JPH11237516A - Quartz glass waveguide and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a waveguide of a low loss with a large difference of specified refractive index by heating the waveguide in a process of heat treatment to heat to a specified temp. range in the production process of the waveguide so that a part of fluorine is diffused and transferred from a core embedding layer in contact with a core. SOLUTION: This waveguide has such a structure that intermediate layers 3, 5 which is embedded so as to cover the periphery of a core 4 having an almost square cross section, and SiO2 -based clad layers 2, 6 which is embedded so as to cover the periphery of the intermediate layers 3, 5 (core embedding layers) are formed on a substrate 1. The core 4 consists of a SiO2 glass or SiO2 Ny Hz glass having high refractive index with addition of a component to control the refractive index (dopants to increase the refractive index such as GeO2 and TiO2 ). The intermediate layers consist of a fluorine-doped SiO2 glass having a low refractive index. In the production process of the waveguide above described, the waveguide is heated once or more times in a heat treatment process to the temp, range of 800 to 1200 deg.C so that a part of fluorine is diffused and transferred from the core embedding layers 3, 5 in contact with the core.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silica glass waveguide having a high refractive index core and a low refractive index layer covering the core, and a method of manufacturing the same.

[0002]

BACKGROUND OF THE INVENTION a conventional quartz-based glass waveguide arrangement, for the core and a high refractive index, the refractive index as a glass of the core-improving component added SiO ₂ based glass or S
iOxNyHz-based glass is used, and SiO ₂ -based glass is used as a constituent glass of a buried layer covering the core. Examples of the refractive index improving component include refractive index controlling dopants such as GeO ₂ and TiO ₂ .

[0003] The above-mentioned problems of the conventional silica glass waveguide are caused by absorption in the 1.39 μm band caused by OH groups in the core and 1.5 μm in wavelength caused by Si—H groups and NH groups.
This is a loss due to absorption in the m-band, and low loss is required to expand the application range of the silica glass waveguide.

As a conventional method of reducing the loss, a high-temperature heat treatment is performed after forming a core or after forming a cladding layer in which a core is buried in a manufacturing process of a silica-based glass waveguide, thereby removing H in the core to remove an OH group. , Si-H group, NH
It is common to try to remove the group.

[0005]

However, when H in the core is removed by the high-temperature heat treatment, 1200 ° C.
Since a higher temperature is required, the core or the like is thermally deformed, so that desired glass waveguide characteristics cannot be obtained. When the temperature of the heat treatment is set to 1200 ° C. or less, O
H group, Si—H group, and N—H group remain, and the desired reduction in loss cannot be achieved.

Accordingly, the present invention provides a quartz glass waveguide having a high relative refractive index difference and a low loss, and a method for manufacturing the same, which aims to effectively solve these problems.

[0007]

A waveguide according to the present invention comprises a substrate and a core buried layer formed of a high refractive index glass having a substantially rectangular cross section and formed of a low refractive index glass formed on the substrate. In the quartz-based glass waveguide including the structure embedded so as to be covered with, the high-refractive-index glass is a SiO ₂ -based glass or a SiOxNyHz-based glass to which a refractive index improving component is added, and the low refractive index glass is a fluorine-added SiO _2. Glass, and 800 during the manufacturing process of the waveguide.
A quartz glass waveguide in which a part of fluorine is diffused / transferred from the core buried layer which is heated once or twice or more by a heat treatment step of heating to a temperature range of 1 to 1200 ° C. is there.

According to the method of manufacturing a waveguide of the present invention, a core-embedded low-refractive-index glass layer made of a fluorine-added SiO ₂ glass having a substantially rectangular cross section and a refractive-index-improving component-added SiO
_{In a} method for manufacturing a quartz-based glass waveguide having a structure in which a high-refractive-index glass core made of _two- system glass or SiOxNyHz-based glass is embedded, SiO ₂
Forming or not forming a system glass layer, forming a lower film for the core embedded low refractive index glass layer, and forming a core film for the high refractive index core on the formed lower film. Forming the core having a substantially rectangular cross-section from the formed core film, and covering both side surfaces and an upper surface of the core having the formed substantially rectangular cross-section, so as to cover the low refractive index glass for embedding the core. Forming an upper film for the layer, embedding the core with the upper film and the lower film for the low refractive index glass layer, and after forming the core film or after forming the core film and the core After the formation of the upper film for the burying glass layer or after the formation of the core film and the formation of the entire waveguide structure, a heat treatment is performed in a temperature range of 800 ° C. to 1200 ° C. in the low refractive index glass for burying the core. Part of fluorine diffuses into high refractive index glass core A method for producing a silica-based glass waveguide shifting.

In the present invention, a core made of high refractive index glass is selected as the core, and a fluorine-added SiO ₂ glass layer is selected as the low refractive index glass layer for embedding the core. A glass layer made of SiO ₂ -based glass is selected as a glass layer covering the low-refractive-index glass layer to form a prescribed laminated structure, and one or two glass layers provided during the step of forming the laminated structure are selected. By heating through a heat treatment step of more than one piece, part of the fluorine in the low refractive index glass layer for core embedding diffuses into the core in contact therewith.
Be migrated.

In the description of the embodiments below, the low refractive index glass layer for embedding the core is referred to as an intermediate layer.
The glass layer covering the core-embedding low refractive index glass layer may be referred to as a cladding layer.

In the present invention, the core is made of a SiO ₂ -based glass or a SiOxN
Fluorine-doped SiO2 made of yHz-based glass and covering the core by heat treatment during the manufacturing process of the quartz-based glass waveguide
₂ Includes fluorine diffused and migrated from buried layer.

The substrate of the present invention includes a SiO ₂ glass substrate and a Si substrate.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A group of embodied waveguides according to the present invention comprises a substrate and a core made of high refractive index glass having a substantially rectangular cross section formed on the substrate. In a quartz glass waveguide including a structure embedded so as to be covered with a core embedding layer made of a refractive index glass, the high refractive index glass is a refractive index improving component-added SiO ₂ glass or a SiOxNyHz glass. A structure comprising a core and a core burying layer covering the core has a structure further covered with SiO ₂ -based glass, and is heated to a temperature range of 800 ° C. to 1200 ° C. during the manufacturing process of the waveguide. Is heated one or more times by a heat treatment step to diffuse and partially diffuse fluorine from the core burying layer with which the core comes into contact.
This is a quartz-based glass waveguide that has been migrated.

A group of embodied waveguides according to the present invention comprises a substrate and a core made of a high-refractive-index glass having a substantially rectangular cross section formed on the substrate, made of a low-refractive-index glass. in silica-based glass waveguide including a structure is embedded, so as to cover the core buried layer made, the high refractive index glass is improved refractive index component added SiO ₂ based glass or SiO
xNyHz-based glass, wherein the low-refractive-index glass is a fluorine-added SiO ₂ -based glass, and the core and the burying layer covering the core form a structure having a substantially rectangular outer peripheral cross section. Is covered with SiO ₂ -based glass, and is heated once or twice or more by a heat treatment step of heating to a temperature range of 800 ° C. to 1200 ° C. during the manufacturing process of the waveguide, and the core comes into contact therewith. This is a quartz glass waveguide in which a part of fluorine is diffused and transferred from the core burying layer.

A group of embodied waveguides according to the present invention comprises a core made of a high-refractive-index glass having a substantially rectangular cross-section formed on a substrate, and a core made of a low-refractive-index glass. In a waveguide having a structure in which the outer periphery of a structure having a substantially rectangular outer peripheral cross section covered with a core burying layer is covered with a SiO ₂ glass layer, the substrate is a SiO ₂ glass substrate, and the high refractive index glass Is the refractive index improving component added SiO
A system glass or SiOxNyHz glass, the low refractive index glass is fluorine added SiO ₂ -based glass, the SiO ₂ based glass layer was formed so as to cover both sides and the top surface of the substrate and the structure SiO is composed of a ₂ glass layer upper layer, and the waveguide in the manufacturing process of, above it is heated one or more times by a heat treatment step of heating to a temperature range of 800 ° C. to 1200 ° C. and to contact the core Diffusion of part of fluorine from core buried layer
This is a quartz-based glass waveguide that has been migrated.

A group of embodied waveguides according to the present invention comprises a core made of a high-refractive-index glass having a substantially rectangular cross-section and formed on a substrate, and a core made of a low-refractive-index glass. In a waveguide having a structure in which the outer periphery of a structure having a substantially rectangular outer peripheral cross section covered with a core burying layer is covered with a SiO ₂ -based glass layer, the substrate is a Si substrate, and the SiO ₂ -based glass is A film is formed, the high refractive index glass is a SiO ₂ -based glass or SiOxNyHz-based glass added with a refractive index improving component, the low refractive index glass is a fluorine-added SiO ₂ -based glass,
SiO _{2 2} based glass layer formed on the Si substrate
A SiO ₂ -based glass upper film formed so as to cover both side surfaces and the upper surface of the structure, and
And 800 ° C. to 1200 ° C. during the manufacturing process of the waveguide.
1 or 2 depending on the heat treatment step of heating to the temperature range of
This is a quartz glass waveguide in which a part of fluorine is diffused and transferred from the core buried layer, which is heated more than once and the core is in contact with the core.

A method of manufacturing a waveguide according to the present invention, which is embodied as a group, comprises a step of forming a fluorine-added SiO ₂ on a substrate.
A low refractive index glass layer for embedding a core made of a system glass, having a substantially rectangular cross section, and forming a structure in which a high refractive index glass core made of a SiO ₂ system glass or SiOxNyHz system glass added with a refractive index improving component is embedded. In the method for manufacturing a silica-based glass waveguide, a lower film for the core-embedded low-refractive-index glass layer is formed by forming or not forming an SiO ₂ -based glass layer on the substrate. Forming a core film for the high refractive index core on the lower film, forming the core having a substantially rectangular cross section from the formed core film, and forming the core having a substantially rectangular cross section. An upper film for the core embedding low refractive index glass layer is formed so as to cover both side surfaces and the upper surface, and the core is embedded with the upper film and the lower film for the low refractive index glass layer. In addition, the above A) forming an upper film for the SiO ₂ -based glass layer on the upper film for the low refractive index glass layer for embedding, and heat-treating the core film after forming the core film in a temperature range of 800 to 1200 ° C. This is a method for manufacturing a quartz-based glass waveguide in which part of fluorine in a low-refractive-index glass is diffused and transferred into a high-refractive-index glass core.

A group of embodied methods for manufacturing a waveguide according to the present invention includes a low-refractive-index glass layer for embedding a core made of a fluorine-added SiO ₂ glass having a substantially rectangular cross section on a substrate. In the method for manufacturing a quartz glass waveguide having a structure in which a high refractive index glass core made of SiO ₂ glass or SiOxNyHz glass having a refractive index improving component is embedded, the SiO ₂ glass is formed on the substrate. Forming or not forming a glass layer, forming a lower film for the core embedded low refractive index glass layer, forming a core film for the high refractive index core on the formed lower film, From the formed core film and the lower film, the core having a substantially rectangular cross-section and the lower part of the low-refractive index glass layer for embedding the core having substantially the same width in contact with the lower surface thereof are formed, and the substantially rectangular shape is formed. The core having a cross section and the core Forming an upper film for a core-embedded low-refractive-index glass layer covering both sides and an upper surface of a structure comprising the lower part of the core-embedded low-refractive-index glass layer, and forming the core from the formed structure. Is formed with a substantially rectangular cross section in which the outer periphery is covered with the core embedding low refractive index glass layer, and both sides and the upper surface of the formed structure are formed of SiO 2.
A part of fluorine in the low-refractive-index glass is subjected to heat treatment in a temperature range of 800 ° C. to 1200 ° C. after the core film is formed so as to cover and bury the upper film for the _second system glass layer. This is a method for manufacturing a silica-based glass waveguide that is diffused and transferred into a core.

A group of embodied methods for manufacturing a waveguide according to the present invention comprises a low-refractive-index glass layer for embedding a core made of fluorine-containing SiO ₂ -based glass having a substantially rectangular cross section on a substrate. In the method for manufacturing a quartz glass waveguide having a structure in which a high refractive index glass core made of SiO ₂ glass or SiOxNyHz glass having a refractive index improving component is embedded, the SiO ₂ glass is formed on the substrate. Forming or not forming a glass layer, forming a lower film for the core embedded low refractive index glass layer, forming a core film for the high refractive index core on the formed lower film, The core embedding low-refractive-index glass layer is formed so as to form the core having a substantially rectangular cross section from the formed core film, and to cover both side surfaces and an upper surface of the formed core having a substantially rectangular cross section. Form upper film for The core is embedded in the upper film and the lower film for the core embedding low refractive index glass layer, and heat treatment is performed in a temperature range of 800 ° C. to 1200 ° C. after the formation of the core film. Some of the fluorine contained therein diffuses and migrates into the high-refractive-index glass core.
This is a method for manufacturing a quartz-based glass waveguide that is heat-treated in a temperature range of 00 ° C to 1200 ° C.

A group of embodied methods of manufacturing a waveguide according to the present invention is a low refractive index glass layer for embedding a core made of a fluorine-added SiO ₂ glass having a substantially rectangular cross section on a substrate. In the method for manufacturing a quartz glass waveguide having a structure in which a high refractive index glass core made of SiO ₂ glass or SiOxNyHz glass having a refractive index improving component is embedded, the SiO ₂ glass is formed on the substrate. Forming or not forming a glass layer, forming a lower film for the core embedded low refractive index glass layer, forming a core film for the high refractive index core on the formed lower film, The core embedding low-refractive-index glass layer is formed so as to form the core having a substantially rectangular cross section from the formed core film, and to cover both side surfaces and an upper surface of the formed core having a substantially rectangular cross section. Form upper film for The core so as to fill the upper film and the lower film for the low refractive index glass layer for the core embedded Te, the SiO ₂ further formed on the upper layer for the core embedding the low-refractive index glass layer Forming an upper film for the system glass layer, and forming the core film at 800 ° C. to 1200 ° C.
Diffusion and is shifted to a high refractive index glass core in a portion of the fluorine in the low refractive index glass core embedded in a heat treatment at a temperature range, further also after the formation of the upper layer for the SiO ₂ based glass layer 800 This is a method for manufacturing a quartz-based glass waveguide that is heat-treated in a temperature range of from 1C to 1200C.

A group of embodied methods for manufacturing a waveguide according to the present invention includes a low refractive index glass layer for embedding a core made of a fluorine-added SiO ₂ glass having a substantially rectangular cross section on a substrate. In the method for manufacturing a quartz glass waveguide having a structure in which a high refractive index glass core made of SiO ₂ glass or SiOxNyHz glass having a refractive index improving component is embedded, the SiO ₂ glass is formed on the substrate. Forming or not forming a glass layer, forming a lower film for the core embedded low refractive index glass layer, forming a core film for the high refractive index core on the formed lower film, From the formed core film and the lower film, the core having a substantially rectangular cross-section and the lower part of the low-refractive index glass layer for embedding the core having substantially the same width in contact with the lower surface thereof are formed, and the substantially rectangular shape is formed. The core having a cross section and the core Forming an upper film for the core-embedded low-refractive-index glass layer covering both sides and the upper surface of the structure comprising the lower part for the core-embedded low-refractive-index glass layer, and forming the upper film from the formed structure. Forming a structure having a substantially rectangular cross section in which the outer periphery of the core is covered with the core embedding low-refractive-index glass layer, and forming both sides and the upper surface of the formed structure with the Si
A part of fluorine in the low-refractive-index glass is subjected to a high-refractive-index glass by covering with an upper film for an O ₂ -based glass layer and embedding it, and after forming the core film, heat-treating in a temperature range of 800 ° C. to 1200 ° C. Diffusion and transfer into the glass core
800 ° C. to 120 ° C. even after the formation of the upper film for the _second glass layer
This is a method for manufacturing a quartz glass waveguide that is heat-treated in a temperature range of 0 ° C.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view of an example of the silica-based waveguide of the present invention.

The waveguide shown in FIG. 1 includes intermediate layers 3 and 5 embedded on a substrate 1 so as to cover a periphery of a core 4 having a substantially rectangular cross section, and further includes the intermediate layer (core embedded layer). 3,5
SiO ₂ cladding layer 2 embedded so as to cover the periphery of
6, the core 4 is made of a SiO ₂ -based glass or SiOxNyHz-based glass added with a refractive index controlling additive component having a high refractive index (refractive index improving dopant such as GeO ₂ or TiO ₂ ). The intermediate layer is a waveguide made of a fluorine (F) -doped SiO ₂ glass having a low refractive index. When a SiO ₂ glass substrate is used as the substrate 1, the lower cladding layer 2 can be omitted.

FIGS. 2 to 5 are schematic process diagrams (partial views) of an example of a method for manufacturing a quartz-based waveguide according to the present invention.

As shown in FIG. 2, in step (a), an SiO ₂ clad layer 8 is formed on a substrate 7 made of Si.
To form Examples of film forming techniques for forming the SiO ₂ clad layer 8 include a plasma CVD method, a sputtering method, and an ion beam method. Note that, as the substrate 7, Si
When an O ₂ -based glass substrate is used, the formation of the cladding layer 8 in step (a) is omitted, and step (b)
To form an intermediate layer.

In step (b) of FIG. 2, a film 9 for an intermediate layer is formed on the clad layer formed in the previous step. The film 9 is made of a fluorine-added SiO ₂ -based glass having a low refractive index by adding fluorine, and a plasma CVD method is used as a film forming technique for forming the film.
In this case, the silicon (Si) component raw material is Si (Si).
H ₄ , TEOS, etc., and fluorinated hydrocarbons (CF ₄ , C ₂ F _6, etc.) as fluorinated materials are oxidizing gases (O ₂ ).
Is reacted with. When a SiO ₂ glass substrate is used as the substrate 7, the film 9 can be formed on the substrate 7.

In step (c) of FIG. 2, the core film 1 for the core is placed on the film 9 for the intermediate layer formed in the previous step.
0 is formed. The core film 10 has a refractive index improving component (Ge
O ₂ , TiO ₂ etc.) added SiO ₂ glass or S
It is made of iOxNyHz-based glass, and as a film forming technique for forming the same, a plasma CVD method, a sputtering method, an ion beam method, and the like can be given.

In step (d) of FIG. 2, the core film 9
Is performed after the formation of. The heat treatment is performed in a temperature range of 800 ° C. to 1200 ° C. in an oxygen or nitrogen atmosphere.

In step (e) of FIG. 2, a wsi film 11 is formed by a sputtering method on the core film 10 for the core that has been heat-treated in the previous step.

In step (f) of FIG. 3, the wsi film 11 formed in the previous step is processed by a photolithography process and a dry etching process to form a wsi mask pattern 12 for the core 13 on the core film 10. .

In step (g) of FIG. 3, the core film 10 with the wsi mask pattern 12 formed in the previous step (f) is etched by a dry etching process to form the core 13 with the wsi mask pattern 12. .

In step (h) of FIG. 3, the core 13 with the wsi mask pattern 12 formed in the previous step (g) is etched by a dry etching process to remove the wsi mask pattern 12, thereby forming the core 13.

In step (i) of FIG. 4, fluorine-containing SiO ₂ for the intermediate layer is formed so as to cover and embed both side surfaces and the upper surface of the core 13 formed in the previous step (h).
A film 14 made of a system glass is formed. As a film forming technique for forming the film 14, a plasma CVD method may be mentioned. In this case, the silicon (Si) component raw material is Si (Si).
H ₄ , TEOS, etc., and fluorinated hydrocarbons (CF ₄ , C ₂ F _6, etc.) as fluorinated materials are oxidizing gases (O ₂ ).
Is reacted with.

In step (j) of FIG. 4, a wsi film 15 is formed by a sputtering method on the intermediate layer film 14 formed in the previous step (i).

In step (k) of FIG. 4, the wsi film 15 formed in the previous step (j) is processed by a photolithography process and a dry etching process to
A wsi mask pattern 16 for 7 and 18 is formed.

In step (l) of FIG. 5, the films 9 and 14 for the intermediate layer with the wsi mask pattern 16 formed in the previous step (k) are dry-etched in a dry etching process to perform the intermediate layer with the wsi mask pattern. 17,18
Forming

In step (m) of FIG. 5, the wsi mask pattern is removed to form intermediate layers 17 and 18.

In step (n) of FIG.
An intermediate layer 17 in which a core 13 formed by
18 so as to cover and embed both sides and the upper surface of
iO _TwoAn upper clad layer 19 made of a base glass is formed.
You.

In step (o) of FIG. 5, the laminates 7, 8, 13, 17, 18, and 19 with the upper clad layer 19 formed in the previous step (n) (however, the SiO ₂ glass When a substrate is used, the lower clad layer 8 can be omitted) to obtain a waveguide by heat treatment. In this case, the heat treatment condition is 800 ° C. in an oxygen or nitrogen atmosphere.
温度 1200 ° C.

The above steps (a) to (o)
1 having a high refractive index and a substantially rectangular cross section by the step of
3 is embedded so that an intermediate layer having a low refractive index covers it, and the intermediate layers 17 and 18 are further formed of SiO ₂ glass layers (7 and 7).
8, 19 or 7, 19, in which case the substrate 7 is S
An embedded structure is formed so as to cover with an iO ₂ -based glass substrate).

FIG. 6 is a schematic sectional view of another example of the silica-based waveguide of the present invention.

FIG. 7 is a refractive index distribution diagram of the silica-based waveguide of the present invention.

The waveguide shown in FIG.
A silica-based waveguide of the present invention manufactured by the steps (a) to (o), having a refractive index distribution shown in FIG. 7, and details thereof are as follows. Core 2
The dimension 3 is a single mode with a width of 6 μm and a height of 6 μm. The thickness of the intermediate layers 23 and 24 is 2 μm. The thickness of the cladding layers 21 and 25 is 8 μm. Further, the waveguide length is 5
0 μm.

The refractive index was as described below (see FIG. 7). The core 23 was made of SiOxNyHz glass, and the amount of N was set and adjusted so that the relative refractive index difference was + 0.8%. The intermediate layers 22 and 24 are made of fluorine-added SiO ₂
The amount of fluorine was set and adjusted so that the glass was composed of a system glass and the relative refractive index difference was -2.0%. The relative refractive index difference as a whole is 2.8%.

The fluorine concentration in the core 23 is as follows.

The heat treatment after forming the core film 10 for the core is performed at 1200 ° C. for 3 hours at an oxygen flow rate of 2.5 l / min, so that the fluorine concentration in the core film 10 is 2.9.
% Values. The heat treatment after the formation of the upper cladding layer 19 was performed by adjusting the oxygen flow rate to 2.5 l / min.
As a result, the core 1 was treated at 1200 ° C. for 3 hours.
The fluorine concentration in 2 was made to have a value of 5.6%.

FIG. 8 is a loss characteristic diagram of the quartz glass waveguide of the present invention.

The loss characteristics shown in FIG. 8 relate to the quartz glass waveguide of the present invention shown in FIG. 6 and manufactured by the steps described above. Wavelength 1.
The loss at 39 μm was 0.13 dB / cm, and the loss at 1.5 μm was 0.12 dB / cm, which was low throughout.

Table 1 shows comparison results of the loss characteristics between the present invention and the conventional waveguide. The numerical value of the present invention indicates the above case,
Conventional numerical values are described below.

[0051]

[Table 1]

Hereinafter, a conventional silica glass waveguide and a method of manufacturing the same will be described with reference to the drawings for comparison.

FIGS. 9 and 10 are schematic process diagrams (partial views) of a conventional method for manufacturing a silica glass waveguide.

In step (a) of FIG.
SiO ₂ based glass clad layer 27 on top of plasma CVD
It is formed by a film forming technique such as a sputtering method, a sputtering method, and an ion beam method.

In step (b) of FIG. 9, the SiO ₂ -based glass clad layer 27 formed in the previous step (a) is formed.
Addition of refractive index improving component (GeO ₂ , TiO _2, etc.)
The core film 28 for a core having a high refractive index made of iO ₂ -based glass or SiOxNyHz-based glass is formed by plasma CVD.
It is formed by a film forming technique such as a sputtering method, a sputtering method, and an ion beam method.

In step (c) of FIG. 9, the laminate (26, 27, 28) formed in the previous step (b) is subjected to a heat treatment after the formation of the core film. The heat treatment is performed at a temperature of 1200 ° C. or more in an oxygen or nitrogen atmosphere.

In step (d) of FIG. 9, a wsi film is formed by sputtering on the heat-treated core film 28 obtained in the previous step (c).

In step (e) of FIG. 9, the wsi film formed in the previous step (d) is processed by a photolithography process and a dry etching process to form a wsi mask pattern 30 for a core.

In step (e) of FIG. 10, the wsi film formed in the previous step (d) is etched by a dry etching process to remove the wsi mask pattern 30, thereby forming a core 31 having a substantially rectangular cross section. I do.

In step (h) of FIG. 10, an upper clad layer 32 is formed so as to cover both sides and the upper surface of the core 31 formed in the previous step (g).

In step (i) of FIG. 10, the laminate formed in step (h) is heated to a temperature of 1200 ° C. or more in an oxygen or nitrogen atmosphere to obtain a quartz glass waveguide.

FIG. 11 is a schematic sectional view of a conventional silica glass waveguide.

FIG. 12 is a refractive index distribution diagram of a conventional silica glass waveguide.

FIG. 13 is a loss characteristic diagram of a conventional silica glass waveguide.

With reference to FIG. 11, a description will be given of a conventional quartz glass waveguide obtained in the steps (a) to (i) of FIGS. The size of the core 35 is 6 μ in width.
m, 7.5 μm height and single mode. The waveguide length is 50 mm. The core is made of SiOxNghz-based glass, and the relative refractive index difference is set to +0.
8% (see FIG. 12). The heat treatment after forming the core film was performed at 1300 ° C. for 3 hours with a nitrogen flow rate of 2.5 l / min. The heat treatment conditions after the formation of the upper clad layer were an oxygen flow rate of 2.5 l / min, 1250 ° C. for 3 hours.

With reference to FIG. 13, the loss characteristics of the conventional silica glass waveguide obtained above will be described. The loss at a wavelength of 1.39 μm was 0.29 dB / cm, and the loss at a wavelength of 1.5 μm was 0.64 dB / cm. In comparison with the loss in the quartz glass waveguide of the present invention, it is found that the loss is remarkably large at both wavelengths (see Table 1). This is because, since the removal of H in the core is insufficient, the loss is detected as absorption by an OH group at a wavelength of 1.39 μm and absorption by a Si—H or NH group at a wavelength of 1.5 μm. .

As described above, a silica-based glass waveguide having a high relative refractive index difference can be easily obtained by the structure of the present invention and the method of manufacturing the same.

[0068]

The present invention enables a low-loss, high relative refractive index difference silica-based glass waveguide and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of a silica-based glass waveguide of the present invention.

FIG. 2 is a schematic process diagram illustrating an example of a method for manufacturing a silica-based glass waveguide according to the present invention.

FIG. 3 is a schematic process drawing of an example of a method for manufacturing a silica glass waveguide of the present invention.

FIG. 4 is a schematic process drawing of an example of a method for manufacturing a silica glass waveguide according to the present invention.

FIG. 5 is a schematic process drawing of an example of a method for manufacturing a silica glass waveguide of the present invention.

FIG. 6 is a schematic sectional view of another example of the silica-based glass waveguide of the present invention.

FIG. 7 is a refractive index distribution diagram of the silica glass waveguide of the present invention.

FIG. 8 is a loss characteristic diagram of the quartz glass waveguide of the present invention.

FIG. 9 is a schematic process chart of a conventional method for manufacturing a silica glass waveguide.

FIG. 10 is a schematic process chart of a conventional method for manufacturing a silica glass waveguide.

FIG. 11 is a schematic sectional view of a conventional silica glass waveguide.

FIG. 12 is a refractive index distribution diagram of a conventional silica glass waveguide.

FIG. 13 is a loss characteristic diagram of a conventional silica glass waveguide.

[Explanation of symbols]

1,7,20,26,33 substrate 2,6,8,19,21,25,27,32,34,3
6 Cladding layer 3,5,17,18,22,24 Intermediate layer (core burying layer) 4,13,23,31,35 Core 9,14 Intermediate layer film 10,28 Core film 11,15,29 wsi Film 12, 16, 30 wsi mask pattern

Claims (11)

[Claims] 1. A semiconductor device comprising: a substrate; and a structure in which a core made of a high-refractive-index glass having a substantially rectangular cross-section and formed on the substrate is embedded with a core burying layer made of a low-refractive-index glass. In the quartz glass waveguide, the high refractive index glass is made of SiO ₂ glass or Si
OxNyHz-based glass, wherein the low-refractive-index glass is fluorine-added SiO ₂ -based glass, and once or twice by a heat treatment step of heating to a temperature range of 800 ° C. to 1200 ° C. during the manufacturing process of the waveguide. A quartz glass waveguide in which a part of fluorine is diffused and transferred from the core buried layer which is heated and contacts the core. 2. A semiconductor device comprising: a substrate; and a structure in which a core made of high refractive index glass having a substantially rectangular cross section and formed on the substrate is covered with a core burying layer made of low refractive index glass. In the quartz glass waveguide, the high refractive index glass is made of SiO ₂ glass or Si
OxNyHz-based glass, wherein the low-refractive-index glass is fluorine-added SiO ₂ -based glass, and a structure comprising the core and a core burying layer covering the core is further covered with SiO ₂ -based glass. A part of fluorine from the core buried layer, which is heated once or twice or more by a heat treatment step of heating to a temperature range of 800 ° C. to 1200 ° C. during the manufacturing process of the waveguide and the core comes into contact with; A quartz glass waveguide that has been diffused and migrated. 3. A structure including a substrate and a structure in which a core made of a high-refractive index glass having a substantially rectangular cross section and formed on the substrate is covered with a core burying layer made of a low-refractive index glass. In the quartz glass waveguide, the high refractive index glass is made of SiO ₂ glass or Si
An OxNyHz-based glass, wherein the low-refractive-index glass is a fluorine-added SiO ₂ -based glass, and the core and the burying layer covering the core form a structure having a substantially rectangular outer peripheral cross section; Is covered with SiO ₂ glass,
And 800 ° C. to 1200 ° C. during the manufacturing process of the waveguide.
1 or 2 depending on the heat treatment step of heating to the temperature range of
A silica-based glass waveguide in which a part of fluorine is diffused and transferred from the core buried layer, which is heated at least twice and the core is in contact with the core. 4. A structure having a substantially rectangular outer peripheral cross section formed by covering the outer periphery of a core made of high refractive index glass having a substantially rectangular cross section and formed on a substrate with a core burying layer made of low refractive index glass. In a waveguide having a structure in which the outer periphery of an object is covered with a SiO ₂ -based glass layer, the substrate is an SiO ₂ -based glass substrate, and the high-refractive-index glass is made of a material having a refractive index improving component-added Si.
O ₂ -based glass or SiOxNyHz-based glass, wherein the low-refractive-index glass is fluorine-added SiO ₂ -based glass, and the SiO ₂ -based glass layer is formed so as to cover both side surfaces and the upper surface of the substrate and the structure. SiO
Is composed of a ₂ glass layer upper layer, and the waveguide in the manufacturing process of, above it is heated one or more times by a heat treatment step of heating to a temperature range of 800 ° C. to 1200 ° C. and to contact the core A silica glass waveguide in which part of fluorine is diffused and transferred from the core buried layer. 5. A structure having a substantially rectangular outer peripheral cross section formed by covering the outer periphery of a core made of a high refractive index glass having a substantially rectangular cross section and formed on a substrate with a core burying layer made of a low refractive index glass. In a waveguide having a structure in which the outer periphery of an object is covered with a SiO ₂ -based glass layer, the substrate is a Si substrate, and a SiO ₂ -based glass film is formed thereon, and the high refractive index glass improves the refractive index. Component-added SiO ₂ -based glass or SiOxNyHz-based glass, wherein the low-refractive-index glass is fluorine-added SiO ₂ -based glass;
O ₂ -based glass layer is formed on the Si substrate
_{A two} -layer glass film and a SiO ₂ -based glass upper film formed so as to cover both side surfaces and the upper surface of the above-mentioned structure;
A quartz-based glass waveguide that has been heated once or twice or more by a heat treatment step of heating to a temperature range of 0 ° C., and a part of fluorine has been diffused and transferred from the core burying layer with which the core comes into contact. 6. A low-refractive-index glass layer for embedding a core made of fluorine-containing SiO ₂ glass having a substantially rectangular cross section on a substrate and formed of a SiO ₂ -based glass or SiOxNyHz-based glass containing a refractive index improving component. In the method of manufacturing a quartz-based glass waveguide having a structure in which a high-refractive-index glass core is embedded, the low-refractive-index for embedding the core is formed with or without forming an SiO ₂ -based glass layer on the substrate. Forming a lower film for a glass layer, forming a core film for the high refractive index core on the formed lower film, forming the core having a substantially rectangular cross section from the formed core film; An upper film for the core embedding low-refractive-index glass layer is formed so as to cover both side surfaces and the upper surface of the formed core having a substantially rectangular cross-section, and the core is formed on the low-refractive-index glass layer. In the upper and lower membrane A part of fluorine in the low-refractive-index glass for core embedding is diffused and transferred into the high-refractive-index glass core by heat treatment in a temperature range of 800 ° C. to 1200 ° C. after the formation of the core film. A method for manufacturing a quartz glass waveguide. 7. A core-embedded low-refractive-index glass layer made of fluorine-added SiO ₂ glass having a substantially rectangular cross section on a substrate and made of a SiO ₂ -based glass or SiOxNyHz-based glass added with a refractive index improving component. In the method of manufacturing a quartz-based glass waveguide having a structure in which a high-refractive-index glass core is embedded, the low-refractive-index for embedding the core is formed with or without forming an SiO ₂ -based glass layer on the substrate. Forming a lower film for a glass layer, forming a core film for the high refractive index core on the formed lower film, forming the core having a substantially rectangular cross section from the formed core film; An upper film for the core embedding low-refractive-index glass layer is formed so as to cover both side surfaces and the upper surface of the formed core having a substantially rectangular cross-section, and the core is formed on the low-refractive-index glass layer. In the upper and lower membrane An upper film for the SiO ₂ -based glass layer is formed on the formed upper film for the low-refractive-index glass layer for embedding the core, and 800 ° C. to 1200 ° C. after the formation of the core film. A method for producing a quartz glass waveguide in which a part of fluorine in a low-refractive index glass for embedding a core is diffused and transferred into a high-refractive index glass core by heat treatment in a temperature range of ° C. 8. A low refractive index glass layer for embedding a core made of fluorine-containing SiO ₂ glass having a substantially rectangular cross-section on a substrate, and made of SiO ₂ glass or SiOxNyHz glass having a refractive index improving component added. In the method of manufacturing a quartz-based glass waveguide having a structure in which a high-refractive-index glass core is embedded, the low-refractive-index for embedding the core is formed with or without forming an SiO ₂ -based glass layer on the substrate. Forming a lower film for a glass layer, forming a core film for the high refractive index core on the formed lower film, and forming a substantially rectangular cross section from the formed core film and the lower film; Forming a core and a lower part of a low refractive index glass layer for embedding the core having substantially the same width in contact with the lower surface thereof, and forming the core having a substantially rectangular cross section and the lower part of the low refractive index glass layer for embedding the core. Sides of the structure comprising An upper film for the core-embedded low refractive index glass layer covering the upper surface is formed, and the formed structure has a substantially rectangular cross section in which the outer periphery of the core is covered with the core embedded low-refractive index glass layer. A structure is formed, and both sides and an upper surface of the formed structure are covered with the upper film for the SiO ₂ -based glass layer so as to be embedded, and a temperature range of 800 ° C. to 1200 ° C. after the formation of the core film. A method for producing a silica glass waveguide in which a part of fluorine in the low refractive index glass for embedding the core is diffused and transferred into the high refractive index glass core by heat treatment. 9. A low-refractive-index glass layer for embedding a core made of fluorine-containing SiO ₂ glass having a substantially rectangular cross-section on a substrate and made of SiO ₂ -based glass or SiOxNyHz-based glass added with a refractive index improving component. In the method of manufacturing a quartz-based glass waveguide having a structure in which a high-refractive-index glass core is embedded, the low-refractive-index for embedding the core is formed with or without forming an SiO ₂ -based glass layer on the substrate. Forming a lower film for a glass layer, forming a core film for the high refractive index core on the formed lower film, forming the core having a substantially rectangular cross section from the formed core film; An upper film for the core embedding low refractive index glass layer is formed so as to cover both side surfaces and the upper surface of the formed core having a substantially rectangular cross section, and the core is embedded with the embedding low refractive index. Top membrane and bottom for glass layer Part of fluorine in the low-refractive-index glass for core embedding is diffused into the high-refractive-index glass core by performing heat treatment at a temperature in the range of 800 ° C. to 1200 ° C. after the formation of the core film.・ After the transfer and the formation of the upper film for the low refractive index glass layer for embedding the core,
A method for manufacturing a quartz-based glass waveguide which is heat-treated in a temperature range of 0 ° C to 1200 ° C. 10. A low refractive index glass layer for embedding a core made of fluorine-containing SiO ₂ glass having a substantially rectangular cross-section on a substrate, and a refractive index improving component-added SiO ₂ glass or SiOxNyHz glass. In the method of manufacturing a quartz-based glass waveguide having a structure in which a high-refractive-index glass core is embedded, the low-refractive-index for embedding the core is formed with or without forming an SiO ₂ -based glass layer on the substrate. Forming a lower film for a glass layer, forming a core film for the high refractive index core on the formed lower film, forming the core having a substantially rectangular cross section from the formed core film; An upper film for the core embedding low refractive index glass layer is formed so as to cover both side surfaces and the upper surface of the formed core having a substantially rectangular cross section, and the core is embedded with the embedding low refractive index. An upper membrane for the glass layer and An upper film for the SiO ₂ -based glass layer is formed on the formed upper film for the low refractive index glass layer for embedding the core, and after forming the core film, ° C. was heat treated at a temperature in the range of to 1200 ° C. diffusion and to shift to a high refractive index glass core in a portion of the fluorine in the low refractive index glass core embedded in further upper layer for the SiO ₂ based glass layer 800 ° C after formation
A method for manufacturing a quartz-based glass waveguide which is heat-treated in a temperature range of -1200 ° C. 11. A core-embedded low refractive index glass layer made of fluorine-containing SiO ₂ glass having a substantially rectangular cross-section on a substrate and made of SiO ₂ glass or SiOxNyHz glass with a refractive index improving component added. In the method of manufacturing a quartz-based glass waveguide having a structure in which a high-refractive-index glass core is embedded, the low-refractive-index for embedding the core is formed with or without forming an SiO ₂ -based glass layer on the substrate. Forming a lower film for a glass layer, forming a core film for the high refractive index core on the formed lower film, and forming a substantially rectangular cross section from the formed core film and the lower film; A core having a substantially rectangular cross-section formed by forming a core and a lower part of a low refractive index glass layer for embedding the core having substantially the same width in contact with the lower surface thereof, and the low refractive index glass layer for embedding the core below the core; Of the structure consisting of the lower part A substantially rectangular shape in which an upper film for a core-embedded low-refractive-index glass layer covering both side surfaces and an upper surface is formed, and the outer periphery of the core is covered with the core-embedded low-refractive-index glass layer from the formed structure. A structure having a cross section is formed, and both side surfaces and an upper surface of the formed structure are covered and covered with the upper film for the SiO ₂ -based glass layer, and after the formation of the core film, 800 ° C. to 1200 ° C. A part of fluorine in the low-refractive-index glass for embedding the core is diffused and transferred into the high-refractive-index glass core.
800 ° C. to 12 ° C. even after forming the upper film for the O ₂ glass layer.
A method for producing a quartz glass waveguide which is heat-treated in a temperature range of 00 ° C.