JP3139230B2 - Coating solution for forming silica-based film and substrate with film - Google Patents

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, and more particularly, to a coating solution having excellent adhesion to a surface to be coated, mechanical strength, chemical resistance such as alkali resistance, and at the same time, dense and crack resistant. The present invention relates to a coating liquid for forming a silica-based film, which has excellent properties and is capable of highly flattening irregularities on a surface to be coated, and a coated substrate on which such a silica-based film is formed.

[0002]

BACKGROUND OF THE INVENTION Conventionally, silica-based coatings have been used in the following fields. 1) Semiconductor Device In a semiconductor device, an insulating film is provided between a semiconductor substrate and a metal wiring layer such as an aluminum wiring layer or between metal wiring layers to insulate them. Further, in order to protect the PN junction semiconductor provided on the semiconductor substrate and various elements such as a capacitor element and a resistance element, these elements are covered with an insulating film.

When a metal wiring layer or the like is provided on a semiconductor substrate, unevenness is generated on the semiconductor substrate by the metal wiring layer or the like. Even if an attempt is made to further form a metal wiring layer or the like on the uneven surface, disconnection may occur due to uneven steps. Therefore, the insulating film formed between the semiconductor substrate and the metal wiring layer as described above, between the metal wiring layers, and the insulating film covering the various elements are formed by the metal wiring layer and the various elements as described above. It is necessary to highly flatten the uneven surface.

[0004] In such a semiconductor device, a silica-based coating is used as an insulating film. 2) Liquid crystal display device In a liquid crystal display cell of a liquid crystal display device, a transparent electrode plate having an ITO film on a glass substrate is often used.
In a liquid crystal display cell using such a transparent electrode plate, during use, an alkali component such as Na contained in a glass substrate migrates into an ITO film, or furthermore, an ITO component.
May elute into the liquid crystal through the film. In order to prevent such an alkali component from migrating into the ITO film, a transparent electrode plate provided with an alkali passivation film between the glass substrate and the ITO film is also used.

Further, in order to improve the orientation of the liquid crystal material enclosed in the liquid crystal display cell, an orientation film is further formed on a transparent electrode of a transparent electrode plate, for example, a transparent electrode made of an ITO film. I have. In a transparent electrode plate having such an alignment film, an insulating film may be provided between the transparent electrode and the alignment film in order to increase the life of the alignment film.

As a color liquid crystal display device, an electrode plate having a pixel electrode composed of a TFT (thin film transistor) on a glass substrate and a counter electrode plate on which a color filter and a transparent electrode are sequentially formed on a glass substrate are provided. A matrix type color liquid crystal display device including a liquid crystal display cell having a liquid crystal layer filled between an electrode plate and a counter electrode plate is known.

In the liquid crystal display cell as described above, the pixel electrode protrudes from the electrode plate and the color filter protrudes from the counter electrode plate, and each electrode surface has a step. If there is a step on the electrode surface in this way, the cell gap becomes non-uniform, and the orientation of the liquid crystal material sealed inside the liquid crystal display cell is disturbed or the display image is not displayed as compared with the case where the cell gap is uniform. Pixel unevenness such as color unevenness tends to easily occur.

For this reason, JP-A-2-242226 discloses that a polyimide resin film, an acrylic resin film, or a silica film is formed on a pixel electrode of an electrode plate and a color filter of a counter electrode plate by a coating method. In addition, it has been proposed to flatten an uneven surface caused by a pixel electrode or a color filter.

In such a liquid crystal display device, a silica-based coating is used as the insulating film and the alkali passivation film as described above. 3) Photomask with phase shifter In order to form a high-resolution uneven pattern on the substrate by lithographic method, a phase shifter for shifting the phase of the irradiation light is provided on the photomask, thereby forming the uneven pattern formed on the substrate. There is a method for improving the resolution (Nikkei Micro Devices No. 71, 52 to 58, (5), 199).
1).

A silica-based coating is used as such a phase shifter. Silica-based coatings used in the fields described above are generally formed on a substrate by a vapor deposition method such as a CVD method or a sputtering method, or a coating method of forming a silica-based coating using a coating solution for forming a silica-based coating. Is formed.

However, the method of forming a silica-based film by a vapor phase growth method is troublesome and requires large equipment. Further, when a silica-based film is formed on an uneven surface, the silica-based film is not used. The uneven surface cannot be flattened.

On the other hand, since the above-mentioned problems can be solved by forming a silica-based coating by a coating method, formation of a silica-based coating by a coating method has been widely performed in recent years.

Conventionally, when a silica-based coating is formed by such a coating method, a coating solution for forming a silica-based coating in which the coating forming component is a condensation polymer of an alkoxysilane partial hydrolyzate has been used. Was. The condensation polymerization product of the partially hydrolyzed alkoxysilane is obtained by dissolving the alkoxysilane in an organic solvent such as alcohol, ketone or ester, and then adding the acid or base as a catalyst and water to the alkoxysilane solution to partially convert the alkoxysilane. Hydrolysis,
Then, it can be obtained by condensation polymerization.

However, when a coating solution for forming a silica-based film, in which the film-forming component is a condensation polymer of an alkoxysilane partial hydrolyzate, is applied and dried on the substrate, alkoxysilane is contained in the obtained film. It remains. Therefore, when this film is fired, organic groups such as alkyl groups and alkoxy groups contained in alkoxysilane molecules are decomposed in the film at the time of firing, and pinholes and voids are formed in the film due to the decomposition of the organic groups. It is difficult to obtain a dense and silica-based coating. Further, during the condensation of the partial hydrolyzate of the alkoxysilane, silanol groups other than at the ends of the condensate undergo a dehydration reaction, whereby crosslinking of the condensate proceeds. For this reason, in the process of forming the silica-based coating, the shrinkage stress of the coating increases according to the degree of crosslinking of the condensate, and the coating is cracked. That is, when a coating solution for forming a silica-based film is used in which the film-forming component is a condensation polymer of an alkoxysilane partial hydrolyzate, it is difficult to obtain a silica-based film having excellent crack resistance.

On the other hand, in recent years, a coating solution for forming a silica-based film containing a cyclosilazane polymer or polysilazane has been proposed (see JP-A-62-88327, JP-A-1-203476, etc.). When a silica-based coating is formed using these coating solutions, the denseness and crack resistance of the silica-based coating can be improved to some extent.

However, the silica-based coating formed from the above-mentioned coating solution containing a cyclosilazane polymer or polysilazane has the following problems. The cyclosilazane polymer or polysilazane has a silazane skeleton represented by the following formula (I).

[0017]

Embedded image

When these coating solutions are applied on a substrate and the resulting coating film is heated and baked to obtain a silica-based coating, the silazane skeleton is oxidized to form a siloxane skeleton.

[0019]

Embedded image

Changes to However, if the silazane skeleton remains in the silica-based coating obtained without performing the oxidation reaction sufficiently, the denseness of the silica-based coating is reduced or the silica-based coating is reduced according to the remaining amount of the silazane skeleton. May absorb moisture. Further, when the silica-based coating having the silazane skeleton remaining thereon is fired, the silazane skeleton may be decomposed and ammonia gas may be released.

The silica-based coating formed from the coating solution containing the cyclosilazane polymer or the polysilazane as described above has insufficient denseness, or the above-mentioned silica gas is released due to the ammonia gas released from the silica-based coating. In such a semiconductor device, a metal wiring layer may be corroded, and in a liquid crystal display device, a liquid crystal material in a liquid crystal display cell may be deteriorated. Furthermore, if the silazane skeleton remains in the silica-based coating, the phase shifter may be gradually deteriorated by exposure light.

For this reason, when a silica-based coating is formed from a coating solution containing a cyclosilazane polymer or polysilazane, the coating is heated with an oxygen plasma so that the silazane skeleton does not remain in the obtained silica-based coating. It has been performed under irradiation or in a steam atmosphere, and then the coating film has been fired in air at a temperature of 500 ° C. or higher. Further, when a silica-based coating is formed from a coating solution containing cyclosilazane, if the firing of the coating is performed at a temperature of 900 ° C. or higher, a silica-based coating containing almost no silazane skeleton could not be obtained. .

If it is attempted to form a silica-based coating under such severe oxidation conditions, the semiconductor device, the transparent electrode and the like are also exposed to high temperatures, which is not preferable. On the other hand, the present applicant has proposed a silica using a specific polysilazane in which R _{1 to} R _{3 in the} formula [I] are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms as a film-forming component. A coating liquid for forming a system film is applied on the surface to be coated, and the obtained film is dried in air at a low temperature of about 150 ° C., and then fired at a temperature of 800 ° C. or less, so that a low nitrogen content is obtained. It has been found that a silica-based coating can be obtained. In particular, when all of R _{1 to} R ₃ are hydrogen atoms, the coating is fired at a temperature of about 450 ° C. to obtain a silica-based coating having a low nitrogen content.

The present inventors have further studied based on the above findings. A) Modification in which such a specific polysilazane is modified with a specific carboxylic acid and / or carboxylic acid ester A coating solution containing polysilazane is applied on the surface to be coated, and the obtained coating film is dried and then baked to form a silica-based coating.From the coating solution containing only polysilazane as a coating component, a silica-based coating is formed. A silica-based coating having a low nitrogen content can be obtained at a lower firing temperature as compared with the case where the coating is formed in the same manner.
Excellent adhesion to the surface to be coated, mechanical strength, chemical resistance such as alkali resistance, moisture resistance and crack resistance, and at the same time, it is a dense insulating film with almost no voids and pinholes, c) unevenness When a coating solution containing the above-mentioned modified polysilazane is applied on the surface to form a film, the uneven surface is highly planarized as in the case where the film-forming component is a conventional polysilazane; d. Therefore, it has been found that when the above-mentioned coated substrate is manufactured using the coating solution containing the modified polysilazane as described above, a product having more excellent performance than before can be obtained. The invention has been completed.

[0025]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems in the prior art, and is excellent in adhesion to a surface to be coated, mechanical strength, chemical resistance such as alkali resistance, etc. At the same time, a dense insulating film with excellent crack resistance
It is an object of the present invention to provide a coating liquid for forming a silica-based film, which can be formed at a firing temperature of 0 ° C. or less and can highly flatten the unevenness of the surface to be coated, and a coated substrate having such excellent properties. The purpose is.

[0026]

The coating solution for forming a silica-based film according to the present invention has the following general formula [I]:

[0027]

Embedded image

(Wherein R ¹ , R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.) One kind of polysilazane having at least a repeating unit represented by the formula: Or two or more kinds, and the following general formula [II] RCOOR '... [II] (wherein, R is a hydrocarbon group having 1 to 30 carbon atoms, and R' is a hydrogen atom or a carbon atom having 1 to A carboxylic acid and / or a carboxylic acid ester represented by the formula : Si / N
The modified polysilazane having an atomic ratio in the range of 1.07 to 1.30 is characterized by containing the modified polysilazane as a film-forming component .

Further, the coated substrate according to the present invention is characterized by having a silica-based coating formed using the above-mentioned coating solution.

[0030]

DETAILED DESCRIPTION OF THE INVENTION The coating liquid for forming a silica-based film according to the present invention will be specifically described below. Coating Solution for Forming Silica-Based Film The coating solution for forming a silica-based film according to the present invention comprises one or more polysilazanes having at least a repeating unit represented by the above general formula [I], It contains a modified polysilazane modified with the carboxylic acid and / or carboxylic acid ester represented by [II].

Among them, the polysilazane used in the present invention is such that R ₁ , R ₂ and R _{3 in} the above formula [I] are each a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Methyl, ethyl or propyl groups are preferred.

In the polysilazane used in the present invention, R ₁ , R ₂ and R _{3 in} the above formula [I] are all hydrogen atoms, 55 to 65% by weight of silicon atoms and 20% of nitrogen atoms in one molecule. ~ 30% by weight, hydrogen atom is 10 ~ 1
Particular preference is given to inorganic polysilazanes which are present in an amount such as to be 5% by weight. Such an inorganic polysilazane can be produced, for example, according to the methods disclosed in JP-B-63-16325 and U.S. Pat. No. 4,397,828.

The polysilazane having a repeating unit represented by the above formula [I] may be linear or cyclic, and contains a mixture of linear polysilazane and cyclic polysilazane. May be.

The weight average molecular weight of the polysilazane used in the present invention is from 500 to 10,000, preferably from 1,0 to 10,000.
It is desirable to be in the range of 00 to 4,000. When the weight average molecular weight is less than 500, the low molecular weight compound volatilizes in a drying step when forming a silica-based coating from a coating solution, and the coating shrinks greatly in a subsequent baking step. On the other hand, when the molecular weight exceeds 10,000, the fluidity of the coating liquid decreases. Therefore, in any of the above cases, when the uneven surface is covered with the coating, it is difficult to sufficiently flatten the uneven surface with the coating. The polysilazane has an Si / N ratio (atomic ratio) of 1.0 to 1.0.
It is desirably in the range of 3.

Further, the coating liquid for forming a silica-based film according to the present invention contains a polysilazane whose low molecular weight polysilazane having a molecular weight of 1,000 or less is 10 to 40% by weight, preferably 15 to 40% by weight of the whole polysilazane. It is desirable to use When the low molecular weight polysilazane is less than 10% by weight, the fluidity of the coating solution is reduced, and the surface smoothness of the silica-based insulating film obtained from the coating solution may be reduced. On the other hand, if the low-molecular-weight polysilazane exceeds 40% by weight, the amount of low-molecular-weight compounds volatilized in the drying step when forming a silica-based coating from a coating solution increases, and the coating greatly shrinks in the subsequent firing step. The surface smoothness of the silica-based coating obtained from the coating solution may be reduced.

The carboxylic acid and carboxylic acid ester used in the present invention are represented by the above general formula [II]. In the above formula [II], R is a hydrocarbon group having 1 to 30 carbon atoms.

Examples of the carboxylic acid or carboxylic acid ester represented by the above formula [II] include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, pivalic acid, valeric acid, isovaleric acid, caproic acid, 2-ethylbutyric acid, caprylic acid, 2-ethylhexanoic acid, oleic acid, linoleic acid, stearic acid, benzoic acid, oxalic acid, malonic acid, maleic acid, tartaric acid, citric acid, phthalic acid, acetic anhydride, propionic anhydride, Butyric anhydride, formate, acetate, propionate, butyrate, isobutyrate, isovalerate, stearate,
Benzoate, oxalate, malonate, maleate, tartrate, citrate, phthalate and the like can be mentioned.

The coating solution for forming a silica-based film according to the present invention is prepared as follows. i) The polysilazane as described above is mixed with a carboxylic acid and / or a carboxylic acid ester in an organic solvent.

The organic solvent is not particularly limited as long as it can dissolve a mixture of polysilazane and carboxylic acid and / or carboxylic acid ester. Specific examples thereof include ketones such as methyl ethyl ketone, and methyl cellosolve. Glycol ethers, hydrocarbons such as hexane and octane, cyclic hydrocarbons such as cyclohexane, toluene and xylene, and ethers such as ethyl ether, ethyl butyl ether, dioxane and tetrahydrofuran. These organic solvents are used alone or in combination of two or more.

When the polysilazane and the carboxylic acid and / or carboxylic acid ester were mixed in an organic solvent as described above, the Si—N bond of the polysilazane reacted with the carboxyl group, and the Si—N bond of the polysilazane was cleaved. A modified polysilazane is formed.

The reaction between the polysilazane and the carboxyl group is carried out at any temperature below the boiling point of the solvent. Also,
The compounding ratio of polysilazane to carboxylic acid and / or carboxylic acid ester used in this reaction is preferably adjusted to a molar ratio of 99.9 / 0.1 to 1/2. If this molar ratio exceeds 99.9 / 0.1, the effect of modifying polysilazane is almost negligible.
If it is less than 2, preferred properties of polysilazane tend to be impaired. ii) After the completion of the above-mentioned polysilazane reforming reaction, the resulting modified polysilazane has a weight average molecular weight of 10
If less than 00, after replacing the organic solvent in the reaction solution with a basic solvent, a polymerization reaction of the modified polysilazane is performed,
The molecular weight of the modified polysilazane is adjusted to a preferred range.
The basic solvent used at this time is not particularly limited as long as it is a basic solvent, but pyridine, picoline, trimethylphosphine, triethylphosphine, furan,
Dioxane is preferred, and pyridine is particularly preferred. The polymerization reaction of the modified polysilazane is performed at an arbitrary temperature equal to or lower than the boiling point of the basic solvent in an atmosphere of an inert gas such as nitrogen or argon while blowing nitrogen gas into the basic solvent.

The resinous material is obtained by removing the solvent from the liquid containing the modified polysilazane obtained as described above by distillation under reduced pressure or the like. iii) The coating liquid for forming a silica-based film according to the present invention is basically obtained by dissolving the obtained resinous substance in an organic solvent so that the solid content concentration becomes 3 to 40% by weight.

The organic solvent used at this time is not particularly limited as long as it disperses or dissolves the above resinous substance and imparts fluidity to the coating liquid.
Examples include hydrocarbons such as hexane, octane, cyclohexane, toluene, and xylene, and ethers such as ethyl ether, ethyl butyl ether, dibutyl ether, dioxane, and tetrahydrofuran. These organic solvents are used alone or in combination of two or more.

The organic solvent used in the coating solution according to the present invention is preferably an organic solvent having a water solubility of 0.5% by weight or less. When such an organic solvent is used for the coating liquid, it is possible to prevent the polysilazane or the like in the coating liquid from being hydrolyzed to cause hydrolysis, thereby obtaining a coating liquid having a long pot life.

The weight average molecular weight of the resinous modified polysilazane obtained by the above method is from 500 to 10,000.
0, preferably in the range of 1,000 to 4,000. When the weight average molecular weight is less than 500, the low molecular weight compound volatilizes in a drying step when forming a silica-based coating from a coating solution, and the coating shrinks greatly in a subsequent baking step. Moreover, the molecular weight is 10,0.
If it exceeds 00, the fluidity of the coating liquid will decrease. Therefore, in any case, when the uneven surface is covered with the coating, it is difficult to sufficiently flatten the uneven surface with the coating. The Si / N ratio (atomic ratio) of this resinous material is
Like the polysilazane, it is desirable that it is in the range of 1.07 to 1.30 .

When the silica-based coating is formed using the coating solution for forming a silica-based coating according to the present invention as described above, compared with the case where a silica-based coating is formed using a conventional polysilazane-based coating solution as a coating-forming component. Then, the coating film obtained from the coating solution is dried and then excellent in compactness even when baked at a lower temperature than in the case of the conventional polysilazane-based coating solution, and has excellent flatness with little shrinkage stress and voids. Is obtained.

Particularly, the coating solution for forming a silica-based film according to the present invention is represented by the above formula [I], wherein R ₁ , R
_In the case of a coating solution containing a modified polysilazane obtained by modifying an inorganic polysilazane in which all ₂ and R ₃ are hydrogen atoms with the above carboxylic acid and / or carboxylic acid ester, a coating film which is denser and has excellent crack resistance Can be obtained.

In other words, when a silica-based coating is formed from a coating solution containing the above-mentioned modified inorganic polysilazane in which most of the film-forming components are formed, the coating formed in the drying / firing step when the silica-based coating is formed. Is suppressed by volume expansion when the Si—H bond in the modified polysilazane changes to a Si—O bond. For this reason, when a coating is formed from a coating liquid containing the above-mentioned modified inorganic polysilazane in which most of the components for forming the coating are formed, the shrinkage stress during the formation of the coating is reduced, and the occurrence of cracks is suppressed. Therefore,
It is preferable to use a coating liquid in which most of the film forming components are composed of the modified inorganic polysilazane as described above, particularly when forming a thick silica-based insulating film.

The substrate with a film according to the present invention may be, for example, a semiconductor device, a liquid crystal display, a photomask with a phase shifter, an LSI element having a multilayer wiring structure, or the like as described above. Examples include printed circuit boards, hybrid ICs, electronic components such as alumina substrates, and three-layer resists.

That is, in the above semiconductor device,
Between the semiconductor substrate and the metal wiring layer, a silica-based coating is formed between the metal wiring layers, the PN junction semiconductor provided on the semiconductor substrate, and various elements such as a capacitor element and a resistance element are covered with the silica-based coating, The uneven surface formed by these elements is flattened.

Further, in the liquid crystal display cell of the liquid crystal display device, the transparent electrode plate has an alignment film between the transparent substrate and the transparent electrode and the transparent electrode plate having an alignment film on the transparent electrode. In a liquid crystal display cell in a color liquid crystal display device, a silica-based coating is formed, and a silica-based coating is formed on a pixel electrode of an electrode plate and a color filter of a counter electrode plate, and the uneven surface formed by the pixel electrode and the color filter is formed. Are flattened by the silica-based coating.

Further, the phase shifter of the photomask with a phase shifter and the intermediate layer of the three-layer resist are composed of a silica-based coating, and the above electronic components are provided with the silica-based coating similarly to the semiconductor device. The application surface is flattened by the silica-based coating.

The coated substrate according to the present invention is formed using a coating solution containing a modified polysilazane obtained by reacting one or more polysilazanes with the carboxylic acid and / or carboxylic acid ester. It has a silica-based coating. The thickness of the silica-based coating is usually 0.05
２2μ, preferably about 0.1-1μ.

Such a silica-based coating is prepared, for example, by applying the above-mentioned coating solution for forming a silica-based coating according to the present invention to a surface to be coated on a substrate, for example, a transparent electrode plate when a liquid crystal display device is manufactured. It can be obtained by applying to the transparent electrode surface by various methods such as spraying, spin coating, dipping, roll coating, screen printing, and transfer printing, and then drying and firing the obtained coating. it can.

In the heat curing treatment of the coating film, a curing treatment of the coating film by irradiation with ultraviolet rays or electron beams may be used together.

[0056]

According to the coating solution for forming a film according to the present invention, there are almost no voids, pinholes, etc., and it is dense and has chemical resistance such as adhesion to a surface to be coated, mechanical strength and alkali resistance. It is possible to form a silica-based insulating film having excellent properties, moisture resistance, insulating properties, and the like at a firing temperature of 350 ° C. or lower, and to highly flatten the unevenness of the surface to be coated.

That is, when a silica-based film is formed from a conventional polysilazane-based coating solution as a film-forming component,
When the thermal decomposition temperature of the -N-Si bond is high and dried and fired at a temperature of 500 ° C or less, nitrogen atoms remain in the obtained silica-based coating, When a silica-based coating is formed from the coating solution at the same drying and firing temperature, almost no nitrogen atoms remain in the obtained silica-based coating. Further, the silica-based coating obtained from the coating liquid for forming a coating according to the present invention in this manner has higher chemical resistance such as denseness and alkali resistance than a silica-based coating obtained from a conventional polysilazane-based coating liquid. Excellent in nature.

As described above, even when the coating solution for forming a coating film according to the present invention is applied to the coating surface and the obtained coating film is dried and fired at a relatively low temperature of 350 ° C. or less, almost no nitrogen atoms remain. The reason for obtaining a silica-based coating is presumed as follows.

That is, when the polysilazane is modified with the carboxylic acid and / or carboxylic acid ester as described above, the nitrogen atom part firmly bonded to the silicon atom in the polysilazane molecule is replaced with a carboxyl group, The bond formed between the atom and two adjacent silicon atoms is cleaved. This may be due to the disappearance of the Si-N-Si bond part having a relatively large bond energy.

Further, according to the present invention, a silica-based film is formed between a semiconductor substrate and a metal wiring layer and between metal wiring layers, and a PN junction semiconductor provided on the semiconductor substrate, a capacitor element, a resistance element, and the like. Various devices are coated with a silica-based coating, and the uneven surface formed by these devices is flattened, between a glass substrate and a transparent electrode, such as Na contained in the glass substrate. A liquid crystal having a silica-based coating as a so-called alkali passivation film that can prevent an alkali component from migrating into the transparent electrode or eluting into the liquid crystal sealed between the transparent electrodes through the transparent electrode. The display device further includes a transparent electrode plate having a silica-based coating formed between the transparent electrode and the alignment film of the transparent electrode plate having an alignment film on the transparent electrode. A liquid crystal display device having a crystal display cell, an electrode plate having a silica-based coating formed on a pixel electrode, and a counter electrode plate having a silica-based coating formed on a color filter, and formed by the pixel electrode and the color filter. A color liquid crystal display device having a liquid crystal display cell in which the uneven surface is flattened by the silica-based coating, a photomask with a phase shifter such that the phase shifter is a silica-based coating, and the intermediate layer is a silica-based coating. Electronic components having a three-layer resist and a silica-based coating provided in the same manner as a semiconductor device, and the surface to which the silica-based insulating film is applied is flattened by the silica-based coating, such as an LSI element having a multilayer wiring structure and a print. Coated substrates such as circuit boards, hybrid ICs, and alumina substrates can be provided with good yield.

[0061]

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

[0062]

[Production Example]

1) Synthesis of Polysilazane A Polysilazane A was synthesized by the following production method according to the production method described in JP-B-63-16325.

600 ml of pyridine was placed in a reactor placed in a thermostat at a temperature of 0 ° C., and 28.3 g of dichlorosilane was added with stirring to form a complex (pyridine adduct). Next, ammonia was blown into the liquid containing the pyridine adduct for 2 hours to obtain a liquid containing a reaction product.
After the precipitate contained in this solution was removed by filtration, the filtrate was heated at 80 ° C. for 10 hours, and then pyridine was removed from the filtrate under reduced pressure, whereby resinous polysilazane A was placed in the reactor. Obtained. 2) Synthesis of polysilazane B 300 ml of methylene chloride was placed in a 1-liter four-necked flask and cooled to -5 ° C. Next, 34.2 g of methyldichlorosilane was added to the flask, and ammonia was further blown for 2 hours while stirring to obtain a liquid containing a reaction product. After removing the precipitate contained in this solution by filtration, the filtrate was depressurized to remove methylene chloride from the filtrate, thereby obtaining resinous polysilazane B.

Table 1 shows the results of elemental analysis of the above polysilazanes A and B, the Si / N ratio, and the weight average molecular weight. In addition, these weight average molecular weights are polystyrene conversion values measured by gel chromatography.

[0065]

Example 1 A 10 wt% xylene solution of polysilazane A and linoleic acid were mixed so that the molar ratio of polysilazane A / linoleic acid was 1/1, and the mixture was reacted at a temperature of 80 ° C. for 2 hours. Then, the solvent was removed under reduced pressure to obtain a resinous modified polysilazane. Table 1 shows the elemental analysis results, Si / N ratio and weight average molecular weight of the obtained modified polysilazane. The weight average molecular weight of the obtained modified polysilazane was measured in the same manner as the weight average molecular weight of the above polysilazanes A and B.

The modified polysilazane obtained as described above was dissolved in xylene to obtain a coating solution for forming a silica-based film having a solid content of 20% by weight. This coating solution is applied on a 4-inch silicon wafer by a spin coating method, and the obtained coating film is dried by heating at 150 ° C. for 2 minutes, and then baked at 350 ° C. for 1 hour in the air to form a silica coating. Was formed. Table 2 shows the results of ESCA analysis of the formed silica-based film and the results of measurement of crack resistance, denseness, and alkali resistance. The crack resistance, denseness and alkali resistance were measured as follows. a) Crack resistance A 2 μm silica-based coating was formed, and the presence or absence of cracks in this silica-based coating was observed with a microscope. b) Denseness Mixed solution of HF and HNO ₃ (HF / HNO ₃ = 1/1)
(00 weight ratio) was calculated from the change in film thickness before and after the silica-based coating formed as described above was immersed in the etching solution for 2 minutes. In addition, it is evaluated that the smaller the amount of change in film thickness per unit time, the better the denseness. c) Alkali resistance Calculated from the change in film thickness before and after the silica-based coating formed as described above was immersed in a 5% by weight NaOH aqueous solution at 40 ° C. for 20 minutes. It should be noted that the smaller the amount of change in film thickness is,
It is evaluated as having excellent alkali resistance.

[0067]

Example 2 A 5% by weight solution of polysilazane A in methyl isobutyl ketone and oleic acid were mixed so that the molar ratio of polysilazane A / oleic acid was 9/1.
This mixed solution was heated at 80 ° C. for 5 hours to obtain polysilazane A.
And oleic acid, and then the solvent in the liquid was removed under reduced pressure to obtain a resinous modified polysilazane. As a result of elemental analysis of the obtained modified polysilazane, Si /
Table 1 shows the N ratio and the weight average molecular weight. The weight average molecular weight of the obtained modified polysilazane was measured in the same manner as the weight average molecular weight of the above polysilazanes A and B.

Using the modified polysilazane thus obtained, a coating liquid for forming a silica-based film and a silica-based coating were obtained in the same manner as in Example 1, and the silica-based coating obtained in the same manner as in Example 1 Was subjected to ESCA analysis, and crack resistance, denseness, and alkali resistance were measured.

Table 2 shows the results of the above analysis and measurement.

[0070]

Example 3 A 3% by weight butyl ether solution of polysilazane B and dimethyl maleate were mixed so that the molar ratio of polysilazane B / dimethyl maleate was 96/4, and the mixture was reacted at a temperature of 50 ° C. for 2 hours. Thus, a resinous modified polysilazane was obtained. Table 1 shows the elemental analysis results, Si / N ratio and weight average molecular weight of the obtained modified polysilazane. The weight average molecular weight of the obtained modified polysilazane was measured in the same manner as the weight average molecular weight of the above polysilazanes A and B.

Using the modified polysilazane thus obtained, a coating solution for forming a silica-based coating and a silica-based coating were obtained in the same manner as in Example 1, and the silica-based coating obtained in the same manner as in Example 1 Was subjected to ESCA analysis, and crack resistance, denseness, and alkali resistance were measured.

Table 2 shows the results of the above analysis and measurement.

[0073]

Comparative Example 1 A silica-based coating was obtained in the same manner as in Example 1 by using a 20 wt% xylene solution of polysilazane A as a coating solution for forming a silica-based coating. Was subjected to ESCA analysis, and crack resistance, denseness, and alkali resistance were measured.

Table 2 shows the results of the above analysis and measurement.

[0075]

[Table 1]

[0076]

[Table 2]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-345826 (JP, A) JP-A-5-105486 (JP, A) JP-A-1-203476 (JP, A) JP-A-1- 138107 (JP, A) JP-A-62-88327 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 1/00-201/10

Claims (2)

(57) [Claims] 1. A film forming component represented by the following general formula [I]: (Wherein R ₁ , R ₂ and R ₃ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.) One or more polysilazanes having at least a repeating unit represented by the formula: And the following general formula [II] RCOOR '... [II] (wherein, R is a hydrocarbon group having 1 to 30 carbon atoms, and R' is a hydrogen atom or a hydrocarbon having 1 to 20 carbon atoms. A carboxylic acid and / or a carboxylic acid ester represented by the formula: Si / N
A coating liquid for forming a silica-based film, comprising a modified polysilazane having an atomic ratio in a range of 1.07 to 1.30 . 2. A coated substrate comprising a silica-based coating formed by using the coating solution according to claim 1.