JPH1150007A - Coating liquid for forming low-permittivity silica-based coating film and substrate with coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject coating liquid, having a low relative permittivity and excellent in adhesion to surfaces to be coated, mechanical strength and chemical resistance such as alkali resistance by including a reactional product of a polyether-modified silicone oil with a hydrolyze of an alkoxysilane or the like. SOLUTION: Theis coating liquid is obtained by including a reactional product prepared by mixing (A) a polyether-modified silicone oil preferably represented by the formula [R' is 0(R2 -0)a R1 , θ(R2 -θ)a (R3 -θ)b R1 R1 is H, a 1-8C hydrocarbon or the like; R2 and R3 are each a 1-8C hydrocarbon; (a) and (b) are each an integer} or the like] with (B) a hydrolyzate of an alkoxysilane represented by the formula Xn Si(OR)4-n [X is H, F, a 1-8C alkyl or the like; R is a 1-8C alkyl, an aryl or the like; (n) is 0-3] or a halogenated silane represented by the formula Xn SiX'4-n (X' is chlorine or bromine) and then preferably heat- treating the resultant mixture at <=80 deg.C for 0.5-3 hr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can form an insulating film having a low relative dielectric constant, excellent adhesion to a surface to be coated, mechanical strength, chemical resistance such as alkali resistance, and excellent crack resistance. Further, the present invention relates to a coating liquid for forming a low dielectric constant silica-based film capable of highly flattening irregularities on a surface to be coated. Further, the present invention relates to a coated substrate on which such a low dielectric constant silica-based coating is formed.

[0002]

BACKGROUND OF THE INVENTION A coating solution capable of forming a silica film having a low dielectric constant is used for, for example, a semiconductor device or a liquid crystal display device.

[0003] In a semiconductor device having a multi-layer wiring, a semiconductor device and a metal wiring layer such as an aluminum wiring layer or a metal wiring layer is insulated in order to insulate the metal wiring layer. An insulating film is provided.

When a metal wiring layer or the like is provided on a semiconductor substrate, irregularities are formed on the semiconductor substrate due to the metal wiring layer or the like, and even if an attempt is made to further form a metal wiring layer or the like on the uneven surface, disconnection occurs due to uneven steps. Sometimes. Also,
If the unevenness is larger than the range of the exposure depth of focus of the resist for forming a fine pattern, a fine pattern may not be formed. For this reason, it is necessary to highly planarize the uneven surface caused by the interlayer insulating film and various elements.

Further, in a structure having such a multi-layer wiring, in a semiconductor device having a rule of 0.3 μ or less, the spacing between metal wirings becomes narrow, so that the impedance of the metal wiring due to electrostatic induction increases and the response speed is delayed. And the power consumption increases. Therefore, between the semiconductor substrate and a metal wiring layer such as an aluminum wiring layer,
Alternatively, an interlayer insulating film provided between metal wiring layers needs to have a relative dielectric constant of 3 or less.

Further, as a color liquid crystal display device, an electrode plate composed of a TFT (thin film transistor) element and an ITO pixel electrode on a glass substrate, and a counter electrode plate in which a color filter and a transparent electrode are sequentially formed on the glass substrate There is known a matrix type color liquid crystal display device having a liquid crystal display cell having a liquid crystal layer filled between an electrode plate and a counter electrode plate. In the liquid crystal display cell as described above, the aperture ratio of the pixel is being increased in order to increase the definition of the display, and an overlapping structure of the pixel electrode and the TFT element has been proposed.

In such a liquid crystal display cell, the electric field becomes non-uniform due to crosstalk between the pixel electrode and the TFT element or a step on the surface of the pixel electrode, and the orientation of the liquid crystal material sealed in the liquid crystal display cell is disturbed. In addition, there is a tendency that pixel unevenness such as color unevenness easily occurs in a display image. For this reason,
It has been proposed that a flattening film (interlayer insulating film) having a low dielectric constant be provided between the TFT element and the ITO pixel electrode to prevent the alignment disorder of the liquid crystal material.

The interlayer insulating film used for the above purpose is generally formed on a substrate by a vapor phase growth method such as a plasma CVD method or a sputtering method or a coating method of forming an insulating film using a coating solution for forming a film. Is formed.

However, in a vapor phase growth method such as a plasma CVD method, the relative permittivity of the obtained film is said to be limited to 3.5 of a fluorine-doped silica film, and a film having a relative permittivity of 3 or less is formed. There is a problem that it is difficult to do.

A coating formed by using a coating solution composed of a fluorine-containing polyimide resin or a fluorine-based resin has a relative permittivity of about 2, but has poor adhesion to a surface to be coated and has a fine processing property. However, there are disadvantages such as poor adhesion to the resist material used for the above, poor chemical resistance and poor oxygen plasma resistance.

Further, even when a film is formed using a silica-based film-forming coating solution containing a conventionally used alkoxysilane partial hydrolyzate, the relative dielectric constant is 2.5.
Although a coating of a certain degree can be obtained, there is a drawback that adhesion to the coated surface is poor.

[0012]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems in the prior art, and has a low relative dielectric constant, as well as adhesion to a surface to be coated, mechanical strength, alkali resistance and the like. A coating liquid for forming a low dielectric constant silica-based coating film, which is capable of forming an insulating film having excellent chemical resistance and excellent crack resistance, and capable of highly flattening irregularities on a surface to be coated, and such a low dielectric constant. An object of the present invention is to provide a substrate on which a silica-based coating is formed.

[0013]

The coating liquid for forming a low dielectric constant silica-based film according to the present invention comprises (i) a polyether-modified silicone oil, and (ii) an alkoxysilane represented by the following general formula [1] or the following general formula: It is characterized by containing a reaction product with a hydrolyzate of a halogenated silane represented by [2].

X _n Si (OR) _4-n ... [1] X _n SiX ′ _4-n ... [2] (where X is a hydrogen atom, a fluorine atom or a carbon number of 1 to 8)
R represents an alkyl group having 1 to 8 carbon atoms, an aryl group or a vinyl group, X ′ represents a chlorine atom or a bromine atom, and n is an integer of 0 to 3. is there. ) The polyether-modified silicone oil is preferably a polyether-modified silicone oil represented by the following formula [3].

[0015]

Embedded image

(Wherein R ′ is —O (R ₂ —O) _a R ₁ , —O (R ₂ —O) _a (R
₃ -O) _b R ₁ , -R ₄ -O- (R ₅ -O) _c R ₁ , -R ₅ NHCH ₂ CH (OH) CH ₂ (OR ₇ ) _d
OR ₁ represents a group represented by R ₁ , wherein R ₁ is a hydrogen atom or carbon atom 1
And R _{2 to} R ₇ are hydrocarbon groups having 1 to 8 carbon atoms, and a, b, c and d are integers. The coated substrate according to the present invention is characterized by having a low dielectric constant silica-based coating having a relative dielectric constant of 3 or less formed using the above-mentioned coating solution.

[0017]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the coating liquid for forming a low dielectric constant silica-based film and the substrate with a film according to the present invention will be described in detail.

[Coating solution for forming a low dielectric constant silica-based film] The coating solution for forming a low dielectric constant silica-based film according to the present invention comprises (i) a polyether-modified silicone oil, and (ii) a general formula [1]. It contains a reaction product with an alkoxysilane represented by the formula (1) or a hydrolyzate of a halogenated silane represented by the general formula [2]. Polyether-modified silicone oil The polyether-modified silicone oil used in the present invention is one in which a group containing a polyether is introduced into the molecular structure of the silicone oil. Is mentioned.

[0019]

Embedded image

In the formula, R represents a methyl group or a phenyl group, and p and q represent integers. R ′ is —O (R ₂ —O) _a R ₁ , —O (R
₂ -O) _a (R ₃ -O) _b R ₁ , -R ₄ -O- (R ₅ -O) _c R ₁ , -R ₅ NHCH ₂ CH (OH) CH ₂
(OR ₇ ) _d represents a group represented by OR ₁ , wherein R ₁ is a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and R _{2 to} R ₇ are 1 to 8 carbon atoms.
Wherein a, b, c and d are integers. Such _{R ', -OC 3 H 6 O} (C 2 H 4 O) n H, -C 3 H 6 (OC 2 H 4) n
_{OH, -C 3 H 6 NHCH 2} CH (OH) CH 2 (OC 2 H 4) , such as _n OH and the like.

Among them, in the present invention, a side chain type polyether-modified silicone oil represented by the following general formula [3] is preferable.

[0022]

Embedded image

[0023] Such a polyether-modified silicone oil can be produced by a conventionally known method.
For example, (i) a method of adding and reacting dimethylpolysiloxane and a polyether having a carbon-carbon double bond at a molecular terminal in the presence of a platinum catalyst, (ii) a method using dimethylpolysiloxane and a polyether having a hydroxyl group at a molecular chain terminal. There are a method of performing a dehydrogenation reaction, and a method of (iii) reacting an amino-modified siloxane having a Si-C ₃ H ₆ NH ₂ group with a compound having a glycidyl group.

Such a polyether-modified silicone oil is easily decomposed by heat treatment after the formation of a silica-based film, and forms a porous material which is hydrophobic and contains many voids. Hydrolyzate of alkoxysilane or halogenated silane In the present invention, a hydrolyzate of an alkoxysilane represented by the following general formula [1] or a halogenated silane represented by the following general formula [2] is used.

[0025] X _n Si (OR) in _{4-n ... [1] X} n SiX '4-n ... [2] formula, X represents a hydrogen atom, a fluorine atom or an alkyl group having 1 to 8 carbon atoms, an aryl group, or X represents a vinyl group, R represents an alkyl group having 1 to 8 carbon atoms, an aryl group or a vinyl group, X ′ represents a chlorine atom or a bromine atom, and n is an integer of 0 to 3.

Specific examples of the alkoxysilane represented by the general formula [1] include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraoctylsilane, methyltrimethoxysilane, methyltriethoxysilane. Silane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyl Triethoxysilane, trimethoxysilane, triethoxysilane, triisopropoxysilane, fluorotrimethoxysilane, fluorotriethoxysilane, dimethyldimethoxysilane, dimethyl Distearate silane, diethyl dimethoxy silane, diethyl diethoxy silane, dimethoxy silane, di-silane, difluoromethyl dimethoxysilane, difluoro diethoxy silane, trifluoromethyl trimethoxy silane, trifluoromethyl triethoxy silane.

The halogenated silane represented by the general formula [2] includes trichlorosilane, tribromosilane, dichlorosilane, fluorotrichlorosilane, fluorotribromosilane and the like.

The hydrolyzate used in the present invention is an alkoxysilane represented by the above-mentioned general formula [1] or the above-mentioned general formula [2]
Is obtained by hydrolysis and polycondensation in the presence of water, an organic solvent and a catalyst. As such a hydrolysis / polycondensation method, a conventionally known method can be used.

Examples of the organic solvent include alcohols, ketones, ethers, esters and the like. Specific examples include alcohols such as methanol, ethanol, propanol and butanol, and ketones such as methyl ethyl ketone and methyl isobutyl ketone. Glycol ethers such as methyl cellosolve, ethyl cellosolve and propylene glycol monopropyl ether; glycols such as ethylene glycol, propylene glycol and hexylene glycol; esters such as methyl acetate, ethyl acetate, methyl lactate and ethyl lactate are used. You.

Examples of the catalyst include inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid; organic acids such as acetic acid, oxalic acid and toluenesulfonic acid; compounds which are acidic in aqueous solutions such as metal soaps; ammonia, amines and alkali metal hydrides. And quaternary ammonium compounds and basic compounds such as amine-based coupling agents.

The water required for the hydrolysis is usually 0.1 to 5 mol, preferably 0.1 mol, per 1 mol of the Si-OR group constituting the alkoxysilane or the Si-X 'group constituting the halogenated silane. It is used in an amount of 1 to 2 mol. The amount of the catalyst to be added is preferably 0.001 to 1 mol per mol of alkoxysilane or halogenated silane.

The hydrolyzate thus obtained has a number average molecular weight of 1,000 to 50,000, preferably 200 to 50,000.
Desirably, it is 0 to 20,000 (molecular weight in terms of polystyrene). Polyether-modified silicone oil and the hydrolyzate
In the present invention, the polyether-modified silicone oil
A reaction product of (A) and the hydrolyzate (B) is used.

This reaction product is obtained by reacting and bonding a polyether group in a polyether-modified silicone oil with a hydrolyzate of an alkoxysilane or a halogenated silane, and the polyether-modified silicone oil (A) It is considered that it was introduced into the skeleton of the hydrolyzate (B).

After mixing the polyether modified silicone oil (A) and the hydrolyzate (B),
At a temperature of 0 ° C. or less, preferably 80 ° C. or less, for 0.5 to 20 hours,
It is preferably obtained by performing a heat treatment for 0.5 to 3 hours.

At this time, the weight ratio (B) / (A) of the polyether-modified silicone oil (A) and the hydrolyzate (B) is 1 to
It is desirably 50, preferably 1-20. When the weight ratio (B) / (A) is smaller than 1, the adhesion to the surface to be coated and
Mechanical strength and chemical resistance (such as alkali resistance) are poor, and crack resistance and flattening performance of a coated surface may be deteriorated.

When a silica-based coating is formed using such a reactant, the polyether-modified silicone oil (A) component in the reactant is easily thermally decomposed by heat treatment after film formation, and the hydrophobic porous film is formed. Hydrolysate (B) component in the reaction product prevents water from re-adsorbing to the voids, and has excellent heat resistance, low dielectric constant, and little change over time. A coating can be formed.

A coating solution containing such a reactant is applied on a substrate, and is then placed under an oxygen-containing gas atmosphere (for example, 1000 rp).
m-oxygen-containing nitrogen gas), the silica-based film obtained by calcining at 400 ° C. was allowed to stand at room temperature for one week, and the FT-IR spectrum was measured. Therefore, the relative permittivity value of the obtained coating does not increase. Preparation of coating solution for forming low dielectric constant silica-based film The coating solution for forming low dielectric constant silica-based film according to the present invention is obtained by mixing the hydrolyzate of the alkoxysilane or halogenated silane with the polyether-modified silicone oil. After heat treatment, the solvent was replaced with methyl isobutyl ketone using a rotary evaporator, and the generated alcohol and water were completely removed.
It is obtained by adjusting to 40% by weight, preferably 10 to 30% by weight.

The coating liquid for forming a silica film having a low dielectric constant may contain a filler. Examples of the filler include silica, alumina, titanium dioxide, zinc oxide, tungsten oxide, and oxide. Examples include ruthenium, potassium titanate, barium titanate, barium sulfate, calcium carbonate, mica, kaolin, and talc.

[Substrate with low dielectric constant silica-based coating] The substrate with low dielectric constant silica-based coating according to the present invention has a low dielectric constant of 3 or less formed using the above-mentioned coating solution. It is a substrate having a high silica coating.

Such a coated substrate can be obtained by applying the above-mentioned coating solution to the surface of various substrates and then heating. Examples of the coating method include a spray method, a spin coating method, a dip coating method, a roll coating method, and a transfer printing method. The heating temperature after coating is usually 300 to 450 ° C, preferably 350 to 400 ° C. This heating is preferably performed in an atmosphere of an inert gas such as nitrogen, so that a film having a low relative dielectric constant can be obtained.

At the time of such heat curing treatment, curing treatment of the coating film such as ultraviolet irradiation or electron beam irradiation or plasma treatment may be used in combination. The film thickness of the low dielectric constant silica-based coating formed in this manner varies depending on the base material on which the coating is formed, its purpose, and the like.
In the case of a multilayer wiring interlayer insulating film, the thickness is usually about 3000 to 5000 °.

Examples of the substrate with a low dielectric constant silica-based coating according to the present invention include semiconductor devices, liquid crystal display devices, LSI devices having a multilayer wiring structure, printed circuit boards, hybrid ICs, and alumina substrates. Parts, a photomask with a phase shifter, a three-layer resist, and the like.

In a semiconductor device, a low dielectric constant silica-based coating is formed on a silicon substrate, between wiring layers of a multilayer wiring structure, on an element surface, or on a PN junction. In the liquid crystal display cell of the color liquid crystal display device, the low dielectric constant silica-based coating is formed between the TFT element and the ITO pixel electrode.

Further, in the phase shifter and the three-layer resist of the photomask with the phase shifter, a low dielectric constant silica-based film is formed in the intermediate layer. Furthermore, in the above electronic component, a low dielectric constant silica-based coating is formed as a flattening film.

[0045]

According to the coating liquid for forming a silica-based film according to the present invention, the relative dielectric constant is low, and the coating liquid is excellent in adhesion to a surface to be coated, mechanical strength, and chemical resistance such as alkali resistance.
At the same time, an insulating film having excellent crack resistance can be formed, and the unevenness of the surface to be coated can be highly flattened.

The substrate with a low dielectric constant silica-based coating according to the present invention has a low relative dielectric constant of 3 or less, is excellent in adhesion to a surface to be coated, mechanical strength, chemical resistance such as alkali resistance, and It has a coating excellent in crack resistance and heat resistance, and has a highly flattened unevenness on the surface to be coated.

[0047]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the examples.

[0048]

[Production Example] 1. Hydrolysis of alkoxysilane and halogenated silane
Preparation of digest (1) Triethoxysilane 250 g and methyl isobutyl ketone 7
50 g of the mixture and 100% of a 0.01% by weight aqueous hydrochloric acid solution.
0 g was added and reacted at 50 ° C. for 1 hour with stirring. After standing, the upper layer of the methyl isobutyl ketone solution was separated to obtain a hydrolyzate (A).

(2) Trichlorosilane is hydrolyzed in a toluene solvent by using toluenesulfonic acid hydrate to hydrolyze trichlorosilane, and the obtained hydrogensilsesquioxane is converted to methyl isobutyl. Dissolved in ketone (hydrolysate (B)). 2. Preparation of Coating Solution for Forming Coating Film The hydrolyzates ((A) and (B)) of alkoxysilane and halogenated silane obtained as described above and polyether-modified silicone oil (KF61, manufactured by Shin-Etsu Silicone Co., Ltd.)
8) was mixed in the proportions shown in Table 1 and heat-treated at 50 ° C. for 5 hours. Thereafter, the solvent was replaced again with methyl isobutyl ketone by a rotary evaporator to completely remove the alcohol and water generated by the heat treatment, thereby preparing a coating solution for forming a film having a solid concentration of 20% by weight.

[0050]

[Table 1]

[0051]

Examples 1 to 4 and Comparative Examples 1 and 2 The coating liquids for film formation prepared in the semiconductor device manufacturing examples were applied by spin coating to a semiconductor substrate provided with metal wiring of a minimum 0.25 μ rule. And dried at 250 ° C. for 3 minutes. Thereafter, the mixture was fired at 400 ° C. for 30 minutes in a nitrogen atmosphere and a nitrogen gas atmosphere containing 1000 rpm to form a silica-based coating. Each of the formed silica-based coatings was 5000 °. Further, an upper metal wiring was formed on these films, and a semiconductor device was manufactured.

Table 2 shows the results of measuring the flattening characteristics and the relative dielectric constant of the silica-based coating of each of the semiconductor devices thus obtained. Note that the flattening characteristics were obtained by observing a cross section of the substrate after forming the film with an SEM-type electron microscope, and measuring the relative permittivity by a mercury probe method.

[0053]

[Table 2]

As can be seen from Table 2, the relative dielectric constant of the silica-based coating of the example was hardly changed even after firing in a nitrogen gas atmosphere containing 1,000 rpm of oxygen, as compared with the silica-based coating of the comparative example.

[0055]

Examples 5 to 8, Comparative Examples 3 and 4 The coating liquid for film formation prepared in the production example of a color liquid crystal display device was applied on a glass substrate on which a TFT element was formed, and was subjected to a heat treatment to obtain a low dielectric constant. A silica-based coating was formed. After that, upper layer ITO
A pixel electrode and a polyimide alignment film were formed, and bonded to a counter electrode plate on which a color filter, a transparent electrode, and a polyimide alignment film were sequentially formed on a glass substrate. Then, a liquid crystal layer was filled in the meantime to prepare a matrix type color liquid crystal display device having a liquid crystal display cell.

The flatness characteristics of the silica-based coating of the color liquid crystal display device thus obtained, the presence or absence of crosstalk,
Table 3 shows the display characteristics. The presence or absence of crosstalk was visually determined, and the display characteristics were determined by luminance and contrast ratio.

[0057]

[Table 3]

As can be seen from Table 3, the silica-based coating of the example has no crosstalk and is excellent in display characteristics as compared with the silica-based coating of the comparative example.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiro Komatsu 13-2 Kitaminato-cho, Wakamatsu-ku, Kitakyushu-shi, Fukuoka

Claims (3)

[Claims] 1. A method comprising: (i) a polyether-modified silicone oil and (ii) a hydrolyzate of an alkoxysilane represented by the following general formula [1] or a halogenated silane represented by the following general formula [2]: A coating solution for forming a low dielectric constant silica-based film, comprising a reactant. _{X n Si (OR) 4-} n ... [1] X n SiX '4-n ... [2] ( wherein, X represents a hydrogen atom, 1-8 fluorine atoms or carbon atoms
R represents an alkyl group having 1 to 8 carbon atoms, an aryl group or a vinyl group, X ′ represents a chlorine atom or a bromine atom, and n is an integer of 0 to 3. is there. ) 2. The coating liquid according to claim 1, wherein the polyether-modified silicone oil is a polyether-modified silicone oil represented by the following formula [3]. Embedded image (Wherein R 'is -O (R ₂ -O) _a R ₁ , -O (R ₂ -O) _a (R ₃ -O) _b R ₁ , -R ₄
—O— (R ₅ —O) _c R ₁ , —R ₅ NHCH ₂ CH (OH) CH ₂ (OR ₇ ) _d OR ₁ represents a group represented by R ₁ , wherein R ₁ is a hydrogen atom or a group having 1 to 8 carbon atoms. Wherein R _{2 to} R ₇ are hydrocarbon groups having 1 to 8 carbon atoms, and a, b, c and d are integers. ) 3. A coated substrate comprising a low dielectric constant silica-based coating having a relative dielectric constant of 3 or less, formed using the coating solution according to claim 1 or 2.