JPH09289212A - Laminated wiring of semiconductor device and its fabrication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low resistance high EM resistance wiring in a laminate structure of an Al alloy and high melting point metal or a high melting point metal compound by controlling the thickness of an alloying reaction layer of an interface formed by a heat treatment process to an optimum value. SOLUTION: A Ti film 2 is formed on a substrate 1 with sputtering, and then Ar ion sputtering etching is performed. An AlSiCu film 3 is formed on the Ti film 2, and Ar ion sputtering etching is performed. Further, a Ti film 4 is formed with sputtering, and then a TiN film 5 is formed with reactive sputtering. The laminate wiring is patterned with ordinary lithography and dry etching. Sintering heat treatment is performed in N2 gas atmospehere, and Al-Ti alloy reaction layers 6 and 7 are formed on an interface of the Al alloy film and the Ti film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring structure and a method of manufacturing the wiring structure for reducing the resistance of the wiring of a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, as a wiring material for a semiconductor device, an aluminum alloy, that is, an aluminum (hereinafter referred to as Al) simple substance or an Al alloy containing a trace amount of silicon or copper has been widely used. However, since the current density of wiring increases as semiconductor devices become highly integrated and miniaturized, electromigration (hereinafter abbreviated as EM) resistance and stress migration (hereinafter SM) are used when a single-layer Al alloy is used as a wiring material. (To be abbreviated.) Insufficient resistance may cause problems in reliability. As a countermeasure against this, a method of improving the EM resistance and the SM resistance by adopting a laminated structure of an Al alloy and a refractory metal such as titanium (hereinafter referred to as Ti) or a compound of these refractory metals is commonly used recently. It has become.

Generally, a high melting point metal or a high melting point metal compound has a higher resistance than an Al alloy, so that the wiring resistance as a whole becomes higher. Further, in such a laminated structure, the refractory metal or refractory metal compound and Al
Since the alloying reaction with the alloy is promoted, the volume of the Al alloy layer having a low resistance is reduced, which causes a problem that the wiring resistance is further increased.

For example, Al and Ti undergo an alloying reaction by heat treatment at 400 ° C. or higher, and an Al--Ti alloy (Al ₃ Ti)
Are formed at the interface. After forming the laminated wiring, heat treatment of 400 ° C. or more for about 20 to 30 minutes is required as a sintering treatment, and an Al—Ti alloy having a considerable film thickness is formed. The specific resistance of Al is about 3 μΩ · cm, Al−
Since the Ti alloy has a resistance of about 40 μΩ · cm, the wiring resistance value increases as much as the Al film thickness is reduced and the Al—Ti alloy is formed.

To solve the problem of increasing the wiring resistance, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-152445, a lower wiring structure is formed from the lower side with Al or an Al alloy layer and tantalum (hereinafter referred to as Ta). ) Layer and a barrier layer such as titanium nitride (hereinafter referred to as TiN).
From the lower side of the upper wiring structure, a barrier layer such as TiN, a Ta layer,
There is a structure in which an alloying reaction between Al and a refractory metal or a refractory metal compound is prevented by adopting a laminated wiring structure having a three-layer structure composed of Al or an Al alloy layer.

[0006]

As described above, when a Ta layer is provided between the Al alloy and the refractory metal or refractory metal compound in order to prevent this alloying reaction, Ta
The presence of the layer does not cause any alloying reaction between the Al alloy layer and the refractory metal or refractory metal compound. It is generally known that the alloying reaction layer formed by the above-mentioned alloying reaction improves the EM resistance of the wiring. If the alloying reaction layer is not formed at all, the EM resistance is deteriorated and reliability is deteriorated. It becomes a serious problem.

According to the present invention, in a laminated structure of an Al alloy and a refractory metal or a refractory metal compound, an alloying reaction layer of the Al alloy and the refractory metal or a refractory metal compound formed by a heat treatment step has a predetermined structure. We have realized a method and structure that can be controlled so that the ratio becomes low, and as a result, low resistance and E
It is an object to provide a wiring having high M resistance.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a laminated wiring of a semiconductor device in which a refractory metal is provided on the upper and lower surfaces of Al-based alloy wiring or on one of the surfaces thereof. An alloy reaction layer is formed, the Al-based alloy wiring, the high melting point metal, and the alloy reaction layer all contain argon, and the alloy reaction layer contains more argon than either the Al-based alloy wiring or the high melting point metal. Is more than double.

In an embodiment of the present invention, the refractory metal is Ti and the alloy reaction layer is Al containing argon.
-Ti alloy.

Further, according to the present invention, a refractory metal layer is formed on a substrate or an insulating film by a sputtering method, the refractory metal layer is subjected to sputter etching with argon ions, and then sputtered on the refractory metal layer. An Al-based alloy layer is formed by the method, and an alloy reaction layer containing argon is formed at the interface between the refractory metal layer and the Al-based alloy layer by the subsequent heat treatment.

Further, according to the present invention, an Al-based alloy layer is formed on a substrate or an insulating film by a sputtering method, the Al-based alloy layer is sputter-etched with argon ions, and then the Al-based alloy layer is sputtered. A refractory metal layer is formed by a method, and an alloy reaction layer containing argon is formed at the interface between the refractory metal layer and the Al-based alloy layer by subsequent heat treatment.

Further, according to the present invention, in a laminated wiring of a semiconductor device in which a refractory metal compound is provided on the upper and lower surfaces of Al-based alloy wiring or on one of the surfaces, an alloy reaction layer is formed between the Al-based alloy wiring and the refractory metal compound. Are formed, and the alloy reaction layer contains nitrogen.

In another embodiment of the present invention, the refractory metal compound is titanium-rich titanium nitride (TiN).
_X , 0 <X <1) and the alloy reaction layer is an Al—Ti alloy containing nitrogen.

In the present invention, a refractory metal compound layer containing nitrogen is formed on a substrate or an insulating film by a sputtering method, and then an Al-based alloy layer is formed on the refractory metal compound layer by a sputtering method. An alloy reaction layer containing nitrogen is formed at the interface between the refractory metal compound layer and the Al-based alloy layer by subsequent heat treatment.

Further, according to the present invention, an Al type alloy layer is formed on a substrate or an insulating film by a sputtering method, and then the Al type alloy layer is formed.
A refractory metal compound layer containing nitrogen is formed on the system alloy layer by a sputtering method, and an alloy reaction layer containing nitrogen is formed at the interface between the refractory metal compound layer and the Al system alloy layer by subsequent heat treatment. Is characterized by.

[0016]

According to the present invention, in the laminated wiring of the semiconductor device in which the refractory metal is provided on the upper and lower surfaces of the Al-based alloy wiring or on one of the surfaces, the Al-based alloy wiring or the refractory metal is preliminarily containing argon. A predetermined amount of alloying reaction occurs during heat treatment. This argon has a function of suppressing the alloying reaction, and for example, refractory metal has T
When i is used, it is partially incorporated in the alloy reaction layer Al—Ti alloy formed by heat treatment.
Therefore, the film thickness of the alloy reaction layer formed by the heat treatment can be optimally controlled, and a laminated wiring having a low resistance can be obtained without deteriorating the EM resistance.

According to another aspect of the present invention, a refractory metal compound containing nitrogen is used in a laminated wiring of a semiconductor device in which a refractory metal compound is provided on the upper and lower surfaces or one or both surfaces of an Al-based alloy wiring. For example, titanium-rich titanium nitride in which Ti is slightly mixed with nitrogen is used. The alloying reaction between Al and Ti occurs from about 400 ° C., whereas the alloying reaction between Al and TiN requires a temperature near 600 ° C. Therefore, the alloying reaction between Al and Ti by the titanium-rich titanium nitride is performed. Is suppressed. Thereby, the film thickness of the alloy reaction layer formed by the heat treatment can be optimally controlled, and the laminated wiring having a low resistance can be obtained without deteriorating the EM resistance.

[0018]

EXAMPLE As a first example, in a laminated wiring in which a Ti layer of a refractory metal is provided on both upper and lower surfaces of an Al alloy layer,
An Al-Ti alloy reaction layer is formed at the interface, and the alloy reaction layer has a composition in which the content of argon is twice or more that of the Al alloy layer and the Ti layer.

As shown in the sectional view of the structure of FIG. 1, a patterned wiring is formed on a substrate 1, and a Ti layer 2 is formed from the substrate side and a small amount of silicon (hereinafter referred to as Si) in Al as an Al alloy. And an AlSiCu layer 3 and a Ti layer 4 containing copper (hereinafter referred to as Cu). Further, a TiN layer 5 is provided as an antireflection film on the uppermost surface. At the interface between the AlSiCu layer 3 and the Ti layers 2 and 4, Al-Ti alloy reaction layers (Al ₃ Ti layer) 6 and 7 are formed.
Are formed.

This Al--Ti alloy reaction layer (Al ₃ Ti
Layers 6 and 7 are the film composition and argon (hereinafter Ar)
As shown in the figure showing the content, the Ar content is A
It is configured to be more than twice as large as any of the 1SiCu layer 3 and the Ti layers 2 and 4. The substrate 1 may be an insulating film.

A method of manufacturing the structure of the first embodiment will be described. Using a multi-chamber sputtering apparatus equipped with a pretreatment chamber (for sputter etching), an Al alloy film forming chamber, and a Ti and TiN film forming chamber, laminated wiring is formed in the order of (A) to (H) shown in FIG. A film is formed, and finally heat treatment is performed to form an Al-Ti alloy reaction layer.

(A) A Ti film 2 having a thickness of 20 nm is formed on the substrate 1 by sputtering Ti using Ar gas.
(B) 600 W, 30 se at ion energy of 2 keV
Ar ion sputter etching treatment of c is performed. (C)
As an Al alloy, A containing a trace amount of Si and Cu in Al
An AlSiCu film 3 of 500 nm is formed by sputtering using ArSiCu Ar gas. (D) 600 W, 30 sec Ar with ion energy of 2 keV
Ion sputter etching processing is performed.

(E) A Ti film 4 having a thickness of 20 nm is formed by sputtering Ti using Ar gas. (F) Ar
Ti using gas and nitrogen gas (hereinafter referred to as N ₂ gas)
TiN film 5 is removed by reactive sputtering of
0 nm is formed. (G) This laminated wiring is patterned by ordinary lithography and dry etching. (H) N ₂ gas atmosphere, 420 ° C., 20
Sinter heat treatment of min is performed to form Al—Ti alloy reaction layers 6 and 7 at the interface between the Al alloy film and the Ti film.

Although the Ti film is formed on the substrate (such as Si) in (A) in the above description, the steps after (A) are formed on the insulating film formed on the substrate or other wiring. May be carried out. In addition, the Ar ion sputter etching process performed in (B) and (D) is not for cleaning the surface, but for the effect of implanting Ar ions. Since the implantation energy is small, only the surface is very small. Argon will be included. The ion energy for this purpose is preferably 0.5 to 3.0 keV.
The TiN film (F) is formed as an antireflection film for lithography.

As described above, A is formed on both the upper and lower surfaces of the Al alloy.
In addition to the case where the 1-Ti alloy reaction layer is formed (this is referred to as (1)), the case where the Al-Ti alloy reaction layer is formed on either the upper surface or the lower surface of the Al alloy (of the Al alloy). The case of being formed on the upper surface will be described as (2), and the case of being formed on the lower surface as (3). In this case as well, a multi-chamber sputtering apparatus is used to form a laminated wiring in the same manner as above, and finally heat treatment is performed to form an Al—Ti alloy reaction layer. In the case of the above (2), the above steps (C) to (H) are performed on the substrate or the insulating film.
In the case of (3), the steps (A) to (C) and (F) to (H) are similarly performed on the substrate or the insulating film.

Experiments were also conducted in the case where the treatments were carried out in the respective steps (1), (2) and (3) and the Ar ion sputter etching treatment was not carried out. Further, T
Experiments were also performed in the case where the Al—Ti alloy reaction layer was not formed without sputtering the i film, and samples for evaluation under each condition were prepared.

The sheet resistance value of the wiring of each sample, A
FIG. 4 shows the evaluation of the residual film thickness and EM resistance (EM life). From this result, when the Ar ion sputter etching treatment is performed, the alloying reaction between the Al alloy film and the Ti film is suppressed, and the increase in wiring resistance is small and A
It can be seen that the residual film thickness is large. The EM resistance is almost the same as that when the Ar ion sputter etching process is not performed, and a value with no problem is obtained. Further, FIG. 5 schematically shows changes in the composition in the film thickness direction and the Ar content before and after the sintering heat treatment in (1) in the first embodiment.

Next, as a second embodiment, in a laminated wiring in which titanium-rich titanium nitride (TiN _x , 0 <X <1) of a refractory metal compound is provided on both the upper and lower surfaces of an Al alloy, the interface is The case where the Al—Ti alloy reaction layer is formed and the alloy reaction layer contains nitrogen will be described.

As shown in the sectional view of the structure of FIG.
The patterned wiring is formed on the upper side, and the TiN _X layer 12, the AlSiCu layer 13, the TiN _X layer are formed from the substrate side.
A layer 14 is provided. Further, a TiN layer 15 is provided on the uppermost surface as an antireflection film. And AlSi
At the interface between the Cu layer 13 and the TiN _X layers 12 and 14, Al-
Ti alloy reaction layers (Al ₃ Ti layers) 16 and 17 are formed.

This Al--Ti alloy reaction layer (Al ₃ Ti
The layers 16 and 17 contain nitrogen, as shown in FIG. 7 showing the film composition and the N content, but have a lower nitrogen content than the TiN film. The substrate 11
May be an insulating film.

Next, a method for manufacturing the structure of the second embodiment will be described. The process flow is that there is no Ar ion sputter etching treatment in the first embodiment and that T
The same except that TiN _x is formed instead of i. Using a multi-chamber sputtering apparatus equipped with an Al alloy film forming chamber and a Ti and TiN film forming chamber, a laminated wiring is formed into a film in the order of (A) to (F) shown in FIG. Then, an Al-Ti alloy reaction layer is formed.

(A) Ar gas and N ₂ gas were used on the substrate 11 (the N ₂ gas flow rate here is 10% of the total gas flow rate).
% Of Ti) to form a TiN _X (0 <X <1) film 12 with a thickness of 20 nm.
(B) An AlSiCu film 13 having a thickness of 500 nm is formed by sputtering AlSiCu using Ar gas.
(C) A TiN _X (0 <X <1) film 14 having a thickness of 20 nm is formed by reactive sputtering of Ti using Ar gas and N ₂ gas (the N ₂ gas flow rate here is 10% of the total gas flow rate). To do.

(D) Ar gas and N ₂ gas were used (N ₂ gas flow rate here is 40% of the total gas flow rate) T
TiN film 15 by reactive sputtering of i
Of 40 nm is formed. (E) This laminated wiring is patterned by ordinary lithography and dry etching. (F) In a N ₂ gas atmosphere, 420 ° C., 2
Sinter heat treatment for 0 min is performed to form Al—Ti alloy reaction layers 16 and 17 at the interface between the Al alloy film and the Ti film.

In the above description (A), the TiN _X film is formed on the substrate (such as Si). However, after (A) is formed on the insulating film formed on the substrate or another wiring. You may implement a process.

Generally, the TiN film is formed by reactive sputtering using a mixed gas of Ar gas and N ₂ gas. In this method, the composition of TiN is controlled by changing the flow rate ratio of N ₂ gas. be able to. N
_{If 2} gases are sufficiently supplied, a TiN film having a stoichiometric composition of Ti and N of 1: 1 is obtained, and if the flow rate of N ₂ gas is zero, a pure Ti film is formed. In the sputtering device used in this experiment, the flow rate of N ₂ gas was 30% of the total gas flow rate.
A TiN film with a composition ratio of 1: 1 is obtained as described above, and a Ti-rich TiN _X (0 <X <1) film is obtained below that.
The TiN film (D) is formed as an antireflection film for lithography.

As described above, A is formed on both the upper and lower surfaces of the Al alloy.
In addition to the case where the 1-Ti alloy reaction layer is formed (this is referred to as (4)), the case where the Al-Ti alloy reaction layer is formed on either the upper surface or the lower surface of the Al alloy (of the Al alloy). The case of forming on the upper surface (5) and the case of forming on the lower surface (6) will be described. In this case as well, a multi-chamber sputtering apparatus is used to form a laminated wiring in the same manner as above, and finally heat treatment is performed to form an Al—Ti alloy reaction layer. In the case of (5), the steps (B) to (F) are performed on the substrate or the insulating film.
In the case of (6), the steps (A) to (B) and (D) to (F) are performed on the substrate or the insulating film.

The treatment was carried out in each of the above steps (4), (5) and (6). Further, in each of the steps (A) and (C) in the above steps (A) to (F), the Ti film is formed instead of the Ti-rich TiN _X film by setting the flow rate of the N ₂ gas to zero. The experiment was also conducted for the case. Further, an experiment was conducted in the case where neither Ti-rich TiN _X film nor Ti film was sputtered and the Al—Ti alloy reaction layer was not formed, and samples for evaluation under each condition were prepared.

The sheet resistance value of the wiring of each sample, A
FIG. 9 shows the evaluation of the residual film thickness and the EM resistance (EM life). From this result, by using a Ti-rich TiN _X (0 <X <1) film instead of Ti, the alloying reaction between the Al alloy film and the Ti film is suppressed, the increase of the wiring resistance is small, and the Al resistance is small. It can be seen that the residual film thickness is thick. The EM resistance is almost the same as when the Ti film is formed instead of the Ti-rich TiN _X film, and a value with no problem is obtained. Further, FIG. 10 schematically shows changes in the composition in the film thickness direction and the N content before and after the sinter heat treatment in the above (4).

In the above embodiment, TiN _X (0 <
X <1) The N ₂ gas flow rate is constant during film formation.
The N ₂ gas flow rate during film formation may be continuously or stepwise changed so that the nitrogen content near the 1-alloy becomes smaller.

In the embodiment described above, Al-T
Although argon and nitrogen are individually used as impurities for suppressing the formation of the i alloy, the same effect can be obtained by using both of them at the same time. Even when the Ti film or the Ti-rich TiN _X film is thin and all of it reacts with the Al-based alloy by heat treatment to form an Al-Ti alloy reaction layer, the same effect can be obtained. Further, as the refractory metal, besides Ti, a metal that causes an alloying reaction with Al by heat treatment at about 400 ° C., such as hafnium (Hf), vanadium (V), and chromium (Cr), can be applied. .

[0041]

According to the present invention, the alloy reaction layer of Al-based alloy wiring and refractory metal or refractory metal compound contains argon or nitrogen, or Al-based alloy wiring and refractory metal or refractory metal compound. Since the interface is made to contain argon or nitrogen and heat-treated to optimally control the film thickness of the alloy reaction layer, it is possible to obtain a laminated wiring having a low resistance without deteriorating the EM resistance. Further, the introduction of the above-mentioned argon or nitrogen into the above-mentioned interface can be carried out with almost no increase in the number of steps and the process cost since a multi-chamber sputtering apparatus which is usually used can be used.

[Brief description of drawings]

FIG. 1 is a structural cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a diagram showing the film composition and Ar content in the first example of the present invention.

FIG. 3 is a process sectional view showing the method of manufacturing the wiring according to the first embodiment of the present invention.

FIG. 4 is a chart showing evaluation results of the first example of the present invention.

FIG. 5 is a diagram showing changes in film composition and Ar content in the first example of the present invention.

FIG. 6 is a sectional view showing the configuration of a second embodiment of the present invention.

FIG. 7 is a diagram showing a film composition and N content in a second example of the present invention.

FIG. 8 is a process sectional view showing the method of manufacturing the wiring according to the second embodiment of the present invention.

FIG. 9 is a chart showing the evaluation results of the second example of the present invention.

FIG. 10 is a diagram showing changes in film composition and N content in the second example of the present invention.

[Explanation of symbols]

1, 11 Substrate 2, 4 Ti film 3, 13 AlSiCu film 5, 15 TiN film 6, 7, 16, 17 Al-Ti alloy reaction layer 12, 14 TiN _X (0 <X <1) film

Claims (8)

[Claims] 1. In a laminated wiring of a semiconductor device in which a refractory metal is provided on the upper and lower surfaces of an aluminum-based alloy wiring or on one surface thereof, an alloy reaction layer is formed between the aluminum-based alloy wiring and the refractory metal. The aluminum-based alloy wiring, the refractory metal and the alloy reaction layer all contain argon, and the alloy reaction layer has an argon content more than twice that of the aluminum-based alloy wiring and the refractory metal. Laminated wiring of a characteristic semiconductor device. 2. The refractory metal in claim 1 is titanium and the alloy reaction layer is aluminum containing argon.
A laminated wiring of a semiconductor device, which is a titanium alloy. 3. A refractory metal layer is formed on a substrate or an insulating film by a sputtering method, the refractory metal layer is sputter-etched with argon ions, and then aluminum is sputtered on the refractory metal layer. A method for manufacturing a laminated wiring of a semiconductor device, comprising: forming a system alloy layer, and then performing a heat treatment to form an alloy reaction layer containing argon at an interface between the refractory metal layer and the aluminum system alloy layer. 4. An aluminum-based alloy layer is formed on a substrate or an insulating film by a sputtering method, the aluminum-based alloy layer is subjected to sputter etching treatment with argon ions, and then the aluminum-based alloy layer is formed on the aluminum-based alloy layer by a sputtering method. A method for manufacturing a laminated wiring of a semiconductor device, which comprises forming a melting point metal layer and then forming an alloy reaction layer containing argon at the interface between the refractory metal layer and the aluminum alloy layer by heat treatment. 5. In a laminated wiring of a semiconductor device in which a refractory metal compound is provided on the upper and lower surfaces of an aluminum-based alloy wiring or on one surface thereof, an alloy reaction layer is formed between the aluminum-based alloy wiring and the refractory metal compound. And the alloy reaction layer contains nitrogen. 6. The refractory metal compound according to claim 5 is titanium-rich titanium nitride (TiN _x , 0 <X <1), and the alloy reaction layer is an aluminum-titanium alloy containing nitrogen. Stacked wiring for semiconductor devices. 7. A refractory metal compound layer containing nitrogen is formed on a substrate or an insulating film by a sputtering method, and then an aluminum alloy layer is formed on the refractory metal compound layer by a sputtering method. A method for manufacturing a laminated wiring of a semiconductor device, which comprises forming an alloy reaction layer containing nitrogen at an interface between the refractory metal compound layer and the aluminum alloy layer by heat treatment. 8. An aluminum-based alloy layer is formed on a substrate or an insulating film by a sputtering method, and then a refractory metal compound layer containing nitrogen is formed on the aluminum-based alloy layer by a sputtering method, followed by heat treatment. An alloy reaction layer containing nitrogen is formed at an interface between the refractory metal compound layer and the aluminum-based alloy layer by a method for manufacturing a laminated wiring of a semiconductor device.