JPH1036772A - Coating liquid for forming silica coating film, silica coating film and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating liquid for forming a silica coating film, useful for obtaining the silica coating film good in coating film formability and low in dielectric constant, to obtain the silica coating film not generating cracks even in large coating film thickness and low in the dielectric constant by using this coating liquid for forming the silica coating film, and to provide a semiconductor device using the silica coating film. SOLUTION: This coating liquid forming a silica coating film contains (A) a siloxane oligomer obtained by hydrolyzing and polycondensing a methyltrialkoxysilane of the formula: CH3 -Si-(OR)3 (R is a 1-4C alkyl) and a hydrogenated trialkoxysilane of the formula: H-Si-(OR')3 (R' is a 1-4c alkyl) and (B) a metal catalyst containing a metal belonging to the group VIII in the periodic table. The semiconductor device having a silica coating film as an interlayer insulating film is formed by coating the coating liquid on the surface of a substrate, drying the coated coating liquid at 50-200 deg.C, and subsequently curing the dried coating film at 300-500 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating solution for forming a silica-based film, a silica-based film and a semiconductor device obtained by using the same, and more particularly to a coating solution having no cracks even when fired at 500.degree. The present invention relates to a coating solution for forming a silica-based film capable of forming a film, a silica-based film obtained by using the same, and a semiconductor device.

[0002]

2. Description of the Related Art Hitherto, as a method of insulating a semiconductor element such as an IC or an LSI, the hydrolysis of a silanol compound has been used. A method of firing a condensate to form a silica-based coating is often used. The method using tetrafunctional silane such as tetraethoxysilane is most known, but the method using only tetrafunctional silane has a large shrinkage stress generated when firing to form a silicic coating, When the film thickness is large, there is a problem that cracks occur and the dielectric film is high due to high hygroscopicity of the film. On the other hand, a method for forming a silica-based film using hydropolysilazane (Japanese Patent Laid-Open No. 4-3417)
No. 05, Japanese Patent Application Laid-Open No. 5-105486) has been proposed. However, in this method, when the firing temperature is set to a relatively low value of about 500 ° C., the silica film obtained has a large water absorption, and the silica film has a large water absorption. There is a problem that the dielectric film is higher than the formed silica film.

[0003]

SUMMARY OF THE INVENTION Claim 1 or Claim 2
The present invention provides a coating liquid for forming a silica-based film for obtaining a silica-based film having good film-forming properties and a low dielectric constant. The invention according to claim 3 provides a silica-based coating which is obtained by using such a coating liquid for forming a silica-based coating and has a low dielectric constant without cracks even in a thick film. The invention according to claim 4 provides a semiconductor device using such a silica-based coating.

[0004]

The present invention relates to (A)
[General formula (I)]

Embedded image (Wherein, R represents an alkyl group having 1 to 4 carbon atoms) and a methyltrialkoxysilane represented by the general formula (II):

Embedded image (Wherein, R ′ represents an alkyl group having 1 to 4 carbon atoms).
The present invention relates to a cloth solution for forming a silica-based film, comprising a siloxane oligomer obtained by condensation polymerization and (B) a metal catalyst containing a metal belonging to Group VIII of the periodic table.

[0005] The present invention also relates to a coating solution for forming a silica-based film, wherein the metal catalyst containing a Group VIII element of the periodic table comprises a rhodium or ruthenium compound. Also, the present invention provides a coating solution for forming a Rica-based film on a substrate surface, and then applying the coating solution at 50 to 200 ° C.
And then calcined at 300 to 500 ° C. Further, the present invention relates to a semiconductor device using the silica-based coating as an interlayer insulating film.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the methyltrialkoxysilane represented by the general formula (I) used in the present invention include those shown in Chemical Formula 5.

Embedded image

Examples of the hydrogen trialkoxysilane represented by the general formula (II) used in the present invention include those shown in Chemical formula 6.

Embedded image

The mixing ratio of these two alkoxysilane compounds is preferably in the range of 0.2 to 1 mole of hydrogen trialkoxysilane per mole of methyl trialkoxysilane.

The hydrolysis and polycondensation reaction of these two alkoxysilane compounds is preferably carried out in the presence of water and a catalyst in a solvent, and the catalyst used at this time is an acid catalyst, Any basic catalyst can be used. Examples of the acid catalyst include phosphoric acid, nitric acid, sulfuric acid, maleic acid, fumaric acid, formic acid, and acetic acid, and examples of the basic catalyst include ammonia. The use amount of these catalysts is preferably in the range of 0.1 to 0.001 mol based on 1 mol of the total amount of the alkoxysilane compound.

In the above reaction, water is preferably present in the range of 0.1 to 10 mol, particularly preferably 0.5 to 1.5 mol, per 1 mol of the total amount of the alkoxysilane compound. The water used for the hydrolysis is preferably added gradually using a dropping funnel or the like. When added all at once, the heat of hydrolysis causes the liquid temperature to rise sharply,
Polycondensation tends to proceed with polycondensation, and the stability of the coating solution for forming a silica-based film tends to decrease. It is preferable to adjust the dropping speed so that the liquid temperature is 50 ° C. or lower.

Further, the solvent used in the above reaction includes methanol, ethanol, butanol, propanol, isopropanol, isobutanol, 2-butanol, tetrabutanol, pentyl alcohol, 2-pentyl alcohol, 3-pentyl alcohol, isopentyl Alcohols such as alcohol, methyl acetate, ethyl acetate, isopropyl acetate, propyl acetate, butyl acetate,
Esters such as isobutyl acetate and sec-butyl acetate; glycols such as ethylene glycol diethyl ether, ethylene glycol monohexyl ether, dipropylene glycol monopropyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether and propylene glycol monophenyl ether Examples thereof include aromatic solvents such as ethers, benzene, toluene, and xylene. Even if these solvents are used alone,
Further, two or more kinds may be used in combination.

The metal catalyst containing a Group VIII metal of the Periodic Table used in the present invention includes a metal complex of a Group VIII metal such as Ru, Rh, Pd, and Pt, a metal oxide, a metal carboxylate, Examples thereof include metal inorganic salts and carbon supports. Specific examples include ruthenium acetylacetonate, rhodium acetylacetone, platinum acetylacetonate, palladium acetylacetonate, ruthenium dodecacarbonyl, ruthenium oxide, ruthenium oxide hydrate, rhodium oxide hydrate, palladium oxide, platinum oxide, ruthenium acetate , Rhodium acetate, palladium acetate, ruthenium nitrate, rhodium nitrate, platinum carbon and the like. The amount used is preferably in the range of 0.01 to 1 part by weight based on 100 parts by weight of the siloxane oligomer obtained by the above-mentioned hydrolysis / condensation polymerization.

The coating solution for forming a silica-based film in the present invention can be produced by adding the above-mentioned noble metal-based catalyst to the reaction product solution for preparing the siloxane oligomer. In order to form an oxide film using the coating solution thus obtained, the coating solution is immersed on a substrate such as glass, ceramics, a silicon wafer, or a silicon wafer on which a circuit is formed, by spinning, and rotating. After coating by a method such as a coating method, the coating is dried at 50 to 200 ° C, preferably 100 to 150 ° C, and then fired at 300 to 500 ° C. A semiconductor element can be obtained using this silica-based coating as a wiring interlayer film (insulating interlayer film).

[0014]

The present invention will be described below in more detail with reference to examples.

Example 1 Methyltrimethoxysilane [CH ₃ Si (OCH ₃ ) ₃ ] 6
7 g and hydrogen trimethoxysilane [HSi (OCH ₃ ) ₃ ] 5
3 g was dissolved in 400 g of isopropyl alcohol, and a mixed solution of 63 g of water and 1.0 g of nitric acid was added dropwise over 1 hour, and the mixture was further reacted at room temperature for 24 hours. After completion of the reaction, 0.2 g of ruthenium acetate was mixed and stirred for 1 hour to prepare a coating liquid for forming a silica film. This reaction product solution was applied on a silicon wafer at 2,000 rpm using a spinner, dried on a hot plate controlled at 150 ° C. for 1 minute, and then placed in an electric furnace at 450 ° C. in the atmosphere.
For 1 hour, a colorless, transparent and crack-free film was obtained. The thickness of this film was measured to be 0.4
μm. 1 μm of aluminum coating on this coating
And the dielectric constant of this sample is set to LF.
Frequency 10 to 1000 using an impedance maker
It was 3.2 when measured by changing to 0 Hz.

Example 2 Methyltrimethoxysilane [CH ₃ Si (OCH ₃ ) ₃ ] 1
00g hydrogen trimethoxysilane [HSi (OCH _{3) 3]}
53 g was dissolved in 400 g of isopropyl alcohol, and 63 g of water and 1 ml of nitric acid were added thereto. After dropping 0 g of the mixture for 1 hour, the mixture was further reacted at room temperature for 24 hours. After the reaction,
0.2 g of rhodium acetate was mixed and stirred for 1 hour to prepare a coating liquid for forming a silica film. Using this reaction solution, a film was formed in the same manner as in Example 1. This film was colorless and transparent, had no cracks, and its film thickness was measured to be 0.4 μm. An aluminum film was formed on this film in the same manner as in Example 1, and the dielectric constant was measured to be 2.8.

Comparative Example 1 Methyltrimethoxysilane [CH ₃ Si (OCH ₃ ) ₃ ] 6
7 g and hydrogen trimethoxysilane [HSi (OCH ₃ ) ₃ ] 5
3 g was dissolved in 400 g of isopropyl alcohol, and a mixed solution of 63 g of water and 1.0 g of nitric acid was added dropwise over 1 hour, and the mixture was further reacted at room temperature for 24 hours to prepare a coating solution for forming a silica film. Using this reaction solution, a film was formed in the same manner as in Example 1. This film was colorless and transparent, had no cracks, and its film thickness was measured to be 0.4 μm. An aluminum film was formed on this film in the same manner as in Example 1, and the dielectric constant was measured.
Met.

[0018]

According to the first or second aspect of the present invention, the coating solution for forming a silica-based film can form a film having a sintering temperature of 500 ° C. or less, is excellent in film-forming properties, and has a low hygroscopic property, and therefore has a dielectric constant. Low coating film can be formed. The silica coating according to the third aspect is free from cracks and has a low hygroscopicity, and thus has a low dielectric constant. According to a fourth aspect of the present invention, there is provided a semiconductor device having the above-described silica coating having excellent properties as an interlayer insulating film.

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Shigeru Nobe 4-3-1-1, Higashicho, Hitachi City, Ibaraki Pref. Hitachi Chemical Co., Ltd. Yamazaki Plant

Claims (4)

[Claims] (1) (A) Chemical formula 1 [General formula (I)] (Wherein, R represents an alkyl group having 1 to 4 carbon atoms) and a methyltrialkoxysilane represented by the general formula (II): (Wherein, R ′ represents an alkyl group having 1 to 4 carbon atoms).
A cloth fluid for forming a silica-based film, comprising a siloxane oligomer obtained by condensation polymerization and (B) a metal catalyst containing a metal of Group VIII of the periodic table. 2. The silica-based coating liquid according to claim 1, wherein the metal catalyst containing a Group VIII element of the periodic table comprises a rhodium or ruthenium compound. 3. The coating liquid according to claim 1 or 2,
A silica-based coating formed by coating on a substrate surface, drying at 50 to 200 ° C, and then firing at 300 to 500 ° C. 4. A semiconductor device comprising the silica-based coating according to claim 3 as an interlayer insulating film.