JPH05218025A - Method of manufacturing semiconductor device - Google Patents

Abstract

(57) [Abstract] [Object] A method for manufacturing a semiconductor device, and more particularly, a method for forming a wiring having an anodic oxide film, and an object thereof is a method for forming a wiring in which the anodic oxide film does not overhang. A process of forming a conductive film 3 on an insulating film 2 on a semiconductor substrate 1 and then anodizing the surface to form an anodized film 4, and using a mask 5 formed on the anodized film 4 as a mask. And selectively removing the anodic oxide film 4 by etching, and by heating the end portions of the mask 5 to flow to form the sagging mask 5a that covers the side surfaces of the anodizing film 4, the sagging mask 5a is removed. A step of isotropically etching the conductive film 3 using the mask and removing the conductive film 3 without exposing the anodic oxide film 4, and the conductive film wiring 3c whose upper surface is covered with the anodic oxide film 4 Are formed.

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, and more particularly to a method of forming a wiring having an anodic oxide film.

At present, multilayer wiring is widely used in semiconductor devices. In multi-layered wiring, an anodic oxide film is formed on the surface for the purpose of preventing hillocks from occurring in the wiring and improving the service life of the wiring.

[0003]

2. Description of the Related Art FIGS. 5A to 5E are sectional views in order of steps showing a conventional example of forming a wiring having an anodic oxide film, and the conventional example will be described below with reference to these drawings.

Referring to FIG. 5 (a), reference numeral 1 is a Si substrate on which elements have been formed, on which a SiO ₂ film 2 is formed as an insulating film, and an AlCu film 3 is deposited thereon. By anodizing the surface of the AlCu film 3,
An anodic oxide film 4 of about 500 Å is formed.

Referring to FIG. 5B, a resist mask 5 for forming wiring is formed on the anodic oxide film 4. See FIG. 5C. The anodic oxide film 4 is etched and removed using the resist mask 5 as a mask. The etching solution is, for example, a mixed solution of acetic acid and ammonium hydrogen fluoride.

See FIG. 5 (d). AlC using the resist mask 5 and the anodic oxide film 4 as a mask.
The u film 3 is removed by etching to form the wiring 3a. The etching solution is phosphoric acid, for example.

Referring to FIG. 5 (e), the resist mask 5 is peeled off. In this way, the wiring having the anodic oxide film 4 on the surface is formed, but the eaves 4a are generated in the anodic oxide film 4 by the side etching of the AlCu film 3. When the eaves 4a occurs, various problems caused by it occur.

6 (a) and 6 (b) are sectional views for explaining the problems of the conventional example. 6 is an interlayer insulating film, for example PSG
A film 7 is an upper layer wiring, for example, an AlCu film. If the anodic oxide film 4 has an eaves 4a, an interlayer insulating film formed thereon,
For example, the PSG film 6 grows abnormally (see FIG. 6 (a)).

When the PSG film 6 grows abnormally, the upper wiring formed on the PSG film 6, for example, the AlCu film 7, may have poor coverage, and cracks 7a may occur around the eaves 4a, resulting in poor connection (FIG. 6 (b). )).

Further, if the anodic oxide film 4 has the eaves 4a, that portion is peeled off to have an indefinite shape, and abnormal growth easily occurs in the interlayer insulating film grown thereon.

[0011]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a wiring forming method in which an eaves on the anodic oxide film on the wiring is not formed.

[0012]

1 (a) to 1 (e) are process sectional views showing a first embodiment, and FIGS. 2 (a) to 2 (i) are process steps showing a second embodiment. Sectional views and FIGS. 3A to 3F are sectional views in order of steps showing a third embodiment.

The above-mentioned problems are formed by forming the conductive film 3 on the insulating film 2 on the semiconductor substrate 1 and then anodizing the surface to form the anodic oxide film 4, and forming the anodic oxide film 4 on the surface. A step of selectively etching and removing the anodic oxide film 4 using the mask 5 as a mask; and an isotropic etching and removing the conductive film 3 using the mask 5 as a mask, and then performing side etching. The exposed anodic oxide film 4 is removed by etching, and the problem is solved by a method for manufacturing a semiconductor device in which a conductive film wiring 3a whose upper surface is covered with the anodic oxide film 4 is formed.

Further, a step of forming a conductive film 3 on the insulating film 2 on the semiconductor substrate 1 and thereafter anodizing the surface to form an anodized film 4, and a mask 5 formed on the anodized film 4.
A step of selectively etching and removing the anodic oxide film 4 by using the mask as a mask, and after forming a sloping mask 5a covering the side surface of the anodic oxide film 4 by flowing the end portion of the mask 5 by heating. , The conductive film 3 using the sagging mask 5a as a mask
Isotropically etched to remove the conductive film 3 without exposing the anodic oxide film 4, and a wiring 3c of a conductive film whose upper surface is covered with the anodic oxide film 4 is formed. This is solved by the method of manufacturing the device.

Further, a step of forming a conductive film 3 on the insulating film 2 on the semiconductor substrate 1 and then anodizing the surface to form an anodized film 4, and a mask 5 formed on the anodized film 4.
A step of selectively etching and removing the anodic oxide film 4 by using the mask as a mask, and after forming a sloping mask 5a covering the side surface of the anodic oxide film 4 by flowing the end portion of the mask 5 by heating. , The conductive film 3 using the sagging mask 5a as a mask
Of the conductive film whose upper surface is covered with the anodic oxide film 4 is removed by isotropically etching and then removing the part of the anodic oxide film 4 exposed by side etching. This is solved by a method for manufacturing a semiconductor device forming 3f.

[0016]

When the conductive film 3 is etched, if the portion of the anodic oxide film 4 exposed by side etching is left as it is, an eave of the anodic oxide film will occur on the wiring in the future, but in the present invention, that portion is etched. Since there is a step of removing the anodic oxide film, the eaves of the anodized film will not be formed on the wiring in the future.

Further, since the end portion of the mask 5 is made to flow by heating to form the sagging mask 5a covering the side surface of the anodic oxide film 4, even if the conductive film 3 is side-etched,
It is possible to prevent the anodic oxide film 4 from being exposed.
When the side etching progresses and the anodic oxide film 4 is about to be exposed, the etching is stopped, and the end portion of the mask 5a that is dripping is made to flow again by heating to increase the thickness of covering the side surface of the anodic oxide film 4. The etching of the conductive film 3 may be continued. By etching the conductive film 3 in this manner, the eaves of the anodic oxide film is not formed on the wiring.

Further, even if the side etching progresses and the anodic oxide film 4 is exposed, there is a step of etching and removing the exposed part of the anodic oxide film, so that the eaves of the anodic oxide film may be formed on the wiring. Absent.

[0019]

Embodiments FIGS. 1A to 1E are sectional views in order of steps showing a first embodiment. The first embodiment will be described below with reference to these drawings.

Referring to FIG. 1 (a), 1 is a Si substrate on which elements have been formed, on which a SiO ₂ film 2 having a thickness of, for example, 4000 Å is formed as an insulating film,
On top of that, as a conductive film, for example, AlC with a thickness of 1.1 μm
The u film 3 is deposited. The surface of the AlCu film 3 is anodized to form an anodized film 4 having a thickness of about 500Å.

Referring to FIG. 1B, a resist mask 5 for forming wiring is formed on the anodic oxide film 4. The anodic oxide film 4 is etched and removed using the resist mask 5 as a mask. The etching solution is, for example, a mixed solution of acetic acid and ammonium hydrogen fluoride.

Referring to FIG. 1 (c), using the resist mask 5 and the anodic oxide film 4 as a mask, AlC
The u film 3 is removed by etching to form the wiring 3a. For etching, for example, using a mixed solution of phosphoric acid, acetic acid, and nitric acid,
Etch at 50 ° C. At this time, due to the side etching of the AlCu film 3, the eaves 4a is generated on the anodic oxide film 4.

Referring to FIG. 1D, the eaves 4a is isotropically dry-etched with CF ₄ gas and removed. Instead of dry etching, wet etching using a mixed solution of acetic acid and ammonium hydrogen fluoride may be adopted.

Referring to FIG. 1E, the resist mask 5 is peeled off. In this way, the wiring 3a covered with the anodic oxide film 4 and having no eaves of the anodic oxide film was formed.

FIGS. 2A to 2I are sectional views in order of the processes, showing the second embodiment. Below, with reference to these figures, the second
An example will be described. Refer to FIG. 2 (a). 1 is a Si substrate on which element formation has been completed, on which a SiO ₂ film 2 having a thickness of, for example, 4000 Å is formed as an insulating film,
On top of that, as a conductive film, for example, AlC with a thickness of 1.1 μm
The u film 3 is deposited. The surface of the AlCu film 3 is anodized to form an anodized film 4 having a thickness of about 500Å.

Referring to FIG. 2B, a resist mask 5 for forming wiring is formed on the anodic oxide film 4. The anodic oxide film 4 is etched and removed using the resist mask 5 as a mask. The etching solution is, for example, a mixed solution of acetic acid and ammonium hydrogen fluoride.

The process up to this point is the same as in the first embodiment. See Fig. 2 (c). Bake at 175 ° C for 20 minutes and apply resist mask 5
The edge portion of is flowed to form a sagging resist mask 5a. After that, the surface of the AlCu film 3 is hit with oxygen plasma for 30 seconds to increase hydrophilicity.

Referring to FIG. 2D, the AlCu film 3 is etched using the mask 5a as a mask. The etching liquid is, for example, a mixed liquid of phosphoric acid, acetic acid, and nitric acid, and the liquid temperature is 50 ° C. and the etching time is 30 seconds. 3b represents the AlCu film after etching,
Due to the side etching of the Cu film, the etching is interrupted before the anodic oxide film 4 is exposed.

See FIG. 2 (e). Baking again at 175 ° C. for 20 minutes to remove the mask
The edge of 5a is further flowed to form a sagged resist mask 5b. After that, the surface of the AlCu film 3 is hit with oxygen plasma for 30 seconds to increase hydrophilicity.

Referring to FIG. 2F, the AlCu film 3b is etched using the mask 5b as a mask. The etching solution is, for example, a mixed solution of phosphoric acid, acetic acid and nitric acid, and the solution temperature is 50 ° C. and the etching time is 90 seconds. Anodic oxide film 4 by side etching of AlCu film
Before the wiring is exposed, the etching for forming the wiring is almost completed. 3c is an AlCu film after etching, which represents wiring. However, the residue 3d of the AlCu film is generated on the SiO ₂ film 2.

Referring to FIG. 2 (g), baking was carried out for 20 minutes at 175 ° C. three times to further flow the edge of the dripping mask 5b, and the dripping resist mask 5c.
To form. After that, the surface of the AlCu film 3 is hit with oxygen plasma for 30 seconds to increase hydrophilicity.

Referring to FIG. 2H, the residue 3d of the AlCu film is removed by etching using the mask 5c as a mask. The etching liquid is, for example, a mixed liquid of phosphoric acid, acetic acid, and nitric acid, and the liquid temperature is 50 ° C. and the etching time is 15 seconds.

Referring to FIG. 2 (i), the mask 5c is removed. In this way, the wiring 3c covered with the anodic oxide film 4 and having no eaves of the anodic oxide film was formed.

3A to 3F are sectional views in order of the processes, showing the third embodiment. Below, referring to these figures,
An example will be described. Refer to FIG. 3 (a). Reference numeral 1 is a Si substrate on which element formation has been completed, on which a SiO ₂ film 2 having a thickness of, for example, 4000 Å is formed as an insulating film.
On top of that, as a conductive film, for example, AlC with a thickness of 1.1 μm
The u film 3 is deposited. The surface of the AlCu film 3 is anodized to form an anodized film 4 having a thickness of about 500Å.

Referring to FIG. 3B, a resist mask 5 for forming wiring is formed on the anodic oxide film 4. The anodic oxide film 4 is etched and removed using the resist mask 5 as a mask. The etching solution is, for example, a mixed solution of acetic acid and ammonium hydrogen fluoride.

Referring to FIG. 3 (c), baking is performed at 175 ° C. for 20 minutes, and the resist mask 5 is formed.
The edge portion of is flowed to form a sagging resist mask 5a. After that, the surface of the AlCu film 3 is hit with oxygen plasma for 30 seconds to increase hydrophilicity.

The process up to this point is the same as in the second embodiment. Referring to FIG. 3 (d), the AlCu film 3 is etched and removed using the mask 5a as a mask to form the wiring 3e. The etching liquid is, for example, a mixed liquid of phosphoric acid, acetic acid, and nitric acid, and the liquid temperature is 50 ° C.
The etching time is 145 seconds. The AlCu film 3 is removed and no residue is generated. However, the side etching progresses more than the thickness of the mask 5a, which covers the side surface of the anodic oxide film 4, so that the anodic oxide film 4 is partially exposed to form the eaves 4a.

Referring to FIG. 3E, the eaves 4a is isotropically dry-etched with CF ₄ gas to be removed. Instead of dry etching, wet etching using a mixed solution of acetic acid and ammonium hydrogen fluoride may be adopted.

Referring to FIG. 3 (f), the sagging mask 5a is peeled off. In this way, the wiring 3e covered with the anodic oxide film 4 and having no eaves of the anodic oxide film was formed.

4A to 4F are sectional views in order of the processes, showing the fourth embodiment. Below, referring to these figures,
An example will be described. See Fig. 4 (a). This figure is a reprint of Fig. 2 (c).
The description is omitted because it is the same as the embodiment described above.

Referring to FIG. 4B, the AlCu film 3 is etched using the mask 5a as a mask. 3f represents the AlCu film after etching. The etching solution is, for example, a mixed solution of phosphoric acid, acetic acid, and nitric acid, the liquid temperature is 50 ° C., and the etching time is 60 seconds. AlCu
About half of the thickness of the film 3 is etched, and a part of the anodic oxide film 4 is exposed by side etching to form the eaves 4a.

Referring to FIG. 4 (c), the eaves portion 4a is isotropically dry-etched and removed by CF ₄ gas. Instead of dry etching, wet etching using a mixed solution of acetic acid and ammonium hydrogen fluoride may be adopted.

Referring to FIG. 4 (d), baking is performed at 175 ° C. for 20 minutes to further flow the edge of the dripping mask 5a to form a dripping resist mask 5b. After that, the surface of the AlCu film 3f is hit with oxygen plasma for 30 seconds to increase hydrophilicity.

Referring to FIG. 4E, the AlCu film 3f is etched using the mask 5b as a mask. The etching liquid is, for example, a mixed liquid of phosphoric acid, acetic acid, and nitric acid, and the liquid temperature is 50 ° C. and the etching time is 75 seconds. 3g represents the wiring formed by this etching.
Before the anodic oxide film 4 is exposed by the side etching of the AlCu film, the etching for forming the wiring is completed.

Referring to FIG. 4 (f), the sagging mask 5b is peeled off. In this way, the wiring 3g covered with the anodic oxide film 4 and having no eaves of the anodic oxide film was formed.

[0046]

As described above, according to the present invention,
It is possible to prevent the eaves from forming on the anodic oxide film covering the wiring. As a result, the abnormal growth of the interlayer insulating film on the wiring is eliminated, and the coverage failure of the upper wiring is eliminated. Along with this, the yield of wafers is improved.

Further, since the eaves is not formed on the anodic oxide film, the anodic oxide film is not peeled off. As a result, the abnormal growth of the interlayer insulating film on the wiring is eliminated, and the coverage failure of the upper wiring is eliminated. Along with this, the yield of wafers is improved.

[Brief description of drawings]

1A to 1E are sectional views in order of steps, showing a first embodiment.

2A to 2I are sectional views in order of the processes, showing the second embodiment.

3A to 3F are cross-sectional views in order of the processes, showing the third embodiment.

4A to 4F are cross-sectional views in order of the processes, showing the fourth embodiment.

5A to 5E are cross-sectional views in order of the processes, showing a conventional example.

6 (a) and 6 (b) are cross-sectional views for explaining the problems of the conventional example.

[Explanation of symbols]

1 is a semiconductor substrate, Si substrate 2 is an insulating film, SiO ₂ films 3, 3b, 3f are conductive films, and AlCu films 3a, 3c, 3e, 3g are conductive films and AlCu films are wirings. 3d is a residue, the residue of the AlCu film 4 is an anodized film 4a is an eaves, the eaves of the anodized film 5 is a mask, the resist masks 5a and 5b are sloppy masks 6 is an interlayer insulating film and a PSG film 7 is an upper layer wiring and is an AlCu film

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tomoyuki Saito 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (3)

[Claims] 1. An anodized film (4) is obtained by forming a conductive film (3) on an insulating film (2) on a semiconductor substrate (1) and then anodizing the surface.
And a step of selectively etching and removing the anodic oxide film (4) using the mask (5) formed on the anodic oxide film (4) as a mask, and the mask (5) Is used as a mask to remove the conductive film (3) isotropically by etching, and then the anodic oxide film (4) exposed by side etching
And a step of removing the portion by etching, and forming a conductive film wiring (3a) whose upper surface is covered with the anodic oxide film (4). 2. An anodized film (4) is formed by forming a conductive film (3) on an insulating film (2) on a semiconductor substrate (1) and then anodizing the surface.
And a step of selectively etching and removing the anodic oxide film (4) by using the mask (5) formed on the anodic oxide film (4) as a mask, and heating the mask ( Five)
After the edge portion of the film is made to flow to form a sloping mask (5a) covering the side surface of the anodic oxide film (4), the conductive film (3) isotropic with the sloping mask (5a) as a mask. And removing the conductive film (3) without exposing the anodic oxide film (4), and the upper surface of the conductive film wiring (3c) is covered with the anodic oxide film (4). A method for manufacturing a semiconductor device, comprising: 3. An anodized film (4) is formed by forming a conductive film (3) on an insulating film (2) on a semiconductor substrate (1) and then anodizing the surface.
And a step of selectively etching and removing the anodic oxide film (4) by using the mask (5) formed on the anodic oxide film (4) as a mask, and heating the mask ( Five)
After the end portion of the film is made to flow to form a sagging mask (5a) that covers the side surface of the anodic oxide film (4), the conductive film (3) isotropic with the sagging mask (5a) as a mask. Etching and removing, and then etching and removing the portion of the anodic oxide film (4) exposed by side etching.
A method of manufacturing a semiconductor device, comprising forming a conductive film wiring (3e) having an upper surface covered with an anodic oxide film (4).