JP2010078924A - Photosensitive resin composition for forming polymer optical waveguide, optical waveguide, and method for forming optical waveguide pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive resin composition for forming an optical waveguide which has low transmission loss and capable of inexpensively forming a waveguide pattern excellent in preciseness of the shape, and to provide an optical waveguide, and a method for forming an optical waveguide pattern. <P>SOLUTION: The photosensitive resin composition for forming an optical waveguide contains at least an amide compound expressed in the formula (1) (wherein, R<SP>1</SP>denotes 1-20C alkyl group or aromatic hydrocarbon group and R<SP>2</SP>-R<SP>5</SP>denote hydrogen atom, halogen atom or 1-4C alkyl group independently), polymer having an epoxy group, and photooxide generator. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical waveguide used for optical devices, optical interconnections, optical wiring boards, optical / electrical hybrid circuit boards, and the like, and a photosensitive resin composition for forming optical waveguides. And an optical waveguide pattern forming method.

  In recent years, the Internet and digital home appliances have spread rapidly, and it is required to increase the capacity and speed of information processing in communication systems and computers, and high-speed transmission of high-capacity data using high-frequency signals has been studied. However, in order to transmit large-capacity signals with high-frequency signals, the conventional electrical wiring has a large transmission loss. Therefore, an optical transmission system has been studied extensively, and it will be used for wiring between computers, devices, and communications within a board. It is said. Among the elements that realize this optical transmission system, the optical waveguide is a basic component in optical elements, optical interconnections, optical wiring boards, optical / electrical hybrid circuit boards, etc. High performance and low cost are demanded.

  Conventionally, quartz waveguides and polymer waveguides are known as optical waveguides. Of these, quartz waveguides have the characteristic of very low transmission loss, but they have disadvantages in terms of manufacturing processes and costs, such as high processing temperatures in the manufacturing process and difficulty in producing large-area waveguides. ing.

  On the other hand, since the polymer waveguide has advantages such as ease of processing and a large degree of freedom in material design, a polymer material such as PMMA (polymethyl methacrylate), an epoxy resin, a polysiloxane derivative, or a fluorinated polyimide is used. Things have been considered. For example, Patent Document 1 and Patent Document 2 describe polymer waveguides using an epoxy compound. Patent Document 3 describes a waveguide using a polysiloxane derivative.

  However, in general, polymer waveguides have low heat resistance, and problems such as large transmission loss have been pointed out in the wavelength region of 600 to 1600 nm used in optical communications. In order to solve this problem, for example, studies have been made on reducing transmission loss by chemical modification such as deuteration or fluorination of a polymer, or using a polyimide derivative having heat resistance. However, for example, deuterated PMMA has low heat resistance, and fluorinated polyimide has excellent heat resistance. However, in order to form a waveguide pattern, a dry etching process is required in the same manner as a quartz waveguide. Has the disadvantage of becoming high.

JP-A-10-170738 Japanese Patent Laid-Open No. 11-337752 JP-A-9-124793

  Therefore, in forming an optical waveguide using a photosensitive resin, a photosensitive resin composition for forming an optical waveguide, an optical waveguide, which has a low transmission loss, and can be used to form a waveguide pattern with high shape accuracy and low cost. There is a need for a method of forming an optical waveguide pattern.

  Therefore, the technical problem of the present invention is to use a photosensitive resin composition for forming an optical waveguide, which can accurately form a waveguide pattern, and the formed optical waveguide has excellent transmission characteristics (low propagation loss). To provide an optical waveguide pattern forming method.

  As a result of investigations to achieve the above object, the inventors of the present invention have developed a photosensitive resin composition containing a specific structure amide compound, a polymer having an epoxy group, and a photoacid generator as constituents of an optical waveguide. By using it as a resin composition for forming one or both of the core layer and the clad layer, a suitable refractive index is imparted to each layer, the transmission loss of the waveguide is low, and the pattern shape of the waveguide is reduced. The present invention was completed by finding that it can be formed with high accuracy.

  That is, the photosensitive resin composition for forming an optical waveguide of the present invention that achieves the above object comprises at least an amide compound represented by the following general formula (1), a polymer having an epoxy group, and an acid by light irradiation. And at least a photoacid generator that is generated.

（式中、Ｒ^１は炭素数１〜２０のアルキル基または芳香族炭化水素基を表し、Ｒ^２〜Ｒ^５はそれぞれ独立に水素原子、ハロゲン原子、または炭素数１〜４のアルキル基を表す。）

(In the formula, R ¹ represents an alkyl group having 1 to 20 carbon atoms or an aromatic hydrocarbon group, and R ^{2 to} R ⁵ each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. .)

  The photosensitive resin composition for forming an optical waveguide of the present invention is characterized in that the polymer having an epoxy group is a polymer having at least a structural unit represented by the following general formula (2): .

（式中、Ｒ^６は水素原子またはメチル基を表し、Ｒ^７はエポキシ基を有する炭化水素基を表す。）

(Wherein R ⁶ represents a hydrogen atom or a methyl group, and R ⁷ represents a hydrocarbon group having an epoxy group.)

  In addition to the amide compound, the polymer having an epoxy group, and the photoacid generator, the photosensitive resin composition for forming an optical waveguide of the present invention is not limited to the epoxy polymer represented by the general formula (2). It is characterized by including the epoxy compound of this.

  The photosensitive resin composition for forming an optical waveguide of the present invention is a group consisting of alumina, silica, glass fiber, glass beads, silicone, titanium oxide, and metal oxide in addition to the polymer, photoacid generator, and epoxy compound. It contains at least one additive selected from more.

  The optical waveguide pattern forming method of the present invention for achieving the above object includes a first clad layer forming step of forming a lower clad layer on a substrate, and the photosensitive resin composition for forming an optical waveguide of the present invention. A coating step for coating the lower clad, a pre-baking step for fixing the resin composition on the substrate, an exposure step for selectively exposing the resin composition, and a heat treatment for promoting an acid-catalyzed reaction in the exposed region. And at least a second clad layer forming step of forming an upper clad layer on the resin composition layer after baking. Further, after the heat treatment step, development may be performed, and a development step for removing the unexposed portion and post-baking may be further performed to further include a post-baking step for forming the core layer.

  The photosensitive resin composition for forming an optical waveguide according to the present invention can form a waveguide pattern with high accuracy, and the formed optical waveguide has excellent transmission characteristics (low propagation loss). Can be used.

  Hereinafter, the photosensitive resin composition for forming an optical waveguide and the method for forming an optical waveguide pattern of the present invention will be described.

<Photosensitive resin composition for optical waveguide formation>
The photosensitive resin composition for forming an optical waveguide of the present invention (hereinafter referred to as photosensitive resin composition) includes at least an amide compound represented by the following general formula (1) of formula 3 and a polymer having an epoxy group and light: It contains an acid generator and can usually be prepared by mixing the amide compound, a polymer and a photoacid generator.

（式中、Ｒ^１は炭素数１〜２０のアルキル基または芳香族炭化水素基を表し、Ｒ^２〜Ｒ^５はそれぞれ独立に水素原子、ハロゲン原子、または炭素数１〜４のアルキル基を表す。）

(In the formula, R ¹ represents an alkyl group having 1 to 20 carbon atoms or an aromatic hydrocarbon group, and R ^{2 to} R ⁵ each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. .)

In formula (1), R ¹ represents an alkyl group having 1 to 20 carbon atoms or an aromatic hydrocarbon group, and R ^{2 to} R ⁵ each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. Represents. Examples of the alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, 2,2-dimethylpropyl group, and n-hexyl group. , N-octyl group, n-decyl group, heptadecyl group and the like. Examples of the aromatic hydrocarbon group include a phenyl group, a tolyl group, a 4-trifluoromethylphenyl group, a biphenyl group, and a naphthyl group. Examples of the halogen atom include a fluorine atom and a chlorine atom. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a tert-butyl group.

  Examples of the amide compound represented by the general formula (1) include, but are not limited to, the examples shown by the following chemical formulas (a) to (i). These compounds may be used alone or in combination of two or more.

  In order to obtain the amide compound represented by the general formula (1), it can be synthesized by reacting an acid chloride and an amino compound in tetrahydrofuran (THF) solvent in the presence of pyridine or N, N-diisopropylethylamine. .

  The content of the amide compound is usually 5 to 80% by mass, preferably 10 to 70% by mass, based on the total sum of all components including itself. Moreover, you may use individually or in mixture of 2 or more types.

  Moreover, as a polymer which has an epoxy group used for the photosensitive resin composition of this invention, the polymer which has a structural unit which has an epoxy group represented by General formula (2) of following Chemical formula 5 formula is mentioned.

（式中、Ｒ^６は水素原子またはメチル基を表し、Ｒ^７はエポキシ基を有する炭化水素基を表す。）

(Wherein R ⁶ represents a hydrogen atom or a methyl group, and R ⁷ represents a hydrocarbon group having an epoxy group.)

In the above formula (2), R ⁶ represents a hydrogen atom or a methyl group, and R ⁷ represents a hydrocarbon group having an epoxy group. Examples of the hydrocarbon group having an epoxy group include a glycidyl group, 3,4-epoxy-1-cyclohexylmethyl group, 5,6-epoxy-2-bicyclo [2,2,1] heptyl group, and 5 (6) -epoxy. Ethyl-2-bicyclo [2,2,1] heptyl group, 5,6-epoxy-2-bicyclo [2,2,1] heptylmethyl group, 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyl group, 3,4-epoxytricyclo [5.2.1.0 ^2,6] decyl oxyethyl group, 3,4-epoxy-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecyl group, 3,4 epoxy tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecyl methyl group and the like.

  The polymer having the structural unit of the general formula (2) is a known polymerization method, for example, solution polymerization, suspension polymerization, bulk polymerization, etc., having a corresponding epoxy group-containing hydrocarbon group (meth) acrylate ester. The polymerization may be performed by After the polymerization, it is desirable to purify by a known purification method in order to remove unreacted monomers, polymerization initiators and the like. Moreover, the structural unit of formula (2) may be one kind or a combination of two or more kinds.

  Furthermore, the polymer used in the present invention can contain structural units other than the general formula (2). For example, structural units derived from vinyl monomers such as (meth) acrylic acid, (meth) acrylic acid ester and styrene can be mentioned.

The structural unit represented by the general formula (2) is preferably in the range of 10 to 100% with respect to the number of structural units of the whole polymer.

  Moreover, 1,000 or more are preferable and, as for the mass mean molecular weight (Mw) of the polymer obtained, 4,000 or more are more preferable. Moreover, 1,000,000 or less is preferable and 500,000 or less is more preferable.

  The content rate of a polymer is 10-90 mass% normally with respect to the sum total of all the components including itself, Preferably it is 20-80 mass%. Moreover, you may use individually or in mixture of 2 or more types.

  The photosensitive resin composition of the present invention may further contain an epoxy compound other than the polymer having an epoxy group, in addition to the amide compound, the polymer having an epoxy group, and a photoacid generator. Examples of the epoxy compound other than the polymer having an epoxy group include bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, Propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, 1,2-cyclohexanecarboxylic acid diglycidyl ester, 3,4- Epoxycyclohexanecarboxylic acid 3,4-epoxycyclohexylmethyl, trisepoxypropyl isocyanurate, 2- Poxyethylbicyclo [2,2,1] heptylglycidyl ether, ethylene glycol bis (2-epoxyethylbicyclo [2,2,1] heptyl) ether, bis (2-epoxyethylbicyclo [2,2,1] heptyl) Examples include ether.

  Moreover, when adding these epoxy compounds, the content rate is 1-70 mass% normally with respect to the sum total of all the components including itself, Preferably it is 5-60 mass%. Moreover, you may use individually or in mixture of 2 or more types.

  The photoacid generator used in the present invention is preferably a photoacid generator that generates an acid upon irradiation with light used for exposure, and the mixture with the polymer or the like in the present invention is sufficient for an organic solvent. If it melt | dissolves and can form a uniform coating film by film forming methods, such as a spin coat, using the solution, it will not restrict | limit in particular. Moreover, you may use individually or in mixture of 2 or more types.

  Examples of photoacid generators that can be used in the present invention include triarylsulfonium salt derivatives, diaryliodonium salt derivatives, dialkylphenacylsulfonium salt derivatives, nitrobenzyl sulfonate derivatives, sulfones of N-hydroxynaphthalimide. Examples thereof include acid esters and sulfonic acid ester derivatives of N-hydroxysuccinimide, but are not limited thereto.

  The content of the photoacid generator is based on the total of the amide compound, polymer, epoxy compound and photoacid generator from the viewpoint of realizing sufficient sensitivity of the photosensitive resin composition and enabling good pattern formation. 0.1 mass% or more is preferable, and 0.5 mass% or more is more preferable. On the other hand, it is preferably 15% by mass or less, more preferably 7% by mass or less, from the viewpoint of realizing the formation of a uniform coating film and not impairing the properties of the waveguide.

  In addition to the amide compound, polymer, photoacid generator, and epoxy compound, the photosensitive resin composition of the present invention may contain various additives as long as the characteristics as an optical waveguide are not impaired. Examples of such additives include alumina, silica, glass fiber, glass beads, silicone, titanium oxide, and metal oxide. By adding these additives, the crack resistance and heat resistance can be improved, the elastic modulus can be reduced, and the warpage of the waveguide can be improved.

  In addition, when preparing the said photosensitive resin composition, a suitable solvent is used as needed. The solvent is not particularly limited as long as the photosensitive resin composition can be sufficiently dissolved and the solution can be uniformly applied by a method such as spin coating. Specifically, γ-butyrolactone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, 2-heptanone, 2-methoxybutyl acetate, 2-ethoxyethyl acetate, methyl pyruvate, ethyl pyruvate, 3 -Methyl methoxypropionate, ethyl 3-methoxypropionate, N-methyl-2-pyrrolidone, cyclohexanone, cyclopentanone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, ethylene glycol Monoisopropyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether and the like can be used. These may be used alone or in admixture of two or more.

  Furthermore, the photosensitive resin composition of the present invention can also be prepared by adding other components such as an adhesion improver and a coatability improver as necessary.

  The characteristic of the photosensitive resin composition of the present invention is that the photoacid generator contained in the composition generates an acid upon exposure, the crosslinking reaction is promoted by this acid, and then heat-cured to expose the composition. The difference in refractive index is caused between the part and the unexposed part. That is, the exposed portion is characterized by a lower refractive index than the unexposed portion. Further, a difference in solubility occurs between the exposed portion and the unexposed portion due to the difference in the degree of crosslinking, and it is possible to selectively remove only the unexposed portion by performing development processing.

<Method for forming optical waveguide pattern>
The production of the polymer optical waveguide according to the present invention will be described. The polymer optical waveguide is composed of a core having a high refractive index and a clad having a low refractive index. The polymer optical waveguide is formed in a shape surrounding the core with the clad, and is obtained by a waveguide pattern forming method including at least the following steps.

(1) a first cladding layer forming step of forming a lower cladding layer on an appropriate substrate;
(2) A coating process for coating the photosensitive resin composition of the present invention on the lower clad layer;
(3) a pre-baking step for pre-baking;
(4) Actinic radiation that irradiates actinic radiation such as ultraviolet rays to the photosensitive resin composition layer other than the region that becomes the core layer through a mask, that is, the region that should become the intermediate cladding layer formed on the side surface of the core layer Irradiation process;
(5) a heat treatment step of performing post-exposure heating;
(6) The order of the second clad layer forming step of forming an upper clad layer on the heated resin composition layer.

  Moreover, in this invention, you may form any one or both of the said lower clad and an upper clad by irradiating actinic radiation similarly using the photosensitive resin composition of this invention.

The polymer optical waveguide of the present invention can also be obtained by a conventionally known method for performing development processing. That is,
(1) a first cladding layer forming step of forming a lower cladding layer on an appropriate substrate;
(2) A coating process for coating the photosensitive resin composition of the present invention on the lower clad layer;
(3) a pre-baking step for pre-baking;
(4) an actinic radiation irradiation step of irradiating the photosensitive resin composition layer with actinic radiation such as ultraviolet rays to a region to be a core layer through a mask;
(5) a heat treatment step of performing post-exposure heating;
(6) a development step of developing and removing unexposed portions;
(7) performing a post-bake and forming a core layer;
(8) At least a second cladding layer forming step of forming intermediate and upper cladding layers on the core layer and lower cladding layer formed as described above. Further, either or both of the lower clad and the middle and upper clad may be formed by irradiating actinic radiation in the same manner using the photosensitive resin composition of the present invention. A composition that reduces the rate is selected and used.

  Below, the example of the manufacturing method of the polymer optical waveguide by this invention is demonstrated in detail using FIG.1 and FIG.2.

(A) Manufacturing method of polymer optical waveguide not including development step:
FIG. 1 is a cross-sectional view showing an example of a method for producing a polymer optical waveguide that does not include the developing step of the present invention.

  First, a lower clad layer is formed on an appropriate substrate. For example, as shown in FIG. 1A, the lower clad layer is formed by applying the photosensitive resin composition of the present invention on the substrate 1 and prebaking to form the photosensitive resin composition layer 2.

  Next, as shown in FIG. 1B, the lower cladding layer 3 is formed by exposing the entire surface to actinic radiation and performing a heat treatment (baking) step to lower the refractive index of the resin composition layer 2. . The lower cladding layer 3 may be obtained by actinic radiation or heat treatment using any other photosensitive resin composition having a refractive index equivalent to that of the lower cladding layer 3. In the present invention, examples of the substrate 1 include a silicon substrate, a glass substrate, a quartz substrate, a glass epoxy substrate, a metal substrate, a ceramic substrate, a polymer film, or a substrate in which a polymer film is formed on various substrates. However, it is not limited to these.

  Next, as shown in FIG.1 (c), the photosensitive resin composition 2 of this invention is apply | coated on the said lower clad layer 3, and the photosensitive resin composition layer 2 is formed by prebaking. The method for applying the photosensitive resin composition is not particularly limited, and for example, spin coating using a spin coater, spray coating using a spray coater, dipping, printing, roll coating, and the like can be used. The pre-baking step is a step for drying the applied photosensitive resin composition, removing the solvent in the photosensitive resin composition, and fixing the applied photosensitive resin composition. A prebaking process is normally performed at 60-160 degreeC.

  Next, as shown in FIG. 1 (d), the photosensitive resin composition layer 2 is irradiated with actinic radiation only to the region corresponding to the intermediate cladding layer 5 through a photomask 4, and further heat-treated, Only the region corresponding to the intermediate cladding layer 5 of the photosensitive resin composition is subjected to exposure and heat treatment to lower the refractive index.

  On the other hand, as shown in FIG. 1 (d), the region corresponding to the core layer 6 is not exposed and only heat treatment is performed, so the refractive index of the region corresponding to the core layer 6 is refracted compared to the region corresponding to the intermediate cladding layer 5. As a result, the intermediate cladding layer 5 having a low refractive index is formed, and the core layer 6 having a high refractive index is formed.

  The exposure step is a step of selectively exposing the photosensitive resin composition layer 2 through the photomask 4 and transferring the waveguide pattern on the photomask 4 to the photosensitive resin composition layer 2. Here, as the actinic radiation used for the entire surface exposure and the pattern exposure described below and later, ultraviolet rays, visible rays, excimer lasers, electron beams, X-rays and the like can be used, but actinic rays having a wavelength of 180 to 500 nm are preferable.

  Moreover, the heat processing process heated after exposure is normally performed at 80-250 degreeC in the air or inert gas atmosphere. Further, the heat treatment step of heating after exposure may be performed in one step or in multiple steps.

  Furthermore, as shown in FIG.1 (e), the photosensitive resin composition of this invention is apply | coated on the photosensitive resin composition layer 2 heated after exposure, actinic radiation is exposed to the whole surface, and it heat-processes. The refractive index is lowered, and the upper cladding layer 7 is formed as shown in FIG. The upper clad layer 7 may be obtained by actinic radiation or heat treatment using any other photosensitive resin composition having a refractive index equivalent to the refractive index thereof. In this way, a polymer optical waveguide formed by surrounding the core layer 6 having a high refractive index with the lower clad layer 3, the intermediate clad layer 5 and the upper clad layer 7 having a low refractive index can be produced. Thereafter, as shown in FIG. 1G, the polymer optical waveguide 10 can be obtained by removing the substrate 1 by a method such as etching. If a flexible polymer film or the like is employed as the substrate 1, a flexible polymer optical waveguide can be obtained.

(B) Method for producing polymer optical waveguide including development step:
FIG. 2 is a cross-sectional view sequentially showing an example of each step of the method for producing a polymer optical waveguide including the developing step of the present invention. First, the lower cladding layer 3 is formed on an appropriate substrate 1. For example, as shown in FIG. 2A, the lower cladding layer 3 is formed by applying the photosensitive resin composition of the present invention on the substrate 1 and pre-baking the photosensitive resin composition layer 2. Next, as shown in FIG. 2B, the resin layer 2 is lowered in refractive index by exposing the entire surface with ultraviolet rays and performing a heat treatment (baking) process, thereby forming the lower cladding layer 3. The lower cladding layer 3 may be obtained by actinic radiation or heat treatment using any other photosensitive resin composition having a refractive index equivalent to that of the lower cladding layer 3.

  In the present invention, examples of the substrate 1 include a silicon substrate, a glass substrate, a quartz substrate, a glass epoxy substrate, a metal substrate, a ceramic substrate, a polymer film, or a substrate in which a polymer film is formed on various substrates. Although it can be used, it is not limited to these.

  Next, as shown in FIG. 2C, the photosensitive resin composition of the present invention is applied on the lower clad layer 3 and prebaked to form a photosensitive resin composition layer 2 '. For the formation of the photosensitive resin composition layer 2 ′, a composition having a refractive index higher than that of the lower cladding layer 3 is selected and used. The refractive index can be adjusted, for example, by copolymerizing a polymer having an epoxy group contained in the photosensitive resin composition. The method for applying the photosensitive resin composition is not particularly limited, and for example, spin coating using a spin coater, spray coating using a spray coater, dipping, printing, roll coating, and the like can be used. In the pre-baking step, the applied photosensitive resin composition is dried, the solvent in the photosensitive resin composition is removed, and the applied photosensitive resin composition is fixed as the photosensitive resin composition layer 2 ′. It is this process. A prebaking process is normally performed at 60-160 degreeC.

  Next, as shown in FIG. 2 (d), the photosensitive resin composition layer 2 ′ is irradiated with actinic radiation through a photomask 4 to a region corresponding to the core layer 6 ′, and further post-exposure heat treatment is performed. Then, development is performed with an organic solvent to remove the unexposed portion, and then post baking is performed to form a core layer 6 ′ having a high refractive index on the lower cladding layer 3. In this case, the composition of the photosensitive resin composition used for forming the core layer 6 ′ is appropriately adjusted so that the refractive index is higher by exposure and heat treatment than the photosensitive resin composition used for forming the cladding layer. deep.

  The exposure step is a step of selectively exposing the photosensitive resin composition layer 2 ′ through the photomask 4 and transferring the waveguide pattern on the photomask 4 to the photosensitive resin composition layer 2 ′. As the actinic radiation used for the entire surface exposure and pattern exposure described below and later, ultraviolet rays, visible rays, excimer lasers, electron beams, X-rays and the like can be used, but actinic rays having a wavelength of 180 to 500 nm are preferable.

  Moreover, the heat treatment process for heat treatment after exposure is usually performed at 80 to 160 ° C. in air or in an inert gas atmosphere.

  The development step is a step of forming the core layer 6 ′ by dissolving and removing the unexposed portion of the photosensitive resin composition layer 2 ′ with an organic solvent. The difference in solubility (dissolution contrast) between the exposed portion and the unexposed portion of the photosensitive resin composition layer 2 ′ in the developer is caused by the above-described exposure and post-exposure heating steps. By utilizing this dissolution contrast, a core pattern in which an unexposed portion of the photosensitive resin composition is dissolved and removed can be obtained. Here, specific examples of the organic solvent include γ-butyrolactone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, 2-heptanone, 2-methoxybutyl acetate, 2-ethoxyethyl acetate, and pyrubin. Methyl acetate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, N-methyl-2-pyrrolidone, cyclohexanone, cyclopentanone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, Ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether It can be used. These may be used alone or in admixture of two or more. As the developing method, paddle, dipping, spraying and the like are possible. After the development step, the formed pattern is rinsed with water or an organic solvent used in development.

  Moreover, a post-baking process is normally performed at 100-250 degreeC in air or inert gas atmosphere. Further, the post-baking process may be performed in one stage or in multiple stages.

  Further, as shown in FIG. 2 (e), the photosensitive resin composition of the present invention is applied on the core layer 6 'formed, and the entire surface is exposed to actinic radiation and heat-treated to reduce the refractive index. As shown in FIG. 2F, the intermediate clad and the upper clad (intermediate and upper clad layer 5 ′) are formed in a lump. The intermediate and upper clad layers 5 ′ may be obtained by using any other photosensitive resin composition having a refractive index equivalent to the refractive index thereof, and by ultraviolet rays or heat treatment. In this manner, a polymer optical waveguide formed by surrounding the core layer 6 'having a high refractive index with the lower clad layer 3, the middle and upper clad layers 5' having a low refractive index can be produced.

  Further, as shown in FIG. 2G, the polymer optical waveguide 20 can be obtained by removing the substrate 1 by a method such as etching. If a flexible polymer film or the like is employed as the substrate 1, a flexible polymer optical waveguide can be obtained.

  As described above, the photosensitive resin composition of the present invention can form a waveguide pattern with high accuracy, and the formed optical waveguide has excellent transmission characteristics (low propagation loss). it can.

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

(Synthesis Example 1)
Synthesis of an amide compound having the following structure, that is, an amide compound in which R ¹ is a t-butyl group and R ^{2 to} R ⁵ are hydrogen atoms in the general formula (1) represented by the following chemical formula 6.

  22.9 g of o-aminophenol and 40.68 g of N, N-diisopropylethylamine are dissolved in 250 ml of THF and cooled on ice. Thereto, 25.3 g of pivaloyl chloride is added dropwise, and the mixture is stirred for 2 hours under ice cooling and overnight at room temperature. The reaction mixture is poured into 1 L of water and the organic layer is extracted with 600 ml of diethyl ether. The diethyl ether layer is washed with 0.2N hydrochloric acid, brine, and water in that order and dried over magnesium sulfate. Diethyl ether was distilled off under reduced pressure, and the solidified residue was recrystallized with ethyl acetate to obtain 23.72 g of white powder N- (2-hydroxyphenyl) pivalamide (yield 58%).

(Synthesis Example 2)
Synthesis of an amide compound having the following structure, that is, an amide compound in which R ¹ is a 2,2-dimethylpropyl group and R ^{2 to} R ⁵ are hydrogen atoms in the general formula (1) represented by the following chemical formula 7.

  Similar to Synthesis Example 1, except that t-butylacetyl chloride was used instead of pivaloyl chloride to obtain white N- (2-hydroxyphenyl) t-butylacetylamide (yield) 47%).

(Synthesis Example 3)
In the above-mentioned general formula (2) represented by the following chemical formula (8), R ⁶ is a hydrogen atom and R ⁷ is a 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyloxyethyl group. Synthesis of a polymer that is

20 g of 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyloxyethyl acrylate is dissolved in 200 ml of THF, and 0.62 g of 2,2′-azobis (isobutyronitrile) is added thereto, and an argon atmosphere is used. Heat to reflux for 2 hours. After allowing to cool, it was reprecipitated in 1000 ml of hexane, and the precipitated polymer was filtered off and purified again by reprecipitation to obtain 16 g of the desired polymer (yield 80%). Moreover, the mass mean molecular weight (Mw) was 19800 (polystyrene conversion) by GPC analysis, and dispersion degree (Mw / Mn) was 2.65.

(Synthesis Example 4)
A polymer having the following structure, that is, in the above general formula (2) represented by the following chemical formula 9, R ⁶ is a hydrogen atom and R ⁷ is a 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyloxydecyl group. Synthesis of a polymer composed of 50 mol% of structural units and 50 mol% of structural units of 5-acryloyloxy-2,6-norbornanelactone.

  17.77 g of 3,4-epoxytricyclodecyloxyethyl acrylate and 14 g of 5-acryloyl-2,6-norbornanecarbolactone are dissolved in 180 ml of THF, and 1.104 g of 2,2′-azobis (isobutyronitrile) is dissolved therein. And heated to reflux under an argon atmosphere for 1 hour. After standing to cool, it was reprecipitated in 1.5 L of methanol, and the precipitated polymer was filtered off and purified again by reprecipitation to obtain 27.32 g of the target polymer (yield 86%). Moreover, the mass mean molecular weight (Mw) was 16800 (polystyrene conversion), and dispersion degree (Mw / Mn) was 3.22 by GPC analysis.

(Synthesis Example 5)
A polymer having the following structure, that is, a structural unit represented by the following formula (10), wherein R ⁶ is a hydrogen atom and R ⁷ is a 3,4-epoxytricyclo [5.2.1.0 ^2,6 ] decyl group. Of a polymer composed of 50 mol% and 50 mol% of structural units of phenoxyethyl acrylate.

  25 g of 3,4-epoxytricyclodecyl acrylate and 21.82 g of phenoxyethyl acrylate are dissolved in 140 ml of THF, and 1.118 g of 2,2′-azobis (isobutyronitrile) is added thereto, and the mixture is kept under an argon atmosphere for 2 hours. Heated to reflux. After allowing to cool, the mixture was reprecipitated in 1500 ml of hexane, the precipitated polymer was filtered, and purified again by reprecipitation to obtain 40.3 g of the target polymer (yield 86%). Moreover, the weight average molecular weight (Mw) was 9300 (polystyrene conversion), and dispersion degree (Mw / Mn) was 2.26 by GPC analysis.

Example 1
A photosensitive resin composition having the composition shown in Table 1 below was prepared.

  The above mixture was filtered using a 0.45 μm Teflon (registered trademark) filter to prepare a photosensitive resin composition. The photosensitive resin was spin-coated on a 4-inch silicon substrate and baked in an oven at 110 ° C. for 20 minutes to form two coating films. Next, the first sheet was exposed to ultraviolet rays (wavelength λ = 350 to 450 nm), then heat-treated at 90 ° C. for 10 minutes, and then baked at 150 ° C. for 30 minutes and further at 220 ° C. for 1 hour in a nitrogen atmosphere. The remaining sheet was heat-treated at 90 ° C. for 10 minutes without being irradiated with ultraviolet rays, and then baked at 150 ° C. for 30 minutes and further at 220 ° C. for 1 hour in a nitrogen atmosphere. Next, the refractive index of 633 nm was measured for each sample using a prism coupler manufactured by Metricon. As a result, the refractive index of the film irradiated with ultraviolet rays was 1.512, and the refractive index of the film not irradiated with ultraviolet rays was 1.521. From this result, even if it was the same resin composition, it was shown that the photosensitive resin composition of this invention shows a difference in a refractive index by ultraviolet irradiation and non-irradiation.

(Example 2)
A photosensitive resin composition having the composition shown in Table 2 below was prepared.

The above mixture was filtered using a 0.45 μm Teflon (registered trademark) filter to prepare a photosensitive resin composition. Next, the photosensitive resin was spin-coated on a 4-inch silicon substrate and baked in an oven at 110 ° C. for 20 minutes to form a film with a thickness of 20 μm. Next, ultraviolet light (wavelength λ = 350 to 450 nm) is exposed to 500 mJ / cm ^{2 on the} entire surface, and after the exposure, baked in an oven at 90 ° C. for 10 minutes, and further in a nitrogen atmosphere at 150 ° C. for 1 hour, further at 220 ° C. A lower clad layer was formed by baking for a period of time. Next, the photosensitive resin composition was spin-coated on the lower clad layer, and baked in an oven at 110 ° C. for 30 minutes to form a film with a thickness of 50 μm. Next, ultraviolet light (wavelength λ = 350 to 450 nm) was exposed to 500 mJ / cm ² through a photomask. After the exposure, baking was performed in an oven at 90 ° C. for 10 minutes, and further, baking was performed at 150 ° C. for 1 hour and further at 220 ° C. for 1 hour in a nitrogen atmosphere to form a patterned core layer and intermediate cladding layer. Next, the photosensitive resin was spin-coated on the core layer and the intermediate cladding layer, and baked in an oven at 110 ° C. for 20 minutes to form a film with a thickness of 20 μm. Next, ultraviolet light (wavelength λ = 350 to 450 nm) is exposed to 500 mJ / cm ^{2 on the} entire surface, and after the exposure, baked in an oven at 90 ° C. for 10 minutes, and further in a nitrogen atmosphere at 150 ° C. for 1 hour, further at 220 ° C. The upper clad layer was formed by baking for a time, and a polymer optical waveguide was obtained.

  After the end face of this optical waveguide was diced with a dicer, the propagation loss of this optical waveguide was evaluated using the cutback method at a wavelength of 850 nm. The propagation loss was 0.5 dB / cm. The cross-sectional shape of the cladding layer was rectangular.

(Example 3)
A photosensitive resin composition having the composition shown in Table 3 below was prepared.

The above mixture was filtered using a 0.45 μm Teflon (registered trademark) filter to prepare a photosensitive resin composition. Next, the photosensitive resin was spin-coated on a 4-inch silicon substrate and baked in an oven at 110 ° C. for 20 minutes to form a film with a thickness of 20 μm. Next, ultraviolet light (wavelength λ = 350 to 450 nm) was exposed to 600 mJ / cm ^{2 on the} entire surface, and after the exposure, baked in an oven at 90 ° C. for 10 minutes, and further in a nitrogen atmosphere at 150 ° C. for 1 hour and further at 220 ° C. A lower clad layer was formed by baking for a period of time. Next, the photosensitive resin composition was spin-coated on the lower clad layer and baked in an oven at 110 ° C. for 20 minutes to form a film with a thickness of 50 μm. Next, ultraviolet rays (wavelength λ = 350 to 450 nm) were exposed to 600 mJ / cm ² through a photomask. After the exposure, baking was performed in an oven at 90 ° C. for 10 minutes, and further, baking was performed at 150 ° C. for 1 hour and further at 220 ° C. for 1 hour in a nitrogen atmosphere to form a patterned core layer and intermediate cladding layer. Next, the photosensitive resin was spin-coated on the core layer and the intermediate cladding layer, and baked in an oven at 110 ° C. for 20 minutes to form a film with a thickness of 20 μm. Next, ultraviolet light (wavelength λ = 350 to 450 nm) is exposed to the entire surface of 600 mJ / cm ² , and after exposure, baked in an oven at 90 ° C. for 10 minutes, and further in a nitrogen atmosphere at 150 ° C. for 1 hour and further at 220 ° C. The upper clad layer was formed by baking for a time, and a polymer optical waveguide was obtained.

  After the end face of this optical waveguide was diced with a dicer, the propagation loss of this optical waveguide was evaluated using the cutback method at a wavelength of 850 nm. The propagation loss was 0.55 dB / cm. The cross-sectional shape of the cladding layer was rectangular.

Example 4
A photosensitive resin composition for forming a lower clad and an upper clad having the composition shown in Table 4 below was prepared.

  Moreover, the photosensitive resin composition for core formation which consists of a composition shown in the following Table 5 was prepared.

The above mixture was filtered using a 0.45 μm Teflon (registered trademark) filter to prepare a photosensitive resin composition. Next, the lower clad forming photosensitive resin was spin-coated on a 4-inch silicon substrate and baked in an oven at 110 ° C. for 20 minutes to form a film having a thickness of 20 μm. Next, ultraviolet rays (wavelength λ = 350 to 450 nm) were exposed to the entire surface at 550 mJ / cm ² , and after exposure, baked in an oven at 90 ° C. for 10 minutes, and further at 150 ° C. for 1 hour and at 220 ° C. for 1 hour in a nitrogen atmosphere. A lower clad layer was formed by baking. Next, the core-forming photosensitive resin was applied by spin coating, and baked in an oven at 90 ° C. for 30 minutes to form a film having a thickness of 50 μm. Next, ultraviolet light (wavelength λ = 350 to 450 nm) was irradiated through a photomask at 600 mJ / cm ² and then baked in an oven at 90 ° C. for 10 minutes. Next, development was carried out by γ-butyrolactone for 3 minutes, followed by rinsing with pure water for 2 minutes. As a result, only the unexposed portion of the photosensitive resin film was dissolved and removed in the developer to obtain a core pattern. Next, the core layer was completely cured by baking at 150 ° C. for 1 hour and at 220 ° C. for 1 hour in a nitrogen atmosphere to form the core layer. Next, the lower clad forming photosensitive resin was spin-coated and baked in an oven at 110 ° C. for 20 minutes to form a film with a thickness of 20 μm. Next, ultraviolet rays (wavelength λ = 350 to 450 nm) were exposed to the entire surface at 550 mJ / cm ² , and after exposure, baked in an oven at 90 ° C. for 10 minutes, and further at 150 ° C. for 1 hour and at 220 ° C. for 1 hour in a nitrogen atmosphere. By baking, an upper cladding layer was formed to obtain a polymer optical waveguide.

  After the end face of this optical waveguide was diced with a dicer, the propagation loss of this optical waveguide was evaluated using the cutback method at a wavelength of 850 nm. The propagation loss was 0.35 dB / cm. The cross-sectional shape of the cladding layer was rectangular.

  As is clear from the above description, by using the photosensitive resin composition for forming a polymer optical waveguide of the present invention, an optical waveguide pattern can be accurately formed, and the formed optical waveguide has excellent transmission characteristics (low propagation loss). Therefore, it is suitable as a material for forming an optical waveguide.

It is a figure which shows an example of the manufacturing process of the polymer waveguide by the photosensitive resin composition by this invention, (a)-(g) is a schematic sectional drawing which shows each process in order. It is a figure which shows another example of the manufacturing process of the polymer waveguide by the photosensitive resin composition by this invention, (a)-(g) is a schematic sectional drawing which shows each process in order.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2, 2 'Photosensitive resin composition layer 3 Lower clad layer 4 Photomask 5 Middle clad layer 5' Middle and upper clad layer 6, 6 'Core layer 7 Upper clad layer

Claims (9)

A photosensitive resin composition for forming an optical waveguide, comprising at least an amide compound represented by the following general formula (1), a polymer having an epoxy group, and a photoacid generator.

(In the formula, R ¹ represents an alkyl group having 1 to 20 carbon atoms or an aromatic hydrocarbon group, and R ^{2 to} R ⁵ each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms. .) The photosensitive resin composition for forming an optical waveguide according to claim 1, wherein the polymer having an epoxy group includes at least a structural unit represented by the following general formula (2): A photosensitive resin composition for forming an optical waveguide.

(Wherein R ⁶ represents a hydrogen atom or a methyl group, and R ⁷ represents a hydrocarbon group having an epoxy group.)   The photosensitive resin composition for forming an optical waveguide according to claim 1 or 2, wherein the photosensitive resin composition for forming an optical waveguide further contains an epoxy compound. .   The photosensitive resin composition for forming an optical waveguide according to any one of claims 1 to 3, wherein the photosensitive resin composition for forming an optical waveguide includes alumina, silica, glass fiber, glass beads, silicone, A photosensitive resin composition for forming an optical waveguide, further comprising at least one additive selected from the group consisting of titanium oxide and metal oxide.   5. An optical waveguide having a core layer and a clad layer formed on the core layer, wherein either or both of the core layer and the clad layer are according to claim 1. An optical waveguide comprising a cured product of the photosensitive resin composition for forming an optical waveguide. A first cladding layer forming step of forming a lower cladding layer on the substrate;
An application step of applying the photosensitive resin composition for forming an optical waveguide according to any one of claims 1 to 4 on the lower clad layer;
A pre-baking process for pre-baking;
Actinic radiation irradiation step for irradiating the resin composition layer for forming an optical waveguide with actinic radiation to a region other than the core layer through a mask;
A heat treatment step for heating after exposure;
And an upper clad layer forming step of forming an upper clad layer on the heated resin composition layer.   7. The method for forming an optical waveguide pattern according to claim 6, wherein either one or both of the lower cladding layer and the upper cladding layer are cured after irradiating the optical waveguide forming resin composition with actinic radiation. A method of forming an optical waveguide pattern, characterized in that: A first cladding layer forming step of forming a lower cladding layer on the substrate;
An application step of applying the resin composition for forming an optical waveguide according to any one of claims 1 to 4 on the lower clad layer;
A pre-baking process for pre-baking;
Actinic radiation irradiating step of irradiating the region that becomes the core layer through the mask to the optical waveguide forming resin composition layer;
A heat treatment step for heating after exposure;
A development step of developing and removing unexposed areas;
A post-baking step of performing post-baking and forming a core layer;
And a second clad layer forming step of forming intermediate and upper clad layers on the core layer and the lower clad layer formed as described above.   9. The method for forming an optical waveguide pattern according to claim 8, wherein any one or both of the lower cladding layer and the middle and upper cladding layers are the resin composition for forming an optical waveguide and have a lower refractive index than the core layer. A method of forming an optical waveguide pattern, comprising: curing a composition having an effective composition after irradiation with actinic radiation.

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