieved.

FIG. 11 shows another multilayer wiring structure.
When the opening size of the connection hole 6 formed in the interlayer insulating film 4 is reduced to achieve high integration, the second aluminum wiring 5 formed by the vapor deposition method or the sputtering method is less likely to enter the connection hole 6. However, there is a problem that reliability is deteriorated, such as an increase in resistance. Therefore, the connection hole 6
It is necessary to increase the size of the opening to a certain extent, which also causes a problem that high integration cannot be achieved.

It is an object of the present invention to solve the above problems and to provide a manufacturing method capable of forming a highly reliable multilayer wiring structure which can be highly integrated.

[0008]

In order to achieve the above object, the first invention of the present application is, in a method of manufacturing a semiconductor device having a multilayer wiring structure, a step of forming a first wiring metal film, and A step of forming another metal film on the wiring metal film, the step of etching the other metal film and the first wiring metal film to form a first wiring pattern, and the etching first Part of the other metal film on the wiring metal film is removed by etching to form a connection metal made of the another metal film protruding above the first wiring made of the first wiring metal film. A step of exposing the connection metal to form an insulating film covering the first wiring, a step of forming a second wiring metal film on the exposed connection metal and insulating film, The wiring metal film of is etched to form a second wiring pattern, It is characterized in that a step of forming a second wiring that is in contact with the serial connection metal.

A second invention of the present application is a method of manufacturing a semiconductor device having a multi-layer wiring structure, wherein a step of forming a first wiring metal film and a step of etching the first wiring metal film are performed. A step of forming a wiring pattern; a step of etching away a part of the first wiring metal film to form a connection metal protruding on the first wiring; and a step of exposing the connection metal to form the connection metal. A step of forming an insulating film covering the wiring; a step of forming a second wiring metal film on the exposed connection metal and insulating film; and a step of etching the second wiring metal film to form a second wiring And a step of forming a pattern and forming a second wiring in contact with the connection metal.

According to the first and second inventions of the present application, the connecting metal protruding above the first wiring can be formed in a self-aligned manner with respect to the first wiring. Further, since the interlayer insulating film is formed after the connection metal is formed, the interlayer insulating film can be formed in a self-aligned manner. Further, even if the size of the connecting metal is reduced, it is possible to reliably form the shape in which the connecting metal is filled in the opening of the interlayer insulating film. With such a configuration, high integration is achieved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described. A first aluminum film 7 to be a first aluminum wiring is formed on the entire surface of an insulating film 2 made of an oxide film or the like formed on a semiconductor substrate 1, and a barrier made of titanium tungsten, tungsten nitride or the like is formed thereon. The metal film 8 and the second aluminum film 9 serving as a connecting metal are continuously formed (FIG. 1). Here, as the barrier metal film 8, it is preferable to select a metal film or the like that can be selectively etched with the first and second aluminum films 7 and 9 and can be connected with low resistance.

After that, for example, using a photoresist as a mask to form the first aluminum wiring pattern,
The second aluminum film 9, the barrier metal film 8 and the first aluminum film 7 are removed by etching to expose the insulating film 2 (FIG. 2).

Next, in order to form a connection metal for connecting to the second aluminum wiring, a part of the second aluminum film 9 formed on the first aluminum wiring 3 formed previously (the first aluminum wiring 9 formed later). Except for the second wiring (the connection with the upper wiring), the photoresist is used as a mask and removed by etching. Here, the second aluminum film 9 is etched by selectively etching the second aluminum film 9 without etching the first aluminum wiring 3 by selecting a condition to stop at the barrier metal film 8. be able to. Further, as the photoresist used as the mask, a pattern having a large opening in the lateral direction of the first aluminum wiring 3 may be used, and it is not necessary to provide a margin for alignment.

After that, the exposed barrier metal 8 is selectively etched to expose the first aluminum wiring 3.
By forming in this way, the first aluminum wiring 3
The connection metal 10 having a protruding structure can be formed thereon in a self-aligned manner with respect to the first aluminum wiring 3. FIG. 3 shows a first part in a direction orthogonal to the sectional view shown in FIG.
3 is a sectional view of the aluminum wiring 3 portion of FIG. (Hereinafter, FIGS. 4 to 7 are sectional views taken in a direction orthogonal to FIG. 3.)

Then, according to a general method for manufacturing a semiconductor device, the entire surface is covered with an interlayer insulating film 4 thicker than the connecting metal 10 (FIG. 4), and a thick photoresist 11 is formed on the entire surface to flatten the surface (FIG. 5), anisotropic etching is performed under the condition that the etching rates of the photoresist 11 and the interlayer insulating film 4 are equal. The etching is stopped when the connecting metal 10 is exposed. As a result, the connection metal 1 is formed in the interlayer insulating film 4.
Structures filled with 0 can be formed (FIG. 6). The portion excluding the connection metal 10 is covered with the interlayer insulating film 4, and the first aluminum wiring 3 is also covered with the interlayer insulating film 4.

Next, a third aluminum wiring which becomes a second aluminum wiring is formed.
The aluminum film 12 is formed on the entire surface (FIG. 7), a photoresist of the second aluminum wiring pattern is formed, and etching is performed to form the second aluminum wiring.

By forming as described above, the first aluminum wiring and the second aluminum wiring are connected to the connecting metal 1.
The connection metal and the first aluminum wiring are formed in a self-aligned manner. Therefore, it is not necessary to provide a margin for alignment, and high integration can be achieved. Further, since the interlayer insulating film is formed after the connection metal is formed, the interlayer insulating film and the connection metal can be formed in a self-aligned manner, and thus high integration can be achieved. Further, the connection metal formed in the interlayer insulating film is completely filled in the connection hole, and even when the size of the connection hole, that is, the size of the connection metal is reduced, the first aluminum wiring and the second aluminum wiring are formed. It is possible to provide a highly reliable and highly integrated wiring structure that can be reliably connected to the wiring.

Next, a second embodiment of the present invention will be described. Similar to the first embodiment, a first aluminum wiring and a first aluminum film serving as a connection metal are formed on the entire surface of an insulating film made of an oxide film or the like formed on a semiconductor substrate. Here, the difference from the first embodiment is that the film thickness of the first aluminum film is the same as that of the first embodiment.
That is, the aluminum wiring, the barrier metal film, and the connection metal are formed to have a combined thickness. Then, using, for example, a photoresist as a mask, the first wiring pattern is etched to expose the insulating film on the semiconductor substrate. Then pattern the photoresist, for example,
The first aluminum film is partially etched so that the connection metal portion protruding above the first aluminum wiring is formed. FIG. 8 shows a sectional view of a process corresponding to FIG. 3 of the first embodiment.

As shown in FIG. 8, the first aluminum wiring 3 and the connecting metal 10 protruding above the first aluminum wiring 3 are formed only by the first aluminum film. Therefore, compared with the first embodiment, the steps for forming the barrier metal film and the second aluminum film can be omitted, and a similar structure can be formed by a simpler process. it can.

After that, as in the first embodiment, an interlayer insulating film 4 is formed on the entire surface, a thick photoresist 11 is formed on the interlayer insulating film 4, and after planarization, the photoresist 11 and the interlayer insulating film 4 have the same etching rate. By etching under the conditions to expose the connection metal 10, a structure in which the connection metal 10 is filled in the interlayer insulating film 4 can be formed.

Next, a third aluminum wiring is formed.
The second aluminum wiring 5 is formed by forming the aluminum film 12 on the entire surface, forming a photoresist having a pattern of the second aluminum wiring, and etching the photoresist.

As described above, according to the present invention, the connection metal 10 connecting the first aluminum wiring and the second aluminum wiring can be formed in a self-aligned manner with respect to the first aluminum wiring 5. Therefore, high integration can be achieved. In addition, after forming the connection metal 10, the interlayer insulating film 4 is formed.
Therefore, the first aluminum wiring 3 and the second aluminum wiring 5 can be reliably connected, and a highly reliable wiring structure can be provided. Furthermore, the step of exposing the connection metal from the interlayer insulating film can also be performed in a self-aligning manner, which also proves to be advantageous for high integration.

In the second embodiment, it is not necessary to form the barrier metal film 8 or to form another aluminum film 9 on the barrier metal film, as compared with the first embodiment.
The multilayer wiring structure can be formed by a simpler process.

Although the embodiment of the present invention has been described above by taking aluminum as an example of the wiring metal and the connecting metal, the present invention is not limited to aluminum as the wiring metal and other metals. , For example, aluminum and polysilicon, polysilicon and polysilicon, aluminum and gold, and the like. In addition, copper, tungsten, platinum,
It is also possible to apply to a multilayer wiring structure made of a metal such as molybdenum.

[0025]

As described above, according to the present invention, since the first metal wiring and the second metal wiring are connected, the connection metal can be formed on the first metal wiring in a self-aligning manner. Therefore, high integration could be realized. Further, since the interlayer insulating film is formed after the connection metal is formed, the connection metal is sufficiently filled in the connection hole, and the first wiring metal and the second wiring metal can be surely connected to each other. The size of the connecting metal can be reduced, which is advantageous for high integration.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating an embodiment of the present invention.

FIG. 3 is a sectional view illustrating an embodiment of the present invention.

FIG. 4 is a sectional view illustrating an embodiment of the present invention.

FIG. 5 is a sectional view illustrating an embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating an embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating an embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating another embodiment of the present invention.

FIG. 9 is a plan view illustrating a conventional multilayer wiring structure.

FIG. 10 is a cross-sectional view illustrating a conventional multilayer wiring structure.

FIG. 11 is a sectional view illustrating a conventional multilayer wiring structure.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Insulating Film 3 First Aluminum Wiring 4 Interlayer Insulating Film 5 Second Aluminum Wiring 6 Connection Hole 7 First Aluminum Film 8 Barrier Metal Film 9 Second Aluminum Film 10 Connection Metal 11 Photoresist 12 Third Aluminum film

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device having a multilayer wiring structure, the step of forming a first wiring metal film; the step of forming another metal film on the first wiring metal film; Etching the metal film and the first wiring metal film to form a first wiring pattern, and etching away a part of the another metal film on the etched first wiring metal film. A step of forming a connection metal made of the other metal film protruding above the first wiring made of the first wiring metal film, and an insulating film exposing the connection metal and covering the first wiring And a step of forming a second wiring metal film on the exposed connection metal and insulating film, and etching the second wiring metal film to form a second wiring pattern, Forming a second wiring in contact with the connecting metal. The method of manufacturing a semiconductor device, characterized in that. 2. A method of manufacturing a semiconductor device having a multi-layered wiring structure, the step of forming a first wiring metal film, and the step of etching the first wiring metal film to form a first wiring pattern. A step of etching away a part of the first wiring metal film to form a connecting metal projecting on the first wiring, and an insulating film exposing the connecting metal and covering the first wiring. A step of forming, a step of forming a second wiring metal film on the exposed connection metal and insulating film, and a step of etching the second wiring metal film to form a second wiring pattern. And a step of forming a second wiring in contact with the metal.