JP3096551B2 - Method for manufacturing semiconductor device - Google Patents

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.
More specifically, the present invention relates to a method for manufacturing a multilayer wiring structure.

[0002]

2. Description of the Related Art In recent years, multi-layer wirings employed in highly integrated semiconductor devices include inter-wiring contacts (via contacts).
, There is a demand for lowering the resistance and improving the reliability of wiring.
7 to 9 are cross-sectional views illustrating a conventional multi-layer wiring manufacturing process using a two-layer wiring as an example. Hereinafter, the manufacturing process will be described step by step.

Process 1 (see FIG. 7): A silicon oxide film 2 as an insulating film is deposited on a surface of a single-crystal silicon substrate 1 by an appropriate thickness (for example, 600 nm) by a CVD (chemical vapor deposition) method. . Next, by sputtering, a titanium thin film 3, a titanium nitride (TiN) thin film 4, an aluminum alloy thin film 5 as a first layer wiring, and a titanium nitride thin film 6 are sequentially formed on the surface of the Si oxide film 2 by an appropriate thickness. Deposit (for example, titanium thin film 3:50 nm, titanium nitride thin film 4: 100 nm, aluminum alloy thin film 5: 500 n)
m, titanium nitride thin film 6: 20 nm).

Subsequently, wiring patterning is performed using ordinary photolithography technology. Then, a wiring pattern of the first layer wiring is formed by dry etching. Here, the aluminum alloy thin film 5 is obtained by adding another metal or a high melting point metal to pure aluminum (for example, Al-S
i (1%)-Cu (0.5%), Al-Cu, Al-M
g). By using an aluminum alloy instead of pure aluminum in this way, electromigration (a phenomenon of disconnection due to the movement of aluminum atoms due to an electron flow, as described later) and stress migration (a phenomenon of disconnection due to stress only by heat) can be achieved. Migration can be prevented.

The reason why the titanium nitride thin film 4 is formed under the aluminum alloy thin film 5 is to prevent Al and Si from reacting to break the junction. That is, when heat treatment is performed after the formation of the first layer wiring, the aluminum in the aluminum alloy thin film 5 reacts with the polycrystalline Si substrate 1 in the contact hole 8 (also referred to as a via hole or via contact). Then, Al and Si form a eutectic, but the Si is supplied from the Si substrate 1 so that the junction is broken. Therefore, the reaction at the interface is prevented by forming the titanium nitride thin film 4 below the aluminum alloy thin film 5.

Further, the reason why the titanium thin film 3 is formed under the titanium nitride thin film 4 is that if only the titanium nitride thin film 4 is used, the contact resistance becomes high. Thus, the titanium nitride thin film 4 and the titanium thin film 3 function as a barrier metal. The reason why the titanium nitride thin film 6 is formed on the aluminum alloy thin film 5 is to prevent reflection from the aluminum alloy thin film 5 during exposure in photolithography. That is, the titanium nitride thin film 6 functions as an antireflection film (cap metal).

Process 2 (see FIG. 8): An appropriate thickness (for example, 600 nm) of an Si oxide film 7 as an interlayer insulating film is deposited on the surface of the titanium nitride thin film 6 of the first layer wiring by the CVD method. Next, patterning of the contact hole is performed using a normal photolithography technique. Then, a contact hole 8 is formed by dry etching.

Process 3 (see FIG. 9): By sputter etching using an inert gas (eg, argon),
The etching scum in the contact hole 8 and the oxide film on the surface of the titanium nitride thin film 6 of the first wiring layer in the contact hole 8 are removed. Next, by sputtering, a titanium nitride thin film 9, an aluminum alloy thin film 10 as a second layer wiring, and a titanium nitride thin film 11 are sequentially deposited on the surface of the Si oxide film 7 and in the contact holes 8 by an appropriate thickness. (For example, titanium nitride thin film 9: 100n
m, aluminum alloy thin film 10: 500 nm, titanium nitride thin film 11: 20 nm).

Subsequently, patterning of the wiring is performed using a normal photolithography technique. Then, a wiring pattern of the second wiring layer is formed by dry etching, and the manufacturing process of the two-layer wiring is completed. Here, the aluminum alloy thin film 10 is obtained by adding another metal or a high melting point metal to pure aluminum for the same reason as the aluminum alloy thin film 5 (for example, Al-Si (1%)-Cu (0. 5%),
Al-Cu, Al-Mg).

The titanium nitride thin film 11 on the aluminum alloy thin film 10 functions as an anti-reflection film similarly to the titanium nitride thin film 6. Further, the reason why the titanium nitride thin film 9 is formed under the aluminum alloy thin film 10 is to suppress the growth of hillocks caused by heat treatment such as sintering.
That is, since the short-circuit of the wiring is induced by the growth of the hillock, the growth of the hillock is suppressed by forming the titanium nitride thin film 4 below the aluminum alloy thin film 10.

When an alloy of Al and Si is used for the aluminum alloy thin film 10, Si in the aluminum alloy thin film 10 in the contact hole 8 may be precipitated by heat treatment and the contact resistance may be increased. The reason why the titanium nitride thin film 9 is formed under the aluminum alloy thin film 10 is also to prevent it. By the way, in recent years, the integration of the semiconductor device has been more and more advanced, and it is required to reduce the diameter of the contact hole 8. However, if the diameter of the contact hole 8 is reduced,
It becomes difficult to deposit the titanium nitride thin film 9 and the aluminum alloy thin film 10 having a sufficient thickness inside. Therefore, it has been proposed to deposit a suitable metal (tungsten, aluminum, nickel, copper, or the like) in the contact hole 8 by a CVD method to form a plug for connecting the first layer wiring and the second layer wiring. I have.

FIG. 7, FIG. 8, FIG. 10, and FIG. 11 are sectional views showing a manufacturing process when a tungsten plug 12 is buried in the contact hole 8 in the manufacturing process of the two-layer wiring. Hereinafter, the manufacturing process will be described step by step. Process A (see FIG. 7): The process is the same as the process 1, and the description is omitted.

Process B (see FIG. 8): Process 2
Therefore, the description is omitted. Process C (see FIG. 10): The sputter etching using an inert gas (for example, argon) removes the etching scum in the contact hole 8 and the oxide film on the surface of the titanium nitride thin film 6 of the first layer wiring in the contact hole 8. Remove.

Next, a titanium nitride thin film 9 is deposited to a suitable thickness (for example, 100 nm) on the surface of the Si oxide film 7 and in the contact hole 8 by sputtering.
Then, by blanket tungsten-CVD method,
A tungsten thin film 12 is deposited on the surface of the titanium nitride thin film 9 by an appropriate thickness (for example, 500 nm). And
The entire surface is etched back so that only the tungsten thin film 12 in the contact hole 8 is left.
A tungsten plug 12 is formed therein.

Process D (see FIG. 11): Titanium nitride thin film 9 and tungsten plug 1 by sputtering
2, an aluminum alloy thin film 10 as a second layer wiring,
The titanium nitride thin films 11 are sequentially deposited with an appropriate thickness (for example, an aluminum alloy thin film 10: 500 nm, a titanium nitride thin film 11: 20 nm). Subsequently, patterning of the wiring is performed using a normal photolithography technique. Then, a wiring pattern of the second-layer wiring is formed by dry etching, and the manufacturing process of the two-layer wiring is completed.

Here, the aluminum alloy thin film 10 is obtained by adding another metal or a high melting point metal to pure aluminum for the same reason as the aluminum alloy thin film 5 (for example, Al—
Si (1%)-Cu (0.5%), Al-Cu, Al-
Mg). Further, the titanium nitride thin film 11 on the aluminum alloy thin film 10 functions as an antireflection film similarly to the titanium nitride thin film 6.

The reason why the titanium nitride thin film 9 is formed below the aluminum alloy thin film 10 is to suppress the growth of hillocks caused by electromigration as described above. Further, as described above, when the alloy of Al and Si is used for the aluminum alloy thin film 10, the silicon of the aluminum alloy thin film 10 in the contact hole 8 is prevented from being deposited and the contact resistance is prevented from increasing. .

Further, the titanium nitride thin film 9 is indispensable in the blanket tungsten-CVD method. That is,
In the blanket tungsten-CVD method, the tungsten thin film 12 may be peeled off without the titanium nitride thin film 9. That is, the titanium nitride thin film 9 functions as an adhesion layer when the tungsten thin film 12 is formed by the blanket tungsten-CVD method (the titanium thin film or the Si oxide film has poor adhesion to the tungsten thin film, If a tungsten thin film is formed directly on the film, the formed tungsten thin film may be separated.

[0019]

By the way, in the sputter etching in the processes 3 and C, if the etching scum in the contact hole 8 and the oxide film on the surface of the titanium nitride thin film 6 are to be completely removed, the titanium nitride thin film is removed. 6 itself is also removed. Then, the surface of the aluminum alloy thin film 5 as the first layer wiring (that is, the active aluminum surface) is exposed.

Therefore, when the titanium nitride thin film 9 is formed by sputtering, the surface of the active aluminum alloy thin film 5 exposed in the nitrogen atmosphere which is a reactive gas is exposed, and the surface of the aluminum alloy thin film 5 is nitrided. . Aluminum nitride (AlN) on the surface of the aluminum alloy thin film 5
There is a problem that the contact resistance in the contact hole 8 increases due to the layer. Even if the composition of the aluminum alloy thin film 5 is changed, as long as aluminum is contained, this problem still occurs to some extent.

The present invention relates to a method for manufacturing a semiconductor device ,
Such a problem is solved.

[0022]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a first barrier metal having a first titanium nitride film laminated on a first titanium film; and forming a first aluminum film on the first barrier metal. Alternatively, a first titanium film in which an aluminum alloy film is formed and a second titanium nitride film is laminated on a second titanium film
A first step of forming a cap metal, a second step of forming an interlayer insulating film on the first cap metal,
A third step of forming a contact hole in the interlayer insulating film, and sputter etching the inside of the contact hole.
Fourth step and a fifth step of forming a third titanium film within the contact and the interlayer insulating film hole, sixth Engineering of forming the third titanium nitride film on the third titanium film that
A seventh step of forming a second aluminum film or an aluminum alloy film on the third titanium nitride film; and a seventh step of forming a fourth titanium film on the second aluminum film or the aluminum alloy film. The gist is that the eighth step of forming the second cap metal on which the titanium tetranitride film is laminated is sequentially performed.

According to a second aspect of the present invention, there is provided a semiconductor device manufacturing method comprising:
Forming a first barrier metal in which a first titanium nitride film is laminated on a titanium film, forming a first aluminum film or an aluminum alloy film thereon, and forming a second titanium nitride film on a second titanium film; A first step of forming a first cap metal having a film laminated thereon, a second step of forming an interlayer insulating film on the first cap metal, and a third step of forming a contact hole in the interlayer insulating film. And the contour
A fourth step of sputter etching the inside of the
A fifth step of forming a third titanium film in the contact hole and on the interlayer insulating film, a sixth step of forming a third titanium nitride film on the third titanium film, A seventh step of embedding a metal plug; an eighth step of forming a second aluminum film or an aluminum alloy film on the metal plug and the third titanium nitride film; The ninth step of forming a second cap metal in which a fourth titanium nitride film is stacked on a fourth titanium film on the alloy film is sequentially performed.

[0024]

According to the first and second aspects of the present invention,
Is used to form the second to fourth titanium nitride films.
The second to fourth titanium films formed under each are buffered.
Work as a key layer.

Therefore, in a nitrogen atmosphere which is a reactive gas,
The surface of aluminum under the second and fourth titanium films is further
Can be prevented.

Therefore, the surface of aluminum under the second and fourth titanium films is not nitrided.

Before forming the second titanium nitride film,
Be sure to form a second titanium film and a third titanium nitride film
Before the third layer is formed, the third titanium film is always formed.
And the contact resistance between the second layer wiring and the second layer wiring is greatly reduced.

Further, by providing a cap metal having a laminated structure composed of a titanium film and a titanium nitride film on the wiring layer, an excellent antireflection film corresponding to the thickness of the Ti film can be maintained while maintaining the function as an antireflection film. Electromigration resistance can be obtained.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is embodied in a two-layer wiring will be described below with reference to FIGS. 1, 4, 7, and 8. FIG.

Since the present embodiment corresponds to the problem of the two-layer wiring of the conventional example shown in FIGS. 7 to 9, the same reference numerals are used for the same parts as in the conventional example, and the description will be made. Omitted.

FIG. 1 is a longitudinal sectional view of the semiconductor device of this embodiment. A silicon oxide film 2 is formed on a single crystal silicon substrate 1.
Are formed. On the Si oxide film 2, a titanium thin film 3 is formed. On the Ti thin film 3, a titanium nitride thin film 4 is formed. On the titanium nitride thin film 4, an aluminum alloy thin film 5 as a first layer wiring is formed.
On the aluminum alloy thin film 5, a titanium nitride thin film 6 is formed. A silicon oxide film 7 is formed on the Ti nitride thin film 6. A contact hole 8 is formed in the Si oxide film 7. A titanium thin film 21 is formed on the surface of the aluminum alloy thin film 5 which is the bottom surface of the contact hole 8 and the Si oxide film 7 which is the inner side wall of the contact hole 8. On the Ti thin film 21, the titanium nitride thin film 9 is formed. An aluminum alloy thin film 10 as a second layer wiring is formed on the Ti nitride thin film 9. On the aluminum alloy thin film 10, a titanium nitride thin film 11 is formed.

Next, the manufacturing process of this embodiment will be described step by step. Process 1 (see FIG. 7): Since it is the same as the process 1 of the conventional example, the description is omitted. Process 2 (see FIG. 8): The process is the same as the process 2 of the conventional example, and the description is omitted.

Process 3 (see FIG. 1): By sputter etching using an inert gas (eg, argon)
The etching scum in the contact hole 8 and the oxide film on the surface of the titanium nitride thin film 6 of the first layer wiring in the contact hole 8 are removed. Next, by sputtering, a titanium thin film 21, a titanium nitride thin film 9, an aluminum alloy thin film 10 as a second layer wiring, and a titanium nitride thin film 11 are sequentially formed on the surface of the Si oxide film 7 and in the contact hole 8 to have an appropriate thickness. (Eg, titanium thin film 21: 50 nm, titanium nitride thin film 9: 100 nm, aluminum alloy thin film 10: 500 nm, titanium nitride thin film 11: 20 nm).

Subsequently, patterning of the wiring is performed by using a normal photolithography technique. Then, a wiring pattern of the second-layer wiring is formed by dry etching, and the manufacturing process of the two-layer wiring is completed. Here, the composition and the reason of the aluminum alloy thin film 10 and the function of the Ti nitride thin film 11 are the same as those of the conventional example, and therefore the description is omitted.

The formation of the titanium nitride thin film 9 below the aluminum alloy thin film 10 is, as described in the conventional example,
This is to suppress the growth of hillocks caused by electromigration. In this embodiment, 45
It was confirmed that hillocks did not occur even after heat treatment at 0 ° C. for 60 minutes. Thus, the present embodiment is different from the conventional example in that the Ti thin film 21 is formed before the Ti nitride thin film 9 is formed (that is, after the sputter etching).

FIG. 4 shows the change in the contact resistance of the contact hole 8 with respect to the sputter etching time using argon. The size of the contact hole is 0.8
× 1.0 μm. For reference, the titanium thin film 2
An example in which only 1 was formed and the titanium nitride thin film 9 was not formed, and an example in which both the titanium nitride thin film 9 and the titanium thin film 21 were not formed are also shown.

In the conventional example having no Ti thin film 21, the contact resistance sharply increases from a sputter etching time of about 80 seconds. It is considered that this is because the increase in the sputter etching time removes the Ti nitride thin film 6 and increases the degree of exposure of the surface of the aluminum alloy thin film 5. In other words, when the nitrided Ti thin film 9 is formed by sputtering, the surface of the active aluminum alloy thin film 5 exposed in the nitrogen atmosphere which is a reactive gas is exposed, and the surface of the aluminum alloy thin film 5 is nitrided. At this time, if the degree of exposure of the surface of the aluminum alloy thin film 5 is large, nitriding of the surface of the aluminum alloy thin film 5 is promoted. Therefore, the ratio of the aluminum nitride layer formed on the surface of the aluminum alloy thin film 5 to the area of the contact hole 8 increases, and the contact resistance increases.

On the other hand, in the present embodiment in which the Ti thin film 21 is provided, the contact resistance does not increase even if the sputter etching time increases. This is because the Ti thin film 21 formed before the formation of the Ti nitride thin film 9 (that is, before sputtering in a nitrogen atmosphere) functions as a buffer layer and prevents the surface of the aluminum alloy thin film 5 from being exposed to the nitrogen atmosphere. That's why.

FIG. 16 shows that TiN /
This is an evaluation of the difference in contact resistance when using a Ti laminated cap and a TiN single layer cap. Normal dry etching is used for etching the contact hole, and Ti (100 n) is used as a barrier metal for the second-layer wiring.
m). Sintering is performed at 400 ° C. for 30 minutes.

When the TiN / Ti laminated cap is used, the contact resistance is about 0.5 × 10 ⁻⁸ Ω as compared with the TiN single layer.
· Cm ² made it can be seen that small. Fig. 5 shows the contact interface between the upper and lower aluminum alloy thin films by X-ray photoemission spectroscopy (XPS).
2 shows the results of analysis by X-ray Photoelectron Spectroscopy). This is because the titanium nitride thin film 9 in FIG.
Example in which both of the i thin films 21 are not formed (that is, an example in which the aluminum alloy thin film 10 is directly formed on the aluminum alloy thin film 5)
Is equivalent to

FIG. 6 shows an example in which the contact interface between the aluminum thin film and the Ti nitride thin film is analyzed by XPS.
This corresponds to the conventional example without the Ti thin film 21 in FIG. In FIGS. 5 and 6, the intensity of the binding energy is plotted on the horizontal axis, and the detection intensity is plotted on the vertical axis.

As shown in FIG. 5, aluminum oxide and aluminum were detected from the contact interface between the upper and lower aluminum alloy thin films. On the other hand, as shown in FIG. 6, from the contact interface between the aluminum thin film and the titanium nitride thin film,
Aluminum nitride was detected in addition to aluminum oxide and aluminum. From these results, when the Ti nitride film 9 is formed by sputtering, the surface of the active aluminum alloy thin film 5 exposed in the nitrogen atmosphere, which is a reactive gas, is exposed, and the surface of the aluminum alloy thin film 5 is nitrided to form aluminum nitride. The formation of a layer is again confirmed.

As described above, in the present embodiment, by forming the Ti thin film 21, active aluminum (aluminum alloy thin film 5) is formed by sputtering in a nitrogen atmosphere.
When a Ti nitride film (Ti thin film 21) is formed thereon, nitriding of the aluminum surface can be prevented. (Second Embodiment) Next, a second embodiment in which the present invention is embodied in a two-layer wiring having a structure in which a tungsten plug is buried in a contact hole will be described with reference to FIGS. 2, 3, 7 and 8. explain.

This embodiment corresponds to the problem of the conventional example (two-layer wiring having a structure in which a tungsten plug is embedded in a contact hole) shown in FIGS. 7, 8, 10 and 11. Therefore, the same parts as those in the conventional example and the first embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 3 is a longitudinal sectional view of the semiconductor device of the present embodiment.

A silicon oxide film 2 is formed on a single crystal silicon substrate 1. On the Si oxide film 2, a titanium thin film 3 is formed. On the Ti thin film 3, a titanium nitride thin film 4 is formed. An aluminum alloy thin film 5 as a first wiring layer is formed on the titanium nitride thin film 4. On the aluminum alloy thin film 5, a titanium nitride thin film 6 is formed. A silicon oxide film 7 is formed on the Ti nitride thin film 6. A contact hole 8 is formed in the Si oxide film 7. A titanium thin film 21 is formed on the surface of the aluminum alloy thin film 5 which is the bottom of the contact hole 8 and the Si oxide film 7 which is the inner side wall of the via contact 8. On the Ti thin film 21, the titanium nitride thin film 9 is formed. A tungsten plug 12 is buried in the contact hole 8. An aluminum alloy thin film 10 as a second-layer wiring layer is formed on the tungsten plug 12 and the Ti nitride thin film 9. On the aluminum alloy thin film 10, a titanium nitride thin film 11 is formed.

Next, the manufacturing process of this embodiment will be described step by step. Process A (see FIG. 7): Since it is the same as Process 1 of the conventional example, the description is omitted. Process B (see FIG. 8): Since it is the same as Process 2 of the conventional example, the description is omitted.

Process C (see FIG. 2): By sputter etching using an inert gas (eg, argon)
The etching scum in the contact hole 8 and the oxide film on the surface of the titanium nitride thin film 6 of the first layer wiring in the contact hole 8 are removed. Next, by sputtering, the Ti thin film 21 and the titanium nitride thin film 9 are formed on the surface of the Si oxide film 7 and in the contact holes 8 by an appropriate thickness (for example, Ti thin film 21: 50n).
m, Ti nitride thin film 9: 100 nm).

Subsequently, blanket tungsten-CV
By the method D, the tungsten thin film 12 is deposited on the surface of the titanium nitride thin film 9 by an appropriate thickness (for example, 500 nm). Then, the entire surface is etched back so that only the tungsten thin film 12 in the contact hole 8 is left, and a tungsten plug 12 is formed in the contact hole 8.

Process D (see FIG. 3): Titanium nitride thin film 9 and tungsten plug 12 are formed by sputtering.
An aluminum alloy thin film 10 and a titanium nitride thin film 11 as a second wiring layer are sequentially deposited in appropriate thicknesses on the surface (for example, aluminum alloy thin film 10: 500 nm, titanium nitride thin film 11: 20 nm). Subsequently, patterning of the wiring is performed using a normal photolithography technique. Then, a wiring pattern of the second-layer wiring is formed by dry etching, and the manufacturing process of the two-layer wiring is completed.

Here, the composition and the reason of the aluminum alloy thin film 10 and the function of the Ti nitride thin film 9 and the Ti nitride thin film 11 are the same as those of the conventional example, and therefore, the description is omitted. The difference between the present embodiment and the conventional example is that the nitrided T
This is to form the Ti thin film 21 before forming the i thin film 9 (that is, after sputter etching). Thus, in this embodiment, similarly to the first embodiment, a Ti nitride film (Ti thin film 2) is formed on active aluminum (aluminum alloy thin film 5) by sputtering in a nitrogen atmosphere.
When forming 1), nitriding of the aluminum surface can be prevented. (Third Embodiment) By experiment, the present inventor has found that the titanium thin film 21 is formed in the contact hole 8 by the sputtering method without performing the sputter etching process in the first and second embodiments. ,
It was demonstrated that the oxide film on the bottom surface of the contact hole 8 was removed and the contact resistance could be reduced.

FIG. 12 shows the results of the experiment. In the figure, a: a case where a two-layer structure of a titanium thin film 22 and a titanium nitride thin film 6 is formed as a cap metal on the aluminum alloy film 10 in the process of the first embodiment (however, sputter etching is not performed). : When no sputter etching was performed in the process of the first embodiment c: In the case of the process of the first embodiment (that is, a two-layer structure of a titanium thin film 21 and a titanium nitride thin film 9 as a barrier metal) d: Conventional example In the process shown by (1), only titanium nitride was provided as the cap metal of the first wiring layer. E: The case where sputter etching was not performed in the process shown in the conventional example.

As can be seen by comparing FIGS. 12B and 12C, the contact resistance (interlayer connection hole resistance) is lower in the process b in which the sputter etching in the contact hole 8 is not performed. From this, it can be seen that when the purpose is to reduce the contact resistance (that is, when the removal of the etching scum in the contact hole 8 is neglected to some extent), the time for performing the sputter etching can be reduced.

Further, as in the device of FIG.
It can be seen that the contact resistance can be significantly reduced by using a two-layer structure of the titanium thin film 22 and the titanium nitride thin film 6 as the cap metal of the layer wiring. FIG. 13 is a cross-sectional view of the device of FIG.

A 600 nm silicon oxide film 2 is formed on a single crystal silicon substrate 1 by a CVD method.
On the Si oxide film 2, a 50 nm titanium thin film 3, a 100 nm titanium nitride thin film 4, and a 500 nm aluminum alloy thin film 5 are sequentially formed by magnetron sputtering. On the aluminum alloy thin film 5, titanium thin films 22 and 20 each having a thickness of 10 nm were also formed by magnetron sputtering.
A titanium nitride thin film 6 of nm is formed.

Thereafter, as in FIG. 1, a silicon oxide film 7 is formed, and a contact hole 8 is formed in this silicon oxide film 7.
Is formed, and a titanium thin film 21 is formed on the surface of the titanium nitride thin film 6 which is the bottom surface of the contact hole 8 and the Si oxide film 7 which is the inner side wall of the contact hole 8 without performing sputter etching. . On the Ti thin film 21, the titanium nitride thin film 9 is formed. An aluminum alloy thin film 10 as a second wiring layer is formed on the Ti nitride thin film 9.
Are formed.

Finally, a titanium thin film 23 and a titanium nitride thin film 11 are formed on the aluminum alloy thin film 10.
The two-layer structure of the titanium thin film 23 and the titanium nitride thin film 11 assumes that a wiring is further formed on the second-layer wiring, and in the present structure, the titanium nitride thin film 1
Only one is acceptable.

However, the cap metal is made of TiN
It has been found that the / Ti structure improves the electromigration resistance (EM resistance). FIG.
7 is an evaluation of the EM resistance of the TiN (20 nm) / Ti (30 nm) laminated cap and the TiN (20 nm) single-layer cap. All samples were 450
Sintering, sample temperature 250 ° C, current density 5 ×
The result of evaluation under the condition of 10 ⁶ A / cm ² was LOG-NOM
An AL plot was performed.

Under these test conditions, it can be seen that the life of the TiN / Ti laminated cap is improved about 10 times. FIG. 14 shows that TiN (20 nm) /
Ti (0 to 30 nm) / Al-Si-Cu (600 n
m, 200 ° C. film) // TiN (100 nm) / Ti
(50 nm) (ie, TiN11 in FIG. 13).
/ Ti23 / Al alloy thin film 10 // TiN9 / Ti21
Is formed on p-TEOS-NSG,
In addition, using the passivation of the p-SiN / PSG structure and changing the thickness of Ti from 0 to 30 nm in the TiN / Ti structure as the cap film, the average failure time (also referred to as the average life) (MTTF: Mean) Time To Failure)
Is measured.

It can also be seen from this figure that the EM resistance increases as the thickness of the Ti film increases. This characteristic varies depending on the processing temperature (400 ° C., 450 ° C.), but the tendency is the same. FIG. 15 shows that the TiN / Ti laminated cap has a thickness of 20n to further support the result of FIG.
This is a comparison of the EM resistance when the thickness of Ti is changed while fixing the thickness to m, and when the thickness of the TiN single-layer cap is changed.

As is clear from the above, in the TiN / Ti laminated cap, as the thickness of Ti increases, E
It can be seen that the M resistance is significantly improved. FIG. 18 shows a more detailed comparison of the EM resistance between the TiN / Ti laminate and the TiN single-layer cap. The EM stress was applied to the wiring having the TiN cap and the TiN / Ti laminate cap. This is a comparison of the change in wiring resistance during the operation.

In any of the cap structures, a breakage has occurred after an increase in the wiring resistance and a slight change in the resistance are observed. However, it can be seen that the TiN / Ti cap has a slower rate of increase in resistance with respect to the application time, and does not break until the resistance increases by about 10%. In FIG. 13, an anti-reflection film made of a laminated film of a titanium thin film and a titanium nitride thin film is used as the upper layer of each of the first wiring layer and the second wiring layer. 75%, which is functionally inferior to that of the titanium nitride thin film alone.

FIG. 19 shows the reflectance when TiN (20 nm) / Ti is used for the antireflection film in comparison with a single-layer TiN cap, a TiW cap, and no cap film. As a light source, a g-line, an i-line, and a KrF excimer laser were used. As is clear from the figure, TiN (2
It can be seen that when 0 nm) / Ti is used for the antireflection film, a better antireflection effect can be obtained as in the case of the TiN single-layer cap as compared with other cases.

In the third embodiment, the titanium thin film 22 is provided below the titanium nitride thin film 6 to reduce the contact resistance. Annealed for minutes and examined.
As a result, it was confirmed that even when the titanium thin film 22 was provided, no hillocks were generated as in the case of the titanium nitride thin film 6 alone.

Even if the third embodiment is applied to the second embodiment (that is, even if a technique of embedding a tungsten plug is used), there is no problem in operation and effect. The following can be said as a general term for each of the above embodiments. 1) The TiN / Ti cap structure has an antireflection effect equal to or higher than that of the TiN single layer structure.

2) When the TiN / Ti cap structure is applied to a two-layer wiring process, it is about 0.5 times larger than the TiN cap.
The contact resistance can be reduced by 5 × 10 ⁻⁸ Ω · cm ² . This is because AlN is formed at the interface in the TiN / Al-Si-Cu structure, but AlN is formed by inserting Ti.
This is because the formation can be suppressed. 3) When TiN / Ti is used for the cap, the EM life of the wiring is improved as compared with a single layer of TiN. Although the EM resistance is improved depending on the increase in the Ti film thickness and the sintering temperature, the EM resistance has a substantially positive correlation with the film thickness of the AlTi alloy layer after the sintering.

4) In the TiN / Ti cap structure, Ti
That the migration of Al atoms at the cap / Al-Si-Cu interface is suppressed as compared with the N single-layer cap;
The 1Ti alloy layer not only functions as an effective bypass layer than TiN, but also has an excellent EM resistance of the alloy layer itself, which contributes to an improvement in the EM resistance of the laminated wiring. It should be noted that the present invention is not limited to the above embodiments, and may be implemented as follows.

The sputtering method may be a method such as magnetron sputtering, diode sputtering, high frequency sputtering, quadrupole sputtering, or the like. As a method of the sputter etching, a reactive ion beam etching (RIBE, also called reactive ion milling) using a reactive gas (for example, CCl ₄ or SF ₆ ) may be used instead of using an inert gas.

The silicon oxide film may be formed by a method other than the CVD method (a PVD method such as a sputtering method or a vapor deposition method, or an oxidation method). The silicon oxide film may be replaced with another insulating film (various silicate glass, alumina, silicon nitride film, titanium oxide film, etc.).

The tungsten plug may be replaced with a plug made of another metal (aluminum, nickel, copper, etc.).

[0070]

According to the method of manufacturing a semiconductor device of the present invention, when forming the second to fourth titanium nitride films,
The second to fourth titanium films formed under each are buffered.
Since it works as an active layer, it can be used in a nitrogen atmosphere, which is a reactive gas.
The surface of aluminum under the second and fourth titanium films is further
Can be prevented. Also, the second titanium nitride
Before forming the film, be sure to form the second titanium film and the third titanium film.
Before forming a titanium nitride film, be sure to form a third titanium film.
Therefore, the contact resistance between the first layer wiring and the second layer wiring is
It is greatly reduced.

Further, by providing a cap metal having a laminated structure composed of a titanium film and a titanium nitride film on the wiring layer, an excellent anti-reflection film corresponding to the thickness of the Ti film can be maintained while maintaining the function as an antireflection film. Electromigration resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view illustrating a manufacturing process of a semiconductor device according to a second embodiment of the present invention;

FIG. 3 is a longitudinal sectional view of a semiconductor device according to a second embodiment.

FIG. 4 is a measurement diagram showing the effect of the first embodiment.

FIG. 5 is a measurement diagram showing a result of analyzing a contact interface between aluminum thin films by XPS.

FIG. 6 is a measurement diagram showing a result of analyzing a contact interface between an aluminum thin film and a titanium nitride thin film by XPS.

FIG. 7 is a longitudinal sectional view illustrating a manufacturing process of the semiconductor device of the first embodiment, the second embodiment, and the conventional example.

FIG. 8 is a longitudinal sectional view showing a manufacturing process of the semiconductor device of the first embodiment, the second embodiment, and the conventional example.

FIG. 9 is a longitudinal sectional view of a conventional semiconductor device.

FIG. 10 is a longitudinal sectional view showing a manufacturing process of another conventional semiconductor device.

FIG. 11 is a longitudinal sectional view of another conventional semiconductor device.

FIG. 12 is a characteristic diagram obtained by measuring the contact resistance of the example of the present invention and the conventional example.

FIG. 13 is a longitudinal sectional view of a semiconductor device according to a third embodiment.

FIG. 14 is a diagram showing a relationship between a Ti film thickness of a TiN / Ti film as a cap film and EM resistance.

FIG. 15 is a diagram comparing the difference in EM resistance between the TiN / Ti laminated cap and the TiN single-layer cap.

FIG. 16 is a diagram comparing the difference in contact resistance between a TiN / Ti laminated cap and a TiN single-layer cap.

FIG. 17 is a diagram showing an evaluation of EM resistance of a TiN / Ti laminated cap and a TiN single-layer cap.

FIG. 18 is a diagram comparing a change in wiring resistance during application of EM stress for a wiring having a TiN / Ti laminated cap and a TiN single-layer cap.

FIG. 19 is a comparison diagram showing an effect of prevention when TiN / Ti is used for an antireflection film.

[Explanation of symbols]

 Reference Signs List 5 Aluminum alloy thin film as first wiring layer 7 Silicon oxide film as interlayer insulating film 8 Contact hole 9 Titanium nitride thin film 10 Aluminum alloy thin film as second wiring layer 21, 22, 23 Titanium thin film

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yasuhiko Yamashita 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-4-332152 (JP, A) JP-A-4-18760 (JP, A) JP-A-5-190551 (JP, A) JP-A-63-205951 (JP, A) JP-A-2-239665 (JP, A) JP-A-3-239365 (JP) JP-A-4-179148 (JP, A) JP-A-3-131032 (JP, A) JP-A-5-74951 (JP, A) JP-A-5-102151 (JP, A) JP-A-64-77122 (JP, A) JP-A-1-235334 (JP, A) JP-A-3-16132 (JP, A) JP-A-3-230573 (JP, A) A) JP-A-5-94990 (JP, A) JP-A-5-190551 (JP, A) JP-A-6-268807 (J P, A) JP-A-6-45332 (JP, A) JP-A-5-109903 (JP, A) JP-A-6-21055 (JP, A) JP-A-1-91438 (JP, A) JP-A-4-311058 (JP, A) JP-A-4-278564 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/768 H01L 21/28 301 H01L 21/316 H01L 21/3205 H01L 21/3213

Claims (2)

(57) [Claims] 1. A first barrier metal having a first titanium nitride film laminated thereon is formed on a first titanium film, a first aluminum film or an aluminum alloy film is formed thereon, and a second titanium film is formed thereon. A first step of forming a first cap metal on which a second titanium nitride film is laminated, a second step of forming an interlayer insulating film on the first cap metal, A third step of forming a contact hole, and a fourth step of sputter etching the inside of the contact hole.
And steps, a fifth step of forming a third titanium film within the contact and the interlayer insulating film holes, the forming the third titanium nitride film on the third titanium film
Step 6, a seventh step of forming a second aluminum film or an aluminum alloy film on the third titanium nitride film, and a step of forming a fourth titanium film on the second aluminum film or the aluminum alloy film. An eighth step of forming a second cap metal having a fourth titanium nitride film laminated thereon. 2. A first barrier metal in which a first titanium nitride film is laminated on a first titanium film, a first aluminum film or an aluminum alloy film is formed thereon, and a second titanium film is formed thereon. A first step of forming a first cap metal on which a second titanium nitride film is laminated, a second step of forming an interlayer insulating film on the first cap metal, A third step of forming a contact hole, and a fourth step of sputter etching the inside of the contact hole.
And steps, a fifth step of forming a third titanium film within the contact and the interlayer insulating film holes, the forming the third titanium nitride film on the third titanium film
A step of embedding a metal plug in the contact hole ;
An eighth step of forming a second aluminum film or an aluminum alloy film on the metal plug and the third titanium nitride film;
And degree, on the second aluminum film or aluminum alloy film, and a ninth step of forming a second cap metal which is fourth titanium nitride film stacked on the fourth titanium film, that sequentially performed A method for manufacturing a semiconductor device, comprising: