JP2000319400A - Low dielectric constant material and production of interlaminar insulation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject material which can express excellent heat resistance and adhesivity and form interlaminar insulation films having low dielectric constants and low moisture absorbability and used for semiconductor boards, by using a silicon-based polymer containing a carborane. SOLUTION: This low dielectric constant material comprises a carborane- containing silicon-based polymer which has in the molecule at least one of structural units of formula I (R1 is H, a 1 to 20C alkyl or the like; R3 is a 1 to 20C alkylene or the like) and the like and structural units of formula II [R2 is the same as R1; (n) is a natural number of 1 to 20], and has a weight- average mol.wt. of 1,000 to 5,000,000. The silicon-based polymer can be obtained, for example, by reacting a specific silicon-based polymer containing a hydrocarbon groups and double bond group-containing silylene groups with a specific bissilylcarborane derivative and a siloxane compound containing hydroxyl groups at both the terminals. An interlaminar insulation film can be obtained by dissolving the low dielectric constant material in a solvent, coating a substrate with the solution, drying the coated solution, and then heating the dried coating at 150 to 350 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low dielectric constant material used for forming an interlayer insulating film in a process of manufacturing a semiconductor substrate, and a method for manufacturing an interlayer insulating film using the same.

[0002]

2. Description of the Related Art Conventionally, a siloxane polymer has been used as a coating material used for flattening an interlayer insulating film in a semiconductor manufacturing process. 58-66335). However, all of these polymers have a silanol bond in the molecule and have hydrophilicity, so that moisture is adsorbed on the obtained interlayer insulating film, and there is a problem that the dielectric constant increases and cracks easily occur. .

As a measure for preventing such a problem, a method of performing a plasma treatment or the like before the etching step has been implemented, but the number of steps has been increased. Further, the plasma treatment has a disadvantage that the adhesion of the interlayer insulating film is reduced, and another step is required in order to optimize the treatment before and after the application.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, the present invention provides a low dielectric constant material for forming an interlayer insulating film for a semiconductor substrate having excellent heat resistance and adhesion, and having a low dielectric constant and low moisture absorption. An object of the present invention is to provide a method for producing a film.

[0005]

Means for Solving the Problems The low dielectric constant material of the present invention comprises a structural unit represented by the general formula (1), the general formula (2) or the general formula (3) and a general formula (4) or a general formula (4). It is characterized by comprising a carborane-containing silicon-based polymer having at least one of the structural units represented by the formula (5) in the molecule and having a weight average molecular weight of 1,000 to 5,000,000.

[0006]

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[0010]

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In the formula, R ¹ and R ² are a hydrogen atom, a carbon atom of 1
And represents an alkyl group having up to 20 or an aryl group having 6 to 30 carbon atoms, which may be the same or different. R
³ is an alkylene group having 1 to 20 carbon atoms or 6 to ³ carbon atoms
It does not have to show an arylene group of 0. When there is no R ³ , a vinyl group is directly bonded to a silicon atom. Z represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms. The positions of the two ethynylene groups with respect to the benzene ring are arbitrary. Also, CBp Hq C
Represents carborane which is a divalent cage-like boron compound, and p and q represent integers of 3 to 16. n shows the natural number of 1-20.

When the number of carbon atoms of the hydrocarbon group represented by R ^{1 to} R ³ increases, the bond tends to be broken and the heat resistance decreases when the number of aliphatic groups increases, and the solubility in a solvent increases when the number of aromatic groups increases. Because it decreases, it is limited to the above range.

The alkyl groups represented by R ¹ and R ² include, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, Undecyl group, dodecyl group,
Examples include tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl and the like.

The aryl groups represented by R ¹ and R ² include, for example, phenyl, tolyl, xylyl, biphenyl, naphthyl, anthracenyl and the like.

The alkylene group represented by R ³ includes, for example, a methylene group, an ethylene group, a propylene group,
Butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, octadecylene group, nonadecylene group, eicosylene group And the like.

Examples of the arylene group represented by R ³ include a phenylene group, a tolylene group, a xylylene group, a biphenylene group, a naphthalenylene group and an anthracenylene group.

The alkyl group having 1 to 20 carbon atoms and the aryl group having 6 to 30 carbon atoms represented by Z are the same as those described above for R ¹ , R
^{And the same} as the alkyl group and the aryl group represented by ² .

Examples of the carborane represented by CBp Hq C include dodecacarborane (P = 10), decacarborane (P = 8), heptacarborane (P = 5),
Hexacarborane (P = 4), pentacarborane (P =
3) and the like.

The above R ¹ , R ² , R ³ , and Z each represent the same hydrocarbon group in the following, and the above CBp Hq C represents the same carborane in the following.

In the silicon-based polymer used in the present invention, the moldability is reduced even if the molar ratio of the structural unit represented by the general formula (1) is reduced or increased.
80 mol% is preferred. In addition, general formulas (2) and (3)
When the molar ratio of the carborane-containing structural unit represented by the formula (1) is small, sufficient heat resistance and low dielectric constant cannot be obtained, and when the molar ratio is large, the moldability decreases. Furthermore, since the moldability decreases even if the molar ratio of the structural units represented by the general formulas (4) and (5) is small or large, the molar ratio is preferably 5 to 70 mol%.

The molar ratio of the carborane-containing structural units represented by the general formulas (2) and (3) is arbitrary, but if the molar ratio of the structural unit (2) is too small, sufficient moldability cannot be obtained. The molar ratio of the two is preferably in a range satisfying the following expression. 0.2 <structural unit (2) / [structural unit (2) + structural unit (3)] <0.9

The molar ratio of the structural units represented by the general formulas (4) and (5) is arbitrary, but if the molar ratio of the structural unit (4) is too small, sufficient moldability cannot be obtained.
The molar ratio of the two is preferably in a range satisfying the following expression. 0.2 <Structural unit (4) / [Structural unit (4) + Structural unit (5)] <0.9

If the weight-average molecular weight of the silicon-based polymer is too small, sufficient strength cannot be obtained, and
If it is larger than 0, on the other hand, if it is larger, the solubility in the solvent is reduced and coating becomes difficult, so it is limited to 5,000,000 or less.

The method for producing the silicon-based polymer is not particularly limited. For example, a hydrocarbon group represented by the general formula (6) or a silylene group containing a double bond group represented by the general formula (7) may be used. By reacting a silicon-containing polymer, a bissilylcarborane derivative represented by the general formula (8), and a siloxane compound having a hydrosilyl group at both terminals represented by the general formula (9). .

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Examples of the hydrocarbon group represented by the general formula (6) include 1,3-diethynylbenzene, 1,4
-Diethynylbenzene and the like. Examples of the double bond group-containing silylene group represented by the general formula (7) include methylvinylsilylene, phenylvinylsilylene, methylallylsilylene, and phenylarylsilylene.

Examples of the bissilylcarborane derivative represented by the general formula (8) include bis (dimethylsilyl) carborane, bis (diphenylsilyl) carborane, bis (methylphenylsilyl) carborane and the like. Examples of the siloxane compound having a hydrosilyl group at both terminals represented by the general formula (9) include 1,1,3,3-tetramethyldisiloxane,
1,1,3,3-tetraphenyldisiloxane, 1,
1,3,3,5,5-hexamethyltrisiloxane,
1,1,3,3,5,5-hexaphenyltrisiloxane and the like.

Examples of the catalyst used in the reaction, for example, ₂ O chloroplatinic acid [H ₂ PtCl ₅ · 6H), hexa rhodium hexadecanol carbonyl, bis (divinyltetramethyldisiloxane) platinum {Pt [CH ₂ = CHSi (CH ₃ ) ₂ OSi (C
H ₃ ) ₂ CH = CH ₂ ] ₂ ｝.

When the amount of the catalyst used is small, the reaction does not proceed sufficiently, and when the amount is large, the catalyst tends to remain in the polymer after synthesis and the heat resistance is lowered. 0.001 to 20 mol% is preferable,
More preferably, it is 0.01 to 10 mol%.

The solvent used in the above reaction may be either polar or non-polar, but is preferably an aprotic solvent such as toluene or tetrahydrofuran. The amount of the solvent used is 0.01 to 5 in terms of the concentration of the structural unit of the silicon-based polymer.
It is preferably 0 mol / L (liter), more preferably 0.05 to 5 mol / L.

The above reaction is carried out at a temperature between room temperature and the boiling point of the solvent. This reaction can be carried out either in air or under an inert gas atmosphere, but preferably under an argon gas or nitrogen gas atmosphere. If the reaction time of the above reaction is too short, the heat resistance does not improve because the introduction reaction of carborane does not proceed sufficiently, and conversely, if it is too long, the crosslinking reaction will not proceed and will not be dissolved in the solvent, making handling difficult. 1 to 72 hours are preferred.

After completion of the synthesis reaction, the resulting carborane-containing silicon-based polymer may be purified by a reprecipitation method or gel permeation chromatography (GPC).
And the like.

In the present invention, the above-mentioned carborane-containing silicon-based polymer is dissolved in a solvent, applied on a semiconductor substrate, dried, and then heated at 150 to 350 ° C. to form a coating film. A low dielectric constant interlayer insulating film is formed on a semiconductor substrate. The solvent is removed by the above drying. The heating temperature is preferably 150 to 150 to form a strong and low-dielectric interlayer insulating film having high adhesion and by crosslinking vinyl groups and ethynylene groups of the carborane-containing silicon-based polymer.
Limited to 350 ° C.

As the solvent, for example, benzene, toluene, xylene, dichlorobenzene, tetrahydrofuran, N-methylpyrrolidone and the like are used, and these may be used alone or in combination of two or more.
In addition, alcohols, glycol ethers, and the like may be used in combination with the solvent in order to improve fluidity and coatability.

As a method of dissolving the above-mentioned carborane silicon-based polymer in a solvent, and applying it on a substrate such as glass, ceramic, a silicon wafer, or a silicon wafer having a circuit formed thereon, for example, a dipping method, a spin coating method, etc. A known method is used.

(Operation) In general, a low dielectric constant material is obtained by using small and light atoms to have a low density. The low dielectric constant material of the present invention is characterized in that boron uses carborane having a cage-like molecular structure. Boron is a light atom, and its cage-like molecular structure can reduce the density. Furthermore, by forming a composite with a silicon-based polymer, high heat resistance and adhesion can be exhibited.

[0040]

Embodiments of the present invention will be described below.

(Example) 50 with a reflux tube replaced with argon
In a 0 ml four-necked flask, 10.26 g of poly (1,3-diethynylbenzene / phenylvinylsilylene) (4
0.0 mmol) and dissolved in 250 ml of toluene. After the temperature of the reaction solution was raised to 50 ° C., 0.20 mmol
l of catalyst bis (divinyltetramethyldisiloxane) platinum in toluene was added and stirred for 10 minutes. Then
1,7-bis (dimersilyl) dodecacarborane 5.2
80 g of a toluene solution of 1 g (20.0 mmol) and 1.35 g (10.03 mmol) of 1,1,3,3-tetramethyldisiloxane was added dropwise.
The temperature was raised to 25 ° C., and the mixture was heated under reflux for 7 hours. Further, the reaction solution was distilled off under reduced pressure, and then poured into 1.7 L of methanol. The resulting precipitate was filtered off and a yellow-white polymer (powder) 1
3.46 g were obtained. The weight average molecular weight of this polymer was 27,700 in terms of polystyrene.

FIG. 1 shows the ¹ H-NMR spectrum (measured by “DRX300” manufactured by Bruker) of the above polymer, and the IR spectrum (“FTS135 system” manufactured by Bio-Rad) was obtained.
Are shown in FIG.

In FIG. 1, the peak of the proton based on carborane is from 0.7 to 4 ppm, 0 to 0.6 pp.
A peak of a proton based on a methyl group and a methylene group bonded to a silicon atom over m, a peak of a proton based on a phenyl group over 7 to 8 ppm, and a peak of a proton based on a vinyl group over 6 to 6.5 ppm were respectively confirmed. 2, absorption was observed due to the carborane to 2594cm ^-1, absorption is observed due to the siloxane bond in the vicinity of 1050 cm ^-1. From these, it was confirmed that the polymer of Example 1 had a structure of the general formula (10) and was a carborane-containing silicon-based polymer.

[0044]

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After dissolving the silicon-based polymer in tetrahydrofuran, the solution was dropped on a substrate on which aluminum was deposited, and a 1 μm thick film was formed by spin coating. After drying at room temperature, the resultant was placed in an oven at 250 ° C. and thermally crosslinked to form a strong insulating film. Next, after applying a silver paste on the insulating film, the dielectric constant between the insulating film and the aluminum base layer was 2.7 at a frequency of 1 MHz. This value is sufficiently lower than the existing low dielectric film. Next, in order to evaluate the durability test of this insulating film, a test was performed for 100 hours in a pressure cooker at 121 ° C., 2 atm, and 85% RH, but no crack or peeling was observed.

(Comparative Example) A conventionally used organosilsesquioxane polymer was dropped on a substrate on which aluminum was deposited, and spin-coated at 1 μm.
After forming a thick film, heat treatment was performed at 200 ° C. to form an insulating film. When the dielectric constant of the insulating film was measured in the same manner as in the example, it was 2.7 at a frequency of 1 MHz.
Next, when the same durability test as that of the example was performed on the insulating film, cracks and peeling were observed on the entire surface.

[0047]

The low dielectric material of the present invention has the above-mentioned structure, and is excellent in heat resistance, adhesion to a semiconductor substrate, low dielectric constant and low by using a silicon-based polymer containing carborane. Has hygroscopicity. Therefore, by using the low dielectric material of the present invention, a low dielectric constant interlayer insulating film can be formed on a semiconductor circuit board, and a high-speed semiconductor circuit board can be produced.

[Brief description of the drawings]

FIG. 1 shows a ¹ H-NMR spectrum of a silicon-based polymer of an example.

FIG. 2 shows an IR spectrum of a silicon-based polymer of an example.

Claims (2)

[Claims] 1. A structural unit represented by the general formula (1), (2) or (3) and / or a structural unit represented by the general formula (4) or (5) A low dielectric constant material comprising a carborane-containing silicon-based polymer having in the molecule a weight average molecular weight of 1,000 to 5,000,000. Embedded image Embedded image Embedded image Embedded image Embedded image (Wherein, R ^1, R ² is a hydrogen atom, an alkyl group or an aryl group having 6 to 30 carbon atoms having 1 to 20 carbon atoms, optionally .R ³ be different even respectively identical, It does not have to be an alkylene group having 1 to 20 carbon atoms or an arylene group having 6 to 30 carbon atoms.In the absence of R ³ , a vinyl group is directly bonded to a silicon atom.
Z represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms. The positions of the two ethynylene groups with respect to the benzene ring are arbitrary. CBp Hq C represents carborane which is a divalent cage-like boron compound, and p, q
Represents an integer of 3 to 16. n represents a natural number of 1 to 20) 2. The low dielectric constant material according to claim 1, which is dissolved in a solvent, applied to a substrate and dried, and then heated to 150 to 350 ° C.
A method of manufacturing an interlayer insulating film, characterized by heating the substrate.