JP2001281479A - High-polymer optical waveguide element and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of an optical waveguide element which does not require the self-alignment of an optical waveguide element and an optical fiber as well as a method for easily manufacturing the optical waveguide element. SOLUTION: The high-polymer optical waveguide element has a silicon substrate 1, an optical waveguide part 10 which is formed integrally with the substrate 1 near the central part of the substrate 1, V-groove parts 20 which are formed on both sides of the optical waveguide part 10 so as to hold the optical waveguide part in-between and groove parts 30 which are disposed at the boundary between the optical waveguide part 10 and the V-groove parts 20. The V-groove parts 20 are regions where many V-grooves 20a of a V shape in sectional shape are formed in parallel. These regions are optical fiber packaging parts where the optical fibers are packaged into the respective V-grooves 20a and are self-aligned and fastened to the corresponding cores of the optical waveguide part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer optical waveguide device having an optical fiber mounting portion and a method for easily manufacturing the polymer optical waveguide device.

[0002]

2. Description of the Related Art Conventionally, as an optical waveguide device used for optical communication, optical interconnect, and the like, an optical waveguide device using a silica-based material having a low loss in an infrared wavelength region has been mainly used. BACKGROUND ART Flexible polymer optical waveguides formed using materials have been actively developed.
Quartz-based materials can be formed by flame deposition, CV
The method is performed by the method D or the like, but for this, a large-scale apparatus such as a vacuum film forming apparatus is required, so that it is expensive to manufacture an optical waveguide element. On the other hand, since a thin film of a polymer material can be easily formed by a spin coating method or the like, an optical waveguide device can be formed at low cost.
Various polymer materials are used as the polymer material used for forming the optical waveguide element. Among them, polyimide is particularly high in heat resistance and is used for optical communication by fluorinating 1.3 μm. Since the loss is small even in the wavelength range of 1.55 μm, the material is suitable for forming the optical waveguide.

The manufacturing process of an optical waveguide device using fluorinated polyimide will be described below. First, a fluorinated polyimide having a low refractive index is formed on a silicon substrate as a lower cladding layer, and a fluorinated polyimide having a high refractive index is formed thereon as a core layer. Next, a resist pattern corresponding to the pattern of the core to be formed is formed on the core layer by photolithography using a silicon-containing photoresist, and the resist pattern is used as a mask to form a reactive ion etching apparatus (hereinafter referred to as RIE).
The core pattern is formed by dry-etching the core layer using oxygen plasma by an apparatus. Next, after removing the resist pattern, a fluorinated polyimide having a small refractive index is formed as an upper cladding layer.

As a result, a polymer optical waveguide device in which the lower clad layer, the core, and the upper clad are formed of fluorinated polyimide is completed. The fluorinated polyimide used for the lower cladding layer, the core, and the upper cladding is formed by spin-coating a solution of a fluorinated polyamic acid, which is a precursor of the fluorinated polyimide, on a silicon substrate by spin coating, and baking this to form an imide. To obtain a fluorinated polyimide film. Conventionally, when an optical waveguide device is used for an optical interconnect or the like, a method of bonding the optical waveguide device substrate to a base substrate having a V-groove for introducing a fiber, and bonding the V-groove substrate to an end surface of the optical waveguide device substrate The connection between the optical waveguide element and the optical fiber has been performed by a method or the like.

[0005]

However, when connecting an optical fiber as an optical wiring from the optical waveguide element, a method of bonding the optical waveguide element substrate to the base substrate having the above-described V-groove for fiber introduction formed therein. Even if a method of bonding a V-groove substrate to an end face of an optical waveguide element substrate or the like is used, a process of aligning the core of the optical waveguide element and the core of the optical fiber,
There is a problem that the process of adjusting the position of the substrate is complicated, which causes an increase in cost, and is not suitable for mass production.

The present invention solves the above problems, and provides a structure of an optical waveguide device which does not require alignment when connecting the optical waveguide device to an optical fiber, and a method of easily manufacturing the optical waveguide device. The purpose is to:

[0007]

In order to solve the above-mentioned problems, a polymer optical waveguide device according to the present invention uses a polymer material on a substrate on which a V-groove for mounting an optical fiber is formed. The optical waveguide portion formed by the above process is integrally formed. According to a second aspect of the present invention, in the polymer optical waveguide device according to the first aspect, the optical waveguide portion and the region where the V-groove is formed are arranged adjacent to each other, and a plurality of optical waveguides are arrayed in the optical waveguide portion. The optical waveguide is characterized in that the V-grooves for mounting optical fibers are provided corresponding to the cores of the respective optical waveguides.

In the polymer optical waveguide device according to the first or second aspect, an optical fiber having a size in consideration of the angle of each V-groove and the position of the core of the optical waveguide is selected and mounted on the V-groove. By fixing the optical fiber after it is brought into contact with the end face of the core 13a, the core of the optical waveguide portion and the core of the optical fiber can be connected without adjustment.

According to a third aspect of the present invention, an optical waveguide portion made of a polymer material is formed in a region where an optical waveguide portion is to be formed on a substrate,
In the method for manufacturing a polymer optical waveguide element, a V-groove forming region in which a V-groove for mounting an optical fiber is formed in a region adjacent to the region where the optical waveguide portion is to be formed on the substrate is provided. Providing a V-groove forming region in which a V-groove for mounting an optical fiber is formed in a region adjacent to the region to be formed; applying a soluble thin film on the V-groove forming region; Forming a lower cladding layer using a polymer material on the planned region and the V-groove forming region, forming a core layer using a polymer material on the lower cladding layer, and patterning the core layer. Performing, a step of forming a core pattern at least on an optical waveguide formation scheduled region of the substrate, and a step of forming an upper clad layer using a polymer material on the lower clad layer and the core pattern. A groove is formed at an edge portion of the soluble thin film which is a boundary between the optical waveguide portion forming region and the V-groove forming region, whereby a lower cladding layer and a core pattern are formed in an optical waveguide portion forming region of the substrate. A step of completing an optical waveguide portion comprising an upper cladding layer, dissolving and removing the soluble thin film, and removing each layer made of a polymer material remaining on the V-groove forming region by lift-off accompanying the removal of the soluble thin film. Exposing the V-groove thereby,
It is characterized by having.

According to this method, the optical waveguide portion and the optical fiber mounting portion are integrally formed, and the connection of the optical fiber is
It is only necessary to hit the core of the optical waveguide along the groove, there is no need for complicated alignment, and the height of the center of the optical fiber when it is placed in the V groove is predicted in advance, and the lower clad It is sufficient to control the layer thickness accordingly.

According to a fourth aspect of the present invention, in the method for manufacturing a polymer optical waveguide device according to the third aspect, the formation of the V-groove is performed by:
It is characterized in that it is performed by a dicing saw. Claim 5
According to a third aspect of the present invention, in the method for manufacturing a polymer optical waveguide device according to the third aspect, a silicon substrate is used as the substrate, and the V-groove is formed by anisotropic etching of the silicon substrate. According to the method of claim 4 or 5, a V-groove can be formed satisfactorily. In particular, according to the method of claim 5, the V-groove can be formed more accurately than the method of claim 4.

According to a sixth aspect of the present invention, in the method of manufacturing a polymer optical waveguide device according to any one of the third to fifth aspects, any one of a copper thin film and an aluminum thin film is used as the soluble thin film. It is characterized by the following. According to the method of claim 6, the lift-off step can be performed favorably.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the structure of the polymer optical waveguide device according to the first embodiment of the present invention will be described in detail below with reference to FIG.

As shown in the perspective view of FIG. 1, this polymer optical waveguide device comprises a silicon substrate 1, an optical waveguide portion 10 formed integrally with the substrate 1 near the center of the substrate 1, and an optical waveguide portion. V-shaped groove portions 2 formed on both sides thereof so as to sandwich
0, a groove portion 30 provided at a boundary between the optical waveguide portion 10 and the V groove portion 20 is provided. As shown in FIG. 1, the surface of the silicon substrate 1 is roughly divided into three regions, that is, a region where the optical waveguide portion 10 is formed and regions where two V-groove portions 20 are formed on both sides thereof. The V-groove portion 20 is an optical fiber mounting portion in which a plurality of V-shaped grooves (hereinafter referred to as V-grooves) 20a are formed in parallel, and an optical fiber is mounted in each V-groove 20a.

The optical waveguide section 10 has a plurality of optical waveguides arranged in an array. This optical waveguide section 10
Is a lower clad layer 11 formed of a polymer material such as fluorinated polyimide, and a core 13a formed of a polymer material such as fluorinated polyimide and formed to have a refractive index higher than that of the lower clad layer 11. , A lower clad layer 1 made of a polymer material such as fluorinated polyimide
The upper cladding layer 15 is formed so as to have a refractive index equivalent to that of 1. The core 13a is surrounded by the lower cladding layer 11 and the upper cladding layer 15 except for the end face. In the example shown in FIG. 1, an example in which there are three cores 13a (that is, three optical waveguides) is schematically shown. However, the number of cores 13a, that is, an array of optical waveguides corresponding to the number of cores is shown. Can be appropriately increased or decreased according to the design.

Each V-groove 20 formed in the V-groove 20
a are provided so as to correspond to the predetermined cores 13a, respectively, so that the optical axis of the corresponding core 13a is located on a plane perpendicular to the surface of the substrate 1 including the central axis of each V-groove 20a and an extension thereof. Is formed. In the example of FIG.
The number of V-grooves is three corresponding to the number a (three). The angle of the inclined portion of each V-groove 20a is such that when an optical fiber having a predetermined diameter is mounted in the V-groove 20a, the optical axis of the core of the optical fiber to be mounted and the optical axis of the core 13a of the optical waveguide 10 are set. It is formed to match.

Therefore, the angle of each V-groove 20a and the core 13a
By selecting an optical fiber having a size in consideration of the position and mounting the optical fiber in the V-groove 20a and abutting the end face of the corresponding core 13a, the optical fiber is fixed by using an epoxy resin or the like. The core 13a of the optical waveguide unit 10 and the core (not shown) of the optical fiber can be connected without adjustment.

Next, a manufacturing process of the polymer optical waveguide device according to the first embodiment will be described with reference to FIGS. In the following drawings, the same parts as those in FIG.

First, a step of forming a V groove 20a on the surface of the silicon substrate 1 shown in FIG. 2 is performed. In this step, FIG.
As shown in the plan view of FIG. 1C, for example, a region having a width of 20 mm at the center of a silicon substrate (600 μm thick) 1 made of a 3-inch silicon wafer is a region 1 where an optical waveguide is to be formed
a, and a V-groove forming region 1b having a large number of V-grooves 20a formed on both sides thereof. Each V-groove 20a is 100 μm wide and 50 μm deep using a dicing saw (manufactured by Disco Corporation) equipped with a V-groove blade with a 45 ° inclination angle.
Were formed at intervals of 250 μm. Here, FIG.
FIG. 2A is a partially enlarged cross-sectional view of a part of the V-groove forming region 1b in the silicon substrate 1 along the arrow X direction in FIG. 2C. FIG. 2 (B) is a plan view of a region 1a where an optical waveguide section is to be formed on the silicon substrate 1 in FIG.
3 is a partially enlarged cross-sectional view taken along the arrow X direction of FIG. Although only a part of the V-groove 20a is shown in FIG. 2C, the V-groove 20a is actually formed also in a portion shown by a dotted line T in FIG.
Are arranged in the direction of the arrow X, and the required number is formed according to the design.

Next, the V-groove forming region 1 of the substrate 1 shown in FIG.
The step of forming the copper thin film 41 on b is performed. In this step, first, a copper thin film is deposited on the entire surface of the substrate 1 by sputtering. The thickness was about 200 nm. Then, as shown in the plan view of FIG. 3C, the copper thin film is removed from the copper thin film on the optical waveguide portion forming region 1a at the center of the substrate 1 by ordinary photolithography and etching. The copper thin film 41 is adhered only on the V-groove forming region 1b of the substrate 1 so as to remain. Here, FIG.
FIG. 3A is a partially enlarged cross-sectional view of a part of the V-groove forming region 1 b in the silicon substrate 1 along the arrow X direction in FIG. FIG. 3B shows an area 1a where the optical waveguide portion is to be formed in the silicon substrate 1 in FIG.
3 is a partially enlarged cross-sectional view taken along the arrow X direction of FIG.

Next, as shown in FIG. 4, a step of forming a lower cladding layer is performed. In this step, as shown in the plan view of FIG. 4C, the entire surface of the substrate 1 including the region where the copper thin film 41 is applied on the V-groove forming region 1b is formed of a cladding material by a dipping method. A fluorinated polyimide solution (trade name: OPI-N3205, manufactured by Hitachi Chemical Co., Ltd.) is coated, placed in a predetermined oven, and heated at 370 ° C. for 1 hour in a nitrogen gas atmosphere to perform imidization treatment. The lower cladding layer 11 was formed. This state is shown in FIG.
(A) and (B) are also shown in partial sectional views.

Here, the thickness of the lower cladding layer 11 is V
The optical fiber is placed at the time of forming the groove, the height of the center of the optical fiber from the substrate surface is measured, and a value obtained by subtracting 3.5 μm is obtained.
The optical axis of m) was set so as to coincide with the optical axis of the core (core diameter 10 μm) of the optical fiber mounted in the V groove 5a. In this example, the thickness of the lower cladding layer 11 is about 35 μm.
m.

Here, in order to strengthen the adhesion of the lower cladding layer 11 made of fluorinated polyimide to the substrate 1,
It is preferable to perform a coupler treatment before forming the lower clad layer. In this embodiment, though not shown, the coupler treatment is performed before coating the fluorinated polyimide solution. This coupler treatment is performed by spin-coating a coupler (OPI-Coupler, manufactured by Hitachi Chemical Co., Ltd.) under a nitrogen gas atmosphere.
It is performed by firing at 0 ° C. for 1 hour. FIG. 4A is a partially enlarged cross-sectional view of a part of the V-groove forming region 1b in the silicon substrate 1 along the direction of the arrow X in FIG. 4C. FIG. 4 (B) shows the region 1 where the optical waveguide section is to be formed in the silicon substrate 1 in FIG. 4 (C).
FIG. 3A is a partially enlarged cross-sectional view of a part along the arrow X direction of FIG.

Next, as shown in FIG. 5, a step of forming a core layer is performed. In this step, a fluorinated polyimide solution (trade name: OPI-N3405, manufactured by Hitachi Chemical Co., Ltd.) having a smaller fluorine content than the cladding material is used as a polymer material for the core, and the fluorinated polyimide solution is formed on the entire lower cladding layer 11. The solution is formed into a film by spin coating, and the same baking treatment as that for the lower clad layer is performed.
It was set to 3. The thickness of this core layer was 7 μm. Also,
Since a fluorinated polyimide solution having a smaller fluorine content than the cladding material is used as the polymer material for the core, the optical refractive index of the formed core layer 13 is larger than that of the lower cladding layer 11. It has become something. Here, FIG. 5A is a view corresponding to a cross-sectional position similar to that of FIG. 4A, and the arrow X direction of the V-groove forming region 1b in the silicon substrate 1 (for example, see FIG. 4C). 2 shows a partially enlarged cross-sectional view along a line. FIG. 5 (B)
Is a diagram corresponding to a cross-sectional position similar to that of FIG.
FIG. 4 is a partially enlarged cross-sectional view of a part of an area 1a where an optical waveguide section is to be formed in the silicon substrate 1 taken along the direction of arrow X (see, for example, FIG. 4C).

Next, as shown in FIG. 6, a step of forming a resist layer is performed. In this step, a silicon-containing resist (trade name: RU-1600P, manufactured by Hitachi Chemical Co., Ltd.) was spin-coated on the entire surface of the core layer 13 to form a resist layer 43. Here, FIG. 6A is a view corresponding to the same cross-sectional position as FIG. 5A, and the direction of the arrow X in the V-groove forming region 1b in the silicon substrate 1 (for example, see FIG. 4C). 2 shows a partially enlarged cross-sectional view along a line. FIG. 6 (B)
Is a view corresponding to a cross-sectional position similar to FIG.
FIG. 4 is a partially enlarged cross-sectional view of a part of an area 1a where an optical waveguide section is to be formed in the silicon substrate 1 taken along the direction of arrow X (see, for example, FIG. 4C).

Next, as shown in FIG. 7, a step of forming a resist pattern corresponding to the pattern of the core is performed. In this step, a photomask (not shown) having an opening pattern in which a plurality of openings each having a line width of 10 μm and a length of 20 μm in the region 1a where the optical waveguide portion is to be formed is arranged in parallel at a pitch of 250 μm is used. The opening pattern of this photomask is made to correspond to the core pattern forming position of the optical waveguide portion forming region 1a (for example, see FIG. 4C), and is on the extension of the central axis of each opening pattern having a line width of 10 μm. Then, exposure and development were performed so that the central axes of the corresponding V-grooves overlap each other, and a resist pattern 43a corresponding to a core pattern to be formed later was formed on the optical waveguide portion forming region 1a of the substrate 1. . FIG. 7B shows the state. Further, as shown in FIG. 7A, the resist layer 43 provided on the V-groove forming region 1b is removed by the above-described developing step.

Here, the resist pattern 43a is used.
FIG. 7A shows an example in which the resist pattern 15a is not provided in the V-groove forming region 1b, but it is of course possible to form the resist pattern 15a so as to extend to the V-groove forming region 1b. Here, FIG. 7A is a view corresponding to a cross-sectional position similar to that of FIG. 6A, and the arrow X direction of the V-groove forming region 1b in the silicon substrate 1 (for example, see FIG. 4C). 2 shows a partially enlarged cross-sectional view along a line. FIG. 7B
Is a view corresponding to a cross-sectional position similar to that of FIG.
FIG. 5 is a partially enlarged cross-sectional view of a part of an area 1a where an optical waveguide portion is to be formed in the silicon substrate 1 taken along a direction indicated by an arrow X (for example, see FIG. 4C).

Next, as shown in FIG. 8, a step of forming a core pattern is performed. In this step, ion etching using oxygen plasma was performed using the resist pattern 43a as a mask, and the pattern of the core 13a was formed in a parallel array only on the region 1a where the optical waveguide portion is to be formed on the substrate 1. FIG. 8B shows the state. FIG.
As shown in (A), the core layer 13 provided on the V-groove forming region 1b is removed by the above-described ion etching process. Here, FIG. 8A is a view corresponding to a cross-sectional position similar to FIG.
FIG. 5 is a partially enlarged cross-sectional view of a part of the groove forming region 1b along the arrow X direction (for example, see FIG. 4C). FIG.
7B is a view corresponding to a cross-sectional position similar to that of FIG. 7B, and is along the arrow X direction of the region 1a where the optical waveguide portion is to be formed in the silicon substrate 1 (for example, see FIG. 4C). 2 shows a partially enlarged cross-sectional view.

Next, as shown in FIG. 9, a step of forming an upper clad layer is performed. In this step, first, the core 13a
After removing the resist pattern 43a remaining on the pattern of the lower clad layer 1, the lower clad layer 1 is formed on the pattern of the core 13a formed on the substrate 1 and on the entire surface of the lower clad layer 11.
In the same manner as in the formation step 1, a fluorinated polyimide solution (trade name: OPI-N3205, manufactured by Hitachi Chemical Co., Ltd.), which is the same clad material used for forming the lower clad layer 11, is spin-coated to form the lower clad layer 11 and the core. The same sintering process as that for forming the layer 13 was performed to form the upper clad layer 15. The thickness of the upper clad layer 15 from the surface of the lower clad layer 11 was set to 20 μm. The optical refractive index of the upper cladding layer 15 is similar to that of the lower cladding layer 11.

FIG. 9C is a plan view showing a state in which the upper clad layer 15 is formed. An optical waveguide section 10 including a lower cladding layer 11, a core pattern 13a, and an upper cladding layer 15 is formed in the optical waveguide forming region 1a 'of the substrate 1 in FIG. 9C. That is, as shown in FIG. 9B, an optical waveguide portion 10 including the lower cladding layer 11, the core pattern 13a, and the upper cladding layer 15 is formed in the optical waveguide forming region 1a 'of the substrate 1. This optical waveguide section 10
, Optical waveguides corresponding to the number of cores 13a are arranged in a parallel array. FIG. 9B is a partially enlarged cross-sectional view of a part of the optical waveguide portion forming region 1a ′ in the silicon substrate 1 along the arrow X direction (see FIG. 9C). Also, as shown in FIG. 9A, the V-groove formation region 1
The upper cladding layer 15 is also formed on the portion where the lower cladding layer 11 is formed. Here, FIG. 9A shows the V-groove forming region 1b of the silicon substrate 1 in the direction of arrow X (FIG.
(See (C)).

Next, as shown in FIG. 10, a step of forming a groove at the boundary between the optical waveguide forming region 1a 'and the V-groove forming region 1b and cutting the end of the V-groove forming region is performed.

First, the boundary between the optical waveguide forming region 1a 'and the V-groove forming region 1b indicated by an arrow A in the plan view of FIG. (See FIG. 3 (C).)
The groove 30 was formed using a dicing blade having a width.
The depth of the groove 30 is about 10 μm from the bottom 20ab of the V groove.
I tried to get deeper. Next, the end of the V-groove forming region 1b indicated by arrow B in the plan view of FIG. 10A (for example, 5 mm outside the groove 30) was cut and removed. FIG.
(B) is an enlarged sectional view showing the state after the cutting.

Next, a lift-off step is performed. Here, the substrate obtained in the step of FIG. 10 is concentrated hydrochloric acid (35%)-
By immersing in a (1: 1) mixed solution of water, the copper thin film 41 in the V-groove forming region 1b is dissolved, and the lower clad layer 11 and the upper clad layer 15 deposited on the copper thin film 41 are removed by lift-off. You. Fig. 11 (A)
And an enlarged sectional view of FIG. 11B.

Next, a dicing step is performed. Here, the number of cores 13a corresponding to a predetermined design condition and the number of V-grooves corresponding thereto are set, and the length of the core pattern of the optical waveguide is set along the dicing line indicated by the one-dot chain line C in FIG. By dicing in parallel with the length direction, individual chips were formed. This chipped polymer optical waveguide device is the device shown in FIG. The V-groove forming region of the polymer optical waveguide device becomes an optical fiber mounting portion.

A single-mode optical fiber (having a core diameter of 10 μm) having a diameter of 125 μm is formed along the V-grooves 20 a on both sides of the optical waveguide section 10 of the polymer optical waveguide device thus manufactured.
The cores of m) were respectively installed so as to abut against the end faces of the cores 13a of the optical waveguide 10, and were fixed with an adhesive.

Next, a laser beam having a wavelength of 1.3 μm is introduced from one of the two optical fibers connected to both sides of a predetermined core of the optical waveguide section 10, and the other optical fiber is supplied with optical power. When connected to a meter and the waveguide loss was measured, it was about 1.0 dB.

As described above, according to the optical waveguide device of this embodiment, since the optical waveguide portion and the optical fiber mounting portion are integrally formed, the connection of the optical fiber is performed along the V-groove.
It is only necessary to hit the core of the optical waveguide section, and there is no need for complicated alignment. In this case, it is sufficient to predict the height of the center of the optical fiber when the optical fiber is placed in the V-groove in advance, and to control the thickness of the lower cladding layer in accordance with it.

Here, 250 μm was used as a test sample.
Although an example of manufacturing an optical waveguide array element having m pitches of parallel lines has been described, the number of dimensions is not limited to this, and the circuit of the element is arbitrarily designed.

In the above description, the case where the copper thin film 41 is used as the dissolvable thin film has been described. However, a case where an aluminum vacuum deposited thin film is used instead of the copper thin film was also examined. When this aluminum thin film was used, the dissolution and peeling in the lift-off step described with reference to FIG. 11 was performed by immersion in phosphoric acid-water (1: 1). In other respects, the production of the optical waveguide element and the connection of the optical fiber were performed in exactly the same manner as in the above-described steps, and the same measurement as described above was performed. In this case, the loss was about 1 dB, which was good. there were.

Next, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment only in the method of forming the V-groove. Here, a silicon substrate (100 plane orientation; hereinafter, 100
An example in which a V groove is formed by anisotropic etching will be described.

First, as shown in FIG. 13A, a predetermined resist is applied to the entire surface of a silicon substrate (100 surface) 1 made of a 3-inch silicon wafer (100 surface) by spin coating. After that, by performing photolithography (exposure, development, etc.) using a predetermined mask, on both sides of an optical waveguide portion forming region 1a having a width of 20 mm at the center of the substrate 1 (see FIG. 2C), A resist pattern 50 in which a large number of lines having a width of 115 μm and a pitch of 250 μm were formed was formed. In FIG. 13A, only a part of a linear opening defined by the resist pattern 50 (corresponding to a V-groove part to be formed later) is shown, but a part shown by a dotted line. Actually, linear openings are formed, and a required number of these linear openings are arranged in the direction of the arrow X. FIG.
(B) Substrate 1 on which linear openings 60 are juxtaposed
FIG.

Next, a KOH aqueous solution (KO) is applied to the silicon substrate (100 surface) 1 on which the resist pattern 50 is formed.
H500 g, water 1000 ml) and anisotropic etching by wet etching at 80 ° C.
As shown in FIG.
V-grooves 20a having a thickness of 18 μm and a depth of 87 μm were formed at a pitch of 250 μm.

Next, as shown in the partial sectional view of FIG. 15B, the resist pattern 50 is removed. This allows
As shown in the plan view of FIG. 15A, for example, a silicon substrate (100 surfaces) 1 made of a 3-inch silicon wafer
A V-groove forming region 1b having a large number of V-grooves 20a was formed on both sides thereof, leaving a region having a width of 20 mm at the central portion as the optical waveguide portion forming planned region 1a. Note that FIG.
Although only a part of the V-groove 20a is shown in the plan view of FIG. 15A, the V-groove 20a is actually formed in a portion indicated by a dotted line T in FIG.
a are arranged in the direction of the arrow X, and a required number according to the design is formed. Here, FIG.
1A, a V-groove formation region 1 in a silicon substrate 1 is formed.
FIG. 3B is a partial enlarged cross-sectional view taken along the arrow X direction of FIG.
An outer diameter of 125 μm is formed on the V groove 20a thus formed.
m, an optical fiber having a core diameter of 10 μm was placed, and the height from the surface of the substrate to the center of the core of the optical fiber was measured to be about 25 μm.

As described above, the steps after providing the V-groove forming region 1b in which a large number of V-grooves 20a are formed on the silicon substrate 1 are the same as the manufacturing steps in the first embodiment. . That is, following the above-described V-groove formation step, a step of forming a copper thin film 41 on the V-groove formation region 1b of the substrate 1 (see FIG. 3), a step of forming the lower cladding layer 11 (see FIG. 4), and a core layer 13, a step of forming a resist layer 43 (see FIG. 6), and a step of forming a resist pattern 43a corresponding to the pattern of the core 13a (FIG. 7).
), A step of forming a pattern of the core 13a (both in width and thickness of 7 μm) (see FIG. 8), a step of forming the upper cladding layer 15 (see FIG. 9), and a process of forming the optical waveguide forming region 1a 'and the V-groove forming region 1b. Formation of groove 30 at boundary and V-groove formation region 1
Steps of cutting the end of b (see FIG. 10), lift-off step (see FIG. 11), and dicing step (see FIG. 12) are sequentially performed to form the copper thin film 41 and the thin film for the optical waveguide. (However, in this case, the lower cladding layer 11
Was formed so as to have a thickness of 21.5 μm), an optical waveguide portion was formed, and then a fluorinated polyimide film on the V-groove forming region was removed together with a copper thin film by lift-off, and a chip was formed by dicing. In this manner, a chip-formed polymer optical waveguide device with an optical fiber mounting portion is completed.

A single-mode optical fiber (having a core diameter of 10 μm) having a diameter of 125 μm was formed along the V-grooves 20 a on both sides of the optical waveguide section 10 of the polymer optical waveguide device thus manufactured.
The cores of m) were respectively installed so as to abut against the end faces of the cores 13a of the optical waveguide 10, and were fixed with an adhesive.

Next, a laser beam having a wavelength of 1.3 μm is introduced from one of two optical fibers connected to both sides of a predetermined core of the optical waveguide section 10, and the other optical fiber is supplied with optical power. When connected to a meter and the waveguide loss was measured, it showed good characteristics of about 1.0 dB.

As described above, also in the optical waveguide device of the second embodiment, since the optical waveguide portion and the optical fiber mounting portion are integrally formed, the connection of the optical fiber is performed along the V groove. It only needs to hit the core of the optical waveguide,
There is no need for complicated alignment. In this case, it is sufficient to predict the height of the center of the optical fiber when the optical fiber is placed in the V-groove in advance, and to control the thickness of the lower cladding layer in accordance with it.

In the second embodiment, the steps of photolithography and etching are included in the processing of the V-groove. However, since the anisotropic etching of the silicon substrate is used, the dicing saw of the first embodiment can be used. The processing accuracy of the V-groove is further improved as compared with the case where it is used, and the alignment between the optical fiber and the optical waveguide can be performed with higher accuracy.

Here, 250 μm was used as a test sample.
An example of fabricating an optical waveguide array element having m-pitch parallel lines has been described, but the dimensions, number, etc., are not limited thereto, and the circuit of the optical waveguide portion of the element is arbitrarily designed. It is. The polymer optical waveguide device of the present invention can be easily connected to an optical fiber without a troublesome alignment step when used for optical coupling or optical branching for optical communication, optical interconnect, and the like. Can be.
Although an optical waveguide array is shown here as an example, a Y-branch, a directional coupler, an optical switch, and the like can be formed in a circuit portion. Furthermore, it is also suitable for mass production.

[0050]

As described in detail above, according to the polymer optical waveguide device of the present invention, the V-groove is formed on the substrate.
Because the polymer optical waveguide part is directly formed integrally,
An optical fiber having a size considering the angle of the V-groove and the position of the core of the optical waveguide is preliminarily selected, mounted on the V-groove and brought into contact with the end face of the corresponding core, and then the optical fiber is fixed. Thereby, the core of the optical waveguide and the core of the optical fiber can be connected without any adjustment.

In the method of manufacturing a polymer optical waveguide device according to the present invention, a fiber mounting portion having a V-groove formed on a substrate is covered with a soluble thin film such as a copper thin film or an aluminum thin film. An optical waveguide section is formed using a molecular material, and then, the soluble thin film is dissolved by a lift-off method, and the polymer material thin film on the soluble thin film is removed, so that the fiber mounting portion including the V-groove is exposed. ing.
According to this method, the optical waveguide portion and the optical fiber mounting portion are integrally formed, and the connection of the optical fiber is performed along the V-groove.
It is only necessary to abut against the core of the optical waveguide part, there is no need for complicated alignment, and the height of the center of the optical fiber when it is placed in the V groove is predicted in advance, and the thickness of the lower cladding layer is adjusted. It is enough to control it accordingly. Therefore, an optical waveguide element that can easily connect to an optical fiber can be easily manufactured without requiring a troublesome alignment process, which is advantageous for mass production.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a structure of a polymer optical waveguide device according to a first embodiment of the present invention.

FIG. 2 is a view for explaining a V-groove forming step on a silicon substrate surface according to the first embodiment of the present invention.

FIG. 3 is a view for explaining a step of forming a copper thin film on a V-groove formation region of a substrate according to the first embodiment of the present invention.

FIG. 4 is a view for explaining a step of forming a lower cladding layer according to the first embodiment of the present invention.

FIG. 5 is a view illustrating a step of forming a core layer according to the first embodiment of the present invention.

FIG. 6 is a view illustrating a step of forming a resist layer according to the first embodiment of the present invention.

FIG. 7 is a view illustrating a step of forming a resist pattern corresponding to a core pattern according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a step of forming a core pattern according to the first embodiment of the present invention.

FIG. 9 is a view for explaining a step of forming an upper cladding layer according to the first embodiment of the present invention.

FIG. 10 is a diagram for explaining a step of forming a groove at a boundary between the optical waveguide forming region and the V groove forming region and cutting an end of the V groove forming region according to the first embodiment of the present invention. It is.

FIG. 11 is a view for explaining a lift-off step according to the first embodiment of the present invention.

FIG. 12 is a view for explaining a dicing step according to the first embodiment of the present invention.

FIG. 13 is a view illustrating a step of forming a resist pattern for forming a V-groove according to a second embodiment of the present invention.

FIG. 14 is a view for explaining an anisotropic etching step for forming a V-groove according to a second embodiment of the present invention.

FIG. 15 is a view for explaining a V-groove forming step according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon substrate 10 Optical waveguide part 11 Lower clad layer 13 Core layer 13a Core 15 Upper clad layer 20 V groove part 20a V groove 30 groove 41 Copper thin film 43 Resist layer 43a Resist pattern 50 Resist pattern

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H037 AA01 BA24 CA34 DA04 DA06 DA12 2H047 KA04 MA05 PA01 PA24 PA28 QA02 QA05 QA07 TA43

Claims (6)

[Claims] 1. A polymer optical waveguide device, wherein an optical waveguide portion formed using a polymer material is integrally formed on a substrate on which a V-groove for mounting an optical fiber is formed. 2. The optical waveguide portion and a region where the V-groove is formed are arranged adjacent to each other, and a plurality of optical waveguides are arranged in an array in the optical waveguide portion, and correspond to a core of each optical waveguide. 2. The polymer optical waveguide device according to claim 1, wherein said V-groove for mounting an optical fiber is provided. 3. An optical waveguide portion made of a polymer material is formed in a region where an optical waveguide portion is to be formed on a substrate, and a V for optical fiber mounting is formed in a region adjacent to the region where the optical waveguide portion is to be formed on the substrate. In a method of manufacturing a polymer optical waveguide device having a V-groove forming region in which a groove is formed, a V-groove forming region in which a V-groove for mounting an optical fiber is formed in a region adjacent to a region where the optical waveguide portion is to be formed on a substrate. Providing a dissolvable thin film on the V-groove forming region; and forming a lower cladding layer using a polymer material on the optical waveguide portion forming region and the V-groove forming region. Forming a core layer using a polymer material on the lower cladding layer, patterning the core layer, forming a core pattern at least on an optical waveguide formation scheduled region of the substrate, beneath Forming an upper clad layer on the lad layer and the pattern of the core using a polymer material; and an edge portion of the dissolvable thin film which is a boundary between the region where the optical waveguide portion is to be formed and the V groove forming region. Forming a groove in the substrate, thereby completing an optical waveguide section comprising a lower clad layer, a core pattern, and an upper clad layer in an area where an optical waveguide section is to be formed on the substrate; and dissolving and removing the soluble thin film. Removing each layer of the polymer material remaining on the V-groove formation region by lift-off accompanying the removal of the conductive thin film, thereby exposing the V-groove. Production method. 4. The method for manufacturing a polymer optical waveguide device according to claim 3, wherein the V-groove is formed by a dicing saw. 5. The method according to claim 3, wherein a silicon substrate is used as the substrate, and the V-groove is formed by anisotropic etching of the silicon substrate. 6. The method for manufacturing a polymer optical waveguide device according to claim 3, wherein one of a copper thin film and an aluminum thin film is used as the soluble thin film.