JPH11236530A - Coating solution for forming silica film, and silica film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating soln. for silica film formation which exhibits improved adhesion to metal wiring, is thermally stable, and has good film- forming properties and a silica film formed from the same. SOLUTION: This coating soln. contains (A) an alkoxysilane compd. of the formula: Rn Si(OR)4-n (R is 1-4C alkyl; and n is 0-2), (B) an alkoxysilane oligomer obtd. by the hydrolysis and polycondensation of a phenylalkoxysilane compd. of the formula: PhSi(OR)3 (Ph is phenyl; and R is alkyl), and (C) at least one compd. selected from among alkoxysilane compds. of the formula: Hn Si(OR)4-n (R is 1-4C alkyl; and n is 1 or 2), aminoalkylalkoxysilane compds., and zirconium alkoxide compds. The soln. is applied to a substrate surface, dried at 50-350 deg.C, and baked at 350-600 deg.C to form a silica film.

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 coating and a silica-based coating, and more particularly, to a silica-based coating which is thermally stable and has good film-forming properties and a coating for forming the silica-based coating. Liquid.

[0002]

2. Description of the Related Art Conventionally, as a method of flattening an interlayer insulating film of a semiconductor element such as an IC or an LSI, SiO ₂ , SiN is formed on a substrate having a patterned wiring layer by a vapor deposition method such as vacuum deposition and CVD. The first layer of an interlayer insulating film is formed, and the second layer is spin-coated with an SOG solution (oligomer of organosiloxane), followed by heat treatment to form an organosiloxane-based film. Next, an SOG planarization process using a three-layer interlayer film in which a third interlayer insulating film is formed in the same manner as the first layer is widely used.

In recent years, as the speed of ICs, LSIs, and the like has been increased, there is a limit in reducing the dielectric constant of an interlayer insulating film having a three-layer structure. Proposed. However, since a single layer of the SOG film has extremely poor adhesion to metal wiring as compared with an oxide film formed by CVD or the like, there is a problem that the wiring is disconnected in a subsequent semiconductor manufacturing process.

[0004]

According to the first or second aspect of the present invention, there is provided a coating liquid for forming a silica-based film, which has improved adhesion to metal wiring, is thermally stable and has good film-forming properties. Is what you do. The third aspect of the present invention is to provide a silica-based coating film having excellent adhesion to metal wiring and easy to form a film.

[0005]

According to the present invention, there is provided (A) a compound represented by the following general formula (I):

Embedded image (Wherein R represents an alkyl group having 1 to 4 carbon atoms, and n represents a positive number of 0 to 2), and (B) a general formula (II)

Embedded image (Wherein Ph represents a phenyl group, R represents an alkyl group having 1 to 4 carbon atoms), and an alkoxysilane oligomer obtained by hydrolysis and polycondensation of a phenylalkoxysilane compound represented by the formula (C): ) General formula (III)

Embedded image Wherein R is an alkyl group having 1 to 4 carbon atoms, and n is 1 or 2
Which means at least one compound selected from the group consisting of an alkoxysilane compound, an aminoalkylalkoxysilane compound and a zirconium alkoxide compound.

The present invention also relates to a coating solution for forming a silica-based film, wherein at least one compound selected from the group consisting of an alkoxysilane compound, an aminoalkylalkoxysilane compound and a zirconium alkoxide compound is added to the alkoxysilane oligomer by one to one. The present invention relates to a coating solution for forming a silica-based film containing 10% by weight. In addition, the present invention provides that any one of these coating liquids is applied on a substrate surface, dried at 50 to 350 ° C., and then dried at 350 to 60 ° C.
The present invention relates to a silica-based coating fired at 0 ° C.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The alkoxysilane represented by the general formula (I) is specifically

Embedded image Such as tetraalkoxysilane,

Embedded image Monoalkyl trialkoxysilane such as,

Embedded image And the like, and one or more of these may be used.

The phenyl trialkoxysilane compound represented by the general formula (II) is specifically,

Embedded image And the like.

The alkoxysilane compound represented by the general formula (III) is specifically,

Embedded image And the like.

The aminoalkylalkoxysilane compound according to the present invention is a silano compound having an aminoalkyl group and an alkoxy group in the molecule. The aminoalkyl group preferably has 1 to 4 carbon atoms. Are preferably 1 to 4. Examples of such an aminoalkylalkoxysilane compound include:

Embedded image And the like.

The zirconium complex compounds used in the present invention include zirconium acetate, zirconium acetylacetone, zirconium alkoxide compounds, and the like, and zirconium alkoxide compounds include zirconium tetra n-propoxide, zirconium tetra
Zirconium tetraalkoxide compounds (alkoxy group having 1 to 4 carbon atoms) such as iso-propoxide, zirconium tetra n-butoxide, zirconium tetra iso-butoxide, and acetylacetone zirconium n-butoxide.

The proportions of the tetraalkoxysilane, monoalkyltrialkoxysilane, dialkyldialkoxysilane and phenyltrialkoxysilane used in the production of the alkoxysilane oligomer used in the present invention are not limited, but are compounded as follows. Preferably. That is, in order to form a high-quality silica-based coating, (a) 90 to 50 mol% of tetraalkoxysilane or monoalkyl trialkoxysilane, and (b) dialkyldialkoxysilane, based on the total amount of the alkoxysilane compound used. ４０40 mol% and (c) 10-50 mol% of phenyl trialkoxysilane
It is preferable that the amount is 0 mol%.

In the present invention, an organic solvent is preferably used as a solvent in the coating solution for forming a silica-based film.
Examples of the organic solvent include alcohols such as methanol, ethanol, propanol and butanol, methyl acetate, ethyl acetate, propyl acetate, acetate esters such as butyl acetate, ethylene glycol monomethyl acetate, glycol acetate solvents such as ethylene glycol diacetate,
Amide solvents such as N, N-dimethyl-2-pyrrolidone,
Various solvents such as a glycol ether-based solvent are mentioned, and one or more of these are used.

The alkoxysilane oligomer in the present invention is produced by hydrolyzing and polycondensing an alkoxysilane compound represented by the general formula (I) and a phenylalkoxysilane compound represented by the general formula (II). At this time, it is preferable to use inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid and hydrofluoric acid as catalysts, and organic acids such as oxalic acid, maleic acid, sulfonic acid and formic acid, and basic acids such as ammonia and trimethylammonium. A catalyst can also be used. These catalysts are used in an appropriate amount according to the amount of the alkoxysilane compound represented by the general formula (I), and preferably, the catalyst is represented by the alkoxysilane compound represented by the general formula (I) and the alkoxysilane compound represented by the general formula (II). The phenylalkoxysilane compound is used in the range of 0.001 to 0.5 mol per 1 mol of the total amount.

The above-mentioned hydrolysis / polycondensation is preferably carried out in the above-mentioned solvent. Also, water is allowed to be present during this reaction. The amount of water is also determined as appropriate. However, if the amount is too small or too large, there is a problem that the storage stability of the coating solution is lowered. Therefore, the amount of water is determined by the alkoxy represented by the general formula (I). The amount is preferably in the range of 0.5 to 4 mol per 1 mol of the total amount of the silane compound and the phenylalkoxysilane compound represented by the general formula (II). The reaction solution (silanol oligomer solution) of the hydrolysis / polycondensation product obtained as described above can be used as it is. After the solvent is removed, it is again dissolved in the solvent and used as a silanonyl oligomer solution. The reaction temperature is preferably in the range of 0 to 50 ° C.

The addition amount of at least one of the alkoxysilane compound, aminoalkylalkoxysilane compound and zirconium alkoxide compound represented by the general formula (III) used in the present invention depends on the adhesion and film quality of the silica-based coating. From 1 to the alkoxysilane oligomer (the resin component of the hydrolysis / polycondensation product obtained above).
It is preferred to be in the range of 10% by weight.

The coating liquid for forming a silica-based film of the present invention comprises an alkoxysilane oligomer, an alkoxysilane compound,
Alternatively, it is obtained by mixing an aminoalkylalkoxysilane compound or a zirconium alkoxide compound.

In order to form a silica-based film using the coating solution thus obtained, a silicon wafer, a metal plate such as aluminum, a silicon wafer having a metal formed on the surface, and a circuit are formed. After coating on a substrate such as a silicon wafer by a method such as immersion or spin coating, drying is performed at 50 to 350 ° C., preferably 100 to 250 ° C., and then 350 to 600 ° C. in a nitrogen atmosphere. Preferably, firing is performed at 350 to 450 ° C. A semiconductor device can be obtained by using this silica-based coating as an interlayer film (insulating interlayer film) having a multilayer wiring structure.

The silica-based coating obtained by using the coating solution of the present invention has improved adhesiveness to metal as compared with a silica-based coating obtained by using conventional hydrolysis-condensation polymerization of alkoxysilane. As a result, a silica film having the same thermal stability and film formability as a silica-based film obtained by the conventional hydrolysis-condensation polymerization of alkoxysilane is formed. A semiconductor element can be obtained by using this silica-based coating as a wiring interlayer film (interlayer insulating film).

An example of the manufacturing process of the semiconductor device of the present invention will be described below. FIG. 1 is a manufacturing process diagram of a semiconductor device having a multilayer wiring structure. In FIG. 1, a semiconductor substrate 1 such as a silicon wafer, a glass plate, or a metal plate having circuit elements is provided.
Is covered with a protective film 2 such as a silicon oxide film except for a predetermined portion of the circuit element, and the first conductor layer 3 is formed on the exposed circuit element.
Are formed. The above-mentioned silica-based coating solution is applied on the semiconductor substrate by a spinner method or the like, and the interlayer insulating film 4 made of a polysiloxane film is formed by removing the solvent by heat treatment and baking (step (a)).

Next, a photosensitive resin layer 5 of a chlorinated rubber type or a phenol novolak type is formed on the interlayer insulating film 4 by a spinner method, and a predetermined portion of the interlayer insulating film 4 is exposed by a known photolithography technique. Thus, the window 6A is provided (step (b)).

The interlayer insulating film 4 of the window 6A is selectively etched by dry etching means using a fluorine-based gas such as carbon tetrafluoride (for example, a method using a fluorine-based gas such as carbon tetrafluoride). 6B is opened. Next, the photosensitive resin layer 5 is completely removed by using an etching solution that does not corrode the first conductor layer 3 exposed from the window 6B but corrodes only the photosensitive resin layer 5 (step (c)).

Further, the second conductor layer 7 is formed by using a known metal film forming method and a photolithography technique, and the electrical connection with the first conductor layer 3 is completely performed (step (d)).

When a multilayer wiring structure having three or more layers is formed, the above steps are repeated to form each layer. That is, a step (a) of forming an interlayer insulating film to be an insulating layer on the conductor layer, a predetermined portion of the coating is selectively removed, a window is opened, and the film is connected to a predetermined portion of the lower conductor layer. Step (d) of forming the upper conductor is repeated.
On the surface of the multilayer wiring structure manufactured in this way,
Usually, a surface protective layer made of an organic material such as a polyimide resin or an inorganic material such as silicon nitride is formed. A window similar to the windows 6A and 6B may be opened in a predetermined portion of the surface protective layer in some cases. The entire semiconductor device is usually sealed with a sealing material containing an epoxy resin or the like.

[0025]

The present invention will be described below in more detail with reference to examples. Example 1 51.0 g of tetramethoxysilane, 23.0 g of methyltrimethoxysilane, 40.0 g of dimethyldimethoxysilane
g and 33.0 g of phenyltrimethoxysilane were dissolved in 400.0 g of isopropyl alcohol, and a solution obtained by dissolving 210 g of phosphoric acid in 50.0 g of water was added to this solution under stirring.
It was dropped over time. After stirring for 5 hours after the completion of dropping, 6.0 g of trimethoxysilane was added, and the mixture was further stirred for 1 hour.

Further, this reaction product solution was applied to a substrate on which aluminum was formed 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 dried at 400 ° C. in a nitrogen atmosphere. When calcined in an electric furnace for 1 hour, a colorless, transparent and crack-free film was obtained. When the film thickness of the coating was measured, it was 0.3
μm.

Further, when the silica-based coating film was subjected to an adhesion test according to the grid test method J1SK5400, no peeling of the coating film was observed. Thereafter, the substrate was treated in a high-pressure steam sterilizer at 120 ° C. and 2.2 kgf / cm ² for 24 hours, and then subjected to a test for adhesion by a grid test, but no peeling of the coating was observed. Was.

Example 2 120.0 g of tetramethoxysilane and 40.0 g of phenyltrimethoxysilane were added to isopropyl alcohol 80
A solution of 0.5 g of maleic acid in 55.0 g of water was added dropwise to this solution over 1 hour with stirring. After stirring for 5 hours after the completion of the dropwise addition, 6.0 g of 3-aminopropyltriethoxysilane was added, and the mixture was further stirred for 1 hour.

The reaction solution was applied to a substrate having aluminum formed on a silicon wafer at 2,000 rpm using a spinner, dried on a hot plate controlled at 150 ° C. for 1 minute, and dried at 400 ° C. in a nitrogen atmosphere. When calcined in an electric furnace for 1 hour, a colorless, transparent and crack-free film was obtained. When the film thickness of the coating was measured, it was 0.3
μm.

Further, when the silica-based coating film was subjected to an adhesion test according to the grid test method J1SK5400, no peeling of the coating film was observed. afterwards. After the substrate was treated in a high-pressure steam sterilizer at 120 ° C. and 2.2 kgf / cm ² for 24 hours, an adhesion test was performed by a grid test, but no peeling of the coating was observed.

Example 3 87.0 g of tetramethoxysilane, 40.0 g of methyltrimethoxysilane and phenyltrimethoxysilane 2
7.0 g was dissolved in 280.0 g of isobrovir alcohol, and a solution in which 0.5 g of maleic acid was dissolved in 50.0 g of water was added dropwise to this solution over 1 hour with stirring. After stirring for 5 hours after the completion of dropping, 6.0 g of acetylacetone zirconium butoxide was added, and the mixture was further stirred for 1 hour.

This reaction solution was applied to a substrate on which aluminum was formed on a silicon wafer at 2,000 rpm using a spinner, dried on a hot plate controlled at 150 ° C. for 1 minute, and dried at 400 ° C. in a nitrogen atmosphere. When calcined in an electric furnace for 1 hour, a colorless, transparent and crack-free film was obtained. When the film thickness of the film was measured, it was 0.2
μm.

Further, when this silica-based coating film was subjected to an adhesion test in accordance with a cross-cut test method J1SK 5400, no peeling of the coating film was observed. Thereafter, the substrate was treated in a high-pressure steam sterilizer at 120 ° C. under a condition of 2.2 kgf / cm ² for 24 hours, and an adhesion test was performed by a grid test, but no peeling of the film was observed. .

Comparative Example 1 51.0 g of tetramethoxysilane, 23.0 g of methyltrimethoxysilane, 40.0 g of dimethyldimethoxysilane
g and 33.0 g of phenyltrimethoxysilane were dissolved in 400.0 g of isopropyl alcohol, and a solution obtained by dissolving 2.0 g of phosphoric acid in 50.0 g of water was added to this solution under stirring.
The mixture was added dropwise over a period of time, and the mixture was stirred for 5 hours after completion of the addition.

The solution of the reaction product was applied to a substrate having aluminum formed 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 heated at 400 ° C. in a nitrogen atmosphere. After baking in an electric furnace for 1 hour, a colorless, transparent and crack-free film was obtained. When the film thickness of the coating was measured, it was 0.3
μm.

Further, when the silica-based coating film was subjected to an adhesion test according to a grid test method J1SK 5400, no peeling of the coating film was observed. Thereafter, the substrate was treated in a high-pressure steam sterilizer at 120 ° C. and 2.2 kgf / cm ² for 24 hours, and then subjected to an adhesion test by a cross-cut test method. Peeled off.

[0037]

The coating liquid for forming a silica-based film according to claim 1 or 2 is thermally stable, has good film-forming properties, and has excellent adhesion to the metal wiring of the film. The silica-based coating according to claim 3 is excellent in adhesion to metal wiring, does not peel off, is easy to form a film, and is a film of a wiring step in an SOG single-layer process in multi-layer wiring of semiconductors. It is effective for

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of a manufacturing process of a semiconductor device of the present invention.

[Explanation of symbols]

 Reference Signs List 1 semiconductor substrate 2 protective film 3 first conductor layer 4 interlayer insulating film 5 photosensitive resin layer 6A, 6B window 7 second conductor layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeru Nobe 4-3-1-1, Higashicho, Hitachi City, Ibaraki Prefecture Inside the Yamazaki Plant of Hitachi Chemical Co., Ltd. (72) Inventor Kazuhiro Enomoto 4-13 Higashicho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Chemical Co., Ltd. Yamazaki Factory

Claims (3)

[Claims] (A) General formula (I) (Wherein R represents an alkyl group having 1 to 4 carbon atoms, and n represents a positive number of 0 to 2), and (B) a general formula (II): (Wherein Ph represents a phenyl group, R represents an alkyl group having 1 to 4 carbon atoms), and an alkoxysilane oligomer obtained by hydrolysis and polycondensation of a phenylalkoxysilane compound represented by the formula (C): ) General formula (III) Wherein R is an alkyl group having 1 to 4 carbon atoms, and n is 1 or 2
A coating liquid for forming a silica-based coating comprising at least one compound selected from the group consisting of an alkoxysilane compound, an aminoalkylalkoxysilane compound and a zirconium alkoxide compound represented by the following formula: 2. An amount of at least one compound selected from the group consisting of an alkoxysilane compound, an aminoalkylalkoxysilane compound and a zirconium alkoxide compound in an amount of 1 to 10% by weight based on the alkoxysilane oligomer.
The coating solution for forming a silica-based film according to claim 1, comprising: 3. A silica-based coating obtained by applying the coating liquid according to claim 1 on a substrate surface, drying the coating liquid at 50 to 350 ° C., and then firing at 350 to 600 ° C.