JP2890893B2 - Silica-based coating liquid - 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 formed between a passivation film of a semiconductor device and a sealing resin to form cracks in the passivation film and sealing resin. The present invention relates to a coating liquid for forming a silica-based film, which is preferably used as a coating liquid for forming a buffer coat for preventing separation between the substrate and an IC chip. In addition, the present invention is a semiconductor, the diffusion prevention of impurities such as liquid crystal display element, insulation, surface flattening, etc.
The present invention also relates to a silica-based coating liquid for forming a thick film, particularly for protecting a solid surface of silicon, glass, ceramics, metal, or the like.

[0002]

2. Description of the Related Art A coating solution obtained by hydrolyzing and condensing an alkoxysilane is disclosed in JP-B-63-8186.
No. JP-A-58-204815, JP-B-63-460.
As disclosed in, for example, Japanese Patent Application Laid-Open No. 95, it is conventionally known, and is used for the purpose of preventing diffusion of impurities in a semiconductor element, insulating, and flattening unevenness.

On the other hand, conventionally, aromatic polyimide has been used as a surface protective film of a semiconductor element, but it cannot be used as a surface protective film of an ultraviolet-erasable ROM due to low ultraviolet light transmittance. There is.

[0004] Therefore, as a coating solution for forming a silica-based film, which has good ultraviolet light transmittance and is capable of forming a thick film,
The present inventors have proposed to introduce a phenyl group in an alkoxysilane in a specific range amount (Japanese Patent Application No. 2-205).
880).

[0005] However, in this conventional method, there is a problem that the coatability is lowered because the polymer concentration is increased for forming a thick film, and unevenness and streaks are generated in the film.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art. It is an object of the present invention to form a thick film and have excellent coatability. An object of the present invention is to provide a coating solution for forming a silica-based film.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by the following configuration.

A coating liquid for forming a silica-based film obtained by hydrolyzing and condensing an alkoxysilane, wherein the coating liquid is an alcohol R'O produced by hydrolysis.
H is obtained by hydrolyzing and condensing an alkoxysilane represented by the general formula (1) having a boiling point of 80 ° C. or more in a solvent 0.5 times or less the weight of the alkoxysilane. Coating solution for forming a silica-based film.

R ₁ Si (OR ′) _m (OR ″) _n (1) (where R is at least one selected from the group consisting of hydrogen, an alkyl group, an alkenyl group, and an aryl group;
R 'is at least one member selected from the group consisting of an alkyl group, an alkoxyalkyl group and an aryl group, and R "is at least one member selected from the group consisting of hydrogen, an alkyl group, an alkoxyalkyl group and an aryl group. l is 1 or 2, m is an integer of 1 to 3, n is an integer of 0 to 2, l
+ M + n = 4. ) The alkoxysilane represented by the general formula (1) is hydrolyzed to produce an alcohol R'OH as shown below. In the present invention, the alkoxysilane represented by the alcohol R'OH produced by hydrolysis is used as the alkoxysilane. It is important to select an alkoxysilane having a boiling point of 80 ° C. or higher.

R _l Si (OR ′) _m (OR ″) _n + (m + n) H ₂ O → R _l Si (OH) _m (OH) _n + mR′OH + nR ″ OH Conventionally, this is used for this purpose. As the alkoxysilane, those which produce a low-boiling alcohol having a boiling point of less than 80 ° C such as methanol and ethanol by hydrolysis have been used, but this produces an alcohol having a boiling point of 80 ° C or more, that is, an alcohol having a high boiling point. This is because when alkoxysilane is used, it is considered to deteriorate crack resistance because it is an alkoxysilane having an alkoxy group having a large number of carbon atoms. For example, Tokiko Sho 6
As disclosed in Japanese Patent Application Laid-Open No. 3-46095, a coating liquid using an alkoxysilane having an alkoxy group having a large number of carbon atoms has a bulky shrinkage due to elimination of a residual alkoxy group during firing. And cracks were generated in the film.

However, based on such conventional knowledge, the present inventors increased the amount of the alkoxysilane to be added so as to increase the polymer concentration for forming a thick film. A film obtained by spinner-coating a coating solution using an alkoxysilane to be used has irregularities and streaks, and has encountered a situation where it is very difficult to obtain a uniform film. This is not a problem because a small amount of low boiling alcohol is generated in the coating liquid for forming a thin film, but a large amount of alkoxysilane is charged in a coating liquid for forming a thick film, and a low boiling point is inevitably generated. This is because the boiling alcohol becomes large. That is, when spinner coating the coating liquid, the coating liquid containing a lot of low-boiling substances quickly evaporates the low-boiling alcohol during spinner rotation, the polymer concentration of the dripping liquid changes rapidly,
It was found that unevenness, streaks, and the like occurred in the obtained film.

Therefore, the present invention is based on the finding that alkoxysilanes that generate low-boiling alcohols are unsuitable for coating liquids for forming thick films, but rather alkoxysilanes that generate high-boiling alcohols are suitable. It is.

Further, the coating liquid of the present invention is obtained by hydrolyzing an alkoxysilane having a boiling point of 80 ° C. or higher of the alcohol formed by the hydrolysis in a solvent 0.5 times or less the weight of the alkoxysilane. It is important to form by condensing, whereby a coating liquid for forming a silica-based film, which can form a thick film and has excellent coatability, can be obtained.

Next, in the general formula (1), R is hydrogen,
It is an alkyl group, an alkenyl group, or an aryl group.
Specific examples include hydrogen, methyl, ethyl, propyl, butyl, vinyl, phenyl, tolyl, biphenylyl, and naphthyl groups. If a relatively thin film is to be formed, a conventionally used alkyl group such as a methyl group may be used, but from the viewpoint of forming a thick film as described above, And a phenyl group is preferred.

In the general formula (1), R 'is an alkyl group, an alkoxyalkyl group or an aryl group. As described above, specific OR's at which the boiling point of R'OH is 80 ° C. or higher include propoxy, butoxy, 2-methoxyethoxy, 2-ethoxyethoxy, and 2-propoxyethoxy. , 2-butoxyethoxy group, 1-methyl-2-methoxyethoxy group, 1-methyl-2-butoxyethoxy group, phenoxy group and the like. May be combined.

In the general formula (1), R ″ is hydrogen, an alkyl group, an alkoxyalkyl group or an aryl group. Specific OR ″ includes not only the above OR ′ but also a hydroxy group Methoxy group, ethoxy group and the like.

In the general formula (1), 1 is 1 or 2, and 1 is preferable from the viewpoint of the adhesion of the obtained film. Also,
m is an integer of 1 to 3; n is an integer of 0 to 2;
n = 4. m is preferably as large as possible from the viewpoint of coatability, and is preferably 3.

Specific examples of the alkoxysilane represented by the general formula (1) include methyltripropoxysilane, methyltributoxysilane, methyltris (2-methoxyethoxy) silane, dimethyldipropoxysilane, phenyltris (2-methoxy Examples thereof include ethoxy) silane, and phenyltris (2-methoxyethoxy) silane is preferable from the viewpoint of forming a thick film. These alkoxysilanes may be used alone or in combination of two or more. Actually, it is better to use a mixture of two or more kinds of alkoxysilanes than to use a single alkoxysilane in order to make both the crack resistance and the ultraviolet light transmittance compatible.

Here, to satisfy both the crack resistance and the ultraviolet light transmission means, specifically, 25 mm / 2.0 μm in thickness.
This means that a film having a transmittance at 4 nm of at least 50% or more and having a crack-free thickness of 1.5 μm or more can be formed. For this purpose, methylalkoxysilane and phenylalkoxysilane are mixed. It is preferred that the total number of methyl groups in the alkoxysilane be at least twice and at most 30 times the total number of phenyl groups. When two or more alkoxysilanes are mixed, not only alkoxysilanes that generate high-boiling alcohols but also alkoxysilanes that generate low-boiling alcohols may be added within a range that does not impair the object of the present invention. .

The solvent used in the present invention is preferably an organic solvent, for example, alkyl alcohols such as methanol, ethanol, propanol and butanol; ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, ethylene glycol monoethyl ether, propylene glycol Alkylene glycols such as monomethyl ether and propylene glycol monobutyl ether; ethers such as tetrahydrofuran, petroleum ether and diethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone; N-methyl-2-pyrrolidone and dimethylacetamide And amides such as dimethylformamide. These may be used alone or as a mixture of two or more. However, from the viewpoint of coatability, it is preferable to select from those having a high boiling point. In order to form a thick film, an amide solvent having an effect of improving crack resistance is preferable. -Pyrrolidone is preferred.

It is important that the amount of the solvent used is not more than 0.5 times by weight based on the alkoxysilane.
When the solvent is used in an amount of more than 0.5 times, the concentration of the silicon polymer generated by the reaction becomes low, so that it is not used for forming a thick film. Preferably, the weight ratio to the alkoxysilane is 0.3 times or less, more preferably, 0.1 times.
It is better to make it twice or less. However, if the ratio is less than 0.1 times, the reaction proceeds rapidly, thereby deteriorating the order of the obtained polymer structure and causing deterioration in film physical properties and storage stability.

The amount of water to be added for the hydrolysis reaction is not particularly limited, but for forming a thick film,
It is preferably selected in the range of 0.5 to 5.0 times the molar amount of the alkoxysilane, more preferably 1.0 to 3.0.
It is preferable to use it in the range of 0 times the molar amount.

A catalyst can be added to the system to promote the reaction. Examples of the catalyst include hydrochloric acid, phosphoric acid, phosphoric acid ester, sulfuric acid, benzenesulfonic acid, p-toluenesulfonic acid, methylsulfonic acid, boric acid, acetic acid, oxalic acid, oxides such as Al and Zn, amberlite ( Solid catalysts such as Organo Corporation and Nafion (DuPont) can be used.

The reaction temperature is usually selected from the range from the freezing point to the boiling point of the reaction system, but it is of course possible to carry out the reaction at a temperature higher than the boiling point under pressure.

The mode of the reaction may be either a continuous type or a batch type. After the reaction, if necessary, a solvent may be added or removed to adjust the viscosity, and a viscosity modifier such as hydroxypropylcellulose or glycerin may be added.

[0026]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 188 g of methyltris (2-methoxyethoxy) silane was added to a mixture of 70 g of butanol, 40 g of water and 5 g of sulfuric acid.
(0.7 mol) and 33 g (0.1 mol) of phenyltris (2-methoxyethoxy) silane were added while stirring the mixture. Next, the solution was heated at 50 ° C. for 3 hours and aged. The alcohol produced in the resulting solution is 2-
It was methoxyethanol and its boiling point was 124 ° C. Using this solution as a coating solution, a silicon wafer was coated using a spinner at 1500 rpm for 15 seconds.
Dry at 80 ° C for 30 minutes in nitrogen, and further at 300 ° C for 3 minutes.
It was baked for 0 minutes to obtain a silica-based coating.

No defects such as unevenness and streaks were observed in the obtained film, and microscopic observation revealed no crack. Also,
The film thickness was 2.1 μm.

Comparative Example 1 Methyltriethoxysilane 1 was used as the starting alkoxysilane.
Example 1 except that a mixture of 25 g (0.7 mol) and 24 g (0.1 mol) of phenyltriethoxysilane was used.
The solution was prepared in the same manner as described above. The alcohol formed in the resulting solution was ethanol, and the boiling point was 78 ° C. The resulting solution was applied as a coating solution on a silicon wafer using a spinner at 1500 rpm for 15 seconds, dried in nitrogen at 80 ° C. for 30 minutes, and further baked at 300 ° C. for 30 minutes to obtain a silica-based solution. A coating was obtained.

The obtained film had many defects such as unevenness and streaks, and was not practical.

Example 2 50 g of propylene glycol monobutyl ether and 6 parts of water
To a mixture of 0 g and 3 g of acetic acid, a mixture of 220 g (1.0 mol) of methyltriisopropoxysilane and 24 g (0.1 mol) of phenyltriethoxysilane was added with stirring. Next, heat the solution at 50 ° C. for 3 hours,
Aged. The resulting solution was applied as a coating solution on a silicon wafer using a spinner at 1500 rpm for 15 seconds, dried in nitrogen at 80 ° C. for 30 minutes, and further baked at 300 ° C. for 30 minutes to obtain a silica-based coating. Was.

No defects such as unevenness and streaks were observed in the obtained film, and as a result of microscopic observation, no crack was found. Also,
The thickness was 3.5 μm.

Comparative Example 2 The solvent was propylene glycol monobutyl ether 150
A solution was prepared in the same manner as in Example 2 except that the amount was changed to g.
The obtained solution was coated as a coating solution on a silicon wafer at 1500 rpm for 15 seconds using a spinner,
Dry at 80 ° C for 30 minutes in nitrogen, and further at 300 ° C for 3 minutes.
It was baked for 0 minutes to obtain a silica-based coating.

The obtained film was as thin as 1.0 μm.

Example 3 50 g of tetrahydrofuran and 10 parts of dimethylacetamide
In a mixture of 0 g, 100 g of water and 5 g of Nafion, 440 g (2.0 mol) of methyltripropoxysilane, 74 g (0.5 mol) of dimethyldiethoxysilane, 27 g (0.1 mol) of diphenyldiethoxysilane and 113 g of phenyltripropoxysilane ( 0.4 mol) of the mixture was added with stirring. The obtained solution was used as a coating liquid on a silicon wafer using a spinner at 1500 r.
pm, 15 seconds, 80 ° C in nitrogen for 30 seconds.
After drying for 300 minutes, it was further baked at 300 ° C. for 30 minutes to obtain a silica-based coating.

No defects such as unevenness and streaks were observed in the obtained film, and as a result of microscopic observation, no crack was found. Also,
The film thickness was 3.0 μm.

EXAMPLE 4 18 g of methyltriethoxysilane was added to a mixture of 10 g of N-methyl-2-pyrrolidone, 15 g of water and 1 g of phosphoric acid.
(0.10 mol), methyltris (2-methoxyethoxy) silane 27 g (0.10 mol) and phenyltris (2-methoxyethoxy) silane 17 g (0.05 m)
ol) was added with stirring. The obtained solution was applied as a coating solution on a silicon wafer using a spinner at 1500 rpm for 15 seconds, and the coating was performed in nitrogen for 8 hours.
It was dried at 0 ° C. for 30 minutes and further baked at 300 ° C. for 30 minutes to obtain a silica-based coating.

No defects such as unevenness and streaks were observed in the obtained film, and as a result of microscopic observation, no crack was found. Also,
The thickness was 2.0 μm.

Example 5 Methyl tris (2-methoxyethoxysilane) was added to a mixture of 100 g of diisobutyl ketone, 20 g of water and 3 g of hydrochloric acid.
268 g (1.0 mol) and tetraethoxysilane 72
g (0.5 mol) and 12 g of dimethyldimethoxysilane
(0.1 mol) and 48 g of phenyltriethoxysilane
(0.2 mol) of the mixture was added with stirring.
The obtained solution was coated as a coating solution on a silicon wafer at 1500 rpm for 15 seconds using a spinner,
Dry at 80 ° C for 30 minutes in nitrogen, and further at 300 ° C for 3 minutes.
It was baked for 0 minutes to obtain a silica-based coating.

No defects such as unevenness and streaks were observed in the obtained film, and as a result of microscopic observation, no crack was found. Also,
The film thickness was 2.2 μm.

[0041]

The coating solution for forming a silica film according to the present invention is excellent in coatability and does not cause defects such as unevenness and streaks in the coated film. In addition, the film after firing is particularly 2.0 μm
Even when formed in the above film thickness, since there is no crack and excellent ultraviolet light transmittance, it can be used as a buffer coat for an ultraviolet erasing ROM instead of an aromatic polyimide.

Claims (3)

(57) [Claims] 1. A coating solution for forming a silica-based film obtained by hydrolyzing and condensing an alkoxysilane, wherein the coating solution is formed by alcohol R'O produced by hydrolysis.
H is obtained by hydrolyzing and condensing an alkoxysilane represented by the general formula (1) having a boiling point of 80 ° C. or more in a solvent 0.5 times or less the weight of the alkoxysilane. Coating solution for forming a silica-based film. R ₁ Si (OR ′) _m (OR ″) _n (1) (where R is at least one selected from the group consisting of hydrogen, an alkyl group, an alkenyl group, and an aryl group;
R 'is at least one member selected from the group consisting of an alkyl group, an alkoxyalkyl group and an aryl group, and R "is at least one member selected from the group consisting of hydrogen, an alkyl group, an alkoxyalkyl group and an aryl group. l is 1 or 2, m is an integer of 1 to 3, n is an integer of 0 to 2, l
+ M + n = 4. ) 2. The coating liquid for forming a silica-based film according to claim 1, wherein R of the alkoxysilane represented by the general formula (1) is a phenyl group. 3. The method of claim 1, wherein the alkoxysilane is phenyltris (2-
2. The coating liquid for forming a silica-based film according to claim 1, wherein the coating liquid is methoxyethoxy) silane.