JPH0685091A - Interlayer dielectric film - Google Patents

Abstract

PURPOSE:To provide an interlayer dielectric film which is easy to apply and cure, and which has small distortion when it is cured and has superior adhesiveness, smoothness and heat resistance with respect to a substrate. CONSTITUTION:In an interlayer dielectric film of a multilayer interconnection, a dielectric film is an interlayer dielectric film made of a heat resisting and thermosetting resin that has a viscosity of less than 10,000 poise before it is cured and a volumetric shrinkage rate of less than 5X10<-5>/ deg.C before and after it is cured. The dielectric film is an interlayer dielectric film made of a heat resisting and thermosetting resin that has a coefficient of thermal expansion of 5X10<-5>/ deg.C. As an example of the heat resisting and thermosetting resin, there is a thermosetting resin which contains aliphatic cyclic epoxy resin as a primary component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interlayer insulating film having excellent flatness and heat resistance which can be used in LSIs and multilayer wiring boards.

[0002]

2. Description of the Related Art Conventionally, an interlayer insulating film used for an LSI or the like has been obtained by laminating an inorganic material such as SiO ₂ by a sputtering method or the like, but it is difficult to form a multilayer with poor flatness. . Recently, an interlayer insulating film has been developed that uses polyimide to improve its flatness. However, the use of a solvent causes film loss, and the coating must be applied twice to improve the flatness. In addition, there is a problem such as poor adhesion to the substrate.

[0003]

DISCLOSURE OF THE INVENTION An object of the present invention is to easily apply and cure the composition, and to reduce the distortion during the curing, and to improve the adhesion to the substrate.
It is to provide an interlayer insulating film having excellent flatness and heat resistance.

[0004]

The present invention will be described in brief. The first invention of the present invention relates to an interlayer insulating film,
In an interlayer insulating film for multi-layer wiring, the insulating film has a viscosity of 10,000 poise or less before curing and a volume shrinkage ratio of 5% before and after curing.
It is characterized by comprising the following heat-resistant thermosetting resins. A second invention of the present invention relates to the interlayer insulating film of the first invention, wherein the insulating film has a coefficient of thermal expansion of 5 × 10 5.
It is characterized by being made of a heat resistant thermosetting resin of ^-5 / ° C or less.

As a result of intensive studies conducted by the present inventors in order to achieve the above object, the thermosetting resin containing an aliphatic cyclic epoxy resin as a main component has a low viscosity and a small curing shrinkage and thermal expansion coefficient. The inventors have found that they are excellent in heat resistance and are extremely excellent in flatness when applied to an interlayer insulating film, and have completed the present invention.

Aliphatic cyclic epoxy is used as the main component of the heat-resistant thermosetting resin in the present invention, but one having a high reactivity of the epoxy part is preferable. As such an example, 3,4-epoxycyclohexylmethyl-3,4
-Epoxycyclohexanecarboxylate, 3,4-
Epoxycyclohexylethyl-3,4-epoxycyclohexanecarboxylate, vinylcyclohexene dioxide, allylcyclohexene dioxide, 3,4-
Epoxy-4-methylcyclohexyl-2-propylene oxide, 2- (3,4-epoxycyclohexyl-
5,5-spiro-3,4-epoxy) cyclohexane-
m-dioxane, bis (3,4-epoxycyclohexyl) adipate, bis (3,4-epoxycyclohexylmethyl) adipate, bis (3,4-epoxycyclohexyl) ether, bis (3,4-epoxycyclohexylmethyl) ether, Examples thereof include bis (3,4-epoxycyclohexyl) diethylsiloxane. These aliphatic cyclic epoxy compounds may be used alone or as a mixture.

Compounds such as an epoxy resin diluent, a flexibility imparting agent, a characteristic modifier, and a curing agent can be added as a subcomponent of the heat resistant thermosetting resin in the present invention. Examples of such compounds include poly (oxyethylene),
Poly (oxypropylene), polypropylene oxide triol, polycaprolactone triol, polybutadiene diol, polybutadiene diglycidyl ether,
Poly-1,4- (2,3-epoxybutane) -co-1,
2- (3,4-epoxy) -co-1,4-butadienediol, maleic anhydride-modified polybutadiene, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol Diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, o-phthalic acid glycidyl ester, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, allyl glycidyl ether, 2-ethylhexyl Glycidyl ether, phenyl glycidyl ether, phenol penta (oxyethylene) glycidyl ether, p- ert-butylphenyl glycidyl ether, dibromophenyl glycidyl ether, lauryl alcohol pentadeca (oxyethylene) glycidyl ether, sorbitan polyglycidyl ether, pentaerythritol polyglycidyl ether, triglycidyl tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether. , Polytetramethylene glycol diglycidyl ether, adipic acid diglycidyl ester, hydroquinone diglycidyl ether, bisphenol S diglycidyl ether, terephthalic acid diglycidyl ester, glycidyl phthalimide,
Cetyl glycidyl ether, stearyl glycidyl ether, p-octylphenyl glycidyl ether, p-
Examples thereof include phenyl phenyl glycidyl ether, glycidyl benzoate, glycidyl acetate, glycidyl butyrate, spiroglycol diglycidyl ether, reduced maltose polyglycidyl ether, and the like. The properties of the resin can be modified by adding these compounds individually or in a mixture to the main component.

As the curing agent for the thermosetting resin in the present invention, any curing agent that reacts with an epoxy group by heating may be used, but an amine curing agent is not desirable because it has poor heat resistance after curing. Examples of good heat resistance after curing include phthalic anhydride, trimellitic anhydride,
Pyromellitic anhydride, benzophenone tetracarboxylic acid anhydride, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anhydrotrimellitate), Δ ⁴ -tetrahydrophthalic anhydride, 4-methyl-
Delta ⁴ - tetrahydrophthalic anhydride, 3-methyl - [delta ⁴ -
Tetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, 4- (4-methyl-3-pentenyl) tetrahydrophthalic anhydride, maleated fatty acid, dodecenyl succinic anhydride, vinyl ether-maleic anhydride copolymer, alkylstyrene Acid anhydride type curing agents such as maleic anhydride copolymer, methylcyclohexene tetracarboxylic acid anhydride, succinic anhydride, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride and 3-methylhexahydrophthalic anhydride, , 2-methylimidazole, 2
-Ethyl-4-methyl imidazole, 2-undecyl imidazole, 2-heptadecyl imidazole, 2-phenyl imidazole, 1-benzyl-2-methyl imidazole, 1-cyanoethyl-2-methyl imidazole, 1
-Cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole,
1-Cyanoethyl-2-undecylimidazolium trimellitate, 1-Cyanoethyl-2-phenylimidazolium trimellitate, 2-Methylimidazolium isocyanurate, 2-Phenylimidazolium isocyanurate, 2,4-Diamino-6 -[2-Methylimidazolyl- (1)]-ethyl-s-triazine, 2,4-diamino-6- [2-ethyl-4-methylimidazolyl-
(1)] - imidazole curing agent such as ethyl -s- triazine, BF _{3-n-hexylamine,} BF ₃ - monoethylamine, BF ₃ - benzylamine, BF ₃ - diethylamine, BF ₃ - piperidine, BF ₃ - triethylamine, BF ₃ - aniline, BF _{4-n-hexylamine,} BF ₄ - monoethylamine, BF ₄ - benzylamine, BF ₄ - diethylamine, BF ₄ - piperidine, B
F ₄ - triethylamine, BF ₄ - aniline, PF ₅ -
Ethylamine, PF ₅ - isopropylamine, PF ₅ -
Butylamine, PF ₅ - laurylamine, PF ₅ - benzylamine, AsF ₅ - Lewis acids such as laurylamine -
Examples thereof include amine complex-based curing agents, dicyandiamide and its derivatives, organic acid hydrazides, diaminomaleonitrile and its derivatives, and amineimide curing agents. These curing agents may be used alone or as a mixture thereof. Then, a tertiary amine, boric acid ester, Lewis acid, organic metal compound, organic acid metal salt, imidazole or the like may be used as a curing accelerator.

Further, a silane coupling agent may be added to the thermosetting resin of the present invention to improve the adhesiveness. Examples of the silane coupling agent include γ-aminopropyltriethoxysilane and N-β- (aminoethyl).
-Γ-aminopropyltrimethoxysilane, N-β-
(Aminoethyl) -γ-aminopropyltriethoxysilane, N-bis [β- (aminoethyl)]-γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ -Methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl)-
γ-aminopropyltrimethoxysilane hydrochloride, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxy Silane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltriethoxysilane, benzyl Trimethylsilane, vinyltris (2-methoxyethoxy) silane, γ-methacryloxypropyltris (2-methoxyethoxy) silane, β- (3,4-epo) Shi cyclohexyl) ethyltrimethoxysilane, .gamma.-ureidopropyltriethoxysilane, .gamma. isocyanuric triethoxysilane, etc. n- octyl triethoxy silane.

The above-mentioned heat-resistant thermosetting resin containing the main component, the subcomponent, the curing agent, the curing accelerator, the silane coupling agent and the like made of the aliphatic cyclic epoxy, which is liquid at room temperature, is spin-coated. It can be applied to a substrate or a wiring board by the method. If the viscosity of the resin is too high, it becomes difficult to apply the resin evenly. Therefore, the viscosity is preferably 10,000 poise or less. When the cured interlayer insulating film is thick, it is desirable that the viscosity of the resin is high, and when it is thin, it is desirable that the viscosity is low. Further, in the case of applying by spin coating, the interlayer insulating film after curing can be prepared by applying at low speed when making a thick film and by applying at high speed when making a thin film. The applied heat-resistant thermosetting resin is heat-cured and can be used as an interlayer insulating film.

Generally, curing shrinkage occurs when the thermosetting resin is cured. When a heat-resistant thermosetting resin is used as the interlayer insulating film, when the curing shrinkage is large, distortion occurs between the substrate and the wiring part, so the wiring part is cut during the curing, peeled off from the substrate, May be cracked. A material having a large curing shrinkage may impair the reliability when used as a component. Further, when the interlayer insulating film is formed of a resin having a large curing shrinkage, the flatness of the film becomes poor. Therefore, it is desirable that the curing shrinkage rate be 5% or less. In the case of a heat-resistant thermosetting resin whose main component is an aliphatic cyclic epoxy resin, the cure shrinkage can be reduced to 5% or less.

When a resin is used for the interlayer insulating film, the coefficient of thermal expansion of the resin is generally higher than that of the substrate or wiring material. In many cases, the heat cycle causes distortion, and swelling or fraying occurs between the interlayer insulating film and the substrate or wiring portion. Therefore, it is desirable to make the coefficient of thermal expansion of the resin as small as possible. In the case of a heat-resistant thermosetting resin whose main component is an aliphatic cyclic epoxy resin, the coefficient of thermal expansion can be reduced to 5 × 10 ⁻⁵ / ° C. or less.

When a resin is used for an interlayer insulating film such as a wiring board, it is naturally necessary to have solder heat resistance. Further, in the multilayer wiring, when the wiring is formed on the interlayer insulating film by a sputtering method or the like to form a fine wiring pattern, the temperature rise on the surface of the interlayer insulating film is unavoidable. Heat resistance is needed. A heat-resistant thermosetting resin whose main component is an aliphatic cyclic epoxy resin has higher heat resistance than general epoxy resins.

The above points will be specifically described with reference to the accompanying drawings. FIG. 1 is a diagram showing an example of an interlayer insulating film and a manufacturing process of the present invention, and FIG. 2 is a diagram showing an example of a conventional polyimide interlayer insulating film and a manufacturing process. As shown in FIG. 2, distortion occurs in the conventional type including a solvent, but in the case of the present invention, such a problem was solved as shown in FIG.

[0015]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition,
Parts in the examples are parts by weight.

Example 1 Aliphatic cyclic epoxy 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (manufactured by Union Carbide, trade name ERL-4)
221) 100 parts of methyl nadic acid anhydride (NMA) as a curing agent in 100 parts, and 2-ethyl-4 as a curing accelerator.
-Methylimidazole (2E4MZ) and 2 parts of γ-glycidoxypropyltrimethoxysilane (manufactured by Nippon Unicar, trade name A-187) as a silane coupling agent were blended to obtain a heat resistant thermosetting resin. When the viscosity of this resin was examined, it was 5 poise. The curing conditions were heating at 120 ° C. for 2 hours, heating at 150 ° C. for 3 hours, and further heating at 200 ° C. for 1 hour. The cure shrinkage was determined by measuring the density before and after curing, and was 4.3%. The coefficient of thermal expansion was 4.8 × 10 ⁻⁵ / ° C. as a result of using a thermomechanical coefficient of thermal expansion measuring device (TM7000 manufactured by Vacuum Riko). A heat-resistant thermosetting resin was applied on a silicon substrate by spin coating, and the cured product was cut into strips together with the substrate and immersed in a solder bath at 280 ° C. for 30 seconds, resulting in no peeling or swelling. The solder heat resistance was good. A heat-resistant thermosetting resin is applied by spin coating to a thickness of 3 μm on aluminum wiring, which is a wiring pattern with a height of 2 μm and a width of 1, 2, 5, 10 μm formed on the silicon substrate at the same line pace as the wiring pattern width Cross-section of the cured product is a scanning electron microscope (S800 manufactured by Hitachi, Ltd.)
As a result, the upper part of the wiring part and the upper part of the inter-wiring part were flat, and no dent in the upper part of the wiring part or swelling of the upper part of the wiring part was observed. The evaluation results are shown in Table 3 together with other examples.

Examples 2 to 18 In place of ERL4221, the main component in Example 1 was 2-
(3,4-epoxycyclohexyl-5,5-spiro-
3,4-Epoxy) cyclohexane-m-dioxane (Union Carbide Co., trade name ERL-423
4), or bis (3,4-epoxycyclohexyl) adipate (manufactured by Union Carbide Co., trade name ERL-4)
299), vinyl cyclohexene dioxide (manufactured by Union Carbide Co., trade name ERL-4206), and an aliphatic cyclic epoxy, and polybutadiene diglycidyl ether (manufactured by Nagase Chemical Industry Co., Ltd., trade name Denalex R-45 EPT) and polypropylene Xidotriol (Union Carbide, trade name NIAX Polyol
LHT-240), glycidyl phthalimide (manufactured by Nagase Kasei Co., Ltd., trade name Denacol EX-731), BF instead of NMA or 2E4MZ as a curing agent and curing accelerator.
₃ -monoethylamine (BF ₃ -MEA) and 1-benzyl-2-methylimidazole (1B2MZ) were used, and γ-mercaptopropyltrimethoxysilane (manufactured by Nippon Unicar Co., Ltd., a product instead of A-187 as a silane coupling agent) A heat-resistant thermosetting resin was obtained with the compounding composition shown in Table 1 and Table 2 using the name A-189). The curing conditions were the same as in Example 1. The same evaluation as in Example 1 was performed for these.
However, if the viscosity is higher than 100 poise,
The flatness was evaluated by the following method. A heat-resistant thermosetting resin is applied to a thickness of 15 μm by spin coating on aluminum wiring formed with a wiring pattern of height 10 μm width 10, 20, 50, 100 μm on a silicon substrate at the same line pace as the wiring pattern width, and by heating. The cross section of the cured product was observed with a scanning electron microscope (S800 manufactured by Hitachi, Ltd.). The evaluation results are shown in Table 3.

Comparative Examples 1 to 3 Bisphenol A diglycidyl ether (trade name Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) was used in place of the main component ERL-4221 of Example 1, and the compositions shown in Tables 1 and 2 below. To obtain a thermosetting resin. Using this thermosetting resin, the same evaluations as in Examples 1 to 18 were performed.
The evaluation results are shown in Table 3. Regarding the solder heat resistance, in all the samples of Comparative Examples 1 to 3, the film peeled from the substrate.

Comparative Example 4 In Examples 1 to 18 and Comparative Examples 1 to 3, an epoxy resin was used, but in Comparative Example 4, a proven polyimide resin was used as an interlayer insulating film. A polyimide coating agent (Hitachi Kasei, trade name PIQ-1500) was spin-coated on a silicon wafer and heated at 100 ° C. for 1 hour, 200 ° C. for 1 hour, and 350 ° C. for 30 minutes to obtain a film. The coating agent had a resin concentration of 14.5% and a viscosity of 11 poise. The characteristic evaluation was performed in the same manner as in Example 1. The results are shown in Table 3. Although the heat resistance of the solder was good, the flatness was poor, and a step was generated between the upper part of the wiring and the upper part between the wirings, swelling (convex part) at the upper part of the wiring, and denting (concave part) between the wirings. The difference in unevenness was 1.2 μm at a large area and 0.6 μm at a small area.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

As described above, the interlayer insulating film of the present invention is easy to apply, has a small shrinkage at the time of curing, and uses the heat-resistant thermosetting resin excellent in the adhesiveness to the substrate. It has the advantage of excellent heat resistance.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an interlayer insulating film and a manufacturing process of the present invention.

FIG. 2 is a diagram showing an example of a conventional polyimide interlayer insulating film and a manufacturing process.

Claims (3)

[Claims] 1. An interlayer insulating film for multi-layer wiring, wherein the insulating film is made of a heat-resistant thermosetting resin having a viscosity of 10,000 poise or less before curing and a volume shrinkage ratio of 5% or less before and after curing. Interlayer insulation film. 2. The interlayer insulating film according to claim 1, wherein the insulating film is made of a heat resistant thermosetting resin having a coefficient of thermal expansion of 5 × 10 ⁻⁵ / ° C. or less. 3. The interlayer insulating film according to claim 1, wherein the heat-resistant thermosetting resin is a thermosetting resin whose main component is an aliphatic cyclic epoxy resin.