JPH08122564A - Optical fiber holding substrate and joined body of the optical fiber holding substrate and optical integrated circuit substrate - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] The formed optical circuit does not impede the propagation of light as much as possible, and the connection loss at the connection between the optical fiber and the optical waveguide is possible. Provided is a holding substrate which does not increase substantially. A p-type impurity high-concentration diffusion layer 2 and a second silicon single-crystal layer are formed on a first silicon single crystal 52, and an optical fiber is mounted on the p-type impurity high-concentration diffusion layer. The substrate 1 which has a groove 51 and is formed so that the side portion of the groove is parallel to the surface of the second silicon single crystal layer, or the silicon oxide layer and the second silicon oxide layer on the first silicon single crystal. A silicon single crystal layer is formed, and a groove for mounting an optical fiber is formed on the first silicon single crystal, and a side portion of the groove is composed of the silicon oxide layer and the second silicon single crystal layer. In the substrate formed such that the side portions of the groove are parallel to the surface of the second silicon single crystal layer, the depth of the groove is larger than the radius of the optical fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a substrate for fixing and holding an optical fiber and a joined body of the substrate and an optical integrated circuit substrate having an optical waveguide formed thereon.

[0002]

2. Description of the Related Art Generally, an optical multicore connector is used to connect an end face of an optical fiber to an end face of an optical waveguide formed in an optical integrated circuit such as an integrated optical switch and an integrated optical coupler. The main body of the optical multicore connector is a substrate that holds and holds the optical fiber.

Conventionally, this optical fiber holding substrate has (1)
A p-type impurity high-concentration diffusion layer is formed on the first silicon single crystal, and a second silicon single-crystal layer is formed on the p-type impurity high-concentration diffusion layer, and the p-type impurity high-concentration diffusion layer is formed on the p-type impurity high-concentration diffusion layer. It has a groove for mounting an optical fiber, and the side part of the groove is formed so as to be parallel to the (111) plane of the second silicon single crystal layer, or (2) on the first silicon single crystal A silicon oxide layer and a second silicon single crystal layer formed on the silicon oxide layer, and a groove for mounting an optical fiber is formed on the first silicon single crystal. Layer and the second silicon single crystal layer, and the side portions of the groove are formed so as to be parallel to the (111) plane of the second silicon single crystal layer.

These will be described below according to their manufacturing method. FIGS. 3A to 3F are cross-sectional views schematically showing a process of manufacturing an optical fiber holding substrate having the groove having a rectangular cross-sectional shape as an example of the optical fiber holding substrate of the above (1).
First, a first silicon single crystal substrate 1 is prepared, and a p-type impurity high-concentration diffusion layer 2 is formed as an etching stopper layer on the surface of the substrate 1 (FIG. 3A). Next, as a layer to be etched, a high concentration of p-type impurities is not added, that is, a non-doped, n-type or low-concentration p-type second layer is added.
Epitaxially grow the silicon single crystal 3 of
(B)). Next, the surface of the second silicon single crystal 3 is oxidized to form a silicon oxide layer 4 (FIG. 3 (c)).
Then, since the opening is provided in the silicon oxide layer 4,
With the photolithography technology, the second direction
A photoresist pattern 6 of a groove 5 parallel to the (111) plane of the silicon single crystal 3 was formed (FIG. 3C).
Then, using this photoresist pattern 6 as a mask, H
Etching is performed using a hydrogen fluoride-based aqueous solution such as F—HFN ₄ —H ₂ O (FIG. 3D). Further, the second silicon single crystal 3 is etched through this opening with an anisotropic etching solution such as an aqueous potassium hydroxide solution (FIG. 3 (e)). In the anisotropic etching, while the etching progresses in the depth direction of the groove 5, the (111) plane which is the side surface of the groove 5 is also slightly etched,
The silicon oxide film 4 overhangs in an eaves-like shape on the upper end of the formed groove 5 (FIG. 3E). Therefore, following the anisotropic etching, the silicon oxide film 4 is removed by the hydrogen fluoride based aqueous solution (FIG. 3 (f)).

The holding substrate thus manufactured has a high concentration diffusion layer of p-type impurities on the first silicon single crystal and a second silicon single crystal layer on the high concentration diffusion layer of p-type impurities. A groove for mounting an optical fiber is formed on the high-concentration p-type impurity diffusion layer, and the side portion of the groove is formed so as to be parallel to the (111) plane of the second silicon single crystal layer. To be done.

4 (a) to 4 (f) respectively show the above (2).
FIG. 6 is a cross-sectional view schematically showing a process of manufacturing an optical fiber holding substrate having a groove having a rectangular cross section, using a silicon oxide layer as an etching stopper layer. When a silicon oxide layer is formed as the etching stop layer, the first silicon single crystal substrate 23 and the second silicon single crystal substrate 24, which have their surfaces oxidized in advance to form the silicon oxide layers 21 and 22, are bonded. Then, the silicon oxide layers 21 and 22 are fused at the bonding portion to form the silicon oxide layer 25 (FIG. 4A), and then the second
After polishing and etching the silicon single crystal substrate 24 of FIG. 4 (FIG. 4B), the second silicon single crystal 24 is formed.
Is oxidized to form a silicon oxide layer 26 (see FIG. 4).
(C)). Subsequent to this step, the step of forming the photoresist pattern described above is connected. That is, in order to provide an opening in the silicon oxide layer 26, the longitudinal direction of the second silicon single crystal 2 is determined by photolithography.
After forming the photoresist pattern 28 of the groove 27 parallel to the (111) plane of FIG. 4 (FIG. 4C), using this photoresist pattern 28 as a mask, HF-HFN ₄
Etching is performed using a hydrogen fluoride-based aqueous solution such as —H ₂ O (FIG. 4D). Furthermore, through this opening,
The second silicon single crystal 24 is etched with an anisotropic etching solution (FIG. 4 (e)). Also in this case, the anisotropic etching solution does not etch the silicon oxide layer 25, so that the anisotropic etching stops at the silicon oxide layer 25. Following this anisotropic etching, the silicon oxide films 25 and 26 are removed with the hydrogen fluoride-based aqueous solution (FIG. 4F).

In the holding substrate manufactured by this method, a silicon oxide layer is formed on the first silicon single crystal, and a second silicon single crystal layer is formed on the silicon oxide layer. Has a groove for mounting an optical fiber, the side portion of the groove is constituted by the silicon oxide layer and the second silicon single crystal layer, and the side portion of the groove is the second silicon single crystal layer. It is formed so as to be parallel to the (111) plane. From the optical fiber holding substrate manufactured by these methods, the assembling method previously disclosed by the present inventor (Japanese Patent Application No. 5-35109).
Thus, an optical multicore connector is obtained, and the optical multicore connector and the optical integrated circuit board having the optical waveguide are joined.

FIG. 5 is a schematic exploded perspective view showing a procedure of (1) joining the optical fiber holding substrate and the optical integrated circuit substrate. That is, the optical fiber holding substrate is cut into a substrate 7, the optical fibers 8 are arranged in each groove 5 of the substrate 7, and then fixed by a pressing plate 9 to obtain an optical multicore connector 10. The width of the groove 5 is wider than the diameter of the optical fiber 8. The amount is about ± 1 μm, and the optical fibers 8 can be easily arranged in the groove 5. The arranged optical fibers 8 are fixed and held by pressing the optical fibers 8 against one side wall of the groove 5 by the pressing plate 9. Figure 6
FIG. 3 is a schematic cross-sectional view of the obtained optical multicore connector 10.

Next, in order to join the optical multi-core connector 10 and the optical integrated circuit board 31 having the optical waveguide 30, the optical waveguide 8 is superposed so that the end face of the optical waveguide 30 abuts on the core of the optical fiber 8. After that, the optical axes of the end face of the optical fiber 8 and the end face of the optical waveguide 30 are aligned. In the superposition, as shown in FIG. 5, the optical integrated circuit board 31 in which the optical waveguide 30 is embedded under the surface is placed face down on the surface of the optical multicore connector 10 in which the core portion of the optical fiber 8 projects from the surface. It is done by doing. Further, the alignment of the optical axes of the optical fiber 8 and the optical waveguide 30 in the horizontal direction is performed by aligning predetermined alignment marks (11 and 32, respectively) on both substrate surfaces of the optical fiber holding substrate 7 and the optical integrated circuit substrate 31. It is done by adjusting to the street. FIG. 7 is a schematic perspective view showing a joined state of the optical multicore connector 10 and the optical integrated circuit board 31 after the optical axis alignment.

However, when an optical circuit is formed by producing a holding substrate as described above, fixing and holding an optical fiber, and further producing a joined body of an optical multicore connector and an optical integrated circuit, the optical circuit is formed. In the circuit, the propagation of light is hindered and the connection loss at the connection between the optical fiber and the optical waveguide increases. For such problems,
Conventionally, various proposals have been made, but still severe demands have been made.

[0011]

Therefore, in view of the above circumstances, the object of the present invention is to prevent the formed optical circuit from obstructing the propagation of light as much as possible, and to provide the optical fiber and the optical waveguide. An object of the present invention is to provide an optical fiber holding substrate and a bonded body of the optical fiber holding substrate and the optical integrated circuit substrate, in which the connection loss at the connection portion is not increased as much as possible.

[0012]

The present invention is to achieve the above object, and the first optical fiber holding substrate is
A p-type impurity high-concentration diffusion layer is formed on the first silicon single crystal, and a second silicon single-crystal layer is formed on the p-type impurity high-concentration diffusion layer, and the p-type impurity high-concentration diffusion layer is formed on the p-type impurity high-concentration diffusion layer. In a substrate having a groove for mounting an optical fiber, the side portion of the groove being parallel to the (111) plane of the second silicon single crystal layer, the depth of the groove is the optical fiber. The second optical fiber holding substrate has a silicon oxide layer formed on the first silicon single crystal and a second silicon single crystal layer formed on the silicon oxide layer. 1 has a groove for mounting an optical fiber on the silicon single crystal, the side portion of the groove is constituted by the silicon oxide layer and the second silicon single crystal layer, and the side portion of the groove is the second portion. In the substrate formed to be parallel to the (111) plane of the silicon single crystal layer of The depth of the groove being greater than the radius of the optical fiber.

Further, the bonded body of the optical fiber holding substrate and the optical integrated circuit substrate of the present invention comprises the optical axis of the optical fiber fixedly held on the optical fiber holding substrate and the optical waveguide formed on the optical integrated circuit substrate. In a joined body of the two substrates whose optical axes are aligned with each other, the optical fiber holding substrate and the optical integrated circuit substrate are arranged so that the surfaces of the both substrates share the same plane. Are joined at their end cross-sections.

[0014]

The optical fiber holding substrate of the present invention is the above-mentioned conventional holding substrate, that is, (1) a high concentration diffusion layer of p-type impurities and a high concentration diffusion layer of p-type impurities on the first silicon single crystal. A second silicon single crystal layer is formed on the second silicon single crystal layer, and a groove for mounting an optical fiber is provided on the high concentration diffusion layer of the p-type impurity. ) The substrate formed to be parallel to the plane, or (2) forming a silicon oxide layer on the first silicon single crystal and a second silicon single crystal layer on the silicon oxide layer, and Having a groove for mounting an optical fiber on the silicon single crystal, the side portion of the groove is constituted by the silicon oxide layer and the second silicon single crystal layer, and the side portion of the groove is the second side. In the substrate formed so as to be parallel to the (111) plane of the silicon single crystal layer, the depth of the groove is It is larger than the radius of the optical fiber.

The reason why the above-mentioned object of the present invention can be achieved by setting such a groove depth is presumed to be as follows. That is, in the conventional substrate (1), the silicon single crystal 3 forming the groove 5 forms the upper end and the top 5a of the side of the groove 5, and the upper end and the top 5a of this side form the optical fiber 8. Are in contact. Further, in this state, the contact is a linear or point-like contact with a remarkably small contact area, so that the contact pressure is extremely high.

However, the silicon single crystal 3 is likely to be chipped due to cleavage. Therefore, when the optical fiber 8 is mounted on the substrate 7 or when the optical fiber 8 is mounted on the substrate 7, the upper end and the top portion 5a collide with the end face of the optical fiber 8 or the contact pressure exceeds the pressure resistance strength. It causes a chip. This also applies to the conventional substrate (2). When this chipping occurs, the horizontal position where the optical fiber is fixed, that is, the optical axis position of the optical fiber shifts, and the connection loss at the connecting portion between the optical fiber and the optical waveguide increases. Moreover, the silicon single crystal fragments produced by this chip impede the propagation of light when they penetrate the optical axis between the optical fiber and the optical waveguide, and further intervene in other places between the optical fiber and the optical waveguide. Then, since the close contact between the optical fiber and the optical waveguide is hindered, the connection loss at the connecting portion between the optical fiber and the optical waveguide increases.

FIG. 1 is a schematic sectional view of an optical multicore connector in which an optical fiber is mounted on a first optical fiber holding substrate of the present invention. The optical fiber holding substrate 12 of the present invention has the groove 5
Since the depth of 1 is larger than the radius of the optical fiber 8, the silicon single crystal 52 is not in contact with the optical fiber 8 at the upper end of the side portion of the groove 51 and the top portion 51a.
Therefore, when the optical fiber 8 is mounted on the holding substrate 12, by introducing the optical fiber 8 while crawling to the bottom of the groove 51 of the substrate 12, there is no contact when the optical fiber 8 is mounted on the holding substrate 12. Due to the planar contact with the contact area remarkably increased, the chance that the silicon single crystal 52 is chipped due to the cleavage is significantly reduced. On the other hand, in the conventional optical fiber holding substrate 7, the depth of the groove 5 is set to be equal to or less than the radius of the optical fiber 8 as shown in FIG.

Next, since the bonded body of the optical fiber holding substrate and the optical integrated circuit substrate of the present invention uses the optical fiber holding substrate of the present invention, the formed optical circuit impedes the propagation of light. In addition, the connection loss at the connection between the optical fiber and the optical waveguide does not increase. In addition, as compared with the conventional bonded body of the optical fiber holding substrate and the optical integrated circuit board, vertical and horizontal optical axis alignment between the optical waveguide and the optical fiber and bonding of the circuit board and the holding substrate are performed. Can be performed extremely simply and accurately. In the joined body of the optical fiber holding substrate and the optical integrated circuit substrate of the present invention, the optical axis of the optical fiber fixedly held on the optical fiber holding substrate and the optical axis of the optical waveguide formed on the optical integrated circuit substrate are the same. In the joined body of both the substrates, the optical fiber holding substrate of the present invention and the optical integrated circuit substrate are arranged so that the surfaces of the both substrates share the same plane. It is characterized in that it is joined at the end cross section. When manufacturing the above joined body satisfying this condition, the optical axis alignment between the optical waveguide and the optical fiber in the vertical direction and the horizontal direction is performed as follows.

In the optical axis alignment of the optical waveguide and the optical fiber in the vertical direction, the distance from the plane to be shared to the optical axis of the optical fiber and the distance from the plane to the optical waveguide are equalized. This is established by joining the holding substrate and the optical integrated circuit substrate at their end cross sections so that the surfaces of the both substrates share the same plane. In order for the surfaces of the both substrates to share the same plane, it is preferable to provide a transparent guide plate extending over the both surfaces.

FIG. 8 and FIG. 9 are schematic exploded perspective views showing an example of a procedure for aligning the optical axis in the vertical direction using a guide plate. That is, first, the guide plates 13 and 14 are prepared, some of them are adhered to the same plane 15a of the optical fiber holding substrate 12, and the other parts of the guide plates 13 and 14 are projected. Next, while the same flat surface 15b of the optical integrated circuit board 33 is brought into close contact with the other part of the guide plates 13 and 14, the end sections 16 and 17 of both boards 12 and 33 are brought into close contact with each other. Just do it. In order to confirm the close contact between the guide plates 13 and 14 and the substrates 12 and 33, the interference fringes generated by irradiating the surfaces of the transparent guide plates 13 and 14 with monochromatic light are observed. The close contact between the guide plate and the substrate may satisfy both (1) both contact at one point and (2) both are parallel. With regard to (1), the interference fringes move when the guide plate and the substrate are brought close to each other, but when the two come into contact with each other, the movement of the interference fringes stops. Regarding (2), if the tilting positional relationship between the guide plate and the substrate is adjusted so that the distance between the interference fringes becomes large, the two can be arranged in parallel.

Next, the optical axis alignment of the optical waveguide 34 and the optical fiber 8 in the horizontal direction is performed by preliminarily aligning the optical fiber holding substrate 12 and the optical integrated circuit substrate 33 on both substrate surfaces or on the guide plate. It is established by joining using the mark. When the alignment marks are formed on both substrate surfaces, it is preferable that the alignment marks reach the respective end cross sections. 8 and 9, the alignment mark 35 on the surface of the optical fiber holding substrate 12 and the alignment mark 36 on the surface of the optical integrated circuit substrate 33 reach the end cross sections (16 and 17 respectively) of each substrate. Has been formed. Then, the positional relationship between both substrates is adjusted so that the alignment marks 35 and 36 formed on both substrates match each other as desired.
Further, when the alignment mark is formed on the guide plate, while observing through the guide plate so that the alignment mark formed on the guide plate and the alignment mark formed on the corresponding substrate match in a predetermined manner. Adjust.

[0022]

【Example】

[Example 1] The optical fiber holding substrate shown in Fig. 1 was manufactured through the processes of Figs. 3 (a) to 3 (f). However, since the depths of the grooves are different, the groove 51 corresponds to the groove 5 in FIG. First, a first silicon single crystal substrate 1 having a plate orientation of (110) is prepared, and a high concentration of boron is diffused on the surface of the substrate 1 to a depth of 3 μm and a dopant concentration of 1 on the surface.
A high-concentration p-type impurity diffusion layer 2 of 020 cm −3 was formed (FIG. 3A). The dopant concentration was measured by secondary ion spectroscopy (SIMS). Next, a second silicon single crystal layer 3 having a thickness of 57 μm was epitaxially grown as a layer to be etched (FIG. 3).
(B)). The surface of the second silicon single crystal layer 3 was thermally oxidized to form a silicon oxide layer 4 having a thickness of 0.2 μm (FIG. 3C). Then, after applying the photoresist 6 to the silicon oxide layer 4, three windows having a width of 124 μm and a length of 30 mm were formed every 250 μm by exposure and development (FIG. 3C). Then, using this photoresist pattern 6 as a mask, HF: HFN ₄ : H ₂ O = 1: 1
The silicon oxide layer 4 was removed with an aqueous solution of hydrofluoric acid having a composition of 5: 5 (FIG. 3D). Further, the second silicon single crystal layer 3 was removed through this opening with a 50 wt% KOH aqueous solution at 60 ° C. (FIG. 3E). Following this anisotropic etching, the silicon oxide layer 4 was removed with the hydrofluoric acid aqueous solution (FIG. 3 (f)). The groove 51 thus manufactured has a depth of 67.5 μm, a width of 127 μm,
The length was 30 mm. Finally, the alignment mark was formed as follows. That is, 1 mm from both sides from the center position of the optical fiber mounted in the central groove 51 (62.5 μm position from the side of the groove where the optical fiber is pressure-contacted to the inside of the groove).
A linear pattern 35 having one side at two places was formed by depositing metallic chromium and lifting off.

An optical multicore connector was obtained from the optical fiber holding substrate manufactured in this manner, and the optical multicore connector and the optical integrated circuit board having the optical waveguide were joined as shown in FIGS. 8 and 9. That is, the holding substrate has a width of 5 mm and a length of 2
The substrate 12 is cut into 5 mm and each groove 51 of the substrate 12 is cut.
After arranging the optical fibers 8 (diameter: 120 μm) on the optical fiber, the spring and the pressing plate 9 were fixed from above to obtain an optical multicore connector 37. At this time, no mechanical damage was observed due to the contact between each groove 51 and the optical fiber 8. FIG. 1 is a schematic sectional view of the obtained optical multicore connector 37.

Next, the optical multi-core connector 37 and 250 μ
Optical integrated circuit board 3 having three optical waveguides 34 at m intervals
3 was joined. At that time, a stripe-shaped pattern 36 having two sides 1 mm on both sides from the position corresponding to the center position of the optical fiber is formed on the optical integrated circuit substrate 33 as a registration mark by vapor deposition of metallic chromium and lift-off. It was formed by doing. First, as the guide plate, transparent glass plates 13 and 14 having a width of 1.5 mm, a length of 5 mm and a thickness of 0.5 mm are used.
On the optical fiber holding substrate 12 and the end cross section 16 of the substrate 12.
It was arranged and adhered so as to protrude by a length of 2.5 mm. Next, the optical integrated circuit board 33 was arranged with its end cross section 17 facing the end cross section 16 of the optical fiber holding substrate 12, and was brought close to the lower surfaces of the transparent glass plates 13 and 14.
Then, monochromatic light was applied to the optical integrated circuit board 33 through the transparent glass plates 13 and 14. Then the transparent glass plates 13, 1
Since the surface of No. 4 and the surface of the optical integrated circuit board 33 are not parallel, interference fringes were observed. When the surfaces of the transparent glass plates 13 and 14 and the surface of the optical integrated circuit board 33 are brought closer to each other,
The interference fringes moved and stopped when both surfaces touched at some point. Following that, the transparent glass plates 13, 1
The tilting positional relationship between the surface of No. 4 and the surface of the optical integrated circuit substrate 33 was adjusted so that the distance between the interference fringes was increased, and both surfaces were made parallel. Thus, the transparent glass plates 13, 14
The optical fiber holding substrate 12 and the optical integrated circuit substrate 33 were adhered in parallel to each other.

Furthermore, the end cross section 16 of the optical fiber holding substrate 12 was brought into close contact with the end cross section 17 of the optical integrated circuit board 33 while maintaining the above-mentioned close contact state. Then, in order to align the both substrates in the horizontal direction, the alignment marks 35 and 36 formed on the both substrates are exactly aligned with each other at both the end cross sections 16 and 17. I chose Thereafter, an ultraviolet curable resin was impregnated between the optical integrated circuit board 33 and the transparent glass plates 13 and 14 and cured by irradiation with ultraviolet light. Finally, until the optical fiber 8 hits the end cross section 17 of the optical integrated circuit board 33, the optical fiber holding board 1
It was pushed along the groove 51 of 2. FIG. 2 is a perspective view schematically showing the manufactured joined body 38 of the optical fiber holding substrate and the optical integrated circuit substrate. As described above, when the optical multi-core connector 37 and the optical integrated circuit board 33 are joined together, no increase in connection loss due to a broken piece missing from the optical multi-core connector 37 is observed, and the optical fiber 8 and the optical waveguide 34 are connected. The connection loss of each was 0.5 dB or less.

[Example 2] An optical fiber holding substrate was manufactured through the steps of FIGS. 4 (a) to 4 (f). However, since the depths of the grooves are made different, the groove 53 of FIG.
And First, the first silicon single crystal substrate 23 having a plate surface orientation of (100) and the second silicon single crystal substrate 24 having a plate surface orientation of (110) are mirror-faced to each other in an oxygen atmosphere,
After heat treatment at 1100 ° C. for 20 minutes to form silicon oxide layers 21 and 22 having a thickness of 0.25 μm on the surfaces of these substrates, the silicon single crystal substrate 2
Mirror surfaces of 3 and 24 are piled up and 1100 in oxygen atmosphere
It heat-processed at 10 degreeC for 10 minutes. By this treatment, a uniform silicon oxide layer 25 having a thickness of 0.50 μm was formed between the first silicon single crystal substrate 23 and the second silicon single crystal substrate 24 (FIG. 4A). Next, the second silicon single crystal substrate 24 was polished to a thickness of 57 μm (FIG. 4B). The surface of the second silicon single crystal layer 24 was oxidized to form a silicon oxide layer 26 having a thickness of 0.5 μm (FIG. 4 (c)). And this silicon oxide layer 2
6 is coated with photoresist 28, then exposed and developed to 2
Three windows each having a width of 124 μm and a length of 30 mm were formed at intervals of 50 μm (FIG. 4C). Then, using this photoresist pattern 28 as a mask, HF: HFN ₄ : H ₂
The silicon oxide layer 26 was removed with an aqueous solution of hydrofluoric acid having a composition of O = 1: 15: 5 (FIG. 4 (d)). Further, through the opening, the second silicon single crystal layer 24 is
It was removed by a 50 wt% KOH aqueous solution at 0 ° C. (FIG. 4).
(E)). Following this anisotropic etching, the silicon oxide layers 25 and 26 were removed with the hydrofluoric acid solution (FIG. 4).
(F)). The groove 53 thus manufactured has a depth of 6
The thickness was 7.5 μm, the width was 127 μm, and the length was 30 mm.

After that, the same test as in Example 1 was conducted.
The results were almost the same as in Example 1. That is,
When obtaining the optical multicore connector, no mechanical damage was observed due to the contact between each groove 52 and the optical fiber. Also,
When the optical multicore connector and the optical integrated circuit board were joined, no increase in the connection loss due to the broken pieces missing from the optical multicore connector was observed, and the connection loss between the optical fiber and the optical waveguide was 0. It was 5 dB or less.

[Comparative Example] An optical fiber holding substrate was prepared as shown in FIG. 3 (the groove 5 has a depth of 52.5 μm and a width 127.
After manufacturing an optical multicore connector in the same manner as in Example 1, the optical multicore connector and the optical integrated circuit board were joined together as shown in FIG. That is, while arranging the optical integrated circuit board 31 in which the optical waveguide 30 is embedded below the surface so as to face the surface of the optical multicore connector 10 in which the core portion of the optical fiber 8 projects from the surface, And the end faces of the optical waveguides 30 were overlapped with each other. Then, the optical axes of the end face of the optical fiber 8 and the end face of the optical waveguide 30 were aligned. As a result of manufacturing the joined body of the optical multicore connector 10 and the optical integrated circuit board 31 shown in FIG. 7 in this way, a sporadic connection loss, which is considered to be caused by the intrusion of fragments missing from the optical multicore connector onto the optical axis, An increase of 38% was observed.

[0029]

As described above, according to the present invention, the formed optical circuit has an extremely small problem that the propagation of light is hindered and the connection loss at the connecting portion between the optical fiber and the optical waveguide increases. It is also possible to provide a joined body of the same and an optical integrated circuit board.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an embodiment of an optical fiber holding substrate of the present invention.

FIG. 2 is a perspective view schematically showing an embodiment of a bonded body of the optical fiber holding substrate and the optical integrated circuit substrate of the present invention.

3A to 3F are cross-sectional views schematically showing one process of manufacturing a conventional optical fiber holding substrate.

4A to 4F are cross-sectional views schematically showing another process of manufacturing a conventional optical fiber holding substrate.

FIG. 5 is a schematic exploded perspective view showing a procedure for joining an optical multicore connector and an optical integrated circuit board in a comparative example.

FIG. 6 is a sectional view schematically showing an optical multicore connector in a comparative example.

FIG. 7 is a schematic perspective view showing a joined state of an optical multicore connector and an optical integrated circuit board in a comparative example.

FIG. 8 is a schematic exploded perspective view showing a procedure for joining the optical multicore connector and the optical integrated circuit board in the first embodiment.

FIG. 9 is a schematic exploded perspective view showing a procedure following that of FIG. 8 for joining the optical multicore connector and the optical integrated circuit board in the first embodiment.

[Explanation of symbols]

1, 23, 24 Silicon single crystal substrate 2 P-type impurity high-concentration diffusion layer 3, 52 Silicon single crystal 4, 21, 22, 25, 26 Silicon oxide layer 5, 27, 51, 53 Groove 5a, 51a Groove side Top and top of parts 6, 28 Photoresist pattern 7, 12 Optical fiber holding substrate 8 Optical fiber 9 Holding plate 10, 37 Optical multi-core connector 11, 32, 35, 36 Alignment mark 13, 14 Guide plate 15a, 15b Share Plane 16 End Cross Section of Optical Fiber Holding Substrate 17 End Cross Section of Optical Integrated Circuit Board 30, 34 Optical Waveguide 31, 33 Optical Integrated Circuit Board 38 Bonded Body of Optical Fiber Holding Board and Optical Integrated Circuit Board

Claims (4)

[Claims] 1. A high-concentration diffusion layer of p-type impurities is formed on a first silicon single crystal, and a second silicon single-crystal layer is formed on the high-concentration diffusion layer of p-type impurities. In a substrate having a groove for mounting an optical fiber on the concentration diffusion layer and having side portions of the groove parallel to the (111) plane of the second silicon single crystal layer, the depth of the groove is increased. Is larger than the radius of the optical fiber, an optical fiber holding substrate. 2. A silicon oxide layer is formed on the first silicon single crystal, and a second silicon single crystal layer is formed on the silicon oxide layer, and a groove for mounting an optical fiber is formed on the first silicon single crystal. And a side portion of the groove is formed of the silicon oxide layer and the second silicon single crystal layer, and a side portion of the groove is the second side.
In the substrate formed so as to be parallel to the (111) plane of the silicon single crystal layer, the optical fiber holding substrate, wherein the depth of the groove is larger than the radius of the optical fiber. 3. A bonded body of both substrates, wherein an optical axis of an optical fiber fixedly held on an optical fiber holding substrate and an optical axis of an optical waveguide formed on an optical integrated circuit substrate are aligned with each other. The optical fiber holding substrate according to claim 1 or 2 and the optical integrated circuit substrate are joined together at their end cross-sections so that the surfaces of both substrates share the same plane. A joined body of an optical fiber holding substrate and an optical integrated circuit substrate characterized by the above. 4. The optical fiber holding substrate according to claim 3, wherein the surface of the optical fiber holding substrate and the surface of the optical integrated circuit substrate share the same plane, and therefore, a transparent guide plate extending over both surfaces is provided. And an optical integrated circuit board.