JP2021148852A - Photoelectric fusion module and manufacturing method therefor - Google Patents

Abstract

To enable connection with an optical circuit chip to be appropriately performed.SOLUTION: The photoelectric fusion module comprises: an optical circuit chip 10 including a support substrate 1, a clad 2 formed on the support substrate and an optical waveguide core 4 buried in the clad; an electronic circuit board 20 having an optical fiber connecting terminal 20a and on which the optical circuit chip is installed at a prescribed position; and an optical path conversion unit 15 for converting the optical path of the optical waveguide core. The optical path conversion unit includes an end part 4a of the optical waveguide core provided at a prescribed point of the optical circuit chip, a connecting waveguide core 13 for connecting the end part and the optical fiber connecting terminal, and a seal layer 14 formed covering the connecting waveguide core.SELECTED DRAWING: Figure 1

Description

The present invention relates to a photoelectric fusion module and a method for manufacturing the same, and relates to, for example, an optical connection for connecting a silicon photonics chip and an external optical fiber.

The photoelectric fusion module integrates an optical integrated circuit and an electronic circuit. This optical integrated circuit integrates, for example, a light receiving element such as silicon photonics, a light modulation element, and a wavelength merging / demultiplexing as one circuit. In order to connect to the outside, it is necessary to connect the optical integrated circuit and the optical fiber.

For example, Patent Document 1 discloses a technique of reflecting light in a right-angled direction with a mirror inclined at 45 degrees. Patent Document 2 discloses a technique of pressing and connecting an inclined optical fiber. Patent Document 3 discloses a grating coupler. Further, Non-Patent Document 1 discloses a technique of curving silicon and guiding it upward.

Special Table 2014-522999 Patent No. 6264832 Japanese Unexamined Patent Publication No. 11-281833

"Development of epoch-making optical input / output technology of silicon photonics", [online], January 28, 2016, National Institute of Advanced Industrial Science and Technology, [Search on January 25, 2nd year of Reiwa], Internet <URL: https //www.aist.go.jp/aist_j/new_research/2016/nr20160128/nr20160128.html>

In any of the above patent documents and non-patent documents, a method for appropriately connecting an optical integrated circuit (optical circuit chip) and an optical fiber has not been considered.
For example, in an optical integrated circuit, a plurality of waveguide cores may be arranged in parallel to input and output a plurality of lights in order to increase the number of channels. One optical fiber is usually thicker than the waveguide core. Therefore, the distance between the plurality of waveguide cores becomes about the same as the distance between the plurality of optical fibers. In other words, the size of the optical integrated circuit becomes about the same as the width of a plurality of arranged optical fibers.

Further, a large number of optical wirings are arranged in a high-density optical integrated circuit. Therefore, the waveguide core that connects the light receiving element or optical modulator that constitutes the optical integrated circuit to the other optical element needs to jump over the optical wiring and connect to the other optical element. That is, it is necessary to form a waveguide with a three-dimensional structure.

Therefore, an object of the present invention is to provide a photoelectric fusion module capable of appropriately connecting to an optical circuit chip and a method for manufacturing the same.

In order to solve the above problems, the photoelectric fusion module of the present invention comprises a support substrate (1), a clad (2) formed on the support substrate, and an optical waveguide core (4) embedded in the clad. Converts the optical path of the optical waveguide core and the electronic circuit board (20) having the optical circuit chip (10) including the optical circuit chip (10) and the optical fiber connection terminal portions (20a, 45) in which the optical circuit chip is installed at a predetermined position. An optical path conversion unit (15) is provided, and the optical path conversion unit includes an end portion (4a) of the optical waveguide core provided at a predetermined position of the optical circuit chip, the end portion, and the optical fiber connection terminal portion. It is characterized in that it is composed of a connecting waveguide core (13) and a sealing layer (14) formed so as to cover the connecting waveguide core. The symbols and characters in parentheses are the symbols and the like attached in the embodiments, and do not limit the present invention.

According to the present invention, the connection with the optical circuit chip can be appropriately performed.

It is sectional drawing of the photoelectric fusion module which is 1st Embodiment of this invention. It is a top view of the photoelectric fusion module of 1st Embodiment of this invention. It is explanatory drawing (1) explaining the formation method which forms a polymer waveguide in a photoelectric fusion module. It is explanatory drawing (2) explaining the formation method which forms the polymer waveguide in a photoelectric fusion module. It is explanatory drawing (3) explaining the formation method which forms a polymer waveguide in a photoelectric fusion module. It is explanatory drawing (4) explaining the formation method which forms the polymer waveguide in a photoelectric fusion module. It is explanatory drawing (5) explaining the formation method which forms a polymer waveguide in a photoelectric fusion module. It is explanatory drawing (6) explaining the formation method which forms the polymer waveguide in a photoelectric fusion module. It is sectional drawing of the photoelectric fusion module which is 2nd Embodiment of this invention. It is a top view of the photoelectric fusion module which is the 2nd Embodiment of this invention. It is sectional drawing of the photoelectric fusion module which is the 1st comparative example of this invention. It is sectional drawing of the photoelectric fusion module which is the 2nd comparative example of this invention.

Hereinafter, embodiments of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail with reference to the drawings. It should be noted that each figure is merely schematically shown to the extent that the present invention can be fully understood. Therefore, the present invention is not limited to the illustrated examples. Further, in each figure, common components and similar components are designated by the same reference numerals, and duplicate description thereof will be omitted.

(First Embodiment)
FIG. 1 is a cross-sectional view of the photoelectric fusion module according to the first embodiment of the present invention.
The photoelectric fusion module 100 includes an electronic circuit board 20, a silicon photo chip 10 as an optical circuit chip, and a polymer waveguide 15 as a connection waveguide. The silicon photochip 10 is mounted on the electronic circuit board 20 via a solder 11 having a thickness of Δt. Further, a ferrule 40 on which a tape-type optical fiber 35 is mounted is attached to the photoelectric fusion module 100.

The electronic circuit board 20 is equipped with an electronic circuit (for example, TIA (Trance Impedance Amplifier) 60 (FIGS. 9 and 10)) for driving the silicon photochip 10 and an electric connector 80 (FIGS. 9 and 10). The electronic circuit board 20 is formed with an optical fiber connection terminal portion 20a to which the ferrule 40 is attached and a recess 20b in which the silicon photochip 10 is arranged.

The silicon photochip 10 includes a silicon substrate 1 as a support substrate, a silicon waveguide 6 mounted on the upper surface of the silicon substrate 1, a spot size converter 7 provided at one end of the silicon waveguide 6, and a silicon waveguide 6. It includes an optical circuit connected to the other end (for example, a photodiode 70 (FIGS. 9 and 10)). That is, the spot size converter 7 is interposed between the silicon waveguide 6 and the polymer waveguide 15. The silicon substrate 1 is formed with a recess 1a. The recess 1a has, for example, a depth D = about 17 μm and a length L in the propagation direction = about 100 μm.

The silicon waveguide 6 is composed of a lower clad layer 2, a silicon core 4, and an upper clad layer 5. The silicon core 4 has a rectangular cross section perpendicular to the drawing, and has a depth direction of about 480 nm and a height direction of about 220 nm on the paper surface. The spot size converter 7 has a function of increasing the diameter of the light emitted from the silicon waveguide 6. On the contrary, the spot size converter 7 has a function of reducing the diameter of the light incident on the silicon waveguide 6.

The polymer waveguide 15 is composed of a first polymer clad 12, a polymer core 13 as a connecting waveguide core, and a second polymer clad 14 as a sealing layer. The first polymer clad 12 and the second polymer clad 14 are made of the same photosensitive polymer. The polymer core 13 is composed of a photosensitive polymer having a higher refractive index than the first polymer clad 12 and the second polymer clad 14. Specifically, when the wavelength is 1550 μm, the refractive index of the first polymer clad 12 and the second polymer clad 14 is 1.547, and the refractive index of the polymer core 13 is 1.577. The polymer core 13 is formed in a 7 μm square.

The first polymer clad 12 fills the recess 1a of the silicon substrate 1. The polymer core 13 is connected to the spot size converter 7 and has an inclined portion 13a and a parallel portion 13b parallel to the silicon substrate 1. The parallel portion 13b extends not only to the recess 1a but also to the upper part of the electronic circuit board 20. When the spot size converter 7 is not provided, the polyma core 13 may be connected to one end of the silicon waveguide 6. The second polymer clad 14 is deposited on the upper surfaces of the polymer core 13 and the silicon waveguide 6. The upper surface of the second polymer clad 14 is deposited in parallel with the electronic circuit substrate 20 without being inclined.

FIG. 2 is a plan view of the photoelectric fusion module according to the first embodiment of the present invention.
As described with reference to FIG. 1, the photoelectric fusion module 100 includes an electronic circuit board 20, a silicon photochip 10, and a polymer waveguide 15. A ferrule 40 on which a tape-type optical fiber 35 is mounted is attached to the photoelectric fusion module 100. The ferrule 40 is omitted by a virtual line.

The tape-type optical fiber 35 is obtained by bundling a plurality of optical fiber strands 30 with an adhesive 33. In the silicon photo chip 10, a plurality of silicon cores 4 described with reference to FIG. 1 are arranged side by side. In the polymer waveguide 15, a plurality of polymer cores 13 described with reference to FIG. 1 are arranged side by side. The distance between the plurality of optical fiber strands 30 is wider than the distance between the plurality of silicon waveguides 6 (silicon cores 4) provided in the silicon photochip 10. Therefore, the plurality of polyma cores 13 are arranged so that the distance gradually increases as the distance from the end portion 4a of the silicon core 4 increases.

(Production method)
Next, among the manufacturing methods for manufacturing the photoelectric fusion module 100, a forming method for forming the polymer waveguide 15 characteristic of the present embodiment will be described.
3 to 8 are explanatory views illustrating a forming method for forming a polymer waveguide in the photoelectric fusion module.

In FIG. 3 (SP1), the manufacturer joins the recess 20b of the electronic circuit board 20 and the silicon photochip 10 with solder 11 in advance. Then, the manufacturer forms the recess 1a on the upper surface of the silicon photo chip 10 by dry etching.

In FIG. 4 (SP2), the manufacturer applies the photosensitive polymer 91 by spin coating. The spin coating conditions are, for example, 5000 rpm and 600 seconds. As a result, the photosensitive polymer 91 is filled in the recess 1a and laminated on the upper surface 20c of the electronic circuit substrate 20 and the upper surface 5a of the upper clad layer 5. As the photosensitive polymer 91, for example, NP-214 manufactured by Nissan Chemical Industries, Ltd. is used.

In FIG. 5 (SP3), the manufacturer performs drawing and development processing on the photosensitive polymer 91 by a laser drawing device (not shown) to provide the inclined portion 91a. The laser drawing apparatus is, for example, DWL-66 + manufactured by Heidelberg. That is, the manufacturer reduces the amount of laser light in the vicinity of the spot size converter 7 and increases the amount removed by development. On the other hand, on the upper surface 20c side of the electronic circuit board 20, the amount of laser light is gradually (linearly) increased to reduce the amount removed by development. The lower clad layer 2 is arranged from the surface 1b of the silicon photochip 10 (upper surface 5a of the upper clad layer 5) to a position H1 = about 5 μm below. The upper surface 12a of the first polymer clad 12 is arranged at a position of L = 100 μm in the optical signal propagation direction and at a position of H2 = about 10 μm above the surface 1b of the silicon photochip 10. Further, the upper surface 5a of the upper clad 5 is not exposed to laser light, and the photosensitive polymer 91 is completely removed by development. As a result, the first polymer clad 12 is formed.

In FIG. 6 (SP4), the photosensitive polymer 92 is applied to the upper surface 12a of the first polymer clad 12 and the upper surface 5a of the upper clad layer 5 by spin coating. As the photosensitive polymer 92, for example, NP-010 manufactured by Nissan Chemical Industries, Ltd. is used.

In FIG. 7 (SP5), the manufacturer performs drawing and development processing by a laser drawing apparatus to form a polymer waveguide core 13 along the upper surface 12a of the first polymer cladding 12. At this time, the manufacturer reduces the amount of laser light in the vicinity of the spot size converter 7 and increases the amount of removal by development. On the other hand, on the upper surface 20c side of the electronic circuit board 20, the amount of laser light is increased and the amount removed by development is reduced.

In FIG. 8 (SP6), the manufacturer applies the photosensitive polymer 91 by spin coating to a height of H3 = 10 μm. Further, the manufacturer irradiates the photosensitive polymer 91 with a laser beam to cure the photosensitive polymer 91. As a result, the second polymer clad 14 is formed, and the photoelectric fusion module 100 is manufactured.

As described above, in the photoelectric fusion module 100 of the present embodiment, the polymer waveguide 15 is interposed between the plurality of silicon cores 4 of the silicon photochip 10 and the plurality of optical fiber strands 30 of the tape-type optical fiber 35. It has been inserted. Therefore, even if the distance between the plurality of silicon cores 4 is narrower than the distance between the plurality of optical fiber wires 30, the distance between the polymer waveguide cores 13 is gradually changed to gradually change the distance between the silicon cores 4 and the optical fiber wires 30. Can be optically connected to and from. That is, the photoelectric fusion module 100 having the compact and high-density silicon photochip 10 can be optically connected to the plurality of optical fiber strands 30 while maintaining the distance between the plurality of silicon cores 4.

Further, even if the center heights of the plurality of silicon cores 4 and the center heights of the plurality of optical fiber strands 30 are different, the silicon core 4 and the polymer waveguide core can be provided by providing the inclined portion 13a in the polymer waveguide core 13. 13 can be optically connected.

(Second Embodiment)
FIG. 9 is a cross-sectional view of the photoelectric fusion module according to the second embodiment of the present invention, and FIG. 10 is a plan view thereof.
The photoelectric fusion module 200 includes an electronic circuit board 21, a silicon photochip 10, and a polymer waveguide 15, as in the first embodiment. The electronic circuit board 21 is an electronic circuit board including a TIA 60, an optical connector 45, an electric connector 80, and a wiring pattern 25. Here, the silicon photochip 10 is arranged in the recess 20b of the electronic circuit board 21, but the TIA 60 is attached to the electronic circuit board 21, and a plurality of pads 61 are formed.

The silicon photochip 10 is formed with a photodiode 70 as an optical functional element, an optical wiring 75, and a plurality of pads 61. The photodiode 70 is a light receiving element that converts the light emitted from the polymer waveguide core 13 into an electric current. The TIA 60 is an electronic circuit that converts the output current of the photodiode 70 into a voltage. The electric connector 80 is connected by a wiring pattern 25. The pad 61 of the TIA 60 and the wiring pattern 25 are connected by a wire.

The optical wiring 75 is formed of a silicon waveguide 6. The polymer waveguide core 13 intersects the optical wiring 75 in a plan view so as to jump over the optical wiring 75. Therefore, it is meaningful to dispose the polymer waveguide core 13 at a position higher than that of the silicon waveguide 6.

(First comparative example)
FIG. 11 is a cross-sectional view of the photoelectric fusion module which is the first comparative example of the present invention.
The photoelectric fusion module 300 includes an electronic circuit board 20 and a silicon photochip 10 as in the first and second embodiments, but does not include a polymer waveguide 15 (FIG. 1).
Further, the photoelectric fusion module 300 is different in that one end of the optical fiber wire 30 is placed on the upper surface 20c of the electronic circuit board 20 and the optical fiber wire 30 is fixed by the optical fiber fixing jig 37. By arranging the spot size converter 7 and the end face of the optical fiber wire 30 close to each other, end face coupling is performed.

If there is only one silicon core 4 of the silicon photo chip 10, end face bonding is possible. However, the silicon photochip 10 is usually minute and dense. Therefore, when a plurality of silicon cores 4 are arranged, the arrangement interval of the silicon cores 4 and the arrangement interval of the same number of optical fiber strands 30 are different, which makes end face coupling difficult.

(Second comparative example)
FIG. 12 is a cross-sectional view of a photoelectric fusion module which is a second comparative example of the present invention.
Similar to the first and second embodiments and the first comparative example, the photoelectric fusion module 400 includes an electronic circuit board 20 and a silicon photochip 16, and does not include a polymer waveguide 15 (FIG. 1). However, the silicon photochip 16 differs from the silicon photochip 10 in that it includes a grating coupler 17 instead of the spot size converter 7. The photoelectric fusion module 400 is also different in that the optical fiber wire 30 is fixed to the electronic circuit board 20 by the optical fiber fixing jig 38.

The grating coupler 17 is an element that emits modulated light emitted by an optical modulation element (not shown) toward the upper surface 5a of the upper clad layer 5. The optical fiber fixing jig 38 fixes the end of the optical fiber wire 30 toward the exit direction of the grating coupler 17.

The size of the grating coupler 17 is about 100 μm, but the size of the optical fiber fixing jig 38 is about 1 mm. Therefore, the structure of the photoelectric fusion module 400 is disadvantageous in that the silicon photochip 16 is highly integrated. On the other hand, in the photoelectric fusion module 200 of the second embodiment, since the polymer waveguide 15 is formed, the connection to the optical connector (for example, MT ferrule) becomes easy.

(Modification example)
The present invention is not limited to the above-described embodiment, and various modifications such as the following are possible.
(1) The second polymer clad 14 of each of the above embodiments was formed by spin-coating the same photosensitive polymer 91 as the first polymer clad 12, but if the polymer has the same refractive index as the first polymer clad 12. It does not have to be a photosensitive polymer.

1 Silicon substrate (support substrate)
2 Lower clad layer 3 Silicon layer 4 Silicon core (optical waveguide core)
5 Upper clad layer 6 Silicon waveguide 7 Spot size converter 10, 16 Silicon photo chip (optical circuit chip)
12 1st polymer clad 13 Polymer waveguide core (connection waveguide core)
14 Second polymer clad (sealing layer)
15 Polymer waveguide (connecting waveguide)
20, 21 Electronic circuit board 30 Optical fiber wire 35 Tape type optical fiber 40 Ferrule 45 Optical connector (optical fiber connection terminal)
60 TIA (electronic circuit)
70 Photodiode (optical functional element)
80 Electric connector (Electrical terminal connection)
100,200,300 photoelectric fusion module

Claims (9)

An optical circuit chip including a support substrate, a cladding formed on the support substrate, and an optical waveguide core,
An electronic circuit board having an optical fiber connection terminal and having the optical circuit chip installed at a predetermined position.
It is provided with an optical path conversion unit that converts the optical path of the optical waveguide core.
The optical path conversion unit
The end of the optical waveguide core provided at a predetermined position on the optical circuit chip, and
A connection waveguide core that connects the end portion and the optical fiber connection terminal portion,
A sealing layer formed over the connecting waveguide core and
A photoelectric fusion module characterized by being composed of. The photoelectric fusion module according to claim 1, wherein the connecting waveguide core and the sealing layer are formed of polymers having different refractive indexes. A plurality of the optical waveguide core and the connection waveguide core are arranged side by side.
The photoelectric fusion module according to claim 1 or 2, wherein the distance between the plurality of connected waveguide cores gradually increases as the distance from the ends of the plurality of optical waveguide cores increases. The photoelectric fusion module according to any one of claims 1 to 3, wherein the connection waveguide core is inclined with respect to the electronic circuit board. The optical circuit chip includes an optical functional element and an optical wiring that is not connected to the optical functional element.
The photoelectric fusion module according to claim 4, wherein the connection waveguide core is arranged so as to jump over the optical wiring. The photoelectric fusion module according to any one of claims 1 to 5, wherein a spot size converter is interposed between the end portion and the connecting waveguide core. The photoelectric fusion module according to any one of claims 1 to 6, wherein the electronic circuit board includes an electronic circuit and an electric terminal connecting portion connected to the electronic circuit. A method for manufacturing a photoelectric fusion module including a support substrate, an optical circuit chip, and an electronic circuit substrate on which the optical circuit chip is arranged.
A coating step of applying the first photosensitive polymer on the support substrate, and
A drawing step of drawing a laser directly on the applied first photosensitive polymer, and
It is provided with a developing step of developing the first photosensitive polymer drawn in the drawing step.
In the drawing step, the laser is weakly irradiated on the silicon core side of the optical circuit chip, and strongly irradiated as the distance from the silicon core increases.
A method for manufacturing a photoelectric fusion module, which comprises forming a clad having an inclined structure in the developing step. A core forming process in which a second photosensitive polymer having a refractive index higher than that of the first photosensitive polymer is applied onto the clad having an inclined structure.
8. The eighth aspect of the present invention is further comprising an upper clad forming process of applying the first photosensitive polymer or a polymer having the same refractive index as the first photosensitive polymer on the second photosensitive polymer. A method for manufacturing a photoelectric fusion module.

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