JPH11317454A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of a metal wiring by the fluorine contained in a fluorine-containing silicon oxide film, and to improve the close contact state between the metal wiring and an interlayer insulating film, in spite of the interposition of the interlayer insulating film having a fluorine- containing silicon oxide film between the lower layer of metal wiring and the upper layer of metal wiring. SOLUTION: A lower layer of metal wiring 12, consisting of a first titanium film 12a, a first aluminum alloy film 12b and a first titanium nitride film 12c, is formed on the insulating film 11 on a semiconductor substrate 10. The first silicon rich oxide film 13, a fluorine-containing silicon oxide film 14, a second silicon rich oxide film 15 and a silicon oxide film 16 are formed on the lower layer of metal wiring 12. An upper layer of a metal wiring 17, consisting of a second titanium film 17a, a second aluminum alloy film 17b and a second titanium nitride film 17c, is formed above the silicon oxide film 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device, and more particularly to a semiconductor device having a fluorine-containing insulating film made of a fluorine-doped insulating film between metal wirings, and a method of manufacturing the semiconductor device.

[0002]

2. Description of the Related Art A semiconductor device having a fluorine-containing insulating film made of an insulating film doped with fluorine between metal wirings will be described below with reference to FIG.

[0003] As shown in FIG. 9, an insulating film 2 made of a silicon oxide film is formed on a semiconductor substrate 1. On the insulating film 2, a first titanium film 3a sequentially laminated,
A lower metal wiring 3 composed of a first aluminum alloy film 3b and a first titanium nitride film 3c is formed, and a silicon oxide film is formed between the lower metal wirings 3 and on the lower metal wiring 3. A fluorine-containing silicon oxide film 4 is formed by doping the film with fluorine.

A normal silicon oxide film 5 is formed on the fluorine-containing silicon oxide film 4, and a second titanium film 6 a and a second aluminum alloy are sequentially stacked on the silicon oxide film 5. An upper metal wiring 6 composed of the film 6b and the second titanium nitride film 6c is formed.

[0005]

The fluorine-containing silicon oxide film in which the silicon oxide film is doped with fluorine has a lower relative dielectric constant than a normal silicon oxide film in which fluorine is not doped. When an interlayer insulating film having a fluorine-containing silicon oxide film 4 is formed between the metal wirings 3 and on the lower metal wiring 3, the parasitic capacitance between the lower metal wirings 3 and the lower metal wiring 3 Since the parasitic capacitance between the metal wiring 6 and the upper layer metal wiring 6 is reduced and the signal delay is reduced, it is possible to use a signal having a higher frequency.

However, if the fluorine-containing silicon oxide film 4 is interposed between the lower metal wiring 3 and the upper metal wiring 6, the fluorine contained in the fluorine-containing silicon oxide film 4 will be oxidized in a subsequent heat treatment step. A phenomenon of diffusion into the film 5 (auto doping phenomenon) occurs. When fluorine diffuses into the silicon oxide film 5, the upper metal wiring 6
The deteriorated layer is formed at the interface between the second titanium film 6a and the silicon oxide film 5 in the second titanium film 6a, so that the adhesion between the upper metal wiring 6 and the silicon oxide film 5 is reduced, and the reliability of the semiconductor device is reduced. The problem that the performance is reduced occurs.

In view of the foregoing, the present invention provides a fluorine-containing silicon oxide film despite the presence of a fluorine-containing silicon oxide film between lower metal wires and between a lower metal wire and an upper metal wire. It is an object of the present invention to prevent the fluorine contained in the metal from deteriorating the metal wiring and improve the adhesion between the upper metal wiring and the interlayer insulating film.

[0008]

In order to achieve the above-mentioned object, a semiconductor device according to the present invention is provided between a lower metal wiring formed on a semiconductor substrate and a lower metal wiring formed on the semiconductor substrate. A first fluorine-containing insulating film formed of a fluorine-doped insulating film, an interlayer insulating film formed on a lower metal wiring and the first fluorine-containing insulating film, and a first fluorine-containing insulating film formed on the first fluorine-containing insulating film. A second fluorine-containing insulating film made of a fluorine-doped insulating film; and a silicon-rich insulating film having a silicon content larger than the stoichiometric composition. And

According to the semiconductor device of the present invention, the first fluorine-containing silicon insulating film is formed between the lower metal wires, and the second fluorine-containing silicon insulating film is formed between the lower metal wire and the upper metal wire. Since the fluorine-containing silicon insulating film is interposed, the parasitic capacitance between the lower metal wirings and the parasitic capacitance between the lower metal wiring and the upper metal wiring are reduced, so that the signal delay is reduced.

Further, since the interlayer insulating film has a silicon-rich insulating film in which the silicon content is larger than the stoichiometric composition, the first fluorine-containing silicon insulating film or the first When fluorine atoms contained in the fluorine-containing silicon insulating film of No. 2 are about to diffuse, the fluorine atoms are trapped by silicon atoms contained in the silicon-rich insulating film and having excess bonds, and do not pass through the silicon-rich insulating film. Therefore, it does not reach the upper metal wiring.

When the silicon-rich insulating film is formed above the second fluorine-containing insulating film, the silicon-rich insulating film is formed on the first fluorine-containing insulating film and the second fluorine-containing insulating film. Fluorine atoms contained therein are prevented from reaching the upper metal wiring, and a silicon-rich insulating film is formed.
When formed below the fluorine-containing insulating film,
The silicon-rich insulating film prevents the fluorine atoms contained in the first fluorine-containing insulating film from reaching the upper metal wiring and the fluorine atoms contained in the second fluorine-containing insulating film from reaching the lower metal wiring. Block.

In the semiconductor device of the present invention, the silicon-rich insulating film is formed on the first silicon-rich insulating film formed below the second fluorine-containing insulating film and on the second fluorine-containing insulating film. Preferably, the second silicon-rich insulating film is formed.

In the semiconductor device of the present invention, the silicon-rich insulating film is preferably a silicon-rich oxide film having a silicon content larger than the stoichiometric composition.

In this case, the refractive index of the silicon-rich oxide film is preferably 1.48 or more.

In the semiconductor device of the present invention, the silicon-rich insulating film is preferably a silicon-rich nitride film having a silicon content larger than the stoichiometric composition.

In this case, the refractive index of the silicon-rich nitride film is preferably 2.05 or more.

In the semiconductor device of the present invention, it is preferable that the first fluorine-containing insulating film and the second fluorine-containing insulating film are fluorine-containing silicon oxide films in which a silicon oxide film is doped with fluorine.

The method of manufacturing a semiconductor device according to the present invention is characterized in that a first fluorine-containing insulating film interposed between lower metal wires and an insulating film doped with fluorine is provided on the semiconductor substrate. Forming an inter-layer insulating film on the lower metal wiring and the first fluorine-containing insulating film; and forming an upper metal wiring on the inter-layer insulating film. The step of forming an interlayer insulating film includes the step of forming a second fluorine-containing insulating film made of a fluorine-doped insulating film and the step of forming a silicon-rich insulating film in which the silicon content is greater than the stoichiometric composition. Forming.

In the method of manufacturing a semiconductor device according to the present invention,
The step of forming an interlayer insulating film includes a step of forming a first silicon-rich insulating film on a lower metal wiring and a step of forming a second fluorine-containing insulating film on the first silicon-rich insulating film And a step of forming a second silicon-rich insulating film on the second fluorine-containing insulating film.

In the method of manufacturing a semiconductor device according to the present invention,
The silicon-rich insulating film is preferably a silicon-rich oxide film having a silicon content higher than the stoichiometric composition.

In the method of manufacturing a semiconductor device according to the present invention,
The silicon-rich insulating film is preferably a silicon-rich nitride film in which the content of silicon is greater than the stoichiometric composition.

In the method for manufacturing a semiconductor device according to the present invention,
The first fluorine-containing insulating film and the second fluorine-containing insulating film are preferably a fluorine-containing silicon oxide film in which a silicon oxide film is doped with fluorine.

In this case, the fluorine-containing silicon oxide film is
It is preferable to deposit by a plasma CVD method at a temperature of 415 ° C. to 460 ° C.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A semiconductor device according to a first embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a cross-sectional structure of the semiconductor device according to the first embodiment. As shown in FIG. 1, an insulating film 11 made of a silicon oxide film is formed on a semiconductor substrate 10. On the insulating film 11, a first titanium film 12a having a thickness of, for example, 50 nm, a first aluminum alloy film 12b having a thickness of, for example, 500 nm, and a thickness of, for example, 50 nm are sequentially laminated. A lower metal wiring 12 made of the first titanium nitride film 12c is formed. In addition, as the first aluminum alloy film 12b, in order to prevent electromigration, an alloy containing copper in aluminum (Al-0.5 at% C
u) is preferred.

The silicon content is larger than the stoichiometric composition, for example, 20 n so as to cover the lower metal wiring 12.
A first silicon-rich oxide film 13 having a thickness of m is formed, and on the first silicon-rich oxide film 13,
A fluorine-containing silicon oxide film 14 in which fluorine is doped into the silicon oxide film (the fluorine concentration is, for example, 5.0 at%) is formed. In this case, the fluorine-containing silicon oxide film 14 is formed both between the lower metal wires 12 and above the lower metal wire 12, and the lower metal wire 1 in the fluorine-containing silicon oxide film 14 is formed.
The film thickness of the upper part of 2 is preferably, for example, about 600 nm. On the fluorine-containing silicon oxide film 14, a second silicon-rich oxide film 15 having a thickness of, for example, 20 nm, in which the silicon content is larger than the stoichiometric composition, is formed. Oxide film 15
Is undoped with fluorine, for example, 400 n
A silicon oxide film 16 having a thickness of m is formed. As described above, the first silicon-rich oxide film 13,
The fluorine-containing silicon oxide film 14, the second silicon-rich oxide film 15, and the silicon oxide film 16 form an interlayer insulating film.

On the silicon oxide film 16, the second titanium film 1 having a thickness of, for example, 50 nm, which is sequentially laminated.
7a, a second aluminum alloy film 17b having a thickness of, for example, 500 nm and an upper metal wiring 17 composed of a second titanium nitride film 17c having a thickness of, for example, 50 nm are formed. The second aluminum alloy film 17b
Also, in order to prevent electromigration, alloys containing copper in aluminum (Al-0.5 at% C
u) is preferred.

The first titanium film 12a and the second titanium film 17a have a function of reducing the contact resistance between the metal wiring and the contact (tungsten plug), and the first titanium film 12c and the second titanium film The film 17c has a function as an antireflection film when a metal film is patterned to form a metal wiring, and the silicon oxide film 16 improves adhesion between the fluorine-containing silicon oxide film 14 and the upper metal wiring 17. Has a function.

In the first embodiment, the first silicon-rich oxide film 13 is formed below the fluorine-containing silicon oxide film 14, and the second silicon-rich oxide film 13 is formed above the fluorine-containing silicon oxide film 14. Since oxide film 15 is formed, in a heat treatment step performed later,
Fluorine atoms contained in the fluorine-containing silicon oxide film 14 tend to diffuse downward and upward, but the first silicon-rich oxide film 13 and the second silicon-rich oxide film 15 have excess bonds ( Since there are many silicon atoms (having dangling bonds), the fluorine atoms are trapped by the remaining silicon atoms contained in the first silicon-rich oxide film 13 and the second silicon-rich oxide film 15 that have excess bonds. . For this reason, the fluorine atoms contained in the fluorine-containing silicon oxide film 14 hardly reach the lower metal wiring 12 and the upper metal wiring 17, so that the fluorine atoms in the lower metal wiring 12 and the upper metal wiring 17 may not reach the interlayer insulating film. No deteriorated layer is formed at the interface, whereby the adhesion between the lower metal wiring 12 and the upper metal wiring 17 and the interlayer insulating film is improved.

Here, the first silicon-rich oxide film 13
Then, the amount of silicon contained in the second silicon-rich oxide film 15 will be discussed. At% of Si in a silicon oxide film (SiO ₂ ) having a stoichiometric composition is about 33.
The at% of Si contained in the first silicon-rich oxide film 13 and the second silicon-rich oxide film 15 is about 35.0% or more, for example, about 35.0% (= 1/3). About 36.2% is preferable. The reason is at% of Si
Is about 35.0% or more, the fluorine concentration becomes, for example, 5.0.
This is because it is possible to reliably prevent the passage of fluorine atoms contained in the fluorine-containing silicon oxide film 14 of 0 at%.

In measuring the concentration of silicon contained in the silicon oxide film, the refractive index is often used as a barometer of the concentration of silicon contained in the silicon oxide film. The concentration of silicon is higher. For example, at% of Si is 3
When it is 5.0%, the refractive index of the silicon oxide film is 1.48. When the at% of Si is 36.2%, the refractive index of the silicon oxide film is 1.50. Therefore, when the refractive index of the silicon-rich oxide film is 1.48 or more, the at% of Si contained in the silicon-rich oxide film becomes 35.0% or more, so that the fluorine atom contained in the fluorine-containing silicon oxide film has Passage can be reliably prevented. (First Manufacturing Method) Hereinafter, a first manufacturing method of a semiconductor device according to the first embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

First, as shown in FIG. 2A, after forming a trench in an element isolation region of a semiconductor substrate 100 made of silicon, a silicon oxide film is buried in the trench by, for example, a CVD method to form an element isolation insulating film. 101 is formed.

Next, as shown in FIG. 2B, a transistor element 1 having an impurity diffusion region, a gate insulating film, a gate electrode, and sidewalls on a semiconductor substrate 100 is formed.
02 is formed. In this case, the transistor element 102 located at the center in FIG.
1 and before and after the semiconductor substrate 100.
Thereafter, as shown in FIG. 2C, the insulating film 10 made of a silicon oxide film is formed over the entire surface of the semiconductor substrate 100.
Form 3

Next, as shown in FIG.
For example, tungsten is buried in the contact hole formed in the first contact 104 by the CVD method.
Is formed, a first titanium film 105a having a thickness of, for example, 50 nm, for example, 500 n
The first aluminum alloy film 105b having a thickness of 50 m and the first titanium nitride film 1 having a thickness of, for example, 50 nm
After sequentially laminating the first titanium films 105c,
a, patterning the first aluminum alloy film 105b and the first titanium nitride film 105c to form a lower metal interconnection 1
05 is formed.

Next, a plasma CVD method using a mixed gas of SiH ₄ gas, O ₂ gas, and Ar gas is performed so that the silicon content is lower than the stoichiometric composition so as to cover the lower metal wiring 105. The first silicon-rich oxide film 106 having a large film thickness of, for example, 20 nm (refractive index: 1.
50) is deposited.

Next, for example, at a temperature of 380 ° C.
By performing a plasma CVD method using a mixed gas of SiH ₄ gas, O ₂ gas, SiF ₄ gas, and Ar gas, on the first silicon-rich oxide film 106, the silicon oxide film is doped with fluorine and the fluorine concentration is reduced. For example, the fluorine-containing silicon oxide film 107 having a relative dielectric constant of 5.0 at% (3.
6) is deposited.

Next, a plasma CVD method using a mixed gas of SiH ₄ gas, O ₂ gas and Ar gas is performed, and the silicon content on the fluorine-containing silicon oxide film 107 becomes smaller than the stoichiometric logical composition. The second silicon-rich oxide film 108 having a large thickness of, for example, 20 nm (refractive index:
1.50).

Next, a plasma CVD method using a mixed gas of SiH ₄ gas, N ₂ O gas and N ₂ gas is performed,
On the second silicon-rich oxide film 108, for example, 20
After depositing a silicon oxide film 109 having a thickness of 00 nm (refractive index: 1.46), the silicon oxide film 109
Is polished by, for example, a CMP method so that the entire thickness becomes about 1000 nm, and the first silicon-rich oxide film 1 is polished.
06, a fluorine-containing silicon oxide film 107, a second silicon-rich oxide film 108, and a silicon oxide film 109, forming an interlayer insulating film having a flat surface.

Next, as shown in FIG. 3B, a second contact 110 is formed by burying tungsten in a contact hole formed in the interlayer insulating film by, for example, a CVD method, and then a second contact 110 is formed on the silicon oxide film 109. To, for example, 50
second titanium film 111a having a thickness of 5 nm, for example, 5 nm.
Second aluminum alloy film 11 having a thickness of 00 nm
1b and a second titanium nitride film 111c having a thickness of, for example, 50 nm, are sequentially laminated, and then, the second titanium film 111a, the second aluminum alloy film 111b, and the second
By patterning the titanium nitride film 111c to form the upper metal wiring 111, the semiconductor device according to the first embodiment is obtained. (Second Manufacturing Method) Hereinafter, a second manufacturing method of the semiconductor device according to the first embodiment of the present invention will be described.

The second manufacturing method has a feature in the method of depositing the fluorine-containing silicon oxide film 107, and the other steps are the same as those of the first manufacturing method. Only the deposition method of 107 will be described.

In the second manufacturing method, the temperature ranges from 415.degree.
At a temperature of 60 ° C., SiH ₄ gas, O ₂ gas and S
Plasma C using a mixed gas of iF ₄ gas and Ar gas
By performing the VD method, a fluorine-containing silicon oxide film 107 in which fluorine is doped into the silicon oxide film and the fluorine concentration is, for example, 5.0 at% is deposited. Hereinafter, plasma CV
The reason for setting the temperature range of the method D to 415 ° C. to 460 ° C. will be described.

FIGS. 4A to 4C show the bonding state of Si atoms, O atoms and F atoms in the fluorine-containing silicon oxide film 107 deposited by the plasma CVD method. FIG. 4A shows that adjacent Si atoms have O atoms and F atoms.
FIG. 4B shows a state in which atoms are alternately bonded to each other, FIG. 4B shows a state in which F atoms are bonded to adjacent Si atoms via O atoms, and FIG. This shows a state in which F atoms are directly bonded. As shown in FIG. 4A, when O atoms and F atoms are alternately bonded to Si atoms, the bonding force between the F atoms and the Si atoms is large. On the other hand, as shown in FIG. 4B, when the F atom is bonded to the Si atom via the O atom, the bond between the F atom and the O atom is easily broken. As shown in c), it is known that when an F atom is bonded to an adjacent Si atom, the bond between the Si atom and the F atom is easily broken.

When we performed the plasma CVD method at various temperatures, when the plasma CVD method was performed at a temperature of 415 ° C. or more, the coupling state shown in FIG. ) And (c) decrease, and plasma CVD at a temperature of 410 ° C. or less.
It has been found that when the method is performed, the bonding state shown in FIG. 4 (b) or FIG. 4 (c) increases. In this case, the plasma C
It was also found that the higher the temperature of the VD method, the more the bonding state shown in FIG.

On the other hand, the temperature of the plasma CVD method is 460 ° C.
Is exceeded, the first aluminum alloy film 105b constituting the lower metal wiring 105 is easily melted, and the cross-sectional shape of the lower metal wiring 105 is disturbed.

Therefore, the temperature range of the plasma CVD method is preferably 415 ° C. to 460 ° C.

FIG. 5 shows an interlayer insulating film obtained by the conventional method (conventional example), an interlayer insulating film (ex. 1) obtained by the first manufacturing method, and an interlayer insulating film obtained by the second manufacturing method. 10 shows a change in the fluorine concentration in the insulating film (ex. 2) from the surface to the depth direction. Incidentally, FIG. 5 is a measurement data obtained by the secondary ion mass spectrometry measurement method (SIMS), SiO 2 (5 ) (16) indicates the area of the silicon oxide film which fluorine is not doped, SiO ₂ (15) indicates a region of the silicon-rich oxide film, and SiOF (4) (14)
Indicates a region of the fluorine-containing silicon oxide film.

As shown in FIG. 5, according to the first embodiment (ex. 1 and ex. 2), the fluorine concentration in the fluorine-containing silicon oxide film is higher and the depth from the surface is lower than in the conventional example. It can be seen that the concentration of fluorine in the silicon oxide film is low at the same portion, and in the first embodiment (ex. 1 and ex. 2), the fluorine concentration changes greatly in the region of the silicon-rich oxide film. You can see that. Also, ex. 1 is ex. 2, it can be seen that the concentration of fluorine in the silicon oxide film is lower at a portion having the same depth from the surface.

As described above, in the interlayer insulating film obtained by the first embodiment, the diffusion of F atoms into the silicon oxide film is smaller than that of the conventional interlayer insulating film, and the interlayer insulating film obtained by the second manufacturing method. In the interlayer insulating film to be formed, the first
It was confirmed that the diffusion of F atoms into the silicon oxide film was smaller than that of the interlayer insulating film obtained by the method of (1). (Second Embodiment) Hereinafter, a method for manufacturing a semiconductor device according to a second embodiment of the present invention will be described with reference to FIG.

FIG. 6 shows a cross-sectional structure of the semiconductor device according to the second embodiment. As shown in FIG. 6, a silicon oxide film is doped with fluorine on a semiconductor substrate 20 to have a fluorine concentration of, for example, 5%. A first fluorine-containing silicon oxide film 21 of 0.0 at% is formed. The first fluorine-containing silicon oxide film 21 has a first barrier layer 22 a made of a titanium nitride film or a tantalum nitride film and a first fluorine-containing silicon oxide film 21. Copper film 22b
Are embedded in the lower metal wiring 22 consisting of

A silicon-rich nitride film 23 having a silicon content larger than the stoichiometric composition is formed over the entire surface of the first fluorine-containing silicon oxide film 21 and the lower metal wiring 22.

On the silicon-rich nitride film 23, a second fluorine-containing silicon oxide film 2 having a silicon oxide film doped with fluorine and having a fluorine concentration of, for example, 5.0 at% is provided.
In the second fluorine-containing silicon oxide film 24, an upper metal wiring 25 made of a second barrier layer 25a made of a titanium nitride film or a tantalum nitride film and a second copper film 25b is formed. Embedded.

In the second embodiment, since silicon-rich nitride film 23 is formed below second fluorine-containing silicon oxide film 24, the second fluorine-containing silicon oxide film Even if the fluorine atoms contained in the film 24 try to diffuse downward, the fluorine atoms are trapped by the silicon atoms contained in the silicon-rich nitride film 23 and having excess bonds. Therefore, the second
Since the fluorine atoms contained in the fluorine-containing silicon oxide film 24 hardly reach the lower metal wiring 22, no deteriorated layer is formed at the interface between the lower metal wiring 22 and the interlayer insulating film. The adhesion between the metal wiring 22 and the interlayer insulating film is improved.

In particular, in the second embodiment, the silicon-rich oxide film (density: 2.3) in the first embodiment is used.
g / cm ³ ) instead of a silicon-rich nitride film (density: 2.7 g / cm ³ ) having a dense film quality.
Fluorine atoms contained in the second fluorine-containing silicon oxide film 24 hardly pass through the silicon-rich nitride film 23.

Here, the amount of silicon contained in the silicon-rich nitride film 23 will be examined. Si at% in silicon nitride film (Si ₃ N ₄ ) having stoichiometric composition
Is about 43% (= 3/7), whereas the at% of Si contained in the silicon-rich oxide film 23 is preferably about 45% or more. The reason is that when the at% of Si is about 45% or more, the fluorine concentration becomes, for example, 5.0 at%.
This is because the diffusion of fluorine atoms contained in the second fluorine-containing silicon oxide film 24 can be surely prevented.

As described above in the case of the silicon oxide film, in measuring the concentration of silicon contained in the silicon nitride film, the refractive index is often used as a barometer of the concentration of silicon contained in the silicon nitride film. When the at% of Si is 45%, the refractive index is 2.05. Therefore, the refractive index of the silicon-rich nitride film is 2.05
With the above, the at% of Si contained in the silicon-rich nitride film becomes 45% or more, so that the passage of fluorine atoms contained in the fluorine-containing silicon nitride film can be surely prevented.

The first barrier layer 22a and the second barrier layer 25a are formed such that oxygen atoms contained in the first or second fluorine-containing silicon oxide films 21 and 24 are the first or second copper film 22b. 25b or the first or second copper film 22
The first barrier layer 22a is provided to prevent copper atoms contained in the first and second fluorine-containing silicon oxide films 21 and 24 from diffusing into the first and second fluorine-containing silicon oxide films 21 and 24.
Since the second barrier layer 25a is made of a dense titanium nitride film or a tantalum nitride film, the fluorine atoms contained in the first fluorine-containing silicon oxide film 21 have the lower metal interconnection 2
This prevents diffusion of the fluorine atoms contained in the second first copper film 22b and diffusion of fluorine atoms contained in the second fluorine-containing silicon oxide film 24 into the second copper film 25b of the upper metal wiring 25. (Manufacturing Method) A method of manufacturing a semiconductor device according to the second embodiment of the present invention will be described below with reference to FIGS.

[0057] First, as shown in FIG. 7 (a), SiH ₄
By performing a plasma CVD method using a mixed gas of a gas, an O ₂ gas, a SiF ₄ gas, and an Ar gas, a silicon oxide film is doped on a silicon substrate with a fluorine concentration of, for example, 5. After depositing the first fluorine-containing silicon oxide film 201 of 0 at%, a first wiring groove 201a is formed in a wiring formation region of the first fluorine-containing silicon oxide film 201.

Next, as shown in FIG. 7B, a sputtering method using a target made of titanium or tantalum is performed in a nitrogen atmosphere to cover the entire surface of the semiconductor substrate 200 including the first wiring groove 201a. After depositing a first barrier layer 202 made of a titanium nitride film or a tantalum nitride film over the entire surface, a first copper film 203 is deposited over the entire surface of the first barrier layer 202 by a plating method.

Next, as shown in FIG.
The first barrier layer 202 and the first copper film 2 are formed by the MP method.
A portion of the semiconductor substrate 200 exposed on the surface of the semiconductor substrate 200 is removed to form a lower metal wiring 204 including a first barrier layer 202 and a first copper film 203.

Next, as shown in FIG. 8 (a), SiH ₄
By performing a plasma CVD method using a mixed gas of a gas, an NH ₃ gas, and a N ₂ gas, the silicon content becomes stoichiometric over the entire surface of the semiconductor substrate 200 including the lower metal wiring 204. A silicon-rich nitride film 205 (refractive index: 2.05) larger than the composition is deposited.

Next, SiH ₄ gas, O ₂ gas and SiF ₄
After performing a plasma CVD method using a mixed gas of a gas and an Ar gas to deposit a second fluorine-containing silicon oxide film 206 in which the silicon oxide film is doped with fluorine and has a fluorine concentration of, for example, 5.0 at%, A second wiring groove 206a is formed in a wiring formation region of the second fluorine-containing silicon oxide film 206.

Next, as shown in FIG. 8B, a sputtering method using a target made of titanium or tantalum is performed in a nitrogen atmosphere to cover the entire surface of the semiconductor substrate 200 including the second wiring groove 206a. After depositing a second barrier layer 208 made of a titanium nitride film or a tantalum nitride film over the entire surface, a second copper film 209 is deposited on the entire surface of the second barrier layer 208 by plating. afterwards,
For example, the second barrier layer 208 and the second
When a portion of the copper film 209 exposed on the surface of the second fluorine-containing silicon oxide film 206 is removed to form an upper metal wiring composed of the second barrier layer 208 and the second copper film 209, Thus, the semiconductor device according to the second embodiment shown in FIG. 6 is obtained.

In the first and second embodiments, the fluorine-containing silicon oxide film in which the silicon oxide film is doped with fluorine is used as the fluorine-containing insulating film in which fluorine is doped. Instead, a fluorine-containing silicon nitride film in which a silicon nitride film is doped with fluorine may be used.

[0064]

According to the semiconductor device of the present invention, the first
The fluorine atoms contained in the fluorine-containing silicon insulating film or the second fluorine-containing silicon insulating film are trapped by the silicon atoms that are included in the silicon-rich insulating film and have excess bonds, even if they are to be diffused. Since the fluorine atoms can hardly pass through the insulating film, the fluorine atoms do not reach the lower metal wiring or the upper metal wiring, so that the deteriorated layer is not formed at the interface between the lower metal wiring and the upper metal wiring with the interlayer insulating film. Alternatively, the adhesion between the upper metal wiring and the interlayer insulating film is improved.

Therefore, according to the semiconductor device of the present invention, the parasitic capacitance between the lower metal wires and between the lower metal wire and the upper metal wire can be reduced, and the lower or upper metal wire and the interlayer insulating film can be reduced. Therefore, a highly reliable semiconductor device can be realized.

In the semiconductor device according to the present invention, the silicon-rich insulating film may be a first silicon-rich insulating film below the second fluorine-containing insulating film and a second silicon film above the second fluorine-containing insulating film. With the rich insulating film, the fluorine atoms contained in the first fluorine-containing insulating film do not reach the upper metal wiring, and the fluorine atoms contained in the second fluorine-containing silicon insulating film are removed from the upper metal wiring and the lower metal wiring. To reach any of the metal wirings.

In the semiconductor device of the present invention, when the silicon-rich insulating film is a silicon-rich oxide film having a refractive index of 1.48 or more, it is possible to reliably prevent a situation where fluorine atoms pass through the silicon-rich oxide film. Can be.

In the semiconductor device of the present invention, when the silicon-rich insulating film is a silicon-rich nitride film having a refractive index of 2.05 or more, it is possible to reliably prevent a situation in which fluorine atoms pass through the silicon-rich nitride film. Can be.

In the semiconductor device of the present invention, when the first fluorine-containing insulating film and the second fluorine-containing insulating film are fluorine-containing silicon oxide films, the lower metal wirings and the lower metal wiring and the upper metal wiring are formed. Can be reliably reduced.

According to the method of manufacturing a semiconductor device of the present invention,
The step of forming the interlayer insulating film includes the step of forming a second fluorine-containing insulating film made of a fluorine-doped insulating film and the step of forming a silicon-rich insulating film in which the silicon content is higher than the stoichiometric composition. And forming a second fluorine-containing insulating film made of a fluorine-doped insulating film and a silicon-rich insulating film having a silicon content larger than the stoichiometric composition. can do.

In the method of manufacturing a semiconductor device according to the present invention,
When the first fluorine-containing insulating film and the second fluorine-containing insulating film are fluorine-containing silicon oxide films deposited by a plasma CVD method at a temperature of 415 ° C. to 460 ° C., they are included in the fluorine-containing silicon oxide film. Since fluorine atoms are hardly cut from silicon atoms, diffusion of fluorine atoms can be further prevented.

[Brief description of the drawings]

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

FIGS. 2A to 2C are cross-sectional views illustrating respective steps of a first method for manufacturing a semiconductor device according to the first embodiment of the present invention.

FIGS. 3A and 3B are cross-sectional views illustrating respective steps of a first method for manufacturing a semiconductor device according to the first embodiment of the present invention. FIGS.

FIGS. 4A to 4C are schematic diagrams showing a bonding state of Si atoms, O atoms, and F atoms in a fluorine-containing silicon oxide film deposited by a plasma CVD method.

FIG. 5 is a diagram showing a change in fluorine concentration from the surface to the depth direction in an interlayer insulating film obtained by a first manufacturing method and a second manufacturing method.

FIG. 6 is a sectional view of a semiconductor device according to a second embodiment of the present invention.

FIGS. 7A to 7C are cross-sectional views illustrating steps of a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIGS. 8A and 8B are cross-sectional views illustrating steps of a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 9 is a cross-sectional view of a conventional semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Semiconductor substrate 11 Insulating film 12 Lower metal wiring 12a First titanium film 12b First aluminum alloy film 12c First titanium nitride film 13 First silicon-rich oxide film 14 Fluorine-containing silicon oxide film 15 Second silicon Rich oxide film 16 Silicon oxide film 17 Upper metal wiring 17a Second titanium film 17b Second aluminum alloy film 17c Second titanium nitride film 20 Semiconductor substrate 21 First fluorine-containing silicon oxide film 22 Lower metal wiring 22a First barrier layer 22b First copper film 23 Silicon-rich nitride film 24 Second fluorine-containing silicon oxide film 25 Upper metal wiring 25a Second barrier layer 25b Second copper film 100 Semiconductor substrate 101 Element isolation insulating film Reference Signs List 102 transistor element 103 insulating film 104 first contact 105 Layer metal wiring 105a First titanium film 105b First aluminum alloy film 105c First titanium nitride film 106 First silicon-rich oxide film 107 Fluorine-containing silicon oxide film 108 Second silicon-rich oxide film 109 Silicon oxide film 110 second contact 111 upper metal wiring 111a second titanium film 111b second aluminum alloy film 111c second titanium nitride film 200 semiconductor substrate 201 first fluorine-containing silicon oxide film 201a first wiring groove 202 1st barrier layer 203 1st copper film 204 Lower metal wiring 205 Silicon rich nitride film 206 2nd fluorine containing silicon oxide film 206a 2nd wiring groove 208 2nd barrier layer 209 2nd copper film

[Procedure amendment]

[Submission date] February 16, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

[0009] According to the semiconductor device of the present invention, the second fluorocarbon between with the first fluorine-containing insulating film between the adjacent lower metal wiring is formed, the underlying metal interconnect and an upper metal wiring Since the contained insulating film is interposed, the parasitic capacitance between the lower metal wirings and the parasitic capacitance between the lower metal wiring and the upper metal wiring are reduced, so that the signal delay is reduced.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

Further, since the interlayer insulating film has a silicon-rich insulating film in which the content of silicon is greater than the stoichiometric composition, the first fluorine-containing insulating film or the second When the fluorine atoms contained in the fluorine-containing insulating film are about to diffuse, the fluorine atoms are trapped by the remaining silicon atoms contained in the silicon-rich insulating film and have excess bonds, and do not pass through the silicon-rich insulating film. It does not reach the upper metal wiring.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0047

[Correction method] Change

[Correction contents]

As shown in FIG. 5, according to the first embodiment (ex. 1 and ex. 2), the fluorine concentration in the fluorine-containing silicon oxide film is higher and the depth from the surface is lower than in the conventional example. It can be seen that the concentration of fluorine in the silicon oxide film is low at the same portion, and in the first embodiment (ex. 1 and ex. 2), the fluorine concentration changes greatly in the region of the silicon-rich oxide film. You can see that. Also, ex. 2 is ex. It can be seen that the concentration of fluorine in the silicon oxide film is lower at a portion having the same depth from the surface as compared with the case of No. 1 .

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0064

[Correction method] Change

[Correction contents]

[0064]

According to the semiconductor device of the present invention, the first
The fluorine atoms contained in the fluorine-containing insulating film or the second fluorine-containing insulating film are trapped by the silicon atoms contained in the silicon-rich insulating film and having excess bonds, even when trying to diffuse, and the silicon-rich insulating film , Fluorine atoms do not reach the lower or upper metal wiring, so that a deteriorated layer is not formed at the interface between the lower or upper metal wiring and the interlayer insulating film. The adhesion between the metal wiring and the interlayer insulating film is improved.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0066

[Correction method] Change

[Correction contents]

In the semiconductor device according to the present invention, the silicon-rich insulating film may be a first silicon-rich insulating film below the second fluorine-containing insulating film and a second silicon film above the second fluorine-containing insulating film. With the rich insulating film, the fluorine atoms contained in the first fluorine-containing insulating film do not reach the upper metal wiring, and the fluorine atoms contained in the second fluorine-containing insulating film are removed from the upper metal wiring and the lower metal wiring. It does not reach any of the metal wirings.

Claims (13)

[Claims] A first metal interconnection formed between the lower metal interconnection formed on the semiconductor substrate and the lower metal interconnection formed on the semiconductor substrate, the first metal interconnection comprising a fluorine-doped insulating film;
A fluorine-containing insulating film, an interlayer insulating film formed on the lower metal wiring and the first fluorine-containing insulating film, and an upper metal wiring formed on the interlayer insulating film, The interlayer insulating film has a second fluorine-containing insulating film made of a fluorine-doped insulating film and a silicon-rich insulating film having a silicon content larger than the stoichiometric composition. Semiconductor device. 2. The semiconductor device according to claim 2, wherein the silicon-rich insulating film is
A first silicon-rich insulating film formed below the fluorine-containing insulating film, and a second silicon-rich insulating film formed above the second fluorine-containing insulating film. The semiconductor device according to claim 1. 3. The semiconductor device according to claim 1, wherein the silicon-rich insulating film is a silicon-rich oxide film having a silicon content higher than a stoichiometric composition. 4. The semiconductor device according to claim 3, wherein the silicon-rich oxide film has a refractive index of 1.48 or more. 5. The semiconductor device according to claim 1, wherein the silicon-rich insulating film is a silicon-rich nitride film having a silicon content larger than a stoichiometric composition. 6. The semiconductor device according to claim 5, wherein a refractive index of said silicon-rich nitride film is 2.05 or more. 7. The method according to claim 1, wherein the first fluorine-containing insulating film and the second fluorine-containing insulating film are a fluorine-containing silicon oxide film in which a silicon oxide film is doped with fluorine. Semiconductor device. 8. A lower metal wiring on a semiconductor substrate;
Forming a first fluorine-containing insulating film comprising an insulating film doped with fluorine interposed between the lower metal wirings; and forming a first fluorine-containing insulating film on the lower metal wiring and the first fluorine-containing insulating film. A step of forming an interlayer insulating film; and a step of forming an upper metal wiring on the interlayer insulating film. The step of forming the interlayer insulating film comprises a second step of forming a fluorine-doped insulating film. A method for manufacturing a semiconductor device, comprising: a step of forming a fluorine-containing insulating film; and a step of forming a silicon-rich insulating film having a silicon content higher than a stoichiometric composition. 9. The step of forming the interlayer insulating film includes: forming a first silicon-rich insulating film on the lower metal wiring; and forming the second silicon-rich insulating film on the first silicon-rich insulating film. 9. The method according to claim 8, further comprising the steps of: forming a fluorine-containing insulating film; and forming a second silicon-rich insulating film on the second fluorine-containing insulating film. Production method. 10. The method according to claim 8, wherein the silicon-rich insulating film is a silicon-rich oxide film having a silicon content greater than a stoichiometric composition. 11. The method according to claim 8, wherein the silicon-rich insulating film is a silicon-rich nitride film having a silicon content larger than a stoichiometric composition. 12. The first fluorine-containing insulating film and the second fluorine-containing insulating film.
9. The method according to claim 8, wherein the fluorine-containing insulating film is a fluorine-containing silicon oxide film in which a silicon oxide film is doped with fluorine. 13. The fluorine-containing silicon oxide film according to claim 4, wherein
The method according to claim 12, wherein the deposition is performed by a plasma CVD method at a temperature of 15 ° C. to 460 ° C.