JP5749068B2 - Manufacturing method of optical waveguide having optical path conversion function - Google Patents

Description

  The present invention relates to a method for manufacturing an optical waveguide having an optical path conversion function used in optical communication, optical information processing, and the like.

Optical waveguides are incorporated in optical devices such as optical waveguide devices, optical integrated circuits, and optical wiring boards, and are widely used in fields such as optical communication and optical information processing. Development of polymer optical waveguides using these polymer resin materials has been actively conducted.
This is because the polymer material can be easily formed into a thin film by a spin coating method, a dip method, etc., and it is easy to produce a large-area optical component. It is possible to produce optical waveguides on substrates that are difficult to heat-treat at high temperatures, such as substrates and plastic substrates, and to produce flexible optical waveguides that take advantage of the flexibility and toughness of polymers. (For example, refer patent document 1).

  A surface emitting laser (VCSEL) is attracting attention as a light source for various optical communication including optical interconnection from the viewpoint of cost and performance, but the laser light from the surface emitting laser is perpendicular to the substrate surface. Since the light is emitted, in order to make it incident on the optical waveguide arranged horizontally with respect to the substrate surface, an optical path change of about 90 ° is required.

  Examples of the optical path changing method include a method using an optical path changing element. When an optical device is manufactured, the optical communication light source, the optical waveguide, and the optical path changing element must be accurately positioned and bonded. Since it is complicated, a method of providing a light conversion mirror surface on the optical waveguide itself has been proposed.

  As a method of providing the light conversion mirror surface on the optical waveguide itself, for example, a method in which a ground surface generated by cutting with a blade having an inclination angle is used as an optical path conversion mirror surface (for example, see Patent Document 2). A processing method by laser ablation such as a method in which an oblique through hole is provided in a waveguide plate and the wall surface of the through hole is an optical path conversion mirror surface (see, for example, Patent Document 3), and an inclined surface is formed in a lower cladding portion by press molding. For example, a method of forming an optical path conversion mirror surface (see, for example, Patent Document 4) may be used.

JP-A-2005-128302 Japanese Patent Laid-Open No. 10-300961 JP 2000-347052 A JP 2003-57466 A

However, in the method using a blade as described in Patent Document 1, grooves other than necessary portions are formed, or conditions for producing a low-loss mirror greatly depend on cutting conditions and materials. There is a problem that the optical circuit board is difficult to be miniaturized and densified.
Moreover, in the processing method by laser ablation as described in Patent Document 2, there is a limit to the material that can form a smooth processed surface, and the wall surface damage due to the removed material during processing occurs, resulting in a smooth surface. There was a problem that it was difficult to ensure.
In any of the methods described in Patent Documents 2 to 4, since the optical path conversion mirror surface is formed after the optical waveguide is manufactured, an optical waveguide having an optical path conversion function can be directly formed on the substrate. There was a problem that the process was complicated.
For this reason, there has been a demand for a manufacturing method capable of directly forming an optical waveguide capable of fine processing, having high surface accuracy, and having an optical path conversion function on a substrate in a simple process.

On the other hand, when a polymer optical waveguide is manufactured using a positive photosensitive resin, after irradiation with patterned light, unnecessary portions are dissolved and removed using a developer to form a pattern.
A positive photosensitive resin is hardly soluble in a developer in an initial state, but exposure to energy rays such as ultraviolet rays improves the solubility in the developer. Patterning is performed using the difference in dissolution rate in the developer with the exposed portion.
In this development step, it is known that a phenomenon called “film reduction” occurs in which the surface of the pattern and the side surface of the pattern are dissolved by long contact with the developer.

  For example, when a pattern is formed by photolithography using a positive photosensitive resin, a process of applying a positive photosensitive resin diluted with a solvent or the like to a target material (application process), positive photosensitive A step of irradiating the resin layer with patterned light to improve the solubility of the irradiated portion (exposed portion) in the developer (exposure step), and removing the exposed portion by dissolving with the developer. A pattern is formed by the process of leaving the pattern of the exposed part (developing process) and the process of curing the remaining non-exposed part (curing process).

Since the positive photosensitive resin is hardly soluble but not insoluble in the developer, in the patterning development process using the layer of the positive photosensitive resin, even in the non-exposed part, although not as much as the exposed part, Dissolution by the developer occurs gradually.
Such a phenomenon that the non-exposed part dissolves in the development process is called “film reduction”. However, the dissolution of the non-exposed part is not only the upper surface of the non-exposed part but also the removal of the exposed part. It also occurs on the side of the unexposed part exposed by.
For this reason, not only the thickness of the non-exposed portion after development becomes thinner than before development, but also the upper portion of the non-exposed portion after development becomes narrower than the lower portion.

“Film reduction” is an obstacle to the formation of fine patterns in the field of photoresist, so development of resin compositions with little “film reduction” and examination of development methods are being actively conducted. There is no known pattern formation method that positively utilizes “film reduction”.
In the production of an optical waveguide using a photoresist, the core part is often produced by pattern formation, and the clad part is produced by pattern formation.

  Accordingly, an object of the present invention is to provide a manufacturing method capable of directly forming an optical waveguide having an optical path conversion function directly on a substrate in a simple process, capable of fine processing, having high surface accuracy, and an optical device manufactured by the manufacturing method. It is to provide a waveguide.

  As a result of intensive studies to solve the above problems, the present inventor does not form the optical path conversion mirror surface after manufacturing the optical waveguide, but forms the optical conversion mirror surface when manufacturing the optical waveguide. If possible, an optical waveguide having an optical path conversion function can be directly manufactured on a substrate in a simple process and in a large amount, that is, a polymer optical waveguide is manufactured using a positive photosensitive resin. In this case, if a positive photosensitive resin layer is formed on the substrate and the optical path conversion mirror surface of the optical waveguide can be formed in the pattern development process, a large number of optical path conversion mirror surfaces can be formed at a low cost by using an inexpensive method. I came up with the idea of becoming.

  As a result of further investigation based on this idea, the present inventor has developed a development process, which has conventionally been an obstacle to forming a fine pattern when the clad portion is formed of a positive photosensitive resin. The present inventors have found that the inclined surface of the side surface of the pattern formed by the “film reduction” generated in FIG.

  That is, according to the present invention, in an optical waveguide manufacturing method in which a clad portion is formed of a positive photosensitive resin, an inclined surface formed by film reduction in the developing process of the positive photosensitive resin is used as an optical path conversion mirror surface. The present invention provides a method for manufacturing an optical waveguide having an optical path conversion function.

  Further, the present invention provides a light guide having an optical path conversion function in which a clad portion is formed of a positive photosensitive resin, and an inclined surface formed by film reduction in the developing process of the positive photosensitive resin is used as an optical path conversion mirror surface. A waveguide is provided.

  According to the present invention, an optical waveguide having an optical path conversion function can be manufactured directly on a substrate by a simple process.

FIG. 1A is a schematic view showing that a positive photosensitive resin layer for forming a cladding portion is formed on a substrate. FIG. 1B is a schematic view showing that the clad portion is formed by curing the layer of the positive photosensitive resin for forming the clad portion. FIG. 1C is a schematic view showing that a layer of a positive photosensitive resin for forming a cladding part is further formed on the cladding part. FIG. 1D is a schematic view showing that the exposure to the developer in the exposed portion of the positive photosensitive resin layer for forming a cladding portion is improved by exposure using a pattern mask. FIGS. 1A to 1D are cross-sectional views of central portions of FIGS. 1A to 1D, respectively. FIG. 2E shows that the exposed portion dissolves in the developer and the non-exposed portion gradually dissolves, and an inclined surface (optical path conversion mirror surface) due to “film reduction” is being formed in the non-exposed portion. FIG. FIG. 2F is a schematic diagram showing that the dissolution of the exposed portion has progressed and the inclined surface of the non-exposed portion has reached the cladding portion. FIG. 2G is a schematic view showing that a non-exposed portion of the positive photosensitive resin layer for forming a cladding portion is cured to form a cladding portion. 2 (e ') to (g') are cross-sectional views of the central portion of FIGS. 2 (e) to (g), respectively. FIG. 3H is a schematic view showing that a negative photosensitive resin layer for forming a core part is formed on the clad part. FIG. 3 (i) shows that the exposed part of the negative photosensitive resin layer for forming the core part is cured by the exposure using the pattern mask and becomes insoluble in the developer (the core part is formed). It is the schematic which shows that. FIG. 3J is a schematic view showing that the non-exposed portion of the core-forming negative photosensitive resin layer is dissolved in the developer and the exposed portion (core portion) remains. FIG. 3K is a schematic view showing that a layer of a positive photosensitive resin for forming a clad portion is formed on the core portion. 3 (h ') to 3 (k') are cross-sectional views of the central portions of FIGS. 3 (h) to 3 (k), respectively. In FIG. 4 (l), the exposure to the developer of the positive photosensitive resin layer for forming the cladding portion on the inclined surface is improved by the exposure using the pattern mask for securing the optical path of the optical waveguide. It is the schematic which shows this. FIG. 4 (m) is a schematic view showing that a cavity portion serving as an optical path is formed by dissolving the clad portion forming positive photosensitive resin layer on the inclined surface in a developing solution. FIG. 4 (n) is a schematic view showing that the clad portion forming positive photosensitive resin layer is cured and a clad portion is formed on the core portion. FIG. 4 (o) is a schematic view showing that a layer of a negative photosensitive resin for forming a core part is formed in the hollow part serving as the optical path. FIG. 4 (p) is a schematic view showing that the core part forming negative photosensitive resin layer is cured and a core part is formed in the hollow part. 4 (l ′) to (p ′) are cross-sectional views of the central portion of FIGS. 4 (l) to (p), respectively. FIG. 5A is a schematic diagram showing the traveling direction of light in an optical waveguide having two optical path conversion mirror surfaces, and FIG. 5B shows the traveling direction of light in an optical waveguide having one optical path conversion mirror surface. FIG.

Hereinafter, the present invention will be described in detail based on preferred embodiments.
An optical waveguide to which the manufacturing method of the present invention is applied is obtained by surrounding a part or all of a core-shaped core part serving as an optical path with a clad part, and the core part is usually in the form of a sheet or a plate. Optical waveguides are classified into slab type, embedded type, semi-embedded type, ridge type, etc., depending on the structure of the core part and the cladding part, but the optical waveguide manufacturing method of the present invention can be applied to optical waveguides of any structure. Is possible.
Hereinafter, the embedded optical waveguide in which the method for manufacturing an optical waveguide of the present invention is preferably used will be described, but the present invention is not limited to the embedded optical waveguide.

In the optical waveguide manufacturing method of the present invention, the “film reduction” for forming the inclined surface that becomes the optical path conversion mirror surface of the optical waveguide is as described in the section “Problems to be solved by the invention” in the present specification. In the development process of the positive photosensitive resin, it means a phenomenon that the non-exposed portion is dissolved by the non-exposed portion being in contact with the developer for a long time.
Such dissolution occurs not only on the upper surface of the non-exposed portion, but also on the side surface of the non-exposed portion exposed by dissolution of the exposed portion.
For this reason, the width of the upper part of the non-exposed part is narrower than that of the lower part, the side surface of the non-exposed part is not perpendicular to the upper surface or the side surface, The inclination is such that the angle formed is an acute angle.
The present invention utilizes the inclination of the side surface of such an unexposed portion formed during development for optical path conversion of the optical waveguide. More specifically, the optical waveguide in which the cladding portion is formed of a positive photosensitive resin is used. In the manufacturing method, an inclined surface formed by film reduction in the developing process of the positive photosensitive resin is used as an optical path conversion mirror surface.

  The angle of the inclined surface serving as the optical path conversion mirror surface is not particularly limited, but since the optical path is preferably converted to 90 °, the angle formed between the side surface and the bottom surface of the non-exposed portion is 40 to 50 ° or non- The angle formed between the side surface and the top surface of the exposed portion is preferably 130 to 140 °, the angle formed between the side surface and the bottom surface is 43 to 47 °, or the angle formed between the side surface and the top surface is 133 to 137 °. Is more preferable, and the angle formed by the side surface and the bottom surface is 44 to 46 °, or the angle formed by the side surface and the top surface is most preferably 134 to 136 °.

  Hereinafter, a method for manufacturing an optical waveguide having an optical path conversion function according to the present invention will be described in detail with reference to the schematic diagrams of FIGS. 1 (a) to 4 (p) and FIGS. Explained. 1 (a) to 4 (p) are schematic views showing the manufacturing process of the optical waveguide of the present invention, and FIGS. 1 (a ′) to 4 (p ′) are respectively FIGS. It is sectional drawing of the center part of FIG.4 (p).

  FIGS. 1 (a) and (a ') to FIGS. 2 (g) and (g') show steps until an inclined surface is formed in the cladding portion 3 of the optical waveguide. As shown in FIGS. 1 (a) and (a '), a positive photosensitive resin for forming a cladding portion is applied on a substrate 1, and dried by heating if necessary, so that a positive photosensitive resin for forming a cladding portion is obtained. Layer 2 is formed. The clad portion forming positive photosensitive resin layer 2 is cured by a conventional method to form a clad portion 3 (lower clad layer) as shown in FIGS. In order to form an inclined surface, as shown in FIGS. 1C and 1C ′, a positive photosensitive resin for forming the cladding portion is further applied on the cladding portion 3, and heat drying is performed as necessary. Thus, the positive photosensitive resin layer 2 for forming the cladding portion is formed.

  In order to form a groove for forming the core portion, as shown in FIGS. 1D and 1D ′, the layer 5 of the positive photosensitive resin for forming the cladding portion is irradiated with ultraviolet rays 5 through the pattern mask 4. And improving the solubility in the developer of the exposed portion of the positive photosensitive resin layer 2 for forming the cladding portion (the positive photosensitive resin layer 6 for forming the cladding portion having improved solubility in the developer due to the exposure). ). Thereafter, when the exposed portion is dissolved with a developing solution, not only the exposed portion having improved solubility in the developing solution, but also the non-exposed portion exposed by dissolution of the exposed portion as shown in FIGS. 2 (e) and (e ′). Dissolution gradually occurs on the side surface of the portion, and an inclined surface starts to be formed on the side surface of the non-exposed portion by “film reduction”. As shown in FIGS. 2 (f) and (f ′), this inclined surface is The clad portion 3 is reached, and a groove having an inclined surface is formed in the clad portion forming positive photosensitive resin layer 2. The clad portion forming positive photosensitive resin layer 2 is cured by a conventional method to form a clad portion 3 having a groove having an inclined surface as shown in FIGS. 2 (g) and (g ′). .

  3 (h) and (h ') to FIGS. 3 (j) and (j') show steps until the core portion 8 of the optical waveguide and the optical path conversion mirror surface 9 are formed. In the production method of the present invention, the resin for forming the core portion may be either a positive photosensitive resin or a negative photosensitive resin, but a negative photosensitive resin is preferred because “film reduction” is small. Hereinafter, the case where the core portion 8 is formed of a negative photosensitive resin will be described. However, even if the core portion 8 is formed of a positive photosensitive resin, an optical waveguide having the optical path conversion mirror surface 9 of the present invention is manufactured. it can.

  As shown in FIGS. 3 (h) and 3 (h '), a negative photosensitive resin for forming a core portion is applied to the clad portion 3 having a groove having an inclined surface, and is heated and dried as necessary. A negative photosensitive resin layer 7 for forming is formed. As shown in FIGS. 3 (i) and (i ′), only the central part of the negative photosensitive resin layer 7 for forming the core part is irradiated with ultraviolet rays 5 through the pattern mask 4 to cure the uncured part. By dissolving and removing with a developer, the core portion 8 is formed as shown in FIGS. 3 (j) and (j ′). The core portion 8 has an inclined surface at the boundary with the clad portions at both ends, and this inclined surface becomes the optical path conversion mirror surface 9.

  FIGS. 3 (k) and (k ′) to FIGS. 4 (n) and (n ′) show the steps in which the optical path of the optical waveguide is secured and the cladding portion 3 is formed. In order to form the clad part 3 on the core part 8, as shown in FIGS. 3 (k) and (k ′), a positive photosensitive resin for clad part formation is applied on the core part 8 and necessary. Accordingly, the layer 2 of the positive photosensitive resin for forming the cladding portion is formed by heating and drying. In order to secure the optical path of the optical waveguide, as shown in FIGS. 4 (l) and (l ′), the positive photosensitive resin layer 2 for forming the cladding part on the upper part of the optical path conversion mirror surface 9 is passed through the pattern mask 4. 4 is irradiated with ultraviolet rays 5 to improve the solubility in the developer, and then dissolved and removed by the developer. As shown in FIGS. 4 (m) and (m ′), the optical path conversion mirror surface 9 A hollow portion serving as an optical path is formed at the top. The remaining layer 2 of the positive photosensitive resin for forming the cladding portion is cured by a conventional method as shown in FIGS. 4 (n) and (n ′), and the cladding portion 3 (upper cladding layer) is formed on the core portion 8. ) Is formed. As shown in FIGS. 4 (n) and (n ′), the optical path conversion mirror surface 9 can be used as an optical waveguide having an optical path conversion function even though it has a hollow portion. From the viewpoint of prevention and improvement of the reliability of the formed optical waveguide, it is preferable to form the core portion 8 also in this hollow portion.

  4 (o) and 4 (o ') to 4 (p) and 4 (p') show a process in which the core portion 8 is formed in the upper cavity portion of the optical path conversion mirror surface 9. As shown in FIGS. 4 (o) and (o ′), a negative photosensitive resin for forming a core part is applied to the hollow part of the optical path conversion mirror surface 9 and dried by heating as necessary. A layer 7 of a negative type photosensitive resin for partial formation is formed. As shown in FIGS. 4 (p) and (p ′), the core part-forming negative photosensitive resin layer 7 is cured by a conventional method to form the core part 8 in the hollow part. An optical waveguide having an optical path conversion function is completed.

  5 (A) and 5 (B) are schematic views showing the light path of the optical waveguide obtained by the manufacturing method of the present invention. As shown in FIG. 5A, incident light can be optically converted to about 180 ° by the two optical path conversion mirror surfaces 9 in the optical waveguide obtained by the manufacturing method of the present invention. In the case of changing the optical path of incident light to about 90 °, the optical waveguide having the two optical path conversion mirror surfaces 9 may be cut to form one optical path conversion mirror surface as shown in FIG.

  In the description using the drawings so far, the case where the optical waveguide is directly formed on the substrate has been described. However, the optical waveguide does not need to be formed directly on the substrate. For example, the optical waveguide manufacturing method of the present invention Thus, an optical waveguide may be formed on a film such as PET (polyethylene terephthalate) resin, and then the optical waveguide may be mounted on a substrate or the like.

As described above, in the production method of the present invention, the difference in the dissolution rate of the positive photosensitive resin layer 2 for forming the clad portion with respect to the developer between the non-photosensitive portion and the photosensitive portion is used. When there is a large difference in the dissolution rate between the non-photosensitive part and the photosensitive part in the developer, there is little “film reduction”. ) And the difference in dissolution rate is small, the “film reduction” increases, and the bottom surface of the non-exposed part and the side surface (inclined surface) of the non-exposed part due to “film reduction”. ) And the angle becomes smaller.
As described above, the angle of the optical path conversion mirror surface 9 obtained by the optical waveguide manufacturing method of the present invention is preferably an angle at which the optical path is converted to about 90 °, that is, about 45 ° with respect to the optical path. However, in order to obtain such an angle, it is necessary to set the dissolution rate of the non-photosensitive portion and the photosensitive portion in the developer to an appropriate range.

  In the production method of the present invention, the clad portion 3 is developed with an alkaline aqueous solution using a positive photosensitive resin capable of alkali development in order to form a good optical path conversion mirror surface 9 with little resist swelling during development. To do. Factors affecting the dissolution rate of the positive photosensitive resin in the developer include the type of base resin, the type and blending amount of the photosensitizer, the type and blending amount of the sensitizer, the type and developing temperature of the developer, and the like. . Since it is easy to adjust the dissolution rate of the non-photosensitive portion and the photosensitive portion in the developer, it is preferable to adjust such a dissolution rate depending on the amount of the photosensitive agent. When adjusting the dissolution rate depending on the blending amount of the photosensitizer, the greater the blending amount of the photosensitizer, the greater the difference in the dissolution rate of the non-photosensitive part and the photosensitive part with respect to the developer. In contrast, the inclination angle of the inclined surface is increased, and conversely, the smaller the blending amount of the photosensitive agent, the smaller the difference in dissolution rate, and the smaller the inclination angle of the inclined surface due to “film reduction” in the non-exposed portion.

  The photosensitizer used for adjusting the solubility is preferably a diazoquinone compound because of its high photosensitivity and easy adjustment of the dissolution rate, and the hydrogen atom of the compound having a phenolic hydroxyl group is represented by the following formula (1). A compound substituted with a group represented by the formula (4-diazonaphthoquinonesulfonic acid ester) or a compound substituted with a group represented by the following formula (2) (5-diazonaphthoquinonesulfonic acid ester) is more preferred.

  Preferable specific examples of such a diazoquinone compound include, for example, compounds represented by the following formulas (3) to (8) and their positional isomers.

（式（３）〜（８）中、Ｑは上記式（１）若しくは式（２）で表される基又は水素原子である。但し、それぞれの式において、全てが水素原子であることはない。）

(In formulas (3) to (8), Q is a group represented by the above formula (1) or formula (2) or a hydrogen atom. However, in each formula, not all are hydrogen atoms. .)

  Since the group represented by the formula (5) has absorption in the i-line (wavelength 365 nm) region, it is suitable for i-line exposure, and the group represented by the formula (6) has absorption in a wide wavelength range. Therefore, since it is suitable for exposure in a wide range of wavelengths, it is preferable to select either the group represented by the formula (5) or the group represented by the formula (6) depending on the wavelength to be exposed.

  According to the manufacturing method of the present invention, an optical waveguide having an optical path conversion function can be formed directly on a substrate. In such a substrate, since solder is used when mounting an optical element or the like, the material forming the optical waveguide is also required to have heat resistance. Examples of the positive photosensitive resin capable of forming an optical waveguide having high heat resistance include polysiloxane-based positive photosensitive resins. Among these, the positive photosensitive resin composition described in JP 2010-101957 A is used. Preferably, from the viewpoint of easy availability of raw materials and heat resistance of the obtained optical waveguide, as the component (A), a cyclic siloxane compound represented by the following general formula (9) and an arylalkoxy represented by the following general formula (10) A silicone resin obtained by reacting with a silane compound, a siloxane compound having a glycidyl group as the component (B), a diazonaphthoquinones as the component (C), particularly the hydrogen atom of the compound having a phenolic hydroxyl group described above A compound substituted with a group represented by the formula (1) (4-diazonaphthoquinonesulfonic acid ester) or the above formula (2) Compounds substituted with the group (5-diazonaphthoquinone sulfonic acid ester), and as component (D), the positive photosensitive composition containing an organic solvent is more preferable.

（式中、Ｒ¹は炭素数１〜３のアルキル基を表わし、ｍ、ｎ及びｐは、ｍ：ｎ：ｐ＝１：０〜２：０．５〜３であり、ｍ＋ｎ＋ｐ＝３〜６となる数を表す。）

(In the formula, R ¹ represents an alkyl group having 1 to 3 carbon atoms, m, n and p are m: n: p = 1: 0 to 2: 0.5 to 3, and m + n + p = 3 to 6) Represents the number of

（式中、Ｒ²及びＲ³は、それぞれ独立して炭素数１〜３のアルキル基を表わし、ｆは２〜３の数を表わす。）

(In the formula, R ² and R ³ each independently represents an alkyl group having 1 to 3 carbon atoms, and f represents a number of 2 to 3).

  A silicone resin obtained by reacting the cyclic siloxane compound represented by the general formula (9) and the arylalkoxysilane compound represented by the general formula (10), which is the component (A), has the following general formula (9a). ) And the arylalkoxysilane compound represented by the general formula (10) are reacted, and then the t-butyl ester group and the t-butyl ether group are described in JP-A No. 2010-101957. It can also be obtained by desorption by the above method.

（式中、ｍ、ｎ及びｐは、上記一般式（９）と同義である。）

(In the formula, m, n and p have the same meanings as in the general formula (9).)

（式中、ｘは３〜６の数を表わす。） As the siloxane compound having a glycidyl group, which is the component (B), a cyclic siloxane compound having a 3-glycidoxypropyl group represented by the following general formula (11) is used because of its excellent adhesion to the substrate. preferable.

(In the formula, x represents a number of 3 to 6.)

  As described above, the resin for forming the core part of the optical waveguide of the present invention is preferably a negative photosensitive resin because of less “film reduction” due to the developer. However, from the viewpoint of the heat resistance of the optical waveguide, Siloxane-based negative photosensitive resins are more preferable, and negative photosensitive resins described in JP-A No. 2004-010849 and negative photosensitive resins described in JP-A No. 2007-238868 are more preferable.

  The optical waveguide obtained by the production method of the present invention can be suitably used for an optical device such as an optical waveguide device, an optical integrated circuit, and an optical wiring board, particularly an optical device using a surface emitting laser as a light source.

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

[Manufacture of base resin A]
In accordance with the method for producing a cyclic siloxane compound (a-1) in Examples of JP 2010-101957 A, a cyclic siloxane compound of the following formula (12) was obtained.

  In a reaction vessel having a stirrer, a thermometer, and a refluxer, 100 parts by mass of the cyclic siloxane compound represented by the above formula (12) as the cyclic siloxane compound represented by the above general formula (9a), the above general formula (10) As an arylalkoxysilane compound represented by the formula, 40 parts by mass of phenyltrimethoxysilane and 200 parts by mass of toluene as a solvent are added, and 50 parts by mass of 5% oxalic acid aqueous solution is added over 30 minutes while stirring with ice cooling at 10 ° C. It was dripped. After stirring for 15 hours while maintaining the system temperature at 10 ° C., reflux dehydration / dealcoholation treatment was performed at 50 ° C. under reduced pressure. The solvent was exchanged to obtain a 25% PGMEA solution of the product. In order to remove the t-butyl group, 3 parts by mass of boron trifluoride diethyl ether complex was added, and after stirring at 80 ° C. for 3 hours, 100 parts by mass of the solvent was removed under reduced pressure. After adding 10 parts by mass of an adsorbent (manufactured by Kyowa Chemical Industry Co., Ltd., trade name: KYOWARD 500SH), the solid solution was removed from the slurry solution stirred at 80 ° C. for 1 hour by filtration, and a 30% PGMEA solution of base resin A Got. The base resin A is a compound corresponding to the silicone resin (a) in Examples of JP 2010-101957 A. The weight average molecular weight in terms of polystyrene as measured by GPC analysis using tetrahidolfuran as the base resin A was 6400, and the silanol group content measured by the method described in JP 2010-101957 A was 5.4% by mass. .

<Determination of blending amount of photosensitive agent for obtaining a 45 ° inclined surface>
As the component (A), a 30% PGMEA solution of the base resin A, and as the component (B), 2,4,6,8-tetrakis (3-glycidoxypropyl) -2,4,6,8- Tetramethylcyclotetrasiloxane, as the component (C), a compound in which all Qs in the above formula (3) are groups represented by the above formula (2) (manufactured by Daito Chemix, trade name: PA-6), and Using PGMEA as the component (D), each component was blended so as to have a ratio shown in [Table 1] to prepare compositions 1 to 8 which are positive photosensitive resin compositions.

(Method for preparing test piece)
A square glass substrate having a length of 25 mm and a width of 25 mm was used as a test piece forming substrate. On this test piece forming substrate, the compositions 1 to 8, which are the positive photosensitive resin composition, were applied by spin coating so that the thickness of the dried layer was 10 μm, respectively, and then the solvent was added. After volatilization and further heat treatment at 80 ° C. for 2 minutes to completely remove the solvent in the layer, irradiation with ultraviolet rays of 200 mJ / cm ² (wavelength 365 nm exposure conversion) with an ultra-high pressure mercury lamp, followed by 150 ° C. in an air atmosphere. It was cured by heat treatment for 60 minutes. On the cured surface, the same positive photosensitive composition as the cured surface was applied by spin coating so that the layer thickness after drying was 20 μm, and then the solvent was volatilized, followed by heat treatment at 80 ° C. for 2 minutes. The solvent in the layer was completely removed. A photomask having a slit width of 20 μm and a slit length of 10 mm was placed on the layer, and ultraviolet rays of 70 mJ / cm ² (wavelength 365 nm equivalent) were irradiated by an ultrahigh pressure mercury lamp. Next, this test piece was immersed in a 2.38 mass% tetramethylammonium hydroxide aqueous solution having a liquid temperature of 23 ° C. as a developer for 70 seconds, then washed with water and air-dried. The air-dried test piece was irradiated with ultraviolet rays of 200 mJ / cm ² (wavelength 365 nm exposure conversion) with an ultra-high pressure mercury lamp, and then heat-treated at 150 ° C. for 60 minutes in an air atmosphere. In order to measure the angle of the inclined surface of the cured product formed by “film reduction” with respect to the glass substrate, the test piece is cut in a direction perpendicular to the pattern, and the cut surface is enlarged using a scanning electron microscope. The angle between the glass substrate and the inclined surface was measured. The results are shown in [Table 1]. From the results of [Table 1], it was found that an inclination angle of 45 ° can be obtained by blending 7 parts by mass of the photosensitive agent (C) with respect to 100 parts by mass of the base resin A. Therefore, the composition 4 was used as a positive photosensitive resin composition for forming a core part.

<Manufacture of base resin B>
Base resin B was synthesized according to Example (A1) of JP-A-2007-238868. That is, 178.5 g (0.90 mol) of phenyltrimethoxysilane and 24.6 g (0.10 mol) of 3,4-epoxycyclohexylethyltrimethoxysilane were added to a reaction vessel having a stirrer, a thermometer and a refluxer. Then, 600 g of toluene was charged as a solvent, and 108 g of a 0.032 mass% phosphoric acid aqueous solution was added dropwise over 5 hours while cooling with ice, followed by further stirring for 5 hours. After adding 6.7 g of a 2% by mass aqueous sodium hydroxide solution, the mixture was heated to reflux toluene, and water was removed azeotropically. To seal the Si—OH group, 890 g (6.0 mol) of triethyl orthoformate was added, and the mixture was heated and stirred at 130 ° C. for 1 hour. 45 g of an adsorbent (trade name: KYOWARD 600S manufactured by Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was heated and stirred at 100 ° C. for 1 hour. After removing the adsorbent by filtration, volatile components were removed at 120 ° C. and 3 mmHg, 45 g of toluene and 1000 g of methanol were added to separate the two layers, and the lower layer was removed. Volatile components were removed at 110 ° C. and 3 mmHg to obtain a base resin B having an epoxy group. The polystyrene-reduced mass average molecular weight by GPC analysis using tetrahidolfuran of the base resin B as a solvent was 1800, and as a result of analysis by ¹ H-NMR, silanol groups (Si—OH) were not detected. Moreover, the epoxy equivalent measured by the potentiometric method was 1428.

<Preparation of negative photosensitive resin composition for core portion formation>
100 parts by weight of base resin B, 80 parts by weight of 2,2-bis (3,4-epoxycyclohexyl) propane, 20 parts by weight of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis- A composition comprising 0.6 parts by mass of [4- (bis (4-butoxyphenyl) sulfonio) phenyl] sulfide hexafluoroantimonate was used as a negative photosensitive resin composition for forming a core part.

[Formation of optical waveguide with optical path changer]
As shown in FIGS. 1 (a) and (a ′), after drying the composition 4 as a positive photosensitive resin composition for forming a clad portion on a square glass substrate 1 having a length of 25 mm and a width of 25 mm, after drying. After coating by spin coating so that the thickness of the layer becomes 30 μm, the solvent is volatilized and further dried by heating at 80 ° C. for 2 minutes to completely remove the solvent in the layer, and positive type photosensitivity for forming a clad part A layer 2 of the resin composition was formed.

The layer 2 of the positive photosensitive resin composition for forming a clad portion was irradiated with ultraviolet rays 5 of 200 mJ / cm ² (wavelength 365 nm exposure conversion) with an ultra-high pressure mercury lamp, and then heat-treated at 150 ° C. for 60 minutes in an air atmosphere. As shown in FIGS. 1B and 1B ′, the clad portion 3 (lower clad layer) was formed.

  As shown in FIGS. 1 (c) and (c ′), the above composition 4 as a positive photosensitive resin composition for forming a clad portion is formed on the clad portion 3 (lower clad layer). After coating by spin coating to a thickness of 30 μm, the solvent is volatilized, and further heated and dried at 80 ° C. for 2 minutes to completely remove the solvent in the layer, and a positive photosensitive resin composition for forming a clad part Layer 2 was formed.

As shown in FIGS. 1D and 1D ′, a photomask (pattern mask) 4 having a slit width of 30 μm and a slit length of 10 mm is placed on the layer 2 of the positive photosensitive resin composition for forming a clad part. By irradiating ultraviolet ray 5 of 70 mJ / cm ² (wavelength 365 nm exposure conversion) with an ultra-high pressure mercury lamp, the solubility of the exposed portion of the layer 2 of the positive photosensitive resin composition for forming a cladding portion in the developer is improved. It was.

  Thereafter, the exposed portion is immersed in a 2.38 mass% tetramethylammonium hydroxide aqueous solution having a liquid temperature of 23 ° C. as a developer for 70 seconds, as shown in FIGS. 2 (e) and (e ′). 2 (f) and (f ') are dissolved in the layer 2 of the positive photosensitive resin composition for forming a clad part by dissolving with a developing solution and dissolving the side surface of the non-exposed part exposed by dissolving the exposed part. A groove having an inclined surface due to film reduction as shown in FIG.

Next, the layer 2 of the positive photosensitive composition for forming a clad part in which a groove having an inclined surface is formed is irradiated with ultraviolet rays 5 of 200 mJ / cm ² (wavelength 365 nm exposure conversion) with an ultra-high pressure mercury lamp, and then the atmospheric atmosphere. By performing a heat treatment at 150 ° C. for 60 minutes at a lower temperature to cure, as shown in FIGS. 2 (g) and 2 (g ′), a clad portion 3 having a groove having an inclined surface was formed.

  After applying the negative photosensitive resin composition for core part formation obtained above to the groove having the inclined surface of the clad part 3 by spin coating so that the layer thickness after drying becomes 30 μm, the solvent Then, the solvent in the layer is completely removed by heating and drying at 80 ° C. for 2 minutes, and as shown in FIGS. 3 (h) and (h ′), the negative photosensitive resin composition for forming the core part is formed. Layer 7 was formed.

As shown in FIGS. 3 (i) and (i ′), a photomask (pattern mask) 4 having a slit width of 30 μm and a slit length of 250 μm is placed on the layer 7 of the negative photosensitive resin composition for core portion formation. Only the central part of the layer 7 of the negative photosensitive resin composition for forming the core part is irradiated with an ultraviolet ray 5 of mJ / cm ² (wavelength 365 nm exposure conversion) with an ultrahigh pressure mercury lamp and cured, and the uncured part is The core portion 8 was formed as shown in FIGS. 3 (j) and (j ′) by dissolving and removing with a mixed solution of 100 parts by mass of acetone and 100 parts by mass of isopropanol as a developer. The core portion 8 has an inclined surface at the boundary with the clad portions at both ends, and this boundary surface becomes the optical path conversion mirror surface 9.

  As shown in FIGS. 3 (k) and 3 (k ′), the composition 4 as a positive photosensitive resin for forming a clad portion is formed on the core portion 8 so that the layer thickness after drying becomes 60 μm. After coating by spin coating, the solvent was volatilized and further dried by heating at 80 ° C. for 2 minutes to completely remove the solvent in the layer, thereby forming layer 2 of a positive photosensitive resin composition for forming a cladding part.

As shown in FIGS. 4 (l) and (l ′), a photomask (pattern mask) 4 having a slit width of μm and a slit length of μm is placed on the layer 2 of the positive photosensitive resin composition for forming a cladding part. The positive photosensitive resin layer 2 for forming the cladding portion on the upper part of the optical path conversion mirror surface 9 is irradiated with ultraviolet rays 5 of 70 mJ / cm ² (wavelength 365 nm exposure conversion) with an ultrahigh pressure mercury lamp to improve the solubility in the developer. After that, the exposed portion was removed by immersing in a 2.38 mass% tetramethylammonium hydroxide aqueous solution having a liquid temperature of 23 ° C. as a developing solution for 70 seconds, as shown in FIGS. 4 (m) and (m ′). As shown, a hollow portion serving as an optical path was formed above the optical path conversion mirror surface 9. As shown in FIGS. 4 (n) and (n ′), the remaining layer 2 of the positive-type photosensitive resin for forming the cladding portion is irradiated with ultraviolet rays 5 of 200 mJ / cm ² (wavelength 365 nm equivalent) by an ultrahigh pressure mercury lamp. After that, the clad portion 3 (upper clad layer) was formed on the core portion 8 by curing by performing a heat treatment at 150 ° C. for 60 minutes in an air atmosphere.

As shown in FIGS. 4 (o) and (o ′), the core part-forming negative photosensitive resin composition obtained above is filled in the cavity part so that the cavity part is completely filled after drying. After coating by spin coating, the solvent is volatilized and further dried by heating at 80 ° C. for 2 minutes to completely remove the solvent in the layer, and as shown in FIGS. 3 (h) and (h ′), the core portion is formed. A layer 7 of the negative photosensitive resin composition for use was formed.
As shown in FIGS. 4 (p) and (p ′), the layer 7 of the negative photosensitive resin composition for forming the core part is irradiated with ultraviolet rays 5 of mJ / cm ² (wavelength 365 nm exposure conversion) with an ultrahigh pressure mercury lamp. Then, the core portion 8 was formed in the hollow portion and cured to complete an optical waveguide having an optical path conversion function.

  The obtained optical waveguide has a lower cladding layer thickness of 30 μm, an upper cladding layer thickness of 60 μm, a core portion thickness of 30 μm, a core portion width of 30 μm, a length between two optical path conversion surfaces of 10 mm, and between the waveguides. It had light conversion parts with an interval of 250 μm.

(Insertion loss measurement)
In order to evaluate the light insertion loss measurement of the optical waveguide obtained by the manufacturing method of the present invention, the light insertion loss was measured when light was inserted as shown in FIG. The insertion loss measurement conformed to the insertion loss measurement method of “Test method for polymer optical waveguide (JPCA-4PE02-05-1S-2008)” of the JPCA standard. In addition, an aligning machine manufactured by Suruga Seiki Co., Ltd. was used, and a 0.85 μm LED light source (manufactured by Anritsu, model: Stabilized Light Source MG-93B) was used as a measurement light source. Light is incident from one end face (incident end) of the test piece using a 50GI multimode fiber, light emitted from the other end face (exit end) of the test piece is received by the 200 PCF fiber, and light received by the fiber is detected. Measured with an instrument (manufactured by Anritsu, model MU931422A). In the measurement, a refractive index matching agent was used for each of the incident end and the exit end.
The average insertion loss of 10 optical waveguides obtained by the production method of the present invention was 3.5 dB, and it was confirmed that the optical waveguide had an excellent optical path conversion function.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Positive photosensitive resin layer 3 for forming a clad part 3 Cladding part 4 Pattern mask 5 Ultraviolet ray 6 Positive photosensitive resin layer 7 for forming a clad part whose solubility in a developer is improved by exposure 7 For forming a core part Negative photosensitive resin layer 8 Core portion 9 Optical path conversion mirror surface (inclined surface)
10 Path of light

Claims (3)

  In a method of manufacturing an optical waveguide in which a clad portion is formed of a positive photosensitive resin, an inclined surface formed by film reduction in the developing process of the positive photosensitive resin is used as an optical path conversion mirror surface. Manufacturing method of optical waveguide having conversion function (however, the above film reduction is a phenomenon in which the non-exposed portion is dissolved by the non-exposed portion being in contact with the developer for a long time in the development process of the positive photosensitive resin. ).   The method for producing an optical waveguide having an optical path conversion function according to claim 1, wherein a polysiloxane-based positive photosensitive resin is used as the positive photosensitive resin.   The method for manufacturing an optical waveguide having an optical path conversion function according to claim 1 or 2, wherein the core portion surrounded by the cladding portion is formed of a negative photosensitive resin.

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