JP2001242334A - Deformed polyimide optical waveguide and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deformed polyimide optical waveguide applicable to various optical wiring and branching circuits or to optical members containing a directional coupler. SOLUTION: In a buried type deformed polyimide optical waveguide which comprises a lower cladding layer, a core on the lower cladding layer and an upper cladding layer coating the lower cladding layer and the core, and of which the lower cladding layer, the core and the upper cladding layer are manufactured with a polyimide material, the deformed polyimide optical waveguide is characterized by the core having a rectangular section with a ratio of the core width to the core height >1 and <=2 and by the thickness of the lower cladding layer in a part where the core is not formed being in the >0% and <=30% range of the core height and thinner than that in a part where the core is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide using polyimide, and more particularly, to a low-loss buried type in which a waveguide mode becomes a single mode even when the ratio between the width and the height of a core is changed. The present invention relates to an 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. In addition, it is desired to establish an optical wiring technology for mounting these optical components at a high density, in particular, an optical waveguide forming technology.

In general, optical waveguides have (1) small optical loss, (2) easy manufacture, (3) small polarization dependence, and (4) a wide difference in the refractive index between the core and the clad. It is desired to have characteristics such as controllable in a range.
Conventionally, a low-loss optical waveguide using a quartz-based material has been studied. As demonstrated in optical fibers, quartz-based materials have very good light transmission,
Even in the case of a waveguide, 0.3 μm of light having a wavelength of 1.3 μm is used.
Low loss of 1 dB / cm or less has been achieved. However, since the quartz-based material has poor flexibility, it has to be manufactured on a substrate such as silicon and has a restriction that it must be used on the substrate. In addition, there is a problem in manufacturing that high-temperature treatment is required at the time of fabrication, and it is difficult to increase the area.

[0004] In order to solve the above-mentioned problems of quartz-based materials, polymer optical waveguides using materials such as polymethyl methacrylate (PMMA), polystyrene (PS), and polycarbonate (PC) have been studied. These polymer optical waveguides still have drawbacks, such as a lower heat resistance temperature and a larger light loss in the region on the longer wavelength side than the near-infrared region, as compared with quartz-based optical waveguides. However, molding is possible at a lower temperature and processing is easy, so that there are advantages that a reduction in cost can be expected and that it is advantageous for increasing the area. In addition, the present inventors have found that a polyimide-based polymer optical waveguide obtained by imparting heat resistance to a polymer material described in JP-A-4-9807 can be manufactured on a substrate.

[0005]

The cross-sectional shape of the core of a general communication single mode optical waveguide including the above-mentioned polyimide type optical waveguide is such that the waveguide mode is a single mode, and the mode field of the single mode fiber is Due to demands for matching the diameter and the dimensions of the core, a square section having a height and width of about 8 to 10 μm has been designed and manufactured. However, these optical waveguides can be connected to various optical wirings (high- or low-density, straight or curved, high-efficiency connection with a light exit surface or a good light incident surface having various shapes), or branch circuits and directionality. When applied to an optical component including a coupler, the cross-sectional shape of the optical waveguide needs to be a vertically long or horizontally long shape other than a square.

[0006] Polymeric optical waveguides generally comprise laminating a uniform core layer over a lower cladding layer, etching the core layer to form a patterned core, and forming the core and lower cladding layer. Is formed by laminating an upper cladding layer covering the substrate. When the core pattern is formed by etching in this manner, the vicinity of the end point of the etching (that is, the bottom surface exposed by the etching and the lower portion of the core sidewall).
Has a complicated shape effect such as surface roughness due to etching, vertical defects on the core side wall, and cracks, and becomes a problem when high-precision verticality and uniformity are required on the side surfaces of the core. In addition, when the positional stability of the core is particularly important, how to improve the positional stability of the core is a problem.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors diligently studied the structural design of an optical waveguide and invented a modified polyimide optical waveguide having the following cross-sectional structure. It has been found that single-mode waveguide with loss can be realized.

Further, in the modified polyimide waveguide of the present invention, by making the etching depth of the core pattern larger than the thickness of the core layer, a defective interface based on surface roughness of the etching upper surface or a side surface of the core generated at the time of etching. Cracks and the like in the lower clad layer near the core can be kept away from the core to achieve highly accurate perpendicularity and uniformity on the side surface of the core, and performance degradation due to the crack can be suppressed.

Furthermore, in the modified polyimide waveguide of the present invention, the etching depth of the core pattern is made smaller than the thickness of the core layer, thereby improving the positional stability of the core portion and the distortion (stress) accompanying the production of the optical waveguide. ) Can be suppressed.

A buried type irregular shaped polyimide optical waveguide according to a first embodiment of the present invention comprises a lower cladding layer, a core on the lower cladding layer, an upper cladding layer covering the lower cladding layer and the core. , The lower cladding layer,
The core, and the upper cladding layer are made of a polyimide material, the core has a rectangular cross-section having a ratio of core width to core height of greater than 1 and less than or equal to 2, and The thickness of the lower cladding layer in the portion where the core is not formed is smaller than the thickness of the lower cladding layer in the portion where the core is formed within a range of more than 0% and not more than 30% of the core height. It is characterized by.

A buried type irregular shaped polyimide optical waveguide according to a second embodiment of the present invention comprises a lower cladding layer, a core on the lower cladding layer, an upper cladding layer covering the lower cladding layer and the core. , The lower cladding layer,
The core, and the upper cladding layer are made of a polyimide material, the core has a rectangular cross-section having a ratio of core width to core height of greater than 1 and less than or equal to 2, and The thickness of the lower cladding layer in the portion where the core is not formed is equal to the thickness of the lower cladding layer in the portion where the core is formed.

An embedded polyimide optical waveguide according to a third embodiment of the present invention comprises a lower clad layer, a core layer having a projection on the lower clad layer, and covering the lower clad layer and the core layer. Consisting of an upper cladding layer,
The protrusion and the core layer below the protrusion are used as a core, and the lower clad layer, the core layer, and the upper clad layer are made of a polyimide material. The core layer has a rectangular cross section in which the height ratio is greater than 1 and less than or equal to 2 and the portion of the core layer where the protrusions are not formed has a thickness greater than 0% of the core height and 30% or less.
% Or less.

A buried type modified polyimide optical waveguide according to a fourth embodiment of the present invention comprises a lower cladding layer, a core on the lower cladding layer, an upper cladding layer covering the lower cladding layer and the core. , The lower cladding layer,
The core, and the upper cladding layer are made of a polyimide material, the core has a square cross section having a core width to core height ratio of 1, and a portion where the core is not formed. Is characterized in that the thickness of the lower cladding layer is smaller than the thickness of the lower cladding layer in the portion where the core is formed, within a range of more than 0% and not more than 30% of the core height.

A buried-type modified polyimide optical waveguide according to a fifth embodiment of the present invention includes a lower cladding layer, a core layer having a projection on the lower cladding layer, and covering the lower cladding layer and the core layer. Consisting of an upper cladding layer,
The protrusion and the core layer below the protrusion are used as a core, and the lower clad layer, the core layer, and the upper clad layer are made of a polyimide material. It has a square cross section having a height ratio of 1, and the thickness of the core layer in a portion where the protrusion is not formed is larger than 0% and 30% or less of the core height. And

A buried type irregular shaped polyimide optical waveguide according to a sixth embodiment of the present invention comprises a lower cladding layer, a core on the lower cladding layer, an upper cladding layer covering the lower cladding layer and the core. , The lower cladding layer,
The core, and the upper cladding layer are made of a polyimide material, wherein the core has a rectangular cross section having a ratio of core width to core height of 0.7 or more and less than 1, and The thickness of the lower cladding layer in the portion where the core is not formed is smaller than the thickness of the lower cladding layer in the portion where the core is formed within a range of more than 0% and not more than 30% of the height of the core. It is characterized by the following.

A buried type irregularly shaped polyimide optical waveguide according to a seventh embodiment of the present invention comprises a lower cladding layer, a core on the lower cladding layer, an upper cladding layer covering the lower cladding layer and the core. , The lower cladding layer,
The core, and the upper cladding layer are made of a polyimide material, wherein the core has a rectangular cross section having a ratio of core width to core height of 0.7 or more and less than 1, and The thickness of the lower cladding layer in the portion where the core is not formed is equal to the thickness of the lower cladding layer in the portion where the core is formed.

An embedded polyimide optical waveguide according to an eighth embodiment of the present invention comprises a lower clad layer, a core layer having a projection on the lower clad layer, and covering the lower clad layer and the core layer. Consisting of an upper cladding layer,
The protrusion and the core layer below the protrusion are used as a core, and the lower clad layer, the core layer, and the upper clad layer are made of a polyimide material. The core layer has a rectangular cross section having a height ratio of 0.7 or more and less than 1, and the thickness of the core layer where the protrusions are not formed is greater than 0% and 30% or less of the core height. There is a feature.

In the buried type modified polyimide optical waveguide according to the first to eighth embodiments of the present invention, the polyimide material is a fluorine-containing polyimide comprising a repeating unit represented by any one of formulas (1) to (3): Formula (1)-
It may be selected from the group consisting of a fluorinated polyimide copolymer comprising two or three types of repeating units selected from (3), and a mixture thereof.

[0019]

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[0020]

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[0021]

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A method for manufacturing a modified polyimide optical waveguide according to a ninth embodiment of the present invention includes the steps of laminating a lower clad layer and a core layer, and forming a core by etching the core layer. The core has a rectangular cross-section where the ratio of core width to core height is greater than 1 and less than or equal to 2, and the etching depth of the core layer is 100 times the core layer height.
% And 130% or less, and a step of laminating an upper cladding layer, wherein the lower cladding layer, the core layer and the upper cladding layer are manufactured using a polyimide material.

A method for manufacturing a modified polyimide optical waveguide according to a tenth embodiment of the present invention includes a step of laminating a lower clad layer and a core layer, and a step of forming a core by etching the core layer. The core has a rectangular cross-section with a core width to core height ratio of greater than 1 and less than or equal to 2;
And the etching depth of the core layer includes a step equal to the height of the core layer, and a step of laminating an upper clad layer, wherein the lower clad layer, the core layer and the upper clad layer are manufactured using a polyimide material. It is characterized by the following.

A method for manufacturing a modified polyimide optical waveguide according to an eleventh embodiment of the present invention includes a step of laminating a lower clad layer and a core layer, and a step of etching the core layer to form a core. The core has a rectangular cross-section with a core width to core height ratio of greater than 1 and less than or equal to 2;
And the etching depth of the core layer is 70 times the height of the core layer.
% And less than 100%, and a step of laminating an upper cladding layer, wherein the lower cladding layer, the core layer and the upper cladding layer are manufactured using a polyimide material.

A method for manufacturing a modified polyimide optical waveguide according to a twelfth embodiment of the present invention includes a step of laminating a lower clad layer and a core layer, and a step of forming a core by etching the core layer. Said core having a square cross-section with a core width to core height ratio of 1 and an etching depth of said core layer being greater than 100% and not more than 130% of the core layer height; Laminating an upper cladding layer, wherein the lower cladding layer, the core layer and the upper cladding layer are manufactured using a polyimide material.

A method of manufacturing a modified polyimide optical waveguide according to a thirteenth embodiment of the present invention includes a step of laminating a lower clad layer and a core layer, and a step of forming a core by etching the core layer. A step in which the core has a square cross section having a ratio of core width to core height of 1 and an etching depth of the core layer is 70% or more and less than 100% of a height of the core layer; Laminating the layers, wherein the lower cladding layer, the core layer and the upper cladding layer are manufactured using a polyimide material.

A method for manufacturing a modified polyimide optical waveguide according to a fourteenth embodiment of the present invention comprises the steps of laminating a lower cladding layer and a core layer, and forming a core by etching the core layer. The core has a rectangular cross-section having a ratio of core width to core height of 0.7 or more and less than 1, and an etching depth of the core layer is greater than 100% and 130% or less of the height of the core layer. And a step of laminating an upper clad layer, wherein the lower clad layer, the core layer and the upper clad layer are produced using a polyimide material.

A method for manufacturing a modified polyimide optical waveguide according to a fifteenth embodiment of the present invention includes a step of laminating a lower clad layer and a core layer, and a step of etching the core layer to form a core. The core has a rectangular cross section having a ratio of core width to core height of 0.7 or more and less than 1, and an etching depth of the core layer is equal to the height of the core layer. And forming the lower cladding layer, the core layer and the upper cladding layer using a polyimide material.

A method for manufacturing a modified polyimide optical waveguide according to a sixteenth embodiment of the present invention includes a step of laminating a lower clad layer and a core layer, and a step of forming a core by etching the core layer. The core has a rectangular cross section having a ratio of core width to core height of 0.7 or more and less than 1, and the etching depth of the core layer is 70% or more and less than 100% of the core layer height. And a step of laminating an upper clad layer, wherein the lower clad layer, the core layer, and the upper clad layer are manufactured using a polyimide material.

In the method for manufacturing a modified polyimide optical waveguide according to the ninth to sixteenth embodiments of the present invention, the polyimide material comprises a fluorine-containing repeating unit represented by any one of formulas (1) to (3). Polyimide, Formula (1)
It may be selected from the group consisting of a fluorinated polyimide copolymer consisting of two or three kinds of repeating units selected from (3) and a mixture thereof.

[0031]

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[0032]

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[0033]

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[0034]

BEST MODE FOR CARRYING OUT THE INVENTION As the polyimide material used in the present invention, from the viewpoint of light transmittance, a fluorine-containing polyimide having particularly excellent light transmittance is preferable. Specific examples of the polyimide include a polyimide synthesized from an acid dianhydride or chloride, which is the following tetracarboxylic acid or a derivative thereof, and a diamine.

Examples of tetracarboxylic acids include pyromellitic acid, trifluoromethylpyromellitic 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'-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′-tetracarboxydiphenyl, 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-tetracarboxyperylene, 2,
2-bis {4- (3,4-dicarboxyphenoxy) phenyl} propane, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, 2,2-bis {4- (3,4-dicarboxyphenoxy) phenyl} hexa Fluoropropane, bis (trifluoromethyl) dicarboxyphenoxy diphenyl, 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, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene, 1,4-bis (3,4-
4-dicarboxytrifluorophenoxy) octafluorobiphenyl, 1,4-difluoropyromellitic acid,
1-trifluoromethyl-4-fluoropyromellitic acid, 1,4-di (trifluoromethyl) pyromellitic acid,
1-pentafluoroethyl-4-fluoropyromellitic acid, 1-pentafluoroethyl-4-trifluoromethylpyromellitic acid, 1,4-di (pentafluoroethyl)
Pyromellitic acid, 1-pentafluorophenyl-4-fluoropyromellitic acid, 1-pentafluorophenyl-
4-trifluoromethylpyromellitic acid, 1-pentafluorophenyl-4-pentafluoroethylpyromellitic acid, 1,4-di (pentafluorophenyl) pyromellitic acid, 1-trifluoromethoxy-4-fluoropyromellitic acid , 1-trifluoromethoxy-4-trifluoromethylpyromellitic acid, 1-trifluoromethoxy-
4-pentafluoroethyl pyromellitic acid, 1-trifluoromethoxy-4-pentafluorophenylpyromellitic acid, 1,4-di (trifluoromethoxy) pyromellitic acid, 1-pentafluoroethoxy-4-fluoropyromellitic acid , 1-pentafluoroethoxy-4-trifluoromethylpyromellitic acid, 1-pentafluoroethoxy-4-pentafluoroethylpyromellitic acid, 1-
Pentafluoroethoxy-4-pentafluorophenylpyromellitic acid, 1-pentafluoroethoxy-4-trifluoromethoxypyromellitic acid, 1,4-di (pentafluoroethoxy) pyromellitic acid, 1-pentafluorophenoxy-4- Fluoropyromellitic acid, 1-pentafluorophenoxy-4-trifluoromethylpyromellitic acid, 1-pentafluorophenoxy-4-pentafluoroethylpyromellitic acid, 1-pentafluorophenoxy-4-pentafluorophenylpyromellitic acid, 1-pentafluorophenoxy-4-trifluoromethoxypyromellitic acid, 1-pentafluorophenoxy-4-pentafluoroethoxypyromellitic acid,
4-di (pentafluorophenoxy) pyromellitic acid, hexafluoro-3,3 ', 4,4'-biphenyltetracarboxylic acid, hexafluoro-3,3', 4,4'-biphenylethertetracarboxylic acid, hexa Fluoro-3,3 ',
4,4'-benzophenonetetracarboxylic acid, bis (3,
4-dicarboxytrifluorophenyl) sulfone, bis (3,4-dicarboxytrifluorophenyl) sulfide, bis (3,4-dicarboxytrifluorophenyl) difluoromethane, 1,2-bis (3,4-di (Carboxytrifluorophenyl) tetrafluoroethane,
2,2-bis (3,4-dicarboxytrifluorophenyl) hexafluoropropane, 1,4-bis (3,4-dicarboxytrifluorophenyl) tetrafluorobenzene, 3,4-dicarboxytrifluorophenyl-
3 ', 4'-dicarboxytrifluorophenoxy-difluoromethane, bis (3,4-dicarboxytrifluorophenoxy) difluoromethane, 1,2-bis (3,4
-Dicarboxytrifluorophenoxy) tetrafluoroethane, 2,2-bis (3,4-dicarboxytrifluorophenoxy) hexafluoropropane, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene 2,2,3,6,7-tetracarboxy-tetrafluoronaphthalene, 2,3,6,7-tetracarboxy-hexafluoroanthracene, 2,3,6,
7-tetracarboxy-hexafluorophenanthrene, 2,3,6,7-tetracarboxy-tetrafluorobiphenylene, 2,3,7,8-tetracarboxy-tetrafluorodibenzofuran, 2,3,6,7-tetracarboxy- Tetrafluoroanthraquinone, 2,3,6,7
-Tetracarboxy-pentafluoroanthrone, 2,
3,7,8-tetracarboxy-tetrafluorophenoxathiin, 2,3,7,8-tetracarboxy-tetrafluorothianthrene, 2,3,7,8-tetracarboxy-tetrafluorodibenzo [b, e] 1,4 dioxane and the like can be mentioned.

Examples of the diamine include 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, 1
H-perfluoro-1-heptanoxy) -1,3-diaminobenzene, 4- (1H, 1, H-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-
Dodecanoloxy) -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, 3,3'-bis (trifluoromethyl)-
4,4'-diaminobiphenyl, 4,4'-oxydianiline, 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) hexafluoro Propane, 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 ′ ″-diamino-p-quarterphenyl, 4,4′-
Bis (p-aminophenoxy) biphenyl, 2,2-bis {4- (p-aminophenoxy) phenyl} propane,
4,4'-bis (3-aminophenoxyphenyl) diphenyl sulfone, 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} hexafluoro Propane, 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-amino Phenyl) diethylsilane, tetrafluoro-1,2-phenylenediamine, tetrafluoro-1,3-phenylenediamine, tetrafluoro-1,4-phenylenediamine, hexafluoro-1,5-diaminonaphthalene, hexafluoro-2, 6-diaminonaphthalene, 3-trifluoromethyl-trifluoro-1,2-phenylenediamine, 4-
Trifluoromethyl-trifluoro-1,2-phenylenediamine, 2-trifluoromethyl-trifluoro-
1,3-phenylenediamine, 4-trifluoromethyl-trifluoro-1,3-phenylenediamine, 5-trifluoromethyl-trifluoro-1,3-phenylenediamine, 2-trifluoromethyl-trifluoro-
1,4-phenylenediamine, 3,4-bis (trifluoromethyl) -difluoro-1,2-phenylenediamine,
3,5-bis (trifluoromethyl) -difluoro-1,2
-Phenylenediamine, 2,4-bis (trifluoromethyl) -difluoro-1,3-phenylenediamine, 4.5
-Bis (trifluoromethyl) -difluoro-1,3-phenylenediamine, 4,6-bis (trifluoromethyl)
-Difluoro-1,3-phenylenediamine, 2,3-bis (trifluoromethyl) -difluoro-1,4-phenylenediamine, 2,5-bis (trifluoromethyl) -difluoro-1,4-phenylenediamine, 3,4,5-tris
(Trifluoromethyl) -fluoro-1,2-phenylenediamine, 3,4,6-tris (trifluoromethyl) -fluoro-1,2-phenylenediamine, 2,4,5-tris (trifluoromethyl)- Fluoro-1,3-phenylenediamine,
2,4,6-tris (trifluoromethyl) -fluoro-1,3-
Phenylenediamine, 4,5,6-tris (trifluoromethyl) -fluoro-1,3-phenylenediamine, tetrakis
(Trifluoromethyl) -1,2-phenylenediamine,
Tetrakis (trifluoromethyl) -1,3-phenylenediamine, tetrakis (trifluoromethyl) -1,4-
Phenylenediamine, 3-pentafluoroethyl-trifluoro-1,2-phenylenediamine, 4-pentafluoroethyl-trifluoro-1,2-phenylenediamine, 2-pentafluoroethyl-trifluoro-1,
3-phenylenediamine, 4-pentafluoroethyl-
Trifluoro-1,3-phenylenediamine, 5-pentafluoroethyl-trifluoro-1,3-phenylenediamine, 2-pentafluoroethyl-trifluoro-
1,4-phenylenediamine, 3-trifluoromethoxy-trifluoro-1,2-phenylenediamine, 4-
Trifluoromethoxy-trifluoro-1,2-phenylenediamine, 2-trifluoromethoxy-trifluoro-1,3-phenylenediamine, 4-trifluoromethoxy-trifluoro-1,3-phenylenediamine,
5-trifluoromethoxy-trifluoro-1,3-phenylenediamine, 2-trifluoromethoxy-trifluoro-1,4-phenylenediamine, 3,3′-diamino-octafluorobiphenyl, 3,4′-diamino- Octafluorobiphenyl, 4,4'-diamino-octafluorobiphenyl, 2,2'-bis (trifluoromethyl)
-4,4'-diaminohexafluorobiphenyl, 3,3 '
-Bis (trifluoromethyl) -4,4'-diaminohexafluorobiphenyl, bis (3-amino-tetrafluorophenyl) ether, 3,4'-diamino-octafluorobiphenyl ether, bis (4-amino-tetrafluoro Phenyl) ether, 3,3'-diamino-octafluorobenzophenone, 3,4'-diamino-octafluorobenzophenone, 4,4'-diamino-octafluorobenzophenone, bis (3-amino-tetrafluorophenyl) sulfone, 3 , 4'-diamino-octafluorobiphenyl sulfone, bis (4-amino-tetrafluorophenyl) sulfone, bis (3-amino-tetrafluorophenyl) sulfide, 3,4'-diamino-octafluorobiphenyl sulfide, bis (4 -Amino-tetrafluorophenyl L) sulfide, bis (4-aminotetrafluorophenyl) difluoromethane,
2-bis (4-aminotetrafluorophenyl) tetrafluoroethane, 2,2-bis (4-aminotetrafluorophenyl) hexafluoropropane, 4,4 "-diamino-dodecafluoro-p-terphenyl, 4-amino −
Tetrafluorophenoxy-4′-amino-tetrafluorophenyl-difluoromethane, bis (4-amino-
(Tetrafluorophenoxy) -difluoromethane, 1,2
-Bis (4-amino-tetrafluorophenoxy) -tetrafluoroethane, 2,2-bis (4-amino-tetrafluorophenoxy) -hexafluoropropane, 1,4-
Bis (4-amino-tetrafluorophenoxy) -tetrafluorobenzene, 2,6-diamino-hexafluoronaphthalene, 2,6-diamino-octafluoroanthracene, 2,7-diamino-octafluorophenanthrene, 2,6-diamino -Hexafluorobiphenylene, 2,7-diamino-hexafluorodibenzofuran, 2,6-diamino-hexafluoroanthraquinone, 2,6-diamino-octafluoroanthrone, 2,
7-diamino-hexafluorophenoxathiin, 2,
7-diamino-hexafluorothianthrene and the like can be mentioned.

Among the polyimides synthesized by combining the above tetracarboxylic acid or its derivative with a diamine, the following polyimides are used as optical waveguide materials from the viewpoint of exhibiting excellent light transmittance and refractive index controllability. Is preferred. (1) pyromellitic dianhydride (PMDA) and 2,
Using two kinds of acid dianhydrides of 2-bis (3,4-dicarboxydiphenyl) hexafluoropropane dianhydride (6FDA) as tetracarboxylic acid derivatives, 2,2′-
Fluorine-containing polyimide copolymer using bis (trifluoromethyl) -4,4′-diaminodiphenyl (TFDB) as a diamine; (2) using one of PMDA or 6FDA as a tetracarboxylic acid derivative;
Homopolyimide of homopolymer using DB as diamine, (3) using 6FDA as tetracarboxylic acid,
A fluorine-containing polyimide copolymer using two kinds of FDB and 4,4'-oxydianiline (ODA) as a diamine, and (4) a homopolyimide of a homopolymer synthesized from 6FDA and ODA.

Further, the polyimide used in the present invention may be a polyimide mixture in addition to the copolymer. The polyimide mixture can be synthesized via a mixture of a polyamic acid solution that is a polyimide precursor.

Next, a method of manufacturing a buried type irregular shaped polyimide optical waveguide of the present invention will be described with reference to FIG. FIG. 1 shows a method for manufacturing a modified polyimide waveguide of the present invention in which the core width is larger than the core height and the etching depth for forming the core is larger than the thickness of the core layer. FIG.
Reference numeral 1 denotes a substrate, reference numeral 2 denotes a lower cladding layer,
Reference numeral 3 denotes a core layer, reference numeral 4 denotes a mask layer for forming a core pattern, reference numeral 5 denotes a resist layer, and reference numeral 6 denotes an upper cladding layer.

A polyimide material for a lower cladding layer (or a polyamic acid solution as a precursor thereof) is applied on a substrate 1 such as silicon by a method such as spin coating, and is cured by heating or the like. Form a layer. As the substrate 1, a material that has excellent surface smoothness and can withstand heat treatment for forming polyimide can be used. Preferred materials for the substrate 1 include a silicon wafer, a metal plate such as aluminum, stainless steel or steel,
It includes a heat-resistant resin substrate such as polyimide, a glass substrate, a ceramic substrate, or the like. Among these materials, a silicon wafer is a preferable material in consideration of surface smoothness, excellent heat resistance and low cost.

Next, as shown in FIG. 1A, the core layer 3 is formed using a polyimide material having a higher refractive index than the polyimide material for the lower cladding layer. As a method for forming the core layer 3, the same method as that for forming the lower clad layer 2 can be used. Further, a mask layer 4 for obtaining a core pattern is formed on the core layer 3. As the mask layer, a metal such as aluminum or titanium, Si
O ₂ , spin-on-glass (SOG), Si-containing resist, photosensitive polyimide, or the like can be used.

After the formation of the mask layer 4, the steps of resist coating, pre-baking, exposure, development, and after-baking are performed to obtain a patterned resist layer 5 as shown in FIG. At this time, by making the width of the patterned resist layer larger than the thickness of the core layer 3, a core having a core width larger than the core height can be formed. The core width (ie, the width of the resist layer) should be greater than one time the core height (ie, the thickness of the core layer) and no greater than two (ie, the ratio of the core width to the core height should be greater than 1 and 2) The following is preferred).

Next, as shown in FIG. 1C, the mask layer 4 not protected by the resist layer 5 is removed by etching. At this time, when a Si-containing resist or a thick photosensitive polyimide is used as the mask layer 4,
Since patterning can be performed using these materials, there is no need to provide the resist layer 5.

Then, as shown in FIG. 1D, the resist layer 5 and the mask layer 4 formed by patterning as described above are used as an etching mask, and the core layer 3 not protected by the etching mask is used. Is removed by dry etching to form a patterned core. At this time, by setting the depth of the dry etching to be larger than the thickness of the core layer 3, a part of the lower cladding layer is also etched away.

Next, as shown in FIG. 1E, the remaining mask layer 4 is removed by dry etching or using a stripping solution. Then, as shown in FIG. 1F, the upper cladding layer 6 is formed using a polyimide material having a smaller refractive index than the polyimide material used as the core layer.
To form The method of forming the lower cladding layer 2
Can be used in the same manner as the method for forming

Through the above steps, a buried-type modified polyimide optical waveguide can be manufactured. Further, by removing the substrate from the embedded optical waveguide formed on the substrate and performing heat treatment as necessary, as shown in FIG. 1 (g). An embedded polyimide film optical waveguide having a core width larger than the core height and an etching depth smaller than the core height can be manufactured.

By partially changing the manufacturing method described above, it is possible to manufacture modified polyimide optical waveguides having various structures. When it is desired to make the core width and the core height the same, the width of the resist layer 5 or the mask layer 4 to be patterned may be made the same as the height of the core layer 3, or the core height may be made larger than the core width. If you want to increase it,
The width of the resist layer 5 or the mask layer 4 may be smaller than the height of the core layer 3. That is, the core width is arbitrarily selected depending on the design of the photomask (specifically, the width of the resist layer 5 or the width of the mask layer 4 when a Si-containing resist or photosensitive polyimide is used as the mask layer 4). can do.

When it is desired to make the etching depth of the core layer the same as the height of the core, the etching amount of the core layer may be made the same as the thickness of the core layer, and the etching depth of the core layer may be made the same. If the height is to be smaller than the height, the etching amount of the core layer may be set to be smaller than the thickness of the core layer. Further, the etching amount of the core layer is determined by the product of the etching rate of the core layer and the etching time.
Therefore, if the etching rate of the core layer is determined in advance, the etching amount of the core layer can be controlled by the etching time.

When the core layer 3 is formed by spin coating, the core height (ie, the thickness of the core layer)
Can be controlled by the number of rotations of the spin coat and the like. By appropriately setting the various parameters described above (photomask design, etching amount, core layer thickness, etc.), various structures as shown in FIGS. 2A to 2H can be obtained. A modified polyimide optical waveguide can be made.

FIGS. 2A to 2C show modified polyimide optical waveguides in which the core width w is larger than the core height h. By setting the ratio of the core width to the core height (w / h) to be greater than 1 and 2 or less, a low-loss single-mode optical waveguide could be obtained. FIGS. 2D to 2F show modified polyimide optical waveguides in which the core width is larger than the core height. By setting the ratio of the core width to the core height to be 0.7 or more and less than 1, a low-loss single-mode optical waveguide could be obtained. For example, the core height h is 7 μm, and the core width w is 4.9 μm, 6.3 μm, 7.7 μm, 8.4 μm
And 14.0 μm, the ratio of the core width to the core height is 0.7, 0.9, respectively.
Optical waveguides having a 1.2 and 2.0 long core cross section can be formed, and each of these optical waveguides having a core cross section has low loss and functions as a single mode waveguide.

From the viewpoint of the core height and the etching depth, FIGS. 2A, 2D and 2F show a modified polyimide optical waveguide having a larger etching depth than the core height. When the etching depth is made larger than the core height as described above, the etching depth is set to 10 times the core height.
It is preferable to be larger than 0% and 130% or less. That is, the thickness of the lower clad layer in the portion where the core is not formed is larger than 0% and 30% or less of the core height, and is smaller than the thickness of the lower clad layer in the portion where the core is formed. thin. By making the etching depth larger than the core height in this manner, the etching end point can be moved away from the core, and various shape effects at the etching end point, that is, a defective interface based on surface roughness of the etching upper surface and a core generated at the time of etching. Cracks on the side of the side can be kept away from the core. Accordingly, highly accurate verticality and uniformity of the core side surface can be achieved, and performance degradation due to the effect of the etching end point can be suppressed.

On the other hand, FIGS. 2 (c), (e) and (h)
Is a modified polyimide optical waveguide having a core height larger than the etching depth, that is, a modified polyimide optical waveguide having a core layer having a protrusion. When the core height (that is, the thickness of the core layer) is larger than the etching depth as described above, the etching depth is set to 7 times the core height.
The core height is preferably 0% or more and less than 100%, and more preferably 90% or more and less than 100% of the core height so as not to impair the effect of confining guided light. That is, the thickness of the core layer other than the protrusions is 0% of the core height.
Greater than 30%, more preferably 0% of core height
Greater than 10%. By making the core height larger than the etching depth in this way, it is possible to improve the positional stability of the core portion and to suppress the performance deterioration caused by distortion (stress generation) accompanying the fabrication of the optical waveguide. In this case, the rectangular region 11 including the protrusion and the core layer below the protrusion functions as a core.

When the ratio of the core width to the core height or the etching depth is out of the above range, not only the single mode waveguide of the optical waveguide becomes difficult, but also the TE mode or the T mode.
This causes an increase in the loss in the M mode or an increase in the difference between the loss in the TE mode and the loss in the TM mode (polarization-dependent loss).

[0054]

EXAMPLES The present invention will be described in more detail with reference to several examples. It should be noted that it is clear that countless modified polyimide optical waveguides can be obtained by combining various polyimide copolymers and mixtures, or by differences in optical waveguide structures, and the present invention is limited to only these examples. It should be understood that it is not.

The shape of the core of the manufactured optical waveguide was confirmed using an optical microscope. Further, the waveguide mode and the loss of the manufactured optical waveguide were measured as follows. First, from the incident end, polarized light (TE mode light) in a direction parallel to the 1.3 μm wavelength waveguide film surface and polarized light (TM mode light) in a direction perpendicular to the 1.3 μm wavelength waveguide film surface.
Was incident. The waveguide mode was determined by measuring the intensity distribution (near field mode pattern) of the light emitted from the optical waveguide. Further, the difference in intensity between the incident light and the output light was divided by the length of the optical waveguide to determine the light loss per unit length.

(Example 1) 2,4-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2 '
Polyimide synthesized from -bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFDB) (6
15 of polyamic acid which is a precursor of FDA / TFDB)
A mass% dimethylacetamide (DMAc) solution was applied by spin coating. This coating film was heated and imidized in an inert oven in a dry nitrogen gas atmosphere to form a lower cladding layer made of polyimide (6FDA / TFDB).

Then, 15 mol% of pyromellitic dianhydride (PMDA) and 35 mol% of
Polyamic acid 15 which is a precursor of a polyimide copolymer synthesized from 6FDA and 50 mol% of TFDB (a polyimide copolymer composed of 30 mol% of PMDA / TFDB and 70 mol% of 6FDA / TFDB) Mass% D
The MAc solution was applied by a spin coating method. This coating film was heated and imidized in an inert oven in a dry nitrogen gas atmosphere to form a 7.1 μm thick core layer.

Next, an aluminum layer (mask layer) having a thickness of 0.3 μm was deposited on the core layer. Then, a positive photoresist was applied to the aluminum layer by spin coating, and then prebaked at about 95 ° C. Next, after irradiating ultraviolet rays using a photomask for pattern formation and an ultra-high pressure mercury lamp, development was performed using a developer for a positive resist, and post-baking was performed at 135 ° C. Thus, a resist layer having a linear pattern having a line width of 10.3 μm was formed.

Next, the exposed aluminum was removed by wet etching, and the resist pattern was transferred to an aluminum layer. Further, using the aluminum layer having the transferred pattern as a mask, the polyimide of the core layer and the lower cladding layer from the upper surface of the core layer to a depth of 9.0 μm was removed by dry etching using oxygen plasma. Then, aluminum used as a mask remaining on the core layer was removed using an etchant.

Then, a 15% by mass DMAc solution of a polyamic acid, which is the same precursor as the polyimide (6FDA / TFDB) for the lower cladding layer, was applied by spin coating. This coating film was heated and imidized in an inert oven in a dry nitrogen gas atmosphere to form an upper clad layer. Finally, both ends of the optical waveguide were cut off with a dicing saw to form light input / output end faces.

In this way, as shown in FIG. 2A, a buried type variant having a ratio of the core width w to the core height h of 1.45 and an etching depth of 127% of the core height. A polyimide optical waveguide was obtained. The thickness of the lower cladding layer in the portion where the core 3 is not formed is 27% of the core height than the lower cladding layer in the portion where the core 3 is formed.
(1.9 μm) Thin. The guided light in the TE mode of the optical waveguide was a single mode. Further, the loss in the TE mode and the TM mode of this optical waveguide is 1.0
dB / cm or less, and the polarization dependent loss is 0.5 dB / c.
m or less.

Example 2 As materials for forming a core layer, 50 mol% of 6FDA, 12.5 mol% of 4,4'-oxydianiline (ODA) and 37.5 mol% of TFDB
25 mol% of 6FDA / ODA and 75 mol% of 6FDA using a DMAc solution of a polyamic acid synthesized from
A core layer made of a polyimide copolymer with DA / TFDB was formed, the core height (core layer thickness) was set to 8.0 μm, the line width was set to 11.5 μm, and the etching depth was set to 9.1.
An optical waveguide was formed by repeating the method of Example 1 except that the thickness was set to μm.

In this manner, as shown in FIG. 2A, a buried type variant having a ratio of the core width w to the core height h of 1.44 and an etching depth of 114% of the core height is used. A polyimide optical waveguide was obtained. The guided light in the TE mode of the optical waveguide was a single mode. The loss in the TE mode and the TM mode of the optical waveguide is as follows.
Both are 1.0 dB / cm or less, and the polarization dependent loss is 0.1 dB / cm.
It was 5 dB / cm or less.

Example 3 A polyamic acid DMAc synthesized from 50 mol% of 6FDA, 10 mol% of ODA and 40 mol% of TFDB as a material for forming a core layer
Using the solution, a core layer made of a polyimide copolymer of 20 mol% of 6FDA / ODA and 80 mol% of 6FDA / TFDB was formed, and the core height (core layer thickness) was set to 8.
An optical waveguide was formed by repeating the method of Example 1 except that the line width was 0 μm, the line width was 8.8 μm, and the etching depth was 8.0 μm.

In this manner, as shown in FIG. 2B, a buried type irregularly shaped polyimide optical waveguide having a core width w / core height h ratio of 1.10 and an etching depth equal to the core height is obtained. Obtained. The guided light in the TE mode of the optical waveguide was a single mode. The loss in the TE mode and the TM mode of this optical waveguide is 1.
0 dB / cm or less, and the polarization dependent loss is 0.5 dB / cm.
cm or less.

Example 4 As a material for forming a core layer, DMAc of a polyamic acid synthesized from 50 mol% of 6FDA, 20 mol% of ODA and 30 mol% of TFDB was used.
Using the solution, a core layer made of a polyimide copolymer of 40 mol% of 6FDA / ODA and 60 mol% of 6FDA / TFDB was formed, and the core height (core layer thickness) was set to 7.
An optical waveguide was formed by repeating the method of Example 1 except that the line width was 0 μm, the line width was 12.0 μm, and the etching depth was 6.3 μm.

In this way, as shown in FIG. 2C, the buried-type variant having the ratio of the core width w to the core height h of 1.71 and the etching depth of 90% of the core height is used. A polyimide optical waveguide was obtained. That is, the thickness of the core layer 3 other than the core portion 11 is 10% (0.7 μm) of the core height.
m). The guided light in the TE mode of this optical waveguide is
It was single mode. The loss in the TE mode and the TM mode of this optical waveguide is 1.0 dB / c.
m or less, and the polarization dependent loss was 0.5 dB / cm or less.

Example 5 As a material for forming the lower cladding layer and the upper cladding layer, a DMAc solution of a polyamic acid synthesized from 50 mol% of 6FDA, 20 mol% of ODA and 30 mol% of TFDB was used. , 40 mol% 6FDA / ODA and 60 mol% 6FDA / TFD
An upper clad layer and a lower clad layer made of a polyimide copolymer with B are formed, the core height (core layer thickness) is set to 8.0 μm, the line width is set to 8.8 μm, and the etching depth is set to 7.2 μm. An optical waveguide was formed by repeating the method of Example 1 except that the above method was adopted.

In this way, as shown in FIG. 2C, the buried-type variant having the ratio of the core width w to the core height h of 1.10 and the etching depth of 90% of the core height is used. A polyimide optical waveguide was obtained. The guided light in the TE mode of the optical waveguide was a single mode. The loss in the TE mode and the TM mode of the optical waveguide is 1.0 dB / cm or less, and the polarization dependent loss is 0.5 dB / cm.
It was less than dB / cm.

Example 6 As a material for forming the lower clad layer and the upper clad layer, a DMAc solution of a polyamic acid synthesized from 50 mol% of 6FDA, 5 mol% of ODA and 45 mol% of TFDB was used. , 10 mol%
6FDA / ODA and 90 mol% 6FDA / TFDB
And an upper clad and a lower clad layer made of a polyimide copolymer having a core height (core layer thickness) of 8.3 μm, a line width of 8.3 μm, and an etching depth of 9.1 μm. An optical waveguide was formed by repeating the method of Example 1 except for the above.

In this way, as shown in FIG. 2D, a buried-type variant in which the ratio of the core width w to the core height h is 1.00 and the etching depth is 110% of the core height. A polyimide optical waveguide was obtained. The guided light in the TE mode of the optical waveguide was a single mode. The loss in the TE mode and the TM mode of the optical waveguide is as follows.
Both are 1.0 dB / cm or less, and the polarization dependent loss is 0.1 dB / cm.
It was 5 dB / cm or less.

Example 7 A polyamic acid DMAc synthesized from 50 mol% of 6FDA, 10 mol% of ODA and 40 mol% of TFDB as a material for forming the core layer.
Using the solution, a core layer made of a polyimide copolymer of 20 mol% of 6FDA / ODA and 80 mol% of 6FDA / TFDB was formed, and the core height (core layer thickness) was set to 8.
An optical waveguide was formed by repeating the method of Example 1 except that the line width was set to 2 μm, the line width was set to 8.2 μm, and the etching depth was set to 6.5 μm.

In this manner, as shown in FIG. 2E, a buried-type variant in which the ratio of the core width w to the core height h is 1.00 and the etching depth is 79% of the core height. A polyimide optical waveguide was obtained. The guided light in the TE mode of the optical waveguide was a single mode. The loss in the TE mode and the TM mode of the optical waveguide is 1.0 dB / cm or less, and the polarization dependent loss is 0.5 dB / cm.
It was less than dB / cm.

Example 8 As a material for forming the lower cladding layer and the upper cladding layer, a DMAc solution of a polyamic acid synthesized from 50 mol% of 6FDA, 15 mol% of ODA and 35 mol% of TFDB was used. , 30 mol% 6FDA / ODA and 70 mol% 6FDA / TFD
A polyamic acid synthesized from 100 mol% of 6FDA, 50 mol% of ODA, and 50 mol% of TFDB as a material for forming an upper cladding layer and a lower cladding layer comprising a polyimide copolymer with B and a core layer DMA
c solution, 50 mol% of 6FDA / ODA and 50 mol%
A core layer made of a polyimide copolymer with 6% FDA / TFDB (mol%) was formed, the core height (core layer thickness) was 8.0 μm, the line width was 7.3 μm, and the etching depth was 8. An optical waveguide was formed by repeating the method of Example 1 except that the thickness was 5 μm.

In this way, as shown in FIG. 2 (f), a buried-type variant having a ratio of core width w to core height h of 0.91 and an etching depth of 106% of the core height is used. A polyimide optical waveguide was obtained. The guided light in the TE mode of the optical waveguide was a single mode. The loss in the TE mode and the TM mode of the optical waveguide is as follows.
Both are 1.0 dB / cm or less, and the polarization dependent loss is 0.1 dB / cm.
It was 5 dB / cm or less. According to this embodiment, an optical waveguide having a core width smaller than the core height, that is, an optical waveguide that is fine and high-density with respect to the substrate surface could be manufactured.

Example 9 As a material for forming the lower cladding layer and the upper cladding layer, a DMAc solution of a polyamic acid synthesized from 50 mol% of 6FDA, 5 mol% of ODA and 45 mol% of TFDB was used. , 10 mol%
6FDA / ODA and 90 mol% 6FDA / TFDB
And an upper clad layer and a lower clad layer made of a polyimide copolymer having a core height (core layer thickness) of 7.5 μm, a line width of 6.1 μm, and an etching depth of 7.5 μm. An optical waveguide was formed by repeating the method of Example 1 except for the above.

Thus, as shown in FIG. 2 (g), the ratio of the core width w to the core height h is 0.81, and the etching depth is the same as the core height. The wave path was obtained. The guided light in the TE mode of the optical waveguide was a single mode. The loss in the TE mode and the TM mode of this optical waveguide is 1.0 dB / cm or less, and the polarization dependent loss is 0.5 dB.
B / cm or less. According to this embodiment, an optical waveguide having a core width smaller than the core height, that is, an optical waveguide that is fine and high-density with respect to the substrate surface could be manufactured.

Example 10 As materials for forming the core layer, 50 mol% of 6FDA, 12.5 mol% of ODA and
25 mol% of 6FDA / OD using a DMAc solution of polyamic acid synthesized from 7.5 mol% of TFDB.
An upper clad layer and a lower clad layer made of a polyimide copolymer of A and 75 mol% of 6FDA / TFDB are formed, the core height (core layer thickness) is set to 8.1 μm, and the line width is set to 6.0 μm. An optical waveguide was formed by repeating the method of Example 1 except that the etching depth was changed to 7.3 μm.

In this way, as shown in FIG. 2 (h), a buried type variant having a ratio of the core width w to the core height h of 0.74 and an etching depth of 90% of the core height is used. A polyimide optical waveguide was obtained. The guided light in the TE mode of the optical waveguide was a single mode. The loss in the TE mode and the TM mode of the optical waveguide is 1.0 dB / cm or less, and the polarization dependent loss is 0.5 dB / cm.
It was less than dB / cm. According to this embodiment, an optical waveguide having a core width smaller than the core height, that is, an optical waveguide that is fine and high-density with respect to the substrate surface could be manufactured.

(Examples 11 to 20) Instead of aluminum used as an etching mask for a core layer and a positive photoresist used for forming a mask pattern, a silicon-based resist excellent in oxygen plasma properties was used as a mask layer. Example 1 was repeated except that the silicon-based resist was patterned.
1 to 20 optical waveguides were produced. The waveguide modes of the optical waveguides of Examples 11 to 20 were all single modes. Further, the loss in the TE mode and the TM mode of the optical waveguides of Examples 11 to 20 and the polarization dependent loss were all equal to those of the optical waveguides of Examples 1 to 10.

Comparative Example 1 The method of Example 1 was repeated except that the core height (core layer thickness) was 8.2 μm, the line width was 8.2 μm, and the etching depth was 8.2 μm. By repeating this, a buried-type irregularly shaped polyimide optical waveguide was formed in which the ratio of the core width w to the core height h was 1.00 and the etching depth was the same as the core height.

However, in this optical waveguide, the loss in the TE mode and the TM mode fluctuated due to the difference in the position of the light input / output end face, that is, the position of cutting out from the 4-inch wafer. Furthermore, as compared with Examples 1 to 5 and Example 7, the occurrence of processing defects due to the undulation of the core pattern was more frequent.

[0083]

As described above, the modified polyimide optical waveguide of the present invention not only reduces the loss in the TE mode and the TM mode, but also improves the pattern processing accuracy, as compared with the conventional polyimide optical waveguide. The mounting density in the substrate surface can be improved.

The modified polyimide optical waveguide of the present invention can be applied to various optical wirings (high-efficiency or low-density, straight or curved, high-efficiency connection with a light emitting surface and a light incident surface having various shapes). The present invention can also be applied to optical components including branch circuits or directional couplers. Further, the polyimide optical waveguide of the present invention has an effect of suppressing performance deterioration due to cracks or stress.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a method for manufacturing a modified polyimide optical waveguide of the present invention.

FIG. 2 is a schematic sectional view of a modified polyimide optical waveguide of the present invention.

Continuation of the front page (72) Inventor Shinji Ando 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Fumio Yamamoto 2-3-1 Otemachi, Chiyoda-ku, Tokyo Date (72) Inventor Noriyoshi Yamada 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term (reference) 2H047 KA04 PA24 PA28 QA05 TA35

Claims (18)

[Claims] 1. A lower cladding layer, a core on the lower cladding layer, and an upper cladding layer covering the lower cladding layer and the core, wherein the lower cladding layer, the core, and the upper cladding layer are made of polyimide. In a buried-type modified polyimide optical waveguide manufactured using a material, the core has a rectangular cross section in which a ratio of core width to core height is greater than 1 and 2 or less, and the core is formed. The thickness of the lower cladding layer where there is no
%, Wherein the thickness is less than the thickness of the lower cladding layer in the portion where the core is formed, within a range of greater than 30% and less than 30%. 2. A lower cladding layer, a core on the lower cladding layer, and an upper cladding layer covering the lower cladding layer and the core, wherein the lower cladding layer, the core, and the upper cladding layer are made of polyimide. In a buried-type modified polyimide optical waveguide manufactured using a material, the core has a rectangular cross section in which a ratio of core width to core height is greater than 1 and 2 or less, and the core is formed. A modified polyimide optical waveguide, characterized in that the thickness of the lower cladding layer in the portion where there is no core is equal to the thickness of the lower cladding layer in the portion where the core is formed. 3. A lower cladding layer, a core layer having a projection on the lower cladding layer, and an upper cladding layer covering the lower cladding layer and the core layer. Wherein the lower clad layer, the core layer, and the upper clad layer are made of a polyimide material, and wherein the core has a core width to a core height. Is greater than 1 and 2
The modified polyimide photoconductive member having a rectangular cross-section as follows, and a thickness of the core layer in a portion where the protrusion is not formed is greater than 0% and 30% or less of the core height. Wave path. 4. A lower cladding layer, a core on the lower cladding layer, and an upper cladding layer covering the lower cladding layer and the core, wherein the lower cladding layer, the core, and the upper cladding layer are made of polyimide. In a buried-type irregularly shaped polyimide optical waveguide manufactured using a material, the core has a square cross section in which a ratio of a core width to a core height is 1, and a lower clad in a portion where the core is not formed. The layer thickness is greater than 0% of the core height and 3
The modified polyimide optical waveguide, wherein the thickness is less than or equal to 0% and is smaller than the thickness of the lower clad layer in the portion where the core is formed. 5. A lower cladding layer, a core layer having a projection on the lower cladding layer, and an upper cladding layer covering the lower cladding layer and the core layer. Wherein the lower clad layer, the core layer, and the upper clad layer are made of a polyimide material, and wherein the core has a core width to a core height. And the thickness of the core layer in a portion where the protrusion is not formed is greater than 0% and 30% or less of the core height. Deformed polyimide optical waveguide. 6. A lower cladding layer, a core on the lower cladding layer, and an upper cladding layer covering the lower cladding layer and the core, wherein the lower cladding layer, the core, and the upper cladding layer are made of polyimide. In the buried type irregularly shaped polyimide optical waveguide manufactured using a material, the core has a rectangular cross section having a ratio of core width to core height of 0.7 or more and less than 1, and the core is formed. The thickness of the lower cladding layer in the portion where there is no core is less than the thickness of the lower cladding layer in the portion where the core is formed, within a range of more than 0% and not more than 30% of the height of the core.
A modified polyimide optical waveguide, characterized in that: 7. A lower cladding layer, a core on the lower cladding layer, and an upper cladding layer covering the lower cladding layer and the core, wherein the lower cladding layer, the core, and the upper cladding layer are made of polyimide. In the buried type irregularly shaped polyimide optical waveguide manufactured using a material, the core has a rectangular cross section having a ratio of core width to core height of 0.7 or more and less than 1, and the core is formed. A modified polyimide optical waveguide, characterized in that the thickness of the lower cladding layer in the portion where there is no core is equal to the thickness of the lower cladding layer in the portion where the core is formed. 8. A lower cladding layer, a core layer having a projection on the lower cladding layer, and an upper cladding layer covering the lower cladding layer and the core layer. Wherein the lower clad layer, the core layer, and the upper clad layer are made of a polyimide material, and wherein the core has a core width to a core height. Has a rectangular cross-section with a ratio of 0.7 to less than 1, and the thickness of the core layer in a portion where the protrusion is not formed is greater than 0% of the core height and 30% or less. A modified polyimide optical waveguide, characterized in that: 9. The polyimide material according to the formula (1)
A fluorine-containing polyimide comprising a repeating unit represented by any of (3), 2 selected from formulas (1) to (3)
The modified polyimide optical waveguide according to any one of claims 1 to 8, wherein the modified polyimide optical waveguide is selected from the group consisting of a fluorine-containing polyimide copolymer composed of a kind or three kinds of repeating units, and a mixture thereof. Embedded image Embedded image Embedded image 10. A step of laminating a lower clad layer and a core layer, and a step of forming a core by etching the core layer, wherein the core has a ratio of core width to core height of more than 1 and 2 The core layer has an etching depth greater than 100% of the core layer height and
A step of laminating an upper clad layer, wherein the lower clad layer, the core layer and the upper clad layer are produced using a polyimide material. Method. 11. A step of laminating a lower clad layer and a core layer, and a step of etching the core layer to form a core, wherein the core has a ratio of core width to core height of more than 1 and 2 A step of laminating an upper clad layer having a rectangular cross section that is equal to or less than an etching depth of the core layer and a step of laminating an upper clad layer; Is a method for manufacturing a modified polyimide optical waveguide, which is manufactured using a polyimide material. 12. A step of laminating a lower cladding layer and a core layer, and a step of etching the core layer to form a core, wherein the core has a ratio of core width to core height of more than 1 and 2 The lower cladding layer having a rectangular cross section that is equal to or less than 70% and less than 100% of the height of the core layer, and a step of laminating an upper cladding layer. A method for manufacturing a modified polyimide optical waveguide, wherein the layer, the core layer, and the upper clad layer are manufactured using a polyimide material. 13. A step of laminating a lower clad layer and a core layer, and a step of etching the core layer to form a core, wherein the core has a square cross section having a ratio of core width to core height of 1. And a step in which the etching depth of the core layer is greater than 100% and less than or equal to 130% of the height of the core layer; and a step of laminating an upper cladding layer. The method for manufacturing a modified polyimide optical waveguide, wherein the layer and the upper cladding layer are manufactured using a polyimide material. 14. A step of laminating a lower clad layer and a core layer, and a step of etching the core layer to form a core, wherein the core has a square cross section having a ratio of core width to core height of 1. And a step in which the etching depth of the core layer is 70% or more and less than 100% of the height of the core layer; and a step of laminating an upper cladding layer, wherein the lower cladding layer, the core layer and A method for manufacturing a modified polyimide optical waveguide, wherein the upper clad layer is manufactured using a polyimide material. 15. A step of laminating a lower clad layer and a core layer, and a step of forming a core by etching the core layer, wherein the core has a ratio of core width to core height of 0.7 or more and 1 or more. And the etching depth of the core layer is greater than 100% and 130% of the height of the core layer.
A method for producing an odd-shaped polyimide optical waveguide, comprising the following steps: and a step of laminating an upper clad layer, wherein the lower clad layer, the core layer, and the upper clad layer are produced using a polyimide material. 16. A step of laminating a lower cladding layer and a core layer, and a step of forming a core by etching the core layer, wherein the core has a ratio of core width to core height of 0.7 or more and 1 or more. A step of laminating an upper clad layer having a rectangular cross-section less than and having an etching depth of the core layer equal to the height of the core layer, wherein the lower clad layer, the core layer and the upper clad layer Is a method for manufacturing a modified polyimide optical waveguide, which is manufactured using a polyimide material. 17. A step of laminating a lower clad layer and a core layer, and a step of forming a core by etching the core layer, wherein the core has a ratio of core width to core height of 0.7 or more and 1 or more. A step of laminating an upper clad layer having a rectangular cross section of less than 70% and an etching depth of the core layer being 70% or more and less than 100% of the height of the core layer; A method for manufacturing a modified polyimide optical waveguide, wherein the layer, the core layer, and the upper clad layer are manufactured using a polyimide material. 18. The polyimide material according to the formula (1)
A fluorine-containing polyimide comprising a repeating unit represented by any of (3), 2 selected from formulas (1) to (3)
The method for producing a modified polyimide optical waveguide according to any one of claims 10 to 17, wherein the method is selected from the group consisting of a fluorine-containing polyimide copolymer composed of a kind or three kinds of repeating units, and a mixture thereof. . Embedded image Embedded image Embedded image