JP2003041003A - Polyimide and optical part by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyimide excellent in transparency, an isotropic property and crack resistance (without cracks on forming multilayers, easy for forming the multilayers and having a good processing property), and an optical part excellent in optical properties. SOLUTION: This polyimide having (a) <=0.02 difference between the refractive indexes of a TE mode and TM mode, (b) >=250 deg.C glass transition temperature (Tg) and (c) <=1 DB/cm light transmittance loss in 0.7-1.6 μm wave length, the polyimide having (b) >=250 deg.C glass transition temperature (Tg), (c) <=1 DB/cm light transmitiance loss in 0.7-1.6 μm wave length and (d) <=22.6 wt.% fluorine content, or the polyimide having (a) <=0.02 difference between the refractive indexes of the TE mode and TM mode, (b) >=250 deg.C glass transition temperature (Tg), (c) <=1 DB/cm light transmittance loss in 0.7-1.6 μm wave length and (d) <=22.6 wt.% fluorine content, and the optical part by using at least one of the polyimides are provided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyimide and an optical component using the same.

[0002]

2. Description of the Related Art Polyimide is used as an interlayer insulating film for electronic parts, a multilayer wiring board material, etc., due to its excellent heat resistance such that it can withstand a semiconductor process temperature. These polyimides are required to have a low dielectric constant from the viewpoint of speeding up signals. Further, polyimide is beginning to be expected as an electronic / optical component of optical communication and optical information processing systems, and an optical waveguide in an optical component, and the polyimide is required to have a small optical transmission loss, that is, transparency. Various polyimides having such a low dielectric constant and transparency have been recently developed, and for example, JP-A-4-239037, JP-A-4-328504, and JP-A-4-32.
An example is reported in Japanese Patent No. 8127. Also, Macromolecules, Volume 27, 6665
The page 6670 (1994) also details the optical transmission loss for these polyimides.

In these polyimides, fluorine atoms are substituted in order to improve the low dielectric constant and transparency. But,
When the number of fluorine substitutions increases and the fluorine content increases,
Cracks occur when forming a multilayer film, making it difficult to form multiple layers, poor processability, difficulty in synthesizing the polyimide precursor solution with high molecular weight, and difficult storage stability of the polyimide precursor solution. Since the viscosity is likely to change, problems such as deterioration occur.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art. An object of the present invention is to provide a polyimide having excellent transparency and isotropy. Another object of the present invention is to provide a polyimide having excellent transparency and crack resistance (a crack does not occur during formation of a multi-layer film, multi-layering is easy, and workability is good). Still another object of the present invention is to
An object of the present invention is to provide a polyimide having excellent transparency, isotropy and crack resistance. Still another object of the present invention is to provide a polyimide having excellent heat resistance, transparency and easiness of synthesis. Yet another object of the present invention is to provide an optical component having excellent optical characteristics.

[0005]

According to the present invention, (a) the refractive index difference between the TE mode and the TM mode is 0.02 or less,
(B) the glass transition temperature (Tg) is 250 ° C. or higher,
(C) The optical transmission loss at a wavelength of 0.7 to 1.6 μm is 1
It relates to a polyimide having a dB / cm or less (hereinafter referred to as a first invention). Moreover, this invention is (b) glass transition temperature (Tg) is 250 degreeC or more, and (c) wavelength 0.7-.
The optical transmission loss at 1.6 μm is 1 dB / cm or less,
(D) The present invention relates to a polyimide having a fluorine content of 22.6% by weight or less (hereinafter referred to as the second invention). Further, in the present invention, (a) the difference in refractive index between the TE mode and the TM mode is 0.
02 or less, (b) glass transition temperature (Tg) is 25
A polyimide having a temperature of 0 ° C or higher, (c) an optical transmission loss of 1 dB / cm or less at a wavelength of 0.7 to 1.6 µm, and (d) a fluorine content of 22.6% by weight or less (hereinafter, referred to as a third
Invention)).

The present invention also has a chemical structure represented by the general formula (I)

[Chemical 3] (In the formula, R ¹ represents a tetravalent aromatic group, and R ² is represented by the general formula (I
I) or general formula (III)

[Chemical 4] (However, X is a single bond, O, S, SO ₂ , CH ₂ , CO,
CONHC (CH ₃ ) ₂ or N (C ₆ H ₅ ) is shown, and Y ^{1 to} Y ¹²
Each independently represent H, CH ₃ , CN or NO ₂ )) and an optical component using the polyimide.

The range of the polyimide of the first invention and the range of the polyimide of the second invention are substantially overlapped with each other, but there is a part where they are not overlapped. The overlapping portion of the first invention and the second invention corresponds to the third invention.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyimide of the first invention is not particularly limited as long as it satisfies the above conditions (a), (b) and (c). The polyimide of the second invention is not particularly limited as long as it satisfies the above conditions (b), (c) and (d). The polyimide of the third invention is not particularly limited as long as it satisfies the above conditions (a), (b), (c) and (d).

The polyimide of the first, second or third invention can be produced by various conventional methods. For example, a polyimide obtained by reacting an acid component and a diamine component, an acid component and a diisocyanate component The polyimide and the like obtained by reacting Here, examples of the acid component include an acid anhydride, a half ester of an acid anhydride, and an acid chloride. When a polyimide is obtained by reacting an acid component and a diamine component, for example, by reacting an acid anhydride component and a diamine component, first, a polyamic acid as a polyimide precursor is obtained, and then this polyamic acid is dehydrated and ring-closed. Can be imidized to obtain a polyimide. Alternatively, the polyimide may be formed in one step without passing through the above two-step process.

The polyimide of the first or third invention is TE
It is necessary that the refractive index difference between the mode and the TM mode is 0.02 or less. When the difference in refractive index between the TE mode and the TM mode exceeds 0.02, the anisotropy is too large to be used for a device which is required to be isotropic. TE mode and T
The difference in refractive index in the M mode can be adjusted by selecting the type and amount of the acid component and diamine component used. TE
The refractive index of the mode and the TM mode can be measured by a commercially available device, and examples of such a device include a prism coupler model 2010 (manufactured by Metricon Corporation).

The polyimide of the second or third invention is required to have a fluorine content of 22.6% by weight or less, preferably 22.4% by weight or less.
It is more preferable to set it to 2% by weight or less. If the fluorine content exceeds 22.6% by weight, cracks may occur during the formation of a multilayer film, making it difficult to form a multilayer, poor processability, and difficulty in synthesizing a solution of a polyimide precursor into a high molecular weight. It becomes difficult, or the storage stability of the solution of the polyimide precursor is deteriorated because the viscosity tends to be lowered.
The fluorine content of the polyimide can be adjusted by selecting the types and amounts of the acid component and diamine component used.

The glass transition temperature (Tg) of the polyimide of the first, second or third invention needs to be 250 ° C. or higher, preferably 270 ° C. or higher. When the glass transition temperature (Tg) is less than 250 ° C., the heat resistance to a thermal process such as solder connection is poor, and it is difficult to apply it to optical parts. The glass transition temperature (Tg) can be easily measured by using a commercially available device.

The optical transmission loss of the polyimide of the first, second or third invention at 0.7 to 1.6 μm must be 1 dB / cm or less. When the optical transmission loss exceeds 1 dB / cm, it is difficult to apply to optical parts because of poor transparency. The optical transmission loss is defined as the amount by which the guided light in the polyimide film is attenuated by Rayleigh scattering or the like, and a method of measuring the optical transmission loss will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of an optical transmission loss measurement substrate on which a prism is mounted. In FIG. 1, silicon oxide 2 is formed on a silicon substrate 1, and a prism 4 is placed on a polyimide film 3 formed on the silicon oxide 2.
For example, 1.3 μm laser light is introduced into the polyimide film 3 as an incident light beam 5 through a prism. And
The optical transmission loss can be measured by a method of detecting the amount of attenuation of guided light guided in the film. Usually, the following three detection methods are often used.

The first method is a method using a CCD camera, which is the most inferior among the three in terms of sensitivity, but is a simple and effective method for material screening. The second is a method in which a detector such as a photodiode is swept directly on the guided light to measure scattered light. The third method is called the prism coupler method, which has the highest sensitivity and is a method of setting the second prism at the detection position and measuring the emitted light. The glass transition temperature and light transmission loss at 0.7 to 1.6 μm of polyimide do not depend on the fluorine content, but are related to the fluorine content by appropriately selecting the type and amount of the acid component and diamine component to be used. Can be easily adjusted without.

Among the polyimides of the first, second or third inventions, from the viewpoint of heat resistance, optical characteristics, easiness of synthesis, etc.
General formula (I) as a chemical structure

[Chemical 5] (In the formula, R ¹ represents a tetravalent aromatic group, and R ² is represented by the general formula (I
I) or general formula (III)

[Chemical 6] (However, X is a single bond, O, S, SO ₂ , CH ₂ , CO,
CONHC (CH ₃ ) ₂ or N (C ₆ H ₅ ) is shown, and Y ^{1 to} Y ¹²
Each independently represent H, CH ₃ , CN or NO ₂ )), and a polyimide containing a unit structure represented by the formula) The polyimide does not have to be, and may include any other unit structure as long as it includes the unit structure represented by the general formula (I). General formula (I)
The unit structure represented by is preferably contained in the polyimide in an amount of 50 mol% or more, more preferably 70 mol% or more.

Although the polyimide of the first, second or third invention is mainly passive,
This polyimide has 4-N, N-dimethylamino-4'-
Other materials, such as nitrostilbene, which have non-linearity are mixed by stimulation from the outside such as electricity, heat, light, etc., or a substituent having non-linearity is added to the polyimide to make the polyimide non-linear and It can also have active properties such as intensity modulation, phase modulation, wavelength conversion, etc.

The polyamic acid which is the precursor of the polyimide of the first, second or third invention is, for example, N-methyl-2.
-Pyrrolidone, N, N-dimethylacetamide, γ-butyrolactone, dimethylsulfoxide, diglyme and the like are obtained in a polar solution by the reaction of the acid anhydride component and the diamine component. It is preferable to react the acid anhydride component and the diamine component in substantially equimolar amounts, and the reaction temperature is usually
The reaction time is usually in the range of 30 minutes to 50 hours.

Examples of the acid anhydride component containing fluorine include (trifluoromethyl) pyromellitic dianhydride,
Di (trifluoromethyl) pyromellitic dianhydride, di (heptafluoropropyl) pyromellitic dianhydride,
Pentafluoroethyl pyromellitic dianhydride, bis {3,5-di (trifluoromethyl) phenoxy} pyromellitic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride Things, 5,
5'-bis (trifluoromethyl) -3,3 ', 4,4
′ -Tetracarboxybiphenyl dianhydride, 2,2 ′,
5,5'-tetrakis (trifluoromethyl) -3,3
′, 4,4′-tetracarboxybiphenyl dianhydride,
5,5'-bis (trifluoromethyl) -3,3 ',
4,4'-tetracarboxydiphenyl ether dianhydride, 5,5'-bis (trifluoromethyl) -3,3
′, 4,4′-Tetracarboxybenzophenone dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} benzene dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} trifluoromethylbenzene dianhydride, bis (Dicarboxyphenoxy) trifluoromethylbenzene dianhydride, bis (dicarboxyphenoxy) bis (trifluoromethyl) benzene dianhydride, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene dianhydride, 2,2 -Bis {(4- (3,4-dicarboxyphenoxy) phenyl} hexafluoropropane dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} biphenyl dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy } Bis (Trifluo And bis ((trifluoromethyl) dicarboxyphenoxy} diphenyl ether dianhydride, bis (dicarboxyphenoxy) bis (trifluoromethyl) biphenyl dianhydride and the like.

As the acid anhydride component containing no fluorine,
For example, para-terphenyl-3,4,3 ', 4'-tetracarboxylic dianhydride, pyromellitic dianhydride,
3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyl ether tetracarboxylic Acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,3,5,6-
Pyridine tetracarboxylic dianhydride, 1,4,5,8-
Naphthalenetetracarboxylic dianhydride, 3,4,9,1
0-perylenetetracarboxylic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, 3,3 ', 4,4'-tetraphenylsilanetetracarboxylic dianhydride, meta-
Terphenyl-3,3 ', 4,4'-tetracarboxylic dianhydride, 3,3', 4,4'-diphenyl ether tetracarboxylic dianhydride, 1,3-bis (3,4-dicarboxy) Phenyl) -1,1,3,3-tetramethyldisiloxane dianhydride, 1- (2,3-dicarboxyphenyl) -3- (3,4-dicarboxyphenyl) -1,
Examples include 1,3,3-tetramethyldisiloxane dianhydride.

Examples of the diamine component containing fluorine include 4- (1H, 1H, 11H-eicosafluoroundecanoxy) -1,3-diaminobenzene and 4- (1
H, 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,
(2,5) -diaminobenzotrifluoride, bis (trifluoromethyl) phenylenediamine, diaminotetra (trifluoromethyl) benzene, diamino (pentafluoroethyl) benzene, 2,5-diamino (perfluorohexyl) benzene, 2 , 5-diamino (perfluorobutyl) benzene, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 3,
3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, octafluorobenzidine, 4,4'-
Diaminodiphenyl ether, 2,2-bis (4-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- (4-amino-
2-trifluoromethylphenoxy) benzene, bis (aminophenoxy) bis (trifluoromethyl) benzene, bis (aminophenoxy) tetrakis (trifluoromethyl) benzene, 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) 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, bis {2-[(aminophenoxy ) Phenyl]
Hexafluoroisopropyl} benzene, 4,4′-bis (4-aminophenoxy) octafluorobiphenyl and the like can be mentioned.

As the diamine component containing no fluorine,
For example, 4,4'-diaminodiphenyl ether, 4,
4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, benzine, metaphenylenediamine, paraphenylenediamine, 2,2-bis- (4-aminophenoxyphenyl) propane, 1 , 5-naphthalenediamine, 2,6-naphthalenediamine, bis- (4-aminophenoxyphenyl) sulfone, bis- (4-aminophenoxyphenyl) sulfide, bis- (4-aminophenoxyphenyl) biphenyl, 1,4- Bis- (4-
Aminophenoxy) benzene, 1,3-bis- (4-aminophenoxy) benzene, 3,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4 , 4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether-3-sulfonamide, 3,4'-diaminodiphenyl ether-4-sulfonamide, 3,4'-diaminodiphenyl ether-3'-sulfonamide, 3,3 ´
-Diaminodiphenyl ether-4-sulfonamide,
4,4'-diaminodiphenylmethane-3-sulfonamide, 3,4'-diaminodiphenylmethane-4-sulfonamide, 3,4'-diaminodiphenylmethane-3
′ -Sulfonamide, 3,3′-diaminodiphenylmethane-4-sulfonamide, 4,4′-diaminodiphenylsulfone-3-sulfonamide, 3,4′-diaminodiphenylsulfone-4-sulfonamide, 3,4 ′
-Diaminodiphenylsulfone-3'-sulfonamide, 3,3'-diaminodiphenylsulfone-4-sulfonamide, 4,4'-diaminodiphenylsulfide-3-sulfonamide, 3,4'-diaminodiphenylsulfide-4- Sulfonamide, 3,3'-diaminodiphenyl sulfide-4-sulfonamide,
3,4'-diaminodiphenyl sulfide-3'-sulfonamide, 1,4-diaminobenzene-2-sulfonamide, 4,4'-diaminodiphenyl ether-3
-Carbonamide, 3,4'-diaminodiphenyl ether-4-carbonamide, 3,4'-diaminodiphenyl ether-3'-carbonamide, 3,3'-diaminodiphenyl ether-4-carbonamide, 4,4
′ -Diaminodiphenylmethane-3-carbonamide,
3,4'-diaminodiphenylmethane-4-carbonamide, 3,4'-diaminodiphenylmethane-3'-carbonamide, 3,3'-diaminodiphenylmethane-
4-carbonamide, 4,4'-diaminodiphenylsulfone-3-carbonamide, 3,4'-diaminodiphenylsulfone-4-carbonamide, 3,4'-diaminodiphenylsulfone-3'-carbonamide, 3,
3'-diaminodiphenyl sulfone-4-carbonamide, 4,4'-diaminodiphenyl sulfide-3-
Carbonamide, 3,4'-diaminodiphenylsulfide-4-carbonamide, 3,3'-diaminodiphenylsulfide-4-carbonamide, 3,4'-
Diaminodiphenyl sulfide-3'-sulfonamide, 1,4-diaminobenzene-2-carbonamide,
4,4'-bis (4-aminophenoxy) biphenyl,
Examples thereof include bis {4- (3-aminophenoxy) phenyl} sulfone. The above-mentioned acid anhydride component and diamine component may be used in combination of two or more kinds.

The polyimide of the first, second or third invention is, for example, spin coated with a solution of the above-mentioned polyimide precursor, polyamic acid, on an aluminum plate and stepped from 70 ° C. to 350 ° C. in a nitrogen atmosphere. It can be produced by heating (70 ° C. for 1 hour, 160 ° C. for 1 hour, 250 ° C. for 1 hour, 350 ° C. for 1 hour) and imidizing.

In the optical component using the polyimide of the first, second or third aspect of the invention, the polyimide is usually used in a portion that performs an optical operation or an optical function. Examples of such optical components include passive optical components and active optical components. Passive optical components include prisms, ridge elements, optical path conversion elements such as non-branching waveguides (including curved waveguides), branching waveguides, directional couplers, multiplexers / demultiplexers such as star couplers, and interference filters. , A polarizer, a wave plate (retarder), and the like. The optical components of the active system include optical matrix switches such as waveguide type optical switches such as Mach-Zehnder type optical switches and directional coupler type optical switches, waveguides such as Mach-Zehnder type optical modulators and directional coupling type optical modulators. Type optical modulator, optical polarizer, optical isolator, optical wavelength filter using asymmetric directional coupler, second harmonic generator (SH
G), an optical amplifier and the like.

The polyimide of the first, second or third invention is used in combination with a non-linear material as a material of an active optical component capable of responding to external stimuli such as heat, electricity and light. You can The non-linear material is not particularly limited, and known materials can be used. For example, the non-linear material having the following structure can be used.

[0025]

[Chemical 7]

The material used for the active optical component using the polyimide of the first, second or third invention is, for example,
It can be easily adjusted by adding the above-mentioned non-linear material to the solution of the polyamic acid which is the above-mentioned polyimide precursor and mixing them by stirring or the like. At this time, the amount of the non-linear material used is preferably in the range of 0.01 to 100 parts by weight with respect to 100 parts by weight of the polyimide precursor,
More preferably 0.1 to 50 parts by weight, 0.3
It is particularly preferable that the amount is ˜30 parts by weight. If the amount used is too small or too large, the non-linear characteristics, other optical characteristics, mechanical characteristics, stability, workability, etc. tend to be inferior.

As an example of the optical component using the polyimide of the present invention, an active optical component using a material in which polyimide and a nonlinear material are combined will be described below with reference to the drawings. FIG. 2 is a schematic sectional view showing a basic form of an optical matrix switch and an optical modulator. These optical matrix stitches and optical modulators are (a) linear type, (b) Y branch type, and as basic forms, (c) directional coupler type, (d) crossing (x) type, (e) branching. It can be classified into an interference type and a (f) balance bridge type. For example, (a) In the linear type, light propagates through the core,
By applying a voltage at the electrodes, the index of refraction of the core can be changed to provide a desired optical actuation. In forming the optical waveguide, a general film forming method, for example, a spin coating method, an immersion method, a doctor blade method, a wire bar method, a roller method, a spray method or the like can be used. The core material and clad material of the optical waveguide are the wavelength of light,
It may be selected so that a difference in refractive index suitable for the intended use is obtained.

The optical waveguide in the active system described above is prepared by spin-coating a solution of a polyamic acid, which is a polyimide precursor, and a material containing a non-linear material on, for example, a silicon substrate and heat-treating it in a nitrogen atmosphere. An imide ring closure is performed to form a polyimide, and a non-linear material is also oriented to form an optical waveguide capable of switching and modulation. For example, manufacturing of a directional coupler type optical switch which is one mode of such an optical waveguide will be described with reference to FIG. FIG. 3 is a cross-sectional view for explaining the active optical waveguide manufacturing process. In FIG. 3, 6 is a substrate, 7 is a lower electrode, 8 is a lower cladding layer, 9 is a core layer, 10 is an aluminum layer, 11 is a resist layer, 12 is an upper cladding layer, and 13 is an upper electrode.

A lower electrode 7 made of aluminum or the like is formed on a substrate 6 made of silicon or the like by a vapor deposition method, a sputtering method or the like, and is then made of polyimide having a refractive index smaller than that of the core layer 9 made of the active material. The lower clad layer 8 is formed. The active material is applied thereon to a predetermined thickness and heated and cured to obtain the core layer 9. Next, after applying the aluminum layer 10 by a vapor deposition method or the like,
Resist coating, pre-baking, exposure, development and after-baking are performed to obtain a patterned resist layer 11.
After aluminum which is not protected by the resist layer 11 is removed by wet etching, the polyimide layer of the core layer 9 which is not protected by the aluminum layer 10 is removed by dry etching.

After peeling off the resist layer 11, the remaining aluminum layer 11 is removed by wet etching, and the upper clad layer 12 is formed thereon by using the polyimide used for forming the lower clad layer 8. Finally, the upper electrode 13 is formed on the predetermined core layer 9 through a mask pattern by a vapor deposition method, a sputtering method, or the like to obtain a directional coupler type optical switch.

In order to orient the nonlinear material contained in the core layer in the optical waveguide in the active system, poling treatment or the like may be performed. For example, the nonlinear material can be oriented at the same time while heating while applying an electric field to perform imidation by imide ring closure. Examples of the method of applying the electric field include a method of providing an electrode and a method of charging the surface by corona discharge. The strength of the electric field is preferably 10 ⁵ V / m or more, more preferably 10 ⁶ V / m or more. Further, after imidization by imide ring closure to obtain a final structure of polyimide, an electric field may be applied to the polyimide to heat it to a temperature of Tg or higher to orient the non-linear material. The waveguide is usually 5 to 15 μm wide,
It is formed with a height of 1 to 4 μm, and the pattern interval is 2 to 3
It is about μm.

[0032]

EXAMPLES The present invention will now be described in more detail with reference to examples. Example 1 Using a 1 liter glass four-necked flask, 30 ml
Paraphenylenediamine 29.36 g (0.27 mol), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride 120.64 g (0. 27 mol), N, N
850 g of dimethylacetamide were added. This solution was stirred at room temperature for 5 hours to obtain a polyimide precursor solution having a viscosity of 50 poise. This solution was spin-coated on a silicon wafer having a diameter of 5 inches and having a silicon oxide layer on the surface, and under a nitrogen atmosphere at 70 ° C. for 1 hour, 160 ° C. for 1 hour, 250 ° C. for 1 hour, and 350 ° C. for 1 hour. Heat
A polyimide film having a film thickness of 3 μm was obtained. The fluorine content of this polyimide film is shown in Table 3.

The glass transition temperature (Tg) of the obtained polyimide film, the presence or absence of cracks during the formation of the multilayer film, the refractive index and the optical transmission loss were measured by the following methods, and the results are shown in Tables 3 and 5. It was Glass transition temperature (Tg): After peeling the film from the silicon substrate, it was measured with a thermophysical property measuring device manufactured by Perkin Elmer. Presence or absence of cracks during multilayer film formation: Presence or absence of cracks during multilayer film formation by spin coating a polyimide precursor solution on a polyimide film-formed silicon wafer and forming a polyimide film in the same manner. I checked. Refractive index: Measured using a prism coupler model 2010 (manufactured by Metricon). Optical transmission loss: Using the apparatus of FIG. 1 described above, the prism coupler method was used as the detection method, and measurement was performed through light having a wavelength of 1.3 μm.

Examples 2 to 17 The acid anhydride component and the amine component in Example 1 were changed to those shown in Tables 1 and 2, and a polyimide precursor solution was synthesized with equimolar amounts. A polyimide film was obtained in the same manner as in Example 1. The fluorine content of this polyimide film is shown in Tables 3 and 4. Further, in the same manner as in Example 1, the glass transition temperature (Tg) of the obtained polyimide film, the presence or absence of cracks at the time of forming a multilayer film, the refractive index and the optical transmission loss were measured, and the results are shown in Table 3 and Table. 4, shown in Table 5 and Table 6.

[0035]

[Table 1]

[0036]

[Table 2]

The acid anhydride component and amine component shown in Tables 1 and 2 are as follows. 6FDA: 2,2-bis (3,4) dicarboxyphenylhexafluoropropane dianhydride PMDA: pyromellitic dianhydride S-BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride ODPA: 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride PPD: paraphenylenediamine AF-A: 2,2-bis {4- (4-aminophenoxy) phenyl} hexafluoropropane DDE: 4,4'-diaminodiphenyl ether DDS: 4,4'-diaminodiphenylsulfite MPD: metaphenylenediamine A-AF: 2,2'-bis (4-aminophenyl) hexafluoropropane 8FBPDA: 4,4'-bis (4-Aminophenoxy) octafluorobiphenyl 3,3′-DSF: 3,3′-diaminodi Enirusurufon DSF: 4,4'-diaminodiphenyl sulfone BAPP: 2,2'-bis (4-aminophenoxy) propane BAPB: 4,4'-bis (4-aminophenoxy) biphenyl

[0038]

[Table 3]

[0039]

[Table 4]

[0040]

[Table 5]

[0041]

[Table 6]

Comparative Examples 1 to 4 Table 7 shows the acid anhydride component and the diamine component in Example 1.
A polyimide film was obtained in the same manner as in Example 1 except that the polyimide film was changed to that shown in. The fluorine content of this polyimide film is shown in Table 8. Further, in the same manner as in Example 1, the glass transition temperature (Tg) of the obtained polyimide film, the presence or absence of cracks during the formation of a multilayer film, the refractive index and the optical transmission loss were measured, and the results are shown in Table 8 and Table. 9 shows.

[0043]

[Table 7]

The acid anhydride component and amine component shown in Table 7 are as follows. TPDA: para-terphenyl-3,4,3 ', 4'-
Tetracarboxylic acid dianhydride TFDB: 2,2'-bis (trifluoromethyl)-
4,4'-diaminobiphenyl mAPPS: bis {4- (3-aminophenoxy) phenyl} sulfone

[0045]

[Table 8]

[0046]

[Table 9]

Example 18 A method of manufacturing a passive optical waveguide which is one of optical components is shown in FIG. A 5-inch silicon wafer is used for the silicon wafer substrate 14, and a lower clad 15 is formed on the silicon wafer substrate 14.
Using N, N-dimethylacetamide (DMAC) as a solvent, pyromellitic dianhydride (PMDA) and 4,4 ′
A spin coat of a polyamic acid solution consisting of diaminodiphenyl ether (DDE) with a resin content of 15% by weight and a viscosity of 50 dPa · s, and heated in a dryer at 100 ° C. for 30 minutes,
Then, the film was heated at 200 ° C. for 30 minutes and then at 350 ° C. for 60 minutes to be cured to form a polyimide film having a film thickness of 10 μm. The refractive index of this film at a wavelength of 1300 nm is
It was 1.677. As the core layer 16 on this film,
Using DMAC as a solvent, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 1,4-
Resin content concentration 1 consisting of phenylenediamine (PPD)
A polyamide acid solution of 5 wt% and a viscosity of 50 dPa · s was spin-coated and cured under the same conditions to form a polyamide film having a thickness of 15 μm. The refractive index of this film was 1.781.

Next, as a resist, RU-1600P is used.
(Manufactured by Hitachi Chemical Co., Ltd.), spin coating, 1
After drying at 00 ° C., exposure and development are performed with a mercury lamp, reactive ion etching (O 2 -RIE) is performed with oxygen using this resist pattern 17 as a mask, and etching is performed so as to leave a predetermined pattern of the optical waveguide. Done,
After removing the resist, the upper clad 18
A polyamic acid composed of PMDA and DDE was spin-coated and cured so that the film thickness after curing would be 20 μm to form a linear optical waveguide having a length of 15 μm × width of 15 μm × length of 10 cm.

In order to investigate the light loss of this optical waveguide,
Both ends of the silicon wafer were cut by a dicing machine to prepare a sample. The method of measuring the optical loss is shown in FIG. The optical fiber 19 made of quartz is aligned with the end face of the cut optical waveguide so that the light having a wavelength of 1300 nm is incident, and the light transmitted through the optical waveguide and emitted from the opposite end face is detected by the optical sensor 20. To do. When the sample lengths of 5 cm and 10 cm were produced and the loss of the optical waveguide was determined from the slope of the attenuation of light, the optical loss was 0.6 dB / cm.

Example 19 In the same manner as in Example 1, a lower clad and an upper clad were formed, and P
Polyimide consisting of MDA and PPD is used as the core layer B
PDA and 1,4-diaminodiphenyl sulfide (DD
When the optical loss was measured using the polyimide of S), the optical loss was 0.8 dB / cm. BPDA and DD
The polyimide made of S had a refractive index of 1.694 at a wavelength of 1300 nm.

Comparative Example 5 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanoic acid dianhydride, which is a tetracarboxylic dianhydride containing fluorine, is used as the lower and upper clads in the same manner as in Example 1. (6FDA) and 2,2'-bis (4-aminophenyl) hexafluoropropane (6FDAM)
Polyimide is used, and BPDA and 6 are used for the core layer.
When an optical waveguide was manufactured using polyimide made of FDAM, cracks were found in the optical waveguide portion.

Comparative Example 6 In the same manner as in Example 1, a lower layer and an upper layer clad were formed, and P
A polyimide composed of MDA and DDE is used, and a polyimide composed of BPDA and 1,4-bis (4-aminophenoxy) benzene (TPE) is used for the core layer.
When an optical waveguide was prepared and the optical loss was measured, it was 1.8 dB.
It was / cm. This optical loss has a large value and is difficult to use as an optical waveguide. The refractive index of the film of this core layer was 1.694.

[0053]

The polyimide of the present invention is excellent in transparency, isotropic property, crack resistance, heat resistance and easiness of synthesis. The optical component of the present invention has excellent optical characteristics.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an optical transmission loss measurement substrate on which a prism is mounted.

FIG. 2 is a schematic sectional view showing a basic form of an optical matrix switch and a modulator.

FIG. 3 is a cross-sectional view illustrating an active optical waveguide manufacturing process.

FIG. 4 is a schematic diagram showing a method of manufacturing an optical waveguide. Here, (a) substrate, (b) formation of lower clad and core layer, (c) formation of resist pattern, (d) formation of core pattern by RIE, (e) resist removal, and (f)
The formation of the upper clad is shown.

FIG. 5 is a schematic view of an optical loss measuring device for an optical waveguide.

[Explanation of symbols]

1 Silicon substrate 2 Silicon oxide 3 Polyimide film 4 prism 5 incident rays 6 substrate 7 Lower electrode 8 Lower clad layer 9 core layer 10 Aluminum layer 11 Resist layer 12 Upper clad layer 13 Upper electrode 14 Silicon wafer substrate 15 Lower clad layer 16 core layer 17 Resist pattern 18 Upper clad layer 19 optical fiber 20 optical sensor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeo Nara             Hitachi, 4-13-1, Higashimachi, Hitachi, Ibaraki             Seikou Co., Ltd. Yamazaki Factory (72) Inventor Sato Court             Hitachi, 4-13-1, Higashimachi, Hitachi, Ibaraki             Seikou Co., Ltd. Yamazaki Factory (72) Inventor Shigeru Hayashida             Hitachi, 4-13-1, Higashimachi, Hitachi, Ibaraki             Seibari Co., Ltd. Ibaraki Research Institute (72) Inventor Masato Taya             Hitachi, 4-13-1, Higashimachi, Hitachi, Ibaraki             Seibari Co., Ltd. Ibaraki Research Institute F-term (reference) 2H047 PA02 PA21 PA24 PA28 QA05                 4J043 PA04 QB31 RA35 SA06 SA54                       SA55 SA56 SB02 TA21 TA22                       TA47 TA48 TA49 TB02 UA121                       UA122 UA131 UA132 UA141                       UA142 UB061 UB122 UB151                       UB152 UB301 XA16 YA06                       ZA51 ZB21

Claims (3)

[Claims] 1. A refractive index difference between TE mode and TM mode is 0.02 or less, and (b) a glass transition temperature (T).
g) is 250 ° C. or higher, and (c) wavelength is 0.7 to 1.6.
The optical transmission loss at μm is 1 dB / cm or less, (d)
A polyimide having a fluorine content of 22.6% by weight or less. 2. A chemical structure represented by the general formula (I): (In the formula, R ¹ represents a tetravalent aromatic group, and R ² is represented by the general formula (I
I) or general formula (III) (However, X is a single bond, O, S, SO ₂ , CH ₂ , CO,
CONHC (CH ₃ ) ₂ or N (C ₆ H ₅ ) is shown, and Y ^{1 to} Y ¹²
Each independently represent H, CH ₃ , CN or NO ₂ ).) The polyimide according to claim 1. 3. An optical component using the polyimide according to claim 1 or 2.