JP7280462B2 - Optical waveguide manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing an optical waveguide used for optical elements such as optical communication, optical wiring, or optical storage.

With the spread of optical communication and optical storage, the demand for optical elements that constitute them is increasing. Especially in optical communication, along with the practical use of optical wavelength division multiplexing transmission, the use of so-called backbone systems centering on optical fibers to metro and access systems is accelerating. For this reason, the use of optical elements used for adding/dropping optical signals, etc., is progressing from a combination of bulk materials to a planar waveguide that uses thin-film optical materials and is compact and easy to integrate.

A planar waveguide is usually formed of an amorphous material centering on silicon oxide on a quartz substrate or a silicon substrate. As a method for forming a thin film, a method of melting and forming a laminated material by a flame deposition method or a vapor phase epitaxy method such as a chemical vapor deposition method (CVD method) is used. The formed thin film is processed into a predetermined size and shape by a reactive ion etching method or the like, if desired, to form an optical element.

In Patent Document 1, an optical waveguide material layer formed on a quartz substrate by a sol-gel method is locally heat-treated according to a desired waveguide pattern, thereby partially forming the optical waveguide material layer. It is described that an optical waveguide is formed by heating and sintering to vitrify. However, the method described in Patent Document 1 is not industrially useful because the sintering step takes a long time and requires complicated steps such as local heating. In addition, shrinkage-relieving agents, thickeners, catalysts, and the like contained in the material of the optical waveguide material layer adversely affect the characteristics of the optical waveguide obtained, and the transparency and the like are not sufficiently satisfactory.

Further, in Patent Document 2, a core layer and a clad layer made of Pb _1-x La _x (Zr _y Ti _1-y ) _1-x/4 O ₃ (PLZT) are formed using an aerosol deposition method. to form a waveguide. However, the waveguide obtained by the manufacturing method described in Patent Document 2 was not sufficiently satisfactory in terms of optical characteristics such as transmittance. In addition, the obtained core layer and clad layer had a problem in film uniformity due to the presence of pores and heterogeneous phases. In addition, the aerosol deposition method described in Patent Document 2 requires a vacuum apparatus and further requires a step of flattening the surface of the film to be obtained.

In Patent Document 3, after forming Pb(Zr _0.3 Ti _0.7 )O ₃ by an aerosol deposition method, the light absorption edge is changed by local heating to form an optical waveguide including a core portion and a clad portion. It is described to make a However, the core part or the clad part formed by the aerosol deposition method has a problem that stable characteristics cannot be obtained due to the fact that fine particles having different refractive indices are contained therein. In addition, a complicated process such as local heating is required, and the local heating adversely affects the interface between the core and the clad, resulting in an increase in transmission loss due to scattering.

Therefore, there is a need for an industrially advantageous method for producing an optical waveguide having excellent optical properties such as transparency without the above problems.

JP-A-8-292335 JP 2005-181995 A JP 2007-298895 A

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel manufacturing method capable of simply and easily obtaining an optical waveguide having excellent optical properties such as transparency in a small number of steps.

As a result of intensive studies to achieve the above object, the present inventors have found that, in a method for manufacturing a waveguide by forming at least a core layer and a clad layer, the formation of the core layer and the clad layer is performed by forming a precursor of the core layer. When the raw material solution containing the body and the raw material solution containing the precursor of the cladding layer are each atomized or dropletized, and the obtained mists or droplets are thermally reacted on the substrate, optical properties such as transparency can be improved. We have found that an optical waveguide with excellent characteristics can be easily and simply manufactured in a small number of steps without the need for local heating or sintering. I found something.
Moreover, after obtaining the above knowledge, the inventors of the present invention conducted further studies and completed the present invention.

Specifically, the present invention relates to the following inventions.
[1] A method of manufacturing an optical waveguide by forming at least a core layer and a clad layer, wherein the formation of the core layer and the clad layer comprises a raw material solution containing a core layer precursor and a clad layer precursor. A method of manufacturing an optical waveguide, characterized by atomizing or dropletizing each of the raw material solutions containing the above-described method, and subjecting the obtained mists or droplets to a thermal reaction on a substrate.
[2] The manufacturing method according to [1], wherein the precursor of the core layer contains a first metal.
[3] The production method according to [2] above, wherein the first metal is a Group 14 metal of the periodic table.
[4] The manufacturing method according to any one of [1] to [3], wherein the precursor of the clad layer contains a second metal.
[5] The production method according to [4] above, wherein the second metal is a Group 14 metal of the periodic table.
[6] The production method according to any one of [1] to [5], wherein the atomization or dropletization is performed using ultrasonic vibration.
[7] after the atomization or dropletization, supplying a carrier gas to each of the mists or droplets obtained, conveying the mist or the droplets to the substrate with the carrier gas; The production method according to any one of [1] to [6], wherein the thermal reaction is performed.
[8] The production method according to any one of [1] to [7], wherein the thermal reaction is performed in a non-oxygen atmosphere.
[9] The production method according to any one of the above [1] to [8], wherein the thermal reaction is performed at a temperature of 150°C or less.

According to the film forming method according to the embodiment of the present invention, an optical waveguide having excellent optical properties such as transparency can be simply and easily manufactured in a small number of steps.

1 is a schematic configuration diagram of a film forming apparatus used in Examples. FIG. 1 is a schematic cross-sectional view showing a slab-type optical waveguide according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view showing an embedded optical waveguide according to an embodiment of the present invention; FIG.

A film forming method according to an embodiment of the present invention is a method of forming at least a core layer and a clad layer to manufacture a waveguide, wherein the formation of the core layer and the clad layer includes a precursor of the core layer. The raw material solution and the raw material solution containing the precursor of the cladding layer are each atomized or dropletized (atomization/droplet formation process), and the obtained mists or droplets are thermally reacted on the substrate (film formation process ).

(Atomization/dropletization process)
In the atomization/droplet formation step, the raw material solution containing the core layer precursor and the raw material solution containing the clad layer precursor are each atomized or dropletized to generate mist or droplets. The atomization/droplet formation means atomizes or forms droplets of a raw material solution containing a core layer precursor (core layer raw material solution) and a raw material solution containing a clad layer precursor (cladding layer raw material solution), respectively. There is no particular limitation as long as it is possible, and known atomization means may be used, but in the embodiment of the present invention, atomization/droplet formation means using ultrasonic waves is preferred. The mist preferably has an initial velocity of zero and floats in the air. For example, it is more preferable that the mist floats in space and can be transported as a gas, rather than being sprayed like a spray. The droplet size of the mist is not particularly limited, and may be about several millimeters, preferably 50 μm or less, more preferably 1 to 10 μm.

(raw material solution for core layer)
The raw material solution for the core layer is not particularly limited as long as it contains at least a core layer precursor and can be atomized or dropletized, and may contain an inorganic material or an organic material. You can Moreover, the raw material solution may contain both inorganic materials and organic materials.

(precursor of core layer)
The precursor of the core layer is not particularly limited as long as it does not interfere with the object of the present invention, and may be an inorganic material or an organic material. In an embodiment of the present invention, the precursor of the core layer preferably contains a metal (hereinafter also referred to as first metal). The first metal may be a metal element or a metal compound, but is preferably a metal compound in the embodiment of the present invention. Suitable examples of the first metal include Group 14 metals of the periodic table and metal compounds thereof. Examples of Group 14 metals of the periodic table include silicon (Si), germanium (Ge), tin (Sn), lead (Pb), etc. In an embodiment of the present invention, the first metal is Silicon (Si) is preferable, and a silicon-containing compound is more preferable, because it can form an optical waveguide of better quality.

The silicon-containing compound is not particularly limited as long as it is a compound containing at least one silicon. Examples of the silicon-containing compound include silane, siloxane, silazane, and polysilazane. Examples of the silane include monosilane (SiH ₄ ) and alkoxysilane. Examples of the alkoxysilane include tetraethoxysilane (TEOS), tetramethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraamyloxysilane, tetraoctyloxysilane, tetranonyloxysilane, dimethoxydiethoxysilane, dimethoxydiiso propoxysilane, diethoxydiisopropoxysilane, diethoxydibutoxysilane, diethoxyditrityloxysilane, or mixtures thereof. Examples of the siloxane include hexamethyldisiloxane, 1,3-dibutyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, 1,3-divinyltetramethyldisiloxane, hexaethyldisiloxane and 3-glycide. xypropylpentamethyldisiloxane and the like. Silazanes include, for example, hexamethyldisilazane and hexaethyldisilazane.

In an embodiment of the present invention, the silicon-containing compound is preferably polysilazane. The polysilazane is preferably polysilazane having a repeating unit represented by the following formula (1), more preferably polysilazane having a repeating unit represented by the following formula (2). In the following formula (1) or (2), the average repetition number is not particularly limited as long as it is an integer, but is preferably 2 to 1000, more preferably 2 to 100, and 2 to 10. Most preferably.

（式中、Ｒ^１、Ｒ^２およびＲ^３は、それぞれ同一または異なって、水素原子、ハロゲン原子、置換基を有していてもよい炭化水素基または置換基を有していてもよい複素環基を表し、Ｒ^１、Ｒ^２およびＲ^３から選ばれる任意の２つの基が結合して環を形成してもよい。）

(wherein R ¹ , R ² and R ³ are each the same or different and are a hydrogen atom, a halogen atom, an optionally substituted hydrocarbon group or an optionally substituted heterocyclic ring represents a group, and any two groups selected from R ¹ , R ² and R ³ may combine to form a ring.)

（式中、ｎは、平均繰り返し数であって、整数である。）

(Wherein n is the average number of repetitions and is an integer.)

The amount of the core layer precursor to be used is not particularly limited, but it is preferably an amount that completely dissolves in the solvent. For example, the precursor of the core layer is preferably dissolved in a raw material solution containing a solvent to a concentration of about 0.01 to 50% by volume, preferably 0.1 to 30% by volume. More preferably, it is dissolved, most preferably to a concentration of about 1-10% by volume.

(raw material solution for clad layer)
The raw material solution of the clad layer contains at least the precursor of the clad layer, is not particularly limited as long as it can be atomized or dropletized, and may contain an inorganic material or an organic material. You can Moreover, the raw material solution may contain both inorganic materials and organic materials.

(Precursor of clad layer)
The precursor of the clad layer is not particularly limited as long as it does not interfere with the object of the present invention, and may be an inorganic material or an organic material. In an embodiment of the present invention, the precursor of the core layer preferably contains a metal (hereinafter also referred to as a second metal). The second metal may be a metal element or a metal compound, but is preferably a metal compound in the embodiment of the present invention. Suitable examples of the second metal include Group 14 metals of the periodic table and metal compounds thereof. Examples of Group 14 metals of the periodic table include silicon (Si), germanium (Ge), tin (Sn) and lead (Pb). Silicon (Si) is preferable, and a silicon-containing compound is more preferable, because it can form an optical waveguide of better quality. Examples of the silicon-containing compound include the compounds exemplified as the silicon-containing compound. In an embodiment of the present invention, when the second metal is the same metal as the first metal, the interface between the core layer and the clad layer is improved, and an optical waveguide with excellent transparency is obtained. Therefore, it is preferable that the precursor of the clad layer is the same as the precursor of the core layer.

The amount of the clad layer precursor used is not particularly limited, but it is preferably an amount that completely dissolves in the solvent. For example, it is preferable to dissolve the precursor of the cladding layer in a raw material solution containing a solvent to a concentration of about 0.01 to 50% by volume, and a concentration of 0.1 to 30% by volume. More preferably, it is dissolved, most preferably to a concentration of about 1-10% by volume.

In an embodiment of the present invention, it is preferable that the raw material solution for the core layer and the raw material solution for the clad layer (hereinafter also simply referred to as "the raw material solution") contain an oxidizing agent. The oxidizing agent is not particularly limited as long as it does not interfere with the object of the present invention, and may be a known oxidizing agent. Examples of the oxidizing agent include aqueous hydrogen peroxide, nitric acid, ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, potassium peroxodisulfate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, periodine. One or more selected from acids, sodium periodate, potassium periodate, methanesulfonic acid, sulfuric acid and ethylenediamine sulfate. In an embodiment of the present invention, the oxidizing agent is preferably hydrogen peroxide water.

Although the amount of the oxidizing agent used is not particularly limited, it is preferably an amount that completely dissolves in the solvent. For example, the oxidizing agent is preferably dissolved in a raw material solution containing a solvent to a concentration of about 0.1 to 70%, more preferably about 1 to 50%. , is most preferably dissolved to a concentration of about 10-50%.

In the embodiment of the present invention, as the raw material solution, a solution obtained by dissolving or dispersing the precursor of the core layer or the precursor of the clad layer and optionally an oxidizing agent in a solvent can be preferably used. can. Examples of the solvent include organic solvents and inorganic solvents such as water. Examples of the organic solvent include ester solvents (eg, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, butyl propionate, etc.), ether solvents (eg, diethyl ether, tert-butyl methyl ether, Diglyme (e.g. diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, diethylene glycol diethyl ether), 1,2-dimethoxyethane, tetrahydrofuran, etc.), amide solvents (e.g. N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone) , 1,3-dimethyl-2-imidazolidinone, etc.), ketone solvents (e.g., methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, cyclopentanone, etc.), nitrile solvents (e.g., acetonitrile, propionitrile, etc.), alcohol solvents ( (e.g., methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, etc.), halogenated solvents (e.g., methylene chloride, chloroform, etc.), aromatic solvents (e.g., toluene, xylene, chlorobenzene, nitrobenzene). etc.), preferably an ester solvent. The raw material solution may contain various known additives and the like as long as they do not interfere with the object of the present invention. Water may be added.

(Film formation process)
In the film forming step, the respective mists or droplets obtained in the atomization/droplet forming step are thermally reacted on the substrate to form a film on the substrate. The thermal reaction is not particularly limited as long as the mist or liquid droplets react with heat, and the reaction conditions and the like are not particularly limited as long as the object of the present invention is not hindered. In this step, the thermal reaction is usually carried out at 300° C. or lower, preferably 150° C. or lower, more preferably 100° C. or lower. In addition, the thermal reaction may be carried out under vacuum, under a non-oxygen atmosphere, under a reducing gas atmosphere, or under an oxygen atmosphere as long as the object of the present invention is not hindered. It is preferably carried out in an atmosphere, more preferably in a non-oxygen atmosphere. The reaction may be carried out under atmospheric pressure, increased pressure or reduced pressure, but is preferably carried out under atmospheric pressure in the embodiment of the present invention. Note that the film thickness can be set by adjusting the film formation time.

In an embodiment of the present invention, after said atomization or dropletization, a carrier gas is supplied to each of the mists or droplets obtained, and said mist or said droplets are separated from said substrate by said carrier gas. Then, the thermal reaction is completely different from the case of spraying, etc., and the adhesion of the interface between the core layer and the clad layer to be formed can be further improved, and the obtained This is preferable because it is possible to better suppress surface unevenness of the optical waveguide. The carrier gas is not particularly limited as long as it does not interfere with the object of the present invention. Suitable examples include oxygen, ozone, inert gases such as nitrogen and argon, and reducing gases such as hydrogen gas and forming gas. mentioned. In addition, although one type of carrier gas may be used, two or more types may be used, and a diluted gas with a reduced flow rate (for example, a 10-fold diluted gas, etc.) may be further used as a second carrier gas. good too. In addition, the carrier gas may be supplied at two or more locations instead of at one location. Although the flow rate of the carrier gas is not particularly limited, it is preferably 0.01 to 20 L/min, more preferably 1 to 10 L/min. In the case of a diluent gas, the flow rate of the diluent gas is preferably 0.001 to 2 L/min, more preferably 0.1 to 1 L/min.

Further, in the embodiment of the present invention, it is preferable that the precursor of the core layer or the precursor of the clad layer and the oxidizing agent are separate raw material solutions. For example, the precursor of the core layer or the precursor of the clad layer is mixed with the solvent to form a first raw material solution, and the oxidizing agent is mixed with the solvent to form a second raw material solution. be done. In this case, the mist of the first raw material solution and the mist of the second raw material solution may be mixed before supplying the carrier gas to the mist after the atomization or dropletization, or the mist of the second raw material solution may be mixed with the carrier gas. They may be mixed during transportation, or may be mixed and formed on the substrate after transportation with a carrier gas. In the present invention, the mist of the first raw material solution and the mist of the second raw material solution are preferably mixed during transportation by the carrier gas.

(substrate)
The substrate is not particularly limited as long as it can support the core layer and the clad layer. The material of the substrate is also not particularly limited as long as it does not interfere with the object of the present invention, and may be a known substrate, an organic compound, or an inorganic compound. It may be a porous structure. The shape of the substrate may be any shape, and is effective for all shapes. Cylindrical, helical, spherical, ring-shaped, etc. are mentioned, but in the embodiment of the present invention, the substrate is preferable. The thickness of the substrate is not particularly limited in the embodiments of the present invention, but is preferably 10 μm to 100 mm, more preferably 100 μm to 10 mm.

The substrate is not particularly limited as long as it has a plate shape and serves as a support for the silicon oxide film. It may be an insulator substrate, a semiconductor substrate, a metal substrate, or a conductive substrate. In addition, a substrate having at least one film selected from a metal film, a semiconductor film, a conductive film and an insulating film formed on part or all of these surfaces can also be suitably used as the substrate. . In an embodiment of the present invention, the substrate is preferably a glass substrate, and is a glass substrate having on its surface at least one film selected from a metal film, a semiconductor film, a conductive film and an insulating film. is also preferred. The constituent metal of the metal film is, for example, one selected from gallium, iron, indium, aluminum, vanadium, titanium, chromium, rhodium, nickel, cobalt, zinc, magnesium, calcium, silicon, yttrium, strontium and barium, or Two or more kinds of metals and the like are included. Examples of constituent materials of the semiconductor film include simple elements such as silicon and germanium, compounds containing elements of Groups 3 to 5 and Groups 13 to 15 of the periodic table, metal oxides, and metal sulfides. , metal selenide, or metal nitride. Examples of the constituent material of the conductive film include tin-doped indium oxide (ITO), zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), tin oxide (SnO ₂ ), Examples include indium oxide (In ₂ O ₃ ) and tungsten oxide (WO ₃ ). More preferably it is a membrane. Materials constituting the insulating film include, for example, aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), silicon oxynitride (Si ₄ O ₅ N ₃ ) and the like.

The means for forming the metal film, the semiconductor film, the conductive film, and the insulating film is not particularly limited, and known means may be used. Examples of such forming means include mist CVD method, sputtering method, CVD method (vapor phase growth method), SPD method (spray pyrolysis deposition method), vapor deposition method, ALD (atomic layer deposition) method, coating method ( For example, dipping, dropping, doctor blade, inkjet, spin coating, brush coating, spray coating, roll coater, air knife coating, curtain coating, wire bar coating, gravure coating, inkjet coating, etc.).

Further, in the embodiment of the present invention, the core layer and the clad layer may be formed directly on the substrate, or may be formed via other layers such as a buffer layer (buffer layer) and a stress relaxation layer. A film may be formed. The means for forming other layers such as the buffer layer (buffer layer) and the stress relaxation layer is not particularly limited, and known means may be used. In the embodiment of the present invention, the mist CVD method is preferred.

In the embodiment of the present invention, the shape of the optical waveguide is not particularly limited, and may be a known shape. Examples of the shape of the optical waveguide include slab type, embedded type, semi-embedded type, and ridge type.

The order of forming the cladding layer and the core layer is not particularly limited. The lower clad layer 21a is formed on the substrate 23, the core layer 22 is formed on the obtained lower clad layer 21a, and the upper clad layer 22b is formed on the core layer 22, whereby the above-described It is preferred to manufacture optical waveguides. Further, for example, when manufacturing an embedded optical waveguide as shown in FIG. It is preferable to fabricate the optical waveguide by forming a pattern using a known pattern forming means or the like, then forming an upper cladding layer 21b on the core layer 22 and embedding the core layer 22 therein. . Examples of the pattern forming means include reactive ion etching, photolithography, imprinting, and photobleaching. In the embodiment of the present invention, it is also preferable to use the substrate 23 as the lower clad layer 21a.

Moreover, in the embodiment of the present invention, an electrode may be further provided on the laminate including the core layer and the clad layer. The electrodes are not particularly limited in the present invention, and may be known ones. Examples of the electrodes include ITO, gold, silver, chromium, aluminum, titanium, IZO, and aluminum-doped zinc oxide. Also, the means for forming the electrodes is not particularly limited, and known means can be used. Examples of means for forming the electrodes include a mist CVD method, a sputtering method, a CVD method (vapor deposition method), and an SPD method (spray pyrolysis deposition method).

By forming the film as described above, a high-quality optical waveguide having excellent optical properties such as transparency can be easily manufactured in a small number of steps. Also, the thicknesses of the core layer and the clad layer can be easily adjusted by adjusting the film formation time. Also, the refractive indices of the core layer and the clad layer can be easily adjusted by adjusting the film formation temperature or the like, adjusting the concentration of the oxidizing agent, or the like.

The optical waveguide obtained by the manufacturing method of the present invention is suitable for electronic devices such as mobile phones, game machines, router devices, WDM (wavelength division multiplexing) devices, personal computers, televisions, and home servers. can be used.

An embodiment of the present invention will be described below using an example of manufacturing a slab type optical waveguide shown in FIG. 2, but the present invention is not limited to this.

(Example 1)
1. Film Forming Apparatus A mist CVD apparatus (1) used in this example will be described with reference to FIG. The mist CVD apparatus (1) includes carrier gas sources (2a, 12a) for supplying a carrier gas, and flow control valves (3a, 13a) for adjusting the flow rate of the carrier gas sent from the carrier gas sources (2a, 12a). ), mist generating sources (4, 14) containing raw material solutions (4a, 14a), containers (5, 15) containing water (5a, 15a), and containers (5, 15) Ultrasonic vibrators (6, 16) attached to the bottom surface, a film forming chamber (7), supply pipes (9, 19) connecting mist generation sources (4, 14) to the vicinity of the substrate (10), At least a hot plate (8) installed in the deposition chamber (7). A substrate (10) is placed on the hot plate (8). There are two types of raw material solutions (4a, 14a), which are carrier gas sources (2a, 12a), carrier gas (dilution) sources (2b, 12b), and flow control valves (3a, 3b, 13a, 13b). , a mist source (4, 14), a container (5, 15), an ultrasonic transducer (6, 16) and a supply pipe (9, 19).

2. Preparation of raw material solution 2-1. Preparation of First Raw Material Solution Polysilazane and butyl acetate were mixed so that the concentration of polysilazane was 1.6% by volume to obtain a first raw material solution.
2-2. Preparation of Second Raw Material Solution Aqueous hydrogen peroxide and distilled water were mixed to obtain a second raw material solution (for core layer). Also, a second raw material solution (for clad layer) was obtained in which the concentration of aqueous hydrogen peroxide was lower than that of the second raw material solution (for core layer).

3. Film formation preparation 2-1. The first raw material solution 4 a obtained in 1. was accommodated in the first mist generation source 4 . In addition, the above 2-2. The second raw material solution (for core layer) 14a obtained in 1. was placed in the second mist generating source . Next, as the substrate 10, a glass substrate (lower clad layer) was placed on the hot plate 8, and the hot plate 8 was operated to raise the temperature of the substrate 10 to 70.degree. Next, the flow control valves 3a and 13a are opened to supply the carrier gas from the carrier gas supply means 2a and 12a, which are carrier gas sources, into the film forming chamber 7, and the atmosphere of the film forming chamber 7 is sufficiently filled with the carrier gas. After replacement, the carrier gas flow rate was adjusted to 1.0 L/min. Nitrogen was used as a carrier gas.

4. Formation of core layer Next, the ultrasonic oscillator 6 is vibrated at 2.4 MHz, and the vibration is propagated to the raw material solutions (4a, 14a) through the water (5a, 15a), thereby obtaining the raw material solutions (4a, 14a). ) was atomized to produce a mist (4b, 14b). A carrier gas was supplied to the mists (4b, 14b), and the mists (4b, 14b) were transported to the substrate 10 through the supply pipes (9, 19) by the carrier gas. The mist 4b and the mist 14b were mixed during transportation by the carrier gas and transported to the substrate 10. FIG. After transportation, the mist thermally reacted in the vicinity of the substrate 10 at 70° C. under atmospheric pressure to form a core layer on the substrate 10, thereby obtaining a substrate with a core layer. The thickness of the obtained core layer was 300 nm, and the film formation time was 20 minutes.

5. Formation of clad layer (upper clad layer) As the second raw material solution, the second raw material solution (for the clad layer) is used. Except for using the substrate with the core layer obtained in 4. above. A clad layer (upper clad layer) was formed on the substrate with the core layer by forming a film in the same manner as in the above. The obtained clad layer (upper clad layer) had a thickness of 300 nm, and the film formation time was 20 minutes.

6. Evaluation The obtained optical waveguide was excellent in adhesion between the glass substrate (lower clad layer) and the core layer, and between the core layer and the upper clad layer. Moreover, as a result of measuring the light transmittance of the obtained laminate using a spectrophotometer, the light transmittance was 89%, indicating excellent transparency.

INDUSTRIAL APPLICABILITY The film forming method of the present invention can be used in various manufacturing fields using optical waveguides, in which optical waveguides with excellent optical properties such as transparency can be manufactured with industrial advantage. According to the manufacturing method of the present invention, an optical waveguide can be manufactured at a low temperature, under atmospheric pressure, and in a non-vacuum, and a sintering process is not required. The optical waveguide thus formed can be suitably used in electronic equipment and the like.

1 mist CVD apparatus 2a (first) carrier gas source 3a (first) flow control valve 4 (first) mist generation source 4a (first) raw material solution 4b (first) mist 5 (first container 5a (first) water 6 (first) ultrasonic transducer 7 deposition chamber 8 hot plate 9 (first) supply pipe 10 substrate 12a (second) carrier gas source 13a (second (second) source of mist 14a (second) source solution 14b (second) mist 15 (second) container 15a (second) water 16 (second) over Sonic transducer 19 (second) supply pipe 21a lower clad layer 21b upper clad layer 22 core layer 23 substrate

Claims (8)

A method for manufacturing an optical waveguide by forming at least a core layer and a clad layer, wherein the core layer and the clad layer are formed by using a raw material solution containing a core layer precursor and a raw material solution containing a clad layer precursor. is atomized or dropletized, a carrier gas is supplied to each of the obtained mists or droplets , the carrier gas is used to transport the mist or the droplets to the substrate, and then the mist or the liquid A method for manufacturing an optical waveguide, characterized in that the droplet is thermally reacted on the substrate. 2. The manufacturing method according to claim 1, wherein the core layer precursor comprises a first metal. 3. The manufacturing method according to claim 2, wherein the first metal is a Group 14 metal of the periodic table. 4. The manufacturing method according to any one of claims 1 to 3, wherein the precursor of the clad layer contains a second metal. 5. The manufacturing method according to claim 4, wherein the second metal is a Group 14 metal of the periodic table. The manufacturing method according to any one of claims 1 to 5, wherein the atomization or the droplet formation is performed using ultrasonic vibration. The production method according to any one of claims 1 to 6, wherein the thermal reaction is performed in a non-oxygen atmosphere. The production method according to any one of claims 1 to 7, wherein the thermal reaction is carried out at a temperature of 150°C or less.

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