JPH09298241A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a buried wiring in a porous interlayer insulating film in a semiconductor device. SOLUTION: A first silicon oxide film 21 is deposited on a semiconductor substrate 20 by a CVD method, and a porous film 22 is deposited on the first silicon oxide film 21. Thereafter, the porous film 22 is etched so as to form a wiring groove 22a. Next, a second silicon oxide film 23 is deposited over the entire porous film 22 by the CVD method, and the first and second silicon oxide films 21 and 23 are etched so as to form a through hole 21a in the first and second silicon oxide films 21 and 23. Next, a conductive film 24 is deposited over the entire second oxide film 23, and CMP is performed on the conductive film 24, so as to form a wiring layer of the conductive film 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having an interlayer insulating film made of a porous film and a method for manufacturing the same.

[0002]

2. Description of the Related Art Organic materials and inorganic materials have been conventionally known as materials for forming an interlayer insulating film in a semiconductor device. However, the interlayer insulating film made of an organic material has a problem that the relative dielectric constant is relatively low, but the heat resistance is poor. On the other hand, an interlayer insulating film made of an inorganic material has excellent heat resistance, but has a problem of high relative dielectric constant. Therefore, an interlayer insulating film having a low relative dielectric constant while maintaining heat resistance is desired,
As described below, a technique for forming an interlayer insulating film made of a porous film has been proposed.

FIG. 10 shows a sectional structure of a semiconductor device according to a first conventional example disclosed in Japanese Examined Patent Publication No. 7-46698. As shown in FIG. 10, the semiconductor substrate 110
A metal wiring 111 is formed on the above, and an interlayer insulating film 112 made of a porous film is formed over the entire surface of the semiconductor substrate 110 including the metal wiring 111.

FIG. 11 shows a sectional structure of a semiconductor device according to a second conventional example disclosed in Japanese Patent Publication No. 6-12790. As shown in FIG. 11, the semiconductor substrate 120
A metal wiring 121 is formed on the semiconductor substrate 120, a first SOG film 122 is formed on the entire surface of the semiconductor substrate 120 including the metal wiring 121 by a CVD method, and an organic film is formed on the first SOG film 122. System porous film 123 is formed, and the second SOG film 12 is formed on the porous film 123 by the CVD method.
4 are formed, and the first SOG film 122, the organic porous film 123, and the second SOG film 124 form an interlayer insulating film.

By the way, in the above-mentioned first and second conventional examples, since the method of forming the porous film is not particularly described, the method of forming the porous film described in the following documents is considered. did.

First, as a method for forming the first porous film,
IEEE Transactions on comp
onents, hybrids, and manufa
cturing technology, Vol. 1
5, No. 6 p. 925 (1992). That is, after forming an organic polymer film composed of a copolymer of an organic polymer precursor having high heat resistance and an organic polymer precursor having low heat resistance, heat treatment is applied to the organic polymer film to heat It is a method of forming a porous film made of an organic polymer material by decomposing an organic part having low property.

Next, as a method for forming the second porous film,
Makromol. Chem. , Macromol. S
ymp. 42/43, 303 (1991). That is, after forming a silica film containing an organic polymer from a mixed solution of a silanol sol and an organic polymer, heat treatment is applied to the silica film to thermally decompose the organic polymer, thereby forming a porous film made of an inorganic material. This is a method of forming a quality film.

[0008]

However, when the embedded wiring is formed in the interlayer insulating film made of a porous film,
There is a problem as described below. That is, if a recessed groove for a buried wiring is formed in an interlayer insulating film made of a porous film and then a wiring material is embedded in the recessed groove, the wiring material will enter the hole of the porous film. As a result, the insulating property of the interlayer insulating film made of a porous film is deteriorated, and since unevenness is formed on the side surface of the wiring layer, electromigration resistance of the wiring layer is deteriorated and electrical resistance of the semiconductor device is deteriorated. There is a problem that the stability of characteristics is impaired.

Therefore, it is difficult to form a buried wiring in the interlayer insulating film made of a porous film.

According to the first method of forming the porous film, the heat treatment of the organic polymer film is performed on the semiconductor substrate 27.
Since it needs to be held at a temperature of 5 ° C. for about 9 hours, there is a problem that it takes a very long time for the porosification treatment. On the other hand, it is possible to increase the temperature of the heat treatment to form the porous film in a short time, but if the heat treatment is performed at a temperature of 400 ° C. or higher, the decomposition reaction of the organic polymer occurs. , Not a fundamental solution.

Further, the second method for forming a porous film needs to hold the semiconductor substrate at a temperature of 600 ° C. for about 24 hours, so that it also takes a very long time. On the other hand, it is possible to increase the temperature of the heat treatment to form the porous film in a short time, but if the temperature of the heat treatment is increased, the glass component of the inorganic material is melted, and the melted glass component becomes porous. It does not become a fundamental solution because it blocks the pores of the membrane.

As described above, there is a problem that the conventional method for forming a porous film cannot be used for forming an interlayer insulating film made of a porous film in a semiconductor device manufacturing process.

In view of the above, it is a first object of the present invention to form an embedded wiring in an interlayer insulating film, and an interlayer insulating film made of a porous film is formed in a short time at low temperature and normal pressure. The second purpose is to be able to do so.

[0014]

In order to achieve the above-mentioned first object, a solution means provided by the invention of claim 1 is to provide a semiconductor device, a semiconductor substrate on which a first wiring layer is formed, and A first silicon oxide film formed on the semiconductor substrate,
A porous film formed on the first silicon oxide film, a through hole formed in the first silicon oxide film, and a wiring groove formed in the porous film and communicating with the through hole. A second silicon oxide film formed on the bottom and walls of the wiring trench, a contact made of a conductive film embedded in the through hole, and the second silicon oxide film in the wiring trench. And a second wiring layer made of a conductive film embedded inside.

According to the structure of the first aspect, the second silicon oxide film is formed on the bottom and the wall of the wiring groove formed in the porous film, and the second wiring layer is formed of the second silicon oxide film. Since the second silicon oxide film is embedded inside, that is, the second silicon oxide film is interposed between the second wiring layer and the porous film, the conductive material forming the second wiring layer is porous. It is possible to avoid the situation of entering the holes of the membrane.

According to a second aspect of the invention, in addition to the structure of the first aspect, the porous film is formed of an organic SOG film or an inorganic SOG film.

According to a third aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: a first step of depositing a first silicon oxide film on a semiconductor substrate having a first wiring layer formed thereon; A second step of depositing a porous film on the first silicon oxide film; a third step of forming a wiring groove in the porous film; and a porous film including the wiring groove. A fourth step of depositing a second silicon oxide film on the wiring so as not to fill the wiring trench, and a fifth step of forming a through hole in the second silicon oxide film and the first silicon oxide film. A step of depositing a conductive film over the entire surface of the second silicon oxide film including the through hole and the wiring trench, and a step of depositing the second silicon oxide film in the conductive film. The exposed portion is removed to remove the first conductive film. It is an arrangement and a seventh step of forming a wiring layer.

According to the structure of claim 3, after forming the wiring groove in the porous film deposited on the semiconductor substrate via the first silicon oxide film, the wiring film is formed on the porous film including the wiring groove. A second silicon oxide film is deposited, and then a conductive film is deposited to form a second wiring layer, that is, the second silicon is formed on the bottom and wall of the wiring groove formed in the porous film. Since the conductive film is deposited in the state where the oxide film is formed, it is possible to prevent the conductive material forming the second wiring layer from entering the holes of the porous film.

According to a fourth aspect of the present invention, in addition to the structure of the third aspect, the second step comprises adding a silylating agent to a silanol sol solution containing fine particles of a silanol condensate, whereby the fine particles of the silanol condensate remain. A step of chemically modifying a silanol group with a silyl group; a step of applying a silanol sol solution containing the silanol condensate fine particles chemically modified with the silyl group onto a semiconductor substrate to form a coating film; On the other hand, heat treatment is performed to thermally decompose the silyl group and to dehydrate and condense the residual silanol groups to make the coating film porous, thereby adding a configuration.

According to the structure of claim 4, a silanol sol solution containing silanol condensate fine particles chemically modified by a silyl group is applied on a semiconductor substrate to form a coating film, and then the coating film is heat-treated. And a silyl group chemically modifying the silanol condensate particles is thermally decomposed to form pores between the silanol condensate particles,
The residual silanol groups are dehydrated and condensed, and the silanol condensate fine particles are condensed so as to surround the pores.

According to a fifth aspect of the present invention, in the structure of the third aspect, the second step is to add a silylating agent to the silanol solution in the presence of an acid or an alkali, thereby adding the silanol contained in the silanol solution. Of chemically modifying the residual silanol groups of the above with a silyl group, a step of applying a silanol solution containing the silanol chemically modified with the silyl group onto a semiconductor substrate to form a coating film, and heat treating the coating film. And thermally decomposing the silyl group and dehydrating and condensing the residual silanol group to make the coating film porous.

According to the structure of claim 5, a silanol solution containing silanol chemically modified by a silyl group is applied onto a semiconductor substrate to form a coating film, and then the coating film is subjected to heat treatment. The residual silanol groups are dehydrated and condensed so as to surround the pores formed by the thermal decomposition of, and thus fine particles of silanol condensate having pores inside are formed.

The solution means taken by the invention of claim 6 is the first
An interlayer insulating film forming step of forming an interlayer insulating film made of a porous film on the semiconductor substrate having the wiring layer formed thereon, and a wiring layer forming step of forming a second wiring layer on the interlayer insulating film. The method for manufacturing a semiconductor device comprising the step of: forming the interlayer insulating film, wherein the silanol condensate particles are silylated by adding a silylating agent to a silanol sol solution containing the silanol condensate particles. A step of chemically modifying with a group, a step of applying a silanol sol solution containing the silanol condensate fine particles chemically modified with the silyl group onto a semiconductor substrate to form a coating film, and heat treating the coating film. And thermal decomposing the silyl group and dehydrating and condensing the residual silanol groups to make the coating film porous. That.

According to the structure of claim 6, similarly to the structure of claim 4, the silyl group chemically modifying the silanol condensate particles is thermally decomposed to form pores between the silanol condensate particles. The residual silanol groups are dehydrated and condensed, and the silanol condensate fine particles are condensed so as to surround the pores.

The solution means taken by the invention of claim 7 is the first
An interlayer insulating film forming step of forming an interlayer insulating film made of a porous film on the semiconductor substrate having the wiring layer formed thereon, and a wiring layer forming step of forming a second wiring layer on the interlayer insulating film. In the method for manufacturing a semiconductor device, the step of forming an interlayer insulating film comprises adding a silylating agent to a silanol solution in the presence of an acid or an alkali to obtain residual silanol groups of silanol contained in the silanol solution. Chemically modifying a silanol group with a silyl group, applying a silanol solution containing silanol chemically modified with the silyl group to form a coating film on a semiconductor substrate, and subjecting the coating film to heat treatment to The step of making the coating film porous by thermally decomposing the silyl group and dehydrating and condensing the residual silanol group.

According to the structure of claim 7, as in the structure of claim 5, since the residual silanol groups are dehydrated and condensed so as to surround the pores formed by thermal decomposition of the silyl group, silanol having pores inside is formed. Fine condensate particles are formed.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A semiconductor device and a method of manufacturing the same according to a first embodiment of the present invention will be described below with reference to FIGS.
This will be described with reference to (d).

First, as shown in FIG. 1A, a first silicon oxide film 2 having a film thickness of, for example, 500 nm is formed on a semiconductor substrate 20 made of, for example, silicon by a CVD method.
After depositing No. 1, a porous film 22 having a film thickness of, for example, 400 nm is deposited on the first silicon oxide film 21. Then, after forming a resist pattern on the porous film 22, the porous film 22 is etched using the resist pattern as a mask to form the wiring groove 22 a in the porous film 22.

Next, as shown in FIG. 1 (b), the entire surface of the porous film 22 is, for example, 20 nm by the CVD method.
A second silicon oxide film 23 having a film thickness of is deposited.

Next, as shown in FIG. 1C, after forming a resist pattern on the second silicon oxide film 23, the first silicon oxide film 21 and the second silicon oxide film 21 are formed using the resist pattern as a mask. The silicon oxide film 23 is etched to remove the first silicon oxide film 21 and the second silicon oxide film 21.
A through hole 21a is formed in the silicon oxide film 23 of FIG.

Next, as shown in FIG. 1D, after the conductive film 24 is deposited over the entire surface, the exposed portion of the conductive film 24 on the second silicon oxide film 23 is removed. CMP is performed to form a wiring layer made of the conductive film 24.

According to the first embodiment, the second silicon oxide film 2 is formed on the surface of the wiring groove 22a in the porous film 22.
3 is deposited, the conductive material forming the conductive film 24 does not enter the pores of the porous film 22. Therefore, the deterioration of the insulating property of the porous film 22 can be prevented and the electromigration resistance of the wiring layer can be prevented. Deterioration can also be prevented.

(Second Embodiment) A semiconductor device and a method of manufacturing the same according to a second embodiment of the present invention will be described below. Since the second embodiment is characterized by the method of forming the porous film 22 in the first embodiment, only the method of forming the porous film 22 will be described below.

First, a silanol sol solution, which is a solution containing fine particles of a silanol condensate as shown in FIG. 2, is prepared,
The residual silanol groups (Si—OH) of the silanol condensate fine particles contained in the silanol sol solution are silylated with a silylating agent. FIG. 3 shows the silylation reaction, and FIG. 4 shows the silylated silanol condensate fine particles obtained by the silylation reaction. In FIG. 4, x is a silyl group. By replacing at least part of the OH groups constituting the silanol groups on the surface with silyl groups, silanol condensate fine particles (silylated silanol condensate fine particles) in which residual silanol is chemically modified with a silyl group can be obtained. FIG. 5A shows a state in which silanol condensate fine particles and a silyl group react with each other to form silylated silanol condensate fine particles.

As the silanol condensate fine particles, as shown in FIG. 2, those having a Si--H bond can be mentioned.

Triphenylsilanol is preferably used as the silylating agent. The reason is that the silylation reaction is easily promoted and thermal decomposition is easily caused in the heat treatment step described later.

The temperature of the silylation reaction is from room temperature to 5
A range of about 0 ° C is suitable.

The pore size of the porous membrane can be controlled to about 20 to 80 nm by adjusting the amount of the silylating agent added, and the pore size of the porous membrane increases as the amount of the silylating agent increases.

A reaction time of about 30 minutes is suitable for the silylation, but it is preferably changed depending on the kind of the silylating agent.

Since the step of obtaining the solution containing the silanol sol described above can be performed separately from the step of manufacturing the semiconductor device, it can be considered separately from the time required for the step of manufacturing the semiconductor device.

Next, as shown in FIG. 5B, a solution containing fine particles of silylated silanol condensate is spin-coated on a semiconductor substrate to form a coating film. The number of rotations in the spin coating can be set appropriately within a range where a good coating film can be formed, but 2000 to 4000 rpm is suitable.

Next, the coating film is subjected to a first heat treatment to thermally decompose the silyl group to perform desilylation treatment, as shown in FIG. 5 (c). In addition, in FIG. 5C, a circle indicates a silyl group which is thermally decomposed. This first
The heat treatment is preferably performed at a temperature of 100 ° C. to 200 ° C. for 1 minute to 5 minutes.

Next, a second heat treatment is performed on the desilylated coating film to dehydrate and condense residual silanol groups, thereby forming a porous film as shown in FIG. 5 (d). Form. The second heat treatment is 400 ° C to 4 ° C.
It is preferable that the temperature is 50 ° C. for 30 minutes to 1 hour.

In this way, the silylated layer formed on the surface of the silanol condensate fine particles ((SiO ₂ ) _n ) is thermally decomposed to form pores between the fine particles, so that FIG. A porous membrane as shown is formed.

As described above, according to the second embodiment,
In the step of forming the porous film, a long time heat treatment such as 9 hours to 24 hours is not necessary, and the heat treatment can be performed at a relatively low temperature.

(Examples) Examples for embodying the second embodiment will be described below.

A silanol sol solution obtained by adding 200 mg of triphenylsilanol as a silylating agent to 5 ml of a solution containing 10 wt% of silanol condensate fine particles in terms of SiO ₂ was stirred to conduct silanol condensation in the silanol sol solution. After the body particles were dissolved, they were left at room temperature for 17 hours. Next, the silanol sol solution was dropped onto a 6-inch silicon semiconductor substrate while passing through a 0.2 μm filter, and then the semiconductor substrate was placed at 4000 r.p.
A coating film was formed on the semiconductor substrate by holding for 20 seconds while rotating at m. in this case,
The reason for passing the silanol sol solution through the filter is
This is because impurities in the silanol sol solution are removed.
Then, it was confirmed by infrared spectrum (FTIR) that the silylation treatment was performed with triphenylsilanol.

Next, a coating film is formed by using a hot plate.
After performing the first heat treatment for 3 minutes at a temperature of 60 ° C.,
The second heat treatment was performed for 30 minutes at a temperature of 400 ° C. in a nitrogen atmosphere using an electric furnace.

When infrared spectrum measurement was performed after the first heat treatment, the absorption peak based on the triphenylsilanol group disappeared, and it was confirmed that pores were formed in the coating film by the first heat treatment. Was observed.

After the second heat treatment, the surface of the coating film was observed by SEM and it was confirmed that the coating film was made porous. Then, when the porous film was observed by a spectroscopic ellipso method, the film thickness was 357 nm and the refractive index was 1.25. Moreover, when the relative dielectric constant of the porous film was measured at 1 MHz by the CV method, the relative dielectric constant was 2.3.

As the silylating agent, instead of triphenylsilanol, trialkylalkoxysilane (alkyl group: methyl, ethyl, propyl, butyl; alkoxy group: ethoxy, methoxy), trialkylchlorosilane (alkyl group: methyl). , Ethyl, propyl, butyl), trialkylsilanol (alkyl group: methyl,
It is also possible to use ethyl, propyl, butyl), hexaphenyldisiloxane, alkoxytriphenylsilane, chlorotriphenylsilane, diphenyldialkoxysilane or diphenylsilanol.

(Third Embodiment) A semiconductor device and a method of manufacturing the same according to a third embodiment of the present invention will be described below. Since the third embodiment is also characterized by the method for forming the porous film 22 in the first embodiment, only the method for forming the porous film 22 will be described below.

First, a mixture of tetraethoxysilane and triethoxysilane is hydrolyzed to produce a silanol solution. FIG. 7 (a) shows a state in which tetraethoxysilane is hydrolyzed to produce a first reaction product (silanol), and FIG. 7 (b) is a state in which triethoxysilane is hydrolyzed to give a first reaction product (silanol). The state where the reaction product (silanol) of 2 is generated is shown. In this case, as shown in FIG. 7C, a dehydration condensation reaction between the first reaction product and the second reaction product also occurs. In this case, in addition to water added for hydrolysis, a mixed solution of ethanol or ethers may be added as a solvent. Further, a simple substance of triethoxysilane may be used instead of the mixture of tetraethoxysilane and triethoxysilane. When the above mixture is used, the mixing ratio is preferably 2: 1 to 1: 2 in terms of molar ratio.

Next, as shown in FIG. 7 (c), a dehydration condensation reaction between the first reaction product (silanol) and the second reaction product (silanol) occurs, and the silanol condensate fine particles are formed by aggregation. A silylating agent, such as triphenylsilanol, is added in the presence of acid or alkali as is being formed. By doing so, as shown in FIG. 8A, the first reaction product and triphenylsilanol react with each other to generate the third reaction product, and at the same time, as shown in FIG.
As shown in (b), the second reaction product reacts with triphenylsilanol to produce a fourth reaction product. Further, in the process in which the first reaction product and the second reaction product undergo a dehydration condensation reaction to form silanol condensate fine particles, the third reaction product and the fourth reaction product are silanol condensed. Since it is incorporated into the body fine particles, silanol condensate fine particles in which the third reaction product and the fourth reaction product are incorporated are formed.

Examples of the acid or alkali used in the silylation reaction step include protic acids such as acetic acid and amines.

The temperature of the silylation reaction is preferably in the range of room temperature to 50 ° C., and the time of the silylation reaction is preferably 5 hours to 20 hours. When the reaction temperature and the reaction time are set as described above, aggregation of the silanol by dehydration condensation reaction and silylation of the residual silanol group by the silylating agent proceed in parallel, so that the third reaction product and the fourth reaction product Silanol condensate fine particles in which the reaction product is incorporated are formed.

Next, a silanol sol solution containing fine particles of the silanol condensate in which the third reaction product and the fourth reaction product are incorporated is spin-coated on the semiconductor substrate to form a coating film. The number of rotations in spin coating can be appropriately set within a range where a good coating film can be formed.
000 to 4000 rpm is suitable.

Next, the coating film is subjected to a first heat treatment to thermally decompose the silyl groups in the silanol condensate fine particles to perform a desilylation treatment. The first heat treatment is preferably performed at a temperature of 100 ° C to 200 ° C for about 1 minute to 5 minutes.

Then, a second heat treatment is applied to the desilylated coating film to dehydrate and condense residual silanol groups to form a porous film. As the second heat treatment, a temperature of 400 ° C. to 450 ° C. for 30 minutes
About 1 hour is preferable.

In this way, as shown in FIG. 9, the silyl groups in the silanol condensate fine particles are thermally decomposed to form pores inside the fine particles, whereby a porous film is formed.

As described above, according to the third embodiment,
In the step of forming the porous film, a long time heat treatment such as 9 hours to 24 hours is not necessary, and the heat treatment can be performed at a relatively low temperature.

In the second embodiment, the porous film is formed by forming pores between the silanol condensate fine particles, whereas according to the third embodiment,
Since the porous film is formed by forming pores inside the silanol condensate fine particles, the size of the porous pores is smaller than that in the second embodiment.

(Examples) Examples for embodying the third embodiment will be described below.

First, after adding 500 mg of triethoxysilane to 5 ml of ethanol, 5 μl of acetic acid was added with vigorous stirring to obtain a first mixed solution, and then the first mixed solution was allowed to stand at room temperature for 1 hour. Next, 200 mg of triphenylsilanol as a silylating agent was added to the first mixed solution with stirring to obtain a second mixed solution, and then the second mixed solution was prepared.
The mixed solution of 1 was left at room temperature for 17 hours. Next, 2 ml of the second mixed solution was dropped onto the semiconductor substrate while passing through a 0.2 μm filter, and then the semiconductor substrate was placed at 4000 r.
A coating film was formed on the semiconductor substrate by rotating and holding at 20 pm for 20 seconds for spin coating.

Next, after a first heat treatment was performed for 3 minutes at a temperature of 160 ° C. using a hot plate, an electric furnace was used for 30 minutes at a temperature of 400 ° C. in a nitrogen atmosphere. Heat treatment was performed.

When infrared spectrum measurement was performed after the first heat treatment, the absorption peak based on the triphenylsilanol group disappeared, and it was confirmed that pores were formed in the coating film by the first heat treatment. Was observed.

After the second heat treatment, the surface of the coating film was observed by SEM to confirm that the coating film was porous. Then, when the porous film was observed by a spectroscopic ellipso method, the film thickness was 370 nm and the refractive index was 1.22. Moreover, when the relative dielectric constant of the porous film was measured at 1 MHz by the CV method, the relative dielectric constant was 2.1.

As the silylating agent, instead of triphenylsilanol, trialkylalkoxysilane (alkyl group: methyl, ethyl, propyl, butyl; alkoxy group: ethoxy, methoxy), trialkylchlorosilane (alkyl group: methyl). , Ethyl, propyl, butyl), trialkylsilanol (alkyl: methyl, ethyl, propyl, butyl), hexaphenyldisiloxane, alkoxytriphenylsilane, chlorotriphenylsilane, diphenyldialkoxysilane or diphenylsilanol can also be used. .

In this example, acetic acid was used as a catalyst for silanol dehydration condensation, but instead of this, other acids can be used as long as they are protic acids.

As the catalyst, an alkali such as amines may be used instead of the acid.

[0071]

According to the semiconductor device of the first aspect of the present invention, since the second silicon oxide film is interposed between the second wiring layer and the porous film, the second wiring layer is formed. Since the conductive material used does not enter the pores of the porous film, it is possible to prevent the deterioration of the insulation property of the interlayer insulating film made of the porous film and the deterioration of the electromigration resistance of the second wiring layer. This makes it possible to form a buried wiring in the interlayer insulating film made of a porous film.

According to the semiconductor device of the second aspect of the present invention, when the porous film is an organic SOG film, an insulating film having a low relative dielectric constant can be realized, and the porous film is an inorganic S film.
When the OG film is used, an insulating film having excellent heat resistance can be realized.

According to the semiconductor device manufacturing method of the third aspect of the present invention, the conductive film is deposited with the second silicon oxide film formed on the bottom and walls of the wiring groove formed in the porous film. Therefore, it is possible to prevent the conductive material forming the second wiring layer from entering the pores of the porous film, so that the insulation property of the interlayer insulating film made of the porous film is deteriorated and the electro-resistance of the second wiring layer is prevented. The semiconductor device according to the first aspect of the present invention, which can prevent the deterioration of migration, can be reliably manufactured.

According to the method of manufacturing a semiconductor device of the invention of claim 4, after the silyl group chemically modifying the silanol condensate fine particles is thermally decomposed to form pores between the silanol condensate fine particles, Since the residual silanol groups are dehydrated and condensed to condense the silanol condensate fine particles so as to surround the pores between the fine particles, the coating film on the semiconductor substrate is surely made porous. The interlayer insulating film that it has can be formed reliably.

According to the method for manufacturing a semiconductor device of the fifth aspect of the present invention, the residual silanol groups are dehydrated and condensed so as to surround the pores formed by the thermal decomposition of the silyl group, so that the silanol having the pores inside is formed. Since the condensate fine particles are formed, it is possible to reliably form the interlayer insulating film having the porous film made of an inorganic material.

According to the semiconductor device manufacturing method of the sixth aspect of the present invention, as in the fourth aspect of the invention, the silyl group chemically modifying the silanol condensate fine particles is thermally decomposed and the silanol condensate fine particles are separated from each other. After the pores are formed in, since the residual silanol groups are dehydrated and condensed to condense the silanol condensate fine particles so as to surround the pores between the fine particles, the coating film on the semiconductor substrate is surely made porous, An interlayer insulating film made of a porous film of an inorganic material can be reliably formed.

According to the method of manufacturing a semiconductor device of the invention of claim 7, as in the invention of claim 5, the residual silanol groups are dehydrated and condensed so as to surround the holes formed by thermal decomposition of the silyl groups. Since the silanol condensate fine particles having pores inside are formed, the interlayer insulating film made of a porous film of an inorganic material can be reliably formed.

[Brief description of drawings]

1A to 1D are cross-sectional views showing respective steps of a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing silanol condensate fine particles used in a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a silylation reaction in a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a state in which residual silanol groups of silanol condensate fine particles are silylated in the method for manufacturing a semiconductor device according to the second embodiment of the present invention.

5A to 5D are schematic views showing each manufacturing step of the method for manufacturing a semiconductor device according to the second embodiment of the present invention.

FIG. 6 is a schematic view showing a state in which a porous film is formed from silanol sol containing fine particles of silylated silanol condensate in the method for manufacturing a semiconductor device according to the second embodiment of the present invention.

7 (a) to 7 (c) show a chemical reaction in the method for manufacturing a semiconductor device according to the second embodiment of the present invention, and FIG. 7 (a) shows the first reaction due to hydrolysis of tetraethoxysilane.
Shows the state in which the reaction product is produced, (b) shows the state in which triethoxysilane is hydrolyzed to produce the second reaction product, and (c) shows the state in which the first reaction product and 2 shows a dehydration condensation reaction with the reaction product of 2.

8A and 8B show a chemical reaction in the method for manufacturing a semiconductor device according to the second embodiment of the present invention, and FIG. 8A shows a first reaction product and triphenylsilanol. Shows the state in which the third reaction product is produced by reacting with, and (b) shows the state in which the second reaction product and triphenylsilanol react with each other to produce the fourth reaction product. ing.

FIG. 9 is a view showing a method of manufacturing a semiconductor device according to a third embodiment of the present invention, in which the silyl group is thermally decomposed from the silanol condensate fine particles into which the third and fourth reaction products are incorporated, and the residual silanol group is removed. FIG. 3 is a schematic diagram showing a state in which pores are formed in fine particles by dehydration condensation.

FIG. 10 is a sectional view of a semiconductor device according to a first conventional example.

FIG. 11 is a cross-sectional view of a semiconductor device according to a second conventional example.

[Explanation of symbols]

 20 Semiconductor Substrate 21 First Silicon Oxide Film 21a Through Hole 22 Porous Film 22a Wiring Groove 23 Second Silicon Oxide Film 24 Conductive Film

Claims (7)

[Claims] 1. A semiconductor substrate on which a first wiring layer is formed, a first silicon oxide film formed on the semiconductor substrate, and a porous film formed on the first silicon oxide film. A film, a through hole formed in the first silicon oxide film, a wiring groove formed in the porous film and communicating with the through hole, and a bottom portion and a wall portion of the wiring groove. A second silicon oxide film, a contact made of a conductive film buried in the through hole, and a second wiring layer made of a conductive film buried inside the second silicon oxide film in the wiring trench. A semiconductor device comprising: 2. The semiconductor device according to claim 1, wherein the porous film is made of an organic SOG film or an inorganic SOG film. 3. A first step of depositing a first silicon oxide film on a semiconductor substrate on which a first wiring layer is formed, and a porous film is deposited on the first silicon oxide film. A second step; a third step of forming a wiring groove in the porous film; and a second silicon oxide film which does not fill the wiring groove on the porous film including the wiring groove. Fourth to be deposited
And a fifth step of forming a through hole in the second silicon oxide film and the first silicon oxide film, and on the second silicon oxide film including the through hole and the wiring trench. Sixth, the conductive film is deposited over the entire surface
And a seventh step of removing a portion of the conductive film exposed on the second silicon oxide film to form a second wiring layer made of the conductive film. A method of manufacturing a semiconductor device, comprising: 4. The second step is a step of chemically modifying residual silanol groups of the silanol condensate fine particles with a silyl group by adding a silylating agent to a silanol sol solution containing the silanol condensate fine particles. Applying a silanol sol solution containing the silanol condensate fine particles chemically modified with the silyl group to a semiconductor substrate to form a coating film; and subjecting the coating film to heat treatment to thermally decompose the silyl group. The method of manufacturing a semiconductor device according to claim 3, further comprising: dehydrating and condensing the residual silanol groups to make the coating film porous. 5. The second step is a step of chemically modifying a residual silanol group of silanol contained in the silanol solution with a silyl group by adding a silylating agent to the silanol solution in the presence of an acid or an alkali. And a step of applying a silanol solution containing silanol chemically modified by the silyl group to form a coating film on a semiconductor substrate, and heat-treating the coating film to thermally decompose the silyl group and 4. The method for manufacturing a semiconductor device according to claim 3, further comprising the step of making the coating film porous by dehydrating and condensing residual silanol groups. 6. An interlayer insulating film forming step of forming an interlayer insulating film made of a porous film on a semiconductor substrate having a first wiring layer formed thereon, and a second wiring layer being formed on the interlayer insulating film. A method of manufacturing a semiconductor device comprising a wiring layer forming step to be formed, wherein the interlayer insulating film forming step comprises adding a silylating agent to a silanol sol solution containing fine particles of a silanol condensate to obtain the silanol condensate. A step of chemically modifying the residual silanol groups of the fine particles with a silyl group; a step of applying a silanol sol solution containing the silanol condensate fine particles chemically modified by the silyl group onto a semiconductor substrate to form a coating film; Heat-treating the coating film to thermally decompose the silyl groups and dehydrate and condense the residual silanol groups to make the coating film porous. The method of manufacturing a semiconductor device according to claim and. 7. An interlayer insulating film forming step of forming an interlayer insulating film made of a porous film on a semiconductor substrate having a first wiring layer formed thereon, and a second wiring layer being formed on the interlayer insulating film. A method for manufacturing a semiconductor device comprising a wiring layer forming step to be formed, wherein the interlayer insulating film forming step comprises adding a silylating agent to a silanol solution in the presence of an acid or an alkali to form a silanol solution. A step of chemically modifying a residual silanol group of silanol contained with a silyl group, a step of applying a silanol solution containing silanol chemically modified by the silyl group on a semiconductor substrate to form a coating film, and the coating film. And a thermal treatment to thermally decompose the silyl group and dehydrate and condense the residual silanol groups to make the coating film porous. The method of manufacturing a semiconductor device to be.