JPH09222524A - Production of polyimide optical waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and cost effectively obtain an optical waveguide by cutting a second polyimide layer down to a first polyimide layer leaving a specified width and providing the side parts and upper part of a core with the same polyimide layer as the first layer. SOLUTION: Polyimide is applied on a substrate 1 and is heated to form a lower clad layer 2a. The polyimide having the refractive index higher than the refractive index of the material formed as the clad layer 23a is used and is similarly layered to form a core layer 3. The laminate of the lower clad layer 2a and the core layer 3 is cut on its both sides leaving the width to be formed the core down to the lower clad layer 2a by using a dicing machine. Further, the substrate is subjected to grooving by using the dicing machine. Namely, both sides of the substrate 1 leaving the width to be formed as the core are subjected dicing down to the lower clad layer 2a from the core layer 3. The front surface and flakes of the core part 3a formed by the cutting are provided with the material of the same compsn. as the compsn. of the lower clad layer as the upper clad layer 2b.

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 polyimide optical waveguide, and more particularly to a simple and economical manufacturing method suitable for a polyimide optical waveguide having a linear core pattern.

[0002]

2. Description of the Related Art Various optical communication components have been developed with the practical use of optical communication systems by developing optical fibers. As the optical wiring (optical waveguide) for mounting these optical communication components, low loss silica-based materials that have been proven in optical fibers have been mainly studied, but silica-based materials require a long time for optical waveguide fabrication. However, there are drawbacks in manufacturing, such as high temperature, 1000 ° C. or higher at the time of manufacturing, difficulty in increasing the area, and lack of flexibility, which makes it difficult to handle. Therefore, in recent years, studies on optical waveguides of organic polymer materials have been widely conducted in order to solve these problems.

[0003] Among organic polymer materials, polyacrylates such as polymethyl methacrylate having light transmissivity can be molded at a low temperature and have flexibility as compared with quartz-based materials. Poor heat resistance. JP-A-4-
No. 9807 proposes a polyimide-based optical waveguide which has excellent heat resistance, electrical properties, and mechanical properties and has a proven track record in electronic materials such as insulating films and printed wiring boards. Polyimides, especially fluorinated polyimides, have excellent light transmission, heat resistance and moisture resistance, and the required refractive index difference between the cladding part and the core part of the optical waveguide can be controlled by changing the composition of the polymerization component. It has the property that it can be easily performed. Further, the heat resistance temperature is 300 ° C. or higher, and the electronic material has heat resistance at the time of solder bonding. In the above publication, a polyimide core layer having a larger refractive index is formed on the lower cladding layer of polyimide, and an aluminum layer is formed thereon by vapor deposition, resist coating, pre-baking,
Exposure, development and after-baking are performed to form a patterned resist layer, aluminum is removed by wet etching, polyimide is removed by dry etching, and finally the remaining aluminum layer is removed by wet etching. Optical waveguides are manufactured by methods including active ion etching (RIE).

As another method for producing a polyimide-based optical waveguide, a fluorinated polyimide is irradiated with an electron beam (radiation light) through a mask to increase the refractive index of an irradiated portion above the lower clad to form a core of the optical waveguide. A method is disclosed in which a polyimide layer having the same composition as that of the lower clad is provided thereon as necessary to form an upper clad (Japanese Patent Application Laid-Open Nos. 7-12088 and 7-209537). According to this method, the RI
Compared with the E method, the manufacturing process can be greatly simplified, free drawing is possible, and the core width can be freely changed.

[0005]

However, in the above method, the electron beam is applied to the pattern of the core, so that a highly accurate and expensive electron beam drawing apparatus is required. Therefore, an object of the present invention is to provide a method capable of efficiently producing a polyimide-based waveguide in a short process without using the RIE method and without using an electron beam drawing apparatus.

[0006]

When the core pattern of the optical waveguide is relatively simple such as linear, the present inventors use a dicing machine which is generally used for forming a silicon wafer into chips. As a result, it was confirmed that an optical waveguide can be efficiently manufactured, and the present invention was completed.

That is, according to the present invention, a first polyimide layer and a second polyimide layer having a refractive index higher than that of the first polyimide layer are laminated in this order on a substrate, and a second dicing machine is used. The polyimide layer is cut to reach the first polyimide layer leaving a width to be the core, and then the same polyimide layer as the first layer is provided on the side and the upper part of the core portion. A method for manufacturing a system optical waveguide is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, polyimide is used as a clad and a core. Such a polyimide can be produced from tetracarboxylic acid or its derivative and diamine. As the polyimide, a simple substance of polyimide, a polyimide copolymer, a mixture of two or more kinds of polyimides, and a material to which other additives are added are used. Particularly preferred is a fluorinated polyimide obtained from one or both of an acid dianhydride and a diamine having a fluorine atom bonded thereto.

Specific examples of the tetracarboxylic acid and its derivative and the diamines, which are the raw materials of such polyimide and fluorinated polyimide, include the following. (Trifluoromethyl) pyromellitic acid, di (trifluoromethyl) pyromellitic acid, di (heptafluoropropyl) pyromellitic acid, pentafluoroethylpyromellitic acid, bis {3,5-di (trifluoromethyl)
Phenoxydipyromellitic 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'-tetracarboxydiphenylsulfone, 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, 3,4,9,1
0-tetracarboxyperylene, 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) tetramethyldisiloxane, difluoropyromellitic acid,
4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene, 1,4-bis) 3,4-
Dicarboxytrifluorophenoxy) octafluorobiphenyl and the like.

[0010] 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- (1Η, 1H-perfluoro-1-heptanoxy) -1,3-diaminobenzene,
4- (1Η, 1Η-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, 1Η, 2Η, 2Η-
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 (amino) Phenoxy) tetrakis (trifluoromethyl) benzene,
4,4 "'-diamino-p-quarterphenyl,
4,4'-bis (p-aminophenoxy) biphenyl,
2,2-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-trifluoromethyl) Phenoxy) biphenyl, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) diphenyl sulfone, 4,4 '
-Bis (3-amino-5-trifluoromethylphenoxy) diphenyl sulfone, 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 etc.

The manufacturing method of the present invention will be described with reference to the accompanying drawings. 1A to 1C are sectional views showing an optical waveguide forming step according to the present invention, wherein FIG. 1A is a step of forming a lower clad layer and a core layer, FIG. 1B is a cutting step, and FIG. A clad layer formation process is shown. Hereinafter, each step will be described.

Step (a) A lower clad layer (2a) and a core layer (3) are sequentially formed on the substrate (1). As the substrate (1), a mirror-polished one having high smoothness such as quartz or silicon is used.
In this step, a polyimide for a clad layer is applied onto the substrate 1 by a spin coating method and heated to form a lower clad layer (2a). The thickness of the lower clad layer is not particularly limited, but is practically about 5 to 100 μm. Next, using polyimide having a higher refractive index than the material for the clad layer, a layer is similarly formed to form the core layer (3).
The thickness of the core layer is usually about 5 to 50 μm. Regarding the material used for the core layer (3) and the material used for the lower clad layer (2a), the core layer has a higher refractive index, and when the single mode is designed, the relative refractive index difference is about 0.3%. To be selected. A polyimide having such a relative refractive index difference can be easily obtained by selecting a raw material monomer.

Step (b) The laminated body of the lower clad layer and the core layer obtained in the step (a) is subjected to a dicing machine to leave a width to be a core and to reach both sides of the lower clad layer (2a). To cut. The dicing machine used here is shown in FIG. 2 (a), which is a perspective view of the schematic structure, and FIG.
As shown in the enlarged view of Fig. 0) with the blade attached, a disk-shaped blade (12) with a width of about 0.1 mm, in which diamond is fixed to the outer circumference of steel, is fixed to the spindle part with the flange (11), and the spindle part The positional relationship between the blade of the blade and the processing material on the sample stage can be determined by the spindle vertical feed table (13) and the forward and backward feed table (1
4) and the sample left and right feed table (15) can be adjusted in the Z direction, Y direction and X direction with high accuracy. As such a dicing machine, one already used for cutting a semiconductor substrate or the like can be diverted.

In this step, the dicing machine is used to perform grooving on the substrate formed in step (a). The grooving process is performed on the both sides of the substrate from the core layer (3) to the lower clad layer (2) while leaving a width to form a core with respect to the substrate.
Perform up to a). The width to form the core is usually about the same as the thickness of the core layer. The width of the groove depends on the width of the blade, but when the optical waveguides are formed in parallel, the optical signal propagating in each core may leak to the adjacent core if the width is too narrow. Due to the limitation due to the width of the disc-shaped blade, it is set to about 100 μm or more.

Step (c) A material having the same composition as the lower clad layer is provided as an upper clad layer (2b) on the upper surface and side surfaces of the core portion (3a) formed by cutting. By this process, the core part (3a)
Is embedded in the cladding layers (2a, 2b), and an optical waveguide is formed. The formation of the upper clad layer can be performed in the same manner as the layer formation in step (a). The thickness of the upper clad layer is about 5 to 100 μm from the upper surface of the core portion.

[0016]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited by the following description.

A polyimide varnish (manufactured by Hitachi Chemical Co., Ltd .: OPIN 1005 (50 cp)) was applied to a silicon wafer having a diameter of 3 inches by spin coating so that the thickness after heating and curing was 15 μm or more, and then the maximum temperature was 350 ° C. Was heat-treated for 2 hours to form a lower clad layer (refractive index 1.551 in the horizontal direction with respect to the substrate). Next, a polyimide varnish (OPIN1205 (50cp) manufactured by Hitachi Chemical Co., Ltd.) was applied on the lower clad layer by spin coating so that the thickness after heating and curing was 8 μm or more, and then the maximum temperature was 35.
A heat treatment was performed at 0 ° C. for 2 hours to form a core layer (refractive index of 1.556 in the horizontal direction with respect to the substrate).

Next, a 0.1 mm thick diamond blade (Osaka Diamond Co., Ltd .: DZCE0013NBC-Z2060) was attached to a dicing machine (Okamoto Machine Tool Co., Ltd .: AMD-6D), and a depth of 13 μm and a width of 8 μm from the surface of the core layer. The polyimide layer was cut so as to leave the core portion. Next, the same polyimide varnish used to form the lower clad layer was applied onto the core layer by spin coating so that the thickness after heating and curing was 8 μm or more, and the maximum temperature was 350 ° C. for 2 hours. A heat treatment was performed to embed the core portion, and an optical waveguide made of fluorinated polyimide was produced. Finally, the silicon wafer was made into chips by a dicing machine and the cut surface was polished. The optical propagation loss of this optical waveguide is 1.3 μm
It was 0.3 dB / cm when measured through polarized light in the horizontal direction with respect to the substrate.

[0019]

The present invention is a method for manufacturing an optical waveguide in which a core and a clad are made of polyimide, and a first polyimide layer on a substrate and a second polyimide having a higher refractive index than the first polyimide layer. After sequentially laminating the layers, using a dicing machine, the second polyimide layer is cut to reach the first polyimide layer leaving a width to be the core, then the first and the side and top of the core. The feature is that the same polyimide layer as the layer is provided. According to the present invention, an optical waveguide having a simple pattern such as a straight core pattern can be easily and economically manufactured using a dicing machine usually used in semiconductor-related facilities.

[Brief description of drawings]

FIG. 1 shows an optical waveguide forming process according to the present invention.

FIG. 2A is a perspective view showing an example of a dicing machine, and FIG. 2B is an enlarged view of a state in which a blade is attached to a spindle portion of the dicing machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2a, 2b Clad layer 3 Core layer 3a Core part 10 Spindle part 11 Flange 12 Blade 13 Spindle vertical feed table 14 Spindle longitudinal feed table 15 Spindle horizontal feed table

Claims (2)

[Claims] 1. A first polyimide layer and a second polyimide layer having a refractive index higher than that of the first polyimide layer are sequentially laminated on a substrate, and then the second polyimide layer is cored using a dicing machine. A method of manufacturing a polyimide-based optical waveguide characterized by cutting to a first polyimide layer leaving a width to be, and then providing the same polyimide layer as the first layer on the side part and the upper part of the core. . 2. The method for producing a polyimide optical waveguide according to claim 1, wherein the polyimide is a fluorinated polyimide.