JPH09186101A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a reliable contact on an Al-made electrode or wiring by terminating the surface of Al or Al-based material with halogen and forming a conductive material-made contact on this surface. SOLUTION: To form a contact on an Al work, a contact forming surface is light etched by an etchant, typically hydrofluoric acid, to thereby terminate the exposed surface of the Al work with halogen. For example, after forming a contact hole of an Al-made gate electrode 110, an oxide film naturally formed on this surface is removed by a wet treatment and a Ni film 119 is formed by the electroless plating at the same time, thereby ensuring a reliable contact of the electrode 110 with a lead-out wiring.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD [0001] The invention disclosed in the present specification is:
The present invention relates to a technique of forming a contact for wiring on an electrode or a wiring mainly containing aluminum or aluminum.

[0002]

2. Description of the Related Art A thin film transistor manufactured by a manufacturing process as shown in FIG. 5 is known. The thin film transistor shown in FIG. 5 is formed on a glass substrate.
It has a characteristic of small FF current. The small OFF current is a very important factor when used in an active matrix type liquid crystal display device and other thin film integrated circuits.

The thin film transistor shown in FIG. 5 improves the OFF current characteristics by forming an electrical buffer region called an offset gate region between the channel forming region and the source / drain regions. The configuration as shown in FIG. 5 is described in, for example, Japanese Patent Laid-Open No. 4-360580.

The manufacturing process of the thin film transistor shown in FIG. 5 will be briefly described below. First, prepare the glass substrate 201,
A silicon oxide film 202 is formed on the surface by sputtering or plasma CVD. This silicon oxide film is a base film for preventing impurities and the like from diffusing from the glass substrate. Then, an amorphous silicon film is formed by a plasma CVD method or a low pressure thermal CVD method.

If necessary, heat treatment or laser light irradiation is performed to crystallize the amorphous silicon film to obtain a crystalline silicon film. Note that the amorphous silicon film may be used as it is if the low characteristics are allowed.

Next, the amorphous silicon film is patterned to form the active layer 203 of the thin film transistor.
After forming the active layer 203, a silicon oxide film 204 functioning as a gate insulating film is formed by a plasma CVD method or a sputtering method. Then, a film of aluminum is formed,
By further patterning, the gate electrode 20
5 is formed. This gate electrode 205 is called a first layer wiring. (FIG. 5 (A))

Next, the gate electrode 20 is placed in the electrolytic solution.
Anodic oxidation is performed using 5 as an anode to form an anodic oxide film 206 around the gate electrode 205. In the structure of the thin film transistor shown in FIG. 5, the technique of forming the anodic oxide film 206 is an important point. (FIG. 5 (B))

Then, as shown in FIG.
Impurity ions (here, P (phosphorus) ions) for forming the drain region are implanted by an ion implantation method or a plasma doping method.

In this step, the gate electrode 205 and the surrounding anodic oxide film 206 serve as a mask, and impurity ions are not implanted below it. Also, 207 and 210
Impurity ions are implanted into the region. As a result, 2
07 can be a source region and 210 can be a drain region. Then, the region 20 into which the impurity ions are not implanted
8 can be an offset gate region. Further, the region 209 can be used as a channel formation region.

Since the impurity ion implantation step shown in FIG. 5C can be performed in a self-aligned manner, complicated steps such as mask alignment are not required and the productivity is extremely excellent.
Further, it is possible to obtain a device having no variation in characteristics among the elements.

After the ion implantation step shown in FIG. 5C, a silicon oxide film 211 is formed as an interlayer insulating film. And
Contact holes are formed, and a source electrode 212 and a drain electrode 213 are formed. At the same time, the gate electrode 2
The lead electrode 214 from 05 is formed.

In the drawing, the source / drain electrode 2
12 and 213 and the extraction electrode 2 from the gate electrode 205
Although it is described that 14 and 14 are formed in the same vertical cross section, the extraction electrode 214 from the gate electrode 205 is actually present on the front side or the other side in the drawing. The lead-out electrodes from these source / drain electrodes and gate electrodes are called second-layer wiring.

The thin film transistor whose manufacturing process is shown in FIG. 5 is excellent in its characteristics and the method of manufacturing the offset gate region. Further, when considering a large-area active matrix type liquid crystal display device and other large-scale integrated circuits, the use of aluminum for the gate electrode is very useful in terms of reducing the wiring resistance.

In the structure shown in FIG. 5, the gate electrode and the gate wiring are covered with a dense anodic oxide film having a high breakdown voltage, so that leakage and interaction with various wirings formed on the interlayer insulating film are prevented. It also has the advantage that the problem can be greatly improved.

As described above, although the thin film transistor shown in FIG. 5 is very useful, it faces an extremely difficult situation in the process shown in FIG. 5 (D). In the step shown in FIG. 5D, the source / drain electrodes 212, 21
Formation of contact hole for 3 and gate electrode 20
The formation of contact holes for the No. 5 extraction electrode 214 must be performed.

In forming the contact holes for the source / drain electrodes 212 and 213, since the films that must be removed are the silicon oxide film 211 and the silicon oxide film 204, a hydrofluoric acid-based etchant such as buffer hydrofluoric acid is used. It can be performed relatively easily by wet etching using (BHF).

Since buffer hydrofluoric acid has a remarkably small etching rate with respect to silicon as compared with an etching rate with respect to silicon oxide, the etching can be completed in a state where the etching has proceeded to the active layer 203. That is, the active layer 203 can be used as an etching stopper.

Further, in forming a contact hole for the electrode 214 for extraction, a silicon oxide film 211 and an aluminum oxide layer (Al ₂ formed by anodic oxidation) are formed.
206 (based on O ₃ ) must be etched. This etching is also performed using buffer hydrofluoric acid.

Oxide layer 2 using a hydrofluoric acid-based etchant
The etching state of 06 is shown in FIG. First, FIG. 6 (A)
As shown in FIG. 4, the hydrofluoric acid-based etchant (eg, buffer hydrofluoric acid) silicon oxide film 211 is etched. Then, the aluminum oxide layer 206 is etched.

However, the gate electrode 2 made of aluminum
05 is exposed, the surface of the oxide layer 302 is extremely thin.
Is formed. This oxide layer 302 becomes a presence that obstructs electrical contact during the subsequent contact formation.

Such an extremely thin oxide layer is easily formed by contact with air, and it is very difficult to eliminate the formation.

[0022]

Use of the gate electrode made of aluminum as described above has the following significance.

(1) Since the resistance of the electrodes can be reduced, an element suitable for high speed operation can be formed. In particular, when forming a gate wiring extending from the gate electrode, it is useful to be able to reduce the wiring resistance.

(2) The offset gate region can be formed in a self-aligned manner in the ion implantation step by using the aluminum oxide layer formed around the gate electrode as a mask.

(3) It is possible to improve the reliability by reducing the short circuit between the upper and lower sides of wiring and crosstalk.

On the other hand, on the other hand, there is a problem that the oxide layer formed on the surface of aluminum becomes an obstacle to the contact when forming the contact hole for the gate electrode made of aluminum, while having the significance as described above. .

This problem becomes particularly serious when aluminum and aluminum are contacted.

The invention disclosed in this specification aims to solve this problem. That is, it is an object to solve the problem of contact failure due to the presence of an oxide layer, which is a problem when aluminum is used for an electrode or a wiring.

[0029]

One of the inventions disclosed in the present specification is a step of terminating aluminum or a surface containing aluminum as a main component with a halogen element, and a step of forming a contact with a conductive material on the surface. And are included.

According to another aspect of the present invention, the step of forming a metal film on the surface containing aluminum or aluminum as a main component, and the step of removing the metal film with an etchant containing a halogen element, and at the same time mainly using the aluminum or aluminum. It is characterized by including a step of terminating the surface as a component with a halogen element and a step of forming a contact made of a conductive material on the surface.

The state in which the surface of the aluminum film is terminated by the halogen element is confirmed from FIG.

FIG. 8 shows the result of Auger analysis. FIG.
(A) is a result of analysis of the surface of the aluminum film after removing the anodic oxide film formed on the surface of the aluminum film with chromium mixed acid. As can be seen from the figure, the peak of chromium (Cr) clearly appears.

On the other hand, (B) shows that after the removal of the anodic oxide film by the chromium mixed acid, 1% hydrofluoric acid was added,
It is a measurement result in a state where the passivation film formed on the surface of the aluminum film is removed. As is clear from (B), the peak of chromium disappears, and the peak appears in fluorine (F) instead.

This is interpreted as indicating that the outermost surface of the aluminum film was terminated by fluorine by the hydrofluoric acid treatment.

According to another aspect of the present invention disclosed in this specification, the oxide film formed on the surface containing aluminum or aluminum as a main component is washed with a solution containing metal ions to remove the oxide film. It is characterized in that a film of the metal is formed on the surface.

According to another aspect of the invention, a step of forming a gate electrode with aluminum or a material containing aluminum as a main component, a step of forming an insulating film covering the gate electrode, and a contact hole formed in the insulating film. And exposing the gate electrode, and forming a metal film on the surface of the exposed gate electrode using a solution containing metal ions.

In the above structure, a component for removing the oxide film formed on the surface of the gate electrode is contained in the solution, and the oxide film formed on the surface of the gate electrode is removed simultaneously with the formation of the metal film. It is useful.

According to another aspect of the invention, one of aluminum or a material containing aluminum as a main component and the other aluminum or a material containing aluminum as a main component is used as one of the aluminum or a material containing aluminum as a main component. The method is characterized by including a step of connecting through a metal film deposited on the surface.

According to another aspect of the invention, aluminum or a material containing aluminum as a main component, a first metal material,
Is connected through a metal film made of a second metal material deposited on the surface of the aluminum or a material containing aluminum as a main component.

In the above structure, the metal film is preferably deposited at the same time as the removal of the oxide film formed on the surface of aluminum or a material containing aluminum as a main component.

As a means for forming the metal film in the invention disclosed in this specification, electroless plating is preferably used.

[0042]

[Function] When forming a contact with aluminum, the surface to be contacted is light-etched by using an etchant typified by hydrofluoric acid to terminate the exposed surface of aluminum with a halogen element. You can

By doing so, it is possible to suppress the formation of an oxide film on the surface of aluminum, and it is possible to form a good ohmic contact when forming a contact later. Since the halogen element is removed when the contact is formed, its presence does not adversely affect the formation of the contact.

By forming a nickel film on the surface of aluminum by electroless plating, it is possible to eliminate the influence of the natural oxide film formed on the surface of aluminum. Particularly, the adverse effect of the natural oxide film formed on the aluminum surface can be eliminated by performing the electroless plating at the same time as the cleaning step for removing the natural oxide film formed on the aluminum surface. Then, it is possible to surely obtain electrical contact between the aluminums, or between the aluminum and another metal or conductor, and further with the semiconductor.

[0045]

【Example】

[Embodiment 1] In this embodiment, a manufacturing process of a thin film transistor having a low OFF current characteristic formed over a glass substrate will be described. A manufacturing process of the thin film transistor shown in this embodiment of FIGS. 1 to 3 will be described.

First, as shown in FIG. 1A, the glass substrate 1
01 as a base film and a silicon oxide film 102 of 2000 Å thickness
Is formed by a sputtering method or a plasma CVD method.

Although it is expensive, a quartz substrate may be used instead of the glass substrate.

Next, an amorphous silicon film (amorphous silicon film) (not shown) is formed to a thickness of 500Å. As a film forming method, a plasma CVD method or a low pressure thermal CVD method is used. This amorphous silicon film is later crystallized into a crystalline silicon film.
Note that film formation by a low pressure thermal CVD method is desired in terms of good film quality.

Next, the amorphous silicon film is crystallized by a heat treatment, laser light irradiation, or a combination thereof to obtain a crystalline silicon film. Then, by patterning this crystalline silicon film, an island-shaped region 103 to be an active layer of a thin film transistor later is formed.

Further, a silicon oxide film forming the gate insulating film 104 is formed by sputtering or plasma CVD by 10
A film is formed to a thickness of 00 °.

Thus, the state shown in FIG. 1A is obtained.

Next, as shown in FIG. 1B, an aluminum film 105 having a thickness of 5000Å is formed by a sputtering method.
Scandium is contained in the aluminum film in an amount of 0.1% by weight in order to suppress the formation of hillocks and whiskers in the subsequent steps.

Hillocks and whiskers are spine-like or needle-like protrusions due to abnormal growth of aluminum.

Next, a dense anodic oxide film is formed on the surface of the aluminum film 105. Here, 3% as the electrolytic solution
An ethylene glycol solution containing tartaric acid obtained in 1 above is neutralized with ammonia. Then, in the electrolytic solution, anodization is performed by using the aluminum film 105 as an anode to form an anodized film 106.

This anodic oxide film has a dense film quality and functions to enhance the adhesion to the resist mask formed later. The thickness of the anodic oxide film 106 may be about 100 Å. The thickness of the dense anodic oxide film 106 can be controlled by the applied voltage.

Next, as shown in FIG. 1C, a resist mask 107 is arranged, and the aluminum film 105 and the anodic oxide film 106 on the surface thereof are etched.

When the state shown in FIG. 1C is obtained, anodic oxidation is performed again in a 3% oxalic acid aqueous solution. In this anodic oxidation process, a porous anodic oxide film is formed in the state shown by 108. This is because the resist mask 107 and the dense anodic oxide film 106 exist. Thus, the state shown in FIG. 1D is obtained.

The growth distance of this porous anodic oxide film is 5
000Å. The porous anodic oxide film 108
Can be controlled by the anodizing time.

After that, the resist mask 107 and the dense anodic oxide film 106 are removed. Then, again, anodic oxidation is performed by using an ethylene glycol solution containing 3% tartaric acid neutralized with ammonia as an electrolytic solution.

In this anodic oxidation step, since the electrolytic solution penetrates into the porous anodic oxide film 108, a dense anodic oxide film is formed as indicated by 109. Here, the thickness of the dense anodic oxide film indicated by 109 is 600Å
And

Thus, the state shown in FIG. 1 (E) is obtained. In this state, the gate electrode 110 made of aluminum is defined. Although not clear from the figure, a gate wiring is formed at the same time extending from this gate electrode.

The resistance value can be lowered by forming the electrodes and wirings using such aluminum. This is very useful when a fine circuit has to be formed in a large area like an active matrix type liquid crystal display device.

Next, the exposed gate insulating film (silicon oxide film)
Remove 104. And the remaining gate insulating film 111
Get.

To etch the silicon oxide film, a hydrofluoric acid-based etchant such as hydrofluoric acid or buffer hydrofluoric acid (B
HF), hydrofluoric acid or buffer hydrofluoric acid to which acetic acid has been added, or these hydrofluoric acid-based etchants to which a surfactant has been added.

As the buffer hydrofluoric acid, a mixture of 10 parts of ammonium fluoride and 1 part of hydrofluoric acid can be used. Since these hydrofluoric acid-based etchants have a significantly higher etching rate for silicon oxide or aluminum than the etching rate for silicon, a material made of silicon oxide or aluminum (or a material containing these materials as a main component) is selectively used. It is a useful etchant when it is removed or when a contact hole is formed in these materials.

Further, as the etching of the silicon oxide film, dry etching using a fluorine-based gas such as CF ₄ or CHF ₃ may be used.

Thus, the state shown in FIG. 1 (E) is obtained. Next, the porous anodic oxide film 108 is removed. Thus, the state shown in FIG. 2A is obtained.

In the state shown in FIG. 2A, implantation of impurity ions for imparting N type or P type is performed. Here, P (phosphorus) ions are implanted in order to manufacture an N-channel thin film transistor.

In this step, impurity ions are implanted in a high concentration in the regions 112 and 116, and 113 and 115 are formed.
Impurity ions are implanted at a low concentration in the region indicated by.
This is because the remaining gate insulating film 111 functions as a semitransparent mask.

Impurity ions are not implanted in the region 114. As a result, the region of 114 is defined as the channel forming region.

After the implantation of the impurity ions, laser light irradiation is carried out to activate and anneal the region where the impurity ions are previously implanted.

As a result, the source region 112, the drain region 116, the low concentration impurity regions 113 and 115, and the channel forming region 114 are formed. Here, the low-concentration impurity region 115 becomes a region called an LDD (lightly doped drain) region.

Next, as shown in FIG. 2B, the interlayer insulating film 1
17 is formed into a film. Here, a silicon oxide film formed by a plasma CVD method is used as the interlayer insulating film 117.

Next, as shown in FIG. 2C, the source region 1
12, the drain region 116, and the gate electrode 110.
A contact hole is formed in (or the gate wiring extending from).

Here, the interlayer insulating film is first removed by buffer hydrofluoric acid, and then the dense anodic oxide film 1 is formed by the dry etching method using HBr gas and methanol.
09 is removed. (Fig. 2 (C))

Further, a nickel film is formed by electroless plating. Here, electroless plating is performed at the same time as the wet treatment after dry etching to form a nickel film on the surface of the aluminum film.

This wet treatment also serves as a step of removing the natural oxide film formed on the surface of the exposed aluminum.

When electroless plating is used, a nickel film can be selectively formed on aluminum.
As shown in FIG. 2D, a film made of nickel denoted by 118 to 120 can be selectively formed. The thickness of the nickel film may be typically about 10 to 100Å.

The formation of the nickel film by the electroless plating is carried out at the same time as removing the extremely thin oxide film (natural oxide film) which is inevitably formed on the surface of aluminum. In general, the influence of the natural oxide film formed on the surface of the nickel film can be ignored, so that the final contact can be ensured.

Then, as shown in FIG. 3A, an electrode (wiring) made of aluminum is formed. Here, a nickel film 119 is formed on the surface of the gate electrode 110 made of aluminum.
Is deposited by electroless plating, it is possible to improve the contact between the gate electrode 110 made of aluminum and the extraction electrode 122 made of aluminum.

On the other hand, 121 and 123 are a source electrode (source wiring) and a drain electrode (drain wiring), respectively. These electrodes are formed on the source region and the drain region through the nickel film 118 or 120. Such a structure has no influence on the operation of the thin film transistor.

In this example, aluminum was used as the extraction electrodes denoted by reference numerals 121 to 123. However, a laminated film of a titanium film, an aluminum film, and a titanium film may be used for better contact.

Even in such a case, the nickel layer 1
The presence of 19 makes it possible to obtain good contact between the gate electrode 110 made of aluminum and the extraction electrode 122.

[Embodiment 2] This embodiment shows a manufacturing process when a thin film transistor having a structure similar to that of the first embodiment is arranged in a pixel region of an active matrix liquid crystal display device.

First, up to the state shown in FIG. 2B, a thin film transistor is manufactured according to the same manufacturing steps as those shown in the first embodiment.

Next, as shown in FIG. 4A, the source region 1
12 and the gate electrode 110 are formed with contact holes, and the nickel layer 40 is formed by electroless plating.
1 and 402 are formed.

Then, as shown in FIG. 4B, lead electrodes 403 and 404 made of aluminum are formed. At this time, the presence of the nickel layer 402 enables good contact between the lead electrode 404 made of aluminum and the gate electrode 110 made of aluminum.

Further, a second interlayer insulating film 405 is formed by using a transparent resin material. Acrylic resin or polyimide is used as the resin material forming the second interlayer insulating film.

The thickness of the second interlayer insulating film is increased to several μm or more. Further, since it is a resin material, its surface can be made flat. The ability to make the surface flat becomes important when the liquid crystal layer is formed on the surface later.

Thus, the state shown in FIG. 4C is obtained. Next, a contact hole is formed in the source region 116, and a pixel electrode 406 made of ITO is formed.

The pixel electrode 406 is patterned so as to cover above the thin film transistor. Such a configuration is not generally preferable because it increases unnecessary capacity. However, this problem can be avoided by increasing the thickness of the interlayer insulating film 405 to about several μ or more.

Also in the case of adopting the configuration of this embodiment, it is possible to ensure the contact between the gate electrode made of aluminum and the lead-out electrode made of aluminum as well.

[Embodiment 3] This embodiment relates to a structure in which a contact of a gate electrode made of aluminum is obtained by a method different from those of the other embodiments. FIG. 7 shows a manufacturing process of this example. First, the state shown in FIG. 7A is obtained according to the manufacturing process shown in FIGS. The manufacturing process of each part is the same as that shown in FIGS. 1 and 2 unless otherwise specified.

The state shown in FIG. 7A shows a state in which a silicon oxide film 117 is formed as an interlayer insulating film.

After obtaining the state shown in FIG. 7A, the contact openings 701 and 70 are formed by dry etching.
2, 703 are formed. In this state, an opening 701 to the source region and an opening 703 to the drain region are formed. Further, the opening to the gate electrode is formed by the anodic oxide film 10.
9 is exposed.

Thus, the state shown in FIG. 7B is obtained. Next, the anodic oxide film 109 is removed using a chromium mixed acid.
The chromium mixed acid is a solution obtained by mixing acetic acid, nitric acid, phosphoric acid, water, and a chromic acid aqueous solution, and has a function of selectively removing aluminum oxide.

When the anodic oxide film 109 is removed using chromium mixed acid, a chromium film (extremely thin film) is formed on the surface of the aluminum film. At the same time, a passivation film is formed. Specifically, the passivation film is formed on the surface of the aluminum film, and the chromium film is further formed thereon.

This film is represented by 70 in FIG.
Shown at 4. In this state, the passivation film is removed using hydrofluoric acid. At this time, the chromium film is also removed at the same time. Then, the surface of the aluminum film is terminated by the fluorine atoms. This effect can be obtained even when another halogen element such as chlorine is used.

After removing the passivation film, electrodes 705, 70 made of a laminated film of a titanium film, an aluminum film and a titanium film.
6, 707 are formed. At this time, since the exposed surface of the gate electrode 110 serving as a contact is terminated (terminated) by fluorine atoms, it is possible to suppress the formation of an oxide film at that portion. Then, the contact between the electrode 706 and the gate electrode 110 can be made to have good ohmic contact.

[0100]

By utilizing the invention disclosed in this specification, it is possible to solve the problem of contact failure, which is a problem when aluminum is used for wirings and electrodes.

The use of aluminum as a wiring or an electrode is very useful in that its resistance can be reduced, and the practical effects thereof can be made extremely high by obtaining the above effects. .

INDUSTRIAL APPLICABILITY The invention disclosed in this specification is useful for an active matrix type liquid crystal display device having a large area which requires low resistance electrodes and wiring.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a manufacturing process of a thin film transistor.

2A to 2D are diagrams showing an outline of a manufacturing process of a thin film transistor.

FIG. 3 is a diagram showing an outline of a manufacturing process of a thin film transistor.

FIG. 4 is a diagram showing an outline of a manufacturing process of a thin film transistor.

FIG. 5 is a diagram showing a conventional manufacturing process of a thin film transistor.

FIG. 6 is a diagram showing a state in which a contact of a gate electrode portion is formed.

FIG. 7 illustrates a manufacturing process of a thin film transistor.

FIG. 8 is a diagram showing a result of Auger analysis.

[Explanation of symbols]

101 glass substrate 102 base film (silicon oxide film) 103 active layer (crystalline silicon film) 104 gate insulating film (silicon oxide film) 105 aluminum film 106 dense anodic oxide film 107 resist mask 108 porous anodic oxide film 109 Dense anodic oxide film 110 Gate electrode 111 Remaining gate electrode 112 High-concentration impurity region (source region) 113 Low-concentration impurity region 114 Channel formation region 115 Low-concentration impurity region (LDD)
Region) 116 drain region 117 interlayer insulating film (silicon oxide film) 118, 119, 120 nickel film 121 formed by electroless plating 121 source electrode 122 extraction electrode from gate electrode 123 drain wiring 401, 402 formed by electroless plating Nickel film 403 Source electrode 404 Gate electrode extraction electrode 405 Interlayer insulating film (transparent resin material) 406 Pixel electrode (ITO electrode) 701, 702, 703 Contact opening 704 Laminated film of passivation film and chromium film 705 , 706, 707 electrodes

Claims (9)

[Claims] 1. A method of manufacturing a semiconductor device, comprising: a step of terminating aluminum or a surface containing aluminum as a main component with a halogen element; and a step of forming a contact made of a conductive material on the surface. 2. A step of forming a metal film on aluminum or a surface containing aluminum as a main component, and the step of removing the metal film with an etchant containing a halogen element and at the same time removing the surface containing aluminum aluminum or a main component of aluminum. A method of manufacturing a semiconductor device, comprising: a step of terminating with a halogen element; and a step of forming a contact made of a conductive material on the surface. 3. An oxide film formed on a surface containing aluminum or aluminum as a main component is washed with a solution containing metal ions to remove the oxide film and form a film of the metal on the surface. A method for manufacturing a semiconductor device, comprising: 4. A step of forming a gate electrode with aluminum or a material containing aluminum as a main component, a step of forming an insulating film so as to cover the gate electrode, and a step of forming a contact hole in the insulating film to form the gate electrode. And a step of forming a metal film on the surface of the exposed gate electrode using a solution containing metal ions. 5. The oxide film formed on the surface of the gate electrode as claimed in claim 4, wherein the solution contains a component that removes the oxide film formed on the surface of the gate electrode. A method for manufacturing a semiconductor device, comprising: 6. A method of manufacturing a semiconductor device according to claim 3, further comprising the step of forming a contact in contact with the metal film. 7. One of aluminum or a material containing aluminum as a main component and another aluminum or a material containing aluminum as a main component are deposited on the surface of the one aluminum or a material containing aluminum as a main component. A method of manufacturing a semiconductor device, comprising a step of connecting via a metal film. 8. A metal film comprising aluminum or a material containing aluminum as a main component, a first metal material, and a second metal material deposited on the surface of the aluminum or a material containing aluminum as a main component. A method for manufacturing a semiconductor device, which has a step of connecting via a semiconductor device. 9. The method for manufacturing a semiconductor device according to claim 8, wherein the deposition of the metal film is performed simultaneously with the removal of the oxide film formed on the surface of aluminum or a material containing aluminum as a main component.