JP2015180739A - Production method of silicone polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel silicone polymer that can be formed into a film at a temperature of 500°C or higher and give a film having characteristics of high transparency and crack resistance.SOLUTION: A production method of a silicone polymer is provided, in which 4-methoxybenzyl trimethoxysilane is hydrolyzed in a mixture solvent of an aprotic solvent and an alcohol solvent or a mixture solvent of a ketone solvent and an alcohol solvent in the presence of a basic catalyst, and further subjected to condensation polymerization to produce a silicone polymer having a structural unit represented by the formula below. In the production method, the basic catalyst is tetrabutylammonium hydroxide, tetraethylammonium hydroxide, or tetramethylammonium hydroxide.

Description

  The present invention relates to a method for producing a silicone polymer useful as a heat resistant material for electronic parts such as liquid crystal display elements and semiconductor elements.

  In recent years, as electronic materials used for electronic components such as liquid crystal display elements and semiconductor elements, high transparency that is highly transmissive with visible light, heat resistance and resistance to withstand various processing steps when manufacturing elements. There is an increasing need for resins that have properties such as chemical properties and crack resistance.

  Among them, a silicone material having a phenol group that is soluble in an alkaline solvent has attracted attention as a material used in microfabrication. Hydroxybenzylsilsesquioxane, which is an alkali-soluble silicone material, is used as a two-layer resist method, for example, and can form a high aspect ratio pattern on a stepped substrate (Patent Document 1).

  A synthesis example of a silicone polymer containing an alkoxy group in which a phenol group, which is a precursor of a silicone material having a phenol group, is protected with an alkyl group such as a methyl group or an ethyl group is simply made with water using chlorosilane as a raw material. It is synthesized by hydrolysis, and there are many examples where hydrolysis is performed under acidic conditions using hydrochloric acid generated by the reaction of chlorosilane with water as a catalyst. However, the silicone polymer synthesized under acidic conditions of chlorosilane becomes a material with a large amount of silanol remaining at the end. For example, in a dealkylation reaction for synthesizing a silicone polymer having a phenol group, a dealkylation reaction occurs when a large number of silanol groups remain. Therefore, there is a disadvantage that dealkylation reaction must be performed after protecting the terminal silanol group (Patent Documents 1 to 5).

  On the other hand, for example, a wiring used as a conductive portion of a semiconductor generates a high heat due to an increase in flowing current due to recent high functionality and high density. Therefore, the insulating film used in the process is required to be more heat resistant, and a high heat resistant material capable of forming a film at 500 ° C. or higher is required. Among them, silicone resins having a silsesquioxane skeleton are particularly excellent in heat resistance, and have been widely used by utilizing these characteristics.

  In the heat-resistant film formed of this silicone resin, the flatness of the film surface is important, and there is a demand for a film that does not crack on the film surface after film formation by heating. For example, in a multilayer wiring process of LSI manufacturing, if a film formed by heating has cracks, when a film is formed on it, a newly formed film is not uniform and a nonuniform film is formed. There is a possibility that. When the film thus formed is exposed to light, irregular reflection or scattering of light occurs near the non-uniform film interface, and a uniform pattern cannot be formed. Thus, since cracks on the film surface often affect film characteristics such as optical characteristics and mechanical characteristics, a film that does not normally crack is required.

For example, the crack resistance of a cured film obtained by dissolving a general silicone composition synthesized with a phenyl group or methyl group in a solvent and heating and curing at 400 ° C. is evaluated. Therefore, it is difficult to adapt the process to be used at a high temperature of 500 ° C. or higher. (Patent Document 6)
From the above, there has been a demand for a silicone material that can be formed at a temperature of 500 ° C. or higher, has high transparency, and does not crack in the obtained film.

JP-A-9-87391 JP-A-8-334900 JP-A-8-334901 JP-A-9-274319 JP 2002-338690 A JP 2007-238848 A

  The present invention has been made for the purpose of providing a novel silicone polymer capable of forming a film having high transparency and crack resistance.

  The present invention has the following formula:

Is hydrolyzed in the presence of a basic catalyst in a mixture of an aprotic solvent and an alcohol solvent or in a mixture of a ketone solvent and an alcohol solvent, followed by a condensation polymerization reaction. The following formula

A silicone polymer production method for producing a silicone polymer having a structural unit represented by formula (1), wherein the basic catalyst is tetrabutylammonium hydroxide, tetraethylammonium hydroxide, or tetramethylammonium hydroxide. It is a manufacturing method of coalescence.

  The silicone polymer of the present invention is spin-coated on a substrate such as a silicon wafer, and is in close contact with the substrate even when heated at 500 ° C. or higher, has high transparency and high crack resistance, and is an insulating material for electronic materials. It is an excellent material for films and protective films.

  In addition, the silicone copolymer of the present invention is a material having good transparency in the visible light wavelength, excellent adhesion and crack resistance, and high cracking even after firing electronic parts such as liquid crystal display elements and semiconductor elements. Since it has resistance, it can be used as a highly heat-resistant material such as an electronic device or a solar battery.

  Further, the silicone copolymer of the present invention can be applied not only to the electronic field but also to a wide range of fields such as paints and adhesives.

1 shows an IR chart of the compound of Example 1. The IR chart of the compound of the comparative example 1 is shown.

  The present invention has the following formula:

Is hydrolyzed in the presence of a basic catalyst in a mixture of an aprotic solvent and an alcohol solvent or in a mixture of a ketone solvent and an alcohol solvent, followed by a condensation polymerization reaction. The following formula

A silicone polymer production method for producing a silicone polymer having a structural unit represented by formula (1), wherein the basic catalyst is tetrabutylammonium hydroxide, tetraethylammonium hydroxide, or tetramethylammonium hydroxide. It is a manufacturing method of coalescence.

  In the present invention, the following structure of the silicone polymer

Represents a silsesquioxane skeleton, wherein each silicon atom is bonded to three oxygen atoms, and each oxygen atom is bonded to two silicon atoms. The silsesquioxane skeleton has, for example, the following general formula

It can be shown by the structural formula shown in

  The present invention has the following formula:

Is hydrolyzed in the presence of a basic catalyst, followed by a condensation polymerization reaction.

By using the silicon compound represented by the formula (1), a silicone polymer having a low molecular weight and capable of being purified by distillation and having a high purity can be obtained.

  In this invention, when a basic catalyst is used, there are few terminal silanol groups of a cured film.

  The basic catalyst is tetrabutylammonium hydroxide, tetraethylammonium hydroxide, or tetramethylammonium hydroxide. Furthermore, tetramethylammonium hydroxide capable of controlling the hydrolysis rate of the monomer with a strong base is preferable.

  0.001-1.0 equivalent is preferable with respect to the number-of-moles of a raw material monomer, and, as for the usage-amount of a basic catalyst, 0.01-0.5 equivalent is more preferable.

  The reaction temperature of the hydrolysis reaction and polycondensation reaction is preferably 0 to 100 ° C., and more preferably 20 to 50 ° C. because the reaction easily proceeds by using a catalyst.

  In the present invention, a silicon compound is hydrolyzed in a solvent in which an aprotic solvent and an alcohol solvent are mixed or in a solvent in which a ketone solvent and an alcohol solvent are mixed in the presence of a basic catalyst, and further a condensation polymerization reaction is performed. To do.

  The aprotic solvent is preferably toluene or xylene. The ketone solvent is preferably methyl ethyl ketone or methyl isobutyl ketone.

  The alcohol solvent is preferably methanol, ethanol, or 2-propanol.

  Considering the solvent cost and the purification method of the obtained copolymer, toluene, methyl isobutyl ketone, and 2-propanol are particularly preferable.

  The obtained siloxane resin can be dissolved in a high-boiling solvent such as propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, ethyl lactate, and applied to a silicon wafer or a glass substrate. High boiling solvents such as propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, and ethyl lactate can be used as reaction solvents for hydrolysis and polycondensation reactions.

  After completion of the hydrolysis reaction and polycondensation reaction, a nonpolar solvent is added to separate the reaction product and water, and the reaction product dissolved in the organic solvent is recovered. After washing with water, the solvent is retained. The desired product can be obtained by leaving.

  In this way, the silicone copolymer of the present invention can be synthesized.

  Hereinafter, the present invention will be specifically described with reference to examples.

  In the following examples, the following apparatus was used for the measurement, and general reagents purchased from reagent manufacturers (Tokyo Chemicals, Wako Pure Chemicals, Nacalai Tesque, Azmax, Shin-Etsu Chemical) were used as raw materials.

Measuring device NMR measurement: Measured with a 400 MHz NMR measuring instrument manufactured by JEOL.

  IR measurement: IR Prestige-21 manufactured by Shimadzu. In the case of a solution, a small amount of a synthetic product was applied to a KBr plate and sandwiched between different KBr plates to transmit infrared light.

  GPC measurement: HLC-8220 manufactured by Tosoh Corporation. Tosoh TSK-gel Super3000, TSK-gel Super2000, and TSK-gel Super1000 were used, and two TSK-gel SuperH-RCs were used as references. The solvent was THF, the column flow rate was 0.35 mL / min, the column temperature was 40 ° C., and the measurement was performed by RI. The molecular weight distribution was calculated using polystyrene (a standard sample manufactured by Tosoh Corp.) as the standard for the molecular weight distribution.

  GC measurement: Measured with GC-2010 series manufactured by Shimadzu using capillary column DB-5 manufactured by J & W.

Synthesis example 1
Synthesis example of 4-methoxybenzyltrimethoxysilane To a 500 mL four-necked flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer, 19.0 g (0.784 mol) of magnesium and 300 mL of tetrahydrofuran were added, and the iodine side was adjusted. added. A small amount of 4-methoxybenzyl chloride was added dropwise thereto to start the reaction, and then a total of 116.9 g (0.746 mol) of 4-methoxybenzyl chloride was added dropwise at 5 to 10 ° C. to prepare a Grignard reagent.

  Next, 568 g (3.73 mol) of normal methyl silicate was charged into a 1000 mL four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer, and 2 Grignard reagents previously adjusted at a temperature of 70 to 80 ° C. It was added dropwise over time. After cooling and filtering the precipitated magnesium salt, the solvent was distilled off, and 122 g (0.495 mol) of a 128-135 ° C. fraction was recovered at a reduced pressure of 5 mmHg. As a result of GC analysis of the obtained fraction, GC purity was 98.8%, and NMR and IR analysis revealed that it was 4-methoxybenzyltrimethoxysilane.

  The spectrum data of the obtained compound is shown below.

Infrared absorption spectrum (IR) data
2839,2941cm ^-1 (-CH3, Ar), 1080cm ^-1 (Si-O)
Nuclear magnetic resonance spectrum (NMR) data (1H-NMR solvent: CDCl ₃ )
_{2.15ppm (s, 2H, -CH 2} -), 3.52ppm (s, 9H, -OCH3), 3.76ppm (s, 3H, CH 3 -O -), 6.78-6.80ppm (d, J = 8.5Hz, 2H, Ar-H), 7.07-7.09 ppm (d, J = 8.5 Hz, 2H, Ar-H).

Example 1
Synthesis of 4-methoxybenzylsilsesquioxane

  A 500 mL four-necked flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer was charged with 2.6 g of 25% tetramethylammonium hydroxide aqueous solution and 9.4 g of water, and 60 mL of 2-propanol and 30 mL of toluene were added. It was. Thereto, a 30 mL solution of 4-methoxybenzyltrimethoxysilane in 59.2 g (0.244 mol) in toluene was placed in a dropping funnel and added dropwise at a temperature of 35 to 45 ° C. with stirring. After completion of the dropwise addition, the mixture was aged for 2 hours, cooled to room temperature, and extracted with 90 mL of toluene and 90 mL of water. After putting into the separatory funnel and discharging the aqueous layer, it was washed with dilute acetic acid aqueous solution, and after discharging the aqueous layer, it was washed with water four times. Thereafter, the oil layer was filtered with a 0.5 μm PTFE filter, and then toluene was distilled off to obtain 46.8 g of 4-methoxybenzylsilsesquioxane.

  The spectrum data of the obtained copolymer is shown below.

Infrared absorption spectrum (IR) data
1038-1296cm ^-1 (Si-O), 2833-3030cm ^-1 (CH), 3410 cm ^-1 (Si-OH)
Nuclear magnetic resonance spectrum (NMR) data (1H-NMR δ (ppm), solvent: CDCl ₃ )
1.78 (bs, 2H, -CH _2- ), 3.68 (bs, 3H, CH ₃ -O-), 6.72 (bs, 4H, Ar-H)
GPC analysis data: Mw = 2,320, Mn = 2,050, Mw / Mn = 1.13 (polystyrene conversion).

Comparative Example 1
Synthesis of 4-methoxybenzylsilsesquioxane polymer

  A 500 mL four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer was charged with 3.3 g of 35% aqueous hydrochloric acid and 120 g of water, and stirring was started. Moreover, the toluene 120mL solution of 4-methoxybenzyltrimethoxysilane 78.5g (0.324 mol) was dripped at 15-20 degreeC. Thereafter, the mixture was aged for 2 hours at a temperature of 15 to 20 ° C., extracted by adding toluene, removed the aqueous layer, washed 4 times with an aqueous sodium hydrogen carbonate solution, dilute acetic acid aqueous solution and water, concentrated the oil layer to 4- 57.5 g of a methoxybenzylsilsesquioxane condensation polymer was obtained.

  The spectrum data of the obtained copolymer is shown below.

Infrared absorption spectrum (IR) data
1036-1246cm ^-1 (Si-O), 2951-3071cm ^-1 (CH), 3165-3603cm ^-1 (Si-OH)
Nuclear magnetic resonance spectrum (NMR) data (1H-NMR δ (ppm), solvent: CDCl ₃ )
_{1.83 (bs, 2H, -CH 2} -), 3.68 (bs, 3H, CH 3 -O -), 6.69 (bs, 4H, Ar-H)
GPC analysis data: Mw = 2,530, Mn = 1,610, Mw / Mn = 1.57 (polystyrene conversion).

Comparative Example 2
Synthesis of phenylsilsesquioxane / methylsilsesquioxane copolymer

(Indicates a charged molar composition ratio of 70:30)
(50:50 in the structural formula is the molar ratio of the raw materials used)
A 500 mL four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer was charged with 50.6 g of toluene and 33.4 g of water, and 3.13 g (0.03 mol) of 35% hydrochloric acid was added. . Next, a solution of 45.3 g (0.211 mol) of phenyltrimethoxysilane and 25.3 g of toluene of 12.5 g (0.091 mol) of methyltrimethoxysilane was added dropwise at 15 to 20 ° C. After completion of dropping, the mixture was aged at the same temperature for 2 hours. As a result of analyzing the reaction solution at this time by GC, it was found that no raw material remained. Next, toluene and water were added for extraction, and after washing with an aqueous sodium hydrogen carbonate solution, the solution was washed with water until the solution became neutral. The toluene oil layer was recovered, and toluene was removed to obtain 27.2 g of the target white solid compound.

  The spectrum data of the obtained copolymer is shown below.

Infrared absorption spectrum (IR) data
1028-1132cm ^-1 (Si-O), 2970-3070cm ^-1 (CH), 3070-3700cm ^-1 (Si-OH)
Nuclear magnetic resonance spectrum (NMR) data (1H-NMR δ (ppm), solvent: CDCl ₃ )
0.16 (bs), 7.00-7.57 (m), 7.57-7.90 (m)
GPC analysis data: Mw = 960, Mw / Mn = 1.25 (polystyrene conversion).

<Evaluation of synthetic materials>
The IR measurement of Example 1 and Comparative Examples 1 and 2 was performed. In addition, each of the produced silicone polymers was dissolved in propylene glycol monomethyl ether acetate to obtain a solution in which the solid content concentration was adjusted to 40% by weight. Thereafter, the solution is filtered through a PTFE (polytetrafluoroethylene) filter, and spin-coated for 30 seconds on a silicon wafer or glass substrate at a rotational speed such that the film thickness after removal of the solvent is 2.0 μm. . Thereafter, the solvent was removed over 100 ° C./30 seconds, and the film was finally baked in an electric furnace over 750 ° C./1 hour to obtain an insulating film.

[Judgment of silanol group size]
As a result of each IR measurement, a large absorption near 3500 cm ⁻¹ was regarded as having a large amount of silanol, and a small absorption was regarded as having a low silanol.

[Heat-cured film properties]
The film thickness on the silicon wafer was measured with respect to the film formed by the above film forming method, and the presence or absence of cracks was confirmed.

<Evaluation results>
The evaluation results of the cured film and the overall evaluation based thereon are shown in Table 1 below.

  As described above, the silicone polymer synthesized under basic conditions has a small amount of silanol by IR measurement, and a cured film formed by heating at 500 ° C. or higher is free from cracks and can form an excellent heating film. it can. Therefore, the silicone copolymer of the present invention can be applied not only in the field of electronic materials but also in a wide range of fields such as paints and adhesives.

Claims (4)

Following formula

Is hydrolyzed in the presence of a basic catalyst in a mixture of an aprotic solvent and an alcohol solvent or in a mixture of a ketone solvent and an alcohol solvent, followed by a condensation polymerization reaction. The following formula

A silicone polymer production method for producing a silicone polymer having a structural unit represented by formula (1), wherein the basic catalyst is tetrabutylammonium hydroxide, tetraethylammonium hydroxide, or tetramethylammonium hydroxide. Manufacturing method of coalescence. 2. The method for producing a silicone polymer according to claim 1, wherein the basic catalyst is tetramethylammonium hydroxide. 3. The method for producing a silicone polymer according to claim 1, wherein the aprotic solvent is toluene. The method for producing a silicone polymer according to claim 1 or 2, wherein the ketone solvent is methyl isobutyl ketone.

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