JP3273519B2 - Method for manufacturing polysiloxane-based optical waveguide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polysiloxane-based optical waveguide which can be used as a waveguide for an optical integrated circuit.

[0002]

2. Description of the Related Art As a base material of an optical component or an optical fiber, inorganic materials such as quartz glass and multi-component glass, which are characterized by low optical transmission loss and a wide transmission band, are widely used. Recently, plastic-based materials have been developed, and since they are superior in workability and price as compared with inorganic materials, they are attracting attention as high-performance optical waveguide materials. For example, a flat optical waveguide having a core-cladding structure in which a plastic having excellent transparency such as polymethyl methacrylate (PMMA) or polystyrene is used as a core and a plastic having a lower refractive index than the core component is used as a cladding component is manufactured. [JP-A-3-188402]. However, these conventional plastic optical waveguides have a problem that the waveguide loss and heat resistance are lower than those of inorganic materials. In other words, with respect to the problem of waveguide loss, light is transmitted in the waveguide by totally reflecting the light incident on one end of the waveguide along the length direction. The degree to which light is attenuated by light absorption or scattering is greater in plastics than in inorganic materials. In particular, since the wavelength of light used for communication is between 650 nm and 1600 nm, it is necessary to reduce the loss of plastic in this wavelength region.
In addition, regarding the problem of heat resistance, since the glass transition temperature of plastic is generally around 100 ° C., the upper limit of the heat resistant temperature is about 70 ° C., and it is difficult to use a plastic waveguide as a practical one. there were. As a material for solving these problems, polysiloxane having low loss over the visible to near-infrared region and excellent heat resistance can be used (JP-A-3-43423). To produce a plastic optical waveguide using this material, a low-refractive-index polysiloxane serving as a clad and a high-refractive-index polysiloxane serving as a core are required. First, a low-refractive-index polysiloxane layer is formed on a substrate, and then a high-refractive-index polysiloxane layer serving as a core is formed thereon. Fine processing into a core shape. Specifically, a layer of a photosensitive resist is further formed on the polysiloxane layer, and using a resist pattern formed by exposure and development of the resist as a mask, wet etching using an organic solvent, or
Fine processing of the polysiloxane layer is performed by dry etching such as reactive ion etching. However,
The fine processing of polysiloxane involves difficulties as described below. That is, if the wet etching method is adopted, it is difficult to process the cross-sectional shape of the core into an appropriate square for isotropic etching with an organic solvent. Further, even if the anisotropic dry etching method is employed, there is a disadvantage that the etching rate is low and it takes a long time to perform fine processing of the core.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and its object is to
It is an object of the present invention to provide a method for efficiently and easily producing a plastic optical waveguide having low loss over the near infrared region and excellent heat resistance.

[0004]

SUMMARY OF THE INVENTION In general, the present invention relates to a method for manufacturing a polysiloxane optical waveguide, comprising the steps of: forming a lower cladding layer on a substrate;
In the method for producing a polysiloxane-based optical waveguide, which comprises a step of forming a core portion and a step of forming an upper clad, the step of forming the core portion comprises a step of insolubilizing a polymer by irradiation with far ultraviolet rays or an electron beam. It is characterized in that it is performed by a step of removing a portion. Is the the core member fees for use in the present invention method, the following general formula (Formula 1) or <br/> (of 2):

[0005]

Embedded image

[0006]

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Wherein R ₁ , R ₂ and R ₃ are the same or different and C _n Y _{2n + 1} (Y is hydrogen, deuterium or halogen, n
Is a positive integer of 5 or less), a deuterated alkyl group, a halogenated alkyl group, or C ₆
A phenyl group, a deuterated phenyl group, or a halogenated phenyl group represented by Y ₅ (Y is hydrogen, deuterium, or halogen), and R ₄ is C ₆ Y ₄ (Y is hydrogen, deuterium, or halogen) A phenylene group, a deuterated phenylene group,
Or a halogenated phenylene group, Z is hydrogen or deuterium, m is a positive number less than 100, and Y is all or a part of deuterium] or a polymer having a repeating unit represented by Chloromethylating part of the aromatic ring
Deuterated trichlorophenylsilane and deuterated dic
Copolymers obtained from lorodiphenylsilane
You.

The present inventors have conducted intensive studies and researches to solve the above-mentioned problems. As a result, unlike the conventional polysiloxane processed with the help of a resist, the present inventors insolubilized themselves by far ultraviolet rays or electron beams. The inventors have found that the above-mentioned problem can be solved by using a polysiloxane that enables direct processing.

That is, in the present invention, the processing of a polysiloxane into an optical waveguide, which has been conventionally performed, comprises forming a photosensitive resist layer, forming a resist mask by exposure and development, and then performing a conventional wet etching method using an organic solvent. In addition to the complicated processing procedure, the controllability of the waveguide shape and the processing efficiency are extremely low. The core portion is directly formed by using a polysiloxane which is insolubilized by the irradiation of the light. The inventors of the present invention have found that by adopting such a polysiloxane and a processing technique, the cross-sectional shape of the waveguide can be appropriately maintained and the processing efficiency can be improved.

An optical waveguide according to the present invention comprises: forming a lower clad on a substrate; forming a core portion; forming an upper clad;
It is manufactured through the following three steps. Hereinafter, the optical waveguide of the present invention and the method of manufacturing the same will be described in more detail step by step.

The substrate for forming the lower cladding is not particularly limited as long as it has a smooth surface. For example, a silicon wafer, quartz glass, multi-component glass, plastic plate, plastic film, ceramics, metal plate , Minerals, or a combination of these materials can be used.

The cladding polysiloxane to be formed thereon is not particularly limited as long as it has a lower refractive index than the polysiloxane to be used in the core portion described below. Oxane,
Polydiphenylsiloxane, a copolymer of trichlorophenylsilane and dichlorodiphenylsilane as monomers, and the like can be used. The clad layer on the substrate can be formed, for example, by spin-coating the solution containing the above-mentioned polysiloxane for cladding on the substrate and then drying, or by immersing the substrate in the solution and drying. That is, the method of forming the lower clad layer in the present invention is not limited. The lower cladding formed on the substrate may be a single composition or a mixture of a plurality of polysiloxanes. Further, a laminate of a plurality of polysiloxanes may be used.

A core layer is formed on the lower clad formed by the above method. As the polymer for forming an optical waveguide necessary for producing the polysiloxane-based optical waveguide of the present invention, those having a refractive index larger than that of the lower clad described above and being insolubilized by irradiation with far ultraviolet rays or electron beams. Used, such as those already described
In the general formula (Formula 1) or a polymer having a repeating unit represented by formula 2, or a part of an aromatic ring-chloro
Methylated, deuterated trichlorophenylsilane and heavy
Copolymers obtained from hydrogenated dichlorodiphenylsilane are exemplified . Specifically, for example, chloromethylated polyphenylsilsesquioxane, chloromethylated polydiphenylsiloxane, or the like in which a part of hydrogen of a phenyl group is deuterated can be used. If n is 6 or more, the glass transition temperature of the polymer decreases, and a problem occurs in heat resistance. Therefore, n is preferably 5 or less. The formation of the core layer
As in the case of the lower layer cladding, it can be performed by spin coating or immersion in a solution. The composition of the core layer is
A single polysiloxane or a mixture of a plurality of polysiloxanes may be used. A desired portion of the core layer thus formed is irradiated with far ultraviolet rays or an electron beam. In the case of irradiation with far ultraviolet rays, a mask is overlaid on the core layer or a mask pattern is formed by sputtering or the like, and far ultraviolet rays are irradiated from a mercury lamp or a commercially available exposure apparatus. In the case of electron beam irradiation, the electron beam is irradiated in a desired pattern directly on the core layer using an electron beam drawing apparatus. Through these steps, the polysiloxane is insolubilized in the portion irradiated with the far ultraviolet ray or the electron beam, and unnecessary polysiloxane other than this portion is dissolved and removed, thereby forming a core portion through which light is guided. For dissolving and removing unnecessary polysiloxane, a method of dipping the entire substrate in a solvent, a method of spraying a solvent on a core layer, or the like can be used.

The polysiloxane for the upper layer clad formed thereon is not particularly limited as long as it has a lower refractive index than the polysiloxane used for the above-mentioned core portion. desirable. The upper clad layer is, for example, spin-coated with a solution containing the above-mentioned polysiloxane on a substrate and then dried, or immersed in the solution and dried. For example, it can be formed in the same manner as when the lower clad is formed. That is, the method of forming the upper clad layer in the present invention is not limited. The upper clad formed may be a single composition, a mixture of a plurality of polysiloxanes, or a laminate of a plurality of polysiloxanes.

[0015]

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

Example 1 An optical waveguide was manufactured in which chloromethylated poly heavy phenylsilsesquioxane (chloromethylation ratio: 10%) was used as a core component, and polyheavy phenyl silsesquioxane was used as a lower layer and an upper layer cladding component. The above two polymers were used as methyl isobutyl ketone solutions. First, a clad component polymer was applied on a silicon substrate to a thickness of about 20 μm. heating·
After the drying treatment, the core component polymer was applied to a thickness of about 8 μm on the lower clad layer. After a photomask having a pattern of 8 μm is superposed thereon and subjected to insolubilization treatment by irradiation with far ultraviolet rays, methyl isobutyl ketone is sprayed to remove the core component of the non-insolubilized portion and lengthen the core polymer. Height 50mm, width 8μm, height 8
It was processed into a linear rectangular pattern of μm. A cladding component was applied thereon to obtain a waveguide. The waveguide loss was calculated to be 0.3 dB / cm or less when light having a wavelength of 1300 nm was incident from one end of the waveguide and the amount of light emitted from the other end was measured to calculate the loss of the waveguide. Also, -20 ° C to 15
No increase in waveguide loss was observed after performing the thermal cycle test at 0 ° C. 10 times.

Examples 2 to 4 In the same manner as in Example 1, optical waveguides were manufactured on a silicon wafer under various conditions. In each case, the core material was a material in which a part of the aromatic ring in the clad material was chloromethylated. The manufacturing conditions are summarized in Tables 1 and 2.

[0018]

[Table 1] Table 1 ──────────────────────────────────── Example No. Cladding material Chlormethylation rate ──────────────────────────────────── 1 Deuterated polyphenylsilsesquioxane 10 % 2 Deuterated polydiphenylsilsesquioxane 22% 3 Copolymer obtained from deuterated trichlorophenylsilane and deuterated dichlorodiphenylsilane 17% 4 Deuterated polymethylphenylsilsesquioxane 31% ── ──────────────────────────────────

[0019]

[Table 2] Table 2 Example No. Solvent Insolubilization method Core Developing method ──────────────────────────────────── 1 Methyl isobutyl ketone Irradiation with far ultraviolet rays Spraying solvent 2 Methyl isobutyl ketone Irradiate far ultraviolet rays Solvent spray 3 Methyl isobutyl ketone Irradiate far ultraviolet rays Solvent spray 4 Methyl ethyl ketone Electron beam irradiation Immerse in solvent ─────────────────────── ─────────────

When the waveguide loss and the heat resistance were evaluated using the manufactured optical waveguides in the same manner as in Example 1, it was confirmed that all the optical waveguides had extremely low waveguide loss and high heat resistance. Was.

[0021]

As described above, the polysiloxane-based optical waveguide according to the present invention has extremely excellent light transmission characteristics in the visible to near-infrared region as compared with conventional plastic optical waveguides, and also has a long time at high temperatures. Even if exposed, the decrease in performance is extremely small. Therefore, there is an advantage that it can be stably used as an optical integrated circuit component in the near-infrared region or an optical signal transmission medium for a distance of several hundred meters using a light source for the near-infrared region. In addition, since a direct waveguide processing procedure by insolubilizing only a desired portion is used in the manufacturing process, the manufacturing process can be simplified and
The controllability of the waveguide shape can be improved. That is, by these polymer materials and the manufacturing method of the optical waveguide,
There is an advantage that an optical signal transmission system such as a local area network which is excellent in economy can be configured.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C08G 77/24 C08G 77/385

Claims (1)

(57) [Claims] 1. A method for producing a polysiloxane-based optical waveguide, comprising: forming a lower clad layer on a substrate, forming a core portion, and forming an upper clad, wherein a core material used is: The following general formula (Formula 1)
Or a polymer having a repeating unit represented by (Chemical Formula 2),
Or a deuterated compound obtained by partially chloromethylating an aromatic ring.
Lichlorophenylsilane and deuterated dichlorodiphenyl
A polysiloxane-based copolymer, which is a copolymer obtained from silane, and wherein the core portion is formed by a step of insolubilizing a polymer by irradiation with far ultraviolet rays or an electron beam and a step of removing an unnecessary portion. Manufacturing method of optical waveguide. Embedded image Embedded image [Wherein R ₁ , R ₂ , and R ₃ are the same or different, and C _n Y
An alkyl group, a deuterated alkyl group, or a halogenated alkyl group represented by _{2n + 1} (Y is hydrogen, deuterium, or halogen, n is a positive integer of 5 or less), or C ₆ Y ₅ (Y
Is hydrogen, deuterium, or halogen), a phenyl group, a deuterated phenyl group, or a halogenated phenyl group,
R ₄ is a phenylene group, deuterated phenylene group, or halogenated phenylene group represented by C ₆ Y ₄ (Y is hydrogen, deuterium, or halogen); Z is hydrogen or deuterium; And Y is all or part of deuterium.]