JP3302157B2 - Method for manufacturing fluorinated polyimide 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 manufacturing a fluorinated polyimide optical waveguide, and more particularly to a method for manufacturing a simple fluorinated polyimide optical waveguide.

[0002]

2. Description of the Related Art With the practical use of optical communication systems by the development of low-loss optical fibers, development of various optical communication components has been desired. It is also desired to establish an optical wiring technology for mounting these optical components at a high density, particularly an optical waveguide technology. In general, optical waveguides are required to have conditions such as low optical loss, easy manufacture, control of the refractive index of the core and clad, and excellent heat resistance. As a low-loss optical waveguide, a silica-based optical waveguide is mainly studied. Quartz has a very good light transmittance as demonstrated in an optical fiber, so that even when used as a waveguide, 0.1 dB / cm at a wavelength of 1.3 μm.
The following low loss has been achieved. However, there are manufacturing problems such as a long time required for the production of the optical waveguide, a high temperature during the production, and difficulty in increasing the area.
On the other hand, polyimide having excellent heat resistance is widely used as an electronic material for an insulating film of an electronic component, a flexible printed wiring board, and the like, but there has been almost no record of application to an optical component such as an optical waveguide. From such a viewpoint, the present inventors are conducting research and development on polyimide optical materials. The present inventors have disclosed JP-A-4-873.
No. 4 discloses that by copolymerizing a fluorinated polyimide, it is possible to control the refractive index required for forming an optical waveguide. The optical waveguides using these fluorinated polyimides are disclosed in JP-A-4-98007, JP-A-4-235505 and JP-A-4-235506. The manufacturing method of these polyimide optical waveguides is a method using reactive ion etching (RIE) used in a semiconductor manufacturing process, has many manufacturing steps, and has a drawback that a long time is required for the manufacturing. There is a demand for a method of manufacturing an optical waveguide which can be manufactured in a short time with a small number of manufacturing steps, instead of the method of manufacturing these polyimide optical waveguides. In order to solve these problems, the present inventors have disclosed in Japanese Patent Application No. 5-271216 that it is possible to change the refractive index by irradiating a polyimide with radiation, and furthermore, to irradiate radiation. A polyimide optical waveguide with a polyimide core and a non-radiated polyimide clad was clarified. However, when preparing a polyimide optical waveguide by the method already reported, a simpler manufacturing method is further required because the manufacturing process includes a step of bonding the polyimide films to each other or spin coating the polyimide film separated from the substrate. It became.

[0003]

An object of the present invention is to provide a fluoride
An object of the present invention is to provide a simple manufacturing method of a light - polyimide optical waveguide.

[0004]

If outlined present invention, in order to solve the problems], according to the first invention is an invention relates to a method for producing a fluorinated polyimide optical waveguide, 350 ° C. or higher temperatures of this invention
Direct treatment of fluorinated polyimide produced by heat treatment
It is characterized in that a core having a refractive index changed in the depth direction of the optical waveguide is formed on the upper part of the lower clad by irradiating tangential radiation. The second invention of the present invention relates to another fluorine
The invention relates to a method for manufacturing a polyimide polyimide optical waveguide , comprising a heat treatment step at a temperature of 350 ° C. or more
The fluorinated polyimide is irradiated directly with radiation, and the refractive index changes in the depth direction of the optical waveguide in the upper part of the lower clad.
To produce a phased core, further off onto the fluorinated polyimide
A clad made of fluorinated polyimide is formed.

In view of the above situation, the present inventors have conducted intensive studies. As a result, when a polyimide film is irradiated with radiated light to produce a core, the irradiated light is irradiated under the condition that the back surface of the polyimide film is not transmitted. As a result, the present inventors have found that the object can be achieved, and have completed the present invention.

The polyimide used in the present invention can be produced, for example, from the following tetracarboxylic acid or a derivative thereof and a diamine. A polyimide alone, a polyimide copolymer, a polyimide mixture and, if necessary, additives such as an additive. There are those added.

[0007] Examples of the tetracarboxylic acid and its derivatives such as acid anhydrides, acid chlorides and esterified compounds are as follows. Here, an example of tetracarboxylic acid will be given. (Trifluoromethyl) pyromellitic acid, di (trifluoromethyl) pyromellitic acid, di (heptafluoropropyl) pyromellitic acid, pentafluoroethylpyromellitic acid, bis {3,5-di (trifluoromethyl) phenoxy} Pyromellitic acid, 2,3
3 ′, 4′-biphenyltetracarboxylic acid, 3,3 ′,
4,4′-tetracarboxydiphenyl ether, 2,
3,3 ′, 4′-tetracarboxydiphenyl ether, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 2,3,6,7-tetracarboxynaphthalene,
1,4,5,7-tetracarboxynaphthalene, 1,
4,5,6-tetracarboxynaphthalene, 3,3 ′,
4,4′-tetracarboxydiphenylmethane, 3,
3 ', 4,4'-tetracarboxydiphenyl sulfone, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, 5,5 '-Bis (trifluoromethyl) -3,3', 4,4'-tetracarboxybiphenyl, 2,2 ', 5,5'-tetrakis (trifluoromethyl) -3,3', 4,4'- Tetracarboxybiphenyl, 5,5'-bis (trifluoromethyl) -3,3 ', 4,4'-tetracarboxydiphenyl ether, 5,5'-bis (trifluoromethyl)-
3,3 ′, 4,4′-tetracarboxybenzophenone, bis {(trifluoromethyl) dicarboxyphenoxy} benzene, bis {(trifluoromethyl) dicarboxyphenoxy} (trifluoromethyl) benzene,
Bis (dicarboxyphenoxy) (trifluoromethyl) benzene, bis (dicarboxyphenoxy) bis (trifluoromethyl) benzene, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene, 3,4,9,10-tetra Carboxyperylene,
2,2-bis {4- (3,4-dicarboxyphenoxy) phenyl} propane, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, 2,2-bis {4-
(3,4-dicarboxyphenoxy) phenyl {hexafluoropropane, bis (trifluoromethyl) dicarboxyphenoxy} biphenyl, bis {(trifluoromethyl) dicarboxyphenoxy} bis (trifluoromethyl) biphenyl, bis} ( Trifluoromethyl)
Dicarboxyphenoxy diphenyl ether, bis (dicarboxyphenoxy) bis (trifluoromethyl) biphenyl, bis (3,4-dicarboxyphenyl) dimethylsilane, 1,3-bis (3,4-dicarboxyphenyl) tetramethyldi Siloxane, difluoropyromellitic acid, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene,
1,4-bis (3,4-dicarboxytrifluorophenoxy) octafluorobiphenyl and the like.

[0008] Examples of the diamine include the following. m-phenylenediamine, 2,4-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodulene, 4- (1H, 1H, 11H-eicosafluoroundecanooxy) -1,3-diaminobenzene, 4-
(1H, 1H-perfluoro-1-butanoxy) -1,
3-diaminobenzene, 4- (1H, 1H-perfluoro-1-heptanoxy) -1,3-diaminobenzene,
4- (1H, 1H-perfluoro-1-octanoxy)
-1,3-diaminobenzene, 4-pentafluorophenoxy-1,3-diaminobenzene, 4- (2,3
5,6-tetrafluorophenoxy) -1,3-diaminobenzene, 4- (4-fluorophenoxy) -1,3
-Diaminobenzene, 4- (1H, 1H, 2H, 2H-
Perfluoro-1-hexanoxy) -1,3-diaminobenzene, 4- (1H, 1H, 2H, 2H-perfluoro-1-dodecanoxy) -1,3-diaminobenzene,
p-phenylenediamine, 2,5-diaminotoluene,
2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-diaminobenzotrifluoride, bis (trifluoromethyl) phenylenediamine, diaminotetra (trifluoromethyl) benzene, diamino (pentafluoroethyl) benzene , 2,5-diamino (perfluorohexyl) benzene, 2,5-diamino (perfluorobutyl) benzene, benzidine, 2,2'-
Dimethylbenzidine, 3,3′-dimethylbenzidine,
3,3′-dimethoxybenzidine, 2,2′-dimethoxybenzidine, 3,3 ′, 5,5′-tetramethylbenzidine, 3,3′-diacetylbenzidine, 2,2′-
Bis (trifluoromethyl) -4,4′-diaminobiphenyl, octafluorobenzidine, 3,3′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 4,4′-diaminodiphenyl ether, 4,4 '
-Diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 2,2-bis (p-aminophenyl)
Propane, 3,3'-dimethyl-4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,2-bis (anilino) ethane, 2,2-bis (p- Aminophenyl) hexafluoropropane, 1,3-bis (anilino) hexafluoropropane, 1,4-bis (anilino) octafluorobutane, 1,5-bis (anilino) decafluoropentane, 1,7-bis (anilino ) Tetradecafluoroheptane, 2,2′-bis (trifluoromethyl) -4,
4'-diaminodiphenyl ether, 3,3'-bis (trifluoromethyl) -4,4'-diaminodiphenyl ether, 3,3 ', 5,5'-tetrakis (trifluoromethyl) -4,4'-diaminodiphenyl ether , 3,3'-bis (trifluoromethyl) -4,4 '
-Diaminobenzophenone, 4,4 ''-diamino-p
-Terphenyl, 1,4-bis (p-aminophenyl)
Benzene, p-bis (4-amino-2-trifluoromethylphenoxy) benzene, bis (aminophenoxy)
Bis (trifluoromethyl) benzene, bis (aminophenoxy) tetrakis (trifluoromethyl) benzene, 4,4 ′ ″-diamino-p-quarterphenyl, 4,4′-bis (p-aminophenoxy) biphenyl, , 2-bis {4- (p-aminophenoxy) phenyl} propane, 4,4'-bis (3-aminophenoxyphenyl) diphenylsulfone, 2,2-bis {4-
(4-aminophenoxy) phenyl} hexafluoropropane, 2,2-bis {4- (3-aminophenoxy)
Phenyl {hexafluoropropane, 2,2-bis} 4
-(2-aminophenoxy) phenyl} hexafluoropropane, 2,2-bis {4- (4-aminophenoxy) -3,5-dimethylphenyl} hexafluoropropane, 2,2-bis {4- (4- Aminophenoxy)-
3,5-ditrifluoromethylphenyl @ hexafluoropropane, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) biphenyl, 4,4'-bis (4-amino-3-trifluoromethylphenoxy) ) Biphenyl, 4,4′-bis (4-amino-2-trifluoromethylphenoxy) diphenylsulfone, 4,4 ′
-Bis (3-amino-5-trifluoromethylphenoxy) diphenylsulfone, 2,2-bis {4- (4-amino-3-trifluoromethylphenoxy) phenyl}
Hexafluoropropane, bis {(trifluoromethyl) aminophenoxy} biphenyl, bis [{(trifluoromethyl) aminophenoxy} phenyl] hexafluoropropane, diaminoanthraquinone, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, Bis {2-[(aminophenoxy) phenyl] hexafluoroisopropyl} benzene, bis (2,3,5,6-tetrafluoro-4-aminophenyl) ether, bis (2,3,5,6-tetrafluoro- 4-aminophenyl) sulfide, 1,3-bis (3-aminopropyl)
Tetramethyldisiloxane, 1,4-bis (3-aminopropyldimethylsilyl) benzene, bis (4-aminophenyl) diethylsilane, 1,3-diaminotetrafluorobenzene, 1,4-diaminotetrafluorobenzene, 4, 4'-bis (tetrafluoroaminophenoxy) octafluorobiphenyl and the like. Among these polyimides, for example, a fluorinated polyimide having fluorine, a fluorinated alkyl group, a fluorinated alkoxy group, or the like is preferable.

According to the present invention, a polyimide film formed on a substrate such as a silicon wafer by a method such as spin coating is irradiated with radiation light to form a polyimide optical waveguide having a core having an arbitrary size and shape. At this time, radiation light irradiation conditions such as radiation light energy and irradiation amount can be arbitrarily determined according to the type of polyimide film used, the thickness, the design value of the refractive index difference between the core and the clad, and the dimension of the core in the depth direction. It is an essential condition that radiated light does not penetrate to the back surface of the polyimide film. Thus, the first invention of the present invention can be realized, but the second invention can be realized by forming a polyimide film as an upper clad on the polyimide optical waveguide thus obtained.

A method for manufacturing a polyimide optical waveguide by irradiation of radiation according to the present invention will be described in comparison with a conventional method for manufacturing an optical waveguide using RIE. FIG. 1 is a view showing a process for producing a polyimide optical waveguide having a buried structure by irradiation with radiation light according to the present invention. FIG. 2 is a view showing a process of manufacturing a buried polyimide optical waveguide using a conventional RIE.

By selecting the energy of the emitted light, a core having an arbitrary depth and having a refractive index changed in the depth direction within the depth can be manufactured. In the case of manufacturing a buried waveguide, a method using RIE requires seven steps, whereas a method using radiation irradiation of the present invention can manufacture a polyimide optical waveguide in three steps. That is, a polyimide solution or a polyamic acid solution is applied on a substrate such as silicon by spin coating or the like, and then heated to remove a solvent and, if necessary, cure to obtain a polyimide film.
Next, the energy of the radiated light is selected so as to have a predetermined core depth, and the radiated light is irradiated so as to have a predetermined refractive index and a predetermined dimension to form a core. By further spin-coating the thus processed polyimide film, a polyimide optical waveguide having a buried structure can be formed without laminating the polyimide films or spin-coating the separated film. The mask shown here schematically shows a transmission type one-to-one X-ray mask in which the emitted light is masked so that the emitted light only strikes the core portion. However, an X-ray mask image of any magnification of reflection type or transmission type is formed on the polyimide film via the projection optical system,
The radiation may be applied only to the core portion.

It is also possible to perform various pretreatments of the material to be irradiated with the radiated light. For example, it may be left in an atmosphere filled with a certain substance and irradiated with radiation light to make the radiation light irradiation effect remarkable. Pre-processing according to a specific purpose can be freely set.

The shape of the waveguide can be freely set such as a straight line, a curve, a bend, an S-shape, a taper, a branch, an intersection, an optical directional coupler, a two-mode waveguide coupler, and a grating. Also, the width and depth of the core can be freely set.

[0014]

The present invention will be described in detail with reference to the following examples. It should be noted that the present invention is not limited to only these examples, and various types and various kinds of polyimide optical waveguides can be manufactured by changing the combination of materials, the shape of the waveguide, and the like. Is shown.

EXAMPLE 1 88.8 g of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride was placed in an Erlenmeyer flask.
(0.2 mol) and 64.0 g of 2,2-bis (trifluoromethyl) -4,4'-diaminobiphenyl (0.
2 mol) and N, N-dimethylacetamide 1000
g was added. The mixture was stirred under a nitrogen atmosphere at room temperature for 3 days to obtain a polyamic acid having a concentration of about 15% by weight.
This polyamic acid solution is spin-coated on a silicon wafer, and then heated in an oven at 70 ° C. for 2 hours, 160 ° C. for 1 hour, 250 ° C. for 30 minutes, and 350 ° C. for 1 hour to perform imidization to a thickness of 50 μm. Was obtained. This film was introduced into a vacuum device for radiation irradiation connected to a beam line. Further, a pattern having a width of 8 μm and a length of 30 mm was formed on the film by using emitted light having a peak energy of 100 eV. When the end face of the obtained polyimide optical waveguide was optically polished, light having a wavelength of 1.3 μm was made incident, and observed from a light emitting end face with a microscope equipped with an infrared camera, it was confirmed that the light was confined.

Example 2 88.8 g of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride was placed in an Erlenmeyer flask.
(0.2 mol) and 64.0 g of 2,2-bis (trifluoromethyl) -4,4'-diaminobiphenyl (0.
2 mol) and N, N-dimethylacetamide 1000
g was added. The mixture was stirred under a nitrogen atmosphere at room temperature for 3 days to obtain a polyamic acid having a concentration of about 15% by weight.
This polyamic acid solution is spin-coated on a silicon wafer and then heated in an oven at 70 ° C. for 2 hours, at 160 ° C. for 1 hour, at 250 ° C. for 30 minutes, at 380 ° C. for 1 hour, and imidized to a thickness of 50 μm. Was obtained. This film was introduced into a vacuum device for radiation irradiation connected to a beam line. Further, a pattern having a width of 8 μm and a length of 30 mm was formed on the film by using emitted light having a peak energy of 100 eV. Thereafter, a polyimide spin coat film was further spin-coated thereon to obtain a polyimide optical waveguide having a buried structure. When the end face of the obtained polyimide optical waveguide was optically polished, light having a wavelength of 1.3 μm was made incident, and observed from a light emitting end face with a microscope equipped with an infrared camera, it was confirmed that the light was confined. The polyimide optical waveguide having this buried structure was manufactured in three steps. Also, a polyimide optical waveguide having a buried structure could be produced without laminating the polyimide films and spin-coating the separated polyimide film.

Comparative Example 1 FIG. 2 shows a process of manufacturing a buried polyimide optical waveguide using a conventional RIE. A total of seven steps are required.

Comparative Example 2 FIG. 3 shows a process for producing a polyimide optical waveguide having a buried structure by the method proposed in Japanese Patent Application No. 5-271216. A total of five steps are required, and the method includes a step of bonding polyimide films to each other, and the yield is poor because voids are generated in the bonded portions.

[0019]

As described in the foregoing, by using the production method of fluorinated <br/> polyimide optical waveguide of the present invention, off
It is possible to reduce the number of manufacturing steps of a nitrided polyimide optical waveguide,
There is an effect that an optical waveguide having a buried structure can be easily formed without a spin coating operation on a fluorinated polyimide film or a peeled film.

[Brief description of the drawings]

Fluoride of buried structure by synchrotron radiation in the present invention; FIG
It is a figure which shows the manufacturing process of a pre- polyimide optical waveguide.

FIG. 2 is a diagram illustrating a process of manufacturing a buried polyimide optical waveguide using RIE according to the related art.

FIG. 3 is a view showing a conventional process of manufacturing a buried polyimide optical waveguide by irradiation with radiation light.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiaki Tamamura 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Tsuneyuki Haga 1-16-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Hiroo Kinoshita 1-6-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-4-274402 (JP, A) JP-A-5 -27132 (JP, A) JP-A-1-161718 (JP, A) JP-A-62-297807 (JP, A) JP-A-4-9807 (JP, A) JP-A-4-235506 (JP, A) JP-A-4-235505 (JP, A) JP-A-7-102088 (JP, A) Yoko Maruo et. al. , Proceedings of the Society of Polymer Science, Japan, May 12, 1993, Vol. 42 No. 3, p. 1140 Koichi Watanabe et. al. , 12th Japan Symposium Thermophysical Property ties, November 6, 1991, pp. 5-8 (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 6/12-6/14 C08J ⁷ /00-7/18

Claims (2)

(57) [Claims] 1. A heat treatment step at a temperature of 350 ° C. or higher.
Irradiate the fluorinated polyimide, which was manufactured to contain it, with the upper part of the lower clad and bent in the depth direction of the optical waveguide.
Fluorine characterized by producing a core with a changed folding ratio
Of manufacturing a modified polyimide optical waveguide. 2. A heat treatment step at a temperature of 350 ° C. or more.
Directly irradiate the fluorinated polyimide, which was made containing, with the upper part of the lower clad in the depth direction of the optical waveguide.
To prepare a core refractive index is changed, further method for producing a fluorinated polyimide optical waveguide, and forming a cladding made of fluorinated polyimide on the fluorinated Porii <br/> on bromide.