JP3877472B2 - Method for forming interlayer insulating film - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming an interlayer insulating film having a multilayer wiring structure in a semiconductor integrated circuit device, and in particular, an interlayer insulating film having a low dielectric constant by plasma polymerization of an organic-inorganic hybrid material (a siloxane material having an organic silicon bond). Relates to a method of forming
[0002]
[Prior art]
As an interlayer insulating film made of a siloxane material having an organic silicon bond, an organic SOG film formed by a coating method and a siloxane film formed by plasma polymerization are known.
[0003]
As a method for forming an organic SOG film, a solution of a siloxane polymer having an organic silicon bond is applied on a substrate at room temperature to obtain a coating film, and then the coating film is subjected to a heat treatment using a hot plate to obtain a solvent. Is generally performed, followed by baking at a high temperature of 400 ° C. in an inert gas atmosphere. In this baking step, since the silanol (Si—OH) bond constituting the siloxane polymer undergoes a dehydration condensation reaction to form a siloxane polymer, the organic SOG is densified.
[0004]
Moreover, the method of forming a siloxane film by plasma polymerization is a method in which an organic silane and an oxidizing agent such as nitric oxide are polymerized by a plasma CVD method to generate an organic silanol, and then the organic silanol is polymerized to each other. This is a method of forming a siloxane film having an organic silicon bond.
[0005]
[Problems to be solved by the invention]
However, according to the conventional method for forming an organic SOG film, since the solvent is evaporated by performing a heat treatment on the coating film, the solvent in the organic SOG film is not completely removed. In the heat treatment step performed after the film formation, a degassing phenomenon that gradually evaporates occurs. For this reason, when a metal film is embedded in the contact hole, a defect in the embedding occurs due to a degassing phenomenon, which causes an abnormality of an increase in contact resistance.
[0006]
In addition, according to the conventional method of forming a siloxane film by plasma polymerization, when a silanol polymer is formed by dehydration condensation reaction of silanol bonds, unreacted silanol remains in the organic SOG film. The dehydration condensation reaction of the residual silanol gradually proceeds due to the thermal history in the integration process performed on. For this reason, a degassing phenomenon in which water generated by a dehydration condensation reaction of residual silanol evaporates occurs, thereby causing an abnormality of an increase in contact resistance.
[0007]
The degassing phenomenon described above also occurs in a siloxane film formed by plasma polymerization. That is, silanol remains in the siloxane film when the organic silane is polymerized with the oxidizing agent in the plasma, so that a degassing phenomenon occurs due to the residual silanol.
[0008]
In view of the above, an object of the present invention is to provide a method of forming an interlayer insulating film that is less susceptible to degassing and has excellent heat resistance.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a first method for forming an interlayer insulating film according to the present invention is a method of plasma-polymerizing an organic alkoxysilane having an alkoxyl group and an organic group bonded to silicon to form an interlayer composed of an organic-inorganic hybrid film. An insulating film is formed.
[0010]
According to the method for forming the first interlayer insulating film, since the organic alkoxysilane is plasma-polymerized, the organic component of the organic alkoxysilane is effectively taken into the organic-inorganic hybrid film, so that the generation of silanol groups is suppressed.
[0011]
In the second method for forming an interlayer insulating film according to the present invention, an interlayer insulating film made of an organic-inorganic hybrid film is formed by plasma polymerization of an organic silicon compound having a Si—O—Si bond or a Si—N—Si bond. .
[0012]
According to the second interlayer insulating film formation method, an organic-inorganic hybrid film is formed by plasma polymerizing an organic silicon compound having a Si—O—Si bond or a Si—N—Si bond. Effective incorporation into the film and the generation of silanol groups are suppressed.
[0013]
A third interlayer insulating film forming method according to the present invention includes an organic silicon compound having a Si—O—Si bond or a Si—N—Si bond, an alkoxyl group, and an organic alkoxysilane having an organic group bonded to silicon. This mixture is plasma-polymerized to form an interlayer insulating film made of an organic / inorganic hybrid film.
[0014]
According to the third method for forming an interlayer insulating film, when an organic silicon compound having a Si—O—Si bond or a Si—N—Si bond is subjected to plasma polymerization, the resulting organic-inorganic hybrid film has relatively many organic groups. Thus, when the organic alkoxysilane is plasma polymerized, Si—O bonds are relatively increased in the obtained organic-inorganic hybrid film.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, although the formation method of the interlayer insulation film concerning each embodiment of the present invention is explained, the main material used for each embodiment is explained as the premise.
[0016]
The first main raw material is an organic alkoxysilane having an alkoxyl group and an organic group bonded to silicon, and an organic alkoxysilane represented by the following general formula (1), (2) or (3) is used alone. Or it can be mixed and used.
[0017]
General formula (1): R¹Si (OR²)_Three(However, R¹Is an alkyl group, an allyl group or an aryl group, and R²Are the same or different and are an alkyl group, an allyl group or an aryl group. )
General formula (2): R¹ ₂Si (OR²)₂(However, R¹Are the same or different and are an alkyl group, an allyl group or an aryl group, and R²Are the same or different and are an alkyl group, an allyl group or an aryl group. )
General formula (3): R¹ _ThreeSi (OR²) (However, R¹Are the same or different and are an alkyl group, an allyl group or an aryl group, and R²Is an alkyl group, an allyl group or an aryl group. )
The second main raw material is an organosilicon compound having a Si—O—Si bond or a Si—N—Si bond, and specifically, hexamethyldisiloxane, hexaphenyldisiloxane, hexamethyldisilazane, or hexa Examples thereof include phenyl disilazane, but are not limited thereto.
[0018]
(First embodiment)
The first embodiment is a method for plasma-polymerizing a first main raw material to form an interlayer insulating film made of an organic-inorganic hybrid film. As the first main raw material, methyltriethoxysilane (CH_ThreeSi (OC₂H_Five)_Three: In general formula (1), R¹Is CH_ThreeAnd R²Is C₂H_FiveIt is. ) Is used.
[0019]
3.0 ml / min of methyltriethoxysilane is introduced into the processing chamber by liquid mass flow, and argon gas as a dilution gas is introduced into the processing chamber at a flow rate of 1000 sccm. With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage (lower electrode) holding the substrate in the processing chamber.
[0020]
When the substrate temperature (film deposition temperature) was set to 400 ° C. and a film was formed at a deposition rate of 300 nm / min, an organic-inorganic hybrid film having a relative dielectric constant of 3.1 was obtained.
[0021]
When the thermal stability of the organic / inorganic hybrid film was evaluated from the decrease in film thickness associated with the heat treatment, the shrinkage ratio was 1.0% or less in the heat treatment at 450 ° C. or higher, and it was very stable against the heat treatment. Was confirmed.
[0022]
According to the first embodiment, since organic alkoxysilane such as methyltriethoxysilane is plasma-polymerized, the organic component of the organic alkoxysilane is effectively incorporated into the organic-inorganic hybrid film. For this reason, since the generation of silanol groups is suppressed, the degassing phenomenon caused by the residual silanol hardly occurs, and an interlayer insulating film having high heat resistance and low hygroscopicity can be formed.
[0023]
In addition, since the plasma polymerization is performed in a non-oxidizing atmosphere substantially free of an oxidizing agent, generation of silanol groups is further suppressed, so that an interlayer insulating film having higher heat resistance and lower hygroscopicity is formed. be able to.
[0024]
(Second Embodiment)
The second embodiment is a method for forming an interlayer insulating film by plasma-polymerizing the first main raw material to obtain an organic-inorganic hybrid film, and then subjecting the organic-inorganic hybrid film to a heat treatment. 1 as a main raw material, methyltriethoxysilane (CH_ThreeSi (OC₂H_Five)_Three: In general formula (1), R¹Is CH_ThreeAnd R²Is C₂H_FiveIt is. ) Is used.
[0025]
2.0 ml / min of methyltriethoxysilane is introduced into the processing chamber by liquid mass flow, and argon gas as a dilution gas is introduced into the processing chamber at a flow rate of 1000 sccm. With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage holding the substrate in the processing chamber.
[0026]
The organic / inorganic hybrid film obtained by forming the substrate at a temperature of 60 ° C., for example, is subjected to a heat treatment by holding it at 400 ° C. in an inert gas atmosphere for 30 minutes. Form.
[0027]
The substrate temperature may not be 60 ° C., but is preferably 300 ° C. or less.
[0028]
The heat treatment performed on the organic-inorganic hybrid film may not be 400 ° C., but is preferably performed at a temperature higher by 100 ° C. than the temperature of plasma polymerization.
[0029]
According to the second embodiment, since the film is formed at a low temperature of 300 ° C. or lower, a volatile organic component generated by plasma decomposition of the organic alkoxysilane remains in the organic-inorganic hybrid film. In addition, since the organic-inorganic hybrid film is subjected to heat treatment at a temperature 100 ° C. higher than the temperature of plasma polymerization, the volatile organic components remaining in the organic-inorganic hybrid film are volatilized. For this reason, since the porous and low-density organic-inorganic hybrid film progresses, the relative dielectric constant of the interlayer insulating film is further reduced.
[0030]
In addition, since the siloxane skeleton is formed in the heat treatment step after the film formation, the relative dielectric constant of the interlayer insulating film is further reduced.
[0031]
Therefore, according to the second embodiment, an interlayer insulating film having a relative dielectric constant as low as about 2.2 is obtained.
[0032]
Note that when an oxidizing agent such as oxygen is mixed in the inert gas in the heat treatment step after the film formation, the organic component is decomposed during the heat treatment, so that the porous formation can be promoted.
[0033]
In addition, if the heat treatment after film formation is performed in a reducing atmosphere, volatilization of the organic components remaining in the organic-inorganic hybrid film can be promoted, so that the organic-inorganic hybrid film can be further made porous. The relative dielectric constant of the interlayer insulating film can be further reduced.
[0034]
(Third embodiment)
The third embodiment is a method of forming an interlayer insulating film by performing plasma treatment on the organic-inorganic hybrid film after plasma-polymerizing the first main raw material to obtain an organic-inorganic hybrid film, As the first main raw material, methyltriethoxysilane (CH_ThreeSi (OC₂H_Five)_Three: In general formula (1), R¹Is CH_ThreeAnd R²Is C₂H_FiveIt is. ) Is used.
[0035]
2.0 ml / min of methyltriethoxysilane is introduced into the processing chamber by liquid mass flow, and argon gas as a dilution gas is introduced into the processing chamber at a flow rate of 1000 sccm. With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage holding the substrate in the processing chamber.
[0036]
Plasma treatment is performed on the organic-inorganic hybrid film formed by plasma polymerization with the substrate temperature set to 400 ° C. That is, hydrogen gas is introduced into the processing chamber maintained at a pressure of 2.0 Torr at a flow rate of 5000 sccm, and high frequency power of 13.56 MHz is applied to the upper electrode in the processing chamber at a power of 500 W for 5 minutes of plasma. Perform processing.
[0037]
According to the third embodiment, as in the second embodiment, since the film is made more porous and lower in density, a film having a lower relative dielectric constant than that in the first embodiment can be obtained. .
[0038]
When the substrate temperature is set to 350 ° C. or lower, for example, 300 ° C., and the film is formed by plasma polymerization, plasma treatment is performed at a temperature 50 ° C. higher than the temperature of plasma polymerization, for example, 400 ° C. However, the relative dielectric constant can be further reduced.
[0039]
In the third embodiment, the plasma treatment is performed in a reducing gas atmosphere. However, the reducing gas atmosphere may not be used.
[0040]
In addition, if the plasma treatment after the film formation is performed in a reducing atmosphere, volatilization of the organic components remaining in the organic-inorganic hybrid film can be promoted, so that the organic-inorganic hybrid film can be made more porous. Thus, the dielectric constant of the interlayer insulating film can be further reduced.
[0041]
(Fourth embodiment)
The fourth embodiment is a method of plasma-polymerizing the second main material to form an interlayer insulating film made of an organic-inorganic hybrid film, and the second main material has a Si—O—Si bond. Hexamethyldisiloxane ((CH_Three)_ThreeSiOSi (CH_Three)_Three) Is used.
[0042]
1.0 ml / min of hexamethyldisiloxane is introduced into the processing chamber by liquid mass flow, and argon gas as a dilution gas is introduced into the processing chamber at a flow rate of 1000 sccm. With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage holding the substrate in the processing chamber.
[0043]
When the substrate temperature was set to 400 ° C. and a film was formed at a deposition rate of 300 nm / min, an organic-inorganic hybrid film having a relative dielectric constant of 2.5 was obtained.
[0044]
When the thermal stability of the organic / inorganic hybrid film was evaluated from the decrease in film thickness associated with the heat treatment, it was confirmed that the heat shrinkage at 450 ° C or higher was 0.5% or less and was very stable. It was.
[0045]
According to the fourth embodiment, since the plasma polymerization is performed in a non-oxidizing atmosphere substantially free of an oxidant, the organic component is effectively taken into the film and the generation of silanol groups is further suppressed. As a result, an outgassing phenomenon caused by residual silanol hardly occurs, and an interlayer insulating film having higher heat resistance and lower hygroscopicity can be formed.
[0046]
(Fifth embodiment)
The fifth embodiment is a method of forming an interlayer insulating film by plasma-treating the second main raw material to obtain an organic-inorganic hybrid film and then subjecting the organic-inorganic hybrid film to a heat treatment. As the main raw material of 2, hexamethyldisiloxane having Si—O—Si bond ((CH_Three)_ThreeSiOSi (CH_Three)_Three) Is used.
[0047]
1.0 ml / min of hexamethyldisiloxane is introduced into the processing chamber by liquid mass flow, and argon gas as a dilution gas is introduced into the processing chamber at a flow rate of 1000 sccm. With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage holding the substrate in the processing chamber.
[0048]
An organic / inorganic hybrid film obtained by forming a film at a substrate temperature of 60 ° C., for example, is subjected to a heat treatment at 400 ° C. for 30 minutes in an inert gas atmosphere to perform an organic / inorganic hybrid film. Get a membrane.
[0049]
The substrate temperature may not be 60 ° C., but is preferably 300 ° C. or less, and more preferably 200 ° C. or less. When the film is formed at such a low temperature, the density of the film is lowered as compared with the case where the film is formed at a high temperature, so that the relative dielectric constant of the obtained film is further reduced.
[0050]
According to the fifth embodiment, since the film is formed at a low temperature of 300 ° C. or lower, a volatile organic component generated by plasma decomposition of the organic silicon compound remains in the organic-inorganic hybrid film. In addition, since the organic-inorganic hybrid film is subjected to heat treatment at a temperature 100 ° C. higher than the temperature of plasma polymerization, the volatile organic components remaining in the organic-inorganic hybrid film are volatilized. For this reason, since the porous and low-density organic-inorganic hybrid film progresses, the relative dielectric constant of the interlayer insulating film is further reduced.
[0051]
In addition, since the siloxane skeleton is formed in the heat treatment step after the film formation, the relative dielectric constant of the interlayer insulating film is further reduced.
[0052]
For this reason, according to the fifth embodiment, an interlayer insulating film having a relative dielectric constant as low as about 2.2 was obtained.
[0053]
Note that when an oxidizing agent such as oxygen is mixed in the inert gas in the heat treatment step after the film formation, the organic component is decomposed during the heat treatment, so that the porous formation can be promoted.
[0054]
In addition, if the heat treatment after film formation is performed in a reducing atmosphere, volatilization of the organic components remaining in the organic-inorganic hybrid film can be promoted, so that the organic-inorganic hybrid film can be further made porous. The relative dielectric constant of the interlayer insulating film can be further reduced.
[0055]
(Sixth embodiment)
The sixth embodiment is a method of forming an interlayer insulating film by performing plasma treatment on the organic-inorganic hybrid film after plasma-polymerizing the second main raw material to obtain an organic-inorganic hybrid film, As the second main raw material, hexamethyldisiloxane having Si—O—Si bond ((CH_Three)_ThreeSiOSi (CH_Three)_Three) Is used.
[0056]
1.0 ml / min of hexamethyldisiloxane is introduced into the processing chamber by liquid mass flow, and argon gas as a dilution gas is introduced into the processing chamber at a flow rate of 1000 sccm. With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage holding the substrate in the processing chamber.
[0057]
Plasma treatment is performed on the organic-inorganic hybrid film obtained by forming the film at a substrate temperature of 400 ° C. That is, hydrogen gas is introduced into the processing chamber maintained at a pressure of 2.0 Torr at a flow rate of 5000 sccm, and high frequency power of 13.56 MHz is applied to the upper electrode in the processing chamber at a power of 500 W for 5 minutes of plasma. Perform processing.
[0058]
According to the sixth embodiment, as in the fifth embodiment, since the film is made more porous and lower in density, a film having a lower relative dielectric constant can be obtained.
[0059]
When the substrate temperature is set to 350 ° C. or lower, for example, 300 ° C., and the film is formed by plasma polymerization, plasma treatment is performed at a temperature 50 ° C. higher than the temperature of plasma polymerization, for example, 400 ° C. However, the relative dielectric constant can be further reduced.
[0060]
In the sixth embodiment, the plasma treatment is performed in a reducing gas atmosphere. However, the reducing gas atmosphere may not be used.
[0061]
In addition, if the plasma treatment after the film formation is performed in a reducing atmosphere, volatilization of the organic components remaining in the organic-inorganic hybrid film can be promoted, so that the organic-inorganic hybrid film can be made more porous. Thus, the dielectric constant of the interlayer insulating film can be further reduced.
[0062]
(Seventh embodiment)
The seventh embodiment is a method of forming an interlayer insulating film made of an organic-inorganic hybrid film by plasma polymerization of a mixture of a first main raw material and a second main raw material, and the first main raw material is , Methyltriethoxysilane (CH_ThreeSi (OC₂H_Five)_Three: In general formula (1), R¹Is CH_ThreeAnd R²Is C₂H_FiveIt is. ) And hexamethyldisiloxane having Si—O—Si bond ((CH_Three)_ThreeSiOSi (CH_Three)_Three) Is used.
[0063]
A mixture of methyltriethoxysilane and hexamethyldisiloxane is introduced into the processing chamber at a flow rate of 1.0 ml / min by liquid mass flow, and argon gas as a dilution gas is introduced into the processing chamber at a flow rate of 1000 sccm. With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage holding the substrate in the processing chamber.
[0064]
When the substrate temperature was set to 400 ° C. and a film was formed at a deposition rate of 300 nm / min, an organic-inorganic hybrid film having a relative dielectric constant of 2.5 was obtained.
[0065]
When the thermal stability of the organic / inorganic hybrid film was evaluated from the decrease in film thickness associated with the heat treatment, it was confirmed that the heat shrinkage at 450 ° C or higher was 0.5% or less and was very stable. It was.
[0066]
By the way, as in the first embodiment, the organic-inorganic hybrid film obtained by plasma polymerization of the organic alkoxysilane has a relatively large number of Si—O bonds and a relatively small number of organic groups. It has the advantage of high mechanical strength as well as high strength, but has a weak point that the relative dielectric constant is relatively high. As in the fourth embodiment, Si—O—Si bond or Si—N—Si bond The organic-inorganic hybrid film obtained by plasma polymerization of an organic silicon compound having an organic compound has an advantage that the relative dielectric constant is low because of relatively large number of organic groups and relatively few Si-O bonds. However, there is a weak point that adhesion and mechanical strength are low.
[0067]
However, according to the seventh embodiment, each of the organic-inorganic hybrid films obtained by plasma polymerization of a mixture of an organoalkoxysilane and an organic silicon compound having a Si—O—Si bond or Si—N—Si bond, When used alone, the weak point is compensated, and the adhesiveness and mechanical strength are increased and the relative dielectric constant is decreased.
[0068]
In particular, in the seventh embodiment, since a mixture of methyltriethoxysilane and hexamethyldisiloxane is plasma-polymerized, the content of ethoxy groups remaining in the film is determined when organic alkoxysilane is used alone. Since the number is smaller than that, deterioration of film quality due to moisture absorption can be further suppressed.
[0069]
When methyltriethoxysilane is plasma-polymerized alone, the deposition rate is about 100 nm / min and slow, but the deposition rate is 300 nm because methyltriethoxysilane and hexamethyldisiloxane are copolymerized. / Min. This is considered to be because hexamethyldisiloxane is easily dissociated radically, and the dissociated hexamethyldisiloxane reacts with methyltriethoxysilane, which accelerates the polymerization reaction.
[0070]
(Eighth embodiment)
The eighth embodiment is a method for plasma-polymerizing a mixture of a first main raw material and a second main raw material to form an interlayer insulating film made of an organic-inorganic hybrid film, and the first main raw material is , Methyltriethoxysilane (CH_ThreeSi (OC₂H_Five)_Three: In general formula (1), R¹Is CH_ThreeAnd R²Is C₂H_FiveIt is. ) And hexamethyldisiloxane having Si—O—Si bond ((CH_Three)_ThreeSiOSi (CH_Three)_Three) Is used.
[0071]
A mixture of methyltriethoxysilane and hexamethyldisiloxane is introduced into the processing chamber at a flow rate of 1.0 ml / min by liquid mass flow, and argon gas as a dilution gas is introduced into the processing chamber at a flow rate of 1000 sccm. With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage holding the substrate in the processing chamber.
[0072]
An organic / inorganic hybrid film obtained by forming a film at a substrate temperature of 60 ° C., for example, is subjected to a heat treatment at 400 ° C. for 30 minutes in an inert gas atmosphere to perform an organic / inorganic hybrid film. Get a membrane.
[0073]
The substrate temperature may not be 60 ° C., but is preferably 300 ° C. or less. When the film is formed at such a low temperature, the density of the film is lowered as compared with the case where the film is formed at a high temperature, so that the relative dielectric constant of the obtained film is further reduced.
[0074]
According to the eighth embodiment, in order to form a film at a low temperature of 300 ° C. or lower, the volatile organic component generated by plasma decomposition of the organic silicon compound remains in the film, and the volatile organic component Volatilizes by heat treatment after film formation. In this heat treatment step, a siloxane skeleton is formed and the film is made more porous and lower in density, so that a film having a lower relative dielectric constant can be obtained. For this reason, according to the eighth embodiment, an interlayer insulating film having a relative dielectric constant as low as about 2.2 was obtained.
[0075]
In the heat treatment step, when an oxidant such as oxygen is mixed in the inert gas, the organic component is decomposed during the heat treatment, so that it is possible to further increase the porosity and further decrease the relative dielectric constant.
[0076]
In addition, if the heat treatment after film formation is performed in a reducing atmosphere, volatilization of the organic components remaining in the organic-inorganic hybrid film can be promoted, so that the organic-inorganic hybrid film can be further made porous. The relative dielectric constant of the interlayer insulating film can be further reduced.
[0077]
(Ninth embodiment)
In the ninth embodiment, an organic / inorganic hybrid film is obtained by plasma polymerization of a mixture of a first main material and a second main material, and then plasma treatment is performed on the organic / inorganic hybrid film to perform interlayer insulation. In the method for forming a film, the first main raw material is methyltriethoxysilane (CH_ThreeSi (OC₂H_Five)_Three: In general formula (1), R¹Is CH_ThreeAnd R²Is C₂H_FiveAnd the second main raw material is hexamethyldisiloxane having (Si—O—Si bond) ((CH_Three)_ThreeSiOSi (CH_Three)_Three) Is used.
[0078]
A mixture of methyltriethoxysilane and hexamethyldisiloxane is introduced into the processing chamber at a flow rate of 1.0 ml / min by liquid mass flow, and argon gas as a dilution gas is introduced into the processing chamber at a flow rate of 1000 sccm. With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage holding the substrate in the processing chamber.
[0079]
Plasma treatment is performed on the organic-inorganic hybrid film obtained by forming the film at a substrate temperature of 400 ° C. That is, hydrogen gas is introduced into the processing chamber maintained at a pressure of 2.0 Torr at a flow rate of 5000 sccm, and high frequency power of 13.56 MHz is applied to the upper electrode in the processing chamber at a power of 500 W for 5 minutes of plasma. Perform processing.
[0080]
According to the ninth embodiment, as in the eighth embodiment, since the film is made more porous and lower in density, a film having a lower relative dielectric constant can be obtained.
[0081]
When the substrate temperature is set to 350 ° C. or lower, for example, 300 ° C., and the film is formed by plasma polymerization, plasma treatment is performed at a temperature 50 ° C. higher than the temperature of plasma polymerization, for example, 400 ° C. However, the relative dielectric constant can be further reduced.
[0082]
In the ninth embodiment, the plasma treatment is performed in a reducing gas atmosphere. However, the reducing gas atmosphere may not be used.
[0083]
In addition, if the plasma treatment after the film formation is performed in a reducing atmosphere, volatilization of the organic components remaining in the organic-inorganic hybrid film can be promoted, so that the organic-inorganic hybrid film can be made more porous. Thus, the dielectric constant of the interlayer insulating film can be further reduced.
[0084]
(Tenth embodiment)
The tenth embodiment is a method of plasma-polymerizing a mixture of two kinds of first main raw materials to form an interlayer insulating film made of an organic-inorganic hybrid film, and specifically, methyltriethoxysilane (CH_ThreeSi (OC₂H_Five)_Three: In general formula (1), R¹Is CH_ThreeAnd R²Is C₂H_FiveIt is. ) And dimethyldiethoxysilane ((CH_Three)₂Si (OC₂H_Five)₂: In general formula (2), R¹Is CH_ThreeAnd R²Is C₂H_FiveIt is. ).
[0085]
2.0 ml / min of methyltriethoxysilane and 1.0 ml / min of dimethyldiethoxysilane are introduced into the processing chamber by liquid mass flow, and argon gas as a dilution gas is introduced into the processing chamber at a flow rate of 1000 sccm. . With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage (lower electrode) holding the substrate in the processing chamber.
[0086]
When the substrate temperature was set to 400 ° C. and a film was formed at a deposition rate of 300 nm / min, an organic-inorganic hybrid film having a relative dielectric constant of 2.6 was obtained.
[0087]
When the thermal stability of the organic / inorganic hybrid film was evaluated from the decrease in film thickness associated with the heat treatment, it was confirmed that the shrinkage was 1.0% or less in the heat treatment at 450 ° C. or higher and it was very stable. It was.
[0088]
According to the tenth embodiment, the first organic alkoxysilane (methyltriethoxysilane) having a high alkoxyl group content and the second organic alkoxysilane (dimethyldiethoxysilane) having a relatively high organic group content. Therefore, the first organic alkoxysilane contributes to the formation of the siloxane skeleton, improves the thermal stability and mechanical strength of the resulting film, and the second organic alkoxysilane is used in the film. The relative dielectric constant of the resulting film is decreased by increasing the content of the organic component.
[0089]
For this reason, in the obtained interlayer insulating film, thermal stability and mechanical strength are improved, and the relative dielectric constant is lowered.
[0090]
(Eleventh embodiment)
The eleventh embodiment is a method of plasma-polymerizing a mixture of three kinds of first main raw materials to form an interlayer insulating film made of an organic-inorganic hybrid film. Specifically, methyltriethoxysilane (CH_ThreeSi (OC₂H_Five)_Three: In general formula (1), R¹Is CH_ThreeAnd R²Is C₂H_FiveIt is. ) And dimethyldiethoxysilane ((CH_Three)₂Si (OC₂H_Five)₂: In general formula (2), R¹Is CH_ThreeAnd R²Is C₂H_FiveIt is. ) And trimethylethoxysilane ((CH_Three)_ThreeSi (OC₂H_Five): In general formula (3), R¹Is CH_ThreeAnd R²Is C₂H_FiveIt is. ).
[0091]
2.0 ml / min of methyltriethoxysilane, 1.0 ml / min of dimethyldiethoxysilane, and 0.5 ml / min of trimethylethoxysilane are introduced into the treatment chamber by liquid mass flow, and argon as a diluent gas is introduced. Gas is introduced into the processing chamber at a flow rate of 1000 sccm. With the pressure in the processing chamber maintained at 1.5 Torr, high frequency power of 13.56 MHz is applied at a power of 600 W to the upper electrode facing the sample stage (lower electrode) holding the substrate in the processing chamber.
[0092]
When the substrate temperature was set to 400 ° C. and a film was formed at a deposition rate of 300 nm / min, an organic-inorganic hybrid film having a relative dielectric constant of 2.6 was obtained.
[0093]
When the thermal stability of the organic / inorganic hybrid film was evaluated from the decrease in film thickness associated with the heat treatment, it was confirmed that the shrinkage was 1.0% or less in the heat treatment at 450 ° C. or higher and it was very stable. It was.
[0094]
According to the eleventh embodiment, the first organic alkoxysilane having a high alkoxyl group content, the second organic alkoxysilane having a relatively high organic group content, and the organic group having a very high application rate. The first organic alkoxysilane contributes to the formation of the siloxane skeleton and improves the thermal stability and mechanical strength of the resulting film, and the second and third organic alkoxysilanes. The organic alkoxysilane increases the content of the organic component in the film and lowers the relative dielectric constant of the obtained film.
[0095]
Hereinafter, a specific example of a multilayer wiring structure in which an interlayer insulating film (hereinafter referred to as an interlayer insulating film of the present invention) obtained by the methods according to the first to eleventh embodiments is used will be described with reference to FIG. 2 (a) and 2 (b), FIGS. 3 (a) to 3 (b) and FIGS. 4 (a) and 4 (b).
[0096]
FIG. 1 (a) shows a multilayer wiring structure having metal wiring patterned by etching, and a first-layer metal wiring 2 and a second-layer metal wiring 3 formed on the substrate 1 are first layers. The second-layer metal wiring 3 and the third-layer metal wiring (not shown) are connected by the second contact 5.
[0097]
A first insulating film 11 made of the interlayer insulating film of the present invention is formed between the metal wirings 2 of the first layer. A second insulating film 12 made of a silicon oxide film is formed between the first-layer metal wiring 2 and the second-layer metal wiring 3, and the first contact 4 is formed on the second insulating film 12. ing. A third insulating film 13 made of the interlayer insulating film of the present invention is formed between the metal wirings 3 of the second layer. A fourth insulating film 14 made of a silicon oxide film is formed between the second layer metal wiring 3 and the third layer metal wiring, and the second contact 5 is formed on the fourth insulating film 14. Yes.
[0098]
FIG. 1B shows a multilayer wiring structure having metal wiring patterned by etching. The first-layer metal wiring 2 and the second-layer metal wiring 3 formed on the substrate 1 are the first layer. The second-layer metal wiring 3 and the third-layer metal wiring (not shown) are connected by the second contact 5.
[0099]
A first insulating film 21 made of an interlayer insulating film of the present invention is formed between the metal wirings 2 of the first layer and on the metal wiring 2 of the first layer, and the first insulating film 21 and the second layer are formed. A second insulating film 22 made of a silicon oxide film is formed between the metal wiring 3. A third insulating film 23 made of an interlayer insulating film of the present invention is formed between the second layer metal wirings 3 and on the second layer metal wirings 3, and the third insulating film 23 and the third layer are formed. A fourth insulating film 24 made of a silicon oxide film is formed between the metal wirings.
[0100]
FIG. 2A shows a multilayer wiring structure having metal wiring patterned by etching. The first-layer metal wiring 2 and the second-layer metal wiring 3 formed on the substrate 1 are the first layer. The second-layer metal wiring 3 and the third-layer metal wiring (not shown) are connected by the second contact 5.
[0101]
A first insulating film 31 made of an interlayer insulating film of the present invention is formed between the first-layer metal wirings 2 and on the first-layer metal wiring 2, and the first contact 4 is a first insulating film. It is formed on the film 31. A second insulating film 32 made of an interlayer insulating film of the present invention is formed between the second-layer metal wirings 3 and on the second-layer metal wiring 3, and the second contact 5 is a second insulating film. The film 32 is formed.
[0102]
FIG. 2B shows a multilayer wiring structure having metal wiring patterned by etching, and the first-layer metal wiring 2 and the second-layer metal wiring 3 formed on the substrate 1 are the first layer. The second-layer metal wiring 3 and the third-layer metal wiring (not shown) are connected by the second contact 5.
[0103]
A first insulating film 41 made of an interlayer insulating film of the present invention is formed between the substrate 1 and the first layer metal wiring 2, and between the first layer metal wirings 2 and between the first layer metal wirings. A second insulating film 42 made of an interlayer insulating film of the present invention is formed on 2. Between the second insulating film 42 and the second layer metal wiring 3, there is a third insulating film 43 made of the interlayer insulating film of the present invention and a fourth insulating film 44 made of the interlayer insulating film of the present invention. Is formed. A fifth insulating film 45 made of an interlayer insulating film of the present invention is formed between the second-layer metal wirings 3 and on the second-layer metal wiring 3. A sixth insulating film 46 made of the interlayer insulating film of the present invention and a seventh insulating film 47 made of the interlayer insulating film of the present invention are formed between the fifth insulating film 45 and the third layer metal wiring. Has been.
[0104]
FIG. 3A shows a multilayer wiring structure having embedded metal wiring, in which a first-layer metal wiring 2 and a second-layer metal wiring 3 formed on a substrate 1 are connected by a contact 4. Has been.
[0105]
The first layer metal wiring 2 is buried in the first insulating film 51 made of the interlayer insulating film of the present invention. A second insulating film 52 made of a silicon oxide film is formed between the first-layer metal wiring 2 and the second-layer metal wiring 3, and the contact 4 is formed on the second insulating film 52. The second layer metal wiring 3 is embedded in a third insulating film 53 made of the interlayer insulating film of the present invention.
[0106]
FIG. 3B shows a multilayer wiring structure having embedded metal wiring, and the first-layer metal wiring 2 and the second-layer metal wiring 3 formed on the substrate 1 are connected by a contact 4. Has been.
[0107]
The first layer metal wiring 2 is embedded in the first insulating film 61 made of the interlayer insulating film of the present invention and the second insulating film 62 made of the silicon oxide film. A third insulating film 63 made of an interlayer insulating film and a fourth insulating film 64 made of a silicon oxide film are formed between the first layer metal wiring 2 and the second layer metal wiring 3. The contacts 4 are formed on the third insulating film 63 and the fourth insulating film 64. The second-layer metal wiring 3 is embedded in a fifth insulating film 65 made of an interlayer insulating film of the present invention and a sixth insulating film 66 made of a silicon oxide film.
[0108]
FIG. 3C shows a multilayer wiring structure having a buried type metal wiring. The first layer metal wiring 2 and the second layer metal wiring 3 formed on the substrate 1 are connected by a contact 4. Has been.
[0109]
The first layer metal wiring 2 is embedded in a first insulating film 71 made of an interlayer insulating film of the present invention and a second insulating film 72 made of a silicon oxide film. A third insulating film 73 made of a silicon oxide film is formed between the first-layer metal wiring 2 and the second-layer metal wiring 3, and the contact 4 is formed in the third insulating film 73. The second layer metal wiring 3 is embedded in a fourth insulating film 74 made of an interlayer insulating film of the present invention and a fifth insulating film 75 made of a silicon oxide film.
[0110]
FIG. 4A shows a multilayer wiring structure having a buried type metal wiring. A first layer metal wiring 2 and a second layer metal wiring 3 formed on the substrate 1 are connected by a contact 4. Has been.
[0111]
The first-layer metal wiring 2 is embedded in the first insulating film 81 made of the interlayer insulating film of the present invention. A second insulating film 82 made of the interlayer insulating film of the present invention is formed between the first layer metal wiring 2 and the second layer metal wiring 3, and the contact 4 is formed on the second insulating film 82. ing. The second-layer metal wiring 3 is embedded in a third insulating film 83 made of the interlayer insulating film of the present invention.
[0112]
FIG. 4B shows a multilayer wiring structure having a buried type metal wiring, and the first layer metal wiring 2 and the second layer metal wiring 3 formed on the substrate 1 are connected by a contact 4. Has been.
[0113]
The first layer metal wiring 2 is embedded in the first insulating film 91 made of the interlayer insulating film of the present invention and the second insulating film 92 made of the silicon oxide film. The contact 4 is embedded in a third insulating film 93 made of an interlayer insulating film of the present invention, and the second-layer metal wiring 3 is embedded in a third insulating film 93 and a fourth insulating film 94 made of a silicon oxide film. It is.
[0114]
【The invention's effect】
According to the method for forming the first interlayer insulating film, the organic component of the organoalkoxysilane is effectively taken into the organic-inorganic hybrid film, so that the generation of silanol groups is suppressed and the exhaust gas phenomenon can be suppressed, resulting in high heat resistance. In addition, an interlayer insulating film with low hygroscopicity can be formed.
[0115]
According to the method for forming the second interlayer insulating film, the organic component of the organosilicon compound is effectively taken into the organic-inorganic hybrid film, the generation of silanol groups is suppressed, and the exhaust gas phenomenon can be suppressed. An interlayer insulating film with low hygroscopicity can be formed.
[0116]
According to the third method for forming an interlayer insulating film, the organic silicon compound contains a relatively large amount of organic groups, so that the relative dielectric constant is low and the Si—O bond contained in the organic alkoxysilane is relative. Therefore, an advantage that the adhesiveness is high and the mechanical strength is high can be obtained, so that an interlayer insulating film having a low relative dielectric constant and high adhesiveness and mechanical strength can be formed.
[0117]
In the first, second, or third interlayer insulating film formation method, when the organic / inorganic hybrid film is subjected to heat treatment, the volatile organic component remaining in the organic / inorganic hybrid film is volatilized. Since the porous structure and the density of the film are reduced, the relative dielectric constant of the interlayer insulating film is further reduced.
[0118]
In the first, second, or third interlayer insulating film forming method, when the plasma treatment is performed on the organic / inorganic hybrid film, the volatile organic component remaining in the organic / inorganic hybrid film is volatilized. As the film becomes more porous and lower in density, the relative dielectric constant of the interlayer insulating film is further reduced.
[0119]
The organoalkoxysilane in the first or third interlayer insulating film forming method has the general formula: R¹Si (OR²)_Three(However, R¹Is an alkyl group, an allyl group or an aryl group, and R²Are the same or different and are an alkyl group, an allyl group or an aryl group. ), The content of the alkoxyl group in the organoalkoxysilane increases, and the formation of the siloxane skeleton is promoted, so that the thermal stability and mechanical strength of the interlayer insulating film are improved.
[0120]
The organoalkoxysilane in the first or third interlayer insulating film forming method has the general formula: R¹ ₂Si (OR²)₂(However, R¹Are the same or different and are an alkyl group, an allyl group or an aryl group, and R²Are the same or different and are an alkyl group, an allyl group or an aryl group. ), Since the organic group content in the organic alkoxysilane is relatively high, the organic component content in the organic-inorganic hybrid film is increased, so that the relative dielectric constant of the interlayer insulating film is reduced.
[0121]
The organoalkoxysilane in the first or third interlayer insulating film forming method has the general formula: R¹ _ThreeSi (OR²(However, R¹Are the same or different and are an alkyl group, an allyl group or an aryl group, and R²Is an alkyl group, an allyl group or an aryl group. ), The organic group content in the organic alkoxysilane is extremely high, and the organic component content in the organic-inorganic hybrid film is greatly increased, so that the relative dielectric constant of the interlayer insulating film is further reduced.
[0122]
The organoalkoxysilane in the first or third interlayer insulating film forming method is represented by the general formula: R¹Si (OR²)_Three(However, R¹Is an alkyl group, an allyl group or an aryl group, and R²Are the same or different and are an alkyl group, an allyl group or an aryl group. A first organic alkoxysilane represented by the general formula: R¹ ₂Si (OR²)₂(However, R¹Are the same or different and are an alkyl group, an allyl group or an aryl group, and R²Are the same or different and are an alkyl group, an allyl group or an aryl group. And a second organic alkoxysilane represented by the general formula: R¹ _ThreeSi (OR²(However, R¹Are the same or different and are an alkyl group, an allyl group or an aryl group, and R²Is an alkyl group, an allyl group or an aryl group. Or a mixture of at least two of the third organoalkoxysilanes represented by the formula (1): advantages when plasma polymerizing the first organoalkoxysilane, advantages when plasma polymerizing the second organoalkoxysilane, or An interlayer insulating film in which the advantages of plasma polymerization of the third organoalkoxysilane are combined can be formed.
[0123]
When the organic silicon compound in the second interlayer insulating film forming method is hexamethyldisiloxane, hexaphenyldisiloxane, hexamethyldisilazane or hexaphenyldisilazane, the interlayer insulating film has high heat resistance and low hygroscopicity. Can be reliably formed.
[0124]
In the first, second or third interlayer insulating film formation method, when plasma polymerization is performed in a non-oxidizing atmosphere substantially free of an oxidant, the generation of silanol groups is further suppressed, so that heat resistance It is possible to form an interlayer insulating film having a higher thickness and lower hygroscopicity.
[0125]
In the first, second or third interlayer insulating film forming method, the organic-inorganic hybrid film formed by performing plasma polymerization at a temperature of 300 ° C. or lower is higher by 100 ° C. than the temperature of plasma polymerization. When heat treatment is performed at a temperature, the volatile organic component generated by plasma decomposition remains in the organic-inorganic hybrid film, and the remaining volatile organic component is volatilized by the subsequent heat treatment. Therefore, the relative dielectric constant of the interlayer insulating film is further lowered.
[0126]
In this case, if the heat treatment after the film formation is performed in a reducing atmosphere, volatilization of the organic components remaining in the organic-inorganic hybrid film can be promoted, and the organic-inorganic hybrid film can be made more porous. The relative dielectric constant of the insulating film can be further reduced.
[0127]
In the first, second, or third interlayer insulating film forming method, the organic-inorganic hybrid film formed by performing plasma polymerization at a temperature of 350 ° C. or lower is higher by 50 ° C. than the temperature of plasma polymerization. When heat treatment is performed at a temperature, volatile organic components generated by plasma decomposition remain in the organic-inorganic hybrid film, and the remaining volatile organic components are volatilized by the subsequent plasma treatment. As the quality and density decrease, the relative dielectric constant of the interlayer insulating film is further reduced.
[0128]
In this case, if the plasma treatment after the film formation is performed in a reducing atmosphere, volatilization of the organic component remaining in the organic-inorganic hybrid film can be promoted, and the organic-inorganic hybrid film can be further made porous. The relative dielectric constant of the interlayer insulating film can be further reduced.
[Brief description of the drawings]
FIGS. 1A and 1B are cross-sectional views showing a multilayer wiring structure in which an interlayer insulating film formed by the method of the present invention is used.
FIGS. 2A and 2B are cross-sectional views showing a multilayer wiring structure in which an interlayer insulating film formed by the method of the present invention is used.
3A to 3C are cross-sectional views showing a multilayer wiring structure in which an interlayer insulating film formed by the method of the present invention is used.
4A and 4B are cross-sectional views showing a multilayer wiring structure in which an interlayer insulating film formed by the method of the present invention is used.
[Explanation of symbols]
1 Substrate
2 1st layer metal wiring
3 Second layer metal wiring
4 First contact (contact)
5 Second contact
11, 21, 31, 41, 51, 61, 71, 81, 91 First insulating film
12, 22, 32, 42, 52, 62, 72, 82, 92 Second insulating film
13, 23, 43, 53, 63, 73, 83, 93 Third insulating film
14, 24, 44, 64, 74, 94 Fourth insulating film
45, 65, 75 Fifth insulating film
46, 66, sixth insulating film
47, seventh insulating film

Claims (16)

A method of forming an interlayer insulating film comprising a step of plasma-polymerizing an organic silicon compound having a Si-O-Si bond or Si-N-Si bond to form an interlayer insulating film made of an organic-inorganic hybrid film,
Step, a method for forming an interlayer insulating film which comprises a step of forming the interlayer insulating film by performing heat treatment on the organic-inorganic Hariburiddo film for forming the interlayer insulating film. A method of forming an interlayer insulating film comprising a step of plasma-polymerizing an organic silicon compound having a Si-O-Si bond or Si-N-Si bond to form an interlayer insulating film made of an organic-inorganic hybrid film,
Step, a method for forming an interlayer insulating film which comprises a step of forming the interlayer insulating film by performing plasma treatment on the organic-inorganic Hariburiddo film for forming the interlayer insulating film. 3. The method for forming an interlayer insulating film according to claim 1, wherein the organic silicon compound is hexamethyldisiloxane, hexaphenyldisiloxane, hexamethyldisilazane, or hexaphenyldisilazane.   Interlayer insulation comprising an organic-inorganic hybrid film by plasma polymerization of a mixture of an organic silicon compound having a Si-O-Si bond or Si-N-Si bond and an alkoxy group and an organic alkoxysilane having an organic group bonded to silicon. A method for forming an interlayer insulating film, comprising forming a film. 5. The method for forming an interlayer insulating film according to claim 4 , wherein the interlayer insulating film is formed by performing a heat treatment on the organic / inorganic hybrid film. 5. The method for forming an interlayer insulating film according to claim 4 , wherein the organic / inorganic hybrid film is subjected to plasma treatment to form an interlayer insulating film. The organic alkoxysilane has a general formula: R ¹ Si (OR ² ) ₃ (where R ¹ is an alkyl group, an allyl group or an aryl group, and R ² is the same or different, and is an alkyl group or an allyl group) Or an aryl group.) The method for forming an interlayer insulating film according to claim 4 , wherein The organoalkoxysilane has a general formula: R ¹ ₂ Si (OR ² ) ₂ (wherein R ¹ is the same or different and is an alkyl group, an allyl group or an aryl group, and R ² is the same or different. It is an alkyl group, an allyl group, or an aryl group.] The method for forming an interlayer insulating film according to any one of claims 4 to 6 , The organic alkoxysilane has a general formula: R ¹ ₃ Si (OR ² ) (where R ¹ is the same or different and is an alkyl group, an allyl group or an aryl group, and R ² is an alkyl group or an allyl group) Or an aryl group.) The method for forming an interlayer insulating film according to claim 4 , wherein The organic alkoxysilane has a general formula: R ¹ Si (OR ² ) ₃ (where R ¹ is an alkyl group, an allyl group or an aryl group, and R ² is the same or different, and is an alkyl group or an allyl group) Or an aryl group.) A first organic alkoxysilane represented by the general formula: R ¹ ₂ Si (OR ² ) ₂ (wherein R ¹ is the same or different and is an alkyl group, an allyl group or an aryl group) a group, R ² are the same or different, an alkyl group, second organoalkoxysilane represented by an allyl group or an aryl group), and the general _{^{formula:. R 1 3 Si (oR}} 2) ( Wherein R ¹ is the same or different and is an alkyl group, an allyl group or an aryl group, and R ² is an alkyl group, an allyl group or an aryl group). A mixture of at least two of The method for forming an interlayer insulating film according to any one of claims 4 to 6, wherein: The method for forming an interlayer insulating film according to claim 1 , wherein the plasma polymerization is performed in a non-oxidizing atmosphere substantially free of an oxidizing agent. 6. The interlayer insulating film according to claim 1, wherein the plasma polymerization is performed at a temperature of 300 ° C. or less, and the heat treatment is performed at a temperature that is 100 ° C. or more higher than a temperature at which the plasma polymerization is performed. Forming method. The method for forming an interlayer insulating film according to claim 12 , wherein the heat treatment is performed in a reducing atmosphere. 7. The interlayer insulating film according to claim 2, wherein the plasma polymerization is performed at a temperature of 350 ° C. or lower, and the plasma treatment is performed at a temperature higher by 50 ° C. than a temperature at which the plasma polymerization is performed. Forming method. The method of forming an interlayer insulating film according to claim 14 , wherein the plasma treatment is performed in a reducing atmosphere. An interlayer insulating film forming method for forming an interlayer insulating film composed of an organic-inorganic hybrid film by plasma polymerization of an alkoxy group and an organic alkoxysilane having an organic group bonded to silicon,
The organic alkoxysilane has a general formula: R ¹ Si (OR ² ) ₃ (where R ¹ is an alkyl group, an allyl group or an aryl group, and R ² is the same or different, and is an alkyl group or an allyl group) Or an aryl group.) A first organic alkoxysilane represented by the general formula: R ¹ ₂ Si (OR ² ) ₂ (wherein R ¹ is the same or different and is an alkyl group, an allyl group or an aryl group) a group, R ² are the same or different, an alkyl group, second organoalkoxysilane represented by an allyl group or an aryl group), and the general _{^{formula:. R 1 3 Si (oR}} 2) ( Wherein R ¹ is the same or different and is an alkyl group, an allyl group or an aryl group, and R ² is an alkyl group, an allyl group or an aryl group). A mixture of at least two of A method for forming an interlayer insulating film, wherein

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