JPH104139A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device manufacturing method capable of forming wirings in recessions without spoiling the reliability. SOLUTION: An interlayer insulating film 19 having a contact hole 20 is overlaid with a first metal film 22 of Al containing impurities. And by heating the first metal film 22, a first metal film 22a is buried in the contact hole 20. The first metal film 22a is overlaid with a second metal film 23 composed of an Al film. The first and second metal films 22a, 23 are heated to diffuse impurities, and the impurity concentrations of the first and second metal films 22a, 23a are made equal to make a third metal film 24.

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 for forming a wiring in a fine recess having a large aspect ratio without deteriorating reliability.

[0002]

2. Description of the Related Art As LSIs have become more highly integrated, demands for miniaturization of multilayer wiring have become more and more severe. While the width of the wiring and the scale of the connection hole are reduced, the thickness of the interlayer insulating film between the upper and lower wirings is not reduced because it is necessary to prevent an increase in the capacitance between the wirings. Therefore, the aspect ratio of the connection hole (the ratio of the depth to the diameter of the connection hole) increases to about 2 to 3. When a metal such as an aluminum wiring is formed in such a connection hole having a high aspect ratio, the thickness of the connection hole side wall becomes extremely thin, so that the wiring is disconnected and the reliability is significantly deteriorated. Therefore, a high-temperature sputtering method and a reflow method have been proposed as a method of embedding the aluminum wiring in the connection hole.

[0003] For example, as shown in FIG.
A barrier metal film 4 made of, for example, TiN is formed in a contact hole 3 as a recess formed in the interlayer insulating film 2 laminated thereon, and an Al alloy film 5 containing, for example, 0.5% of Cu is formed by a sputtering method. In this method, the Al alloy film 5 is flowed (reflowed) at a temperature of 400 to 500 ° C. and buried in the contact hole 3 as shown in FIG. However, since this temperature is lower than the melting point of 660 ° C. of the Al alloy film 5, sufficient fluidity of the Al alloy film 5 cannot be obtained, and the contact hole 3 having an aspect ratio of about 2 to 3 is completely buried. Difficult to do, void 6
Are often formed. Therefore, there is a problem that the reliability of the product is reduced.

Further, the heating temperature is set to about 600 ° C.
There is also a method in which the difference from the melting point of the alloy film 5 is set to several tens of degrees Celsius to improve the fluidity, and the contact hole 3 is buried. However, when heated at such a temperature, the SOG is applied to the interlayer insulating film 2.
When a film is used, cracks may occur in the interlayer insulating film 2, which may cause a problem such as deterioration of moisture resistance of the interlayer insulating film 2. Further, when flowing into the contact hole 3 formed on the surface of the semiconductor substrate 1 at 600 ° C., the barrier property of the barrier metal film 4 is not normally secured up to 600 ° C., so that Al in the Al alloy film 5 and Si in the semiconductor substrate 1 There is a problem that mutual diffusion with Ti cannot be prevented (TiN
The barrier property of preventing mutual diffusion between Al and Si is up to about 550 ° C. ).

As a method of solving such a problem and reliably filling an aluminum alloy film in a contact hole having a large aspect ratio, a technique disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 4-23319 has been proposed. First, as shown in FIG. 10, an interlayer insulating film 8 is laminated on a semiconductor substrate 7, and a contact hole 9 is formed in a predetermined region. Next, the Al alloy film 10 is made of an alloy of Al and Ge by a sputtering method. In this case, the Ge concentration is set to, for example, 20%, and the effective wafer temperature during sputtering is set to the melting point of Al-20% Ge. There 420
Laminate by heating to around ℃. Therefore, the Al alloy film 10 is reliably embedded in the contact hole 9.

As described above, a technique has been proposed in which an impurity is mixed into aluminum to lower the melting point and thereby bury the aluminum in a contact hole. When this technique is applied to a multilayer wiring, as shown in FIG.
When the upper Al alloy film 11 made of% Ge is formed at a high temperature, the lower Al alloy film 10 made of Al-20% Ge dissolves. At this time, the lower Al alloy film 10 and the interlayer insulating film 1
2, a stress is applied to the lower Al alloy film 10. Therefore, for example, corners where this stress is concentrated,
For example, stress imbalance occurs at portions where the thickness of the interlayer insulating film 12 is different, for example, at contact holes or wirings, and the portions 13 are extruded by the molten lower Al alloy film 10 at these portions. And this extruded part 1
3 may unnecessarily come into contact 14 with each other, which may cause a short circuit between wirings or a hillock.

As a technique for solving such a problem,
For example, JP-A-6-151607 has been proposed. As shown in FIG. 12, a lower Al alloy film 16 made of, for example, Al-25% Ge is formed via a barrier metal 15, and an upper Al alloy film 17 made of, for example, Al-5% Ge is formed.
Is formed via the barrier metal 15 and the upper layer and the lower layer A are formed.
A method is shown in which the melting points of the l-alloy films 16 and 17 are lowered so as to reach the upper wiring.

[0008]

The conventional semiconductor device is configured as described above. When a contact hole having a large aspect ratio is buried, an impurity which lowers the melting point of Al is added to Al and the fluidity of the Al alloy film is increased. Was responded to by raising However, if an amount of impurities necessary for obtaining the fluidity for filling the contact hole is added to Al, there is a problem that the resistance of the wiring itself increases and the electrical characteristics deteriorate.

In the case where the wiring is used for a multilayer wiring, the above problem is remarkable because the problem is dealt with by increasing the impurity concentration toward the upper layer. Further, in the case of a multilayer wiring, although the impurity concentration is increased and the melting point is lowered toward the upper layer, the lowering of the melting point due to the addition of the impurity is limited, so that it is not applicable to the wiring of three or more layers. There was a problem that it was extremely difficult.

[0010] Actually, post-wiring processes used up to now include a high-temperature process such as a baking process at 400 to 450 ° C. Such a process cannot be used for general purposes, or if it is performed conventionally, the problem shown in FIG. 11 occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a method of manufacturing a semiconductor device in which a wiring can be formed in a concave portion without impairing reliability.

[0012]

Means for Solving the Problems Claim 1 according to the present invention.
In the method of manufacturing a semiconductor device, a first metal film containing an element having a eutectic reaction with Al is stacked on an interlayer insulating film having a concave portion, and the first metal film is heated to form a concave portion. A first metal film is buried in the second metal film, and on the first metal film, Al contains an element having a concentration lower than that of the element contained in the first metal film, or a second element not containing Al Are stacked, and the first and second metal films are heated to diffuse the elements,
The same concentration of the elements in the first and second metal films is set and the third
Metal film.

According to a second aspect of the present invention, in the method for manufacturing a semiconductor device according to the first aspect, the lamination of the first metal film is performed while heating, so that the lamination of the first metal film is performed into the concave portion of the first metal film. Embedded at the same time.

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 lamination of the second metal film is performed while heating the first and second metal films. The elements in the metal film are simultaneously diffused to make the concentrations of the elements in the second and first metal films the same to form a third metal film.

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, after the first metal film is embedded in the recess, the first metal film is formed outside the recess. The removed first metal film is removed.

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 fourth aspects, the thickness of the third metal film is reduced by etching.

According to a sixth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to fifth aspects, a barrier metal film is formed between the first metal film and the interlayer insulating film. Is what you do.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a semiconductor device according to any one of the first to sixth aspects, wherein the element having a eutectic reaction with Al is Cu or
Ge, Mg, or Ga is used.

According to an eighth aspect of the present invention, there is provided a method of manufacturing a semiconductor device according to any one of the first to seventh aspects, wherein the method of manufacturing a semiconductor device is formed on a lower wiring layer and a lower wiring layer. When used for a multilayer wiring having an upper wiring layer, the concentration of the element in the upper first metal film is higher than the concentration of the element in the lower third metal film.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, an embodiment 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, an interlayer insulating film 19 is formed by laminating a silicon oxide film to a thickness of 1 μm on a semiconductor substrate 18 using, for example, a CVD method. Next, a contact hole 20 as a concave portion is formed at a desired position, for example, with a diameter of 0.5 μm (therefore, the aspect ratio of the contact hole 20 is 2). Next, the thickness 2 is formed using, for example, a sputtering method or a CVD method.
A barrier metal film 21 is formed by sequentially laminating a 0 nm Ti film and a 100 nm thick TiN film.

Next, a first metal film 22 containing, for example, Cu (hereinafter, referred to as an impurity) as an element having a eutectic reaction with Al at 6% (all the percentages indicate weight%). Are stacked by, for example, a sputtering method to a thickness of 200 nm (FIG. 1A). At this time, it is clear from the state diagram of Al-Cu shown in FIG. 8 that Cu has a eutectic reaction with Al. From this figure, it can be confirmed that the first metal film 22 has a liquid phase at 548 ° C. Next, the first metal film 22 is heated to, for example, 400 to 500 ° C. and made to flow, and the first metal film 22
Is embedded (FIG. 1B). At this time, the first metal film 22
Since the temperature (and melting point) at which a liquid phase appears is reduced by containing 6% of impurities, the fluid can be flowed at a lower temperature than in the conventional case, and the contact hole can be surely heated to 400 to 500 ° C. 20 can be embedded.

Next, an Al film having a thickness of 400 nm is laminated on the first metal film 22a by, for example, a sputtering method to form a second metal film 23 (FIG. 1C). Next, the first and second metal films 22a and 23 are heated at, for example, 400 ° C. for several minutes (for example, about 30 minutes) to diffuse impurities in the first metal film 22a into the two metal films 22a and 23. The third metal film 24 is formed by making the concentration of impurities in both metal films 22a and 23 uniform. At this time, the impurity concentration of the third metal film 24 becomes about 1/3 of the first metal film 22a, that is, 2% (this is determined by the volume ratio of the first and second metal films 22a and 23). (FIG. 1D). Next, the third metal film 24 and the barrier metal film 2 are formed by photolithography.
1 to form a wiring 25 (FIG. 1)
(E)).

According to the method of manufacturing the semiconductor device of the first embodiment performed as described above, the first metal film 22 having a temperature at which the liquid phase appears at 548 ° C. is used. 22 is made to flow at a low heating of 400 to 500 ° C., so that it can be reliably embedded in the contact hole 20. Also, the third wiring finally formed as the wiring 25
Of the first metal film 22 to the second metal film 23
a, and the first and second metal films 22 are diffused.
It is formed by making the concentration of impurities in a and 23 uniform. Therefore, the impurity concentration in the third metal film 24 is about 2%, and the temperature at which the liquid phase appears is about 620 ° C., so that there is no deformation due to the heat treatment in the subsequent step. Further, since the impurity concentration of the wiring 25 is lower than that of the first metal film 22, an increase in the resistance of the wiring 25 can be minimized.

In the first embodiment, the first and second metal films 22a and 23 are heated to form the third metal film 24 having a uniform impurity concentration, and thereafter, the wiring is formed by patterning. However, the present invention is not limited to this. For example, after forming as shown in FIG. 1C through the same process as in the first embodiment, as shown in FIG. , 23 and the barrier metal film 21 are patterned (FIG. 2A). Thereafter, the first and second metal films 22a and 23 are heated to 400 to 500 ° C. to diffuse impurities and to form the two metal films 22a and 23a. The same effect as described above can be obtained by forming the third metal film 26 by making the impurity concentration in the metal layer 23 uniform, and forming the wiring 27 composed of the barrier metal film 21 and the third metal film 26.

Embodiment 2 FIG. 3 is a sectional view showing the method for manufacturing the semiconductor device according to the second embodiment of the present invention. FIG.
A method of manufacturing the semiconductor device according to the second embodiment will be described with reference to FIG. First, through the same steps as in the first embodiment, as shown in FIG.
a is buried in the contact hole 20. Next, the first metal film 22a formed outside the contact hole 20
And the barrier metal 21 is, for example, etched back or
The first metal film 22b and the barrier metal 21a after the removal are removed only in the contact hole 20 by polishing (FIG. 3A).

Next, an Al film is formed on the interlayer insulating film 19 and the first metal film
m to form a second metal film 28 (FIG. 3
(B)). Next, the first and second metal films 22b and 28
Is heated, for example, at 400 ° C. for several minutes to diffuse the impurities in the first metal film 22b into the two metal films 22b and 28, to make the impurity concentrations in the two metal films 22b and 28 uniform, and to make the third metal The film 29 is formed (FIG. 3D). Next, the wiring 30 is formed by patterning the third metal film 29 by photolithography (FIG. 3D).

According to the method of manufacturing the semiconductor device of the second embodiment performed as described above, the contact hole 20 can be surely buried similarly to the first embodiment. Since the first metal film 22b is left only in the contact hole 20, the total amount of impurities remaining when diffusing the impurities is reduced as compared with the first embodiment. The concentration of the impurity can be further reduced (however, it is desirable that the concentration of Cu as an impurity be about 0.5% in order to improve the electromigration resistance of the Al wiring). Also, the contact hole 20
In order to remove the first metal film 21a other than the inside, the third metal film 29 is reliably flattened and formed.

Embodiment 3 FIG. 4 is a sectional view showing a method for manufacturing a semiconductor device according to the third embodiment of the present invention. FIG.
A method of manufacturing the semiconductor device according to the third embodiment will be described with reference to FIGS. First, through the same steps as in the first embodiment, the first metal film 22a is formed as shown in FIG.
Is embedded in the contact hole 20. Next, an Al film is laminated on the first metal film 22a by using, for example, a sputtering method to form a second metal film 31 (FIG. 4A).

Next, the first and second metal films 22a,
1 is heated, for example, at 400 ° C. for several minutes (for example, about 3 minutes) to remove impurities in the first metal film 22a from both metal films 22a,
The third metal film 32 is diffused into the third metal film 32 to make the concentration of impurities in both metal films 22a and 31 uniform.
(B)). Next, the third metal film 32 is etched by, for example, etch-back or polishing to form a thin third metal film 32a (FIG. 4C). Next, the third metal film 32a and the barrier metal 21 are patterned by photolithography to form a wiring 33 (FIG. 4D).

According to the method of manufacturing the semiconductor device of the third embodiment performed as described above, the inside of the contact hole 20 can be surely buried similarly to the first embodiment. In order to set the impurity concentration in the third metal film 32a to a desired value,
This is addressed by setting the thickness of the metal film 31 thicker,
As a result, the thickness of the second metal film 31 is increased, and thus the thickness of the third metal film 32 is increased. However, finally, the third metal film 32 is etched to make the film thickness necessary for wiring. Since the thickness is reduced to the thickness, the wiring 33 can be formed without affecting other portions.

Therefore, the wiring 33 can be set to a desired impurity concentration without affecting other portions, and therefore, there is no deformation to the heat treatment in a later step of the wiring 33.
Further, an increase in the resistance of the wiring 33 can be minimized.

Embodiment 4 FIG. In each of the above embodiments, Al
After laminating a first metal film containing impurities, the first metal film is buried in the contact hole by a heat process,
In addition, although an example has been shown in which an impurity is diffused into the first and second metal films by a heating process after the second metal film is laminated, the present invention is not limited to this, and the first and second metal films are not limited thereto. The above-described phenomenon may be performed simultaneously by performing the film stacking while heating. Hereinafter, a fourth embodiment of this will be described with reference to FIG.

First, a contact hole 20 is formed in the interlayer insulating film 19 through the same steps as in the first embodiment, and a barrier metal film 21 is laminated. Next, 6% Cu in Al
The first metal film 34 comprising, for example, 400-500 ° C.
The layer is stacked to a thickness of 200 nm by using the sputtering method under the heating condition of At this time, since the first metal film 34 is laminated while being heated, it is formed while filling the contact hole 20 (FIG. 5A).

Next, on the first metal film 34, for example, 300
An Al film is laminated to a thickness of 400 nm by a sputtering method under a heating condition of about 500 ° C., and a second metal film is laminated. At this time, since the second metal film is laminated while being heated, impurities in the first metal film 34 are removed by the first and second metal films 3.
4 and finally a third metal film 35 having a uniform impurity concentration is formed.
(B)). Next, the third metal film 35 and the barrier metal film 21 are patterned by photolithography to form a wiring 36 (FIG. 5C).

According to the semiconductor device manufacturing method of the fourth embodiment performed as described above, the first metal film 34 is buried in the contact hole 20 simultaneously with the lamination of the first metal film 34. In addition, the number of steps is reduced because the diffusion of impurities in the first metal film 34 into the second metal film is performed simultaneously with the lamination of the second metal film and the formation of the third metal film 35 is performed simultaneously. can do. In the fourth embodiment,
The first embodiment has been described for the sake of convenience, but it is needless to say that the present invention is not limited to this and can be applied to other embodiments.

Embodiment 5 In each of the above embodiments, the contact hole 2 as a recess formed in the interlayer insulating film 19 is formed.
Although 0 has been described as an example, the present invention is not limited to this, and it is needless to say that the same can be applied to any concave portion formed in the interlayer insulating film. Hereinafter, another example of the concave portion will be described with reference to FIG.

First, a silicon oxide film is laminated on the semiconductor substrate 37 by using, for example, the CVD method, and an interlayer insulating film 38 is formed. Next, a wiring groove 39 as a concave portion is formed at a desired position, for example, with a depth of 1 μm and a width of 0.3 μm. Next, the barrier metal film 40 is formed by using, for example, a sputtering method or a CVD method. Next, Cu as an impurity is added to Al
6 is laminated (FIG. 6).
(A)).

Next, the first metal film 41 is, for example,
The first metal film 41a after the flow is buried in the wiring groove 39 by heating to 500 ° C. and flowing (FIG. 6B). Next, an Al film having a thickness of 400 nm is laminated on the first metal film 41a by using, for example, a sputtering method to form a second metal film 42 (FIG. 6C). Next, the first and second metal films 41
a, 42 are heated at 400 ° C. for several minutes (for example, about 3 minutes) to remove impurities in the first metal film 41 a from both metal films 41.
The third metal film 43 is diffused into the first and second metal films 41a and 42 to make the concentration of impurities uniform. At this time, the impurity concentration of the third metal film 24 is
This is about 2/3 of 1/3 of 1a (FIG. 6D). next,
For example, the third metal film 43 and the barrier metal film 40 other than in the wiring groove 39 are removed by using etch back or polishing to form the wiring 45 (FIG. 6E).

According to the method of manufacturing a semiconductor device of the fifth embodiment performed as described above, the first metal film 41 whose liquid phase appears at a temperature of 548 ° C. is used as in the first embodiment. Using the first metal film 22 at 400 to 500 ° C.
The wiring groove 3
9 can be reliably embedded. In addition, the third metal film 43 that finally becomes the wiring 45 diffuses the impurity of the first metal film 41a into the second metal film 42, and the first and second
Are formed by making the concentration of impurities in the metal films 41a and 42 uniform. Therefore, the concentration of the impurity in the third metal film 43 is about 2%, and the temperature at which the liquid phase appears is about 620 ° C., so there is no deformation due to the heat treatment in the subsequent step. Further, since the concentration of the impurity in the wiring 45 is lower than that in the first metal film 41, an increase in the resistance of the wiring 45 can be minimized.

Embodiment 6 FIG. In each of the above embodiments, the case where the wiring has only one layer has been described. However, it is needless to say that the same can be used for a multilayer wiring. If the method of each of the above embodiments is also applied to the multilayer wiring, the impurity concentration does not need to be higher in the upper layer, and it is possible to sufficiently cope with the case of forming three or more layers. Hereinafter, a two-layer wiring as a multilayer wiring will be described based on the first embodiment.

First, through the same steps as in the first embodiment, as shown in FIG.
To form Next, a silicon oxide film having a thickness of 1 μm is laminated on the lower wiring 25 by using, for example, a CVD method to form an upper interlayer insulating film 46. Next, an upper contact hole 47 as a concave portion is formed at a desired position, for example, with a diameter of 0.5 μm (therefore, the aspect ratio of the upper contact hole 47 becomes 2). Next, a 20-nm-thick Ti film and a 100-nm-thick TiN film are sequentially laminated by, for example, a sputtering method or a CVD method to form an upper barrier metal film 48.

Next, a 200 nm-thick upper metal film 49 is formed by sputtering, for example, in which Al as an impurity contains, for example, Cu as an impurity at a concentration of 6% higher than the impurity concentration in the lower wiring 25 (FIG. 4). 7 (a)). Next, the upper first metal film 49 is heated to, for example, 400 to 500 ° C. and caused to flow to bury the upper first metal film 49 a after flowing into the upper contact hole 47 (FIG. 7B). . At this time, since the impurity concentration of the upper first metal film 49 is higher than the impurity concentration of the lower wiring 25, a phenomenon occurs in which the lower wiring 25 flows when the upper first metal film 49 flows. Absent.

Next, an Al film having a thickness of 400 nm is laminated on the upper first metal film 49a by, for example, a sputtering method to form an upper second metal film 50 (FIG. 7C). Next, the first and second metal films 49a and 50 are
By heating at 0 ° C. for several minutes (for example, about 3 minutes), the impurities in the upper first metal film 49a are diffused into both the upper metal films 49a, 50, and the impurities in the upper metal films 49a, 50 are diffused. Of the third metal film 51 as an upper wiring
And At this time, the impurity concentration of the third metal film 51 is about 1/3 of the first metal film 49a, that is, 2% (FIG. 7).
(D)).

According to the method of manufacturing the semiconductor device of the sixth embodiment performed as described above, not only the lower wiring 25 but also the third metal film 51 as the upper wiring is the same as in the first embodiment. Similar effects can be obtained. In addition, unlike the conventional case where the impurity concentration is set higher from the lower layer to the upper layer in the multilayer wiring, it is not necessary to change the impurity concentration in the multilayer wiring, so that it is possible to cope without limitation.

Although the sixth embodiment has been described with reference to the first embodiment for convenience, it is needless to say that the present invention is not limited to this and can be similarly applied to other embodiments. .

In each of the above embodiments, C is used as an impurity.
Although an example using u has been shown, the present invention is not limited to this.
It goes without saying that any element that has a eutectic reaction with 1 can be similarly used. Among them, G
e, or Mg, Ga, or the like can be easily used like Cu.

In each of the above embodiments, an example is shown in which a barrier metal film is provided between the first metal film and the interlayer insulating film. However, the present invention is not limited to this. It may be used as appropriate.

In each of the above embodiments, the second metal film is made of Al
Although an example in which the film is formed by a film is shown, the impurity concentration of the second metal film is lower than the impurity concentration of the first metal film (for example, C
If u is formed (contains 0.5%), the impurity concentration of the third metal film can be lower than that of the first metal film. This is because a device for forming only an Al film is not required at the stage of manufacturing a semiconductor device,
It leads to cost reduction.

[0049]

As described above, according to the first aspect of the present invention, the first metal film including Al having an element having a eutectic reaction with Al is laminated on the interlayer insulating film having the concave portion. And
The first metal film is heated, the first metal film is buried in the concave portion, and an element having a concentration lower than the concentration of the element contained in the first metal film is contained in Al on the first metal film. Or
A second metal film that is not included is laminated, the first and second metal films are heated to diffuse the elements, and the concentrations of the elements in the first and second metal films are made equal to each other to form a third metal film. Accordingly, it is possible to provide a method of manufacturing a semiconductor device in which the recess can be filled with a third metal film having a low element concentration.

According to a second aspect of the present invention, in the first aspect, the lamination of the first metal film is performed while heating, so that the first metal film is simultaneously buried in the recess. Therefore, it is possible to provide a method for manufacturing a semiconductor device in which the number of steps can be reduced.

According to a third aspect of the present invention, in the first or second aspect, the lamination of the second metal film is performed while heating, so that the first and second metal films are not laminated. Since a third metal film is formed by simultaneously diffusing elements and making the concentrations of the elements in the second and first metal films the same, it is possible to provide a method of manufacturing a semiconductor device in which the number of steps can be reduced. It is.

According to a fourth aspect of the present invention, in any one of the first to third aspects, after the first metal film is buried in the concave portion, the first metal film formed in a portion other than the concave portion is formed.
Since the metal film is removed, it is possible to provide a method for manufacturing a semiconductor device that can further reduce the concentration of impurities in the third metal film.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the thickness of the third metal film is reduced by etching, so that other portions are affected. It is possible to provide a method for manufacturing a semiconductor device which can surely reduce the impurity concentration of the third metal film without any problem.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, a barrier metal film is formed between the first metal film and the interlayer insulating film. It is possible to provide a method of manufacturing a semiconductor device which can prevent the substance of the metal film from moving to another place.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the element having a eutectic reaction with Al is Cu, Ge, Mg, or Ga. Since either of them is used, it is possible to provide a method of manufacturing a semiconductor device that can easily reduce the temperature at which the liquid phase of Al appears.

According to an eighth aspect of the present invention, there is provided a method of manufacturing a semiconductor device according to any one of the first to seventh aspects, wherein the upper wiring layer is formed on the lower wiring layer and the lower wiring layer. When used for the provided multilayer wiring, the concentration of the element in the upper first metal film is higher than the concentration of the element in the lower third metal film, so that the lower third metal film flows. It is possible to provide a method for manufacturing a semiconductor device in which an upper third metal film can be formed without performing the method.

[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 the method for manufacturing the semiconductor device of the first embodiment of the present invention.

FIG. 3 is a sectional view illustrating a method of manufacturing a semiconductor device according to a second embodiment of the present invention;

FIG. 4 is a sectional view illustrating a method of manufacturing a semiconductor device according to a third embodiment of the present invention;

FIG. 5 is a sectional view illustrating a method of manufacturing a semiconductor device according to a fourth embodiment of the present invention;

FIG. 6 is a sectional view illustrating a method for manufacturing a semiconductor device according to a fifth embodiment of the present invention;

FIG. 7 is a sectional view illustrating a method of manufacturing a semiconductor device according to a sixth embodiment of the present invention;

FIG. 8 is a phase diagram of Al—Cu.

FIG. 9 is a cross-sectional view illustrating a method for manufacturing a conventional semiconductor device.

FIG. 10 is a cross-sectional view illustrating another conventional method for manufacturing a semiconductor device.

FIG. 11 is a view showing a problem of a conventional method of manufacturing a semiconductor device.

FIG. 12 is a cross-sectional view illustrating a method for manufacturing another conventional semiconductor device.

[Explanation of symbols]

19, 38 interlayer insulating film, 20 contact holes, 21, 21a, 40 barrier metal film, 22, 22a, 22b, 34, 41, 41a first metal film, 23, 28, 31, 42 second metal film, 24, 26, 29, 32, 32a, 35, 43 Third metal film, 39 wiring trench, 46 upper interlayer insulating film, 47 upper contact hole, 48 upper barrier metal film, 49, 49a first upper layer 50, a second metal film on the upper layer, 51 a third metal film on the upper layer.

Claims (8)

[Claims] An Al film is formed on an interlayer insulating film having a recess.
stacking a first metal film containing an element having a eutectic reaction with the first metal film, heating the first metal film and embedding the first metal film in the concave portion, On the first metal film, Al contains the concentration of the element lower than the concentration of the element contained in the first metal film, or
A step of laminating a second metal film not included, and heating the first and second metal films to diffuse the elements, thereby making the concentrations of the elements in the first and second metal films the same. Forming a third metal film. 2. The method according to claim 1, further comprising the step of simultaneously burying the first metal film in the concave portion by performing the lamination of the first metal film while heating. A method for manufacturing a semiconductor device. 3. The lamination of the second metal film is performed while heating, whereby the elements in the first and second metal films are simultaneously diffused, and the second metal film and the second metal film in the first metal film are diffused. 3. The method for manufacturing a semiconductor device according to claim 1, further comprising the step of forming a third metal film with the same element concentration. 4. The method according to claim 1, further comprising, after embedding the first metal film in the recess, removing the first metal film formed outside the recess. The method for manufacturing a semiconductor device according to any one of the above. 5. The method of manufacturing a semiconductor device according to claim 1, further comprising the step of reducing the thickness of the third metal film by etching. 6. The method according to claim 1, further comprising the step of forming a barrier metal film between the first metal film and the interlayer insulating film. Method. 7. An element having a eutectic reaction with Al as C
7. The method for manufacturing a semiconductor device according to claim 1, wherein any one of u, Ge, Mg, and Ga is used. 8. The method of manufacturing a semiconductor device according to claim 1, wherein the method is used for a lower wiring layer and a multilayer wiring having an upper wiring layer on the lower wiring layer. A method of manufacturing a semiconductor device, wherein the concentration of an element in the upper first metal film is higher than the concentration of an element in the lower third metal film.