JPH0933742A - Production of optical waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of an optical waveguide by which the optical absorption loss in the core part of the optical waveguide is decreased and the number of production processes is reduced. SOLUTION: The production method includes the following processes. After a first photosensitive coating glass layer is formed on a substrate 10, the first photosensitive coating glass layer is heated and irradiated with light at one time to form a lower silica glass layer 14. Then a second photosensitive coating glass layer is formed on the lower silica glass layer, and the second photosensitive coating glass layer is partially irradiated with light and developed to form a core pattern 18. The core pattern 18 is treated with heavy water to form a core pattern 20 treated with heavy water. Then the whole surface of the lower silica glass layer 14 including the core pattern 20 treated with heavy water is coated with a third photosensitive coating glass layer 22 so as to embed the core pattern 20 treated with heavy water. The third photosensitive coating glass layer 22 is heated and irradiated with light at one time to form an upper silica glass layer 24. Thus, an optical waveguide 25 comprising the core pattern 20 treated with heavy water, the lower silica glass layer 14, and the upper silica glass layer 24 can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to light, electron beam, X
The present invention relates to a method for manufacturing an optical waveguide using a novel photosensitive coated glass which is sensitive to radiation such as rays and ion beams.

[0002]

2. Description of the Related Art In recent years, optical communication technology has been rapidly advancing in the advanced information communication society. Among them, optical transmission technology for transmitting an optical signal with low loss is a main line system connecting devices in a modularized device or an optical access system connecting various components and conversion elements for converting light to electricity or electricity to light. It is extremely important to reduce the loss at.

In the optical transmission technology, one of the causes of light loss is optical absorption loss due to a medium material used for optical transmission. As for the trunk line system for transmitting light between modularized devices, a low loss optical fiber that is almost close to the theoretical limit has been manufactured due to technological progress of the flame deposition method.
However, in the optical access system, it is difficult to reduce loss because light is absorbed by the transmission medium material forming the optical waveguide, and satisfactory low loss characteristics have not yet been obtained. In addition, in the optical access system, due to the adoption of the hybrid optical integrated technology, optical transmission between the optical components and the electrical components mounted on the substrate is required, so a technique for reducing the loss of the optical waveguide is required. Progress is being made in methods of manufacturing lossy optical waveguides. As one of the methods, there is a document (Japanese Journal o
f Applied Physics, Vol29, N
o. 12, 1990, pp. 2868-2874).

According to this document, an optical waveguide is formed on a substrate by a sol-gel method using tetramethoxysilane,
It is reported that the obtained SiO ₂ —GeO ₂ optical waveguide can realize low loss.

[0005]

However, the optical waveguide formed by the conventional sol-gel method has a light absorption loss of about 1 dB / cm when a predetermined light is incident on the optical waveguide and the emitted light is measured. . However, it is necessary to reduce the amount of optical absorption loss to 1 dB / cm or less in order to cope with higher integration and higher functionality of optical integrated circuits in the future.

Further, in the conventional manufacturing method, at least 1
Since one step is required and a long time is required for the step of adsorbing and desorbing the monomer, the dopant, and water, workability is poor, and thus mass productivity cannot be achieved. FIG.
10 to 10 are cross-sectional views for explaining steps of forming a conventional optical waveguide.

In the conventional method of manufacturing an optical waveguide, first, the substrate 50 is prepared ((A) of FIG. 8), and the substrate 50 is prepared.
A sol containing tetramethoxysilane, methanol, hydrochloric acid and ammonia is applied on the above to form a gelled porous silicate glass layer 52 ((B) of FIG. 8).

Next, the adsorbed water contained in the porous silicate glass layer 52 is removed under heating and reduced pressure to form a silicate glass layer 54 (FIG. 8C).

Next, the silicate glass layer 54 is dipped in a methyl acrylate monomer containing a sensitizer to form a silicate glass layer 56 containing monomers ((D) of FIG. 8).

Next, the monomer-containing silicate glass layer 56 is selectively irradiated with light to polymerize the monomer (to become a polymer) to form a latent image silicate glass layer 58 having a part of the silicate glass layer 56. ((A) of FIG. 9).

Next, the excess monomer in the latent image silicate glass layer 58 is removed under reduced pressure to form a latent image silicate glass layer 60 having a small amount of monomer ((B) in FIG. 9).

Next, germanium tetrachloride is doped in the portion not exposed to light (the portion which becomes the unexposed portion and the core) to form a silicate glass layer 62 containing germanium (FIG. 9C).

Next, part of the germanium tetrachloride in the germanium tetrachloride-doped silicate glass layer 62 is released to form a silicate glass layer 66 having a core portion 64 (FIG. 9 (D)). .

Next, the structure shown in FIG. 9D is impregnated with water to hydrolyze the germanium tetrachloride in the core portion 64, and the silicate glass layer 68 having the core 70 fixed thereon.
Are formed ((A) of FIG. 10).

Next, the adsorbed water contained in the silicate glass layer 68 is removed to form the film 72 with the core 70 (FIG. 1).
0 (B)).

Next, the polymer (polymerized with methyl acrylate) is thermally decomposed and removed to form the cladding layer 74 (FIG. 10C).

Next, the obtained structure is baked on a hot plate to form an optical waveguide 7 having a germanium core 72.
5 is formed ((D) of FIG. 10).

As can be understood from the steps described above, 11 steps were required as a manufacturing process for forming the conventional optical waveguide. Further, since the process steps include desorption and adsorption steps, there is a problem that the manufacturing time becomes long. Therefore, there has been a demand for a method of manufacturing an optical waveguide in which light absorption loss in the core portion of the optical waveguide is small and the number of manufacturing steps is reduced.

[0019]

According to the method of manufacturing an optical waveguide of the first invention, after the first photosensitive coated glass layer is formed on the substrate, the first photosensitive coated glass layer is heated and exposed to light. A step of simultaneously performing irradiation to form a lower silicate glass layer, and a second photosensitive coating glass layer is formed on the lower silicate glass layer, and then the lower silicate glass layer is partially irradiated with light. And a step of developing to form a core pattern, a step of treating the core pattern with heavy water to obtain a heavy water-treated core pattern, and then to the entire surface of the lower silicate glass layer including the heavy water-treated core pattern. After forming the third photosensitive coating glass layer so as to embed the heavy water treated core pattern, heating and light irradiation are simultaneously performed on the third photosensitive coating glass layer to form the upper silicate glass layer, Water treated core pattern, characterized in that it comprises a step of forming an optical waveguide comprising a lower silicate glass layer and upper silicate glass layer.

On the other hand, according to the method of manufacturing the optical waveguide of the second invention, the step of forming the first photosensitive coated glass layer on the substrate and the heating and the light irradiation to the first photosensitive coated glass layer are simultaneously performed. Performing a step of forming a lower silicate glass layer, forming a second photosensitive coated glass layer on the lower silicate glass layer, and partially irradiating the second photosensitive coated glass layer with light. A step of developing to form a core pattern; a step of forming a third photosensitive coated glass layer so that the core pattern is embedded in the entire surface of the lower silicate glass layer including the core pattern; A step of forming an optical waveguide comprising a core pattern, a lower silicate glass layer and an upper silicate glass layer by simultaneously performing heating and light irradiation on the coated glass layer to form an upper silicate glass layer, Heating and to mineralize waveguide,
And a step of sequentially performing heating for densification.

In carrying out the first and second inventions, preferably, the first and third photosensitive coated glass layers are
It is preferable to use a material containing poly (siloxane) obtained by hydrolyzing an alkoxysilane and then condensing it and an acid generator.

In carrying out the first and second inventions, preferably, the second photosensitive coated glass layer is obtained by copolymerizing an alkoxysilane and a group IV metal alkoxide with a metallosiloxane and an acid generator. It is preferable to use a material containing

[0023]

According to the optical waveguide manufacturing method of the first invention,
After forming the first photosensitive coated glass layer on the substrate, the coated glass layer is simultaneously heated and irradiated with light to form the lower silicate glass layer. Since the first photosensitive coated glass layer used here contains poly (siloxane) and an acid generator, an acid is generated by irradiation with light. The generated acid reacts with poly (siloxane) to form silicate glass. By subjecting this silicate glass to a heat treatment, the silanolization of the poly (siloxane) is further promoted to become an inorganic silicate glass.

Next, after forming a second photosensitive coated glass layer on the lower silicate glass layer, the second photosensitive coated glass layer is partially irradiated with light and developed to form a core pattern. Since the second photosensitive coated glass layer contains the metallopolysiloxane and the acid generator, the exposed portion reacts with the acid and the metallopolysiloxane to generate silanol by performing partial light irradiation, It becomes a silicic acid doped with a group IV metal. This silicic acid becomes insoluble in the developing solution, while the unexposed portion of the second photosensitive coated glass layer becomes soluble in the developing solution, so that the core pattern can be formed. Further, the core pattern is treated with heavy water to obtain a heavy water-treated core pattern. Since the core pattern is composed of silicic acid, when this core pattern is treated by being immersed in heavy water, for example, poly (siloxane) and heavy water (D ₂ O) react with each other to form a hydroxyl group (OH) of silicic acid. (Group) can be substituted with an OD group to obtain a heavy water treated core pattern. Core pattern from OH group to O
Since the peak position of the light absorption wavelength is shifted from the communication wavelength of 1.3 μm to the long wavelength side by substituting the D group, it overlaps with the light absorption loss peak wavelength in the 1.3 μm wavelength region as in the conventional case. Can be avoided. Therefore, it is possible to reduce the amount of light absorption loss when light enters the heavy water treated core pattern.

Further, after the third photosensitive coated glass layer is formed on the surface of the structure containing the heavy water treated core pattern so as to embed the heavy water treated core pattern, the third photosensitive coated glass layer is formed on the third photosensitive coated glass layer. By simultaneously performing heating and light irradiation to form the upper silicate glass layer,
An optical waveguide comprising a heavy water treated core pattern, a lower silicate glass layer and an upper silicate glass layer is formed. Since this third photosensitive coated glass layer uses the same layer as the above-mentioned first photosensitive coated glass layer, silanol is generated by irradiation with light and becomes silicic acid. Further, by heating, silanolization is further promoted to form an inorganic silicate glass.

According to the method of manufacturing an optical waveguide of the second invention, the step of forming the first photosensitive coated glass layer on the substrate and the heating and the light irradiation of the first photosensitive coated glass layer are performed simultaneously. A step of forming a lower silicate glass layer, a step of forming a second photosensitive coated glass layer on the lower silicate glass layer, and partial light irradiation and development of the second photosensitive coated glass layer. To form a core pattern, a step of forming a third photosensitive coating glass layer so that the core pattern is embedded in the entire surface of the lower silicate glass layer including the core pattern, and a third photosensitive coating. A step of forming an optical waveguide comprising a core pattern, a lower silicate glass layer and an upper silicate glass layer by simultaneously heating and irradiating the glass layer to form an upper silicate glass layer; It includes heating and for mineralization, sequentially performing the steps of heating for densifying. Thus, the number of steps of the second invention is eight, which is one of the conventional ones.
The number of steps is reduced by 3 steps as compared with 1 step. Further, since the manufacturing process of the second invention does not include the adsorption and desorption processes as in the conventional case, the manufacturing time can be shortened as compared with the conventional case.

[0027]

Embodiments of the method for manufacturing an optical waveguide according to the present invention will be described below with reference to the drawings. The materials used and the numerical conditions such as the amount of material used, the processing time, the temperature, and the film thickness described in the following description are only suitable examples within the scope of the present invention. Therefore, it should be understood that the present invention is not limited to only these conditions.

1. 1. Method of manufacturing optical waveguide of first invention 1-1. First Embodiment In the first embodiment of the present invention, a method of manufacturing an optical waveguide will be described for the purpose of reducing the loss of the optical waveguide.

1-1-1. Preparation of Resist Solution First, preparation of resist solutions for the first, second and third photosensitive coated glass layers used in this example will be described. Here, since the same coating glass solution is used for the first and third photosensitive coating glass layers,
I will explain in a lump.

The coated glass used for the first and third photosensitive coated glass layers was prepared by partially hydrolyzing tetramethoxysilane and then condensing it with poly (siloxane) and 4-phenylthio as an acid generator. Phenyldiphenylsulfonium triflate and methyl isobutyl ketone (M
IBK: dissolved in a solvent) and mixed. This mixed solution is used as a coating glass solution. In addition, 4-phenylthiophenyldiphenylsulfonium triflate is poly (siloxane)
To 5 wt%.

Next, the resist used for the second photosensitive coated glass layer is prepared as follows.

80 mol% of tetramethoxysilane and 20 mol% of tetramethoxygermane are partially hydrolyzed,
Then, the condensed metallopolysiloxane and 4-phenylthiophenyldiphenylsulfonium triflate which is an acid generator for the metallopolysiloxane are dissolved and mixed in MIBK. This mixed solution is used as a resist solution for forming the second photosensitive coated glass layer. At this time, 4-phenylthiophenyldiphenylsulfonium triflate is 5w with respect to the metallopolysiloxane.
The ratio is t%.

1-1-2. Method of Manufacturing Optical Waveguide In this embodiment, a silicon substrate is used as the substrate 10 ((A) of FIG. 1). After spin-coating the resist solution of the first photosensitive coated glass layer described in section 1-1-1 on this substrate 10, the substrate containing the coating film was pre-baked (100 ° C., 2 minutes) on a hot plate. The first photosensitive coated glass layer 12 is formed. Here, the film thickness of the first photosensitive coating glass layer 12 is about 0.6 μm ((B) of FIG. 1).

Next, the obtained first photosensitive coated glass layer 1
While heating the structure containing 2 (150 ° C), ultraviolet rays (U
V) The entire surface of the first photosensitive coating glass layer 12 is irradiated with light by using a curing device (10 minutes) to expose the lower silicate glass layer 1
4 is formed ((C) of FIG. 1). The thickness of the lower silicate glass layer 14 is about 5.0 μm here. Further, in this embodiment, the lower silicate glass layer 14 is also referred to as an underclad layer.

Next, on the lower silicate glass layer 14, 1-
After spin-coating the coating glass solution for the second photosensitive coating glass layer described in Section 1-1, the substrate containing the coating film is pre-baked (100 ° C., 2 minutes) on a hot plate to form the second photosensitive coating glass. The layer 16 is formed ((D) of FIG. 1).
Here, the film thickness of the second photosensitive coated glass layer 16 after prebaking is set to about 1.2 μm.

Next, an evaluation pattern is drawn by partially irradiating the second photosensitive coated glass layer with ultraviolet rays having an exposure dose of 10 mJ / cm ² using a deep UV exposure machine. Then, the obtained sample is baked on a hot plate (120 ° C., 2 minutes) and then developed in anisole (developing solution). At this time, the light-exposed portion remains without being dissolved in the developing solution, and the unexposed portion is removed to form the core pattern 18 ((A) in FIG. 2). The core pattern 18 has a thickness of about 1.0 μm here.

Next, the core pattern 18 is immersed in heavy water. Therefore, in this embodiment, this core pattern 1
After immersing the structure containing 8 in boiling heavy water for about 50 hours, it is taken out of the heavy water and baked on a hot plate (200 ° C., 10 minutes) to form the heavy water treated core pattern 20 ( FIG. 2B). The heavy water-treated core pattern 20 obtained here has the property of shifting the position of the light absorption peak wavelength to the long wavelength side when, for example, semiconductor laser light (wavelength of 1.3 μm) is incident.
Although the structure was immersed in boiling heavy water in this example, the following treatment may be performed to shorten the substitution reaction time.

In order to accelerate the reaction of substituting the OH group contained in the silicic acid, which is the material of the core pattern, with the OD group, the temperature of the structure containing the core pattern is increased while being pressurized. By such a method, the time required for OD replacement can be shortened. FIG. 4 is a diagram for explaining a process in which silicic acid, which is a material of the core pattern 18, reacts with heavy water and is replaced with deuterium.

The silicic acid reacts with heavy water to replace the hydrogen atom of silanol in the silicic acid with deuterium by an equilibrium reaction to generate silicic acid substituted with deuterium and water containing heavy water. At this time, the equilibrium reaction between silicic acid and heavy water is predominantly biased to the right as shown in FIG. It can be replaced by deuterium. Thus, for example, when the semiconductor laser light (1.3 μm wavelength) is incident on the heavy water-treated core pattern 20 replaced with deuterium, the peak position of the light absorption wavelength shifts to the long wavelength side, and therefore, 1.3 μm Since the overlap with the communication wavelength can be avoided, the loss of emitted light intensity is also reduced.

Next, the heavy water treated core pattern 20 is formed on the entire surface of the structure having the heavy water treated core pattern 20.
To form a third photosensitive coating glass layer 22 by embedding (FIG. 2C). Since the material of the third photosensitive coating glass layer used at this time is the same as that of the first photosensitive coating glass layer 12 already described, the resist solution and the coating method are the same as the conditions of FIG.

Next, the obtained third photosensitive coated glass layer 2
The upper surface silicate glass layer 24 is formed by exposing the structure containing 2 to the entire surface (10 minutes) while heating (150 ° C.) (FIG. 2D). Here, it is preferable that the upper silicate glass layer 24 is formed to have a thickness slightly larger than 5 μm.
Further, in this embodiment, the upper silicate glass layer 24 is also referred to as an overclad layer. Further, here, the lower silicate glass layer 14, the upper silicate glass layer 24, and the heavy water-treated core pattern 20 are collectively referred to as an optical waveguide 25.

Next, since the heavy water treated core pattern 20 and the upper silicate glass layer 24 contain a small amount of organic matter, the structure containing the upper silicate glass layer 24 is baked (400) on a hot plate. The organic content-removed core pattern 20a and the upper silicate glass layer 26 are formed by removing the organic content (° C., 10 minutes) ((A) of FIG. 3).
Incidentally, here, the upper silicate glass layer 26 excluding the organic component is used.
Is also referred to as a clad layer from which organic components have been removed.

Next, the substrate 10 including the optical waveguide 27 is loaded into an annealing furnace in an oxygen atmosphere and heated (850 ° C., 1 ° C.).
Time) to form a densified optical waveguide 28 including a densified silicate glass layer (also referred to as a dense cladding layer) 26a and a densified dense core pattern 20b (FIG. 3B).

After assembling the obtained optical waveguide into parts,
An evaluation test of the optical waveguide was performed using a semiconductor laser beam having a wavelength of 1.3 μm. As the evaluation method, laser light is made incident from one end face of the optical waveguide and the light intensity emitted from the other end face of the optical waveguide is measured to measure the light absorption loss. As a result, the amount of light absorption loss is 0.05 dB / c
The value of m was obtained.

As can be understood from this result, it was found that the light absorption loss was reduced to 1/20 of that in the conventional case.

2. Method for Manufacturing Optical Waveguide of Second Invention Next, an embodiment of the second invention will be described with reference to FIGS. In this embodiment, the light absorption loss is the first invention first.
Although it is slightly larger than that of the embodiment, it is intended to reduce the number of steps. 5, 6 and 7 are sectional views for explaining the steps of manufacturing the optical waveguide of this embodiment.

In the second embodiment, a silicon substrate is used as the substrate 10 ((A) of FIG. 5). First on this substrate 10
The first photosensitive coating glass layer 12 is formed using the coating glass solution prepared in the paragraph 1-1-1 described in the first embodiment of the invention ((B) of FIG. 5), and then heat exposure is performed simultaneously. To form the lower silicate glass layer 14 ((C) of FIG. 5).

Next, after forming the second photosensitive coating glass layer 16 on the lower silicate glass layer 14, after partially irradiating light, the second photosensitive coating glass layer 16 is developed. The core pattern 18 is formed ((A) of FIG. 6). The steps up to this point are the same as those of the first embodiment of the invention. Therefore, detailed description is omitted here.

Next, in this example, the resist solution for the third photosensitive coated glass layer prepared in the paragraph 1-1-1 described in the first example of the first invention was added to the lower side containing the core pattern 18. The core pattern 18 is embedded on the entire surface of the silicate glass layer 14 by spin coating so that the structure containing the coating film is baked (100 ° C., 2 minutes) on a hot plate to form a second layer.
The photosensitive coated glass layer 22 is formed ((B) of FIG. 6).

Then, the entire surface of the third photosensitive coating glass layer 22 is irradiated with light (10 minutes) while heating (150 ° C.) using an ultraviolet (UV) curing device to form the upper silicate glass layer 24. ((C) of FIG. 6). Here, the lower silicate glass layer 14, the upper silicate glass layer 24, and the core pattern 18 are collectively referred to as an optical waveguide 25.

Next, the structure containing the upper silicate glass layer 24 is baked on a hot plate (400 ° C., 10 minutes).
To remove the organic component (also referred to as the organic component-removed core pattern) 19 and the silicate glass layer 26.
Are formed ((A) of FIG. 7). The silicate glass layer 26 excluding the organic component is also referred to as a clad layer here. In addition, in this embodiment, the organic-removed core pattern 19 is used.
And the cladding layer 26 are collectively referred to as the optical waveguide 2 from which organic components have been removed.
It is called 9.

Next, after the structure containing the optical waveguide 29 is loaded into the annealing furnace, the furnace is heated to an oxygen atmosphere and heated (850).
A core pattern (also referred to as a densified core pattern) 19a that has been densified by performing the treatment at 1 ° C. for 1 hour and a silicate glass layer (also referred to as a dense clad layer) 26 that has been densified.
a is formed ((B) of FIG. 7). Here, the densified core pattern 19a and the dense clad layer 26a are collectively referred to as the densified optical waveguide 30.

As can be seen from the above process, the second
In the embodiment of the invention, the number of manufacturing steps of the optical waveguide can be reduced because the step of immersing in the heavy water of the first embodiment of the first invention is excluded. Further, in this embodiment, the optical waveguide can be formed by 8 steps. Therefore, the number of steps can be reduced by 3 steps as compared with the conventional example (11 steps). Further, since the adsorption and desorption process is not included in the process of this embodiment as in the conventional case, the process time can be shortened. Therefore, mass production of products can be achieved.

Further, after the optical waveguide obtained in this example was assembled into a component, an evaluation test of the optical waveguide was conducted using a semiconductor laser beam having a wavelength of 1.3 μm. Laser absorption was made incident from one end face of the optical waveguide, and the light intensity was measured from the other end face of the optical waveguide to measure the light absorption loss. As a result, the amount of light absorption loss was 0.1 dB / cm.

As can be understood from this result, in the embodiment of the second invention, the value of the light absorption loss increases because the deuterium is not replaced by heavy water, but this is not a problem in practical use.

In the above-mentioned examples, germanium prepared by mixing tetraalkoxygermane into the coating glass solution for forming the third photosensitive coating glass layer was used, but the material is not limited to this material. No, for example I
Titanium (Ti), Zirconium (Zr) as Group V metal
Alternatively, a metallopolysiloxane copolymerized with an alkoxysilane using a metal alkoxide containing one element selected from tin and tin (Sn) may be used.

Further, tetraalkoxysilane was used as the resist material for the first and third photosensitive coated glass layers,
The material is not limited to this, and a tetrafunctional silane having the same properties as the tetraalkoxysilane may be partially hydrolyzed and then condensed to form poly (siloxane). .

As the resist for the first and third photosensitive coated glass layers, commercially available coated glass such as OC can be used.
A resist solution may be prepared by dissolving this material and the acid generator in MISK using D (manufactured by Tokyo Ohka Co., Ltd.) or Akugras (manufactured by Allied Signal Co., Ltd.).

As the resist for the first and third photosensitive coated glass layers, the silicone resin composition and the acid generator according to Japanese Patent Application No. 6-54224 by the inventors of this application may be used. .

[0060]

As is apparent from the above description, in the method of manufacturing an optical waveguide of the first invention, after forming the core pattern, the core pattern is treated with heavy water. In such a step, the silicic acid forming the core pattern reacts with heavy water to replace the hydrogen atom of the hydroxyl group with deuterium to obtain a heavy water-treated core pattern. Therefore, when a heavy water treated core pattern is embedded with a lower silicate glass layer and an upper silicate glass layer to form an optical waveguide, when a communication wavelength of 1.3 μm is incident on the core pattern, a light absorption loss peak is generated. Since the wavelength shifts to the longer wavelength side than the wavelength of 1.3 μm, an optical waveguide with low loss can be formed. Further, by sequentially performing heating for making the optical waveguide inorganic and heating for making it dense,
Organic components contained in the optical waveguide can be removed or the optical waveguide can be densified.

Further, according to the method of manufacturing an optical waveguide of the second invention, the optical waveguide can be manufactured in 8 steps as described above, so that the number of steps can be reduced as compared with the conventional method (11 steps). it can. Therefore, since the number of processes and the process time can be reduced, mass production can be achieved, and the product cost can be reduced. In addition, the process of the embodiment of the second invention does not require the adsorption and desorption processes as in the prior art, so that the process time can be greatly shortened.

[Brief description of drawings]

FIG. 1A to FIG. 1D are process drawings provided for explaining a manufacturing process of an optical waveguide of a first embodiment of the first invention.

FIG. 2A to FIG. 2D are process drawings provided to explain the manufacturing process of the optical waveguide following FIG.

3 (A) to 3 (B) are process drawings provided for explaining the manufacturing process of the optical waveguide, following FIG.

FIG. 4 is a diagram for explaining a reaction for producing deuterium-substituted silicic acid from silicic acid and heavy water.

5A to 5D are process drawings provided for explaining a manufacturing process of the optical waveguide according to the example of the second invention.

6A to 6C are process diagrams provided for explaining the manufacturing process of the optical waveguide, following FIG.

7 (A) to (B) are process diagrams provided for explaining the manufacturing process of the optical waveguide, following FIG. 6.

FIG. 8A to FIG. 8D are process drawings provided for explaining a conventional manufacturing process of an optical waveguide.

9A to 9D are process diagrams provided for explaining the manufacturing process, following FIG. 8.

10 (A) to (D) are process drawings provided for explaining the manufacturing process, following FIG. 9.

[Explanation of symbols]

 10: Silicon substrate 12: First photosensitive coated glass layer 14: Lower silicate glass layer 16: Second photosensitive coated glass layer 18: Core pattern 20: Heavy water treated core pattern 22: Third photosensitive coated glass layer 24: Upper silicate glass layer 26: Silicate glass layer without organic components 26a: Densified silicate glass layer 27: Optical waveguide with organic components removed 30: Densified optical waveguide

Claims (4)

[Claims] 1. (a) After forming a first photosensitive coated glass layer on a substrate, heating and light irradiation are simultaneously performed on the first photosensitive coated glass layer to form a lower silicate glass layer. And (b) forming a second photosensitive coated glass layer on the lower silicate glass layer, and then performing partial light irradiation and development on the second photosensitive coated glass layer to form a core pattern. And (c) a step of treating the core pattern with heavy water to obtain a heavy water treated core pattern, and (d) thereafter, covering the entire surface of the lower silicate glass layer including the heavy water treated core pattern. Forming a third photosensitive coated glass layer so as to embed the heavy water treated core pattern, and then simultaneously performing heating and light irradiation on the third photosensitive coated glass layer to form an upper silicate glass layer. Due to the heavy water And a step of forming an optical waveguide comprising the treated core pattern, the lower silicate glass layer and the upper silicate glass layer. 2. The method for manufacturing an optical waveguide according to claim 1, wherein, as the post-step of (d), heating for mineralizing the optical waveguide and heating for densifying are sequentially performed. A method of manufacturing an optical waveguide, comprising the steps of: 3. The method for producing an optical waveguide according to claim 1, wherein the second photosensitive coating glass layer in the step (b) is obtained by copolymerizing an alkoxysilane and a group IV metal alkoxide. A method for manufacturing an optical waveguide, which is characterized by being formed of a material containing polysiloxane and an acid generator. 4. A lower silicate glass comprising: (a) forming a first photosensitive coated glass layer on a substrate; and (b) simultaneously heating and irradiating the first photosensitive coated glass layer. A step of forming a layer, (c) a step of forming a second photosensitive coated glass layer on the lower silicate glass layer, and (d) partial light irradiation of the second photosensitive coated glass layer and Developing to form a core pattern, and (e) forming the third photosensitive coating glass layer by embedding the core pattern in the entire surface of the lower silicate glass layer including the core pattern. And (f) heating and irradiating the third photosensitive coated glass layer at the same time to form an upper silicate glass layer, whereby the core pattern, the lower silicate glass layer and the upper silicate glass layer are formed. An optical waveguide consisting of a glass layer Process and, (g) and heated to mineralize the optical waveguide, optical waveguide manufacturing method which comprises a step of successively performing the heating for densification of formed.