JP2011114162A - Passivation film containing borazine frame, and display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device having a high performance passivation film, using a low dielectric constant film that excels in moisture resistance and reliability. <P>SOLUTION: The present invention relates to the passivation film for the display device containing polymer, having a borazine frame or the passivation film for the display device formed by compound and/or polymer having the borazine frame. The use of such a passivation film enables attaining thin films, turning into light weight, and cost reduction in manufacturing the display device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a passivation film formed as a surface protective film on the uppermost part of a display device, and a display device provided with the passivation film.

  In recent years, development of a thin film transistor using an organic material (organic semiconductor material) that exhibits semiconducting electrical conduction has been promoted.

  This thin film transistor has advantages such as being suitable for reduction in thickness and weight, flexibility, and low material cost, and is expected as a switching element for displays and the like.

  In such a thin film transistor, an inorganic insulating film such as silicon nitride, silicon oxide, or metal is usually used as a material for a passivation film provided on the outermost layer in order to protect the element surface (for example, Patent Document 1). However, these inorganic films have a problem that an apparatus for forming them is expensive or heat treatment at a high temperature is required, so that a thermal load is applied to the transistor portion. Further, the dielectric constant is about 7.0, and there is a problem that miniaturization of the transistor is limited.

  On the other hand, in the field of semiconductor devices, the importance of miniaturization technology for wiring is increasing due to high speed, large capacity, and low power consumption accompanying the high integration of LSI. For this reason, studies have been made to lower the dielectric constant of the interlayer insulating film.

JP-A-5-6890

  An object of the present invention is to find a low dielectric constant film excellent in moisture resistance and excellent in reliability and to provide a display device provided with a high-performance passivation film.

Such a problem was solved by adopting a passivation film containing a polymer having a borazine skeleton. Since the compound having a borazine ring skeleton has a low molecular polarizability, the formed film has a low dielectric constant, and the formed film is excellent in heat resistance and moisture resistance.

  The present invention includes a display device provided with the passivation film.

The present invention is characterized in that a passivation film including a polymer having a borazine skeleton represented by the following formula (1) is configured.

  As shown in the above formula (1), nitrogen (N) and boron (B) of the borazine ring each have one bond that does not form a borazine ring. There are no particular limitations on the elements or functional groups outside the ring that bind to the nitrogen and boron that form the borazine ring. Examples of the element and functional group bonded to nitrogen or boron forming the borazine ring include a hydrogen atom, a halogen atom, an alkyl group, an amino group, and a borazinyl group.

  The compound having a borazine skeleton may be a compound having one borazine ring or a compound having two or more borazine rings. Further, a polymer having a borazine skeleton may be used.

  Examples of the method for forming the passivation film include a coating method and a CVD method. As the CVD method, any known chemical vapor deposition method using heat, light, plasma, or the like can be employed. A coating method is preferred for simplifying the process. Examples of the coating method include spin coating, casting, micro gravure coating, gravure, bar coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, and flexographic printing. , Offset printing method, ink jet method, micro contact printing method, and the like, and one or more of them can be used in combination. Moreover, when manufacturing a bulk body (thick film having a thickness of several mm or more), a compound having a borazine skeleton and a polymer are poured into a mold and molded, and the obtained molded body is fired.

  When the step of applying by coating is included, it is preferable to use a polymer having a borazine skeleton. Use of a polymer having a borazine skeleton polymerized in a network improves the workability when forming a coating film using a coating method, compared to using only a compound having a non-polymerized borazine skeleton. To do. Moreover, when using a polymer, there exists an advantage that a uniform film | membrane is obtained easily. When only a compound having a borazine skeleton that is not polymerized is used, the film often becomes cloudy and it may be difficult to obtain a uniform film. Further, after film formation, further post-treatment may be required. If the coating is non-uniform, it may cause defects and performance degradation. Such an effect is very large from the viewpoints of cost and productivity in industrial mass production of the present invention.

  A polymer having a borazine skeleton can be formed using a compound having a borazine ring skeleton as a monomer. In the formula (1), a polymer having a borazine skeleton can be formed by bonding at least one of bonds not forming a borazine ring directly to another borazine ring or via an organic group. A polymerization method and a polymerization form are not particularly limited. The polymerization method is selected depending on the functional group bonded to the borazine ring. For example, when an amino group is bonded, a polymer can be synthesized by condensation polymerization as shown in Examples. When a vinyl group or a functional group containing a vinyl group is bonded to the borazine ring, for example, a polymer can be formed by radical polymerization using a polymerization initiator. The polymer may be a polymer obtained from a compound having a single borazine ring skeleton, or may be a copolymer obtained from a compound having two or more borazine ring skeletons. The form of the copolymer may be any of a random copolymer, a block copolymer, a graft copolymer, and the like. If a monomer having three or more functional groups capable of forming a bond with another monomer is used, it is possible to obtain a polymer in which the monomers are bonded in a network.

  When forming a compound having a borazine skeleton and a polymer on a passivation film, if necessary, it is mixed or dispersed with other components within a range that does not affect the effect of the present invention, and a composition is prepared. Can be used in the film forming process. Examples of the other components described above include inorganic or organic additives such as a curing catalyst, a wettability improver, a plasticizer, an antifoaming agent, a thickener, and a solvent.

  In the case of coating by dissolving or decomposing a compound having a borazine skeleton and a polymer, the solvent is not particularly limited. The compound and polymer having a borazine skeleton and other components added as needed are not particularly limited. For example, alcohols such as ethylene glycol and ethylene glycol nomomethyl ether; aromatic hydrocarbons such as toluene, benzene and xylene; hydrocarbons such as hexane, heptane and octane; tetrahydrofuran, diglyme, triglyme and tetraglyme are solvents. Can be used as These may be used individually by 1 type, and 2 or more types may be mixed and used for them. The amount of solvent used is not particularly limited, and may be determined according to the film forming means. For example, when a film is formed by spin coating, the solvent and the amount of the solvent may be determined so that the viscosity is suitable for spin coating.

  The compound and polymer having a borazine skeleton are formed into a film by being supplied to a desired site and dried. Drying can be performed by natural drying, vacuum drying, drying by heating, a method of blowing a gas (for example, an inert gas or the like), and the like. For example, it may be applied onto a substrate by spin coating and dried. If a coating with a desired thickness cannot be obtained by a single coating and drying, the coating and drying may be repeated until the desired thickness is obtained. Film formation conditions such as the spin coater rotation speed, drying temperature, and drying time are not particularly limited. Moreover, you may perform baking as needed.

  Preferably, the compound and polymer having a borazine skeleton of the present invention are a borazine ring-containing compound represented by the following formula (2) and a polymer obtained therefrom.

  R1, R3 and R5 bonded to boron (B) constituting the borazine ring are a hydrogen atom, an optionally substituted alkyl group, or a functional group represented by the following formula (3). R1, R3 and R5 may be the same or different. Moreover, R7 in Formula (3) is an alkyl group.

  The alkyl group that can be included as R1, R3, R5, and R7 can be a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms. Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, 1-methyl-ethyl, sec-butyl, tert-butyl. Group, neopentyl group, cyclohexyl group and the like. However, alkyl groups that can be included as R1, R3, R5, and R7 are not limited thereto.

  In the alkyl group that can be included as R1, R3, R5, and R7, a hydrogen atom may be substituted with another functional group without departing from the effects of the present invention. Functional groups include amino groups, isocyanate groups, vinyl groups, ethynyl groups, and the like.

  When it has a functional group represented by the formula (3), it is suitable for condensation polymerization of the borazine ring-containing compound represented by the formula (2). In that case, the borazine ring-containing compound used as a monomer preferably contains two or more functional groups of the formula (3). In order to obtain a network-like polymer, it is preferable to use a borazine ring-containing compound in which all of R1, R3, and R5 are functional groups represented by the formula (3). Even in the case of synthesizing a network polymer, it is not necessary that R1, R3, and R5 are functional groups represented by the formula (3) for all of the borazine ring-containing compounds used as monomers. . In the case of forming a film using a coating method, it is necessary to uniformly dissolve in an appropriate solvent. If the network-like polymer is three-dimensionally crosslinked at high density, the uniformity of the solvent and the solubility of the polymer in the solvent may be reduced. For this reason, according to the solvent to be used and the borazine ring containing compound to be used, it is good to control the degree of network form (crosslinking degree).

  R2, R4 and R6 bonded to nitrogen (N) constituting the borazine ring are a hydrogen atom or an alkyl group. R2, R4, and R6 may be the same or different. The alkyl group that can be included as R2, R4, and R6 is the same as the alkyl group that can be included as R1, R3, R5, and R7.

  Moreover, when it does not have a functional group represented by Formula (3), at least one of R1-R6 in Formula (2) contains a hydrogen atom. When hydrogen atoms are not contained in R1 to R6, polycondensation does not proceed, and a film having sufficient mechanical strength and moisture resistance may not be formed.

  Specific examples of the borazine ring-containing compound represented by the formula (2) include unsubstituted borazine; B, B ′, B ″ -tris (propylamino) borazine, B, B ′, B ″ -tris (hexylamino) ) Alkylaminoborazines such as borazine, B, B ′, B ″ -tris (methylamino) borazine, B, B ′, B ″ -tris (propylamino) -N, N ′, N ″ -trimethylborazine; mono Alkyl borazines such as -B-methyl borazine, di-B-methyl borazine, mono-N-ethyl borazine, di-N-methyl borazine, tri-N-propyl borazine, mono-N-di-B-methyl borazine; Can be mentioned.

  The compound and polymer having a borazine skeleton can be produced with appropriate consideration of known techniques. Therefore, in the present invention, the method for producing a compound having a borazine skeleton and a polymer is not particularly limited. For example, “Yoshiharu Kimura, Textiles and Industries, Vol. 52, No. 8, 341, 1996”, “Paine & Sneddon, Recent Developments in Borazine-Based Polymers”, “Inorganic and Organic Polymers 19”, “Organic and Organic Polymers” Reference can be made to known techniques described in the

  The passivation film of the present invention is used as a passivation film disposed in a thin film transistor portion of a display device such as an organic EL, LCD, or electronic paper. The passivation film made of the composition containing the borazine skeleton of the present invention is excellent in heat resistance and moisture resistance and has a low dielectric constant. Therefore, it is possible to form a single layer together with the flat layer on the passivation layer. It is not necessary to form an inorganic vapor deposition film or the like on this layer. FIG. 1 shows a structure of a general organic EL transistor, and FIG. 2 shows a structure in which a passivation layer and a flat layer are combined into one layer. Thus, the passivation film of the present invention can simplify the structure of the organic EL, reduce the manufacturing cost of the display device, and simplify the manufacturing process. The present invention includes a display device provided with a passivation film made of the composition containing the borazine skeleton of the present invention, and the configuration of the display device is not particularly limited.

  Next, the effects of the present invention will be described using examples. However, the technical scope of the present invention is not limited to the following examples.

[Synthesis Example 1]
B, B ′, B ″ -trichloroborazine (15 g) was dissolved in sufficiently dehydrated toluene (100 mL), and a mixed solution of n-propylamine (22 g), triethylamine (25 g) and toluene (100 mL) was added at room temperature. After dropwise addition, the mixture was stirred for 3 hours at 25 ° C. and further stirred for 3 hours at 60 ° C. After the resulting amine hydrochloride was removed by filtration, the solvent and unreacted amine were distilled off under reduced pressure. A yellow viscous liquid (22.5 g) of B, B ′, B ″ -tris (propylamino) borazine was obtained (see the following formula). The resulting compound was further stirred in xylene at 130 ° C. for 3 hours to advance the polycondensation reaction. After the reaction, the solvent was distilled off under reduced pressure to obtain a polymer 1 having a borazine skeleton, which is a polymer having repeating units bonded in a network form (see the following formula).

[Synthesis Example 2]
B, B ′, B ″ -trichloroborazine (15 g) was dissolved in sufficiently dehydrated toluene (100 mL), and a mixed solution of n-hexylamine (37 g), triethylamine (25 g) and toluene (100 mL) was added at room temperature. After dropwise addition, the mixture was stirred for 3 hours at 25 ° C. and further stirred for 3 hours at 60 ° C. After the resulting amine hydrochloride was removed by filtration, the solvent and unreacted amine were distilled off under reduced pressure. As a result, a yellow viscous liquid (30 g) of B, B ′, B ″ -tris (hexylamino) borazine was obtained. The resulting compound was further stirred in xylene at 130 ° C. for 3 hours to advance the polycondensation reaction. After the reaction, the solvent was distilled off under reduced pressure to obtain a polymer 2 having a borazine skeleton.

[Synthesis Example 3]
B, B ′, B ″ -trichloroborazine (15 g) was dissolved in 100 mL of sufficiently dehydrated toluene and added dropwise to a flask containing methylamine (16 g) kept at about −70 ° C. over 1 hour. After completion of the dropwise addition, the mixture was stirred for 3 hours at 25 ° C., and further stirred for 3 hours at 60 ° C. After removing the resulting amine hydrochloride by filtration, the solvent and unreacted amine were distilled off under reduced pressure, and B and B ′. , B ″ -tris (methylamino) borazine white viscous liquid (12 g) was obtained. The resulting compound was further stirred in xylene at 130 ° C. for 3 hours to proceed the polycondensation reaction. After distilling off under reduced pressure, a polymer 3 having a borazine skeleton was obtained.

[Synthesis Example 4]
B, B ′, B ″ -trichloro-N, N′N ″ -trimethylborazine (15 g) was dissolved in sufficiently dehydrated toluene (100 mL), and n-propylamine (14 g), triethylamine (23 g), toluene 100 mL was dissolved. Was added dropwise at room temperature over 1 hour. After completion of dropping, the mixture was stirred at 25 ° C. for 3 hours and at 60 ° C. for 3 hours. After the generated amine hydrochloride was removed by filtration, the solvent and unreacted amine were distilled off under reduced pressure, and yellow viscosity of B, B ′, B ″ -tris (propylamino) -N, N′N ″ -trimethylborazine was obtained. A liquid (17 g) was obtained. The resulting compound was further stirred in xylene at 130 ° C. for 3 hours to advance the polycondensation reaction. After the solvent was distilled off under reduced pressure, a polymer 4 having a borazine skeleton was obtained.

[Production conditions for passivation film]
Compounds 1-4 polymerized above were dissolved in sufficiently dried xylene to obtain a solution having a borazine ring-containing compound concentration of 10% by mass. This solution was applied to a silicon substrate at 3000 rpm using a spin coater and dried at 120 ° C. for 3 minutes. By repeating this operation 8 times, a film having a thickness of 1 μm was obtained. This film was baked at 350 ° C. for 30 minutes in an argon atmosphere with an oxygen concentration of 0.1 ppm or less to form a transparent and crack-free film.

Example 1
A film 1 was formed from the polymer 1 having a borazine skeleton obtained in Synthesis Example 1 in accordance with the above film forming conditions. A gold electrode was deposited on the coating 1, and the dielectric constant of the film was measured. In addition, the moisture resistance of the film was evaluated. The results are shown in Table 1. The moisture resistance evaluation was good by observing a change in appearance under the condition of 20 ° C. and 20% Rh.

(Example 2)
A film 2 was formed according to the procedure of Example 1 except that the polymer 2 having a borazine skeleton obtained in Synthesis Example 2 was used. Table 1 shows the measurement results of the dielectric constant and moisture resistance of the coating 2. The moisture resistance evaluation was good by observing a change in appearance under the condition of 20 ° C. and 20% Rh.

(Example 3)
A coating 3 was formed according to the procedure of Example 1 except that the polymer 3 having a borazine skeleton obtained in Synthesis Example 3 was used. Table 1 shows the measurement results of the dielectric constant and moisture resistance of the coating 3. The moisture resistance evaluation was good by observing a change in appearance under the condition of 20 ° C. and 20% Rh.

Example 4
A film 4 was formed according to the procedure of Example 1 except that the polymer 4 having a borazine skeleton obtained in Synthesis Example 4 was used. Table 1 shows the measurement results of the dielectric constant and moisture resistance of the coating 4. The moisture resistance evaluation was good by observing a change in appearance under the condition of 20 ° C. and 20% Rh.

It is a basic structural diagram of a thin film transistor for organic EL. FIG. 2 is a basic structural diagram of an organic EL thin film transistor in which a passivation layer and a flat layer are formed in one layer.

  DESCRIPTION OF SYMBOLS 1 ... Flat layer 2 ... Source electrode 3 ... Gate insulating layer 4 ... Amorphous silicon 5 ... Gate electrode 6 ... Glass substrate 7 ... Transparent electrode 8 ... Passivation layer 9 ... Drain electrode 10 ... Flat layer 11 ... Source electrode 12 ... Gate insulating layer 13 ... Amorphous silicon 14 ... Gate electrode 15 ... Glass substrate 16 ... Transparent electrode 17 ..Drain electrode

Claims (3)

A passivation film for a display device, comprising a polymer having a borazine skeleton. A passivation film for a display device obtained from a compound and / or polymer having a borazine skeleton. A display device using the passivation film according to claim 1.

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