JP2819929B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to an improved method of forming a metal wiring and a process of forming the metal wiring.

[0002]

2. Description of the Related Art In recent years, in a semiconductor device having a metal wiring and a contact hole, as the degree of integration of the semiconductor device increases, the line width of the metal wiring becomes narrower and the aspect ratio of the contact hole becomes larger. For this reason, the current density flowing in the wiring increases, and the coverage of the metal wiring in the contact hole deteriorates, so that the reliability of the wiring and the contact cannot be guaranteed. As a wiring material for a conventional semiconductor device which solves this problem, a wiring material having a two-layer structure of an aluminum alloy film and a barrier metal film is known. Usually, a barrier metal film is deposited by a sputtering method, and then an aluminum alloy film is deposited. As the barrier metal film, a high melting point metal compound film such as a high melting point metal film or a high melting point metal nitride film is used.

However, when the integration degree is further increased and the contact hole size is reduced, if the barrier metal film is formed by the sputtering method, the coverage is poor and the thickness of the barrier metal film at the bottom of the contact hole becomes extremely large. There has been a problem that the thickness of the contact becomes thin and the reliability of the contact cannot be guaranteed. As a semiconductor device that solves this problem, a method has been proposed in which a tungsten film formed by a chemical vapor deposition method is used as a barrier metal film instead of a barrier metal film formed by a sputtering method. In the chemical vapor deposition method, the coverage is greatly improved as compared with the sputtering method. Therefore, a tungsten film is formed also at the bottom of the contact, and the problem of contact reliability is solved.

As an improvement of this method, a contact hole is buried with tungsten by depositing a tungsten film with a thickness of at least half of the short side of the contact hole, and then an aluminum alloy film is deposited. so,
A structure for solving the problem of insufficient coverage of the aluminum alloy film has also been proposed. However, at this time, the film thickness of the wiring becomes large. For this reason, there has been proposed a method in which a tungsten film is deposited to a thickness equal to or more than half of the short side of the contact hole and then used as a wiring without depositing an aluminum alloy. However, in this case, since the aluminum alloy is not used, the wiring resistance increases. For this reason, after depositing a tungsten film to a thickness of at least half of the short side of the contact hole, the entire thickness of the tungsten film is etched to reduce the thickness of the tungsten film, and then an aluminum alloy film is deposited. Accordingly, a structure in which the total film thickness of the wiring is reduced has been reported. Such a method is described, for example, in I Triple EDM Technical Digest, IEEE / IEDM / Technic.
al. Digest p 462-465, 1988.

Referring to the drawings, an example of the above-described conventional semiconductor device in which a tungsten film is deposited to a thickness equal to or more than half the short side of a contact hole and then an aluminum alloy film is deposited will be described.

FIG. 3 is a cross-sectional view of a main part of a conventional semiconductor device. In FIG. 3, 1 is a silicon substrate, 2 is a first insulating film, 3 is a metal wiring, 4 is a second insulating film, and 5 is a contact hole. Reference numeral 6 denotes a titanium tungsten (TiW) film serving as a seed layer, which is formed to serve as a growth nucleus for the tungsten film to grow also on the insulating film. Since a tungsten film formed by a chemical vapor deposition method does not grow on an insulating film, when a tungsten film is formed on the insulating film, it is necessary to form a seed layer on the insulating film. Reference numeral 7 denotes a tungsten film formed by a chemical vapor deposition method, and 9 denotes an aluminum alloy film.

In the semiconductor device configured as described above, by forming the tungsten film 7 by using the chemical vapor deposition method, the contact hole is filled with tungsten, and the reliability of the contact hole is guaranteed. In addition, by forming a multilayer structure of the tungsten film 7 and the aluminum alloy film 8, it becomes possible to lower the specific resistance as compared with the structure of only the tungsten film. In addition, irregularities on the surface of the tungsten film deposited by the chemical vapor deposition method generally become large as shown in FIG.

In addition, the reliability as a wiring having a multilayer structure of a barrier metal film and an aluminum alloy film is considered as a barrier metal film.
Hoang et al. (HH Hoan) reported a comparison between a case using a tungsten film deposited by chemical vapor deposition and a case using a TiW film deposited by sputtering.
get. al. ), Proceeding I Triple EV MIC Conference, P
raceding / IEEE / Conference
pp. 133-141, 1990. According to this report, the tungsten film deposited by the chemical vapor deposition method has large surface irregularities. Therefore, when the tungsten film is used as the barrier metal film, the crystal grain of the aluminum alloy film is larger than when the TiW film is used. It is described that the size is reduced and the reliability (electromigration resistance) as a wiring is poor. Further, it is described that by setting the concentration of copper in the aluminum alloy film to 2%, there is no difference in reliability between the two types of barrier metal films.

It is known that the electromigration resistance increases as the crystal grain size of the aluminum alloy film increases. Electromigration is a phenomenon in which when electrons flow, the electrons collide with aluminum atoms and move the aluminum atoms. Since the aluminum atoms move along the crystal grain boundaries, the A direction in FIG.
In a portion where a plurality of crystal grain boundaries gather at one crystal grain boundary as shown in (1), hillocks are generated due to an excessive amount of aluminum atoms, which causes a short circuit. It is known that voids are generated due to a shortage of aluminum atoms in a portion separated into grain boundaries, which causes disconnection. For this reason, if the crystal grains are enlarged, the crystal grain boundaries are reduced, and the electromigration resistance is improved.

It is known that when copper is added as an impurity to an aluminum alloy, electromigration resistance is improved, and the effect is higher as the concentration of copper is higher. This is thought to be due to the fact that copper precipitates at the crystal grain boundaries and suppresses the movement of aluminum atoms at the crystal grain boundaries.

[0011]

However, when copper is used,
In the above-described configuration using an aluminum alloy film containing%, there remains a problem in corrosion of wiring. It is also known that the higher the copper concentration, the more easily the aluminum alloy is likely to corrode. For this reason, copper is usually contained in an amount of usually 0.5%, at most about 1%. As the miniaturization of semiconductor devices progresses, wiring widths become narrower, and even smaller corrosion causes defects, so that it is becoming increasingly difficult to include a large amount of copper.

In view of the above problems, the present invention provides a semiconductor device having high reliability as a wiring (electromigration resistance) and using no corrosion while using an aluminum alloy film and a tungsten film formed by a chemical vapor deposition method, and its manufacture. It provides a method.

[0013]

According to a first aspect of the present invention, there is provided a semiconductor device having a metal wiring and a contact hole connected to the metal wiring. An insulating film, a contact hole for connecting to the metal wiring selectively opened in the insulating film, a seed layer on the entire surface of the insulating film and the contact hole, and a chemical vapor deposition method on the seed layer. A refractory metal film formed, a refractory metal film or a refractory metal compound film formed as a buffer layer on the refractory metal film formed by the chemical vapor deposition method, and an aluminum alloy on the buffer layer And a membrane.

According to a second aspect of the present invention, in the semiconductor device having a diffusion layer and a contact hole connected to the diffusion layer, an insulating film on the diffusion layer and the diffusion film selectively opened in the insulating film. A contact hole for connecting to a layer, a seed layer on the entire surface of the insulating film and the contact hole, a high melting point metal film formed on the seed layer by a chemical vapor deposition method, It comprises a high melting point metal film or a high melting point metal compound film formed as a buffer layer on the formed high melting point metal film, and an aluminum alloy film on the buffer layer.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device having a metal wiring and a contact hole for connecting to the metal wiring. Forming a film, selectively opening a contact hole for connecting to the metal wiring in the insulating film, forming a seed layer over the entire surface of the insulating film and the contact hole, Forming a high melting point metal film on the layer by chemical vapor deposition, and forming a high melting point metal film or a high melting point metal compound film as a buffer layer on the high melting point metal film formed by chemical vapor deposition. And a step of forming an aluminum alloy film on the buffer layer.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a semiconductor device having a diffusion layer and a contact hole for connecting to the diffusion layer, wherein an insulating film is formed on the diffusion layer. A step of selectively opening a contact hole for connecting to the diffusion layer in the insulating film; a step of forming a seed layer on the entire surface of the insulating film and the contact hole; and a step of chemical vapor deposition on the seed layer Forming a high melting point metal film by a method,
A step of forming a high melting point metal film or a high melting point metal compound film as a buffer layer on the high melting point metal film formed by the chemical vapor deposition method, and a step of forming an aluminum alloy film on the buffer layer. Things.

The buffer layer according to claim 1 or 2 is a titanium nitride (TiN) film or a titanium tungsten (TiW) film.

After the step of forming the refractory metal film by the chemical vapor deposition method according to claim 3 or 4, the substrate is washed with sulfuric acid or fuming nitric acid to form a buffer layer on the refractory metal film surface as a buffer layer. Forming an oxide film;

After the step of forming the refractory metal film by chemical vapor deposition according to claim 3 or 4, a heat treatment is performed to form a refractory metal oxide film as a buffer layer on the surface of the refractory metal film. Process.

After the step of forming the refractory metal film by the chemical vapor deposition method according to claim 3 or 4, a heat treatment is performed in an ammonia atmosphere or a plasma treatment is performed in a nitrogen atmosphere to obtain the refractory metal film. Forming a refractory metal nitride film as a buffer layer on the surface;

[0021]

According to the structure of the present invention, since the high melting point metal film formed by the chemical vapor deposition method has good coverage, the reliability of the contact is guaranteed, and the wiring is formed by forming a multilayer film of the high melting point metal film and the aluminum alloy. The resistance can be reduced, and a buffer layer is formed between the refractory metal film and the aluminum alloy film.This buffer layer prevents diffusion of impurities from the refractory metal film formed by chemical vapor deposition. Even if the surface of the refractory metal film has large irregularities, the crystal grain of the aluminum alloy does not become small, the electromigration resistance as wiring is improved, and the concentration of copper contained in the aluminum alloy film can be reduced. Therefore, no corrosion occurs in the aluminum alloy film.

[0022]

(Embodiment 1) A semiconductor device as one embodiment of the present invention and a method of manufacturing the same will be described below with reference to the drawings. FIG. 1 is a sectional view showing a main part of a semiconductor device according to a first embodiment of the present invention.

In FIG. 1, 1 is a silicon substrate, 2 is a first insulating film, 3 is a first metal wiring, 4 is a second insulating film having a thickness of, for example, 1.5 μm, and 5 is a second insulating film. The contact hole opened in the film 4 has, for example, a short side length of 4
00 nm. 6 is a seed layer, for example, a TiW film 5
The thickness is 0 nm, and 7 is a tungsten film formed by a chemical vapor deposition method, and has a thickness of, for example, 300 nm. The seed layer 6 is used as a growth nucleus when the tungsten film 5 is formed. Since a tungsten film formed by a chemical vapor deposition method does not grow on an insulating film, when a tungsten film is formed on the insulating film, it is necessary to form a seed layer on the insulating film. Reference numeral 8 denotes a buffer layer, for example, a TiN film having a thickness of 50 nm, and reference numeral 9 denotes an aluminum alloy film deposited by sputtering, for example, having a thickness of 300 nm.

Next, a method of manufacturing a semiconductor device according to the first embodiment of the present invention will be described with reference to FIG. For example, a silicon oxide film is formed as a first insulating film 2 on a silicon substrate 1, and then, for example, a tungsten silicide film is formed as a desired metal wiring 3 on the first insulating film 2, and then a second insulating film 4 is formed. For example, a silicon oxide film is used as 1.
It is deposited on the entire surface with a thickness of 5 μm. Then, the second insulating film 4
Contact hole 5, for example, the length of the short side is 400
An opening with a size of nm. Next, for example, a TiW film is deposited as a seed layer 6 to a thickness of 50 nm, and then a tungsten film 7 is deposited to a thickness of, for example, 300 nm by the chemical vapor deposition method shown in Chemical Formula 1. The seed layer 6 is used as a growth nucleus when the tungsten film 7 is formed. Here, after the tungsten film 7 is formed, the thickness of the tungsten film 7 may be reduced by etching the entire surface.

[0025]

Embedded image 2WF ₆ + 6H ₂ → 2W + 12HF

After that, for example, a titanium nitride (TiN) film is deposited as a buffer layer 8 by using a 50-nm-thick sputtering method, and then an aluminum alloy film 9 is deposited, for example, to a thickness of 300 nm.
The thickness is deposited by a sputtering method having a thickness of nm. At this time, Ti
After depositing the N film, without continuously depositing the aluminum alloy film, once opening to the atmosphere and forming a natural oxide film on the surface of the TiN film, depositing the aluminum alloy film, or depositing the TiN film, For example, after performing a heat treatment at a temperature of 650 ° C. for 15 minutes in a nitrogen atmosphere, an aluminum alloy film may be deposited.
Thereafter, the aluminum alloy film 9, buffer layer 8, tungsten film 7, and seed layer 6 are subjected to desired patterning using a known lithography technique and a dry etching technique, thereby forming a second metal wiring pattern.

Although the thickness of the buffer layer 8 is set to 50 nm in this embodiment, if the thickness is increased, the advantage of multi-layering is lost in terms of wiring resistance.

Hereinafter, a detailed description will be given by taking the second metal wiring (700 nm thick) having the structure of this embodiment as an example. In the above configuration, the specific resistance of the tungsten film 7 is about 10 μΩ ·
cm, the specific resistance of the TiN film as the buffer layer 8 is about 6
0 μΩ · cm, the specific resistance of the aluminum alloy film 9 is about 4 μΩ · c
m. Under this condition, the second metal wiring (700 nm)
When the structure of FIG. 1 is a seed layer 6 (50 nm) and a tungsten film 7 (650 nm),
m), the tungsten film 7 (300 nm), the buffer layer 8 and the aluminum alloy film 9, the thicknesses of the buffer layer 8 and the aluminum alloy 9 having the same wiring resistance are determined.
As a result, it is understood that the same wiring resistance is obtained when the buffer layer 8 (200 nm) is the aluminum alloy film 9 (150 nm). That is, the thickness of the buffer layer 8 having a high specific resistance is set to 2
When the thickness is set to 00 nm or more, the thickness of the aluminum alloy film 9 having a low specific resistance is reduced to 15 to make the thickness of the second metal wiring the same.
It is necessary to set the thickness to 0 nm or less, and as a result, the wiring resistance increases. The purpose of reducing the wiring resistance is to make the aluminum alloy film 9 and the tungsten film 7 a multilayer, and if the wiring resistance becomes higher than that of the tungsten film 7 single layer, there is no merit of the multilayer. Therefore, in the case of the above configuration, the thickness of the buffer layer 8 needs to be 200 nm or less.

In the semiconductor device having the above-described structure and the method of manufacturing the same, in order to examine the size of the crystal grain size of the aluminum alloy film, the aluminum alloy film and the tungsten film are subjected to heat treatment in a multilayer structure. FIG. 2 shows a schematic surface view of the crystal grains of the alloy film. FIG. 2A shows the result without the buffer layer of the conventional example shown in FIG.
Is the result for the structure of this embodiment shown in FIG. The impurities in the aluminum alloy film are copper of 0.5% and silicon of 1.0%. The heat treatment condition is 450
° C for 30 minutes. Further, the thickness of the tungsten film 7 is set to 100 nm in order to reduce the influence of the surface unevenness of the tungsten film 7. The thickness of the tungsten film 7 is 1
The surface unevenness at the time of 00 nm was observed by an electron microscope.
It was 5 nm or less, which is the microscope observation limit. As is clear from FIG. 2, the crystal grain size without the buffer layer 8 is about 0.1 to 0.15 μm, whereas the presence of the TiN film as the buffer layer 8 makes the crystal grains smaller. 0.
It becomes as large as 3-0.6 μm. For this reason, the reliability as a wiring is improved.

Here, the surface unevenness of the tungsten film 7 and the surface unevenness of the buffer layer 8 are both 5 nm or less, which is the microscope observation limit, as a result of observation with an electron microscope. This value is
50nm-500nm which is the surface unevenness that has been conventionally said
Much smaller than. This indicates that as a cause of the reliability deterioration, not only the surface unevenness of the tungsten film 7 which has been conventionally known, but also other causes can be considered. From (Chemical Formula 1), the behavior of at least one of fluorine, hydrogen, and HF contained in the tungsten film 7 is considered as one of the causes. In a tungsten film formed by a chemical vapor deposition method and a tungsten film formed by a sputtering method, in addition to the difference in surface unevenness, fluorine (1E20 / cm ³ order), hydrogen, H
The amount of F is greatly different, and many impurities such as fluorine, hydrogen and HF are contained in the tungsten film formed by the chemical vapor deposition method.
Is included. This aluminum alloy film 9 of fluorine, hydrogen and HF
Since the buffer layer 8 prevents the diffusion into the inside, the buffer layer 8 improves the reliability of the wiring.

In the method of manufacturing a semiconductor device as described above, since existing equipment is used, no new equipment investment is required.

In this embodiment, the buffer layer 6
Although a TiN film was used as the above, a Ti film, a TiW film, another high-melting-point metal silicide film, a high-melting-point metal nitride film, or a high-melting-point metal oxide film may be used. The thickness of the second insulating film 4;
The length of the short side of the contact hole 5, the thickness of the seed layer 6, the thickness of the tungsten film 7, the thickness of the buffer layer 8,
The thickness of the aluminum alloy may be another thickness. The same effect can be obtained even if the contact hole 5 has a structure connected to the diffusion layer formed on the silicon substrate 1. Further, a similar effect can be obtained by a structure in which a high melting point metal film or a high melting point metal compound film is formed as an antireflection film on the aluminum alloy film 9.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described as a method of forming the buffer layer 8.
The feature of this embodiment is that, in the method for manufacturing a semiconductor device having the structure shown in FIG. 1, after the tungsten film 7 is formed, the surface of the tungsten film 7 is oxidized by cleaning with sulfuric acid or fuming nitric acid, and Another point is that a tungsten oxide film is formed as the buffer layer 8.

According to the structure of this embodiment, similarly to the first embodiment, the buffer layer 8 prevents diffusion of impurities contained in the tungsten film formed by the chemical vapor deposition method, and the unevenness of the surface of the refractory metal film is reduced. Even if it is large, the crystal grains of the aluminum alloy are not reduced and the electromigration resistance as a wiring is improved. The crystal grains of the aluminum alloy film 9 are 0.2 μm−0.2 μm.
4 μm, which is larger than the case without the tungsten oxide film, and the reliability of the wiring is improved. In addition, since the buffer layer is formed only by performing the washing step, the number of steps is simple as only one step. In addition, since existing equipment is used, there is no need to increase equipment. However, as compared with the TiN film, the tungsten oxide film is an insulating film, so that the resistance between the tungsten film 7 and the aluminum alloy film 9 is higher, so that the contact resistance is higher. Further, the effect as the buffer layer 8 is smaller than that when the buffer layer 8 is formed by oxidation by heat treatment shown in the following third embodiment.

In this embodiment, the tungsten oxide film is formed by washing with sulfuric acid or fuming nitric acid. However, any other material can be used as long as the tungsten film is not dissolved by other oxidizing washing. Also, after forming the tungsten film,
The reliability in the case where a tungsten oxide film is formed as a natural oxide film on the surface of the tungsten film by being exposed to the atmosphere is worse than that of the present embodiment, but is better than the case where there is no natural oxide film.

(Embodiment 3) A third embodiment of the present invention will be described below as a method of forming the buffer layer 8.
The feature of this embodiment is that, in the method for manufacturing a semiconductor device having the structure shown in FIG. 1, after the tungsten film 7 is formed, it is oxidized by performing a heat treatment, and the buffer layer 8 is formed on the tungsten film 7.
To form a tungsten oxide film. Specifically, after forming the tungsten film 7, for example, a heat treatment is performed at a temperature of 400 ° C. for 15 minutes in an atmosphere containing 5% of oxygen. The other gas contained in the atmosphere may be an inert gas such as nitrogen or argon.

According to the structure of this embodiment, the buffer layer 8 prevents diffusion of impurities contained in the tungsten film formed by the chemical vapor deposition method as in the first embodiment, and the unevenness of the surface of the high melting point metal film is reduced. Even if it is large, the crystal grains of the aluminum alloy are not reduced and the electromigration resistance as a wiring is improved. The crystal grain of the aluminum alloy film 9 is 0.3-0.6 μm.
m, and the reliability of the wiring is improved. Also, the second
As compared with the embodiment, since a thicker tungsten oxide film is formed, the reliability is further improved, but the resistance between the tungsten film 7 and the aluminum alloy film 9 increases, and the contact resistance further increases. Get higher.

In this embodiment, the tungsten oxide film is formed by performing a heat treatment at a temperature of 400 ° C. for 15 minutes in an atmosphere containing about 5% of oxygen. The target effect can be obtained by any heat treatment as long as an oxide film is formed.

(Embodiment 4) Hereinafter, a fourth embodiment of the present invention will be described as a method of forming the buffer layer 8.
The feature of this embodiment is that, in the method for manufacturing a semiconductor device having the structure shown in FIG. 1, after the tungsten film 7 is formed, a heat treatment is performed in an ammonia atmosphere or a plasma treatment is performed in a nitrogen atmosphere, so that the tungsten film 7 is nitrided. The point is that a tungsten nitride film is formed as a buffer layer 8 on 7.

According to the structure of this embodiment, similarly to the first embodiment, the buffer layer 8 prevents diffusion of impurities contained in the tungsten film formed by the chemical vapor deposition method, and the unevenness of the surface of the high melting point metal film is reduced. Even if it is large, the crystal grains of the aluminum alloy are not reduced and the electromigration resistance as a wiring is improved. Since the crystal grains of the aluminum alloy film 9 do not become small, the reliability of the wiring is improved. Further, since the tungsten nitride film is a conductive film, the contact resistance does not increase. However, the number of steps increases.

In this embodiment, the tungsten nitride film is formed by performing a heat treatment in an ammonia atmosphere or a plasma treatment in a nitrogen atmosphere. However, a tungsten nitride film of about 5 to 50 nm is formed on the surface of the tungsten film. The desired effect can be obtained under any conditions.

[0042]

As described above, according to the present invention, a high melting point metal film or a high melting point metal film is used as a buffer layer between a high melting point metal film formed by a chemical vapor deposition method and an aluminum alloy film formed by a sputtering method. The presence of the melting point metal compound film prevents this buffer layer from diffusing impurities from the high melting point metal film formed by the chemical vapor deposition method. The particles do not become small and the electromigration resistance as a wiring is improved. In addition, the high-melting-point metal film formed by the chemical vapor deposition method has good coverage, so the reliability of the contact is guaranteed, and the wiring resistance can be reduced by using a multilayer film of the high-melting point metal film and the aluminum alloy film. it can. Further, since the concentration of copper contained in the aluminum alloy film can be reduced, the aluminum alloy film does not corrode, and its practical effect is large.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a main part of a semiconductor device according to a first embodiment of the present invention;

FIG. 2 is a schematic view showing the crystal grain size of an aluminum alloy film in the example and the conventional example.

FIG. 3 is a cross-sectional configuration diagram of a main part of a conventional semiconductor device.

FIG. 4 is a schematic surface view of an aluminum alloy film for explaining electromigration.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2 first insulating film 3 metal wiring 4 second insulating film 5 contact hole 6 seed layer 7 tungsten film 8 buffer layer 9 aluminum alloy film

Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) H01L 21/28-21/288 H01L 21/3205-21/3213 H01L 21/768

Claims (8)

(57) [Claims] 1. A semiconductor device having a metal wiring and a contact hole connected to the metal wiring, wherein: an insulating film on the metal wiring; and a contact hole for connecting to the metal wiring selectively opened in the insulating film. A seed layer on the entire surface of the insulating film and the contact hole; a refractory metal film formed on the seed layer by a chemical vapor deposition method; and a refractory metal film formed by the chemical vapor deposition method on the seed layer. A high melting point metal film or a high melting point metal compound film formed as a buffer layer, and an aluminum alloy film on the buffer layer. 2. A semiconductor device having a diffusion layer and a contact hole connected to the diffusion layer, wherein: an insulating film on the diffusion layer; and a contact hole for connecting to the diffusion layer selectively opened in the insulating film. When,
A seed layer on the entire surface of the insulating film and the contact hole; a refractory metal film formed on the seed layer by a chemical vapor deposition method; and a refractory metal film formed by the chemical vapor deposition method on the seed layer. A semiconductor device comprising: a high melting point metal film or a high melting point metal compound film formed as a buffer layer; and an aluminum alloy film on the buffer layer. 3. A method of manufacturing a semiconductor device having a metal wiring and a contact hole for connecting to the metal wiring, the method comprising: forming an insulating film on the metal wiring; and connecting the insulating film to the metal wiring. Selectively forming a contact hole, forming a seed layer on the entire surface of the insulating film and the contact hole, and forming a refractory metal film on the seed layer by a chemical vapor deposition method. Forming a high melting point metal film or a high melting point metal compound film as a buffer layer on the high melting point metal film formed by the chemical vapor deposition method, and a step of forming an aluminum alloy film on the buffer layer Semiconductor device manufacturing method. 4. A method for manufacturing a semiconductor device having a diffusion layer and a contact hole for connecting to the diffusion layer, the method comprising: forming an insulating film on the diffusion layer; and connecting the insulating film to the diffusion layer. Selectively forming a contact hole, forming a seed layer on the entire surface of the insulating film and the contact hole, and forming a refractory metal film on the seed layer by a chemical vapor deposition method. Forming a high melting point metal film or a high melting point metal compound film as a buffer layer on the high melting point metal film formed by the chemical vapor deposition method, and a step of forming an aluminum alloy film on the buffer layer Semiconductor device manufacturing method. 5. The semiconductor device according to claim 1, wherein the buffer layer is a titanium nitride (TiN) film or a titanium tungsten (TiW) film. 6. A step of forming a high melting point metal film by chemical vapor deposition according to claim 3 or 4, followed by washing with sulfuric acid or fuming nitric acid to form a high melting point metal film surface as a buffer layer. A method for manufacturing a semiconductor device, comprising a step of forming a melting point metal oxide film. 7. A heat treatment is performed after the step of forming a refractory metal film by the chemical vapor deposition method according to claim 3 or 4, whereby a refractory metal oxide film is formed as a buffer layer on the surface of the refractory metal film. A method for manufacturing a semiconductor device comprising a step of forming. 8. The method according to claim 3, wherein after the step of forming the high melting point metal film by the chemical vapor deposition method, a heat treatment is carried out in an ammonia atmosphere or a plasma treatment is carried out in a nitrogen atmosphere. A method for manufacturing a semiconductor device, comprising a step of forming a refractory metal nitride film as a buffer layer on a surface of a metal film.