JPH118242A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device wherein the resistance of an interconnection is suppressed from rising. SOLUTION: A groove 11 is formed on an interlayer insulating film 10. A first metal film 12 is formed by a method having a directionality of embedding the groove 11, followed by isotropic etching of the first metal film 12 so as to expose the upper portion of the interlayer insulating film 10. Then, a second metal film 13 serving as a protection film made of a material harder than the first metal film 12a, is formed on the first metal film 12a and the interlayer insulating film 10. Through chemical mechanical polishing, the first metal film 12a and the second metal film 13 which are formed in a region other than the interior of the groove 11, are removed. Since the upper surface of the first metal film 12 is completely covered with the second metal film 13, i.e., the protective film, a semiconductor device can be formed without reducing the effective area of the first metal film 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a protective film for preventing a buried wiring from being corroded and increasing the resistance of the wiring.

[0002]

FIG. 3 shows, for example, June 9-10 and 199.
FIG. 2 is a cross-sectional view showing a method for manufacturing a conventional semiconductor device shown in 2 VMIC Conference. A conventional method for manufacturing a semiconductor device will be described with reference to the drawings. First, a trench 2 for forming a wiring is formed in the first interlayer insulating film 1 by photolithography and dry etching. Next, a metal film 3 made of an aluminum alloy film or a copper alloy film is deposited by using a collimation sputtering method. Next, a barrier layer 4 made of a titanium nitride film is deposited by a sputtering method (FIG. 3A).

Next, a protective film 5 made of a tungsten film is deposited by chemical vapor deposition (CVD method) (FIG. 3).
(B)). Next, the protective film 5, the barrier layer 4, and the metal film 3 formed outside the groove 2 are removed by chemical mechanical polishing. Then, the metal film 3a formed in the groove 2,
The wiring 6 composed of the barrier layer 4a and the protection film 5a is formed (FIG. 3C).

Next, TEO is used as a raw material on the wiring 5 and the first interlayer insulating film 1 by using, for example, a plasma CVD method.
Using S and O ₂ , as a lamination condition, a temperature of 300 to
At 400 ° C., a second interlayer insulating film 8 made of a silicon oxide film is formed (FIG. 3D). Then, although not shown, in a later step, for example, a connection hole, an upper wiring, and the like are formed in the upper layer.

[0005]

The conventional method of manufacturing a semiconductor device is performed as described above, and the metal film 3 is generally formed of an aluminum alloy film or a copper alloy film in order to reduce the resistance of the wiring. Are used. Since these materials are soft in material, if chemical mechanical polishing is directly performed, scratches (damages) are likely to be formed on the upper surface of the metal film 3. Therefore,
In order to protect the soft metal film 3, a film made of a material harder than the metal film 3 is formed on the metal film 3 as the protection film 4.

However, when the width of the wiring is reduced and the aspect ratio of the groove 2 is increased, such as a logic device having a rule of 0.18 μm or less and a DRAM of 1 Gbit or less,
The thickness of the metal film 3 for filling the groove 2 is increased,
The metal film 3 is also laminated on the upper side wall of the metal film 3.
Therefore, the protective film 4 is not formed on the upper sidewall of the groove 2, and
Part of the metal film 3a is directly exposed to chemical mechanical polishing. Then, the soft metal film 3a is scratched.
Then, a chemical solution (abrasive, called a slurry) at the time of chemical mechanical polishing penetrates into the scratch.
There is a possibility that the eroded portion 7 as shown in FIG.

When the metal film 3 is formed of a Cu film, the Cu film is easily oxidized in an oxidizing atmosphere at 150 ° C. or higher. At the time of formation, the metal film 3a exposed above the trench 2 is easily oxidized, and the oxidized region 9 may be formed. Also, in the step of opening the connection hole formed on the other wiring 6, the above-described phenomenon occurs, and the same as in the formation of the second interlayer insulating film 8, The exposed metal film 3a may be oxidized, and an oxidized region 9 may be formed.

The eroded portion 7 or the oxidized region 9 reduces the cross-sectional area of the wiring 6, and the effective cross-sectional area of the wiring 6 is reduced by the reduced amount, and the resistance of the wiring 6 increases. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a method of manufacturing a semiconductor device in which the resistance of a wiring does not increase.

[0010]

Means for Solving the Problems Claim 1 according to the present invention.
Forming a groove in an interlayer insulating film;
Forming a first metal film by a method having directivity so as to fill the groove, isotropically etching the first metal film, exposing an interlayer insulating film above the groove, and forming a first metal film on the first metal film; A protective film made of a material harder than the first metal film is formed on the interlayer insulating film. Then, the first metal film and the protective film formed in a region other than the inside of the groove are removed by chemical mechanical polishing.

According to a second aspect of the present invention, in the method for manufacturing a semiconductor device, a groove is formed in the interlayer insulating film, and the first metal film is formed by a method having directivity so as to fill the groove. The first metal film is isotropically etched to expose the interlayer insulating film above the groove, and a protective film having selectivity with the first metal film is formed on the first metal film and the interlayer insulating film. I do. Then, the first metal film formed on the interlayer insulating film is removed by chemical-mechanical polishing to remove the protective film formed in a region other than the inside of the groove.

In a third aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the first metal film is made of an aluminum alloy or a copper alloy.

According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to third aspects, the protective film is formed of a second metal film.

According to a fifth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to third aspects, the protective film is made of an insulating film.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a method for manufacturing a semiconductor device according to the first embodiment of the present invention. A method for manufacturing the semiconductor device according to the first embodiment will be described with reference to the drawings. First, a groove 11 having a size of, for example, 300 nm in width and 400 nm in depth for wiring formation is formed in the interlayer insulating film 10 by photolithography and dry etching.

Next, as a method having directivity, for example, an ionization sputtering method as a physical vapor deposition method, a collimation sputtering method, a long distance sputtering method, a self-discharge sputtering method, a vacuum vapor deposition method, a cluster ion beam method, or the like is used. For example, a first metal film 12 made of, for example, a copper alloy film is deposited to a thickness of, for example, 450 nm.

At this time, since the first metal film 12 is formed by a method having directivity, the film thickness formed at the bottom of the groove 11 is larger than that formed at the side wall of the groove 1. The concave portions of the first metal film 12 are stacked in a shape slightly smaller than the width of the groove 11. In this case, the thickness of the first metal film 12 from the bottom of the groove 11 is approximately 400 nm, while the thickness from the side wall of the groove 11 is 50 nm or less (FIG. 1A).

Next, the first metal film 12 is isotropically etched until the interlayer insulating film 10 above the trench 11 is exposed. As a method, for example, wet etching is performed using a solution of prepionic acid and hydrogen peroxide, and the etching rate is about 16.7 nm / min, so that the etching may be performed for about 3 minutes (FIG. 1B).

Next, a second metal film 13 as a protective film made of a tungsten film made of a material harder than the first metal film 12 is deposited to a thickness of, for example, 100 nm by using, for example, an ionization sputtering method. FIG. 1 (c)). Next, the second metal film 13 and the first metal film 12a formed outside the groove 11 are removed by chemical mechanical polishing.

At this time, the second groove formed above the groove 11
Is slightly etched, and the second metal film 13a having a thickness of about 50 nm remains. And groove 1
1, a first metal film 12b and a second metal film 12b.
The wiring 14 made of the metal film 13a is formed. At this time, the upper surface of the first metal film 12b is completely covered with the second metal film 13
a (FIG. 1D).

Next, although not shown, for example, wiring 1
4 and the interlayer insulating film 10 are formed by using, for example, a plasma CVD method, using TEOS and O ₂ as raw materials, setting the temperature to 300 to 400 ° C. as a laminating condition, and forming an upper interlayer insulating film made of a silicon oxide film. In addition, for example, a connection hole, an upper wiring, and the like are formed in the upper layer.

According to the method of manufacturing the semiconductor device of the first embodiment performed as described above, since the upper surface of the first metal film 12b is completely covered with the second metal film 13, The second metal film 13, which is hard in material during polishing, is not scratched, and the first metal film 12 b is not directly exposed to an oxidizing atmosphere in a process after the formation of the wiring 14. Therefore, the first metal film 12b is not oxidized. Therefore, the effective cross-sectional area of the wiring 14 does not decrease, and an increase in the resistance of the wiring 14 can be prevented.

As the second metal film 13, any material having a material harder than the first metal film 12 may be used. For example, a titanium nitride film may be used as a method having directivity other than the method described above. However, it is needless to say that the same effect as that of the first embodiment can be obtained even if the film is deposited by, for example, a CVD method using high-density plasma and then formed in the same manner.

Embodiment 2 FIG. In the first embodiment, the example in which the protection film made of a material harder than the first metal film 12 is formed by the second metal film 13 has been described. However, the present invention is not limited thereto. A protective film made of a material harder than a metal film may be formed of an insulating film. In this case, the second metal film 1 described in the first embodiment is used.
Instead of 3, an insulating film such as a silicon oxide film or a silicon nitride film may be deposited by a plasma CVD method or a high-density plasma CVD method and formed in the same manner as in the first embodiment.

According to the second embodiment performed as described above, the insulating film itself as the protective film cannot be used as a part of the wiring, but the first metal is formed similarly to the first embodiment. It can be formed by completely covering the upper surface of the film with an insulating film. Further, since the insulating film is amorphous, the protective action against chemicals and oxidation is further enhanced as compared with a polycrystalline metal film. Therefore, the effective cross-sectional area of the wiring does not decrease, and an increase in the resistance of the wiring can be reliably prevented.

In each of the above embodiments, an example is shown in which the first metal film is formed of a copper alloy film. However, the present invention is not limited to this. If it is formed of, for example, an aluminum alloy film, the same effects as the above embodiments can be obtained.

Embodiment 3 FIG. 2 is a cross-sectional view showing a method for manufacturing a semiconductor device according to Embodiment 3 of the present invention. A method for manufacturing the semiconductor device according to the third embodiment will be described with reference to the drawings. First, similar to the above embodiments,
For example, a width of 300 nm and a depth of 400 for wiring formation is formed on the interlayer insulating film 10 by photolithography and dry etching.
A groove 11 having a size of nm is formed.

Next, as a method having directivity, for example, an ionization sputtering method, a collimation sputtering method, a long-distance sputtering method, a self-discharge sputtering method, a vacuum evaporation method, and a cluster ion beam method as physical vapor deposition methods are used. For example, a first metal film 12 made of, for example, a copper alloy film is deposited to a thickness of, for example, 450 nm.

At this time, since the first metal film 12 is formed by a method having directivity, the film thickness formed at the bottom of the groove 11 is larger than that formed on the side wall of the groove 11. The concave portions of the first metal film 12 are stacked in a shape slightly smaller than the width of the groove 11. In this case, the thickness of the first metal film 12 from the bottom of the groove 11 is approximately 400 nm, while the thickness from the side wall of the groove 11 is 50 nm or less.

Next, the first metal film 12 is isotropically etched until the interlayer insulating film 10 above the trench 11 is exposed. As a method, for example, wet etching is performed using a solution of prepionic acid and hydrogen peroxide, and the etching rate is about 16.7 nm / min. Therefore, the etching may be performed for about 3 minutes (FIG. 2A).

Next, a second metal film 15 as a protective film composed of a tungsten film having selectivity with the first metal film 12 is formed, for example, by using an ionization sputtering method.
A thickness of 00 nm is deposited (FIG. 2B). Next, the second metal film 15 formed outside the groove 11 is removed by chemical mechanical polishing (FIG. 2C). At this time, the second metal film 15 in the groove 11 is hardly subjected to the chemical stress of the chemical mechanical polishing, so that the thickness of the second metal film 15 in the groove 11 is not reduced.

Next, the first metal film 12a made of a copper alloy film is immersed in, for example, an amine solution to remove the first metal film 12a. At this time, since the second metal film 15a is formed of a tungsten film, it is hardly etched by the amine-based solution. Thus, the first metal film 12a covered with the second metal film 15a is not removed. Therefore, the groove 11
The first metal film 12a formed therein and covered by the second metal film 15a remains.

Next, the second metal film 15a on the side wall is removed by chemical mechanical polishing. At this time, the second metal film 15a formed above the groove 11 is also slightly etched, so that the second metal film 15b having a thickness of about 50 nm remains. Then, the first metal film 12c and the second metal film 1
The wiring 16 made of 5b is formed (FIG. 2D).

Next, although not shown, for example, wiring 1
6 and the interlayer insulating film 10 are formed by using, for example, a plasma CVD method, using TEOS and O ₂ as raw materials, setting the temperature to 300 to 400 ° C. as a laminating condition, and forming an upper interlayer insulating film made of a silicon oxide film. In addition, for example, a connection hole, an upper wiring, and the like are formed in the upper layer.

The removal of the side wall of the second metal film 15a is performed as follows.
Although an example in which chemical mechanical polishing is performed has been described, even if this method is omitted, it is easily removed by mechanical stress such as an ultrasonic cleaning process in a cleaning process performed during a normal process. Can do things.

According to the method of manufacturing the semiconductor device of the third embodiment performed as described above, the upper surface of the first metal film 12b formed in the trench 11 is completely formed by the second metal film 15. Since the second metal film 15 is not etched when the first metal film 12a is etched,
The first metal film 12a in 1 can be reliably left.

Further, in the step after the formation of the wiring 16, the first metal film 12c is not directly exposed to the oxidizing atmosphere, so that the first metal film 12c is not oxidized. Therefore, the effective cross-sectional area of the wiring 16 does not decrease, and an increase in the resistance of the wiring 16 can be prevented.

The second metal film 15 may have any selectivity with respect to the first metal film 12. For example, a titanium nitride film may be used as a method having directivity other than the method described above. For example, CV using high density plasma
It is needless to say that the same effect as in the third embodiment can be obtained by depositing by the method D and forming the same in the following.

In the third embodiment, the first metal film 1
Although an example of forming the layer 2 with a copper alloy film has been described, the present invention is not limited to this, and any material having a small resistance that can be used for wiring may be used. Is also good.

When the first metal film 12 is formed of an aluminum alloy film and the second metal film 15 is formed of a tungsten film, the first metal film 12 is selectively etched by, for example, phosphoric acid. In the third embodiment,
The same effect as described above can be obtained.

Embodiment 4 FIG. In the third embodiment, the example in which the first metal film 12 and the protective film having the selectivity are formed by the second metal film 15 has been described. However, the present invention is not limited to this. A protective film having selectivity with the metal film may be formed using an insulating film. In this case, instead of the second metal film 15 shown in the third embodiment, an insulating film such as a silicon oxide film or a silicon nitride film is formed by plasma CDV or high-density plasma C.
What is necessary is just to deposit by a DV method and to form like Embodiment 3 above.

According to the fourth embodiment performed as described above, the insulating film itself as the protective film cannot be used as a part of the wiring, but the first metal is formed similarly to the third embodiment. It can be formed by completely covering the upper surface of the film with an insulating film. Further, since the insulating film is amorphous, the protective action against chemicals and oxidation is further enhanced as compared with a polycrystalline metal film. Therefore, the effective cross-sectional area of the wiring does not decrease, and an increase in the resistance of the wiring can be reliably prevented.

Each of the above-described embodiments is described as a .0.
If it is used for a semiconductor device such as a logic device with a rule of 18 μm or less, a DRAM of 1 Gbit or more, and a wiring having a finer wiring width and a larger groove aspect ratio,
It will be more effective.

[0044]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a groove in an interlayer insulating film; and forming a first metal film by a method having directivity so as to fill the groove. The first metal film is isotropically etched to expose the interlayer insulating film above the trench, and on the first metal film and the interlayer insulating film,
A protective film made of a material harder than the first metal film is formed.
Then, the first metal film and the protective film formed in the region other than the inside of the groove are removed by chemical mechanical polishing, so that the first metal film is not exposed to the outside and Since the semiconductor device is covered with the protective film, there is an effect that a method for manufacturing a semiconductor device in which the effective area of the first metal film does not decrease can be provided.

According to a second aspect of the present invention, in the method of manufacturing a semiconductor device, a groove is formed in the interlayer insulating film, and the first metal film is formed by a method having directivity so as to fill the groove. The first metal film is isotropically etched to expose the interlayer insulating film above the groove, and a protective film having selectivity with the first metal film is formed on the first metal film and the interlayer insulating film. I do. Then, the first metal film formed on the interlayer insulating film is removed by chemical mechanical polishing to remove the protection film formed in the region other than the inside of the groove, so that the first metal film is exposed to the outside. Since the first metal film is covered with the protective film without performing the method, there is an effect that it is possible to provide a method for manufacturing a semiconductor device without reducing the effective area of the first metal film.

According to a third aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the first metal film is made of an aluminum alloy or a copper alloy.
There is an effect that it is possible to provide a method for manufacturing a semiconductor device in which the resistance of the first metal film can be reduced.

According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to third aspects, the protective film is formed of the second metal film. There is an effect that a method for manufacturing a semiconductor device in which a film can be used as a wiring can be provided.

According to a fifth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to third aspects, since the protective film is made of an insulating film, the first metal film is surely formed. There is an effect that it is possible to provide a method of manufacturing a semiconductor device capable of protecting the semiconductor device.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a method for manufacturing a semiconductor device according to a first embodiment of the present invention;

FIG. 2 is a sectional view illustrating a method for manufacturing a semiconductor device according to a third embodiment of the present invention;

FIG. 3 is a cross-sectional view showing a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

10 interlayer insulating film, 11 groove, 12, 12a, 12b, 12c first metal film, 13, 13a, 15, 15a, 15b second metal film,
14,16 wiring.

Claims (5)

[Claims] A step of forming a groove in the interlayer insulating film, a step of forming a first metal film by a method having directivity so as to fill the groove, and forming the first metal film in an isotropic manner. Etching to expose the interlayer insulating film above the trench; and forming the interlayer insulating film on the first metal film and the interlayer insulating film.
A step of forming a protective film made of a material harder than the first metal film, and a step of removing the first metal film and the protective film formed in a region other than the inside of the groove by chemical mechanical polishing And a method for manufacturing a semiconductor device. 2. A step of forming a groove in an interlayer insulating film, a step of forming a first metal film by a directional method so as to fill the groove, and forming the first metal film in an isotropic manner. Etching to expose the interlayer insulating film above the trench; and forming the interlayer insulating film on the first metal film and the interlayer insulating film.
A step of forming a protective film having selectivity with the first metal film, a step of removing the protective film formed in a region other than the inside of the groove by chemical mechanical polishing, and a step of removing the protective film on the interlayer insulating film. Removing the formed first metal film. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the first metal film is made of an aluminum alloy or a copper alloy. 4. The method for manufacturing a semiconductor device according to claim 1, wherein the protective film is formed of a second metal film. 5. The method for manufacturing a semiconductor device according to claim 1, wherein the protective film is made of an insulating film.