JP2009059651A - Silsesquioxane based insulating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silsesquioxane based insulating material capable of forming an insulating film of high dielectric constant, and yet, with surface smoothness hardly damaged. <P>SOLUTION: The material contains polysilsesquioxane with a structure represented by formula (1). In the formula (1), x and y are an integer of any number, showing a composition ratio as in the case of a copolymer, becoming a single polymer in the case of: Za=Zb, that is, x+y. R denotes hydrogen or an alkyl group with the carbon number of 1 to 3, Za denotes a hydrocarbon group and an aromatic hydrocarbon group with the carbon number of 1 to 8, a glycidyl group, a cyano group or a mercapto group, and Zb is a glycidyl group, a cyano group or a mercapto group in case the Za is a hydrocarbon group, and is the same as the Za in case the Za is a glycidyl group, a cyano group or a mercapto group. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an insulating material used for, for example, a gate insulating film of an organic TFT (thin film transistor), and more particularly to a silsesquioxane-based insulating material capable of obtaining an insulating film having a high dielectric constant.

  In order to enable the organic TFT to be driven at a low voltage, it is strongly required that the gate insulating film has a high dielectric constant. Conventionally, various materials have been studied as insulating materials constituting organic TFTs. Patent Document 1 below discloses polysilsesquioxane as an insulating material used for such applications.

In the production of an insulating film made of polysilsesquioxane, a solution containing alkoxysilane, a catalyst for promoting hydrolysis of alkoxysilane and a solvent is prepared, and hydrolysis polycondensation is allowed to proceed. A solution containing sesquioxane is obtained. Thereafter, this solution is applied and baked to obtain an insulating film made of polysilsesquioxane.
JP 2006-216792 A

  In manufacturing a conventional polysilsesquioxane insulating film, for example, methyltriethoxysilane, phenyltriethoxysilane, or the like has been used as the alkoxysilane. Therefore, the obtained polysilsesquioxane had a methyl group or a phenyl group as a substituent.

  However, such an insulating film made of polysilsesquioxane is excellent in electrical insulation, but has a low dielectric constant. As described above, it is strongly desired that the gate insulating film of the organic TFT has a high dielectric constant. A conventional insulating film made of polysilsesquioxane cannot meet such a demand.

  Therefore, when the insulating film made of polysilsesquioxane is used as a gate insulating film, the power consumption of the organic TFT has to be increased.

  Therefore, attempts have been made to increase the dielectric constant by mixing inorganic oxide particles having a high dielectric constant with polysilsesquioxane. However, when inorganic oxide particles are added, unevenness due to the presence of the inorganic oxide particles tends to occur on the surface of the insulating film to be formed. Therefore, there has been a problem that the surface smoothness of the gate insulating film is lowered and the characteristics of the organic TFT are deteriorated.

  An object of the present invention is to provide a silsesquioxane-based insulating material that can form an insulating film having a high dielectric constant and that does not impair surface smoothness in view of the above-described state of the prior art. is there.

  The silsesquioxane-based insulating material according to the present invention includes polysilsesquioxane having a structure represented by the following formula (1).

  In the formula (1), x and y are arbitrary integers and indicate a composition ratio in the case of a copolymer. When Za = Zb, a homopolymer is formed, and thus x + y. R represents hydrogen or an alkyl group having 1 to 3 carbon atoms, Za represents a hydrocarbon group having 1 to 8 carbon atoms, an aromatic hydrocarbon group, a glycidyl group, a cyano group, or a mercapto group, and Zb represents a hydrocarbon in which Za is a hydrocarbon. When it is a group, it is a glycidyl group, a cyano group or a mercapto group, and when Za is a glycidyl group, a cyano group or a mercapto group, it is the same as Za.

  Preferably, Za is the hydrocarbon group, and Zb is a kind of substituent selected from a glycidyl group, a cyano group, and a mercapto group. In the case where Za is a hydrocarbon group, the water repellency of the finally obtained insulating film can be improved.

  The silsesquioxane-based insulating material according to the present invention may further include a solvent that dissolves the polysilsesquioxane, and in that case, the polysilsesquioxane in which the polysilsesquioxane is dissolved in the solvent. A silsesquioxane insulating film can be easily obtained by applying an oxan solution and heating.

  The silsesquioxane insulating material according to the present invention may be an insulator obtained by applying and baking the polysilsesquioxane. That is, the silsesquioxane-based insulating material of the present invention includes not only an insulator such as an insulating film formed by coating and baking, but also the specific polysilene before obtaining such an insulating film or insulator. It may be sesquioxane or a solution containing polysilsesquioxane, and all of these should be included.

  Details of the present invention will be described below.

  The silsesquioxane-based insulating material according to the present invention includes polysilsesquioxane having a structure represented by the above-described formula (1). Actually, in the synthesis of the specific polysilsesquioxane, as shown in the following reaction formula A or reaction formula B, the alkoxysilane is hydrolyzed in the presence of an acid catalyst, water and an aprotic solvent. Perform polycondensation. As a result of this synthesis, a polysilsesquioxane-based solution can be obtained. An insulator such as a silsesquioxane insulating film can be obtained by applying and baking the polysilsesquioxane solution. The hydrolysis polycondensation proceeds by maintaining the solution at a temperature of about 50 to 70 ° C. Moreover, the temperature at the time of baking should just be about 150-170 degreeC, Therefore, a silsesquioxane type | system | group insulating film can be obtained with a low-temperature process.

  In the above reaction formula A, R in the alkoxy group OR in the alkoxysilane on the left side is an alkyl group having 1 to 3 carbon atoms, preferably a methyl group or an ethyl group, and a plurality of ORs may be the same. , May be different. Za is a hydrocarbon group having 1 to 8 carbon atoms, an aromatic hydrocarbon group, a glycidyl group, a cyano group, a mercapto group, or a substituent containing one of these. The substituent containing one of these means a substituent in which a hydrocarbon group is further bonded to a glycidyl group, a cyano group, or a mercapto group. For example, a glycidylpropyl group, a glycidylhexyl group, a cyanomethyl group, a cyanoethyl group, a mercaptomethyl group, a mercaptophenyl group, etc. shall be said. Zb is a glycidyl group, a cyano group or a mercapto group or a substituent containing one of these when Za is a hydrocarbon group, and is the same as Za when Za is a glycidyl group, a cyano group or a mercapto group It is. Although it does not specifically limit as said hydrocarbon group as Za, More specifically, a methyl group, an ethyl group, a propyl group, a hexyl group, a phenyl group etc. can be mentioned.

  On the right side of the reaction formula A, a copolymer having the structural formula of the above formula (1) is obtained, where x and y are arbitrary integers indicating the composition ratio.

  The above reaction formula B shows the reaction in the case of Za = Zb in the above reaction formula A. In the case of Za = Zb, as shown in Reaction Formula B, a homopolymer is obtained. In this case, a homopolymer having a polymerization degree of x + y is obtained.

  Preferably, Za is a hydrocarbon group, and Zb is a kind of substituent selected from a glycidyl group, a cyano group, and a mercapto group. In the case where Za is a hydrocarbon group, the water repellency of the finally obtained insulating film can be increased.

  The alkoxysilane used as the starting material is not particularly limited as long as the specific polysilsesquioxane is given. Examples of such alkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, glycidyltrimethoxysilane, glycidyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane. Examples include methoxysilane, vinyltriethoxysilane, mercaptopropyltrimethoxysilane, mercaptopropyltriethoxysilane, cyanoethyltrimethoxysilane, and cyanoethyltriethoxysilane.

  In the polysilsesquioxane having the structure represented by the above formula (1), when Za and Zb are the same, a kind of alkoxysilane is used as a starting material as shown in the reaction formula B. When Za and Zb are different, in order to introduce the substituent Za and the substituent Zb, as shown in Reaction Formula A, an alkoxysilane having the substituent Za and an alkoxysilane having the substituent Zb are used as starting materials. Used. This point will be clarified by reaction formulas for the synthesis of various specific polysilsesquioxanes described later.

(Acid catalyst)
In the present invention, an acid catalyst is used to promote hydrolysis and hydrolysis polycondensation of the alkoxysilane. It does not specifically limit about an acid catalyst, An inorganic acid may be used and an organic acid may be used. Examples of inorganic acids include nitric acid, hydrochloric acid, sulfuric acid and the like. Examples of the organic acid include formic acid, acetic acid, and succinic acid. Preferably, if acid remains after completion of the reaction, the condensation stability is deteriorated. Formic acid having a low boiling point, high volatility and a small pKa is preferred as the acid catalyst.

  The acid catalyst needs to volatilize at a temperature not higher than the baking temperature during baking described later.

  The amount of the acid catalyst used is not particularly limited as long as sufficient catalytic action can be exerted, but is preferably 0.1 mol or more, more preferably, 1 mol of the one or more alkoxysilanes. It is preferable to blend 0.3 mol or more. In addition, if there are too many acid catalysts, the finally obtained silsesquioxane insulating film or insulator may be deteriorated by the presence of an acid, so the ratio is 1 mol or less with respect to one or more alkoxysilanes. It is desirable to use in.

(water)
In order to obtain the silsesquioxane insulating material of the present invention, it is necessary to add water to the starting material in order to promote hydrolysis of the alkoxysilane. Although it does not specifically limit as long as it can cause the hydrolysis of the said alkoxysilane, It is desirable to add water in the ratio of 2-6 mol with respect to 1 mol of 1 or more types of alkoxysilane. If it is less than 2 moles, hydrolysis may not proceed sufficiently, and if it exceeds 6 moles, hydrolysis may proceed too quickly, possibly hindering the progress of hydrolysis polycondensation. More preferably, water is used in a ratio of 2.5 to 4 moles with respect to 1 mole of one or more alkoxysilanes.

(solvent)
In the silsesquioxane-based insulating material according to the present invention, when the polysilsesquioxane having the specific structure is synthesized, in addition to the alkoxysilane, the acid catalyst, and water, by adding an appropriate solvent, The hydrolysis rate can be lowered moderately, and the hydrolysis polycondensation can surely proceed. Examples of such aprotic solvents include toluene, xylene, propylene glycol monomethyl ether acetate (PGMEA), and the like. In particular, in order to obtain good film forming properties, it is preferable to use PGMEA which is a high boiling point solvent.

  The amount of the solvent used is desirably in the range of 100 to 300 parts by weight with respect to one or more alkoxysilanes. If the amount is less than 100 parts by weight, it may be difficult to cause hydrolysis and hydrolysis polycondensation to proceed at an appropriate reaction rate. If the amount exceeds 300 parts by weight, it may require a long time for reduced pressure and distillation. is there.

(Synthesis of various polysilsesquioxanes having the structure represented by formula (1))
As described above, in synthesizing the specific polysilsesquioxane, first, one or two alkoxysilanes are mixed with an acid catalyst, water, and a solvent to obtain a solution. Hydrolysis proceeds by maintaining this solution at a temperature of 0-50 ° C. If it is less than 0 ° C., the hydrolysis may not proceed sufficiently, and if it exceeds 50 ° C., the hydrolysis reaction proceeds at a stretch and an unreacted alkoxy group remains. The hydrolysis time is preferably about 10 to 60 minutes. If it is less than 10 minutes, the hydrolysis may not proceed sufficiently, and if it exceeds 60 minutes, the reaction does not proceed any further, and therefore it may be unnecessary time.

  Subsequent to the hydrolysis step, the solution is maintained at a temperature of 50 to 70 ° C., and hydrolysis polycondensation proceeds. If it is less than 50 ° C., hydrolysis polycondensation may not proceed easily, and if it exceeds 70 ° C., the condensation reaction proceeds rapidly, which may cause gelation or coloration of the solution. More preferably, it may be heated to a temperature of 50 to 70 ° C.

  The hydrolysis polycondensation time is desirably 1 to 6 hours, and more preferably 2 to 3 hours.

  Examples of the method of heating to a temperature of 50 to 70 ° C. include a method of heating the solution with an appropriate heat source.

  Preferably, the solution is decompressed and the hydrolysis polycondensation proceeds under reduced pressure.

  As the hydrolysis polycondensation proceeds, a solution containing polysilsesquioxane having a specific structure of the present invention can be obtained. Synthesis reactions of various polysilsesquioxanes having the structure represented by the above formula (1) obtained as described above are represented by the following reaction formulas C to J. That is, each polysilsesquioxane shown on the right side of Reaction Formulas C to J has a glycidyl group, a mercapto group, or a cyano group as a substituent.

  In this case, as shown in Reaction Formula C, polysilsesquioxane may be performed by polycondensation of a kind of alkoxysilane having a glycidyl group. Further, as shown in Reaction Formula D, a skeleton in which methyltrimethoxysilane having no glycidyl group and trimethoxysilane having a glycidyl group are polycondensed and the methyl group is bonded to silicon as a substituent, and a glycidyl group May be a copolycondensate containing a skeleton bonded to silicon as a substituent. That is, depending on the structure of the resulting polysilsesquioxane, only one kind of alkoxysilane may be used as described above, and the alkoxysilane having the substituent Za and the alkoxysilane having the substituent Zb are hydrolyzed. Decomposition copolycondensation may be performed.

(Use)
Various insulators including a silsesquioxane insulating film can be obtained by applying and baking the specific polysilsesquioxane solution having the structure represented by the formula (1). An insulator including such a silsesquioxane insulating film has not only high insulation resistance but also high dielectric constant.

  Therefore, the above-described insulating film or insulator as the silsesquioxane-based insulating material of the present invention can be suitably used, for example, as a gate insulating film of an organic TFT requiring a high dielectric constant. Moreover, as long as a high dielectric constant and a high insulation resistance are required, it can be suitably used as an insulating material for not only the organic TFT gate insulating film but also various semiconductor devices and devices other than the semiconductor device.

  Since the silsesquioxane-based insulating material according to the present invention includes a specific polysilsesquioxane having a structure represented by the above formula (1), an insulating film or an insulator is formed by a low-temperature process using a sol-gel method. In addition, the insulation resistance of the obtained insulating film or insulator is not only sufficiently high, but also the dielectric constant is increased. Therefore, it is possible to provide an insulating material that is not only excellent in electrical insulation, such as an organic TFT, but also optimal for applications that require a high dielectric constant.

  In addition, since the silsesquioxane insulating material according to the present invention has a high dielectric constant, it is not necessary to add inorganic oxide particles to increase the dielectric constant. Accordingly, the smoothness of the surface of the obtained insulating film or insulator is hardly damaged.

  In addition, since it can be baked at a relatively low temperature of 170 ° C. or lower, that is, an insulating film or an insulator can be formed by a low-temperature process, the present invention is applied to a flexible substrate made of polyimide or the like that easily deteriorates at a high temperature. An insulating film or an insulator made of the silsesquioxane insulating material of the invention can be formed without degrading the flexible substrate. Therefore, it is also possible to provide an insulating material that is most suitable for an application in which an insulating film or an insulator is formed on the surface of a material that is easily deteriorated by high-temperature treatment.

  Hereinafter, the present invention will be clarified by giving specific examples and comparative examples of the present invention with reference to the drawings.

[Experimental Example I]
(Comparative Example 1)
In a 100 mL flask, 10.0 g (73 mmol) of methyltrimethoxysilane and 10 g of propylene glycol monomethyl ether (PGMEA) were added and stirred at room temperature to obtain a solution. To this solution, 1.02 g (22 mmol) of formic acid and 3.97 g (220 mmol) of distilled water were added as catalysts, and the mixture was maintained at room temperature for 30 minutes for hydrolysis. Thereafter, the hydrolyzed solution is maintained at a temperature of 70 ° C. for 1 hour to proceed with hydrolysis polycondensation, and further maintained at a pressure of 200 mmHg, while distilling off the by-produced alcohol and further for 2 hours. Hydrolysis polycondensation was performed. Thus, as shown by the following reaction formula K, the polysilsesquioxane described in the right side of the reaction formula K was synthesized, and a solution in which the polysilsesquioxane was dissolved in PGMEA was obtained.

(Example 1)
A 100 mL flask was charged with 3.03 g (13 mmol) of 3-glycidoxypropyltrimethoxysilane, 7.01 g (51 mmol) of methyltrimethoxysilane, and 10 g of propylene glycol monomethyl ether (PGMEA) at room temperature. To obtain a solution. To this solution, 0.89 g (19 mmol) of formic acid and 3.47 g (193 mmol) of distilled water were added as catalysts and maintained at room temperature for 30 minutes for hydrolysis. The hydrolyzed solution was maintained at 70 ° C. for 1 hour to allow hydrolysis polycondensation to proceed. Furthermore, it maintained for 2 hours under the pressure of 200 mmHg, alcohol byproduced was distilled off, and hydrolysis polycondensation was advanced. In this way, poly (methyl-co-3-glycidoxypropyl) silsesquioxane was synthesized according to the above-mentioned reaction formula D, and the poly (methyl-co-3-glycidoxypropyl) silsesquioxane was synthesized. Sun's PGMEA solution was obtained.

(Example 2)
As starting materials, 3-glycidoxypropyltrimethoxysilane (8.71 g, 37 mmol) and methyltrimethoxysilane (5.02 g, 37 mmol) were used, and the amount of PGMEA added was changed to 14 g. In the same manner as in Example 1 except that the amount of formic acid added was changed to 0.88 g (19 mmol) and the amount of distilled water added was 3.47 g (193 mmol), poly (methyl-co-3- A PGMEA solution of glycidoxypropyl) silsesquioxane was obtained.

(Example 3)
As starting materials, 12.2 g (51 mmol) of 3-glycidoxypropyltrimethoxysilane and 1.75 g (13 mmol) of methyltrimethoxysilane were used, and the addition amount of PGMEA was changed to 14 g. Poly (methyl-co-3) in the same manner as in Example 1 except that the amount of formic acid added was changed to 1.03 g (22 mmol) and the amount of distilled water added was 3.98 g (221 mmol). -Glycidoxypropyl) silsesquioxane in PGMEA solution was obtained.

Example 4
To a 100 mL flask, 5.02 g (21 mmol) of 3-glycidoxypropyltrimethoxysilane and 5 g of toluene were added and stirred at room temperature to obtain a toluene solution of 3-glycidoxypropyltrimethoxysilane. To this solution, 0.31 g (7 mmol) of formic acid and 1.15 g (64 mmol) of distilled water were added as catalysts and maintained at room temperature for 30 minutes for hydrolysis. Thereafter, the hydrolyzed solution is maintained at 70 ° C. for 1 hour to proceed with hydrolysis polycondensation, and further maintained under a pressure of 70 mmHg for 2 hours. Distilling off by-produced methanol and toluene, hydrolysis is performed. Polycondensation was performed and then dissolved in PGMEA. In this way, a PGMEA solution of poly (3-glycidoxypropyl) silsesquioxane was obtained according to the above reaction formula C.

  As described above, each silsesquioxane-based insulating material of Comparative Example 1 and Examples 1 to 4 shown in Table 1 described later was obtained.

[Experimental Example II]
(Example 5)
A 100 mL flask was charged with 5.01 g (21 mmol) of 3-glycidoxypropyltrimethoxysilane, 4.22 g (21 mmol) of phenyltrimethoxysilane, and 9.3 g of toluene as a solvent, and stirred at room temperature. Thus, a toluene solution of alkoxysilane was obtained. To this solution, 0.59 g (13 mmol) of formic acid and 2.30 g (128 mmol) of distilled water were added as catalysts, and the mixture was maintained at room temperature for 30 minutes for hydrolysis. Thereafter, the solution is maintained at a temperature of 70 ° C. for 1 hour to proceed with hydrolysis polycondensation, and further maintained under a pressure of 70 mmHg for 2 hours to distill off by-produced alcohol and toluene while distilling off by-products. The polycondensation proceeded further. Thereafter, it was dissolved in PGMEA. In this manner, a toluene solution of poly (phenyl-co-3-glycidoxypropyl) silsesquioxane was obtained according to the reaction shown in Reaction Formula E described above.

(Example 6)
According to Reaction Formula F described above, except that 4.42 g (21 mmol) of hexyltrimethoxysilane was used instead of 4.22 g of phenyltrimethoxysilane, poly (hexyl- A toluene solution of (co-3-glycidoxypropyl) silsesquioxane was obtained. As described above, silsesquioxane-based insulating materials of Examples 5 and 6 shown in Table 2 described later were obtained.

  In Table 2 below, not only Example 5 and Example 6 but also the results for Example 2 described in Table 1 are described again. This is to facilitate comparison between the fifth and sixth embodiments and the second embodiment.

[Experimental Example III]
(Comparative Example 2)
A 100 mL flask was charged with 4.12 g (25 mmol) of triethoxysilane, 7.02 g (51 mmol) of methyltrimethoxysilane, and 12 g of PGMEA, and stirred at room temperature to obtain a PGMEA solution of alkoxysilane. To this solution, 1.16 g (25 mmol) of formic acid and 4.51 g (250 mmol) of distilled water were added as catalysts and maintained at room temperature for 30 minutes for hydrolysis. Thereafter, after hydrolysis, the solution is maintained at a temperature of 50 ° C. for 1 hour to proceed with hydrolysis polycondensation, and further maintained under a pressure of 150 mmHg for 2 hours to further distill off the by-produced alcohol. Hydrolysis polycondensation was allowed to proceed. Thus, as shown in the following reaction formula L, a PGMEA solution of poly (methyl-hydrogen) silsesquioxane was obtained.

(Comparative Example 3)
A 100 mL flask was charged with 10.0 g (51 mmol) of phenyltrimethoxysilane and 10 g of toluene, and stirred at room temperature to obtain a toluene solution of phenyltrimethoxysilane. To this solution, 0.69 g (15 mmol) of formic acid and 2.73 g (151 mmol) of distilled water were added as catalysts, and the mixture was maintained at room temperature for 30 minutes for hydrolysis. Thereafter, this solution is maintained at 70 ° C. for 1 hour to proceed with hydrolytic polycondensation, and further, by maintaining the solution for 2 hours under a pressure of 70 mmHg, while distilling off by-produced methanol and toluene, Furthermore, hydrolysis polycondensation was performed. In this way, polyphenylsilsesquioxane was synthesized as shown in the following reaction formula M.

(Comparative Example 4)
Instead of phenyltrimethoxysilane, 10.0 g (53 mmol) of vinyltrimethoxysilane was used, the amount of formic acid added was 0.75 g (16 mmol), and the amount of distilled water added was 2.84 g (158 mmol). Except for this, polyvinyl silsesquioxane was synthesized according to the following reaction formula N in the same manner as in Comparative Example 3.

(Example 7)
Into a 100 mL flask, 10.0 g (51 mmol) of mercaptopropyltrimethoxysilane and 10 g of PGMEA were added and stirred at room temperature to obtain a PGMEA solution of mercaptopropyltrimethoxysilane. To this solution, 0.71 g (15 mmol) of formic acid and 2.75 g (153 mmol) of distilled water were added as a catalyst, and the solution was maintained at room temperature for 30 minutes for hydrolysis. Thereafter, the solution is maintained at a temperature of 70 ° C. for 1 hour, the hydrolysis polycondensation proceeds, and further maintained under a pressure of 200 mmHg for 2 hours, thereby further distilling off the by-produced methanol and further hydrolysis. Polycondensation was performed. In this way, a PGMEA solution of polymercaptopropylsilsesquioxane was obtained according to the reaction formula G described above.

(Example 8)
A 100 mL flask was charged with 2.01 g (9.3 mmol) of 2-cyanoethyltriethoxysilane, 1.27 g (9.3 mmol) of methyltrimethoxysilane, and 3.3 g of PGMEA, and stirred at room temperature. An alkoxysilane solution was obtained. To this solution, 0.27 g (5.8 mmol) of formic acid and 1.01 g (56 mmol) of distilled water were added as a catalyst, and the solution was kept at room temperature for 30 minutes for hydrolysis. Thereafter, the solution is maintained at a temperature of 70 ° C. for 1 hour to proceed with hydrolysis polycondensation, and further maintained under a pressure of 200 mmHg for 2 hours, thereby distilling off the by-produced alcohol and further adding water. Decomposition polycondensation was performed. In this way, a PGMEA solution of the above-described reaction formula H poly (methyl-co-2-cyanoethyl) silsesquioxane was obtained.

Example 9
The amount of 2-cyanoethyltriethoxysilane was 2.00 g (9.2 mmol), 1.85 g (9.3 mmol) of phenyltrimethoxysilane was used instead of methyltrimethoxysilane, and the solvent Except that 3.9 g of toluene was used instead of PGMEA, a PGMEA solution of poly (phenyl-co-2-cyanoethyl) silsesquioxane was prepared according to Reaction Formula I described above in the same manner as in Example 8. Obtained.

(Example 10)
The blending amount of 2-cyanoethyltriethoxysilane was 5.13 g (236 mmol), 4.87 g (236 mmol) of hexyltrimethoxysilane was used instead of methyltrimethoxysilane, and PGMEA was used as a solvent. Except for using 10 g of toluene, adding 0.65 g (5.8 mmol) of formic acid as a catalyst, and adding 2.55 g (142 mmol) of distilled water, Example 8 and Similarly, a PGMEA solution of poly (hexyl-co-2-cyanoethyl) silsesquioxane was obtained according to Reaction Formula J described above.

(Example 11)
The blending amount of 2-cyanoethyltriethoxysilane was 4.00 g (18.4 mmol), the blending amount of methyltrimethoxysilane was 0.63 g (4.6 mmol), and the blending amount of PGMEA was 4 .6 g, the amount of formic acid was 0.32 g (7.0 mmol), and the amount of distilled water was 1.24 g (69 mmol). In accordance with Reaction Formula H, a PGMEA solution of poly (methyl-co-2-cyanoethyl) silsesquioxane was obtained.

Example 12
The amount of 2-cyanoethyltriethoxysilane was 1.01 g (4.6 mmol), the amount of methyltrimethoxysilane was 2.53 g (18.6 mmol), and the amount of PGMEA added was 3.5 g. Except that the blending amount of distilled water is 1.25 g (70 mmol), the blending amount of formic acid is 0.32 g (7.0 mmol) and the blending amount of distilled water is 1.25 g (70 mmol). Except for the above, a PGMEA solution of poly (methyl-co-2-cyanoethyl) silsesquioxane was obtained in the same manner as in Example 8 according to Reaction Formula H.

  As described above, each silsesquioxane-based insulating material described in Comparative Examples 2 to 4 and Examples 7 to 12 shown in Table 3 below was obtained.

(Evaluation of Examples and Comparative Examples)
Aluminum was deposited on the upper surface of the slide glass as a lower electrode. Next, a polysilsesquioxane solution as a silsesquioxane insulating material of a comparative example or an example is spin-coated on the upper surface of the surface on which the lower electrode is formed, and baked at a temperature of 150 ° C. for 1 hour. A silsesquioxane insulating material having a thickness of 200 to 800 nm was formed. Aluminum was deposited as an upper electrode on the upper surface of the silsesquioxane insulating film. Thus, the laminated body by which the silsesquioxane type insulating film was laminated | stacked on the upper electrode and lower electrode which consist of aluminum was obtained. About the said laminated body sample, the dielectric constant of the silsesquioxane type insulation film between an upper electrode and a lower electrode was measured using the impedance analyzer. The dielectric constant was determined with an impedance analyzer in the frequency range of 10 mHz to 1 MHz at a voltage of 100 mV. Expression (1) is an expression for obtaining a dielectric constant, and ε ₀ is a vacuum dielectric constant, which is 8.85 × 10 ¹² .

ε = Cd / ε ₀ S (1)
In Tables 1 and 2 below, the contact angle of water with respect to the insulating film is measured five times, and the results calculated by the average are also shown. A larger contact angle indicates higher water repellency.

  About the polysilsesquioxane of the Example and the comparative example, the weight average molecular weight (Mw) and dispersion ratio (Mw / Mn) were measured using the gel permeation chromatograph (GPC). Mn represents a number average molecular weight.

  The results are shown in Tables 1 to 3.

Moreover, the frequency dependence of the dielectric constant calculated | required with the said impedance analyzer is shown in FIGS. 1 and FIG. 2 are diagrams showing the frequency dependence of the dielectric constant in the insulating films obtained in Comparative Example 1 and Examples 1 to 4, and in FIG. 1, in the range of 0.01 to 10 ⁵ Hz. In FIG. 2, the dielectric constant dependency in the range of 100 to 10 ⁵ Hz is shown.

As is clear from FIGS. 1 and 2, in Examples 1 to 4, the dielectric constant is increased as compared with Comparative Example 1. As can be seen from FIG. 2, in Examples 1 to 3, the dielectric constant is substantially constant within a practical frequency range of 100 to 10 ⁵ Hz. 3 and 4 are diagrams showing the frequency dependence of the dielectric constant in Example 2 and Example 5. In FIG. 3, the results in the range of 0.01 to 10 ⁵ Hz are shown in FIG. Results of -10 ⁵ Hz are shown. It can be seen that the dielectric constant of Example 5 is substantially constant over a wider frequency range than that of Example 2. However, as is clear from FIG. 4, it can be seen that the dielectric constant is substantially constant in both Example 2 and Example 5 in the practical frequency range of 100 to 10 ⁵ Hz.

FIGS. 5 and 6 are diagrams showing the frequency dependence of the dielectric constant of the insulating films of Examples 8 and 9. FIGS. 5 and 6 also show the results of Comparative Example 1 for comparison. Figure 5 shows the results of the range of 0.01 to 10 ⁵ Hz, Figure 6 shows the results in the range of 100 to 10 ⁵ Hz. As apparent from FIGS. 5 and 6, compared with Comparative Example 1, Examples 8 and 9 have a very high dielectric constant and a small frequency dependency of the dielectric constant, which is a particularly practical frequency range. It can be seen that the dielectric constant is substantially constant at 100 to 10 ⁵ Hz.

  As is clear from Table 1, in Comparative Example 1, the dielectric constant ε was as low as 4.4, whereas according to Examples 1 to 4, the dielectric constant was higher than that in Comparative Example 1. It is found that the dielectric constant ε is dramatically increased to 10.4 or more, particularly when the ratio of glycidyl groups to methyl groups is more than 1: 1.

  Further, as is apparent from Table 1, when the ratio of methyl group to glycidyl group is changed, the contact angle with respect to water decreases as the ratio of glycidyl group increases, and the water repellency deteriorates. Therefore, by reducing the proportion of the glycidyl group, the water repellency can be increased although the dielectric constant tends to be lowered. Therefore, when water repellency is required, the ratio of glycidyl groups is desirably 1/2 or less of the total of methyl groups and glycidyl groups, and more desirably 1/5 or less. However, in order to sufficiently increase the dielectric constant, as described above, it is desirable that the glycidyl group is ½ or more in the total of the methyl group and the glycidyl group.

  As is clear from Table 2, when the substituent Za is a methyl group, a phenyl group or a hexyl group, even if the ratio to the glycidyl group is all 1: 1, the hydrocarbon group constituting the substituent Za It can be seen that the contact angle differs depending on the type. In particular, in order to increase the contact angle and increase the water repellency of the insulating film, a phenyl group is preferable to a methyl group, and a hexyl group is more preferable. This is considered to be because the larger the size of the hydrocarbon group as the substituent Za, the higher the hydrophobicity.

  Further, as is apparent from Table 3, it can be seen that even when a cyanoethyl group containing a cyano group is used as the substituent Zb, the dielectric constant of the insulating film can be effectively increased. Furthermore, it can be seen that even when a mercaptopropyl group is used as a substituent, the dielectric constant ε is 5.6, which is higher than that of Comparative Example 1. That is, it can be understood that the dielectric constant can be effectively increased by the polarity even when a cyano group or a mercapto group is used as the substituents Za and Zb in the polysilsesquioxane in addition to the glycidyl group. .

It is a figure in which the dielectric constant of the insulating film obtained by the comparative example 1 and Examples 1-4 shows the frequency dependence in a 0.01-10 < ⁵ > Hz frequency range. It is a figure in which the dielectric constant of the insulating film obtained by the comparative example 1 and Examples 1-4 shows the frequency dependence in a 100-10 < ⁵ > Hz frequency range. It is a figure which shows the frequency dependence in the dielectric constant of the insulating film obtained in Example 2, 5 in a 0.01-10 < ⁵ > Hz frequency range. It is a figure which shows the frequency dependence in the dielectric constant of the insulating film obtained in Example 2, 5 in a 100-10 < ⁵ > Hz frequency range. It is a figure which shows the frequency dependence in the dielectric constant of the dielectric film of the insulating film obtained by the comparative example 1 and Examples 8 and 9 in a 0.01-10 < ⁵ > Hz frequency range. It is a figure which shows the frequency dependence in the dielectric constant of the insulating film obtained by the comparative example 1 and Example 8, 9 in the frequency range of 100-10 < ⁵ > Hz.

Claims (4)

A silsesquioxane-based insulating material comprising polysilsesquioxane having a structure represented by the following formula (1):

In the formula (1), x and y are arbitrary integers and indicate a composition ratio in the case of a copolymer. When Za = Zb, a homopolymer is formed, and thus x + y. R represents hydrogen or an alkyl group having 1 to 3 carbon atoms, Za represents a hydrocarbon group and aromatic hydrocarbon group having 1 to 8 carbon atoms, or a glycidyl group, a cyano group or a mercapto group, or one of these. Zb is a group containing a glycidyl group, a cyano group or a mercapto group or one of them when Za is a hydrocarbon group, and Za is a group containing a glycidyl group, a cyano group or a mercapto group or one of these Is the same as Za.   The silsesquioxane insulating material according to claim 1, wherein Za is the hydrocarbon group, and Zb is a glycidyl group, a cyano group, a mercapto group, or a substituent containing one of these.   The silsesquioxane-based insulating material according to claim 1, further comprising a solvent that dissolves the polysilsesquioxane.   The silsesquioxane-based insulating material according to any one of claims 1 to 3, which is an insulator obtained by applying and baking the polysilsesquioxane.

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