JP4194515B2 - Two-dimensional optical waveguide device and optoelectronic wiring board using the same - Google Patents

Description

The present invention relates to a two-dimensional optical waveguide device (two-dimensional optical waveguide circuit) and a photoelectric fusion wiring substrate using the same (a wiring substrate in which an electric wiring layer and an optical wiring layer (optical waveguide device) are mixedly mounted). .

With the rapid spread of today's mobile phones and personal information terminals, there is a demand for further downsizing, weight reduction and higher functionality of devices. However, miniaturization, weight reduction, and higher functionality have led to higher speed and higher integration of circuit boards, and there is an urgent need to deal with problems such as signal delay and EMI (Electromagnetic Interference). As a means to solve these problems, optical wiring technology that can overcome or reduce signal delay, signal degradation, and electromagnetic interference noise radiated from wiring, which has been a problem in conventional electrical wiring, and enables high-speed transmission. Is expected. There are the following devices using the advantages of this optical wiring.

In one optical circuit board, the optical wiring section and the electrical wiring section are separated, and an optical switch or optical modulator provided on the substrate is driven by a voltage signal from an electronic device to provide an optical waveguide provided on the substrate. The light propagating light is modulated, thus converting the electric signal into an optical signal and transmitting it, and further converting the optical signal into an electric signal by a light receiving element provided on the base body or another base body. Alternatively, a signal is transmitted to the same electronic device (see Patent Document 1). In other optical waveguide devices, a mirror tilted by 45 degrees is formed in a linear polymer waveguide in order to efficiently combine light incident / exit perpendicular to the optical waveguide (Patent Document). 2).
JP 9-96746 A Japanese Unexamined Patent Publication No. 2000-199827

The method of Patent Document 1 described above is a method in which problems in electrical wiring are compensated by optical wiring (optical interconnect). However, since the optical wiring is a transmission line (linear polymer waveguide), an electrical / optical signal or A place to perform optical / electrical signal conversion is defined. In the method of Patent Document 2, a light-emitting element is mounted so that an optical signal is efficiently coupled to a linear optical waveguide having a mirror inclined at 45 degrees at the end, and the linear optical waveguide is propagated. It is difficult to mount a photoreceiver so as to efficiently receive an optical signal because a high degree of alignment accuracy is required. Moreover, since it is a linear optical waveguide, when forming a some optical waveguide, the position of a light emitting element and a light receiving element is restrict | limited, and the freedom degree of design is small. Furthermore, it is not considered that the transmission efficiency and transmission speed of the optical signal are reduced.

Accordingly, in view of the above problems, the two-dimensional optical waveguide device of the first invention according to the present application includes at least a sheet-like core layer, and an optical path changing structure in the vicinity of a place where the light emitting element and the light receiving element are to be disposed. A two-dimensional optical waveguide device in which a body is disposed, wherein the height of the optical path converting structure disposed in the vicinity of the light emitting element and the height of the optical path converting structure disposed in the vicinity of the light receiving element are The thickness of the core layer corresponding to the place where the light emitting element is to be arranged is substantially the same as the thickness of the core layer corresponding to the place where the light receiving element is to be arranged , and is disposed in the vicinity of the light receiving element . The uppermost part of the optical path changing structure is in contact with the light receiving surface of the light receiving element . Here, in the structure in which the light emitting element and the light receiving element are arranged on the core layer, the distance from the light emitting element exit to the top of the structure where the light emitted from the light emitting element is combined to change the optical path. However, the distance is set to be larger than the distance from the uppermost part of the structure to which the light propagated through the core layer is combined to change the optical path to the light receiving surface of the light receiving element. In this configuration, more light emitted from the light emitting element can be guided to the optical waveguide layer, and light propagated through the optical waveguide layer can be efficiently coupled to the light receiving element.

The method for manufacturing a two-dimensional optical waveguide device according to the second invention of the present application includes a step of changing the thickness of the core layer, and in this step, by etching a part of the core layer, Including a step of changing the thickness or changing the thickness of the core layer, wherein a material having photosensitivity is used as a material for forming the core layer, and a part of the material for forming the core layer It is characterized by changing the thickness of the core layer by exposing and developing the film. In these manufacturing methods, the step of changing the thickness of the core layer can be performed with high accuracy, and in particular, when a material having photosensitivity is used, the manufacturing can be performed with fewer steps.

Further, a photoelectric fusion wiring board according to a third aspect of the present invention is a photoelectric fusion wiring board formed so that the above-described two-dimensional optical waveguide device can be electrically connected to an electric circuit board. The present invention is characterized in that a part or all of the signals on the substrate are wired by transmitting and receiving an optical signal using a two-dimensional optical waveguide device.

According to the present invention having the above-described configuration, in the two-dimensional optical waveguide device or the two-dimensional optical waveguide circuit, the distance from the emission port of the light emitting element to the apex of the optical path conversion structure for the light emitting element, and the optical path conversion for the light receiving element By controlling the distance from the top of the structure to the light-receiving surface of the light-receiving element, it is possible to increase the optical coupling efficiency to the two-dimensional optical waveguide layer, and to receive the light propagated in the two-dimensional optical waveguide layer As a result, it is possible to efficiently couple to the element, and as a result, it is possible to increase the transmission efficiency (reliability) and transmission speed of optical signal transmission.

  The two-dimensional optical waveguide device and optoelectronic interconnection substrate of the present invention have the basic configuration as described above, but the following modes are possible based on this basic configuration. An embodiment of the present invention will be described. In the present invention, when the light emitted from the light emitting element is coupled to the core layer in the two-dimensional optical waveguide circuit, and when the light guided through the core layer is coupled to the light receiving element, a method of increasing each coupling efficiency, This is done by controlling the distance between the light path conversion structure disposed in the vicinity of the light emitting element and the light receiving element and the light emitting surface of the light emitting element and the light receiving surface of the light receiving element.

More specifically, the thickness of the core layer corresponding to the place where the light emitting element is to be arranged can be made larger than the thickness of the core layer corresponding to the place where the light receiving element is to be arranged. Thereby, the distance from the exit of the light emitting element to the top of the structure where the light emitted from the light emitting element is combined and the optical path is changed, and the structure where the light propagated through the core layer is combined and the optical path is changed The distance from the uppermost part of the light receiving element to the light receiving surface of the light receiving element can be different. Here, the thickness of the core layer can be changed gradually. In such a configuration, the light path conversion structure for the light emitting element and the light path conversion structure for the light receiving element can be substantially the same height.

In addition, the shape of the structure in which light emitted from the light emitting element is combined to change the optical path may be different from the shape of the structure in which light propagating through the core layer is combined to change the optical path. Thereby, the distance from the exit of the light emitting element to the top of the structure where the light emitted from the light emitting element is combined and the optical path is changed, and the structure where the light propagated through the core layer is combined and the optical path is changed The distance from the uppermost part of the light receiving element to the light receiving surface of the light receiving element can be made different so that the light receiving efficiency can be increased. In this case, the thickness of the core layer can be made substantially uniform.

In addition, the thickness of the core layer corresponding to the location where the light receiving element is to be arranged is the same as the height of the structure in which the light propagating through the core layer is combined and the optical path is changed, and is disposed in the vicinity of the light receiving element. Further, the uppermost part of the optical path changing structure and the light receiving surface of the light receiving element may be in contact with each other. As a result, the light receiving efficiency can be increased.

Further, the light emitting element and the light receiving element may be arranged as a single element or a plurality of elements (for example, arranged in an array). Furthermore, the optical path conversion structure has a hemispherical shape, a conical shape, or a polygonal pyramid shape, and the optical path conversion structure is formed in the vicinity of the light emitting element so that the light emitted from the light emitting element is coupled. Is configured so that the radiation angle can be changed, and the optical path conversion structure is a two-dimensional light beam that emits light emitted from the light emitting element coupled thereto as beam light or diffused light having a spread angle corresponding to the radiation angle. The optical path can be changed so as to propagate inside the waveguide.

By using a two-dimensional optical waveguide layer as the optical waveguide, the arrangement of light emitting elements for converting electrical signals into optical signals and light receiving elements for converting optical signals into electrical signals is not so limited, and two A two-dimensional optical waveguide device and an optoelectronic wiring board that can flexibly reconfigure an optical signal using the entire two-dimensional optical waveguide layer can be easily realized.

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings and more specific examples.
(Example 1)
FIG. 1 is a diagram showing a two-dimensional optical waveguide circuit according to the first embodiment. In FIG. 1, 100 is a light emitting element, 102 is a light receiving element, 104 is an incident side optical path changing structure, 106 is an outgoing side optical path changing structure, 108 is a cladding layer, and 110 is a core layer. The light emitting element 100, the light receiving element 102, and the optical path conversion structures 104 and 106 are configured such that light emitted from the light emitting element 100 is optically converted by the incident-side optical path conversion structure 104, and the optical path converted light is the core of the two-dimensional optical waveguide. The light propagates through the layer 110, and the propagated light is optically path-converted by the exit-side optical path conversion structure 106 and is coupled to the light receiving element 102. The sheet-like two-dimensional optical waveguide layer is composed of a core layer 110 (a portion having a relatively high refractive index) and a clad layer 108 (a portion having a relatively low refractive index) by a combination of materials having different refractive indexes. In FIG. 1, a clad layer is not formed on the core layer 110, but may be formed if necessary. In this example, a polysilane resin having a refractive index of 1.60 was used for the core layer 110, and a polysilane resin having a refractive index of 1.55 was used for the cladding layer 108. A hemispherical structure with a radius of 25 μm was used as the optical path changing structure. In the present embodiment, the distance between the light receiving surface of the light receiving element 102 and the apex of the emission side optical path changing structure 106 is eliminated (the light receiving element 102 and the emission side optical path changing structure 106 are in contact), and the light emitting element 100 The thickness of the core layer 110 is controlled so that the distance between the light exit and the apex of the incident-side optical path conversion structure 104 is at least 75 μm or more. With respect to the latter, if there is such a distance, the light from the light emitting element 100 having a certain radiation angle is optically changed without returning to the light emitting element 100 side so much, and is within the core layer 110 of the two-dimensional optical waveguide. Will begin to propagate.

Next, a method for manufacturing the two-dimensional optical waveguide device shown in this embodiment will be described. FIG. 2 is a schematic diagram for explaining a method of manufacturing a two-dimensional optical waveguide device. In the figure, 200 is a substrate, 202 is a cladding layer, 204 is an optical path changing structure material, 206 is a photomask, 208 is a structure having a first shape, 210 is a structure having a second shape, and 212 is a reflective film. Material, 214 is a reflective film, 216 is a core layer, 218 is a light emitting element, 220 is a light receiving element, and 222 is an element driving pad.

  First, as shown in FIG. 2 (a), a polysilane-based resin, which is a clad layer material, is applied onto a tilted substrate (for example, Si wafer) 200 using a spin coater and baked to form a clad layer having a thickness of 20 μm. 202 is formed. Thereafter, as shown in FIG. 2 (b), a photosensitive thermoplastic material 204, which is an optical path changing structure material, is applied using a spin coater, and a photomask 206 (a circular pattern light transmitting portion having a radius of 25 μm is formed). Exposure). These materials are formed with a substantially uniform thickness as shown in the figure by spin coating at an appropriate rotational speed corresponding to the viscosity of each material.

Thereafter, as shown in FIG. 2 (c), a structure 208 having a first cylindrical shape having a radius of 25 μm and a height of 17 μm is formed through a development process. In this state, as shown in FIG.
Heated for 4 minutes on a hot plate at ℃, melted and re-solidified the structure 208 with the above first shape made of photosensitive thermoplastic material, transformed into a hemisphere with a radius of 25μm The structure 210 having the second shape is formed.

Next, as shown in FIG. 2 (e), Cr / Au as the reflective film material 212 is vapor-deposited using an electron beam vapor deposition apparatus. With this reflective film, it is possible to obtain a reflectance of 90% or more for light having a wavelength of 660 nm. Subsequently, as shown in FIG. 2 (f), a photoresist is applied using a spin coater, and after the exposure / development process, only the surface of the structure 210 having the second shape deformed into a hemisphere is covered. Thus, a resist mask (not shown) is formed, and then wet etching is performed in the order of Au and Cr, and the reflective film 214 is formed only on the surface of the structure 210 having the second shape deformed into a hemisphere.

Subsequently, as shown in FIG. 2 (g), a polysilane resin having a refractive index larger than that of the clad layer 202 is applied using a spin coater and baked to form the core layer 218. Here, the material of the core layer 218 is spin-coated at an appropriate rotation speed according to the viscosity of the material, and as shown in the drawing, the incident side (left side) optical path changing structure 210 is relatively thick and the emission side. (Right side) The optical path changing structure 210 can be formed relatively thin.

Next, as shown in FIG. 2 (h), the structure 210 having the hemispherical second shape is coupled so that the emitted light from the light emitting element 218 is coupled to the structure 210 having the hemispherical second shape. An element driving pad (Ti / Au) 222 is formed on the core layer 216 in order to mount the light emitting element 218 and the light receiving element 220 on the core layer 216 such that the propagation light coupled to the light receiving element 220 is coupled. . Subsequently, as shown in FIG. 2 (i), the light emitting element 218 and the light receiving element 220 are mounted on the element driving pad 222 by using a flip chip bonder to obtain a two-dimensional optical waveguide circuit.

As shown in FIG. 3, the two-dimensional optical waveguide circuit manufactured in this way can reduce the amount of light emitted to the outside as compared with the conventional one, so that the transmission efficiency of the optical signal can be increased. (Figure 3 (a) shows the conventional one,
FIG. 3 (b) shows this example). In addition, since the structure 210 having the second shape deformed into a hemisphere having the reflective film 214 is disposed, the light incident from the upper surface of the hemisphere structure 210 is efficiently scattered, and the core layer Propagated throughout 216. On the other hand, the light propagating through the core layer 216 is scattered by the structure 210 having the second shape deformed into a hemisphere, and the light is emitted above the hemisphere structure 210.

  In this embodiment, polysilane resins having different refractive indexes were used as the combination of the cladding layer and the core layer material. However, the present invention is not limited to this, and the core layer material has a higher refractive index than the cladding layer material. If so, a combination using a polyimide resin or an acrylic resin may be used. Further, the value of the refractive index is not limited to the above value of the embodiment.

In this embodiment, the Si wafer is used as the substrate. However, the present invention is not limited to this, and a glass substrate or a ceramic substrate may be used. Further, the substrate may be a resin film having a refractive index smaller than that of the core layer material, and the resin film itself functions as a cladding layer to obtain a foldable two-dimensional optical waveguide device. In addition, although the thickness of the cladding layer is 20 μm, the thickness is not limited to this and may be any layer thickness.

In this embodiment, the structure 208 having the first shape has a cylindrical shape with a radius of 25 μm and a height of 17 μm. However, the present invention is not limited to this, and may be a shape such as an elliptical column or a rectangular column or any size. In addition, the hemispherical optical path conversion structure 210 having a radius of 25 μm was used, but the invention is not limited to this, and it may be arbitrarily determined depending on the emission angle of the light emitting element, the refractive index of the optical waveguide layer, and the optical waveguide layer thickness. Can be selected. Moreover, although the optical path changing structure is hemispherical, it is not limited to this, and may be a wedge shape, a conical shape, or a polygonal pyramid shape.

In this embodiment, the optical waveguide layer is a two-dimensional optical waveguide layer (film-shaped optical waveguide). However, the present invention is not limited to this, and the line waveguide (one-dimensional optical waveguide) or the two-dimensional optical waveguide layer ( An optical waveguide layer having a structure in which both a film-shaped optical waveguide) and the line waveguide (one-dimensional optical waveguide) are mixed may be used. The line waveguide is obtained, for example, by producing a line-shaped portion having a relatively large effective refractive index in the film-shaped optical waveguide layer (for example, forming a convex line-shaped portion on the optical waveguide layer).

  In this example, a core layer having a gradually changing thickness was formed using a substrate having a surface gradually inclined from one end portion toward the other end portion, but the following forms are also possible. It is. For example, using a substrate having an inclined surface that gradually descends from both sides or from four sides to the center, there is a core layer that gradually decreases in thickness from the center to the end (slowly roof A core layer whose thickness varies in the shape of a cone or a cone. Then, the light emitting element is arranged at the thick core layer at the center and the light receiving element is arranged at the thin core layer at the end. Furthermore, using a substrate having a surface having a plurality of (for example, two) gently sloping portions having a roof shape or a cone shape, a core layer is formed thereon as described above, and a thin boundary portion of the core layer (for example, In addition, it is also possible to divide the region for transmitting and receiving light between the light emitting element and the light receiving element into a plurality of parts with a boundary of the thickness of zero).

As described above, by adopting the configuration of Example 1, light emitted from the light emitting element is guided to the optical waveguide layer and light propagated through the optical waveguide layer is compared with the conventional configuration (see FIG. 3A). The efficiency of coupling to the light receiving element is increased, and the reliability and transmission speed of optical signal transmission are improved.

(Example 2)
FIG. 4 is a diagram illustrating a two-dimensional optical waveguide device according to the second embodiment. In FIG. 4, 400 is a light emitting element, 402 is a light receiving element, 404 is an incident side optical path changing structure, 406 is an outgoing side optical path changing structure, 408 is a cladding layer, and 410 is a core layer. In the light emitting element 400, the light receiving element 402, the incident side optical path changing structure 404, and the outgoing side optical path changing structure 406, the light emitted from the light emitting element 500 is optically changed by the incident side optical path changing structure 404, and the optical path is changed. The light is propagated through the core layer 410 of the two-dimensional optical waveguide, and the propagated light is optically path-converted by the exit-side optical path converting structure 406 and coupled to the light receiving element 402. The sheet-like two-dimensional optical waveguide layer is composed of a core layer 410 (portion having a relatively high refractive index) and a clad layer 408 (portion having a relatively low refractive index) by a combination of materials having different refractive indexes. Also in this example, a polysilane resin having a refractive index of 1.60 was used for the core layer 410, and a polysilane resin having a refractive index of 1.55 was used for the clad layer 408. A hemispherical structure with a radius of 25 μm was used as the optical path changing structure. In this embodiment, the distance between the light receiving surface of the light receiving element 402 and the apex of the emission side optical path conversion structure 406 is eliminated, and the distance between the exit of the light emitting element 400 and the apex of the incident side optical path conversion structure 404 is The size and shape of the incident-side optical path conversion structure 404 and the emission-side optical path conversion structure 406 are controlled while making the thickness of the core layer 410 substantially uniform so as to be at least 75 μm or more.

  Next, a method for manufacturing the two-dimensional optical waveguide layer shown in this embodiment will be described. FIG. 5 is a schematic diagram for explaining a method of manufacturing a two-dimensional optical waveguide circuit. In the figure, 500 is a substrate, 502 is a cladding layer, 504 is an optical path changing structure material, 506 is a photomask, 508 and 510 are structures having a first shape, 512 and 514 are structures having a second shape, 516 is a reflective film material, 518 is a reflective film, 520 is a core layer, 522 is a light emitting element, 524 is a light receiving element, and 526 is an element driving pad.

  First, as shown in FIG. 5 (a), a polysilane resin, which is a clad layer material, is coated on a substrate (for example, Si wafer) 500 having a uniform thickness using a spin coater and baked to form a clad having a thickness of 20 μm. Layer 502 is formed. Thereafter, as shown in FIG. 5 (b), a photosensitive thermoplastic material 504, which is an optical path changing structure material, is applied using a spin coater, and a photomask 506 (a circular pattern light transmitting portion having a radius of 25 μm and Exposure is performed using a circular pattern light transmission portion having a radius of 125 μm. Thereafter, as shown in FIG. 5 (c), structures 508 and 510 having a cylindrical first shape with a radius of 25 μm, a height of 17 μm, a radius of 125 μm, and a height of 17 μm are formed through a development process. In this state, as shown in FIG. 5 (d), the structures 508 and 510 having the first shape formed of the thermoplastic material having photosensitivity are heated on a hot plate at 150 ° C. for 4 minutes. A structure 512 having a second shape deformed into a hemisphere with a radius of 25 μm by melting and resolidifying by heat treatment and a structure having a second shape deformed into a substantially semi-elliptical sphere with a bottom radius of 125 μm and a height of 75 μm 514 is formed.

Next, as shown in FIG. 5 (e), Cr / Au (Cr thickness: 50 nm, Au thickness: 300 nm), which is the reflective film material 516, is deposited using an electron beam deposition apparatus. Subsequently, as shown in FIG. 5 (f), a photoresist 512 is applied using a spin coater, and after undergoing an exposure / development process, a structure 512 having a second shape deformed into a hemispherical shape and a substantially semi-elliptical spherical shape. A resist mask (not shown) is formed so as to cover only the surface of 514 and 514, and then etching is performed in the order of Au and Cr, and a structure 512 having a second shape deformed into a hemispherical shape and a substantially semi-elliptical spherical shape, A reflective film 518 is formed only on the surface of 514. Subsequently, as shown in FIG. 5 (g), a polysilane-based resin having a refractive index larger than that of the cladding layer 502 is applied using a spin coater and baked to form the core layer 520. At this time, the core layer 520 is formed with a substantially uniform thickness as shown in the figure by spin coating at an appropriate rotation speed according to the viscosity of the material.

Next, as shown in FIG. 5 (h), the structure 512 having a semispherical second shape is formed so that the emitted light from the light emitting element 522 is coupled to the structure 512 having a semispherical second shape. An element driving pad (Ti / Au) 526 is formed on the core layer 520 to mount the light emitting element 522 and the light receiving element 524 on the core layer 520 so that the propagating light coupled to the body 514 is coupled to the light receiving element 524. To do. Subsequently, as shown in FIG. 5 (i), the light emitting element 522 and the light receiving element 524 are mounted on the element driving pad 526 using a flip chip bonder to obtain a two-dimensional optical waveguide circuit.

In the two-dimensional optical waveguide circuit fabricated in this way, as shown in FIG. 6, the light emitted to the outside can be reduced compared to the conventional one, so that the transmission efficiency of the optical signal is increased. (Fig. 6 (a) shows the conventional one,
FIG. 6 (b) shows the example. In addition, since the structure 512 having the second shape deformed into a hemisphere having the reflective film 518 is disposed, the light incident from the upper surface of the hemisphere structure 512 is efficiently scattered and the core layer Propagated throughout 520. On the other hand, the light propagating through the core layer 520 is scattered by the structure 514 having the second shape deformed into a substantially semi-elliptical sphere, and is emitted above the structure 514 having a substantially semi-elliptical sphere.

Also in the present embodiment, the changes described in the first embodiment can be made. In addition, the method of forming the optical path conversion structure shown in this embodiment is an example, and is not necessarily limited to this formation method.

As described above, by adopting the configuration of Example 2, the light emitted from the light emitting element is guided to the optical waveguide layer and the light propagated through the optical waveguide layer is compared with the conventional configuration (see FIG. 6A). The efficiency of coupling to the light receiving element is increased, and the reliability and transmission speed of optical signal transmission are improved. Further, by using a flat substrate, a binary optical waveguide device can be manufactured with good reproducibility.

(Example 3)
FIG. 7 is a view showing a two-dimensional optical waveguide device according to Example 3. FIG. In FIG. 7, 700 is a light emitting element, 702 is a light receiving element, 704 is an incident side optical path changing structure, 706 is an outgoing side optical path changing structure, 708 is a cladding layer, and 710 is a core layer. In the light emitting element 700, the light receiving element 702, the incident side optical path conversion structure 704, and the emission side optical path conversion structure 706, the light emitted from the light emitting element 700 is optically converted by the incident side optical path conversion structure 704, and the optical path is converted. The light propagates through the core layer 810 of the two-dimensional optical waveguide, and the propagated light is optically path-converted by the exit-side optical path conversion structure 706 and coupled to the light receiving element 702. The sheet-like two-dimensional optical waveguide layer and the optical path changing structure have the same configuration as that of the above embodiment. In the present embodiment, the distance between the light receiving surface of the light receiving element 702 and the apex of the emission side optical path changing structure 706 is eliminated (the light receiving element 702 and the emission side optical path changing structure 706 are in contact), and the light emitting element 700 The core layer 810 near the incident-side optical path conversion structure 704 is made relatively thick so that the distance between the exit opening of the optical path and the apex of the incident-side optical path conversion structure 704 is at least 75 μm or more, and the output-side optical path conversion structure The core layer 810 on the 706 side is relatively thin.

  Next, a method for manufacturing the two-dimensional optical waveguide layer shown in this embodiment will be described. FIG. 8 is a schematic diagram for explaining a method of manufacturing a two-dimensional optical waveguide circuit. In the figure, 800 is a substrate, 802 is a cladding layer, 804 is an optical path changing structure material, 806 is a photomask, 808 and 810 are structures having a first shape, 812 and 814 are structures having a second shape, 816 is a reflective film material, 818 is a reflective film, 820 is a core layer, 822 is a thick core layer, 824 is a light emitting element, 826 is a light receiving element, and 928 is an element driving pad.

First, as shown in FIG. 8 (a), a polysilane resin, which is a clad layer material, is applied onto a substrate (for example, Si wafer) 800 having a uniform thickness using a spin coater and baked to form a clad having a thickness of 20 μm. Layer 802 is formed. Thereafter, as shown in FIG. 8B, a photosensitive thermoplastic material 804 that is an optical path changing structure material is applied using a spin coater, and exposed using a photomask 806. Thereafter, as shown in FIG. 8 (c), structures 808 and 810 having a radius of 25 μm, a height of 17 μm, and a cylindrical first shape are formed through a development process. In this state, as shown in FIG. 8 (d), heating is performed on a hot plate at 150 ° C. for 4 minutes, and the formed structures 808 and 810 having the first shape are melted and re-solidified by heat treatment. Then, the structures 812 and 814 having the second shape deformed into a hemisphere having a radius of 25 μm are formed. Next, as shown in FIG. 8 (e), Cr is a reflective film material 816 using an electron beam evaporation apparatus.
/ Evaporate Au. Subsequently, as shown in FIG. 8 (f), only the surfaces of the structures 812 and 814 having the second shape deformed into a hemisphere after applying a photoresist using a spin coater and undergoing an exposure / development process. A resist mask (not shown) is formed so as to cover the surface, and then etching is performed in the order of Au and Cr, and the reflective film 818 is formed only on the surfaces of the structures 812 and 814 having the second shape deformed into a hemisphere. Is done.

Subsequently, as shown in FIG. 8 (g), a polysilane resin having a refractive index larger than that of the cladding layer 802 is applied with a uniform thickness using a spin coater, and baked to form a core layer 820. Next, as shown in FIG. 8H, a thick core layer 822 is formed by etching a part of the core layer 820 using a mask having an appropriate pattern. Here, if a mask whose thickness changes gradually is formed on the core layer 820 and is etched together with the core layer, the thickness of the core layer can be gradually changed smoothly. In this way, light can be propagated with less optical loss.

Next, as shown in FIG. 8 (i), the structure 814 having the hemispherical second shape is coupled so that the emitted light from the light emitting element 824 is coupled to the structure 812 having the hemispherical second shape. The light emitting element 824 is mounted on the thick core layer 822 and the light receiving element 826 is mounted on the core layer 820 so that the propagating light coupled to the light receiving element 826 is coupled. A driving pad (Ti / Au) 828 is formed. Subsequently, as shown in FIG. 8 (j), the light emitting element 824 and the light receiving element 826 are mounted on the element driving pad 828 using a flip chip bonder to obtain a two-dimensional optical waveguide circuit.

In the two-dimensional optical waveguide circuit manufactured in this way, as shown in FIG. 9, the light emitted to the outside can be reduced compared to the conventional one, so that the transmission efficiency of the optical signal is increased. (Figure 9 (a) shows the conventional one,
FIG. 9 (b) shows this example). Further, light incident from the upper surface of the hemispherical structure 812 is efficiently scattered and propagated throughout the core layer 820. The light propagating through the core layer 820 is scattered by the structure 814 having the second shape deformed into a hemispherical shape, and is emitted upward of the hemispherical structure 814.

Also in the present embodiment, the changes described in the first embodiment can be made. Further, the method for forming the core layer shown in this embodiment is an example, and is not necessarily limited to this method. In this embodiment, the thick core layer 822 is formed by etching the core layer 820, but may be formed by the method shown in FIG.

In this method, first, as shown in FIG. 10 (a), the core layer 1000 is formed using a polysilane resin having photosensitivity. The steps up to the formation of the core layer 1000 are the same as those in FIG. Subsequently, as shown in FIG. 10B, a photosensitive polysilane-based resin 1002 on which the core layer 1000 is formed is applied using a spin coater. Next, as shown in FIG. 10C, the polysilane resin 1002 having photosensitivity is exposed using a photomask 1004. Thereafter, a thick core layer 1006 is formed by performing a developing process as shown in FIG. Here, the thickness of the resin core layer can be gradually and smoothly changed by exposing and developing the photosensitive resin as the core layer with gradation using a photomask having gradation.

As described above, the configuration of Example 3 allows the light emitted from the light emitting element to be guided to the optical waveguide layer and to propagate the light through the optical waveguide layer, compared to the conventional configuration (see FIG. 9A). The efficiency of coupling to the light receiving element is increased, and the reliability and transmission speed of optical signal transmission are improved. In addition, since the structure of this example is always processed on a flat surface, it is easier to produce a two-dimensional optical waveguide circuit than in Example 1 or Example 2, and it can be produced with good reproducibility.

(Example 4)
FIG. 11 shows a photoelectric fusion substrate of Example 4 manufactured by combining the two-dimensional optical waveguide circuit shown in Examples 1 to 3 and an electric circuit substrate. In FIG. 11, 1100 is a CPU, 1102, 1104, 1106 and 1108 are RAMs, 1110 and 1112 are electronic devices (LSIs), 1114 is a light emitting element, 1116 is a light receiving element, 1118 is a transmission line (electrical wiring), 1120 is a beam light , 1122 are diffused light, 1124 is a two-dimensional optical waveguide layer of the present invention, and 1126 and 1128 are electric circuit boards. FIG. 11 (a) is a view of the optoelectronic substrate of FIG. 11 (b) as viewed from the direction of the arrow. In FIG. 11 (a), the two-dimensional optical waveguide layer 1124 and the electric circuit substrate 1128 are not shown.

FIG. 12 is a cross-sectional view of a part of the photoelectric fusion substrate. The CPU 1200 is flip-chip bonded on the electric circuit board 1202 using solder balls 1204. Connection between the CPU 1200 and the light emitting element 1208 mounted on the two-dimensional optical waveguide layer 1206 is made through an internal wiring 1210 formed on the electric circuit board 1202.

With conventional electrical wiring boards, there is no problem with low-speed data transfer, but when high-capacity and high-speed transmission is required, stable data transfer is always possible due to the effects of EMI and wiring delays. Can be difficult. In such a case, stable large-capacity and high-speed transmission is possible by using a photoelectric fusion substrate as shown in FIG. For example, a signal transmission method will be described in which an electrical signal from a CPU is converted into an optical signal via a light emitting element and the signal is transmitted to a light receiver electrically connected to a RAM or LSI. As shown in FIG. 11, the light emitting element 1114 electrically connected to the CPU 1100 is embedded in the two-dimensional optical waveguide layer, and the laser beam emitted from the light emitting element 1114 is an optical path conversion structure (not shown). And propagates in the two-dimensional optical waveguide layer 1124.

In FIG. 11, a 1 × 2 surface-emitting laser array is used as the light-emitting element 1114, and by controlling the injection current of each surface-emitting laser, the beam light propagation having the directivity or the propagation of the diffused light, or the both propagations are performed. Can be selected. The laser light propagating through the two-dimensional optical waveguide layer 1124 in this way is coupled to an optical path conversion structure (not shown) provided near the light receiving element 1116 and guided to the light receiving element 1116. The light receiving element 1116 is connected to each RAM or LSI, and converts an optical signal into an electric signal. In FIG. 11, a high-speed signal is transmitted to the RAM 1102 by propagation of the beam light 1120, and is simultaneously transmitted to the three RAMs as propagation of the diffused light 1122 to the RAM 1104, RAM 1106, and RAM 1108. Although not shown, by controlling the injection current, the spread angle of the diffused light propagation can be further widened, and the signal can be transmitted to the LSI 1110 and the LSI 1112.

In this embodiment, a 1 × 2 surface emitting laser array is used, but the present invention is not limited to this, and an array of more surface emitting lasers or a single surface emitting laser may be used. In the present embodiment, the two-dimensional optical waveguide layer is built in between the electric circuit boards. However, the present invention is not limited to this, and there is a form in which the two-dimensional optical waveguide layer is provided on the upper or lower part of the electric circuit board. , Or a combination of each. The two-dimensional optical waveguide layer is a single layer, but may be a multilayer. Note that the signal does not necessarily have to be transmitted by light, and selection flexibility is provided so that the signal can also be transmitted through the electrical wiring 1018.

By using the two-dimensional optical waveguide layer in this way, the electromagnetic radiation noise that caused the malfunction of the circuit due to common mode noise radiation etc. can be greatly reduced by the wiring itself that has become a problem with conventional signal lines becoming an antenna, EMI problem can be improved.

In addition, by controlling the injection current to each surface emitting laser, it is possible to select either light beam propagation or diffused light propagation. In light beam propagation, optical power loss is suppressed and high-speed transmission is possible. Thus, in diffused light propagation, the spread angle of diffused light propagation can be changed by changing the injection current, and the optical signal transmission region can be reconfigured.

1 is a cross-sectional view illustrating a two-dimensional optical waveguide circuit according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a method for manufacturing a two-dimensional optical waveguide circuit in the first example of the present invention. FIG. 6 is a cross-sectional view illustrating a comparison between a conventional example and a two-dimensional optical waveguide circuit in the first example of the present invention. FIG. 6 is a cross-sectional view illustrating a two-dimensional optical waveguide circuit according to a second embodiment of the present invention. FIG. 10 is a cross-sectional view illustrating a method for manufacturing a two-dimensional optical waveguide circuit in a second example of the present invention. FIG. 6 is a cross-sectional view illustrating a comparison between a conventional example and a two-dimensional optical waveguide circuit in a second example of the present invention. FIG. 10 is a cross-sectional view illustrating a two-dimensional optical waveguide circuit in a third example of the present invention. FIG. 10 is a cross-sectional view illustrating a method for manufacturing a two-dimensional optical waveguide circuit in a third example of the present invention. FIG. 10 is a cross-sectional view illustrating a comparison between a conventional example and a two-dimensional optical waveguide circuit in a third example of the present invention. FIG. 10 is a cross-sectional view for explaining a part of the manufacturing method of the two-dimensional optical waveguide circuit in the third embodiment of the present invention. FIG. 10 is a diagram for explaining an optoelectronic interconnection board in a fourth embodiment of the present invention. FIG. 10 is a cross-sectional view illustrating the inside of a photoelectric fusion wiring board in a fourth embodiment of the present invention.

Explanation of symbols

100, 218, 400, 522, 700, 824, 1114, 1208: Light emitting element
102, 220, 402, 524, 702, 826, 1116: Light receiving element
104, 404, 704: Incident side optical path conversion structure
106, 406, 706: Output side optical path conversion structure
108, 202, 408, 502, 708, 802: Clad layer
110, 216, 410, 520, 710, 820, 1000: Core layer

Claims (3)

A two-dimensional optical waveguide device including at least a sheet-shaped core layer, wherein a structure for optical path conversion is disposed in the vicinity of a position where a light emitting element and a light receiving element are to be disposed;
The height of the optical path changing structure disposed in the vicinity of the light emitting element is substantially the same as the height of the optical path converting structure disposed in the vicinity of the light receiving element, and the portion where the light emitting element is to be disposed. thickest of Turkey a layer be correspondingly thicker than the thickness of Turkey a layer to correspond to locations to be arranged in the light receiving element, and the structure of the optical path conversion disposed near the light receiving element A two-dimensional optical waveguide device characterized in that an upper portion and a light receiving surface of the light receiving element are in contact with each other . Two-dimensional optical waveguide device according to claim 1, wherein the thickness of the core layer is gradually changed. An optoelectronic interconnection substrate, wherein the two-dimensional optical waveguide device according to claim 1 or 2 is formed so as to be electrically connected to an electric circuit substrate, wherein a part or all of the signals of the electric circuit substrate are An optoelectronic wiring board, wherein wiring is performed by transmission and reception of an optical signal using a two-dimensional optical waveguide device.