JP2001176816A - Device and method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device and its manufacturing method which an suppress an increase in the contact resistance of an Al alloy wire in a connection hole, by preventing products of reaction on Al from being formed, when etching for forming the connection hole in an interlayer insulating film is carried out. SOLUTION: This manufacturing method for a semiconductor device has a stage for forming an amorphous TiOX film 18 on a 1st Al-Cu alloy film 15, a stage for forming a 1st Al alloy wire by patterning the amorphous TiOX film 18 and 1st Al-C alloy film 15, a stage for forming a 2nd interlayer insulating film 19 on the 1st Al alloy wire 15, a stage for forming a via hole 19a positioned on the 1st Al alloy wire 15 in the 2nd interlayer insulating film 19, a stage for forming a via hole 19a positioned on the 1st Al alloy wire 15 in the interlayer insulating film 19 by etching the interlayer insulating film 19, and a stage for forming a 2nd Al alloy wire in the via hole 19a and on the interlayer insulating film 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device capable of suppressing an increase in contact resistance of an Al alloy wiring in a connection hole and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIGS. 6 and 8 are sectional views for explaining a conventional method of manufacturing a semiconductor device. FIG. 7 is a plan view of a via hole in the interlayer insulating film shown in FIG. 6 as viewed from above.

[0003] First, as shown in FIG.
01, a gate oxide film 103 is formed by a thermal oxidation method,
A gate electrode 105 is formed on the gate oxide film 103. Thereafter, ion implantation is performed using the gate electrode 105 as a mask to form diffusion layers 107 and 108 of source / drain regions on the silicon substrate 101.
Next, a first interlayer insulating film 109 is formed on the gate electrode 105 and the gate oxide film 103, and the first interlayer insulating film 1 is formed.
09, a contact hole (connection hole) 109a is formed.

Thereafter, Ti is deposited in the contact hole 109a and on the first interlayer insulating film 109 by sputtering.
A film 111 is formed, and a TiN film 113 is formed on the Ti film 111 by a sputtering method. Next, a first film is formed on the TiN film 113 and in the contact hole 109a by a sputtering method.
Al-Cu alloy film 115 is deposited. Thereafter, a TiN film 117 as an antireflection film is formed on the first Al-Cu alloy film 115 by a sputtering method. Next, this Ti
By applying a resist film (not shown) on the N film 117, exposing and developing the resist film, a resist pattern (not shown) is formed on the TiN film 117. Using this resist pattern as a mask, the TiN film 117 and the first
By etching the Al-Cu alloy film 115, the first Al alloy wiring 1 is formed on the first interlayer insulating film 109.
15 are formed.

Next, the second Al alloy wiring 115 is
Of the second interlayer insulating film 119 is deposited.
By applying a resist film thereon, exposing and developing the resist film, a resist pattern 121 is formed on the second interlayer insulating film 119. Thereafter, the second interlayer insulating film 1 is subjected to wet etching using the resist pattern 121 as a mask and then to dry etching.
19, a contact hole (connection hole) 119a is formed. Further, using the resist pattern 121 as a mask, CF
The TiN film 117 at the bottom of the via hole 119a is removed by performing dry etching with a _four- system etching gas.

After that, as shown in FIG. 8, the resist pattern 121 is peeled off, and the surface of the second interlayer insulating film 119 is cleaned (reverse sputtering). Next, Ti is formed in the via hole 119a and on the second interlayer insulating film 119 by sputtering.
A film 125 is formed, and a TiN film 127 is formed on the Ti film 125 by a sputtering method. Next, the TiN film 127
A second Al-Cu alloy film 129 is deposited on the upper portion and in the via hole 119a by a sputtering method. After this, the second A
A TiN film 131 as an antireflection film is formed on the l-Cu alloy film 129 by a sputtering method. Next, this TiN
A resist pattern (not shown) is formed on the TiN film 131 by applying a resist film (not shown) on the film 131 and exposing and developing the resist film. By etching the TiN film 131 and the second Al-Cu alloy film 129 using this resist pattern as a mask,
Second Al alloy wiring 129 is formed on second interlayer insulating film 119.
Is formed.

[0007]

In the above-described conventional method for manufacturing a semiconductor device, when dry etching is performed on the second interlayer insulating film 119 to form the connection hole 119a, the film of the interlayer insulating film 119 is formed. Since the thickness varies in some places, the TiN film 117 is etched during over-etching, and the first Al-Cu alloy film 115 is exposed to an etching atmosphere. At this time, a reaction product (eg, Al ₂ O ₃ ) 123 with Al is formed at the bottom of the connection hole 119a, and the reaction product 123 adheres to the inside of the connection hole 119a in a crown shape as shown in FIGS. I do. Then, the second Al
Before forming the Cu alloy film 129, the second interlayer insulating film 1
The surface of No. 19 is cleaned (reverse sputtering), but the reaction product 1
23 remains at the bottom of the connection hole, and as a result, the contact resistance in the connection hole 119a increases.

The present invention has been made in view of the above circumstances, and has as its object to form a reaction product with Al when etching for forming a connection hole in an interlayer insulating film. An object of the present invention is to provide a semiconductor device capable of suppressing an increase in contact resistance of an Al alloy wiring in a connection hole by preventing the same and a method for manufacturing the same.

[0009]

The method of manufacturing a semiconductor device according to the present invention SUMMARY OF THE INVENTION includes the steps of forming an amorphous TiO _X film on the Al alloy film, the amorphous TiO _X film and A
forming a first Al alloy wiring by patterning the l-alloy film, forming an interlayer insulating film on the first Al alloy wiring, and etching the interlayer insulating film to form a first Al alloy wiring. Forming a connection hole located on the Al alloy wiring in the interlayer insulating film; forming a second Al alloy wiring in the connection hole and on the interlayer insulating film;
It is characterized by having.

The interlayer insulating film is preferably a SiO ₂ film.

According to the method of manufacturing a semiconductor device described above,
Since forming the amorphous TiO _X film on the alloy film, the amorphous TiO _X film acts as an etching stopper when etching the interlayer insulating film. Therefore, at the time of this etching, the Al alloy wiring is not exposed at the bottom of the connection hole, so that a reaction product with Al can be prevented from being generated at the bottom of the connection hole. As a result, an increase in the contact resistance of the Al alloy wiring in the connection hole can be suppressed.

A method for manufacturing a semiconductor device according to the present invention
a step of introducing oxygen to the surface of the alloy film and TiN
The step of forming a film and the heat treatment of the TiN film in a nitrogen atmosphere make the TiN film a dense film and an amorphous TiO _x film at the interface between the Al alloy film and the TiN film.
A step of forming a film, the TiN film and the amorphous Ti
Forming a O _X film and the first Al alloy wiring by patterning the Al alloy film, a step of forming an interlayer insulating film on the first Al alloy wire, by etching the interlayer insulating film Forming a connection hole located on the first Al alloy wiring in the interlayer insulating film; and forming a second Al alloy wiring in the connection hole and on the interlayer insulating film. It is characterized by.

According to the method of manufacturing a semiconductor device described above,
Amorphous TiO on alloy film_XForming a film
This amorphous TiO_XFilm etch interlayer dielectric
Acts as an etching stopper when performing etching. This
At the same time, amorphous TiO _XForm TiN film on film
And then subjecting the TiN film to a heat treatment in a nitrogen atmosphere.
Makes the TiN film a dense film with good etching resistance
Therefore, this TiN film also serves as an etching stopper.
Works well. Therefore, during this etching,
Since the Al alloy wiring is not exposed at the bottom of the continuous hole, A
to prevent reaction products from being generated at the bottom of the connection hole.
Wear. In addition, by making the TiN film a dense film,
Light reflectance can be reduced. Also, TiN film and
Amorphous TiO between Al alloy film_XForm a film
Thereby, the adhesion between the TiN film and the Al alloy film is improved.
You. As a result, the TiN film may come off from the Al alloy film.
And can be suppressed.

In the method of manufacturing a semiconductor device according to the present invention, the step of introducing oxygen for forming the amorphous TiO _x film is performed by adding 450% to the Al alloy film in an oxygen atmosphere.
Preferably, a step of introducing oxygen to the surface of the Al alloy film by performing a heat treatment at a temperature of not more than ° C or a step of performing oxygen plasma treatment on the surface of the Al alloy film is preferable.

Further, in the method of manufacturing a semiconductor device according to the present invention, the dense film, the Al alloy film and the TiN
The step of forming an amorphous TiO _X film at the interface of the film
It is preferable to carry out at a temperature of 400 ° C. or more and 450 ° C. or less.

A semiconductor device according to the present invention comprises an amorphous TiO _x film formed on a first Al alloy wiring,
An interlayer insulating film formed on the Al alloy wiring, a connection hole formed on the first Al alloy wiring formed on the interlayer insulating film, and formed in the connection hole and on the interlayer insulating film. And a second Al alloy wiring.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 are sectional views showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.

First, as shown in FIG.
A gate oxide film 3 is formed thereon by a thermal oxidation method, and a gate electrode 5 is formed on the gate oxide film 3. Thereafter, impurity ions are implanted using the gate electrode 5 as a mask to form source / drain region diffusion layers 7 and 8 in the silicon substrate 1. Next, a first interlayer insulating film 9 made of a SiO ₂ film is deposited on the gate electrode 5 and the gate oxide film 3 by a CVD (Chemical Vapor Deposition) method.

Thereafter, a resist film (not shown) is applied on the first interlayer insulating film 9, and the resist film is exposed and developed to form a resist pattern (FIG. 5) on the first interlayer insulating film 9. (Not shown). Next, using this resist pattern as a mask, the interlayer insulating film 9 is wet-etched and then dry-etched to form a contact hole (connection hole) 9a in the first interlayer insulating film 9.

Next, a Ti film 11 is formed by sputtering in the contact hole 9a and on the first interlayer insulating film 9, and a TiN film 1 is formed on the Ti film 11 by sputtering.
3 is formed. Note that the Ti film 11 and the TiN film 13 function as barrier metals. Next, the first Al is formed on the TiN film 13 and in the contact hole 9a by sputtering.
-Deposit a Cu alloy film 15;

Thereafter, as shown in FIG.
By subjecting the Cu alloy film 15 to a heat treatment at 450 ° C. or lower in an O ₂ atmosphere, oxygen is introduced to the surface of the Al—Cu alloy film 15. This is the first Al—Cu alloy film 1 described later.
When the amorphous TiO _X film 18 is formed on
It becomes a factor for oxidizing Ti in the N film. The heat treatment conditions at this time include a treatment time of about 200 to 1800 seconds, O ₂
It is preferable that the oxygen concentration in the atmosphere is about 10 to 30% and the pressure is normal pressure. This amorphous TiO _X film 1
8 is a second hole for forming a via hole 19a to be described later.
Acts as an etching stopper when the interlayer insulating film 19 is etched. However, since the amorphous TiO _X film 18 is an insulating film, the thickness of the amorphous TiO _X film 18 at the bottom of the via hole 19a is set to a thickness that can be removed by cleaning the surface of the interlayer insulating film 19 by reverse sputtering, which will be described later. 5 nm or more and 30 nm
It is appropriate that the thickness is as small as possible. Specifically, the thickness of the amorphous TiO _X film 18 is 0.00
About 1 to 0.01 μm is preferable.

The method of introducing oxygen to the surface of the Al—Cu alloy film 15 is not limited to a heat treatment at 450 ° C. or lower in an O ₂ atmosphere, and other methods can be used. ₂ It is also possible to use a method of introducing oxygen using plasma, and it is also possible to introduce oxygen by exposing the first Al-Cu alloy film 15 to the atmosphere.

Next, on the Al-Cu alloy film 15 whose surface is oxidized, a T
An iN film 17 is formed. The sputtering conditions at this time are as follows: a pressure of 10 to 50 pa, an atmosphere of Ar and nitrogen, and a reactive DC.
It is preferable to use sputtering.

Thereafter, the TiN film 17 is subjected to a heat treatment in an N ₂ atmosphere. The heat treatment conditions at this time are as follows.
450 ° C., time 200-1800 seconds, N ₂ concentration 90
It is preferable to use normal pressure at a pressure of 100%. This heat treatment makes the TiN film 17 dense, and as a result,
This TiN film 17 becomes a film having good etching resistance, and the reflectance of exposure light is reduced. At the same time, amorphous TiO _X is formed by the heat treatment, and the thickness of the amorphous TiO _X film 18 is increased. Note that TiN
The film 17 functions as an anti-reflection film. However, the above TiN
The step of subjecting the film 17 to heat treatment in an N ₂ atmosphere is preferably performed, but is not always necessary.

Next, a resist film (not shown) is applied on the TiN film 17, and the resist film is exposed and developed to form a resist pattern (not shown) on the TiN film 17. Using this resist pattern as a mask, Ti
N film 17, amorphous TiO _x film 18, first Al—
By etching the Cu alloy film 15, the TiN film 13 and the Ti film 11, the first A film is formed on the first interlayer insulating film 9.
1 alloy wiring 15 is formed.

Thereafter, as shown in FIG. 3, a second interlayer insulating film 19 made of a SiO ₂ film having a thickness of about 0.5 μm is deposited on the first Al alloy wiring 15 by a CVD method. Next, a resist pattern is formed on the second interlayer insulating film 19 by applying a resist film on the second interlayer insulating film 19 and exposing and developing the resist film.

Thereafter, as shown in FIG. 4, the second interlayer insulating film 19 is formed by wet etching using the resist pattern 21 as a mask and then dry etching.
Then, a via hole (connection hole) 19a is formed. On this occasion,
Since the TiN film 17 is a dense film as described above, the etching selectivity with respect to the second interlayer insulating film 19 is increased, and as a result, acts as an etching stopper. The thickness of the TiN film 17 is such that the TiN film 17 remains even at the bottom of the shallow via hole when the plurality of via holes 19a are formed by etching. Further, even when the heat treatment step for making the TiN film 17 dense is not performed, the amorphous TiO _x film 18 sufficiently functions as an etching stopper, so that the surface of the first Al—Cu alloy film 15 is formed when the via hole 19a is formed. Will not be exposed.

The wet etching conditions are H
The treatment is performed with the F type liquid. The conditions of the dry etching are preferably such that the pressure is 2 to 50 pa and the anisotropic etching is performed by using a reactive ion etcher whose main gas is CHF ₃ and CF ₄ .

Next, the TiN film 17 in the via hole 19a is
Is removed by etching. Thereafter, as shown in FIG. 5, the resist pattern 21 is peeled off, and the surface of the second interlayer insulating film 19 is cleaned (reverse sputtering). Next, the via hole 19
a on the second interlayer insulating film 19 by sputtering.
An i film 25 is formed, and a TiN film 27 is formed on the Ti film 25 by a sputtering method. Note that the Ti film 25 and the TiN film 27 function as a barrier metal. After this,
A second Al-Cu alloy film 29 is deposited on the TiN film 27 and in the via hole 19a by a sputtering method.

Next, a TiN film 31 is formed on the second Al-Cu alloy film 29 by a sputtering method. Thereafter, a resist film (not shown) is applied on the TiN film 31, and the resist film is exposed and developed, whereby a resist pattern (not shown) is formed on the TiN film 31. Using this resist pattern as a mask, the TiN film 31 and the second A
The second Al alloy wiring 29 is formed on the second interlayer insulating film 19 by etching the l-Cu alloy film 29, the TiN film 27, and the Ti film 25.

According to the above embodiment, the first Al-C
Since forming the amorphous TiO _X film 18 on u alloy film 15 acts as an etching stopper when the amorphous TiO _X film 18 to etch the second interlayer insulating film 19 shown in FIG. Therefore, even when the thickness of the second interlayer insulating film 19 is different in some places, the Al-Cu alloy film is not exposed at the bottom of the via hole unlike the conventional method of manufacturing a semiconductor device. A
Reaction products with Al such as l ₂ O ₃ can be prevented from being generated at the bottom of the via hole. As a result, an increase in the contact resistance of the Al alloy wiring in the via hole can be suppressed, and the contact resistance can be reduced.

In this embodiment, after the TiN film 17 is formed on the Al--Cu alloy film 15, the TiN film 1
7 is subjected to a heat treatment in an N ₂ atmosphere to obtain a TiN film 1.
7 is a dense film having good etching resistance. That is, since the TiN film 17 has a higher etching selectivity with respect to the second interlayer insulating film 19 than the TiN film of the prior art,
In etching for forming a via hole 19a in the second interlayer insulating film 19, it sufficiently functions as an etching stopper. Therefore, an increase in the contact resistance of the Al alloy wiring in the via hole can be suppressed.

In the present embodiment, the reflectance of the exposure light can be made lower than that of the TiN film of the conventional semiconductor device by making the TiN film 17 dense as described above. Therefore, the anti-reflection function of the TiN film 17 can be improved, and as a result, the first Al—Cu alloy film 15
Can be accurately patterned.

In this embodiment, an amorphous TiN film is provided between the TiN film 17 and the first Al—Cu alloy film 15.
By forming the _Ox film 18, the TiN film 17 and the first
Is improved with the Al—Cu alloy film 15. For this reason, it is possible to prevent the TiN film 17 from peeling off from the first Al—Cu alloy film 15 and to prevent the antireflection function of the TiN film 17 from being lost. As a result, the first Al-
The Cu alloy film 15 can be accurately patterned,
The highly accurate first Al alloy wiring 15 can be formed.

The present invention is not limited to the above-described embodiment, but can be implemented with various modifications.

[0037]

As described above, according to the present invention, the formation of a reaction product with Al during the etching for forming a connection hole in an interlayer insulating film is prevented, whereby the inside of the connection hole is prevented. A semiconductor device capable of suppressing an increase in contact resistance of an Al alloy wiring and a method for manufacturing the same can be provided.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the present invention, showing a step subsequent to FIG. 1;

FIG. 3 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the present invention, showing a step subsequent to FIG. 2;

FIG. 4 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the embodiment of the present invention, which shows the step subsequent to FIG. 3;

FIG. 5 is a cross-sectional view illustrating the method of manufacturing the semiconductor device according to the embodiment of the present invention, which shows the step subsequent to FIG. 4;

FIG. 6 is a cross-sectional view for explaining a conventional method for manufacturing a semiconductor device.

FIG. 7 is a plan view of a via hole in the interlayer insulating film shown in FIG. 6, as viewed from above.

FIG. 8 is a cross-sectional view for explaining the conventional method of manufacturing the semiconductor device and showing a step subsequent to FIG. 6;

[Explanation of symbols]

Reference Signs List 1 silicon substrate 3 gate oxide film 5 gate electrode 7, 8 diffusion layer of source / drain region 9 first interlayer insulating film 9a contact hole (connection hole) 11 Ti film 13 TiN film 15 first Al-Cu alloy film ( (First Al alloy wiring) 17 TiN film 18 Amorphous TiO _X film 19 Second interlayer insulating film 19a Via hole (connection hole) 21 Resist pattern 25 Ti film 27 TiN film 29 Second Al-Cu alloy film (second Al alloy wiring) 31 TiN film 101 Silicon substrate 103 Gate oxide film 105 Gate electrode 107, 108 Diffusion layer of source / drain region 109 First interlayer insulating film 109a Contact hole (connection hole) 111 Ti film 113 TiN film 115 First Al-Cu alloy film (first Al alloy wiring) 117 Ti silicide film 11 9 second interlayer insulating film 119a via hole (connection hole) 121 resist pattern 123 reaction product (such as Al ₂ O ₃ ) 125 Ti film 127 TiN film 129 second Al—Cu alloy film (second Al alloy wiring) 131 TiN film

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Claims (5)

[Claims] A step of forming an amorphous TiO _x film on the Al alloy film; a step of patterning the amorphous TiO _x film and the Al alloy film to form a first Al alloy wiring; Forming a first interlayer insulating film on the alloy wiring; and etching the first interlayer insulating film by etching the interlayer insulating film.
forming a connection hole located on the alloy wiring in the interlayer insulating film; and forming a second Al alloy wiring in the connection hole and on the interlayer insulating film. A method for manufacturing a semiconductor device. 2. A step of introducing oxygen to the surface of the Al alloy film, a step of forming a TiN film thereon, and performing a heat treatment on the TiN film in a nitrogen atmosphere.
The above-mentioned TiN film is made into a dense film, and an Al alloy film and TiN
Forming an amorphous TiO _x film at the interface of the film; forming a first Al alloy wiring by patterning the TiN film, the amorphous TiO _x film and the Al alloy film; Forming an interlayer insulating film on the substrate, and etching the interlayer insulating film to form a first A
forming a connection hole located on the alloy wiring in the interlayer insulating film; and forming a second Al alloy wiring in the connection hole and on the interlayer insulating film. A method for manufacturing a semiconductor device. 3. The step of introducing oxygen to the surface of the Al alloy film, wherein the step of introducing oxygen to the surface of the Al alloy film by subjecting the Al alloy film to a heat treatment at 450 ° C. or less in an oxygen atmosphere. 3. The method for manufacturing a semiconductor device according to claim 2, further comprising the step of performing an oxygen plasma treatment on the surface of the semiconductor device. 4. The method according to claim 1, wherein said dense film is formed, and an Al alloy film and T
3. The method according to claim 2, wherein the step of forming the amorphous TiO _X film at the interface of the iN film is performed at a temperature of 400 ° C. or more and 450 ° C. or less. 5. An amorphous TiO _X film formed on a first Al alloy wiring, an interlayer insulating film formed on the first Al alloy wiring, and a first insulating film formed on the first Al alloy wiring. A connection hole located on the Al alloy wiring; and a second Al formed in the connection hole and on the interlayer insulating film.
A semiconductor device comprising: an alloy wiring;