JP4438369B2 - Radiation curable composition, optical waveguide and method for forming the same - Google Patents

Description

  The present invention relates to a radiation curable composition for producing an optical circuit used in the fields of optical communication, optical information processing, and the like, an optical waveguide using the composition, and a method for forming the optical waveguide.

In the multimedia era, transmission systems that use light as a transmission medium have become public communication networks, LANs (local area networks), and FAs (factory automation) in response to demands for large capacity and high speed information processing in optical communication systems and computers. ), Interconnects between computers, home wiring, etc.
The optical waveguides used in these transmission systems are used in optical devices, photoelectric integrated circuits (OEICs), optical integrated circuits (optical ICs) and the like for realizing large-capacity information transmission such as movies and moving images and optical computers, for example. It is a basic component. Optical waveguides have been intensively studied due to the large amount of demand. On the other hand, particularly high performance and low cost products are required.

  Conventionally known quartz optical waveguides and polymer optical waveguides are known as such optical waveguides. Among them, the silica-based optical waveguide has excellent transmission characteristics as compared with the polymer-based optical waveguide, but the vitrification process (at 1200 ° C. or higher) or the etching process performed following the deposition of oxide fine particles. Therefore, strict production conditions for a long time are required for production. On the other hand, a polymer-based optical waveguide can be easily formed into a thin film by a spin coating method, a dip coating method, or the like, and can be manufactured at a low temperature process by reactive ion etching (RIE) or photolithography. In particular, since an optical waveguide using photolithography can be manufactured in a short time, there is an advantage that it can be formed more easily and at a lower cost than a quartz-based optical waveguide.

  As one of these polymer-based optical waveguide materials, polysiloxane with high heat resistance has been proposed for some time. By introducing phenyl groups, methyl groups, ethyl groups, etc. into the polymer, the refractive index is controlled and crack resistance is improved. Has been achieved. In addition, there has also been a report of a radiation curable technique by introducing a radiation-sensitive group into a polysiloxane material that has been known as a thermosetting type (see Patent Document 1 and Patent Document 2). However, the C—H bond contained in an alkyl group such as a methyl group causes an increase in loss in that band because its second overtone appears in the 1.55 μm wavelength band. In order to avoid this, polysiloxanes that are all substituted with phenyl groups without using alkyl groups have been reported. However, since the hardness of the thin film increases, the loss is reduced, for example, cracks are easily generated during the production of the thin film. And preventing cracks were difficult.

On the other hand, prescriptions such as replacement of C—H bonds contained in polysiloxane with C—D bonds or C—F bonds have been reported, but since it is a thermosetting type, self-core formation by a technique such as photolithography is possible. However, it was necessary to form a core by a technique such as etching (see Patent Document 3 and Patent Document 4).
Furthermore, in such CD coupling and CF coupling, the third harmonic of the CD coupling still appears in the 1.55 μm wavelength band, making it difficult to reduce the loss, or introducing the CF group. As a result, there is a problem that peeling occurs at the interface between the core / cladding and the cladding / base.
JP 2000-66051 A JP-A-6-109936 Japanese Patent Laid-Open No. 4-157402 Japanese Unexamined Patent Publication No. 2000-230052

As described above, the conventional polymer-based optical waveguide is relatively easy to manufacture as compared with the quartz-based optical waveguide, but satisfies both low transmission loss and crack resistance, and is free from peeling and cracking. It has been required to have all the properties that can be used stably in the long term without generating.
In the present invention, in view of such circumstances, an object of the present invention is to obtain a material for quickly and easily forming an optical waveguide having excellent properties described above.

That is, the object of the present invention is a material having a small waveguide loss and excellent crack resistance, heat resistance, patterning property upon radiation irradiation, etc., for light having a wide range of wavelengths from the visible range to the near infrared range. And an optical waveguide formed using the same, and easily and inexpensively.
Another object of the present invention is to provide an optical waveguide forming method capable of forming such an optical waveguide in a short time and with a simple process.

As a result of intensive studies to solve the above problems, the present inventors have found that a radiation curable composition containing a siloxane oligomer having a non-hydrolyzable organic group containing a fluorine atom and a photoacid generator as constituent components, The present invention has been completed by finding that it is extremely suitable as a resin for forming an optical waveguide.
That is, the radiation curable composition for forming an optical waveguide of the present invention (invention 1) has the following components (A) and (B):
(A) at least one or more selected from the group consisting of a hydrolyzate of a hydrolyzable silane compound represented by the following general formula (1) and a condensate of the hydrolyzate;
(R ¹ ) Si (X) ₃ (1)
[In the general formula (1), R ¹ is a fluorinated alkyl group or fluorinated aryl group having a carbon number in the nonhydrolyzable is 1 to 12, X is a hydrolyzable group. ]
And (B) a radiation curable composition containing a photoacid generator, the silanol (Si-OH) occupying the bonding groups on all Si derived from the trifunctional hydrolyzable silane compound in the composition ) The group content is 10 to 50%.
Here, “trifunctional” means having three hydrolyzable groups.
If the radiation curable composition comprised in this way is used, an optical waveguide can be formed easily and cheaply, exhibiting the patterning property etc. which were excellent in the case of radiation irradiation. In addition, this optical waveguide has little waveguide loss and excellent characteristics such as crack resistance and heat resistance for light having a wide range of wavelengths from the visible range to the near infrared range.

［一般式（２）中、Ｒ^３は非加水分解性で炭素数が１〜１２のフッ素化アルキル基またはフッ素化アリール基である。］ Here, as said (A) component, what has the structure of following General formula (2) can be used, for example (Claim 2).

[In the general formula (2), R ³ is the number of carbon atoms in the nonhydrolyzable is 1-12 fluorinated alkyl group or fluorinated aryl group. ]

［一般式（４）及び（５）中、Ｒ^５はフェニル基、あるいはフッ素化フェニル基、Ｒ^６はフッ素原子を含んでいてもよい炭素数が１〜１２である非加水分解性の有機基であって、Ｒ^５と同じでもよい。］ Further, the formula (1) as ^{R 1} in, for _{example, CF 3 (CF 2) n} (CH 2) m [m is an integer of 0 to 5, n is an integer of 1 to 11, m + n is 1 ~ 11. ] Can be used (Claim 3).
Further, as the component (A), one having at least one structure selected from the group consisting of the following general formulas (4) and (5) can be used.

[In General Formulas (4) and (5), R ⁵ is a phenyl group or a fluorinated phenyl group, and R ⁶ is a non-hydrolyzable organic group having 1 to 12 carbon atoms which may contain a fluorine atom. And may be the same as R ⁵ . ]

The radiation curable composition of the present invention (invention 5) is configured such that the addition amount of the (B) photoacid generator is 0.01 to 15 parts by weight with respect to 100 parts by weight of the component (A). Can do.
The radiation curable composition includes a lower cladding layer, a core portion formed in a part of a region on the lower cladding layer, and an upper portion formed on the lower cladding layer so as to cover the core portion. The lower cladding layer and the core portion of an optical waveguide having a cladding layer, wherein the thickness of the lower cladding layer and the upper cladding layer is 3 to 50 μm, and the thickness of the core portion is 3 to 20 μm And at least one selected from the upper clad layer can be used as a radiation curable composition.
Method of forming an optical waveguide of the present invention (Claim 7), a lower cladding layer, a portion which is formed in the core portion of the region on said lower cladding layer, the lower cladding layer to cover the core portion In the method of forming an optical waveguide having an upper clad layer formed thereon, at least one selected from the lower clad layer, the core portion, and the upper clad layer is used as the radiation curable type. The optical waveguide is formed by irradiating with radiation after coating using the composition as a material.
An optical waveguide according to the present invention (invention 8 ) is formed on the lower cladding layer, a core portion formed in a part of a region on the lower cladding layer, and the lower cladding layer so as to cover the core portion. In the optical waveguide having an upper clad layer formed, at least one selected from the lower clad layer, the core portion, and the upper clad layer is made of the above-mentioned radiation curable composition. It is a feature.
The optical waveguide can be formed such that the thickness of the lower cladding layer and the upper cladding layer is 3 to 50 μm, and the thickness of the core portion is 3 to 20 μm.

According to the radiation curable composition of the present invention, the waveguide loss for light in a wide range in the near-infrared region is as low as 0.5 dB / cm or less, and is excellent in long-term stability with low waveguide loss. Can be manufactured.
Further, according to the radiation curable composition of the present invention, it has excellent transparency and heat resistance, does not cause peeling at the interface or generate cracks inside the waveguide, and has excellent shape accuracy. An optical waveguide can be manufactured.
Furthermore, according to the method for forming an optical waveguide of the present invention, an optical waveguide with little waveguide loss and excellent patternability, crack resistance and the like can be formed in a short time and with a simple process. Therefore, it is possible to provide an optical waveguide that is suitably used for manufacturing an optical circuit used in an optical communication system at low cost.

Hereinafter, the present invention will be described in detail.
[(A) component]
The component (A) of the present invention comprises at least one selected from the group consisting of a hydrolyzate of a hydrolyzable silane compound represented by the following general formula (1) and a condensate of the hydrolyzate. The silanol group content is preferably 1 to 10 mmol / g. Here, the hydrolyzate of the hydrolyzable silane compound means, for example, a product in which an alkoxy group is changed to a silanol group by a hydrolysis reaction, but also a part of silanol groups or silanol groups and alkoxy groups. It also means a partial condensate obtained by condensing.
(R ¹ ) Si (X) ₃ (1)
[In the general formula (1), R ¹ is a fluorinated alkyl group or fluorinated aryl group having a carbon number in the nonhydrolyzable is 1 to 12, X is a hydrolyzable group. ]
The component (A) is generally obtained by heating the hydrolyzable silane compound represented by the general formula (1) or a mixture of this with a hydrolyzable silane compound other than the general formula (1). it can. The hydrolyzable silane compound is hydrolyzed by heating to become a hydrolyzate, or the hydrolyzate undergoes a condensation reaction to produce component (A).

(1) Organic group R ¹
R ¹ in the general formula (1) is a non-hydrolyzable organic group having 1 to 12 carbon atoms and containing a fluorine atom. Here, the non-hydrolyzable means that it is a property that exists stably as it is under the condition that the hydrolyzable group X is hydrolyzed. Examples of such non-hydrolyzable organic groups include fluorinated alkyl groups and fluorinated aryl groups. Specific examples of the fluorinated alkyl group include a trifluoromethyl group, a trifluoropropyl group, a heptadecafluorodecyl group, a tridecafluorooctyl group, and a nonafluorohexyl group. Specific examples of the fluorinated aryl group include a pentafluorophenyl group.
Of these, C _n F _{2n + 1} C _m H _2m [m is an integer of 0 to 5, n is an integer of 1 to 12, and m + n is 1 to 12. A fluorinated alkyl group represented by the formula (1), having a large fluorine content such as a heptadecafluorodecyl group, a tridecafluorooctyl group, a nonafluorohexyl group, etc., and having a long chain is particularly preferable.
The subscript p in the general formula (1) is an integer of 1 or 2, but is preferably 1.

(3) Hydrolyzable group X
X in the general formula (1) is a hydrolyzable group. Here, the hydrolyzable group is usually a silanol group that is hydrolyzed by heating in a temperature range of 0 to 150 ° C. for 1 to 10 hours in the presence of a catalyst and excess water at 1 atm. Or a group capable of forming a siloxane condensate.
Here, examples of the catalyst include an acid catalyst and an alkali catalyst. Examples of the acid catalyst include monovalent or polyvalent organic acids, inorganic acids, Lewis acids, and the like. Specific examples of the organic acid include formic acid, acetic acid, oxalic acid and the like. Specific examples of the Lewis acid include metal compounds, inorganic salts such as Ti, Zr, Al, and B, alkoxides, and carboxylates. Specific examples of the alkali catalyst include alkali metal or alkaline earth metal hydroxides, amines, acidic salts, basic salts, and the like. The addition amount of the catalyst necessary for the hydrolysis is preferably 0.001 to 5%, more preferably 0.002 to 1% with respect to the total silane compound.

Specific examples of the hydrolyzable group X include a hydrogen atom, an alkoxy group having 1 to 12 carbon atoms, a halogen atom, an amino group, and an acyloxy group.
Here, preferred specific examples of the alkoxy group having 1 to 12 carbon atoms include methoxy group, ethoxy group, propoxy group, butoxy group, phenoxybenzyloxy group, methoxyethoxy group, acetoxyethoxy group, and 2- (meth) acryloxy. In addition to ethoxy group, 3- (meth) acryloxypropoxy group, 4- (meth) acryloxybutoxy group, etc., epoxy group-containing alkoxy groups such as glycidyloxy group, 2- (3,4-epoxycyclohexyl) ethoxy group, Examples thereof include oxetanyl group-containing alkoxy groups such as methyl oxetanyl methoxy group and ethyl oxetanyl methoxy group, and alkoxy groups having a 6-membered ring ether group such as oxacyclohexyloxy.

Preferred halogen atoms include fluorine, chlorine, bromine and iodine.
However, when using a hydrolyzable silane compound containing a halogen atom as the hydrolyzable group in this way, care must be taken not to reduce the storage stability of the composition. That is, although depending on the amount of hydrogen halide produced by hydrolysis, such hydrogen halide should be removed by operations such as neutralization and distillation so as not to adversely affect the storage stability of the composition. Is preferred.

(4) Specific examples of hydrolyzable silane compounds represented by general formula (1) Specific examples of hydrolyzable silane compounds represented by general formula (1) include trifluoromethyltrimethoxysilane and trifluoromethyl. Triethoxysilane, 3,3,3-trifluoropropyltrichlorosilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,4,4,5,5,5,6,6,6-nona Fluorohexyltrichlorosilane, 3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorodecyltrichlorosilane, 3,3,4,4,5,5 6,6,7,7,8,8,8-heptadecafluorodecyltrimethoxysilane, 3,3,4,4,5,5,6,6,7,7,8,8,8-heptadeca Fluorodecyltriethoxysilane, 3-F Data fluoro isopropoxyphenyl triethoxysilane, pentafluoro-phenylpropyl trimethoxysilane, pentafluorophenyl phenylpropyl trichlorosilane and the like. Among these, 3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorodecyltriethoxysilane and 3,3,4,4,5,5 6,6,7,7,8,8,8-heptadecafluorodecyltrimethoxysilane, 3,3,4,4,5,5,5,6,6,6-nonafluorohexyltrichlorosilane, etc. preferable.

(5) Other hydrolyzable silane compounds Other hydrolyzable silane compounds include tetrachlorosilane, tetraaminosilane, tetraacetoxysilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetraphenoxysilane, and tetrabenzyloxysilane. Silane compounds having four hydrolyzable groups such as trimethoxysilane and triethoxysilane; methyltrichlorosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriisopropoxy It has three hydrolyzable groups such as silane, ethyltributoxysilane, butyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, deuterated methyltrimethoxysilane, etc. Or a silane compound having two hydrolyzable groups such as dimethyldichlorosilane, dimethyldiaminosilane, dimethyldiacetoxysilane, dimethyldimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and dibutyldimethoxysilane. .

(6) Preparation of component (A)
The method for obtaining the component (A) by heating the hydrolyzable silane compound represented by the general formula (1) is not particularly limited as long as the silanol group content described later is not excessively or excessively reduced. The method which consists of the process of 1) -3) shown to can be mentioned. However, in the hydrolyzate of the hydrolyzable silane compound represented by the general formula (1), a partially unhydrolyzed hydrolyzable group may remain. In that case, the hydrolyzable silane compound and the hydrolyzate It becomes a mixture with things.

1) The hydrolyzable silane compound and acid catalyst represented by the general formula (1) are accommodated in a container equipped with a stirrer.
2) Next, an organic solvent is further accommodated in the container while adjusting the viscosity of the obtained solution to obtain a mixed solution.
3) After stirring the obtained mixed solution at a temperature not higher than the boiling point of the organic solvent or hydrolyzable silane compound in an air atmosphere, at 0 to 150 ° C. for 1 to 24 hours. Stir with heating. In addition, during heating and stirring, it is also preferable to concentrate the mixed solution by distillation or replace the organic solvent as necessary. Here, in order to adjust the refractive index of the final cured product, the curability of the composition, the viscosity, and the like, a hydrolyzable silane compound other than the hydrolyzable silane compound represented by the general formula (1) is mixed. Thus, a siloxane oligomer can also be prepared. In this case, after adding and mixing the hydrolyzable silane compound of general formula (1) and the other hydrolyzable silane compound in the step 1), the reaction can be carried out by heating.

  In the preparation process of component (A), silanol groups are generated. Depending on the preparation method, the amount of silanol groups is not within the range specified in the present invention, and the waveguide loss of the optical waveguide is increased or the core of the core by photolithography is increased. It may adversely affect patterning formation. For this reason, it is preferable that the preparation process of (A) component follows the said method.

(7) Preferred Embodiment of Component (A) The component (A) preferably has the structure of the following general formula (2).

［一般式（２）中、Ｒ^３は非加水分解性で炭素数が１〜１２のフッ素化アルキル基またはフッ素化アリール基である。］
（Ａ）成分が上記構造を有していると、本発明の放射線硬化型組成物から製造される光導波路の耐クラック性等の物性をより一層向上させることができる。
さらに、前記一般式（１）のＲ^１が、ＣＦ_３（ＣＦ_２）_ｎ（ＣＨ_２）_ｍ［ｍは０〜５の整数、ｎは１〜１１の整数であり、ｍ＋ｎは１〜１１である。］であることが好ましい。Ｒ^１がこのような構造であると、本発明の放射線硬化型組成物を用いてフォトリソグラフィー法により光導波路を製造する際のパターニング性、該光導波路の耐クラック性、および導波路損失等をより一層向上させることができる。
Ｒ^１が上記構造である場合において、（Ａ）成分はさらに、下記一般式（４）及び（５）からなる群のうち少なくとも一種以上の構造を有することが好ましい。

[In the general formula (2), R ³ is the number of carbon atoms in the nonhydrolyzable is 1-12 fluorinated alkyl group or fluorinated aryl group. ]
When (A) component has the said structure, physical properties, such as crack resistance of the optical waveguide manufactured from the radiation-curable composition of this invention can be improved further.
Further, the ^{R 1} of the general formula (1) _{is, CF 3 (CF 2) n} (CH 2) m [m is an integer of 0 to 5, n is an integer of 1 to 11, m + n is 1 to 11 is there. ] Is preferable. When R ¹ has such a structure, patterning properties when producing an optical waveguide by photolithography using the radiation curable composition of the present invention, crack resistance of the optical waveguide, waveguide loss, etc. This can be further improved.
In the case where R ¹ has the above structure, the component (A) preferably further has at least one structure selected from the group consisting of the following general formulas (4) and (5).

［一般式（４）又は（５）中、Ｒ^５はフェニル基、あるいはフッ素化フェニル基、Ｒ^６はフッ素原子を含んでいてもよい炭素数が１〜１２である非加水分解性の有機基であってＲ^５と同じでもよい。］
これらの一般式（４）または一般式（５）の構造を有する加水分解性化合物の具体例としては、上述の一般式（１）、または一般式（１）以外の加水分解性シラン化合物の具体例のうち、フェニル基またはフッ素化フェニル基を有する化合物が挙げられる。これらのうち、フェニルトリメトキシシラン、フェニルトリエトキシシラン、ペンタフルオロフェニルトリメトキシシラン等が特に好ましい。
（Ａ）成分が上記構造を有していると、本発明の放射線硬化型組成物を用いて形成される光導波路の耐熱性やパターニング性をより一層向上させることができる。

[In General Formula (4) or (5), R ⁵ is a phenyl group or a fluorinated phenyl group, and R ⁶ is a non-hydrolyzable organic group having 1 to 12 carbon atoms which may contain a fluorine atom. And may be the same as R ⁵ . ]
Specific examples of the hydrolyzable compound having the structure of the general formula (4) or the general formula (5) include specific examples of the hydrolyzable silane compounds other than the above general formula (1) or the general formula (1). Among the examples, compounds having a phenyl group or a fluorinated phenyl group can be mentioned. Of these, phenyltrimethoxysilane, phenyltriethoxysilane, pentafluorophenyltrimethoxysilane and the like are particularly preferable.
When the component (A) has the above structure, the heat resistance and patternability of the optical waveguide formed using the radiation curable composition of the present invention can be further improved.

[Component (B)]
The component (B) is a photoacid generator. By irradiating with radiation, the component (B) is decomposed and an acidic active substance that photocures the component (A) can be released.
Here, examples of the radiation include visible light, ultraviolet rays, infrared rays, X-rays, electron beams, α rays, and γ rays. However, it is preferable to use ultraviolet rays from the viewpoint of having a constant energy level, a high curing rate, and a relatively inexpensive and compact irradiation apparatus.

  Examples of the component (B) include an onium salt having a structure represented by the following general formula (6), a sulfonic acid derivative having a structure represented by the following general formula (7), and the like.

_{^{[R 7 a R 8 b R}} 9 c R 10 d W] + m [MZ m + n] -m (6)
[In General Formula (6), the cation is an onium ion, W is S, Se, Te, P, As, Sb, Bi, O, I, Br, Cl, or —N≡N, and R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are the same or different organic groups, a, b, c and d are each an integer of 0 to 3, and (a + b + c + d) is equal to the valence of W. M is a metal or metalloid constituting the central atom of the halide complex [MZ _{m + n} ], for example, B, P, As, Sb, Fe, Sn, Bi, Al, Ca, In, Ti, Zn, Sc, V, Cr, Mn, and Co. Z is, for example, a halogen atom or an aryl group such as F, Cl, Br, etc., m is the net charge of the halide complex ion, and n is the valence of M. ]

Q _s- [S (= O) ₂ -R ¹¹ ] _t (7)
[In the general formula (7), Q is a monovalent or divalent organic group, R ¹¹ is a monovalent organic group having 1 to 12 carbon atoms, the subscript s is 0 or 1, and the subscript t is 1 or 2. is there. ]

(1) Onium salt Specific examples of the anion [MZ _{m + n} ] in the general formula (6) include tetrafluoroborate (BF ₄ ⁻ ), hexafluorophosphate (PF ₆ ⁻ ), hexafluoroantimonate (SbF ₆ ⁻ ), Examples include hexafluoroarsenate (AsF ₆ ⁻ ), hexachloroantimonate (SbCl ₆ ⁻ ), tetraphenyl borate, tetrakis (trifluoromethylphenyl) borate, tetrakis (pentafluoromethylphenyl) borate and the like.
Further, instead of the anion _{[MZ m + n]} in the general formula (6), the general formula ^- it is also preferable to use the anion represented by _[MZ n OH]. Furthermore, perchlorate ion (ClO ₄ ⁻ ), trifluoromethane sulfonate ion (CF ₃ SO ₄ ⁻ ), fluorosulfonate ion (FSO ₄ ⁻ ), toluene sulfonate ion, trinitrobenzene sulfonate anion, trinitrotoluene sulfonate Onium salts having other anions such as anions can also be used.

［一般式（８）中、Ｒ^１２およびＲ^１３は、それぞれ独立して水素又はアルキル基、Ｒ^１４は水酸基または−ＯＲ^１５（但し、Ｒ^１５は１価の有機基である。）を示し、ａは４〜７の整数、ｂは１〜７の整数である。ナフタレン環への各置換基の結合位置は特に限定されない。］
［Ｒ^１６−Ｐｈ^１−Ｉ^＋−Ｐｈ^２−Ｒ^１７］［Ｙ⁻］ （９）
［一般式（９）中、Ｒ^１６およびＲ^１７は、それぞれ１価の有機基であり、同一でも異なっていてもよく、Ｒ^１６およびＲ^１７の少なくとも一方は、炭素数が４以上のアルキル基を有しており、Ｐｈ^１およびＰｈ^２はそれぞれ芳香族基であり、同一でも異なっていてもよく、Ｙ⁻は１価の陰イオンであり、周期律表３族、５族のフッ化物陰イオンもしくは、ＣｌＯ_４ ⁻、ＣＦ_３ＳＯ_３ ⁻から選ばれる陰イオンである。］ The onium salt is preferably an aromatic onium salt, particularly preferably a triarylsulfonium salt, a compound represented by the following general formula (8), a diaryl iodonium salt represented by the following general formula (9) or a triaryl iodonium. It is salt.

[In General Formula (8), R ¹² and R ¹³ each independently represent hydrogen or an alkyl group, R ¹⁴ represents a hydroxyl group or —OR ¹⁵ (where R ¹⁵ is a monovalent organic group), a is an integer of 4 to 7, and b is an integer of 1 to 7. The bonding position of each substituent to the naphthalene ring is not particularly limited. ]
^{[R 16 -Ph 1 -I + -Ph} 2 -R 17] [Y -] (9)
[In General Formula (9), R ¹⁶ and R ¹⁷ are each a monovalent organic group and may be the same or different, and at least one of R ¹⁶ and R ¹⁷ is an alkyl group having 4 or more carbon atoms. And Ph ¹ and Ph ² are each an aromatic group, which may be the same or different, Y ⁻ is a monovalent anion, and is a group 3 or group 5 fluoride anion in the periodic table. An ion or an anion selected from ClO ₄ ⁻ and CF ₃ SO ₃ ^— . ]

Examples of the compound represented by the general formula (8) include 4-hydroxy-1-naphthyltetrahydrothiophenium trifluoromethanesulfonate, 4-butoxy-1-naphthyltetrahydrothiophenium trifluoromethanesulfonate, 1- (4,7- And dihydroxy) -naphthyltetrahydrothiophenium trifluoromethanesulfonate, 1- (4,7-di-t-butoxy) -naphthyltetrahydrothiophenium trifluoromethanesulfonate, and the like.
Further, as the diaryl iodonium salt, specifically, (4-n-decyloxyphenyl) phenyl iodonium hexafluoroantimonate, [4- (2-hydroxy-n-tetradecyloxy) phenyl] phenyl iodonium hexafluoroantimonate [4- (2-hydroxy-n-tetradecyloxy) phenyl] phenyliodonium trifluorosulfonate, [4- (2-hydroxy-n-tetradecyloxy) phenyl] phenyliodonium hexafluorophosphate, [4- (2 -Hydroxy-n-tetradecyloxy) phenyl] phenyliodonium tetrakis (pentafluorophenyl) borate, bis (4-t-butylphenyl) iodonium hexafluoroantimonate, bis (4-t-butylphenyl) Iodonium hexafluorophosphate, bis (4-t-butylphenyl) iodonium trifluorosulfonate, bis (4-t-butylphenyl) iodonium tetrafluoroborate, bis (dodecylphenyl) iodonium hexafluoroantimonate, bis (dodecylphenyl) Examples thereof include one or a combination of two or more of iodonium tetrafluoroborate, bis (dodecylphenyl) iodonium hexafluorophosphate, bis (dodecylphenyl) iodonium trifluoromethylsulfonate, and the like.

(2) Sulfonic acid derivatives The sulfonic acid derivatives represented by the general formula (7) include disulfones, disulfonyldiazomethanes, disulfonylmethanes, sulfonylbenzoylmethanes, imidosulfonates, benzoinsulfonates, 1-oxy Examples include sulfonates of 2-hydroxy-3-propyl alcohol, pyrogallol trisulfonates, benzyl sulfonates, and the like.
Among these, imide sulfonates are preferable, and trifluoromethyl sulfonate derivatives are more preferable.

(B) Although the addition amount of a photo-acid generator is not restrict | limited in particular, It is 0.01-15 weight part normally with respect to 100 weight part of (A) component. When the addition amount of the photoacid generator is less than 0.1 parts by weight, the photocurability is lowered and a sufficient curing rate tends not to be obtained. On the other hand, when the addition amount of a photo-acid generator exceeds 15 weight part, there exists a tendency for the weather resistance and heat resistance of the hardened | cured material obtained to fall.
From the viewpoint of improving the balance between the photocurability and the weather resistance of the resulting cured product, the addition amount of the photoacid generator as the component (B) is 0 with respect to 100 parts by weight of the component (A). It is preferable to set the value within the range of 1 to 10 parts by weight.

[Component (C)]
The radiation curable composition of the present invention can improve the storage stability of the composition by blending (C) an organic solvent, and can impart an appropriate viscosity to an optical waveguide having a uniform thickness. Can be formed.

Examples of the organic solvent (C) include ether organic solvents, ester organic solvents, ketone organic solvents, hydrocarbon organic solvents, alcohol organic solvents, and the like. Usually, it is preferable to use an organic solvent having a boiling point under atmospheric pressure in the range of 50 to 200 ° C. and capable of uniformly dissolving each component.
Examples of such organic solvents include aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, monoalcohol solvents, polyhydric alcohol solvents, ketone solvents, ether solvents, ester solvents, nitrogen-containing solvents. A sulfur-containing solvent or the like can be used. These organic solvents are used singly or in combination of two or more.

Among these (C) organic solvents, alcohols and ketones are preferable. This is because the storage stability of the composition can be further improved.
More preferable organic solvents include at least one compound selected from the group consisting of propylene glycol monomethyl ether, ethyl lactate, methyl isobutyl ketone, methyl amyl ketone, toluene, xylene, and methanol.

  In addition, the type of (C) organic solvent is preferably selected in consideration of the coating method of the composition. For example, since a thin film having a uniform thickness can be easily obtained, it is preferable to use a spin coating method. Examples of the organic solvent used in this case include glycols such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether. Ethers; Ethylene glycol alkyl ether acetates such as ethyl cellosolve acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate; Esters such as ethyl lactate and ethyl 2-hydroxypropionate; Diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol ethyl Diethylene glycols such as methyl ether; methyl isobutyl ketone, 2-heptanone, cyclohexanone Preferred to use ketones such as methyl amyl ketone, particularly ethyl cellosolve acetate, propylene glycol methyl ether acetate, ethyl lactate, it is preferable to use methyl isobutyl ketone and methyl amyl ketone.

Component (C) is added in an amount of 1 to 300 parts by weight, preferably 2 to 200 parts by weight, per 100 parts by weight of component (A). If it is in the range of 1 to 300 parts by weight, the storage stability of the composition can be improved, an appropriate viscosity can be imparted, and an optical waveguide having a uniform thickness can be formed.

  In addition, although the addition method in particular of (C) organic solvent is not restrict | limited, For example, you may add when manufacturing (A) component and mix | blend (A) component and (B) component You may add when you do.

[Silanol group content in the composition]
The content of silanol groups in the bonding groups on all Si derived from the trifunctional hydrolyzable silane compound in the radiation curable composition of the present invention is 10 to 50% (preferably 20 to 40%). It is necessary to be. If it is out of this range, patterning of the desired shape cannot be obtained during alkali development, or the waveguide loss value may increase when an optical waveguide is formed.

[Other ingredients]
Furthermore, within the range that does not impair the object and effect of the present invention, an acid diffusion controller, a reactive diluent, a radical generator (photopolymerization initiator), a photosensitizer, a metal alkoxide, inorganic fine particles, a dehydrating agent, and a leveling agent. , Polymerization inhibitors, polymerization initiation assistants, wettability improvers, surfactants, plasticizers, UV absorbers, antioxidants, antistatic agents, silane coupling agents, polymer additives, and the like are also preferably added. .

(D) Acid Diffusion Control Agent The acid diffusion control agent of component (D) controls the diffusion of the acidic active substance generated from the photoacid generator by photoirradiation in the coating and suppresses the curing reaction in the non-irradiated region. It is defined as a compound having an action. However, in order to distinguish from a photoacid generator by definition, the acid diffusion control agent of component (D) is a compound that does not have an acid generation function.
By adding such an acid diffusion controller, the photocurable composition can be effectively cured and the pattern accuracy can be improved.

As a kind of (D) component acid-diffusion controlling agent, the nitrogen-containing organic compound whose basicity does not change with the exposure in a formation process or heat processing is preferable.
Examples of such nitrogen-containing organic compounds include compounds represented by the following general formula (10).
NR ¹⁸ R ¹⁹ R ²⁰ (10)
[In General Formula (10), R ¹⁸ , R ¹⁹ and R ²⁰ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group. To express. ]

Other nitrogen-containing organic compounds include diamino compounds having two nitrogen atoms in the same molecule, diamino polymers having three or more nitrogen atoms, amide group-containing compounds, urea compounds, nitrogen-containing heterocycles. A compound etc. can be mentioned.
Specific examples of the nitrogen-containing organic compound include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; di-n-butylamine, di-n -Dialkylamines such as pentylamine, di-n-hexylamine, di-n-heptylamine, di-n-octylamine, di-n-nonylamine, di-n-decylamine; triethylamine, tri-n-propylamine , Tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decylamine, etc. Amines; aniline, N-methylaniline, N, N-dimethylaniline, 2-methylaniline, - methylaniline, 4-methylaniline, 4-nitroaniline, diphenylamine, triphenylamine, aromatic amines such as 1-naphthylamine; can be mentioned ethanolamine, diethanolamine, alkanolamines such as triethanolamine and the like.
In addition, an acid diffusion control agent can also be used individually by 1 type, or can also be used in mixture of 2 or more types.

(D) It is preferable that the addition amount of an acid diffusion controller is a value within the range of 0.001 to 15 parts by weight with respect to 100 parts by weight of component (A).
The reason for this is that when the amount of the acid diffusion control agent added is less than 0.001 part by weight, the pattern shape and dimensional reproducibility of the optical waveguide may be lowered depending on the process conditions. It is because the photocurability of (A) component may fall when the addition amount of a control agent exceeds 15 weight part.
Therefore, the addition amount of the acid diffusion control agent is more preferably set to a value within the range of 0.001 to 10 parts by weight with respect to 100 parts by weight of the component (A), and the range of 0.005 to 5 parts by weight. More preferably, the value is within the range.

The radiation curable composition of the present invention can be used as a lower layer composition, a core composition and an upper layer composition, respectively, in order to form a lower clad layer, a core portion and an upper clad layer constituting an optical waveguide. it can.
In such a composition for the lower layer, the composition for the core, and the composition for the upper layer, the relationship between the refractive indexes of the respective parts finally obtained satisfies the conditions required for the optical waveguide. Different resin compositions can be used. However, it is more preferable that the lower layer composition and the upper layer composition are the same resin composition because the formation of the optical waveguide and the like becomes easier.

  Moreover, the radiation curable composition of this invention can form easily the optical waveguide which consists of a core part which has a different refractive index, and an upper and lower clad layer by selecting the kind of (A) component. Therefore, after selecting two or more types of resin compositions having a suitable difference in refractive index, for example, a resin composition capable of obtaining a high refractive index is used as the core composition, and more than that. It is preferable to use a resin composition having a low refractive index as the lower layer composition and the upper layer composition.

  Further, the viscosity of the radiation curable composition of the present invention is preferably 5 to 5,000 mPa · s, more preferably 10 to 1,000 mPa · s at 25 ° C. When the viscosity exceeds 5,000 mPa · s, it may be difficult to form a uniform coating film. The viscosity of the resin composition can be appropriately adjusted depending on the amount of the reactive diluent and the organic solvent.

Next, a method for forming an optical waveguide using the radiation curable composition of the present invention will be described. The method mainly includes a lower clad layer forming step, a core portion forming step, and an upper clad layer forming step. Hereinafter, it will be described in detail with reference to FIG.
In the following description, the radiation curable composition of the present invention is used for the lower clad layer 2, the core portion 4, and the upper clad layer 6, respectively. In that case, a known optical waveguide material such as quartz glass can be used for the other lower cladding layer 2 and upper cladding layer 6.

In the optical waveguide having the above configuration, the thicknesses of the lower cladding layer 2, the upper cladding layer 6 and the core portion 4 are not particularly limited. For example, the thickness of the lower cladding layer 2 is in the range of 3 to 50 μm. It is preferable that the thickness of the core portion 4 is 3 to 20 μm, and the thickness of the upper cladding layer 6 is 3 to 50 μm.
Further, the width of the core portion 4 in the direction perpendicular to the light guiding direction is not particularly limited, but preferably has a value in the range of 1 to 50 μm, for example.

In the present invention, the optical waveguide is formed through steps (a) to (e) as shown in FIG. That is, the lower clad layer 2, the core portion 4, and the upper clad layer 6 (not shown in FIG. 2, see FIG. 1) are all photocurable for forming an optical waveguide for forming those layers. It is preferable to form the composition by photocuring after coating.
In the following formation examples, the lower clad layer 2, the core portion 4 and the upper clad layer 6 are compositions for the lower layer which is a photocurable composition for forming an optical waveguide from which cured products having different refractive indexes after curing are obtained. It is assumed that it is formed from a product, a core composition, and an upper layer composition.

(1) Preparation of Substrate First, as shown in FIG. 2A, a substrate 1 having a flat surface is prepared. The type of the substrate 1 is not particularly limited. For example, a silicon substrate or a glass substrate can be used.

(2) Lower clad layer forming step In this step, the lower clad layer 2 is formed on the surface of the prepared substrate 1. Specifically, as shown in FIG. 2B, the lower layer composition is applied to the surface of the substrate 1 and dried or prebaked to form a lower layer thin film. Then, the lower clad layer 2 can be formed by curing the lower layer thin film by irradiating light.
The light used for forming the core layer and the clad layer is not particularly limited, but light in the ultraviolet to visible region of 200 to 450 nm, preferably light including ultraviolet light having a wavelength of 365 nm is usually used. Irradiation at wavelengths 200~450nm, the illuminance is 1~1000mW / cm ^2, irradiation amount 0.01~5000mJ / cm ^2, and preferably is carried out such that the 0.1~1000mJ / cm ^2, is exposed The

Here, visible light, ultraviolet rays, infrared rays, X-rays, α-rays, β-rays, γ-rays, and the like can be used as the type of light to be irradiated, but 200 is preferable from the industrial versatility of the light source. A wavelength including ultraviolet rays of ˜400 nm, particularly preferably 365 nm is preferable. As the irradiation device, for example, a lamp light source that simultaneously irradiates a wide area such as a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, or an excimer lamp, and a laser light source such as a pulse or continuous light source, or both Accordingly, a mirror, a lens, or an optical fiber that generates convergent light can be used.
In the case of forming an optical waveguide using convergent light, exposure can be performed so that the shape of the optical waveguide is obtained by moving either the convergent light or the irradiated object. Among these light sources, a light source with high ultraviolet intensity of 365 nm is preferable. For example, a high pressure mercury lamp is preferable as a lamp light source, and an argon laser is preferable as a laser light source.
In the step of forming the lower clad layer 2, it is preferable to irradiate the entire surface of the thin film with light and harden the whole.

  Here, as a method for applying the lower layer composition, a spin coating method, a dipping method, a spray method, a bar coating method, a roll coating method, a curtain coating method, a gravure printing method, a silk screen method, an ink jet method, or the like can be used. Can be used. Among these, it is more preferable to employ the spin coat method because a thin film for a lower layer having a uniform thickness can be obtained.

Moreover, in order to make the rheological characteristic of the composition for lower layers appropriately corresponding to the coating method, additives other than the surface tension reducing agent can be blended as necessary.
Moreover, it is preferable to pre-bake the thin film for lower layers which consists of a composition for lower layers at 50-200 degreeC after application | coating.
The coating method in the lower clad layer forming step, the rheological property improving method, and the like can be applied as they are in the core portion forming step and the upper clad layer forming step described later.

Further, after the exposure, it is preferable to further perform heat treatment (hereinafter referred to as “post-bake”) so that the entire surface of the coating film is sufficiently cured. This heating condition varies depending on the blending composition of the photocurable composition for forming an optical waveguide, the kind of additive, and the like, but is usually 30 to 400 ° C., preferably 50 to 300 ° C., for example, for 5 minutes to 72 hours. The heating time may be set.
Note that the light irradiation amount, type, irradiation apparatus, and the like in the lower clad layer forming step can be applied as they are in the core portion forming step and the upper clad layer forming step, which will be described later.

(3) Formation of core portion Next, as shown in FIG. 2 (c), a core composition is applied on the lower cladding layer 2 and dried or further pre-baked to form the core thin film 3. To do.
Thereafter, as shown in FIG. 2 (d), the upper surface of the core thin film 3 is irradiated with radiation 5 through a photomask 7 having a predetermined line pattern, for example, according to a predetermined pattern. preferable.
As a result, only the portion irradiated with the light is cured, so that other uncured portions are developed and removed with a developer so that the upper clad layer 2 is formed on the lower clad layer 2 as shown in FIG. The core portion 4 made of a patterned cured film can be formed.

Here, the method of irradiating light according to a predetermined pattern is not limited to a method using a photomask composed of a light transmission part and a non-transmission part, and examples thereof include the following methods a to c. .
a. A method using electro-optical means for forming a mask image composed of a light transmission region and a non-transmission region according to a predetermined pattern, using the same principle as that of a liquid crystal display device.
b. A method of irradiating light through an optical fiber corresponding to a predetermined pattern in the light guide member using a light guide member formed by bundling a large number of optical fibers.
c. A method of irradiating a photocurable composition while scanning convergent light obtained by a laser beam or a condensing optical system such as a lens or a mirror.

  In addition, it is preferable to perform a heat treatment (hereinafter referred to as “PEB”) in order to promote curing of the exposed portion after exposure. The heating condition varies depending on the blending composition of the photocurable composition for forming an optical waveguide, the type of additive, and the like, but is usually 30 to 200 ° C, preferably 50 to 150 ° C.

On the other hand, the shape of the core portion can be made semicircular simply by leaving the coating film made of the photocurable composition for forming an optical waveguide at room temperature for 1 to 10 hours before exposure (and therefore. When it is desired to obtain a semicircular core portion, it is preferable to leave it at room temperature for several hours before exposure.
Thus, the thin film which has been subjected to pattern exposure according to a predetermined pattern and selectively cured can be developed by utilizing the difference in solubility between the cured portion and the uncured portion. Therefore, after pattern exposure, while removing an uncured portion and leaving a cured portion, a core portion can be formed as a result.

Here, as the developer, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, Ethanolamine, N-methylethanolamine, N, N-dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, choline, pyrrole, piperidine, 1,8-diazabicyclo [ 5.4.0] -7-undecene, basic substance such as 1,5-diazabicyclo [4.3.0] -5-nonane and water, methanol, ethanol, propyl alcohol, butanol, Kutanoru, propylene glycol monomethyl ether, propylene glycol monoethyl ether, N- methylpyrrolidone, formamide, N, N- dimethylformamide, N, N- dimethylacetamide can be used a solution diluted with a solvent such as.
The concentration of the basic substance in the developer is usually 0.05 to 25% by weight, preferably 0.1 to 3.0% by weight.

The development time is usually 30 to 600 seconds. As a developing method, a known method such as a liquid piling method, a dipping method, or a shower developing method can be employed.
When an organic solvent is used as the developer, it is directly air-dried. When an alkaline aqueous solution is used, it is washed with running water for 30 to 90 seconds and then air-dried with compressed air or compressed nitrogen. By removing moisture on the surface, a patterned film can be formed.

Next, in order to further cure the patterning portion, a post-baking process is performed, for example, at a temperature of 30 to 400 ° C. for 5 to 600 minutes with a heating device such as a hot plate or an oven, whereby a cured core portion is formed. .
In addition, it is preferable to use aminopolysiloxane with higher amino group content for the composition for cores than the composition for lower layers or the composition for upper layers.

  By configuring in this way, the pattern accuracy of the core portion can be further improved, while the lower layer composition and the upper layer composition can provide excellent storage stability and can be used with a relatively small radiation dose. Can be cured sufficiently.

(4) Formation of upper clad layer Next, the upper layer composition is applied to the surface of the lower clad layer 2 with the core portion 4 formed above, and dried or prebaked to form an upper layer thin film. By applying light to the upper thin film and curing it, the upper clad layer 6 can be formed as shown in FIG.
The upper clad layer 6 obtained by radiation irradiation is preferably subjected to the above-described post-baking as necessary. By post-baking, an upper cladding layer having excellent hardness and heat resistance can be obtained.

Further, in the optical waveguide, the refractive index value of the core portion 4 needs to be larger than the refractive indexes of the lower cladding layer 2 and the upper cladding layer 6, but in order to obtain better waveguide characteristics. For the light having a wavelength of 1300 to 1600 nm, the refractive index of the core portion 4 is set to a value within the range of 1.450 to 1.650, and the refractive indexes of the lower cladding layer 2 and the upper cladding layer 6 are set to 1. A value in the range of 400 to 1.648 is preferable.
The refractive index of the core portion 4 is preferably determined in consideration of the refractive index values of the upper and lower cladding layers 2 and 6, and is 0.002 to the refractive index value of the upper and lower cladding layers 2 and 6. More preferably, the value is 0.5 larger.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Preparation of component (A)]
[Synthesis Example 1]
In a flask equipped with a stirrer and a reflux tube, phenyltrimethoxysilane (30.79 g), 3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorodecyl Triethoxysilane (22.64 g), tetraethoxysilane (4.62 g), 1-methoxy-2-propanol (29.93 g), and oxalic acid (0.04 g) were added and stirred, and then the temperature of the solution was adjusted. Heated to 60 ° C. Then, distilled water (11.98 g) was added dropwise, and after completion of the addition, the solution was stirred at 120 ° C. for 6 hours. And the 1-methoxy-2-propanol solution of (A) component which finally adjusted solid content to 65 weight% was obtained. This is designated as “siloxane oligomer solution 1”.

[Synthesis Example 2]
In a flask equipped with a stirrer and a reflux tube, phenyltrimethoxysilane (30.56 g), 3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorodecyl Triethoxysilane (18.15 g), tetraethoxysilane (9.88 g), methyl-n-amyl ketone (27.72 g), and oxalic acid (0.04 g) were added and stirred, and the temperature of the solution was adjusted to 60 ° C. Heated to. Then, distilled water (13.66 g) was added dropwise, and after completion of the addition, the solution was stirred at 120 ° C. for 6 hours. And the methyl- n-amyl ketone solution of (A) component which finally adjusted solid content to 70 weight% was obtained. This is designated as “siloxane oligomer solution 2”.

[Synthesis Example 3]
In a flask equipped with a stirrer and a reflux tube, methyltrimethoxysilane (2.97 g), phenyltrimethoxysilane (29.01 g), 3,3,4,4,5,5,6,6,7,7, 8,8,8-heptadecafluorodecyltriethoxysilane (25.64 g), 1-methoxy-2-propanol (31.00 g), and oxalic acid (0.04 g) were added and stirred, then the temperature of the solution Was heated to 60 ° C. Then, distilled water (11.35 g) was added dropwise, and after completion of the addition, the solution was stirred at 120 ° C. for 6 hours. And the 1-methoxy-2-propanol solution of (A) component which finally adjusted solid content to 70 weight% was obtained. This is designated as “siloxane oligomer solution 3”.

[Comparative Synthesis Example 1]
In a flask equipped with a stirrer and a reflux tube, phenyltrimethoxysilane (30.79 g), 3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorodecyl Triethoxysilane (22.64 g), tetraethoxysilane (4.62 g), 1-methoxy-2-propanol (29.93 g), and oxalic acid (0.04 g) were added and stirred, and then the temperature of the solution was adjusted. Heated to 60 ° C. Then, distilled water (11.98 g) was added dropwise, and after completion of the addition, the solution was stirred at 120 ° C. for 6 hours. Thereafter, 1-methoxy-2-propanol was removed, and the resulting viscous liquid was further vacuum dried. This is designated as “siloxane oligomer 4”.

[Comparative Synthesis Example 2]
Pentafluorophenylethyltrichlorosilane (236.9 g) and (3,3,3-trifluoropropyl) trichlorosilane (231.5 g) are dissolved in 1 liter of dehydrated tetrahydrofuran, and water (92.9 g) is added thereto. The solution was slowly added dropwise so as not to raise the liquid temperature. Subsequently, sodium hydrogen carbonate (433.4 g) was added thereto while stirring the reaction solution. After the generation of carbon dioxide gas was completed, stirring was continued for another hour. Next, the reaction solution was filtered, and the tetrahydrofuran in the filtrate was distilled off with a rotary evaporator. As a result, a colorless transparent and viscous liquid was obtained. Further, this liquid was vacuum-dried to obtain “siloxane oligomer 5”.

[Comparative Synthesis Example 3]
In a flask equipped with a stirrer and a reflux tube, methyltrimethoxysilane (32.27 g), phenyltrimethoxysilane (24.41 g), 1-methoxy-2-propanol (23.85 g), and oxalic acid (0.03 g) ) Was added and stirred, and then the temperature of the solution was heated to 60 ° C. Then, distilled water (19.44 g) was added dropwise, and after completion of the addition, the solution was stirred at 120 ° C. for 6 hours. And the 1-methoxy-2-propanol solution which finally adjusted solid content to 70 weight% was obtained. This is designated as “siloxane oligomer solution 6”.

[Comparative Synthesis Example 4]
In a flask equipped with a stirrer and a reflux tube, a copolymer of methyl methacrylate and 3-methacryloxypropyltrimethoxysilane (solid content concentration: 27% by weight, diluted with methoxypropanol) (28.16 g), methyltrimethoxysilane ( 36.42 g), phenyltrimethoxysilane (20.37 g), and oxalic acid (0.04 g) were added and stirred, and then the temperature of the solution was heated to 60 ° C. Then, distilled water (15.01 g) was added dropwise, and after completion of the addition, the solution was stirred at 60 ° C. for 6 hours. And the 1-methoxy-2-propanol solution which finally adjusted solid content to 70 weight% was obtained. This is designated as “siloxane oligomer solution 7”.

[Preparation of radiation curable composition]
To 92.56 g of siloxane oligomer solution 1 (solid content and organic solvent), 0.32 g of 1- (4,7-di-t-butoxy) -naphthyltetrahydrothiophenium trifluoromethanesulfonate as a photoacid generator, By adding 0.03 g of n-octylamine and 7.09 g of 1-methoxy-2-propanol and mixing uniformly, “Composition 1” having a solid content concentration adjusted to 65% by weight was obtained.

  Hereinafter, in the same manner as “Composition 1”, “Composition 2” to “Composition 8” were prepared as shown in Table 1.

[Example 1]
The composition 3 was applied onto the surface of the silicon substrate with a spin coater, dried at 120 ° C. for 10 minutes, and then irradiated with ultraviolet rays having a wavelength of 365 nm and an illuminance of 6 mW / cm ² for 3 minutes with an exposure machine (Canon photo aligner). . Furthermore, by heating at 200 ° C. for 1 hour, a lower cladding layer having a thickness of 9 μm was formed. The refractive index of light having a wavelength of 1550 nm in this lower cladding layer was 1.439.
Next, the composition 1 was applied onto the lower clad layer with a spin coater, dried at 100 ° C. for 5 minutes, and then using a photomask engraved with an optical waveguide pattern having a width of 9 μm, a wavelength of 365 nm and an illuminance of 6 mW / cm ^2. The exposure was performed by irradiating the ultraviolet rays of 1 min. Thereafter, the substrate was heated at 100 ° C. for 1 minute, and then immersed in a developer composed of a 5% tetramethylammonium hydroxide (TMAH) aqueous solution to dissolve unexposed portions and washed with water. Then, after irradiating with ultraviolet rays for 3 minutes, a core portion having a thickness of 9 μm was formed by heating at 200 ° C. for 1 hour. The refractive index of light having a wavelength of 1550 nm in the obtained core portion was 1.445.
Further, the radiation curable composition 3 was applied to the upper surface of the lower clad layer having the core portion with a spin coater, dried at 120 ° C. for 10 minutes, and then irradiated with ultraviolet rays having a wavelength of 365 nm and an illuminance of 6 mW / cm ² for 10 minutes. did. Furthermore, by heating at 250 ° C. for 1 hour, an upper cladding layer having a thickness of 9 μm was formed, thereby forming an optical waveguide. The refractive index of light having a wavelength of 1550 nm in the formed upper clad layer was 1.439.

  For Example 2 and Comparative Examples 1, 2, and 3, optical waveguides were produced and evaluated in the same manner as Example 1. The evaluation results are shown in Table 2.

[Silanol content measurement]
Each composition was diluted with deuterated chloroform as an NMR measurement solvent, and the silanol content was measured by Si-NMR. Specifically, a plurality of silane components having different substituents and bonding groups appearing at −120 ppm to −60 ppm were peak-separated by curve fitting, and the mol% of each component was calculated from the peak area ratio. By multiplying the number of silanol groups in each of the obtained components, the ratio (%) to the bonding groups on the total Si was calculated.
An example calculation is shown below.
Mole% Number of silanol groups Peak 1: R—Si (OH) ₃ a 3
Peak 2: R—Si (OH) ₂ (OSi) b 2
Peak 3: R—Si (OH) (OSi) ₂ c 1
Peak 4: R—Si (OSi) ₃ d 0

Silanol content in all Si bonding groups (%)
= (3a + 2b + c) × 100 / [4 × (a + b + c + d)]

[Patternability]
The produced waveguide was cleaved, and the core shape (width and height) was measured with an optical microscope. The design value (width 9 μm, height 9 μm) is within the range of design value ± 0.5 μm, “o”, otherwise the shape is rectangular or trapezoidal, or the core could not be patterned The case was set as “x”.
[Waveguide loss]
When light having a wavelength of 1310 nm or 1550 nm was incident from one end of the waveguide, the loss [dB] was measured with a power meter of a light meter (Anritsu MT9810A). The waveguide loss [dB / cm] was obtained by cutting the waveguide by cleaving, measuring the loss at each length, plotting the loss against the length, and calculating from the slope. (Cutback method).

[Interface peeling]
The end face obtained by cleaving the produced waveguide is observed with a scanning electron microscope (SEM), and the substrate / lower clad layer, lower clad layer / core portion, core portion / upper clad layer, and lower clad layer / upper clad layer are observed. The presence or absence of peeling was determined. Furthermore, the presence or absence of peeling on the core line was observed with an optical microscope from above the waveguide. In either case, the case where no peeling was observed was indicated as “◯”, and the case where peeling was observed in any case was indicated as “x”.
[Crack resistance]
The obtained waveguide was heated at 300 ° C. for 1 hour and naturally cooled, and the presence or absence of cracks in the entire waveguide was observed with an optical microscope. The case where it was confirmed in any of the clads was designated as “x”.
[Long-term reliability]
The obtained optical waveguide is allowed to stand for 2000 hours under conditions of a temperature of 85 ° C. and a relative humidity of 85%, and then left for 24 hours at a temperature of 25 ° C. and a relative humidity of 50%. The transmission loss is measured, and the waveguide loss is calculated. did. The case where the waveguide loss is 0.5 dB / cm or less at both wavelengths of 1310 nm and 1550 nm is “◯”, and the others are “X”.

It is sectional drawing which shows an example of the optical waveguide of this invention typically. It is a flowchart which shows an example of the formation method of the optical waveguide of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower clad layer 3 Core thin film 4 Core portion 5 Radiation 6 Upper clad layer 7 Photomask

Claims (9)

The following components (A) and (B):
(A) at least one or more selected from the group consisting of a hydrolyzate of a hydrolyzable silane compound represented by the following general formula (1) and a condensate of the hydrolyzate;
(R ¹ ) Si (X) ₃ (1)
[In the general formula (1), R ¹ is a fluorinated alkyl group or fluorinated aryl group having a carbon number in the nonhydrolyzable is 1 to 12, X is a hydrolyzable group. ]
And (B) a radiation curable composition containing a photoacid generator,
The optical waveguide characterized in that the content of silanol (Si-OH) groups in the bonding groups on all Si derived from the trifunctional hydrolyzable silane compound in the composition is 10 to 50%. Radiation curable composition for forming . The radiation curable composition according to claim 1, wherein the component (A) has a structure represented by the following general formula (2).

[In the general formula (2), R ³ is the number of carbon atoms in the nonhydrolyzable is 1-12 fluorinated alkyl group or fluorinated aryl group. ] R ¹ in the formula (1) is CF ₃ (CF ₂ ) _n (CH ₂ ) _m [m is an integer of 0 to 5, n is an integer of 1 to 11, and m + n is 1 to 11. The radiation curable composition according to claim 1 or 2 . The radiation curable composition according to claim 3, wherein the component (A) further has at least one structure selected from the group consisting of the following general formulas (4) and (5).

[In General Formulas (4) and (5), R ⁵ is a phenyl group or a fluorinated phenyl group, and R ⁶ is a non-hydrolyzable organic group having 1 to 12 carbon atoms which may contain a fluorine atom. It may be the same as R ⁵ . ]   The radiation curable composition according to any one of claims 1 to 4, wherein an addition amount of the (B) photoacid generator is 0.01 to 15 parts by weight with respect to 100 parts by weight of the component (A). A lower clad layer, a core portion formed in a part of a region on the lower clad layer, and an upper clad layer formed on the lower clad layer so as to cover the core portion, and A thickness of the lower clad layer and the upper clad layer is 3 to 50 μm, and a thickness of the core portion is 3 to 20 μm, and is selected from the lower clad layer, the core portion, and the upper clad layer. The radiation curable composition according to any one of claims 1 to 5, for forming at least one of the above. An optical device comprising a lower clad layer, a core portion formed in a part of a region on the lower clad layer, and an upper clad layer formed on the lower clad layer so as to cover the core portion In the method of forming the waveguide,
At least one or more selected from the lower clad layer, the core portion, and the upper clad layer is applied using the radiation curable composition according to any one of claims 1 to 6 as a material. And forming an optical waveguide by irradiation with radiation. An optical device comprising a lower clad layer, a core portion formed in a part of a region on the lower clad layer, and an upper clad layer formed on the lower clad layer so as to cover the core portion In the waveguide,
The light beam, wherein at least one selected from the lower clad layer, the core portion, and the upper clad layer is made of the radiation curable composition according to any one of claims 1 to 6. Waveguide. The optical waveguide according to claim 8, wherein the thickness of the lower cladding layer and the upper cladding layer is 3 to 50 µm, and the thickness of the core portion is 3 to 20 µm.

Images