JPH08278402A - Preparation of optical resin film - Google Patents

Abstract

PURPOSE: To provide a preparing method of an optical resin film applicable for evening a substrate used for a waveguide type optical element, etc. CONSTITUTION: This preparing method includes a process to dispose a thermoplastic resin 64 which is not decomposed but has presents fluidity at temp. higher than heat distortion temp. on a flat part 62 and a recessed part of the substrate 61 having the recessed part which is nearly surrounded by this flat part 62, a process to dispose a flat plate 65 on the thermoplastic resin 64 so as to reach the flat part 62 of the substrate 61 to heat the resin 64 and the process to remove flat plate 65. A smoothness of the flat plate 65 is less than 1/10 of the wave length to be used.

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 an optical resin film applicable to the flattening of a substrate for an optical waveguide element used in the fields of optical communication and optical information processing. The method for producing an optical resin film of the present invention can be applied to a single lens such as a lens or an optical component exhibiting a function.

[0002]

2. Description of the Related Art Conventionally, a waveguide type optical element uses Si, glass, ceramics, an inorganic crystal or a polymer material as a substrate, and a clad constituting a waveguide on the substrate, and a glass, an inorganic crystal or a polymer material as a core material. LS
A high-performance waveguide type optical element was manufactured by performing microfabrication by a combination of photolithography and dry etching processes often used in the I process (for example,
Optical and Quant by Masao Kawauchi
um Electronics 22: 391 (1990)).

However, in general, when the substrate for mounting or manufacturing optical elements or the like has an uneven shape, a fine pattern is formed when performing fine processing, unlike resist pattern formation on a plane. Difficult to form, μm
There is a drawback that inconvenience occurs in terms of forming a waveguide on the order or aligning an optical element that requires accuracy on the order of μm.

There is also a drawback that the resist work itself is difficult when the height of the unevenness of the substrate is 100 μm or more.

In the production of a polymer waveguide, it is common to apply a core material and a clad material by a spin coating method, which is said to have the most uniform film thickness, and then form a pattern with a resist ( For example, Mr. Imamura and others, Select
ronics Letters 27: 1342 (1991)).

Here, an example of producing a polymer waveguide will be described with reference to FIG. As shown in FIG. 1, the substrate 1 has a convex portion 1a and a flat portion 1b on its surface. Even if a coating film such as a clad material is formed on the substrate 1 by the spin coating method, the film thickness t ₁ in the vicinity of the convex portion 1a and the flat portion 1 are
There is an extreme difference from the film thickness t ₂ at b. For this reason,
The uniformity of the film thickness of the resist itself, which is often used in the pattern formation of the waveguide circuit, cannot be obtained either, which makes it difficult to form the core pattern thereafter, or, as shown in FIG. There is a drawback in that the height of the core portion 3 patterned on the surface 2 is not uniform and high-performance waveguide characteristics cannot be obtained. In FIG. 2, reference numeral 4 is an upper clad portion.

This situation uses other waveguide materials,
This is also the case when patterning is performed using a resist, and there is the inconvenience that a high-performance waveguide element cannot be obtained due to the influence of the uneven shape of the substrate.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing an optical resin film applicable to flatten a substrate used for a waveguide type optical element.

[0009]

In order to achieve the above-mentioned object, the invention according to claim 1 is a method for producing an optical resin film, in which a photocurable or thermosetting resin raw material is mainly used on a substrate. A step of forming a film of an optical material as a component, and after arranging a flat plate on the surface of the optical material film, the optical material is polymerized by light irradiation or heating with the substrate above or below to form a cured film. The method is characterized by including a step of forming and a step of removing the flat plate.

Here, the invention according to claim 2 is the invention according to claim 1.
In the method for producing an optical resin film described above, the optical material may contain a monomer or oligomer having an epoxy ring as a main component and further contain a polymerization initiator.

According to a third aspect of the present invention, in the method for producing an optical resin film according to the first aspect, the optical material contains a monomer or oligomer having an unsaturated group as a main component and further contains a polymerization initiator. It may be.

According to a fourth aspect of the present invention, in the method for producing an optical resin film according to the first aspect, the optical material contains a monomer or oligomer having a siloxane bond as a main component and further contains a polymerization initiator. May be.

The invention according to claim 5 is defined by claims 1 to 4.
In the method for producing an optical resin film according to any one of the items, the flat plate or the substrate is a transparent plate having optical transparency, the optical material is photocurable, and the light irradiation is It may be performed through a transparent plate.

According to a sixth aspect of the present invention, in a method for producing an optical resin film, a step of disposing a resin exhibiting fluidity without being decomposed at a heat deformation temperature or higher on a substrate, and a flat surface on the resin. And a step of heating the resin by disposing a flat plate, and a step of removing the flat plate.

According to a seventh aspect of the present invention, in the method for producing an optical resin film, a substrate having a flat portion and a concave portion substantially surrounded by the flat portion is not decomposed above the thermal deformation temperature on the concave portion. A step of disposing a resin exhibiting fluidity on the resin, a step of disposing a flat plate on the resin so as to reach the flat part of the substrate and heating the resin, and a step of removing the flat plate. It is characterized by including.

Here, in the step of arranging the flat plate on the resin, it is necessary that the surplus resin does not push up the flat plate, and the surplus resin is caused to overflow. this is,
This is to increase the smoothness of the surface of the resin film finally obtained. In addition, it is necessary to use an amount of resin that exceeds the inner volume of the recess of the substrate. This is to form a resin film having a smooth surface in which recesses are embedded on the substrate.

The invention described in claim 8 is the invention as claimed in claims 1 to 7.
In the method for producing an optical resin film described in any one of 1 above, the flatness of the flat plate is 1/10 of a wavelength used.
It may be the following.

Here, a method for producing the optical resin film of the present invention will be schematically described with reference to FIGS. 3 (a) and 3 (b). 3A and 3B are cross-sectional views showing an example of an embodiment of the method for producing an optical resin film of the present invention.

First, as shown in FIG. 3A, the convex portion 31
A substrate 31 having a and a flat portion 31b is prepared, and a coating film 32 made of a monomer curable by heat or light is formed on the substrate 31. This coating method may be spin coating, dipping, or simply applying onto a part of the substrate.

Next, a die 33 having a flat surface is placed on the coating film 32, and even pressure is applied to the die 33 toward the coating film 32, and then heat or light is irradiated to apply the coating. Membrane 3
2 is polymerized to form a polymer film 34.

By such an operation, the polymer film 34 is flattened irrespective of the degree of irregularities of the substrate 31 depending on the surface accuracy of the die 33. As the monomer material of the coating film 32 used at this time, a material having an appropriate viscosity at room temperature is an epoxy ring,
The skeleton thereof may be any of acrylate-based, silicone-based, imide-based, amide-based, and the like, as long as it has an unsaturated group and the like and is polymerized.

Further, the thickness of the polymer film 34 can be controlled to an arbitrary thickness by the pressure applied from the mold 33, the viscosity of the coating film 32 before polymerization, and the like.

Further, instead of the monomer material of the coating film 32, a polymer material which does not decompose when heated to a temperature higher than the heat distortion temperature and exhibits fluidity can be used. In this case,
With pressure applied by the mold 33, the coating film 32 made of a polymer material is heated to a temperature not lower than the heat deformation temperature to make the polymer material fluid and flat, and then cooled to room temperature. However, the same operation can be performed. As the polymer material in this case, almost all thermoplastic resins such as ester, acryl, imide, amide, silicone and epoxy can be used as long as they are hard to be decomposed at a glass transition point or higher.

Further, since the smoothness of the flat die directly affects the optical characteristics of the waveguide element according to the method of the present invention,
is important. When the smoothness is λ / 10 or more, the unevenness affects the optical loss of the waveguide element, especially the scattering loss,
It becomes a loss source of about several dB. Further, since it is not possible to secure the alignment accuracy of several μm or less, which is necessary for the alignment of the optical element, the smoothness of the mold is preferably λ / 10 or less.

[0025]

EXAMPLES Examples of the present invention will be described in detail below with reference to specific examples.

Example 1 (a) to (c) of FIG. 4 are sectional views for explaining each step in one example of the optical resin film of the present invention. As shown in FIG. 4A, a 3-inch Si substrate 4 in which convex portions 41 of 50 μm in height and 2 mm square are arranged at intervals of 5 mm.
I prepared 2.

Next, as shown in FIG. 4B, 0.4 cc of a photocurable epoxy material (viscosity 100 cp) containing a material having the following structure as a main component is applied on the substrate 42 to form a coating film. 43 is provided. Next, as shown in FIG. 4C, a transparent glass mold 44 (surface accuracy, λ / 10) is placed on the coating film 43 while expelling bubbles, and then UV is applied.
Irradiation with light (wavelength 350 nm) cures the coating film 43 to form a cured film 45. When the surface accuracy of the upper surface of the cured film 45 was measured by the interferometry, the surface accuracy was equivalent to that of the mold 44.

[0028]

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Example 2 Using the same substrate as in Example 1, 0.4 cc of thermosetting epoxy resin (viscosity 100 cp) containing the above structure as a main component was applied as the material of the coating film 43 and the same operation was performed. After covering with the mold 44, it was heated to 100 ° C. to obtain a cured film 45. When the surface accuracy of the upper surface of the cured film 45 was measured by the interferometry, the surface accuracy was almost the same as that of the mold 44 as in Example 1.

Example 3 Using the same substrate as in Examples 1 and 2, the coating film 43 was used.
As a material, a photocurable acrylic resin (viscosity 100 cp) containing the following structure as a main component was placed at 0.4 cc, and the same operation was performed. It was

[0031]

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[0032]

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Example 4 Using the same substrate as in Examples 1 to 3 and applying 0.4 cc of a photocurable silicone resin (viscosity 100 cp) containing the following structure as a main component as the material of the coating film 43, the same operation As a result, the surface accuracy was almost the same as that of the mold 44 as in the first embodiment.

[0034]

[Chemical 4]

[0035]

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Example 5 Using the same substrate as in Examples 1 to 4, beads or fine powder (Tg 140 °) of thermoplastic resin containing the following structure as a main component was used as the material of the coating film 43 on the substrate 42. On the mold 44 while heating to 250 ° C. (surface accuracy, λ / 1
0) was added while expelling bubbles. Next, when the mold 44 was removed by cooling to room temperature, the substrate 42 was flattened and its surface accuracy was almost the same as that of the mold 44 as in the first embodiment.

[0037]

[Chemical 6]

Next, an example of producing a waveguide element to which the method for producing an optical resin film of the present invention is applied will be described.

Manufacturing Example 1 FIGS. 5A to 5F are cross-sectional views showing, in the order of steps, a manufacturing example of a waveguide element to which the method for manufacturing an optical resin film of the present invention is applied.

As shown in FIG. 5A, the same thermoplastic resin 64 as in Example 5 was placed on the concave portion of the substrate 61 having the flat portion 62 and the hole 63. Here, the substrate 61 has a low smoothness except for the flat portion 62 and has a rough surface. Next, as shown in FIG. 5B, a plate 65 having a flat bottom was placed on the thermoplastic resin 64. What should be noted here is FIG.
After the heating step shown in (c), when the resin is deformed, it is necessary to place the plate 65 on the flat portion 62 of the substrate 61 as shown in FIG. 5D. . When the resin 64 is polymerized and deformed by heating, the polymerized resin 66 is pushed by the plate 65, the upper surface thereof is flattened, and the resin surplus 67 protrudes from the concave portion of the substrate 61 through the hole 63 and solidifies after the heating is completed. To do. Next, the plate 65 is removed as shown in FIG. 5 (e), and the resin surplus 67 is removed as shown in FIG. 5 (f). As a result, the upper surface of the substrate 61 was flattened, and its surface accuracy was almost the same as that of the mold 44, as in the first embodiment.

It should be noted that by providing a groove in the flat portion 62 instead of the hole 63 in the first manufacturing example, the excess resin can be discharged to the outside of the concave portion of the substrate 61. In addition, in all of the examples including this manufacturing example, the same effect can be obtained even if the operation is performed upside down as shown in FIG. 6 instead of FIG. 5C.

Fabrication Example 2 FIGS. 7A to 7F are cross-sectional views showing a fabrication example of a waveguide element to which the method for fabricating an optical resin film of the present invention is applied in the order of steps.

The substrate 51 shown in FIG. 7A is a 3-inch S having a convex portion 52 for mounting an optical element such as a light emitting / receiving element.
i substrate. The size of the table is 2 x 2 mm and the height is 100μ.
m. Next, as shown in FIG. 7B, 0.5 cc of epoxy UV resin monomer (viscosity 200 cps, refractive index 1.51) was dropped on the substrate 51 to form a coating film 53. Next, as shown in FIG. 7C, a glass substrate (3 inches) 54 having a mirror surface finish with a smoothness of λ / 10 or less is covered on the coating film 53, and UV light is removed while removing bubbles. (Wavelength 350 nm) 55 was irradiated. After that, FIG.
As shown in (d), when the glass substrate 54 was peeled off, the cured film 56 had a film thickness of 110 μm, its upper surface was flattened (smoothness of about λ / 10), and the convex portions 52 were formed in the cured film 56. Was embedded in. After that, as shown in FIG. 7 (e), reactive ion etching (R
The polymer film 56 was etched using IE) until the upper surface of the protrusion 52 was exposed. As a result, the 3-inch Si substrate apparently became a flat substrate, and patterning using photolithography became possible as in the usual method. Next, as shown in FIG. 7F, photolithography and RIE are performed using a polymer waveguide material 57 (refractive index 1.52) having a higher refractive index than the coating film 53 with respect to the upper surface of the substrate 51. The waveguide core portion 57 was formed by a technique so as to be in contact with the convex portion 52. After that, when the LD element 58 was bonded onto the convex portion 52 and an optical coupling between the LD element 58 and the waveguide core portion 57 was tried, the coupling loss was about 3 dB.

Manufacturing Example 3 A waveguide core portion 57 was manufactured by the same method as in Manufacturing Example 2, and a PD was placed on the convex portion 52 shown in FIG. 7 and optically coupled, and the coupling loss was about 2 dB. .

Manufacturing Example 4 When another waveguide was placed on the convex portion 52 shown in FIG. 7 in the above Manufacturing Example 2 and optical coupling was attempted, the coupling loss was 0.2d.
It was about B.

Although the convex portion 52 in the above-described manufacturing example has a convex shape, it is needless to say that the same effect can be obtained even if the concave portion and the V-shaped groove are formed, and the same effect can be exhibited in coupling with an optical fiber.

[0047]

As described above, according to the present invention,
An optical resin film excellent in surface accuracy can be easily produced. Therefore, by forming an optical waveguide on the optical resin film produced in this way, or by mounting an optical component such as a lens that also exerts a function, a waveguide type that exhibits high-performance waveguide characteristics. It becomes possible to manufacture an optical element. Further, the optical coupling on the produced optical resin film has a small coupling loss, which is useful in the fields of optical communication and optical information processing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a conventional general film thickness distribution.

FIG. 2 is a cross-sectional view showing a conventional core portion film thickness distribution.

3 (a) and 3 (b) are cross-sectional views showing an example of an embodiment of a method for producing an optical resin film of the present invention.

FIGS. 4A to 4C are cross-sectional views for explaining each step in the first embodiment of the optical resin film of the present invention.

5A to 5F are cross-sectional views showing, in the order of steps, an example of manufacturing a waveguide element to which the method for manufacturing an optical resin film of the present invention is applied.

FIG. 6 is a cross-sectional view showing a modified example of the manufacturing example of the waveguide element shown in FIG.

7A to 7F are cross-sectional views showing, in the order of steps, another example of manufacturing a waveguide element to which the method for manufacturing an optical resin film of the present invention is applied.

[Explanation of symbols]

 1 Concavo-convex substrate 1a Convex part 1b Flat part 2 Lower clad part 3 Core part 4 Upper clad part 31 Substrate 31a Convex part 31b Flat part 32 Coating film 33 Mold 34 Polymer film 41 Convex part 42 Si substrate 43 Coating film 44 Transparent glass Mold (surface accuracy, λ / 10) 45 Cured film 51 Substrate 52 Convex portion 53 Coating film 54 Glass substrate 55 UV light (wavelength 350 nm) 56 Cured film 57 Waveguide core portion 58 LD element 61 Substrate 62 Flat portion 63 Hole 64 Thermoplastic resin 65 Plate 66 Cured resin film 67 Resin surplus

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Claims (8)

[Claims] 1. A method for producing an optical resin film, comprising a step of forming a film of an optical material containing a photocurable or thermosetting resin raw material as a main component on a substrate, and forming a film on the surface of the optical material film. After disposing a flat plate, the step of polymerizing the optical material by light irradiation or heating with the substrate above or below to form a cured film, and a step of removing the flat plate, A method for producing an optical resin film. 2. The method for producing an optical resin film according to claim 1, wherein the optical material contains a monomer or oligomer having an epoxy ring as a main component, and further contains a polymerization initiator. 3. The method for producing an optical resin film according to claim 1, wherein the optical material contains a monomer or oligomer having an unsaturated group as a main component, and further contains a polymerization initiator. 4. The method for producing an optical resin film according to claim 1, wherein the optical material contains a monomer or oligomer having a siloxane bond as a main component, and further contains a polymerization initiator. 5. The flat plate or the substrate is a light-transmissive transparent plate, the optical material is photocurable, and the light irradiation is performed through the transparent plate. 5. The method for producing an optical resin film according to any one of 1 to 4. 6. A method for producing an optical resin film, comprising a step of disposing a resin exhibiting fluidity without decomposing above a heat distortion temperature on a substrate, and disposing a flat plate on the resin. A method for producing an optical resin film, comprising: a step of heating the resin; and a step of removing the flat plate. 7. A method for producing an optical resin film, wherein a resin exhibiting fluidity without being decomposed at a thermal deformation temperature or higher is present on the concave portion of a substrate having a flat portion and a concave portion substantially surrounded by the flat portion. And a step of disposing a flat plate on the resin so as to reach a flat portion of the substrate to heat the resin, and a step of removing the flat plate. A method for producing an optical resin film. 8. The flatness of the flat plate is not more than 1/10 of the wavelength used, and the flatness is 1-10.
The method for producing an optical resin film according to any one of 1.