JP2005200515A - Material for forming insulating film and insulating film using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material for forming an insulating film, which is capable of forming a coating film, as an interlayer insulating film for a semiconductor element and the like, uniform in thickness, excellent in heat resistance, less liable to generate cracks and excellent in dielectric characteristics. <P>SOLUTION: The material for forming the insulating film contains a polymer (A) having a repeating unit represented by formula (I). In formula (I) R<SB>1</SB>-R<SB>7</SB>indicate each a hydroxyl group, hydrocarbon group, group that turns into a hydrocarbon group by the Diels-Alder reaction, a group obtained by replacing part of the carbon atoms of the hydrocarbon group with silicon atom, or a group obtained by replacing part of the carbon atoms of the group that turns into a hydrocarbon group by the Diels-Alder with silicon atom; one of X, Y, and Z indicates a hydroxyl group and the remaining two are different and selected from -O- and formula (IB) that is linked at the side of the oxygen atom; and n indicates 1-10. In formula (IB) R<SB>11</SB>-R<SB>14</SB>are the same as defined in R<SB>1</SB>-R<SB>7</SB>; R<SB>15</SB>-R<SB>17</SB>indicate each a single bond, a hydrocarbon group or a group that turns into a hydrocarbon group by the Diels-Alder reaction; R<SB>18</SB>indicates a single bond or -O-; and m indicates 0-10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an insulating film forming material, and more specifically, as an interlayer insulating film material in a semiconductor element or the like, a coating film having an appropriate uniform thickness can be formed, and cracks are hardly generated, and dielectric constant characteristics, etc. The present invention relates to an excellent insulating film forming material.

Conventionally, a silica (SiO ₂ ) film formed by a vacuum process such as a CVD method is often used as an interlayer insulating film in a semiconductor element or the like. In recent years, for the purpose of forming a more uniform interlayer insulating film, a coating type insulating film called a SOG (Spin on Glass) film containing a hydrolysis product of tetraalkoxysilane as a main component has been used. It has become. Further, with the high integration of semiconductor elements and the like, a low dielectric constant interlayer insulating film called polyorganosiloxane called organic SOG has been developed for the purpose of solving the problem of wiring delay.

However, it is a CVD-SiO ₂ film showing the lowest dielectric constant among the inorganic material films, and has a relative dielectric constant (hereinafter simply referred to as “dielectric constant”) of about 4. The SiOF film, which has been recently studied as a low dielectric constant CVD film, has a dielectric constant of about 3.3 to 3.5. This film has high hygroscopicity, and the dielectric constant increases while being used. There is a problem of doing.

On the other hand, an organic polymer film having a low dielectric constant of 2.5 to 3.0 has a low glass transition temperature of 200 to 350 ° C. and a high coefficient of thermal expansion. ing. In addition, the organic SOG film has a drawback that it is oxidized by oxygen plasma ashing used for resist stripping or the like when forming a multilayer wiring pattern, and cracks are generated.
In addition, since an organic resin containing organic SOG has low adhesion to aluminum and aluminum-based alloys, and copper and copper-based alloys, which are wiring materials, a void (wiring and insulating material and Between the wiring layers when misalignment occurs when opening a via hole for forming a multi-layer wiring. There is a problem in that the short circuit is caused and the reliability is lowered.

Under such circumstances, as an insulating film material excellent in insulation, heat resistance, and durability, an organopolysiloxane having a cage structure, specifically, a copolymer containing hydrogenated octasilsesquioxane is contained. A coating-type composition for forming an insulating film is known (see Patent Document 1 and Patent Document 2). Further, Patent Document 3, an insulating film-forming coating type composition containing siloxane T ₈ cage structure (silsesquioxane) are described, the low-density insulating film polymerized by crosslinking It is described that a reduction in dielectric constant can be achieved by forming.

JP 2000-265065 A JP 2000-265066 A Japanese Patent Laid-Open No. 11-40554

However, with higher integration and multi-layering of semiconductor devices and the like, better electrical insulation between conductors is required, and there is a need for an interlayer insulation film material with lower dielectric constant, crack resistance and heat resistance. It is supposed to be. The insulating film forming material containing polysiloxane (polysilsesquioxane) having a known cage structure as described above still has insufficient heat resistance, crack resistance and dielectric constant characteristics.
Accordingly, an object of the present invention is to provide an insulating film forming material for solving the above problems, and more specifically, a coating film having an appropriate uniform thickness as an interlayer insulating film in a semiconductor element or the like. It is an object to provide a material for forming an insulating film, which is capable of forming a film, is excellent in heat resistance, hardly cracks, and has excellent dielectric constant characteristics.
Another object of the present invention is to provide an insulating film using the insulating film forming material.

It has been found that the above object of the present invention is achieved by the following constitutions (1) to (3).
(1) An insulating film-forming material comprising a polymer (A) having a repeating unit represented by the following general formula (I).

In the general formula (I), R _{1 to} R ₇ may be the same or different and can each be a hydroxyl group, a monovalent hydrocarbon group, or a hydrocarbon group by Diels-Alder reaction and subsequent elimination reaction. A monovalent group, a group in which a carbon atom of a monovalent hydrocarbon group is partly replaced with a silicon atom, or a carbon atom of a monovalent group that can be converted into a hydrocarbon group by a Diels-Alder reaction and subsequent elimination reaction Represents a group in which a part of is replaced by a silicon atom. One of X, Y, and Z represents a hydroxyl group, and the remaining two are different from each other, and are selected from the following general formula (IB) linked on the -O- and oxygen atom side. n represents 1-10.

R _{11 to} R ₁₄ may be the same or different and have the same definition as R _{1 to} R ₇ .
R _{15 to} R ₁₇ may be the same or different and each represents a single bond or a divalent hydrocarbon group, or a divalent group that can become a hydrocarbon group by a Diels-Alder reaction and a subsequent elimination reaction.
R ₁₈ represents a single bond or —O—. m represents 0-10.
(2) Insulation according to (1), wherein in formula (I), at least one of R _{1 to} R ₁₇ satisfies at least one of the following (i) to (iii): Film forming material.
(i) It has at least one carbon-carbon triple bond.
(ii) It has at least one carbon-carbon double bond conjugated with an aromatic group or carbon-nitrogen double bond conjugated with an aromatic group.
(iii) having at least one aromatic ring having 10 or more carbon atoms.
(3) An insulating film obtained using the insulating film forming material according to (1) or (2).

As described above, the material for forming an insulating film of the present invention is characterized by containing an organopolysiloxane (polysilsesquioxane) having a specific cage structure represented by the formula (I). is there. That is, siloxane (silsesquioxane) having a T _{7 to} T ₂₅ cage structure in which R ₁ to ₁₄ of the above formula (I) of the present invention contains a specific organic group has a small space in the molecule due to the cubic structure. In addition to having a two-dimensional to three-dimensional structure and polymerizing by a crosslinking reaction by heat treatment, an insulating film having a lower density is formed, and an excellent low dielectric constant is achieved. In particular, since no hydrogen atom is contained as R _1-14 , the chemical stability is improved, an increase in the dielectric constant with time is suppressed, and the shrinkage rate is reduced so that it has an excellent effect of being hard to crack. Was found. Moreover, since it does not contain a fluorine atom, it has been found that there is no decrease in adhesion, and it is excellent in that it does not react with the metal used for the barrier metal that causes interface peeling.
Thus, since the insulating film forming material of the present invention contains an organopolysiloxane (polysilsesquioxane) having a specific cage structure, the thickness uniformity in the coating film, crack resistance, An interlayer insulating film having an excellent balance of dielectric constant characteristics and the like can be formed.

  That is, when a film forming material containing the polyorganosiloxane (polysilsesquioxane) of the present invention as a base polymer is applied to a substrate such as a silicon wafer by dipping or spin coating, for example, between fine patterns When the organic solvent is removed and the crosslinking reaction is carried out by heating, a glassy or giant polymer film or a mixture thereof can be formed. The resulting film can form a thick insulator having good heat resistance, excellent low dielectric constant, and no cracks.

Hereinafter, the resin used in the present invention, that is, the polymer (A) having a repeating unit represented by the general formula (I) will be described in detail.
As described above, the polymer (A) having a repeating unit represented by the general formula (I) (hereinafter sometimes referred to as “resin having a structure represented by the general formula (I)”) is R _1-14. As an organopolysiloxane (polysilsesquioxane) having a T _{7 to} T ₂₅ cage structure having a specific organic group. The preferred weight average molecular weight of the resin having the structure represented by the general formula (I) of the present invention is 1,000 to 10,000,000. Within this range, these organopolyethylenes can be used regardless of the molecular weight. Siloxane (polysilsesquioxane) can be used for the insulating film forming material of the present invention. The number average molecular weight of the resin having the structure represented by the formula (I) is usually about 500 to 5,000,000, preferably about 1,000 to 100,000. More preferably, it is about 2,000 to 20,000.
The insulating film forming material of the present invention contains a polymer (A) having a repeating unit represented by the general formula (I).

In the general formula (I), a plurality of R _{1 to} R ₇ may be the same or different and are each a hydroxyl group, a monovalent hydrocarbon group, an alkoxy group, or a hydrocarbon by Diels-Alder reaction and subsequent elimination reaction. A monovalent group that can be a group, a group in which some carbon atoms of a monovalent hydrocarbon group are replaced with silicon atoms, a group in which some carbon atoms in an alkoxy group are replaced with silicon atoms, or Diels-Alder A group in which a part of carbon atoms of a monovalent group that can become a hydrocarbon group by the reaction and subsequent elimination reaction is replaced with a silicon atom. n represents 1-10.
The number of hydroxyl groups in the general formula (I) is preferably 0 to 4, more preferably 0 to 1, and particularly preferably 0 per repeating unit.

Examples of the monovalent hydrocarbon group as R _{1 to} R ₇ include those represented by the following (a-1) to (a-4) and (b-1) to (b-4). . These preferably have 20 or less carbon atoms.
(A-1) Monovalent linear, branched, and cyclic saturated hydrocarbon groups (alkyl groups).
(A-2) A monovalent linear, branched or cyclic hydrocarbon group having an ethylenic carbon-carbon double bond.
(A-3) A monovalent linear, branched, or cyclic hydrocarbon group having a carbon-carbon triple bond.
(A-4) A monovalent linear, branched or cyclic hydrocarbon group having both an ethylenic carbon-carbon double bond and a carbon-carbon triple bond.
(B-1) A group in which 1 to 10 hydrogen atoms of the groups (a-1) to (a-4) are substituted with a monovalent aromatic hydrocarbon group.
(B-2) A group in which 1 to 10 of the methylene groups in the groups (a-1) to (a-4) and (b-1) are replaced with a divalent aromatic hydrocarbon group.
(B-3) 1-10 of the methine groups of the groups (a-1) to (a-4) and (b-1) to (b-2) are replaced with a trivalent aromatic hydrocarbon group. Group.
(B-4) 1 to 10 of the quaternary carbons of the groups (a-1) to (a-4) and (b-1) to (b-3) are tetravalent aromatic hydrocarbon groups. Replaced group.
In this case, the number of replacements is preferably 1 to 8, more preferably 1 to 4.

Examples of (a-1) to (a-4) include the following.
(A-1) methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, isopentyl, t-pentyl, neopentyl, cyclopentyl, n-hexyl, cyclohexyl, octyl, Spiro hydrocarbon groups such as linear, branched or cyclic alkyl groups such as nonyl, dodecyl, hexadecyl and octadecyl, bridged cyclic hydrocarbon groups (alicyclic groups) such as 1-adamantyl, and spirobicyclohexyl.
(A-2) Vinyl, allyl, isopropenyl, 1-butenyl, 2-butenyl, 2-methyl-propen-1-yl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 2-methyl-butene-1- A cyclic terpene hydrocarbon group having a double bond such as a linear, branched or cyclic alkenyl group such as yl, and 5-norbornen-2-yl.
(A-3) Alkynyl groups such as ethynyl and propargyl, alkanedienyl groups such as 1,4-hexadienyl, alkanetrienyl groups having three double bonds, alkanediynyl groups having two triple bonds, triple bonds An alkanetriinyl group having three.
(A-4) A group such as an enynyl group such as 5-ethynyl-1,3,6-heptatrienyl having both a double bond and a triple bond.
Examples of the aromatic hydrocarbon group to be substituted by (b-1) to (b-4) include the following.
Examples of the aromatic hydrocarbon group to be substituted by (b-1) include phenyl, naphthyl, anthryl, phenanthryl, pyrenyl, and the following monovalent aromatic hydrocarbon groups.

Examples of the aromatic hydrocarbon group to be substituted by (b-2) include arylene groups such as 1,4-phenylene, 2,7-phenanthrene and 4,4-bis (phenyl), and divalent aromatics shown below. A hydrocarbon group is mentioned.

Examples of the aromatic hydrocarbon group to be substituted by (b-3) include trivalent aromatic hydrocarbon groups such as 1,3,5-benzenetriyl and 1,2,6-naphthalenetriyl.
Examples of the aromatic hydrocarbon group to be substituted by (b-4) include tetravalent aromatic hydrocarbon groups such as 1,2,4,5-benzenetetrayl and 1,4,5,8-anthracenetetrayl. Can be mentioned.
Examples of (b-2) in which the carbon of (a-1) containing a cyclic hydrocarbon is substituted with one monovalent aromatic hydrocarbon group and three divalent aromatic hydrocarbon groups are shown below. Things. .

  The carbon of (a-3) having a triple bond was substituted with two monovalent aromatic hydrocarbon groups and one divalent aromatic hydrocarbon group and one trivalent aromatic hydrocarbon group ( Examples of b-3) include the following. . These are groups which can react to form another hydrocarbon group, and are preferable.

Moreover, a benzocyclobutene structure is mentioned as a structure which substituted the methylene or methine of the cyclopropane structure with the bivalent or trivalent benzene ring among (b-2) or (b-3). This is a hydrocarbon group and has a structure that reacts to become another hydrocarbon group, which is a preferable example. More specifically, the following examples are given.

As R _{1 to 7,} Diels - Examples of the monovalent group capable of being a hydrocarbon group followed by subsequent elimination reaction Alder reaction include the (c) is less.
(C) A conjugated diene having a hetero atom or a conjugated two aromatic group having a weak double bond, and performing a concerted [4 + 2] addition with a dienophile (parent diene) such as a substituted alkene or a substituted alkyne. Thereafter, the cross-linking site containing a hetero atom is eliminated to have a site that becomes a hydrocarbon group such as a benzene ring. Below, the example of the reaction format of (c) is shown.

Examples of (c) include the following.
(C-1) Cyclopentadione structure or aromatic hydrocarbon group substituted with one to three aromatic rings of (b-1) to (b-4) above with the same valence Group replaced with pentadienone structure.
(C-2) One to three aromatic rings of (b-1) to (b-4) above are replaced with a furan structure having the same valence, or a furan structure substituted with an aromatic hydrocarbon group. Group.
(C-3) One to three aromatic rings of (b-1) to (b-4) above are replaced with an oxazole structure having the same valence or an oxazole structure substituted with an aromatic hydrocarbon group Group.
Specific examples of (c-1) to (c-3) include the following.

Examples of the group in which a part of carbon atoms of the monovalent hydrocarbon group as R _{1 to 7} are replaced with silicon atoms include the following (d). These preferably have 20 or less carbon atoms.
(D) a group in which one to ten carbon atoms of the groups (a-1) to (a-4) and (b-1) to (b-4) are replaced with silicon atoms, provided that (d ) Contains at least one carbon.
In this case, replacement with silicon atoms is preferably 1 to 8, more preferably 1 to 4.
Specific examples of (d) include the following groups in addition to trimethylsilyl group and tris (trimethylsilyl) silyl group.

Examples of R _{1 to 7} include the following (e) as a group in which a part of carbon atoms of a monovalent group that can become a hydrocarbon group is replaced with a silicon atom by Diels-Alder reaction and subsequent elimination reaction.
(E) A group in which one to ten carbon atoms of the groups (c-1) to (c-3) are replaced with silicon atoms, provided that (e) contains at least one carbon.
In this case, the replacement with silicon atoms is preferably 1 to 8, more preferably 1 to 6.
Examples of (e) include the following.

R _{1 to 7} are arbitrarily selected from the above group.
In the formula (Ia), R _{8 to} R ₁₀ may be the same or different and have the same definition as R _{1 to} R ₇ and are preferably selected from the above.
In the formula (Ib), R _{11 to} R ₁₄ may be the same or different and have the same definition as R _{1 to} R ₇ and are preferably selected from the above.
Further, R _{15 to} R ₁₇ may be the same or different, and represent a single bond or a divalent hydrocarbon group, or a divalent group that can become a hydrocarbon group by a Diels-Alder reaction and a subsequent elimination reaction. Represent. This, in the definition of R ₁ to R _7, select the one containing no Si atom, which was replaced by one single bond hydrogen on the carbon, the group of preferred examples of the R ₁ to R ₇ A material that does not contain Si atoms is selected from the above, and one in which hydrogen on carbon is replaced with a single bond is preferably selected.

Furthermore, at least one condition is satisfied are preferable among the formulas at least one of R ₁ of R ₁ in (I) is the following (i) ~ (iii).
(I) It has at least one carbon-carbon triple bond.
(Ii) It has at least one carbon-carbon double bond conjugated with an aromatic group.
(Iii) It has at least one aromatic ring having 10 or more carbon atoms.
The condition (i) preferably has 1 to 8 triple bonds per T ₈ structure, and more preferably 1 to 4 triple bonds. Condition (ii) preferably has a carbon-carbon double bond conjugated with 1 to 16 aromatic groups or a carbon-nitrogen double bond conjugated with an aromatic group per T ₈ structure. . More preferably, it is 1-4. As the condition (iii), it is preferable to have 1 to 8 aromatic rings having 10 or more carbon atoms per T ₈ structure. More preferably, it is 1-2.
Among these conditions, (i) and / or (ii) are more preferable.
R ₁ is preferably selected from combinations including (a-3) to (a-4), (b-2) to (b-4), and (c-1) to (c-3), a-3), (b-2) to (b-3), and (c-1) to (c-3) are more preferably selected in combination.

  Moreover, the polymer of the (A) component used for this invention may be used independently, and 2 or more types may be mixed and used for it. The amount of the component (A) polymer used is 40 to 100% by mass, preferably 60 to 100% by mass, based on the total mass (excluding the solvent) of the insulating film forming material.

  Although the specific example of the repeating unit represented by general formula (I) which the polymer of the (A) component used for this invention has is shown below, it is not limited to these. The specific structure shown here can be synthesized by a method similar to the synthesis method described later and further by functional group conversion.

（Ｉ−１０）

(I-10)

（Ｉ-１１）

(I-11)

（I-１２）

(I-12)

（I-１３）

(I-13)

（I-１４）

(I-14)

（I-１５）

(I-15)

In the above formulas (I-11) to (I-15), R ^a represents a hydrocarbon group not containing an aromatic ring, and Ar, Ar ′ and Ar ″ represent a hydrocarbon group containing an aromatic ring. In the group containing R ^a and Ar which are substituents on Si, positions of Si substituted with each other may be exchanged. L is 0 or 1, when l is 0, m is an integer from 0 to 6, and when l is 1, m is 0.

Examples of the hydrocarbon group not containing an aromatic ring of ^Ra include a group such as (a-1). Preferred examples of Ar, Ar ′, and Ar ″ include (b-1) to (b-3), and specific examples include phenyl, naphthyl, phenylene, naphthylene, and the like.

  In the present invention, a resin other than the polymer of component (A) can be used in combination. Examples of resins that can be used in combination include ladder-type polysilsesquioxane resins, hydrolyzates and / or condensates of alkoxysilane materials, polyarylene ethers, hydrocarbon polymers, and the like.

The resin represented by the general formula (I) of the present invention is obtained by hydrolyzing and condensing a trichlorosilane mixture in which specific groups are substituted as R _{1 to} R ₇ according to a desired object under kinetic conditions. As a result, the precursor T ₇ trisilanol can be obtained and synthesized by the subsequent reaction of silanol and organochlorosilane. For example, J. Am. Chem. Soc. 1964 .86, 1120, J. Am. Chem. Soc. 1965, 87, 4313, ACS Polym. Mat. Sci. & Eng. Preprints 1998, 79, 389, J. Am Chem. Soc. 1990, 112, 1931-1936 and J. Am. Chem. Soc. 1989, 111, 1741-1748.
Further, after forming a cage structure or a further polymer structure, a substituent on a silicon atom can be substituted with a desired functional group. Examples of the reaction include hydrosilylation using a platinum catalyst. Such reaction examples are also disclosed in Patent Document 1, Patent Document 2, and the like. Moreover, a well-known coupling reaction etc. can also be used preferably.
For example, it can be synthesized as follows.

あるいは

Or

  It can also be synthesized as follows.

[Other additives]
Components such as colloidal silica, colloidal alumina, and organic polymer may be further added to the insulating film forming material of the present invention. Colloidal silica is, for example, a dispersion in which high-purity silicic acid is dispersed in a hydrophilic organic solvent (for example, methanol, ethanol, isopropanol, etc.), and the average particle size is usually 5 to 30 mμ, preferably 10 ˜20 mμ and solid content concentration is about 10 to 40% by mass. Examples of such colloidal silica include Nissan Chemical Industries, Ltd., methanol silica sol and isopropanol silica sol; Catalyst Chemical Industries, Ltd., Oscar. Examples of the colloidal alumina include Alumina Sol 520, 100 and 200 manufactured by Nissan Chemical Industries, Ltd .; Alumina Clear Sol, Alumina Sol 10 and 132 manufactured by Kawaken Fine Chemical Co., Ltd., and the like. Examples of organic polymers include compounds having a polyalkylene oxide structure, compounds having a sugar chain structure, vinylamide polymers, (meth) acrylate compounds, aromatic vinyl compounds, dendrimers, polyimides, polyamic acids, polyarylenes, polyamides, Examples thereof include polyquinoxaline, polyoxadiazole, and a fluorine-based polymer.

[Method for Preparing Film Forming Material Using Resin Containing Structure of General Formula (I)]
The film-forming material of the present invention is dissolved in a solvent that dissolves each of the above components and coated on a support. In preparing the film-forming material of the present invention, as described above, the resin having the structure of the above-mentioned formula (I) of the present invention and other components may be mixed if necessary, and the method is particularly limited. Not.

  The following solvents are suitable as the solvent used here. Ethylene dichloride, cyclohexanone, cyclopentanone, 2-heptanone, methyl isobutyl ketone, γ-butyrolactone, methyl ethyl ketone, methanol, ethanol, dimethylimidazolidinone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, 2-methoxy Ethyl acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), tetraethylene glycol dimethyl ether, triethylene glycol monobutyl ether, triethylene glycol monomethyl ether, isopropanol, ethylene carbonate, acetic acid D Butyl acetate, methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, N, N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone , Tetrahydrofuran, diisopropylbenzene, toluene, xylene, mesitylene and the like are preferable, and these solvents are used alone or in combination.

  Among these, preferable solvents include propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, 2-heptanone, cyclohexanone, γ-butyrolactone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl. Ether, propylene glycol monoethyl ether, ethylene carbonate, butyl acetate, methyl lactate, ethyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, N-methylpyrrolidone, N, N-dimethylformamide, tetrahydrofuran, methyl isobutyl ketone, xylene, Mention may be made of mesitylene and diisopropylbenzene.

The total solid concentration of the forming material of the present invention thus obtained is preferably 2 to 30% by mass, and is appropriately adjusted according to the purpose of use. When the total solid content concentration of the forming material is 2 to 30% by mass, the film thickness of the coating film is in an appropriate range, and the storage stability is further improved.
When the insulating film forming material of the present invention is applied to a substrate such as a silicon wafer, SiO ₂ wafer, or SiN wafer, a coating means such as a spin coat method, a dipping method, a roll coat method, or a spray method is used. . At this time, as a dry film thickness, a coating film having a thickness of about 0.05 to 1.5 μm can be formed by one coating, and a coating film having a thickness of about 0.1 to 3 μm can be formed by two coatings. Thereafter, it is dried at room temperature, or usually heated at a temperature of about 80 to 600 ° C. for about 5 to 240 minutes to dry, thereby forming an insulating film of vitreous or giant polymer or a hybrid thereof. be able to. The heat treatment at this time can use a hot plate, an oven, a furnace, and the like, and the heating atmosphere can be performed in the air, a nitrogen atmosphere, an argon atmosphere, a vacuum, a reduced pressure with a controlled oxygen concentration, or the like. it can.

More specifically, the insulating film forming material of the present invention is applied onto a substrate (usually a substrate having metal wiring) by, for example, spin coating, and a first heat treatment is performed at a temperature of 300 ° C. or lower. The insulating film having a low dielectric constant can be formed by drying the solvent and crosslinking a part thereof, and then performing a second heat treatment (annealing) at a temperature higher than 300 ° C. and lower than 450 ° C. The reason why the first heat treatment is set to 300 ° C. or lower is to make it easy to adjust the degree of cross-linking so that crosslinking does not proceed excessively, and the second heat treatment is set to a temperature higher than 300 ° C. and lower than 450 ° C. This is because this temperature range is generally convenient for annealing.
The first heat treatment can be performed in the air. Further, the degree of crosslinking may be adjusted in order to adjust the dielectric constant exhibited by the formed insulating film, and this degree of crosslinking can be adjusted by adjusting the heat treatment temperature and time.

  The interlayer insulating film thus obtained has excellent insulating properties, coating film uniformity, dielectric constant characteristics, coating film crack resistance, and coating film surface hardness, so that LSI, system LSI, DRAM, For applications such as interlayer insulation films for semiconductor elements such as SDRAM, RDRAM, D-RDRAM, protective films such as surface coating films for semiconductor elements, interlayer insulation films for multilayer wiring boards, protective films for liquid crystal display elements and insulation prevention films Useful.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, unless otherwise indicated, the part and% in an Example have shown that they are the mass part and the mass%, respectively. Moreover, evaluation of the film forming material in the examples was measured as follows.

[Weight average molecular weight (Mw)]
It measured by the gel permeation chromatography (GPC) method by the following conditions.
<Sample> Tetrahydrofuran was used as a solvent, and 0.01 g of a sample was prepared by dissolving in 2 cc of tetrahydrofuran.
<Standard polystyrene> Standard polystyrene TSK standard manufactured by Tosoh Corporation was used.
<Apparatus> High speed gel permeation chromatogram (HLC-8220GPC) manufactured by Tosoh Corporation
<Column> TSK-gel (GMX) manufactured by Tosoh Corporation
<Measurement temperature> 40 ° C. Flow rate: 1 cc / min

[In-plane uniformity]
The film-forming material was applied on a 6-inch silicon wafer using a spin coater under the conditions of a rotational speed of 1,500 to 2,500 rpm for 20 seconds. Thereafter, using a hot plate maintained at a temperature of 80 ° C., the silicon wafer coated with the film forming material was heated for 5 minutes to scatter the organic solvent. Next, using a hot plate maintained at a temperature of 200 ° C., the silicon wafer coated with the film forming material was heated for 5 minutes to form a coating film on the silicon wafer. The film thickness of the coating film thus obtained was measured at 50 points within the coating film surface using an optical film thickness meter (Dainippon Screen, Lambda Ace). 3σ of the obtained film thickness was calculated and evaluated according to the following criteria.
○: 3σ of coating film is less than 80 nm ×: 3σ of coating film is 80 nm or more

[Crack resistance]
A film-forming material is applied onto a 6-inch silicon wafer by spin coating, the substrate is dried on a hot plate at 80 ° C. for 5 minutes and at 200 ° C. for 5 minutes, and further in an oven at 450 ° C. in a nitrogen atmosphere. The substrate was baked for 60 minutes. The appearance of the obtained coating film was observed with a pocket micro loupe (50 times) manufactured by Peak Corporation, and evaluated according to the following criteria. Further, PCT (JDEC JESD22-A102-B condition: 121 ° C., 100% RH, 15 psig) was performed for 96 hours, and evaluation was performed according to the same criteria.
○: No cracks are observed on the coating surface.
X: Cracks are observed on the coating film surface.

[Dielectric constant]
A film-forming material is applied onto a 6-inch silicon wafer by spin coating, the substrate is dried on a hot plate at 80 ° C. for 5 minutes and at 200 ° C. for 5 minutes, and further in an oven at 450 ° C. in a nitrogen atmosphere. The substrate was baked for 60 minutes. For the obtained film-coated substrate, the capacitance was measured using Cvmap92 manufactured by Four Dimensions Inc. as the electrode and HP4285A manufactured by Hewlett-Packard Co. as the LCR meter, and from this value and the film thickness separately obtained by spectroscopic ellipsometry The relative dielectric constant was determined.
It was calculated from the capacity value at 100 kHz. Further, PCT (JDEC JESD22-A102-B condition: 121 ° C., 100% RH, 15 psig) was performed for 96 hours, and then measurement and calculation were performed.

Synthesis Example 1 <Synthesis of Polymer (I-10)>
(1) Synthesis of trisilanol compound 50 g of vinyltriethoxysilane was dissolved in 920 ml of acetone. To this solution, 250 ml of distilled water was gradually added at room temperature, and then reacted at room temperature for 2 weeks. The resulting solution was concentrated at room temperature, extracted with toluene, washed with water, and dried to obtain 30 g of a solid. The weight average molecular weight was 1000.

(2) Synthesis of polymer 7.0 g of trisilanol obtained by the synthesis of (1) was dissolved in 110 ml of THF, and 3.0 g of triethylamine was further added. To this solution, 1.50 g of 1,3-dichlorotetramethyldisiloxane was added dropwise with stirring and reacted at room temperature for 5 hours and further at 60 ° C. for 6 hours. The reaction mixture was poured into 2.0 liters of ultrapure water to precipitate a powder. The obtained resin was dried in a vacuum dryer at 120 ° C. for 12 hours to obtain a polymer (I-10). The obtained polymer (I-10) had a weight average molecular weight (Mw) of 11,000.

Synthesis example 2
A resin was obtained in the same manner as in Synthesis Example 1 using 30 g of a mixture of ethyltrichlorosilane / 4-bromophenyltrichlorosilane in a molar ratio of 5/2. Subsequently, a terminal tin salt of phenylacetylene equivalent to the intermediate was dissolved in THF, and a compound having a triple bond was obtained by a coupling reaction using zerovalent palladium as a catalyst. A solid obtained by processing in a conventional manner was purified by chromatogram to obtain Sample A-1 (20 g: Mw 8,000).

  A sample (A-2: Mw 7,000) was synthesized in the same manner.

Example 1
A solution prepared by dissolving 5 g of the sample (A-1) obtained in Synthesis Example 2 in 45 g of a mixed solvent of diisopropylbenzene / cyclohexanone / propylene glycol monomethyl ether was filtered through a Teflon (registered trademark) filter having a 0.2 μm pore size, and spin It apply | coated on the silicon wafer with the coating method. The film thickness of the obtained coating film was 680 nm, and 3σ was as good as 25 nm. When the maximum film thickness at which cracks did not occur was evaluated by changing the film thickness of the coating film, it showed excellent crack resistance of 1,450 nm. Moreover, when the dielectric constant of the coating film was evaluated, it showed a very low dielectric constant of 2.54.

Example 2
The coating film was evaluated in the same manner as in Example 1 except that the sample (A-1) added with 10% polymer (I-10) was used. The evaluation results are shown in Table 1.
Example 3
The coating film was evaluated in the same manner as in Example 1 except that 5 g of a sample (A-1) / sample (A-2) mass ratio 1/1 mixture was used. The amount of solvent was adjusted appropriately. The evaluation results are shown in Table 1.
Examples 4-6
Sample (A-1) / Diphenylacetylene, Sample (A-2) / Diphenylacetylene and Sample (A-1) / Polymer (I-10) / Diphenylacetylene in a mass ratio of about 8/1/1 g The coating film was evaluated in the same manner as in Example 1 except that it was used. The amount of solvent was adjusted appropriately. The evaluation results are shown in Table 1.
Comparative Example As a comparative example, an insulating film prepared in the same manner as in Example 1 of JP-A-11-40554 was evaluated in the same manner as the insulating film in Example 1. The evaluation results are shown in Table 1.
However, it was observed that the dielectric constant was 2.80 and increased to 3.20 after PCT.

Claims (3)

An insulating film forming material comprising a polymer (A) having a repeating unit represented by the following general formula (I):

In the general formula (I), R _{1 to} R ₇ may be the same or different and can each be a hydroxyl group, a monovalent hydrocarbon group, or a hydrocarbon group by Diels-Alder reaction and subsequent elimination reaction. A monovalent group, a group in which a carbon atom of a monovalent hydrocarbon group is partly replaced by a silicon atom, or a carbon atom of a monovalent group that can become a hydrocarbon group by a Diels-Alder reaction and subsequent elimination reaction Represents a group in which a part of is replaced by a silicon atom. One of X, Y, and Z represents a hydroxyl group, and the remaining two are different from each other, and are selected from the following general formula (IB) linked on the -O- and oxygen atom side. n represents 1-10.

R _{11 to} R ₁₄ may be the same or different and have the same definition as R _{1 to} R ₇ .
R _{15 to} R ₁₇ may be the same or different and each represents a single bond or a divalent hydrocarbon group, or a divalent group that can become a hydrocarbon group by a Diels-Alder reaction and a subsequent elimination reaction.
R ₁₈ represents a single bond or —O—. m represents 0-10. Wherein at least one insulating film formed according to claim 1, characterized in that at least one condition is satisfied from among the following (i) ~ (iii) one of R ₁ to R ₁₇ in (I) material.
(i) It has at least one carbon-carbon triple bond.
(ii) It has at least one carbon-carbon double bond conjugated with an aromatic group or carbon-nitrogen double bond conjugated with an aromatic group.
(iii) having at least one aromatic ring having 10 or more carbon atoms.   An insulating film obtained using the insulating film forming material according to claim 1.