JP7321907B2 - Optical waveguide, optical waveguide device, and method for manufacturing optical waveguide - Google Patents

Description

The present invention relates to an optical waveguide, an optical waveguide device, and a method for manufacturing an optical waveguide.

2. Description of the Related Art Conventionally, there has been known an optical waveguide device in which an optical waveguide for handling optical signals is formed on a wiring substrate for handling electrical signals (see, for example, Patent Document 1). An optical waveguide device is an opto-electric composite substrate, and in order to compensate for the limitation of the transmission speed of electrical signals, the high-speed part can be transmitted by optical signals.

As shown in FIG. 25 , in the optical waveguide device 100 , an optical signal is transmitted through an optical waveguide 110 having a structure in which a core layer 112 is surrounded by a clad layer 111 . An optical element (not shown) is mounted on the clad layer 111 of the optical waveguide 110 so as to be optically coupled to the optical path conversion mirror 115 of the optical waveguide 110 .

Next, an example of a method for manufacturing the optical waveguide 110 of the optical waveguide device 100 will be described.
As shown in FIG. 26A, first, a lower clad layer 111A, a core layer 112 and an upper clad layer 111B are sequentially formed on a substrate 130. Then, as shown in FIG. Subsequently, grooves 113 are formed so as to divide the core layer 112 from the upper cladding layer 111B side by a rotating blade of a cutting device. At this time, the groove portion 113 has an inclined surface 114 inclined at a predetermined angle with respect to the extending direction of the core layer 112 . Further, as shown in FIG. 26B, the groove portion 113 is formed so as to extend over the entire length of the plurality of core layers 112 arranged in the vertical direction (Y-axis direction) in the figure. A plurality of core layers 112 are collectively divided by the grooves 113 . Next, as shown in FIG. 27A, a mask 140 having openings 140X corresponding to the grooves 113 is formed. Next, a mask 140 is used to selectively deposit a lustrous metal film on the inclined surface 114 of the groove 113 to form the optical path conversion mirror 115 on the inclined surface 114 . After that, by removing the mask 140, the optical waveguide 110 can be manufactured on the substrate 130 as shown in FIG. 27(b).

JP 2013-257381 A

By the way, in the conventional optical waveguide device 100, as shown in FIG. 25, the groove portion 113 is formed so as to extend over the entire length of the substrate 130 in the vertical direction (Y-axis direction) in the drawing. There is a problem that the degree of freedom in designing the optical waveguide 110 is reduced by such grooves 113 .

According to one aspect of the present invention, a first clad layer, a plurality of core layers formed on the upper surface of the first clad layer, and a plurality of core layers formed on the upper surface of the first clad layer so as to cover the core layers a second clad layer; a plurality of grooves provided corresponding to each of the plurality of core layers; and an inclined surface provided in each groove and inclined at a predetermined angle with respect to the extending direction of each core layer, and an optical path conversion mirror formed on the inclined surface, wherein the plurality of grooves are , are formed apart from each other, the inclined surfaces are formed only on the first clad layer and the second clad layer, the optical path conversion mirror is not in contact with the core layer, and the The second clad layer is provided apart from the core layer, and the second clad layer is formed so as to cover only an end surface of the core layer in the extending direction of the core layer, and the grooves are provided in the core layers. and the second clad layer covering the end face of the core layer in the extending direction is provided between the end face of the core layer in the extending direction and the groove part. .

According to one aspect of the present invention, there is an effect that the degree of freedom in design can be improved.

FIG. 2 is a schematic cross-sectional view showing the optical waveguide device of the first embodiment (cross-sectional view along line 1-1 in FIG. 2); 1 is a schematic plan view showing an optical waveguide device according to a first embodiment; FIG. 1 is a perspective sectional view showing an optical waveguide device according to a first embodiment; FIG. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 1st Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 1st Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 1st Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 1st Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 1st Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 1st Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 1st Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 2nd Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 2nd Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 2nd Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 2nd Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 2nd Embodiment. FIG. 17 is a schematic cross-sectional view showing the optical waveguide device of the third embodiment (cross-sectional view taken along line 16-16 in FIG. 17); The schematic plan view which shows the optical waveguide apparatus of 3rd Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 3rd Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 3rd Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 3rd Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 3rd Embodiment. (a), (b) is a schematic sectional drawing which shows the manufacturing method of the optical waveguide device of 3rd Embodiment. FIG. 4 is a schematic cross-sectional view showing an optical waveguide device of a modified example; FIG. 4 is a schematic cross-sectional view showing an optical waveguide device of a modified example; FIG. 2 is a schematic plan view showing a conventional optical waveguide device; (a) is a schematic cross-sectional view showing a conventional method for manufacturing an optical waveguide device, and (b) is a schematic plan view showing a conventional method for manufacturing an optical waveguide device. (a) and (b) are schematic cross-sectional views showing a method of manufacturing a conventional optical waveguide device.

Each embodiment will be described below with reference to the accompanying drawings. In the accompanying drawings, characteristic portions may be enlarged for convenience and to make the characteristics easier to understand, and the dimensional ratios of the constituent elements may differ from one drawing to another. Also, in the cross-sectional views, in order to make the cross-sectional structure of each member easier to understand, the hatching of some members is shown instead of the satin pattern, and the hatching of some members is omitted. In the following description, the left-right direction in FIG. 1 is called the X-axis direction, the up-down direction in FIG. 1 is called the Z-axis direction, and the direction perpendicular to the plane of FIG. 1 is called the Y-axis direction. As used herein, the term “planar view” refers to viewing an object from the Z-axis direction (for example, the vertical direction), and the term “planar shape” refers to the shape of the object viewed from the Z-axis direction. To tell. In addition, "parallel", "perpendicular" and "horizontal" in this specification are not limited to strictly parallel, perpendicular and horizontal, but generally parallel, perpendicular and horizontal within the range where the effects of the present embodiment are exhibited. case is also included.

(First embodiment)
The first embodiment will be described below with reference to FIGS. 1 to 10. FIG.
As shown in FIG. 1 , the optical waveguide device 10 has a wiring substrate 20 , an optical waveguide 30 formed on the wiring substrate 20 , and an optical element 50 . As the optical element 50, for example, a light emitting element such as a vertical cavity surface emitting laser (VCSEL) or a light emitting diode (LED) can be used. As the optical element 50, for example, a light receiving element such as a photodiode (PD) or an avalanche photodiode (APD) can be used.

The wiring board 20 has a board body 21 , a wiring pattern 22 on the uppermost layer, a wiring pattern 23 on the lowermost layer, and a solder resist layer 24 .
It is sufficient for the substrate body 21 to have a structure in which the wiring patterns 22 and 23 are formed on the outermost layer and the wiring patterns 22 and 23 are electrically connected to each other through the inside of the substrate. Therefore, the wiring layer may be formed inside the substrate body 21, and the wiring layer may not be formed. When a wiring layer is formed inside the substrate main body 21, a plurality of wiring layers are laminated via interlayer insulating layers, and the wiring pattern 22 is formed by each wiring layer and vias formed in each interlayer insulating layer. , 23 are electrically connected to each other. As the substrate main body 21, for example, a build-up substrate with a core having a core substrate, a coreless substrate having no core substrate, or the like can be used.

The wiring pattern 22 is provided on the upper surface of the substrate body 21 . The wiring pattern 22 has connection pads P<b>1 electrically connected to the electrode terminals 51 of the optical element 50 . The thickness of the wiring pattern 22 can be, for example, about 15 μm to 35 μm. As a material of the wiring pattern 22, for example, copper (Cu) or a copper alloy can be used.

The wiring pattern 23 is provided on the bottom surface of the substrate body 21 . The wiring pattern 23 has an external connection pad P2. The thickness of the wiring pattern 23 can be, for example, about 15 μm to 35 μm. As a material of the wiring pattern 23, for example, copper or a copper alloy can be used.

The solder resist layer 24 is formed on the lower surface of the substrate body 21 so as to cover the wiring pattern 23 . The solder resist layer 24 is formed with an opening 24X for exposing a portion of the wiring pattern 23 as the external connection pad P2. The external connection pads P2 are connected to external connection terminals such as solder balls and lead pins that are used when the wiring board 20 is mounted on a motherboard or the like. If necessary, an OSP (Organic Solderability Preservative) process may be performed on the wiring pattern 23 exposed from the opening 24X to form an OSP film, and an external connection terminal may be connected to the OSP film. Alternatively, a metal layer may be formed on the wiring pattern 23 exposed from the opening 24X, and the external connection terminal may be connected to the metal layer. Examples of metal layers include a gold (Au) layer, a nickel (Ni)/Au layer (a metal layer in which a Ni layer and an Au layer are laminated in this order), and a Ni/palladium (Pd)/Au layer (Ni layer, a Pd layer, and an Au layer laminated in this order). Here, the Au layer is a metal layer made of Au or an Au alloy, the Ni layer is a metal layer made of Ni or a Ni alloy, and the Pd layer is a metal layer made of Pd or a Pd alloy. As these Ni layer, Au layer, and Pd layer, for example, a metal layer (electroless plated metal layer) formed by an electroless plating method can be used. Further, when the wiring pattern 23 itself exposed from the opening 24X or an OSP film or a metal layer is formed on the wiring pattern 23, the OSP film or the metal layer itself may be used as an external connection terminal.

The planar shapes of the openings 24X and the external connection pads P2 can be arbitrary shapes and arbitrary sizes. For example, the planar shape of the opening 24X and the external connection pad P2 can be circular with a diameter of about 200 μm to 300 μm. The thickness from the lower surface of the substrate body 21 to the lower surface of the solder resist layer 24 can be, for example, approximately 20 μm to 40 μm. As the material of the solder resist layer 24, for example, an epoxy-based or acrylic-based insulating resin can be used.

The optical waveguide 30 is formed on the upper surface of the substrate body 21 of the wiring substrate 20 . The optical waveguide 30 has a clad layer 31 , a core layer 32 , a clad layer 33 and a clad layer 34 .

The cladding layer 31 is formed on the upper surface of the substrate body 21 . The clad layer 31 is formed, for example, on the upper surface of the substrate body 21 so as to cover the wiring pattern 22 . One or more core layers 32 are formed on the upper surface of the clad layer 31 .

As shown in FIG. 2, two core layers 32 are formed on the upper surface of the clad layer 31 of this embodiment. Each core layer 32 is for propagating an optical signal. Each core layer 32 is formed, for example, in an elongated shape. Each core layer 32 is formed, for example, to extend in the X-axis direction. That is, the extension direction of each core layer 32 of this embodiment matches the X-axis direction. Each core layer 32 is formed in, for example, a quadrangular prism shape. A plurality of core layers 32 are provided side by side along the Y-axis direction orthogonal to the extending direction of the core layers 32 . The multiple core layers 32 are formed, for example, to extend in parallel. 2 is a top plan view of the optical waveguide device 10 shown in FIG. 1, in which the cladding layer 34, the optical element 50, and the like are depicted transparently.

As shown in FIG. 1 , the clad layer 33 is formed on the upper surface of the clad layer 31 . The clad layer 33 is formed so as to fill the space between adjacent core layers 32 . The clad layer 33 is formed to cover the entire side surface of each core layer 32 . The clad layer 33 is formed, for example, so as to cover the entire upper surface of the core layer 32 .

One or more (here, two) grooves 35 are formed in the clad layers 31 and 33 . Each groove 35 is provided corresponding to each core layer 32 . Each groove 35 is formed, for example, so as to extend from the upper surface of the clad layer 33 halfway in the thickness direction (Z-axis direction) of the clad layer 31 . Each groove 35 has, for example, an inclined surface 36 for converting the optical path by 90 degrees. The inclined surface 36 is formed, for example, at a predetermined angle (for example, 45 degrees) with respect to the extension direction (X-axis direction) of the core layer 32 . That is, the inclined surface 36 is formed at an angle of 45 degrees with respect to the propagation direction (advancing direction) of the light propagating through the core layer 32 . The cross-sectional shape of the groove portion 35 is, for example, a substantially right-angled triangular shape.

The inclined surface 36 is formed, for example, so as to extend from the upper surface of the clad layer 33 halfway in the thickness direction of the clad layer 31 . The inclined surface 36 is formed only on the clad layers 31 and 33, for example. In other words, the inclined surface 36 is not formed in the core layer 32 . The inclined surface 36 is provided apart from the core layer 32, for example. The inclined surface 36 is provided apart from the end surface 32A in the extending direction of the core layer 32 in the X-axis direction. That is, the inclined surface 36 does not contact the core layer 32 . However, the inclined surface 36 is formed on an extension of the central axis of the core layer 32 in the X-axis direction. The inclined surface 36 is formed so as to face the end surface 32A of the core layer 32 in the X-axis direction. Here, the term “opposing” in this specification refers to the fact that the surfaces or members are in front of each other, not only when they are completely in front of each other, but also when they are partially in front of each other. Including when in position. In addition, the term "opposing" in this specification means both the case where a member different from the two parts is interposed between the two parts and the case where nothing is interposed between the two parts. including.

As shown in FIG. 2, the plurality of grooves 35 are provided apart from each other in the Y-axis direction. That is, the plurality of grooves 35 are provided at predetermined intervals in the Y-axis direction.

The planar shape of each groove portion 35 (inclined surface 36) is, for example, a square shape. The planar shape of each groove portion 35 is, for example, a trapezoidal shape in which the lengths of the upper base and the lower base are different from each other. Each groove 35 is formed, for example, so that the opening width (that is, the opening width along the Y-axis direction) becomes narrower as it approaches the core layer 32 from the farthest end from the core layer 32 in the X-axis direction. ing. The opening width of each groove 35 is, for example, set wider than the dimension of the core layer 32 along the Y-axis direction (that is, the width dimension).

As shown in FIG. 3, the inclined surface 36 has, for example, a rectangular front shape when viewed from the X-axis direction (the central axis of the core layer 32). The front shape of the inclined surface 36 is, for example, a trapezoidal shape in which the lengths of the upper base and the lower base are different from each other. The inclined surface 36 is formed, for example, so that the dimension along the Y-axis direction (that is, the width dimension) decreases from the upper end to the lower end. That is, the inclined surface 36 is formed such that the width dimension thereof decreases from the upper surface side of the clad layer 33 toward the lower surface side of the clad layer 31 .

Each inclined surface 36 is formed with an optical path conversion mirror 37 for converting the optical path by 90 degrees. That is, the optical waveguide 30 is provided with a plurality of (here, two) optical path conversion mirrors 37 . As shown in FIG. 2, the plurality of optical path conversion mirrors 37 are provided, for example, apart from each other in the Y-axis direction. That is, the plurality of optical path conversion mirrors 37 are provided at predetermined intervals in the Y-axis direction. As a material of the optical path conversion mirror 37, for example, a metal material having good light reflectivity can be used. As the material of the optical path conversion mirror 37, for example, metal materials such as gold, silver (Ag), and aluminum (Al) can be used.

As shown in FIG. 3 , each optical path conversion mirror 37 is formed, for example, so as to cover the inclined surface 36 . Each optical path conversion mirror 37 is formed, for example, so as to cover the entire upper portion of the inclined surface 36 . Each optical path conversion mirror 37 is formed, for example, so as to cover the upper portion of the inclined surface 36 over the entire length in the Y-axis direction. Each optical path conversion mirror 37 is formed, for example, so as to expose the lower portion of the inclined surface 36 . That is, the lower portion of the inclined surface 36 is exposed from the optical path conversion mirror 37 . Each optical path conversion mirror 37 is formed, for example, so as to protrude below the lower surface of the core layer 32 and the upper surface of the clad layer 31 . Each optical path conversion mirror 37 is formed, for example, to protrude above the upper surface of the core layer 32 . The upper end surface of each optical path conversion mirror 37 is formed so as to be flush with the upper surface of the clad layer 33, for example.

Each optical path conversion mirror 37 is provided apart from the core layer 32, for example. Each optical path conversion mirror 37 is provided apart from the end face 32A in the extending direction of the core layer 32 in the X-axis direction. That is, each optical path conversion mirror 37 is not in contact with the core layer 32 . However, each optical path conversion mirror 37 is formed on an extension of the central axis of the core layer 32 in the X-axis direction. Each optical path conversion mirror 37 is formed to face the end surface 32A of the core layer 32 in the X-axis direction.

Each optical path conversion mirror 37 is formed only on the inclined surface 36, for example. In other words, each optical path conversion mirror 37 is not formed on the upper surface of the clad layer 33 or the upper surface of the core layer 32 . Each optical path conversion mirror 37 is formed flat on the inclined surface 36, for example. For example, each optical path conversion mirror 37 is formed in a flat shape without steps. For example, each optical path conversion mirror 37 is formed in a thin plate shape without steps.

The planar shape of each optical path conversion mirror 37 is formed, for example, in a shape along the planar shape of the inclined surface 36 . The planar shape of each optical path conversion mirror 37 is, for example, rectangular. The planar shape of each optical path conversion mirror 37 is, for example, a trapezoidal shape in which the lengths of the upper base and the lower base are different from each other. For example, in the X-axis direction, each optical path conversion mirror 37 has a dimension (that is, a width dimension) along the Y-axis direction from an upper end portion farthest from the core layer 32 toward a lower end portion closer to the core layer 32. designed to be short. The width dimension of each optical path conversion mirror 37 is set wider than the width dimension of the core layer 32, for example.

As shown in FIG. 1, the clad layers 31, 33 and the core layer 32 are formed with openings 38 penetrating through the clad layers 31, 32 and 33 in the thickness direction. The opening 38 is provided corresponding to each core layer 32, for example. The opening 38 is provided, for example, between the end face 32A of the core layer 32 and the groove 35 in the X-axis direction. The opening 38 is formed, for example, so as to communicate with the groove 35 . The opening 38 is formed, for example, so as to expose the end surface 32A of the core layer 32 . The opening 38 is formed, for example, so as to expose part of the upper surface of the wiring pattern 22 .

The inner wall surface of the opening 38 is formed, for example, so as to rise vertically from the upper surface of the wiring pattern 22 . For example, the end face 32A of the core layer 32 is formed in a vertical plane extending perpendicularly to the direction in which the core layer 32 extends. The end surface 32A of the core layer 32 is formed flush with the inner wall surface of the opening 38 formed by the clad layers 31 and 33, for example. The inner wall surface of the opening 38 may be formed as an inclined surface inclined at a predetermined angle with respect to the extension direction of the core layer 32 .

As shown in FIG. 2, the planar shape of the opening 38 can be any shape and any size. The planar shape of the opening 38 is, for example, a square shape. The opening width of the opening 38 along the Y-axis direction is, for example, wider than the width dimension of the core layer 32 .

As shown in FIG. 1, the clad layer 34 is formed to cover the upper surface of the clad layer 33, for example. The cladding layer 34 is formed, for example, so as to fill the groove 35 and the opening 38 . The clad layer 34 is formed, for example, so as to cover the optical path conversion mirror 37 . The clad layer 34 is formed, for example, so as to cover the entire surface of the optical path conversion mirror 37 exposed from the clad layers 31 and 33 . As a result, the entire surface of the optical path conversion mirror 37 is covered with the clad layers 31 , 33 and 34 . That is, the optical path conversion mirror 37 is covered only with the cladding layers 31 , 33 , 34 . In other words, the optical path conversion mirror 37 is embedded in the clad layers 31 , 33 and 34 .

The clad layer 34 is formed, for example, so as to cover the end surface 32A of the core layer 32 . Thus, the optical waveguide 30 has a structure in which the cladding layer 31, the core layer 32, the cladding layer 33, and the cladding layer 34 are laminated in this order on the upper surface of the substrate body 21, and the core layer 32 is the cladding layer. 31, a clad layer 33, and a clad layer .

Basically, the same materials can be used as materials for the clad layers 31, 33, 34 and the core layer 32. As shown in FIG. For example, as materials for the clad layers 31, 33, 34 and the core layer 32, a resin material having optical transparency in the wavelength range used by the optical element 50 can be used. Specifically, as materials for the clad layers 31, 33, 34 and the core layer 32, acrylic resins such as polymethyl methacrylate (PMMA), epoxy resins, silicone resins, and the like can be used. However, in order to allow the optical signal to propagate only within the core layer 32, the material constituting the core layer 32 is the clad layers 31, 33, and 34 formed on both upper and lower surfaces of the core layer 32. A material with a higher refractive index than the constituent material is selected. The difference in refractive index between the core layer 32 and the clad layers 31, 33, and 34 is not particularly limited, but is preferably about 0.3% to 5.5%, more preferably 0.8% to 2.2%. degree is more preferred.

The thickness of the clad layer 31, specifically, the thickness from the upper surface of the wiring pattern 22 to the upper surface of the clad layer 31 can be, for example, about 10 μm to 15 μm. The thickness of the core layer 32, specifically, the thickness from the upper surface of the clad layer 31 to the upper surface of the core layer 32 can be, for example, approximately 30 μm to 80 μm. The width dimension of the core layer 32 can be, for example, about 20 μm to 50 μm. The pitch of the core layers 32 can be, for example, about 100 μm to 300 μm. The thickness of the clad layer 33, specifically, the thickness from the upper surface of the clad layer 31 to the upper surface of the clad layer 33 can be, for example, approximately 30 μm to 100 μm. The thickness of the clad layer 34, specifically, the thickness from the upper surface of the clad layer 33 to the upper surface of the clad layer 34 can be, for example, approximately 30 μm to 80 μm.

In FIG. 1, the clad layers 31, 33, and 34 are distinguished by solid lines for easy understanding. For example, in the optical waveguide 30, the interfaces between the clad layers 31, 33, and 34 may disappear, and the boundaries may not be clear.

As shown in FIG. 1, the optical waveguide 30 is formed with an opening 30X for exposing a portion of the wiring pattern 22 as a connection pad P1. The openings 30X are provided at positions corresponding to the electrode terminals 51 of the optical element 50 . The opening 30X is provided, for example, at a position away from the optical path conversion mirror 37 in the direction away from the core layer 32 . The opening 30X is formed, for example, so as to penetrate the clad layers 31, 33, 34 in the thickness direction. The opening 30X is, for example, tapered such that the opening width (opening diameter) decreases from the upper side (the upper surface side of the cladding layer 34) toward the lower side (the wiring pattern 22 side) in FIG. For example, the opening 30X is formed in an inverted truncated cone shape in which the opening diameter of the lower opening end is smaller than the opening diameter of the upper opening end.

Solders 40 are formed on the connection pads P1 to electrically connect the connection pads P1 and the electrode terminals 51 of the optical element 50 . As the material of the solder 40, for example, an alloy containing lead (Pb), an alloy of tin (Sn) and Cu, an alloy of Sn and Ag, an alloy of Sn, Ag and Cu, or the like can be used.

If necessary, the wiring pattern 22 exposed from the opening 30X may be subjected to an OSP process to form an OSP film, and the solder 40 may be formed on the OSP film. Alternatively, a metal layer may be formed on the wiring pattern 22 exposed from the opening 30X, and the solder 40 may be formed on the metal layer. Examples of metal layers include Au layers, Ni/Au layers, and Ni/Pd/Au layers.

As shown in FIG. 2 , two openings 30X are formed in each core layer 32 in the optical waveguide 30 . The plurality of openings 30X are provided side by side along the Y-axis direction, for example. The plurality of openings 30X are provided, for example, at predetermined intervals in the Y-axis direction. Each opening 30X is provided, for example, at a position not overlapping the groove 35 in the X-axis direction. That is, the one groove 35 and the two openings 30X are provided at different positions in the Y-axis direction. For example, one groove 35 and two openings 30X are alternately provided. For example, the groove 35 is provided between the two openings 30X in the Y-axis direction.

As shown in FIG. 1, the optical element 50 has, for example, two electrode terminals 51 and one light emitting/receiving section 52 . As for the two electrode terminals 51, for example, one electrode terminal 51 is connected to a cathode electrode (not shown) within the optical element 50, and the other electrode terminal 51 is connected to an anode electrode (not shown) within the optical element 50. It is As each electrode terminal 51, for example, a metal column, a gold bump, or a solder bump can be used. As a material for the metal pillars, for example, copper or a copper alloy can be used. As the material of the solder bumps, for example, an alloy containing Pb, an alloy of Sn and Cu, an alloy of Sn and Ag, an alloy of Sn, Ag and Cu, or the like can be used.

The light receiving/emitting part 52 becomes a light emitting part when the optical element 50 is a light emitting element, and becomes a light receiving part when the optical element 50 is a light receiving element. For example, the plane center of the light emitting/receiving section 52 is the optical axis center A1 of the optical element 50 . The optical axis center A1 is, for example, the light emitting point when the optical element 50 is a light emitting element, and the center point of the light receiving area when the optical element 50 is a light receiving element.

The optical element 50 is mounted on the wiring substrate 20 on which the optical waveguide 30 is laminated (integrated). For example, the electrode terminals 51 of the optical element 50 are inserted into the openings 30X, and are electrically connected to the connection pads P1 of the wiring board 20 via the electrode terminals 51 and the solder 40 . Thereby, each optical element 50 is electrically connected to the wiring pattern 22 of the wiring board 20 via the electrode terminal 51 and the solder 40 . That is, each optical element 50 is flip-chip mounted on the wiring board 20 . At this time, the optical element 50 is mounted on the wiring board 20 so that the light emitting/receiving section 52 faces the optical path conversion mirror 37 . The optical element 50 is mounted on the wiring board 20 so that the light emitting/receiving section 52 is arranged right above the optical path conversion mirror 37, for example. Specifically, the optical element 50 is mounted on the wiring board 20 so that the optical axis center A1 overlaps a predetermined position of the optical path conversion mirror 37 (for example, the center of the inclined surface of the optical path conversion mirror 37) in plan view. there is In other words, the opening 30X is formed at a position where the electrode terminal 51 of the optical element 50 can be inserted while the optical axis center A1 and the predetermined position of the optical path conversion mirror 37 are aligned.

An underfill resin 60 is formed between the optical element 50 and the optical waveguide 30 and wiring board 20 . The underfill resin 60 is formed, for example, so as to fill the gap between the upper surface of the clad layer 34 and the lower surface of the optical element 50 . The underfill resin 60 is formed, for example, to fill the opening 30X. The underfill resin 60 is a resin for improving the connection strength of the connection portions between the electrode terminals 51 of the optical element 50 and the connection pads P1 of the wiring board 20 . As the material of the underfill resin 60, for example, a resin material having optical transparency in the wavelength range used by the optical element 50 can be used. As the material of the underfill resin 60, for example, the same resin material as that of the clad layers 31, 33, and 34 can be preferably used.

When the optical element 50 is a light emitting element, the light emitted from the optical axis center A1 (light emitting point) of the light emitting/receiving portion 52, which is the light emitting portion, passes through the groove portion 35 of the optical waveguide 30 as indicated by the arrow in the drawing. is incident on The light incident on the groove 35 is formed on the inclined surface 36 and is incident on the core layer 32 of the optical waveguide 30 after the optical path is bent 90 degrees by the optical path conversion mirror 37 . Light incident on the core layer 32 is propagated through repeated total reflection within the core layer 32 . On the other hand, when the optical element 50 is a light-receiving element, the light propagating through the core layer 32 of the optical waveguide 30 is reflected by the optical path conversion mirror 37 and emitted from the groove 35 of the optical waveguide 30 to reach the light-receiving portion. is incident on the optical axis center A1 of the light emitting/receiving portion 52.

(Manufacturing method of optical waveguide device 10)
Next, a method for manufacturing the optical waveguide device 10 will be described. For convenience of explanation, the parts that will eventually become the components of the optical waveguide device 10 will be described with the reference numerals of the final components.

First, in the process shown in FIG. 4A, the wiring board 20 is prepared. First, the wiring patterns 22 and 23 patterned into a desired shape are formed on both surfaces of the substrate body 21 . Subsequently, a solder resist layer 24 having openings 24X exposing a portion of the wiring pattern 23 as external connection pads P2 is formed on the lower surface of the substrate body 21 . The solder-resist layer 24 is formed by, for example, forming the solder-resist layer 24 on the lower surface of the substrate body 21 so as to cover the wiring pattern 23, and then exposing and developing the solder-resist layer 24 by photolithography to form the openings 24X. .

It should be noted that, if necessary, a metal layer, for example, a Ni layer and an Au layer laminated in this order, may be formed on the external connection pad P2. The metal layer can be formed, for example, by electroless plating.

Next, the optical waveguide 30 is laminated on the upper surface of the wiring board 20 according to FIGS. 4(b) to 8(b).
First, in the step shown in FIG. 4B, the clad layer 31 is formed on the upper surface of the substrate body 21 so as to cover the wiring pattern 22 . For example, a photosensitive resin layer (not shown) to be the cladding layer 31 is formed on the entire upper surface of the substrate body 21, exposed and developed based on photolithography, and then cured by curing the photosensitive resin layer. A clad layer 31 is formed. As a method for forming the photosensitive resin layer, for example, a liquid photosensitive resin may be applied to the entire upper surface of the substrate body 21 , or a semi-cured photosensitive resin sheet may be applied to the entire upper surface of the substrate body 21 . You may make it laminate. Here, as the photosensitive resin, for example, an ultraviolet (UV) curable resin can be preferably used. As the UV curable resin, for example, a resin material containing a modified acrylate (epoxy resin, polyester resin, etc.) as a base resin, a reactive acrylic monomer required for photopolymerization, a photopolymerization initiator, and additives can be used. . The main reaction of such UV curable resins is radical polymerization. By using such a UV curable resin, processing can be performed at room temperature, and furthermore, the work time can be shortened because the resin can be cured in a shorter time than when a thermosetting resin is used. The materials of the photosensitive resin layer are the same in the process of forming the core layer 32 and the clad layers 33 and 34, which will be described later.

Subsequently, in the step shown in FIG. 5A, a plurality of core layers 32 are formed on the upper surface of the cladding layer 31 . For example, a photosensitive resin layer (not shown) serving as the core layer 32 is formed on the entire upper surface of the cladding layer 31, exposed and developed based on photolithography, and then cured by curing the photosensitive resin layer. A core layer 32 is formed. Through this step, a strip-shaped core layer 32 is formed on the upper surface of the clad layer 31 .

Next, in the step shown in FIG. 5B, a clad layer 33 is formed on the top surface of the clad layer 31 to cover the entire side surfaces of the plurality of core layers 32 . The clad layer 33 of this embodiment is formed to cover the upper surface of the core layer 32 . For example, a photosensitive resin layer (not shown) to be the cladding layer 33 is formed on the entire upper surface of the cladding layer 31, exposed and developed based on the photolithography method, and then cured by curing the photosensitive resin layer. A clad layer 33 is formed.

Next, in the step shown in FIG. 6A, a protective film 70 is formed on the upper surface of the cladding layer 33 . For example, the protective film 70 covering the entire upper surface of the clad layer 33 is attached to the upper surface of the clad layer 33 . As the protective film 70, for example, a polyester or PET (polyethylene terephthalate) film coated with a release agent can be used. As the release agent, a silicone-based release agent or a fluorine-based release agent can be used. The surface of the protective film 70 to which the release agent is applied is adhered to the upper surface of the clad layer 33 . The thickness of the protective film 70 can be, for example, about 10 μm to 50 μm.

Subsequently, in the step shown in FIG. 6B, grooves 35 having inclined surfaces 36 are formed at desired portions of the clad layers 31 and 33 . The groove portion 35 is formed so as to penetrate the protective film 70 in the thickness direction and penetrate the clad layer 33 in the thickness direction. The groove portion 35 is formed, for example, so as to extend halfway in the thickness direction of the clad layer 31 . The groove portion 35 is formed, for example, so as to penetrate the core layer 32 in the thickness direction. The groove portion 35 is inclined with respect to the X-axis direction and the Z-axis direction so that the inclined surface 36 is inclined at a predetermined angle (for example, 45 degrees) with respect to the extension direction (light propagation direction) of the core layer 32. It is formed to extend at The groove portion 35 is formed, for example, so as to extend from the upper surface of the protective film 70 in an inclined state so as to gradually approach the end surface 32</b>A of the core layer 32 in the extending direction. In the example shown in FIG. 6B, the groove portion 35 is formed to extend obliquely downward to the left. For example, the groove 35 is formed in a tapered shape in which the opening width decreases from the upper side (upper surface side of the protective film 70) toward the lower side (bottom side) in FIG. 6B. The groove portion 35 is formed, for example, in the shape of a truncated quadrangular pyramid in which the opening width at the bottom surface is smaller than the opening width at the upper opening end.

Of the inner wall surfaces of the groove portion 35, a facing surface 35A that faces the inclined surface 36 is composed of, for example, the protective film 70, the clad layers 31 and 33, and the core layer 32. As shown in FIG. That is, part of the facing surface 35A is configured by the end surface 32A of the core layer 32. As shown in FIG. 35 A of opposing surfaces are formed in the inclined surface which inclines with respect to the extension direction of the core layer 32. As shown in FIG. That is, the end surface 32A of the core layer 32 after this step is formed as an inclined surface that is inclined with respect to the extending direction of the core layer 32 . The facing surface 35A overlaps with a part of the inclined surface 36 in plan view in the Z-axis direction.

The groove portion 35 described above can be formed by, for example, a laser processing method using an excimer laser or a YAG laser. For example, if high dimensional accuracy is required for the depth of the groove 35, it is preferable to use an excimer laser. Since the excimer laser has a high degree of accuracy in processing depth in one shot, that is, in one irradiation, the groove portion 35 can be processed to a target depth with high accuracy.

In the laser processing method, the protective film 70, the clad layers 31 and 33, and the core layer 32 are obliquely processed by the laser beam that is obliquely incident on the upper surface of the protective film 70 (see arrows in the drawing). Thereby, the groove portion 35 having the inclined surface 36 and the facing surface 35A is formed. If an excimer laser is used, for example, the laser has a taper angle of 7 degrees inward from the central axis. In this case, in order to set the inclination angle of the inclined surface 36 with respect to the light propagation direction to 45 degrees, the irradiation angle of the excimer laser is set to 52 degrees (=45 degrees+7 degrees).

In this example, the groove 35 is formed to extend from the upper surface of the protective film 70 to the middle of the clad layer 31 in the thickness direction, but the depth of the groove 35 is not limited to this. For example, the groove portion 35 may be formed so as to extend from the top surface of the protective film 70 to the top surface of the wiring pattern 22 .

Next, in the step shown in FIG. 7A, the protective film 70 is used as a mask to selectively coat the inclined surface 36 of the groove 35 with a glossy metal film 71 . As a method for attaching the metal film 71 to the inclined surface 36, for example, a sputtering method or a vapor deposition method can be used. The metal film 71 is formed by laminating a chromium (Cr) layer and a gold (Au) layer in order, for example.

The metal film 71 is formed, for example, so as to cover the entire upper surface of the protective film 70 . The metal film 71 is formed, for example, so as to cover the inner wall surface of the groove 35 exposed from the protective film 70 . The metal film 71 is formed, for example, so as to cover a portion of the inner wall surface of the groove portion 35 that does not overlap the protective film 70 in plan view. The metal film 71 is formed, for example, so as to cover a portion of the inclined surface 36 of the groove portion 35 that does not overlap the opposing surface 35A in plan view. Specifically, the metal film 71 of this example includes the inclined surface 36 formed by the protective film 70, the inclined surface 36 formed by the clad layer 33, and a part of the inclined surface 36 formed by the clad layer 31. It is formed so as to cover the The metal film 71 formed to cover the inclined surface 36 in this manner is formed continuously with the metal film 71 covering the entire upper surface of the protective film 70 . Here, the facing surface 35A is formed so as to overlap the protective film 70 in plan view. Therefore, when the metal film 71 is deposited by a sputtering method, a vapor deposition method, or the like, the metal film 71 is not deposited on the facing surface 35A.

In this step, the protective film 70 in which the grooves 35 are formed by laser processing in the previous step is used as it is as a mask for forming the metal film. That is, the grooves 35 of the protective film 70 formed by laser processing become the openings of the mask for forming the metal film as they are. Therefore, it is possible to prevent the metal film formation mask from being displaced. In addition, it is possible to prevent the planar shape of the opening of the metal film forming mask from becoming larger than the planar shape of the groove 35 . Thereby, the metal film 71 can be formed only on the inner wall surface of the groove portion 35 .

Subsequently, protective film 70 is removed. For example, the protective film 70 is removed from the top surface of the clad layer 33 . When the protective film 70 is peeled off, the metal film 71 formed on the surface of the protective film 70 is removed. As a result, as shown in FIG. 7B, only the metal film 71 formed on the inclined surfaces 36 of the grooves 35 formed in the cladding layers 31 and 33 remains, and the metal film 71 constitutes the optical path conversion mirror 37. be done. Also, the upper surface of the clad layer 33 is exposed to the outside.

Next, in the step shown in FIG. 8(a), openings 38 are formed at desired locations in the clad layers 31, 33 and the core layer 32 so as to penetrate the clad layers 31, 33 and the core layer 32 in the thickness direction. do. The opening 38 is formed, for example, so as to expose part of the upper surface of the wiring pattern 22 . The opening 38 is formed, for example, at a position corresponding to the facing surface 35A shown in FIG. 7(b). The opening 38 is formed, for example, at a position separated from the optical path conversion mirror 37 in the X-axis direction. The opening 38 is formed, for example, such that its inner wall surface is a vertical surface extending perpendicularly to the extension direction of the core layer 32 (light propagation direction). Specifically, the opening 38 is formed such that the end face 32A of the core layer 32 is a vertical plane extending perpendicularly to the light propagation direction (here, the X-axis direction). In this step, the end surface 32A of the core layer 32 is formed from an inclined surface to a vertical surface by shaving part of the end portion of the core layer 32 when forming the openings 38 .

The opening 38 can be formed, for example, by a laser processing method using an excimer laser or YAG laser. When using an excimer laser, for example, the irradiation angle of the excimer laser is set to 7 degrees.

Subsequently, in the step shown in FIG. 8B, a clad layer 34 is formed on the upper surface of the clad layer 33 to cover the entire upper surface of the clad layer 33 and to fill the grooves 35 and the openings 38 . For example, a photosensitive resin layer (not shown) to be the cladding layer 34 is formed on the entire upper surface of the cladding layer 33, exposed and developed based on photolithography, and then cured by curing the photosensitive resin layer. A clad layer 34 is formed. Through the steps described above, the optical waveguide 30 having a structure in which the core layer 32 is surrounded by the clad layers 31 , 33 and 34 is formed on the wiring substrate 20 .

Next, in the process shown in FIG. 9A, an opening 30X is formed at a desired location of the optical waveguide 30 to expose a part of the wiring pattern 22 as a connection pad P1. The opening 30X can be formed, for example, by a laser processing method using an excimer laser or YAG laser. If the cladding layers 31, 33, and 34 are formed using a photosensitive resin, the required openings 30X may be formed by photolithography, for example.

Next, in the step shown in FIG. 9B, solder 40 is formed on the connection pads P1 exposed from the openings 30X. The solder 40 can be formed, for example, by applying solder paste. Through the manufacturing process described above, the optical waveguide device 10 before mounting the optical element 50 (see FIG. 1) can be manufactured.

Subsequently, in the step shown in FIG. 10A, an optical element 50 having electrode terminals 51 and light emitting/receiving portions 52 is prepared. Next, the electrode terminals 51 of the optical element 50 are positioned on the connection pads P1 of the wiring board 20, the solder 40 is melted, and the electrode terminals 51 of the optical element 50 are electrically connected to the connection pads P1. As a result, the optical element 50 is flip-chip mounted on the wiring substrate 20 . At this time, the light emitting/receiving part 52 of the optical element 50 is arranged directly above the optical path conversion mirror 37, and arranged so that the optical axis center A1 of each optical element 50 and the plane center of the optical path conversion mirror 37 substantially coincide. . Thereby, the optical element 50 is optically coupled to the optical waveguide 30 (core layer 32 ) by the optical path conversion mirror 37 .

10B, an underfill resin 60 is formed so as to fill the gap between the optical element 50 and the wiring substrate 20 on which the optical waveguide 30 is laminated. The underfill resin 60 is also filled in the openings 30X.

The optical waveguide device 10 of the present embodiment can be manufactured by the manufacturing process described above.
Next, the effects of this embodiment will be described.
(1) The grooves 35 are individually provided corresponding to the respective core layers 32 . Therefore, compared with the conventional groove portion 113, the planar shape of the groove portion 35 can be formed smaller. As a result, it is possible to prevent the design of the optical waveguide 30 from being restricted by the groove 35, so that the degree of freedom in designing the optical waveguide 30 can be improved.

For example, as in the conventional optical waveguide device 100 shown in FIG. 25, when the groove portion 113 is formed over the entire length of the substrate 130 in the Y-axis direction, the opening portion 110X into which the electrode terminal of the optical element is inserted and the The position of opening 110X is restricted so that it does not interfere with groove 113 . For example, it is necessary to set a large distance between the opening 110X and the groove 113 in the X-axis direction.

On the other hand, in the optical waveguide device 10 of the present embodiment, since the planar shape of the groove 35 is formed small, the opening 30X can be formed at a position not overlapping the groove 35 in the X-axis direction. Therefore, in the optical waveguide device 10, the distance between the opening 30X and the groove 35 in the X-axis direction can be set narrow. Accordingly, even when the distance between the electrode terminals 51 of the optical element 50 and the light emitting/receiving section 52 is narrow, the optical element 50 can be suitably mounted on the wiring board 20 .

(2) The inclined surfaces 36 of the grooves 35 are formed only on the clad layers 31 and 33 . That is, the inclined surface 36 is composed only of the clad layers 31 and 33 . Also, the optical path conversion mirror 37 is not in contact with the core layer 32 and is provided apart from the core layer 32 .

With this configuration, the number of interfaces in the optical waveguide 30 can be reduced compared to the case where the inclined surface 36 is composed of the clad layers 31 and 33 and the core layer 32 . Thereby, the optical propagation loss in the optical waveguide 30 can be reduced, and the reliability of the optical waveguide 30 can be improved.

(3) A clad layer 34 is provided to fill the groove 35 . Accordingly, since the optical path conversion mirror 37 is not exposed to the outside, it is possible to prevent the optical path conversion mirror 37 from being stained or damaged.

(4) The optical path conversion mirror 37 is covered only with the clad layers 31, 33, and 34. As a result, the optical path conversion mirror 37 can be covered only with the clad layers 31, 33, 34 made of the same material.

(5) The end face 32A of the core layer 32 facing the optical path conversion mirror 37 is formed in a vertical plane extending perpendicularly to the extending direction of the core layer 32 (light propagation direction). Thereby, it is possible to suppress the light from being reflected in an unintended direction at the end face 32A of the core layer 32 . Therefore, the optical propagation loss in the optical waveguide 30 can be reduced.

(6) By forming the opening 38, the end face 32A of the core layer 32 is formed in a vertical plane. As a result, the end surface 32A of the core layer 32 can be formed vertically with high accuracy. Therefore, the optical propagation loss in the optical waveguide 30 can be suitably reduced.

(7) The protective film 70 covering the upper surface of the cladding layer 33 was formed before forming the grooves 35 , and the grooves 35 were formed by a laser incident obliquely on the upper surface of the protective film 70 . Thereafter, using the protective film 70 as it is as a mask for forming a metal film, an optical path conversion mirror 37 made of a metal film 71 was formed on the inclined surface 36 of the groove portion 35 . According to this manufacturing method, the grooves 35 of the protective film 70 formed by laser processing become the openings of the mask for forming the metal film as they are. Therefore, it is possible to prevent the metal film formation mask from being displaced. In addition, it is possible to prevent the planar shape of the opening of the metal film forming mask from becoming larger than the planar shape of the groove 35 . As a result, the optical path conversion mirror 37 made of the metal film 71 can be formed only on the inner wall surface of the groove portion 35 (here, the inclined surface 36). Therefore, the planar shape of the optical path conversion mirror 37 can be made smaller. Moreover, it is not necessary to provide a mask for forming a metal film separately from the protective film 70 .

(8) For example, in the conventional method of manufacturing the optical waveguide device 100, as shown in FIG. A mask 140 having a is formed. At this time, the opening 140X is formed wider than the width of the groove 113 and the width of the core layer 112, for example, in consideration of dimensional errors and alignment accuracy. Therefore, the opening 140X exposes the upper surface of the upper clad layer 111B located around the groove 113. As shown in FIG. Therefore, in the conventional optical waveguide device 100, the optical path conversion mirror 115 is formed on the inclined surface 114 and on the upper surface of the upper clad layer 111B. As a result, a stepped portion is formed in the conventional optical path conversion mirror 115 . When the optical path conversion mirror 115 has a stepped portion in this manner, cracks are likely to occur in the optical waveguide 110 .

In contrast, in the optical waveguide device 10 of the present embodiment, the optical path conversion mirror 37 is formed only on the inclined surface 36, and the optical path conversion mirror 37 is formed in a flat shape without steps. Therefore, it is possible to suitably suppress the occurrence of cracks in the optical waveguide 30 .

(Second embodiment)
The second embodiment will be described below with reference to FIGS. 11 to 15. FIG. The following description will focus on differences from the first embodiment. The same members as those shown in FIGS. 1 to 10 are indicated by the same reference numerals, and detailed descriptions of these elements are omitted.

First, the structure shown in FIG. 11(a) is manufactured by performing steps similar to those shown in FIGS. 4(a) to 5(a). That is, the clad layer 31 is formed on the upper surface of the substrate body 21 and the core layer 82 is formed on the upper surface of the clad layer 31 . The core layer 82 of this example is formed longer in the X-axis direction than the core layer 32 shown in FIG. 5(a), for example.

Next, in the process shown in FIG. 11B, similarly to the process shown in FIG. 5B, the clad layer 33 is formed on the upper surface of the clad layer 31 so as to cover the entire side surfaces of the plurality of core layers 82. . The clad layer 33 of this embodiment is formed so as to cover the entire upper surface of the core layer 32 .

Subsequently, in the process shown in FIG. 12A, a protective film 70 is formed on the top surface of the clad layer 33 in the same manner as in the process shown in FIG. 6A.
Next, in the process shown in FIG. 12(b), grooves 85 having inclined surfaces 86 are formed in desired portions of the clad layers 31 and 33 and the core layer 82, similarly to the process shown in FIG. 6(b). . The groove portion 85 is formed so as to penetrate the protective film 70 in the thickness direction and penetrate the clad layer 33 in the thickness direction. The grooves 85 are formed to penetrate the core layer 82 in the thickness direction and divide the core layer 82 . The groove portion 85 is formed, for example, so as to extend halfway in the thickness direction of the clad layer 31 . The groove portion 85 is formed with respect to the X-axis direction and the Z-axis direction so that the inclined surface 86 is inclined at a predetermined angle (for example, 45 degrees) with respect to the extension direction of the core layer 82 (here, the X-axis direction). It is formed to extend in an inclined state. The groove portion 85 is formed, for example, in the shape of a truncated quadrangular pyramid in which the opening width at the bottom surface is smaller than the opening width at the upper opening end.

The inclined surface 86 of the groove portion 85 is composed of, for example, the protective film 70, the clad layers 31 and 33, and the core layer 82. As shown in FIG. That is, part of the inclined surface 86 is formed by the end surface of the core layer 82 . Of the inner wall surfaces of the groove portion 85, a facing surface 85A that faces the inclined surface 86 is composed of the protective film 70, the clad layers 31 and 33, and the core layer 82, for example. That is, part of the facing surface 85A is configured by the end surface 82A of the core layer 82. As shown in FIG. 85 A of opposing surfaces are formed in the inclined surface which inclines with respect to the extension direction of the core layer 82. As shown in FIG. That is, the end surface 82A of the core layer 82 after this step is formed as an inclined surface that is inclined with respect to the extension direction of the core layer 82 . The facing surface 85A partially overlaps the inclined surface 86 in plan view in the Z-axis direction.

The groove portion 85 described above can be formed by, for example, a laser processing method using an excimer laser or a YAG laser.
Next, in the step shown in FIG. 13A, the protective film 70 is used as a mask to selectively coat the inclined surfaces 86 of the grooves 85 with a glossy metal film 71 . The metal film 71 is formed, for example, so as to cover the entire upper surface of the protective film 70 . The metal film 71 is formed, for example, so as to cover a portion of the inner wall surface of the groove portion 85 that does not overlap the protective film 70 in plan view. The metal film 71 is formed, for example, so as to cover a portion of the inclined surface 86 of the groove portion 85 that does not overlap the facing surface 85A in plan view. Specifically, the metal film 71 of this example includes an inclined surface 86 formed by the protective film 70, an inclined surface 86 formed by the clad layer 33, an inclined surface 86 formed by the core layer 32, and a clad layer. It is formed so as to cover a portion of the inclined surface 86 configured by the layer 31 . Here, the facing surface 85A is formed so as to overlap the protective film 70 in plan view. Therefore, when the metal film 71 is deposited by a sputtering method, a vapor deposition method, or the like, the metal film 71 is not deposited on the facing surface 85A.

Subsequently, the protective film 70 is peeled off from the top surface of the clad layer 33 . When the protective film 70 is peeled off, the metal film 71 formed on the surface of the protective film 70 is removed. As a result, as shown in FIG. 13B, only the metal film 71 formed on the inclined surface 86 of the groove 85 formed in the clad layers 31 and 33 and the core layer 82 remains, and the metal film 71 changes the optical path. A mirror 37 is constructed. That is, the optical path conversion mirror 37 of this example is in contact with the core layer 82 and the clad layers 31 and 33 .

Next, in the process shown in FIG. 14A, similar to the process shown in FIG. An opening 38 is formed through the thickness of 82 . The opening 38 is formed, for example, so as to expose part of the upper surface of the wiring pattern 22 . The opening 38 is formed, for example, such that the end face 82A of the core layer 82 is a vertical plane extending perpendicularly to the extending direction of the core layer 82 (light propagation direction). In this step, the end surface 82A of the core layer 82 is formed from an inclined surface to a vertical surface by cutting a portion of the end portion of the core layer 82 when forming the opening 38 .

Subsequently, in the process shown in FIG. 14(b), the upper surface of the clad layer 33 is entirely covered and the groove 85 and the opening 38 are formed on the upper surface of the clad layer 33, similarly to the process shown in FIG. 8(b). A filling cladding layer 34 is formed. Through the above steps, the optical waveguide 30 having a structure in which the core layer 82 is surrounded by the clad layers 31 , 33 and 34 is formed on the wiring substrate 20 . At this time, the optical path conversion mirror 37 is surrounded by the clad layers 31 , 33 , 34 and the core layer 82 .

Next, in the process shown in FIG. 15A, similarly to the process shown in FIG. 9A, an opening 30X is formed at a desired location of the optical waveguide 30 to expose a part of the wiring pattern 22 as a connection pad P1. Form. Subsequently, solder 40 is formed on the connection pads P1 exposed from the openings 30X. By the above manufacturing process, the optical waveguide device 10A before mounting the optical element 50 (see FIG. 15B) can be manufactured.

Next, in the step shown in FIG. 15B, an optical element 50 having electrode terminals 51 and light emitting/receiving portions 52 is prepared. Subsequently, the electrode terminals 51 of the optical element 50 are positioned on the connection pads P1 of the wiring board 20, the solder 40 is melted, and the electrode terminals 51 of the optical element 50 are electrically connected to the connection pads P1. At this time, the light emitting/receiving part 52 of the optical element 50 is arranged directly above the optical path conversion mirror 37, and arranged so that the optical axis center A1 of each optical element 50 and the plane center of the optical path conversion mirror 37 substantially coincide. . Thereby, the optical element 50 is optically coupled to the optical waveguide 30 (core layer 82 ) by the optical path conversion mirror 37 .

Next, an underfill resin 60 is formed so as to fill the gap between the optical element 50 and the wiring substrate 20 on which the optical waveguide 30 is laminated. The underfill resin 60 is also filled in the openings 30X.

The optical waveguide device 10A of the present embodiment can be manufactured by the manufacturing process described above.
According to the present embodiment described above, the same effects as (1), (3), (5) to (8) of the first embodiment can be obtained.

(Third embodiment)
The third embodiment will be described below with reference to FIGS. 16 to 22. FIG. The following description will focus on differences from the first embodiment. The members that are the same as those shown in FIGS. 1 to 15 are denoted by the same reference numerals, and detailed descriptions of these elements are omitted.

As shown in FIG. 16, the optical waveguide device 10B has a wiring board 20, an optical waveguide 90 formed on the wiring board 20, and an optical element 50. As shown in FIG.
The optical waveguide 90 is formed on the upper surface of the substrate body 21 of the wiring substrate 20 . The optical waveguide 90 has a clad layer 91 , a core layer 92 , a clad layer 93 and a clad layer 94 .

The cladding layer 91 is formed on the upper surface of the substrate body 21 . The clad layer 91 is formed, for example, on the upper surface of the substrate body 21 so as to cover the wiring pattern 22 . One or more core layers 92 are formed on the upper surface of the clad layer 91 .

As shown in FIG. 17, two core layers 92 are formed on the upper surface of the clad layer 91 of this embodiment. Each core layer 92 is for propagating an optical signal. Each core layer 92 is formed, for example, in an elongated shape. Each core layer 92 is formed, for example, in a belt shape extending along the X-axis direction. The extension direction of each core layer 92 of this embodiment matches the X-axis direction. Each core layer 92 is formed in, for example, a quadrangular prism shape. A plurality of core layers 92 are provided side by side along the Y-axis direction orthogonal to the extending direction of the core layers 92 . A plurality of core layers 92 are formed, for example, to extend in parallel. 17 is a top plan view of the optical waveguide device 10B shown in FIG. 16, in which the cladding layer 94, the optical element 50, and the like are depicted transparently.

As shown in FIG. 16, the clad layer 93 is formed on the top surface of the clad layer 91 . The cladding layer 93 is formed so as to cover the end surface 92A of each core layer 92 in the extending direction (here, the X-axis direction). Clad layer 93 is formed to cover only end surface 92A of core layer 92 . The clad layer 93 is formed in contact with the end surface 92A of each core layer 92 . As shown in FIG. 17, the clad layer 93 is provided corresponding to each core layer 92, for example. That is, in the optical waveguide 90 of this example, two clad layers 93 are formed on the upper surface of the clad layer 91 . Each clad layer 93 is formed, for example, so as to extend in a strip shape along the X-axis direction. Each clad layer 93 is formed, for example, so as to extend from the end face 92A of the core layer 92 in the direction opposite to the X arrow (right side in the drawing). The dimension of each cladding layer 93 along the Y-axis direction (that is, the width dimension) is formed to be shorter than the width dimension of each core layer 92 . A plurality of clad layers 93 are arranged side by side along the Y-axis direction perpendicular to the extending direction of the core layer 92 . The multiple clad layers 93 are formed, for example, to extend in parallel. Note that the cladding layer 93 may be formed so as to extend over the entire area located in the direction opposite to the X arrow (rightward in the drawing) from the end surface 92A of the core layer 92 .

As shown in FIG. 16, each clad layer 93 is formed to have substantially the same thickness as each core layer 92, for example. The upper surface of each cladding layer 93 is formed on the same plane as the upper surface of each core layer 92, for example. Each clad layer 93 may be formed thicker than the core layer 92 or may be formed thinner than the core layer 92 .

One or more (here, two) grooves 95 are formed in the clad layers 91 and 93 . Each groove 95 is provided corresponding to each core layer 92 . Each groove 95 is formed, for example, so as to extend from the upper surface of the clad layer 93 halfway in the thickness direction (Z-axis direction) of the clad layer 91 . For example, the bottom surface of the groove portion 95 is positioned midway in the thickness direction of the clad layer 91 . Each groove 95 has, for example, an inclined surface 96 for converting the optical path by 90 degrees. The inclined surface 96 constitutes part of the inner wall surface of the groove portion 95 . The inclined surface 96 is formed, for example, at a predetermined angle (for example, 45 degrees) with respect to the extending direction (X-axis direction) of the core layer 92 . That is, the inclined surface 96 is formed at an angle of 45 degrees with respect to the propagation direction (advancing direction) of the light propagating through the core layer 92 . In other words, the groove portion 95 extends so that the inclined surface 96 is inclined at 45 degrees with respect to the extension direction (light propagation direction) of the core layer 92, and is inclined with respect to the X-axis direction and the Z-axis direction. formed. The groove portion 95 is formed, for example, so as to extend from the upper surface of the clad layer 93 toward the end surface 92A of the core layer 92 in an inclined state. In this example, the groove portion 95 is formed to extend obliquely downward to the left. For example, the groove 95 is formed in a tapered shape in which the opening width decreases from the upper side (upper surface side of the clad layer 93) toward the lower side (bottom side) in FIG. The groove portion 95 is formed, for example, in the shape of a truncated quadrangular pyramid in which the opening width at the bottom surface is smaller than the opening width at the upper opening end. The groove portion 95 is formed, for example, so that a portion of the bottom surface thereof overlaps the core layer 92 in plan view in the Z-axis direction. However, the bottom surface of the groove portion 95 is provided at a position separated from the core layer 92 in the Z-axis direction.

The inclined surface 96 is formed, for example, so as to extend from the upper surface of the clad layer 93 halfway in the thickness direction of the clad layer 91 . The inclined surface 96 is formed only on the clad layers 91 and 93, for example. In other words, the inclined surface 96 is not formed in the core layer 92 . The inclined surface 96 is provided apart from the core layer 92, for example. The inclined surface 96 is provided apart from the end surface 92A in the extending direction of the core layer 92 in the X-axis direction. That is, the inclined surface 96 does not contact the core layer 92 . However, the inclined surface 96 is formed on an extension of the central axis of the core layer 92 in the X-axis direction. The inclined surface 96 is formed so as to face the end surface 92A of the core layer 92 in the X-axis direction.

The inner wall surface of the groove portion 95 has a facing surface 97 that faces the inclined surface 96 . The facing surface 97 is formed to face the inclined surface 96 in the X-axis direction. The facing surface 97 is formed, for example, so as to extend from the upper surface of the clad layer 93 halfway in the thickness direction of the clad layer 91 . The facing surface 97 is formed only on the clad layers 91 and 93, for example. In other words, the facing surface 97 is not formed on the core layer 92 . The facing surface 97 is provided apart from the core layer 92, for example. That is, the facing surface 97 does not contact the core layer 92 . A portion of the facing surface 97 is formed to face the end surface 92A of the core layer 92 in the X-axis direction. The facing surface 97 is formed, for example, as an inclined surface that is inclined with respect to the extending direction of the core layer 92 . A part of the upper end side of the facing surface 97 overlaps a part of the inclined surface 96 in a plan view seen from the Z-axis direction, for example. A part of the lower end side of the facing surface 97 overlaps a part of the core layer 92 in a plan view seen from the Z-axis direction, for example.

As shown in FIG. 17, the plurality of grooves 95 are provided apart from each other in the Y-axis direction. That is, the plurality of grooves 95 are provided at predetermined intervals in the Y-axis direction.

The planar shape of each groove portion 95 (inclined surface 96) is, for example, rectangular. The planar shape of each groove portion 95 is, for example, a trapezoidal shape in which the lengths of the upper base and the lower base are different from each other. Each groove portion 95 is formed, for example, such that the opening width (that is, the opening width along the Y-axis direction) becomes narrower as it approaches the core layer 92 from the farthest end portion from the core layer 92 in the X-axis direction. ing. The opening width of each groove 95 is, for example, set wider than the dimension of the core layer 92 along the Y-axis direction (that is, the width dimension).

The inclined surface 96 has, for example, a rectangular front shape when viewed from the X-axis direction (the central axis of the core layer 92). The front shape of the inclined surface 96 is, for example, a trapezoidal shape in which the lengths of the upper base and the lower base are different from each other. The inclined surface 96 is formed, for example, so that the dimension along the Y-axis direction (that is, the width dimension) becomes shorter from the upper end to the lower end. That is, the inclined surface 96 is formed such that the width dimension thereof decreases from the upper surface side of the clad layer 93 toward the lower surface side of the clad layer 91 .

Each inclined surface 96 is formed with an optical path conversion mirror 37 for converting the optical path by 90 degrees. That is, the optical waveguide 90 is provided with a plurality of (here, two) optical path conversion mirrors 37 . The plurality of optical path conversion mirrors 37 are provided, for example, apart from each other in the Y-axis direction. That is, the plurality of optical path conversion mirrors 37 are provided at predetermined intervals in the Y-axis direction. As a material of the optical path conversion mirror 37, for example, a metal material having good light reflectivity can be used. As the material of the optical path conversion mirror 37, for example, metal materials such as gold, silver, and aluminum can be used.

As shown in FIG. 16, each optical path conversion mirror 37 is formed so as to cover the inclined surface 96, for example. For example, each optical path conversion mirror 37 is formed so as to cover the portion of the inclined surface 96 that does not overlap the opposing surface 97 in plan view in the Z-axis direction. Each optical path conversion mirror 37 is formed, for example, so as to cover the entire upper portion of the inclined surface 96 . Each optical path conversion mirror 37 is formed, for example, so as to cover the upper portion of the inclined surface 96 over the entire length in the Y-axis direction. Each optical path conversion mirror 37 is formed, for example, so as to expose the lower portion of the inclined surface 96 . That is, the lower portion of the inclined surface 96 is exposed from the optical path conversion mirror 37 . Each optical path conversion mirror 37 is formed, for example, so as to protrude below the lower surface of the core layer 92 and the upper surface of the clad layer 91 . The upper end surface of each optical path conversion mirror 37 is formed so as to be flush with the upper surface of the clad layer 93, for example. The upper end surface of each optical path conversion mirror 37 is formed on the same plane as the upper surface of the core layer 92, for example.

Each optical path conversion mirror 37 is provided apart from the core layer 92, for example. Each optical path conversion mirror 37 is provided apart from the end face 92A in the extension direction of the core layer 92 in the X-axis direction. That is, each optical path conversion mirror 37 is not in contact with the core layer 92 . However, each optical path conversion mirror 37 is formed on an extension of the central axis of the core layer 92 in the X-axis direction. Each optical path conversion mirror 37 is formed to face the end face 92A of the core layer 92 in the X-axis direction.

Each optical path conversion mirror 37 is formed only on the inclined surface 96, for example. In other words, each optical path conversion mirror 37 is not formed on the upper surface of the clad layer 93 or the upper surface of the core layer 92 . Each optical path conversion mirror 37 is formed flat on the inclined surface 96, for example. For example, each optical path conversion mirror 37 is formed in a flat shape without steps. For example, each optical path conversion mirror 37 is formed in a thin plate shape without steps.

As shown in FIG. 17, the planar shape of each optical path conversion mirror 37 is, for example, formed along the planar shape of the inclined surface 96 . The planar shape of each optical path conversion mirror 37 is, for example, rectangular. The planar shape of each optical path conversion mirror 37 is, for example, a trapezoidal shape in which the lengths of the upper base and the lower base are different from each other. For example, in the X-axis direction, each optical path conversion mirror 37 has a dimension (that is, a width dimension) along the Y-axis direction from an upper end portion farthest from the core layer 92 toward a lower end portion closer to the core layer 92. designed to be short. The width dimension of each optical path conversion mirror 37 is set wider than the width dimension of the core layer 92, for example.

As shown in FIG. 16, the clad layer 94 is formed, for example, so as to cover the upper surface of the clad layer 93 . The cladding layer 94 is formed, for example, so as to fill the groove portion 95 . The clad layer 94 is formed, for example, to cover the optical path conversion mirror 37 . The clad layer 94 is formed, for example, so as to cover the entire surface of the optical path conversion mirror 37 exposed from the clad layers 91 and 93 . As a result, the entire surface of the optical path conversion mirror 37 is covered with the clad layers 91 , 93 and 94 . That is, the optical path conversion mirror 37 is covered only with the clad layers 91 , 93 and 94 . In other words, the optical path conversion mirror 37 is embedded in the clad layers 91 , 93 and 94 .

The cladding layer 94 is formed, for example, to fill the space between adjacent core layers 92 . The clad layer 94 is formed to cover the entire side surface of each core layer 92 . The clad layer 94 is formed, for example, so as to cover the entire upper surface of the core layer 92 . As described above, the optical waveguide 90 has a structure in which the clad layer 91 and the core layer 92, and the clad layer 93 and the clad layer 94 are laminated in this order on the upper surface of the substrate body 21, and the core layer 92 is the clad layer. It has a structure surrounded by 91 , a clad layer 93 and a clad layer 94 .

The clad layer 94 is formed, for example, to fill the space between adjacent clad layers 93 . The clad layer 94 is formed, for example, so as to cover the entire side surface of each clad layer 93 .

Basically, the same materials can be used as materials for the clad layers 91, 93, 94 and the core layer 92. As shown in FIG. For example, as materials for the clad layers 91, 93, 94 and the core layer 92, a resin material having optical transparency in the wavelength range used by the optical element 50 can be used. Specifically, as materials for the clad layers 91, 93, 94 and the core layer 92, acrylic resins such as polymethyl methacrylate, epoxy resins, silicone resins, and the like can be used. However, the clad layers 91, 93, and 94 formed around the core layer 92 are used as the material for the core layer 92 so that the optical signal is propagated only within the core layer 92. A material with a higher refractive index than the material to be used is selected. The difference in refractive index between the core layer 92 and the clad layers 91, 93, and 94 is not particularly limited, but is preferably about 0.3% to 5.5%, more preferably 0.8% to 2.2%. degree is more preferred.

The thickness of the clad layer 91, specifically, the thickness from the upper surface of the wiring pattern 22 to the upper surface of the clad layer 91 can be, for example, approximately 10 μm to 15 μm. The thickness of the core layer 92, specifically, the thickness from the upper surface of the clad layer 91 to the upper surface of the core layer 92 can be, for example, approximately 30 μm to 80 μm. The width dimension of the core layer 92 can be, for example, about 20 μm to 50 μm. The pitch of the core layers 92 can be, for example, about 100 μm to 300 μm. The thickness of the clad layer 93, specifically, the thickness from the upper surface of the clad layer 91 to the upper surface of the clad layer 93 can be, for example, approximately 30 μm to 90 μm. The width dimension of the cladding layer 93 can be, for example, about 50 μm to 100 μm. The thickness of the clad layer 94, specifically, the thickness from the upper surface of the clad layer 93 to the upper surface of the clad layer 94 can be, for example, approximately 30 μm to 80 μm.

In FIG. 16, the clad layers 91, 93, and 94 are distinguished by solid lines for easy understanding. For example, in the optical waveguide 90, the interfaces between the cladding layers 91, 93, and 94 may disappear and the boundaries may not be clear.

The optical waveguide 90 is formed with an opening 90X for exposing a portion of the wiring pattern 22 as a connection pad P1. The openings 90X are provided at positions corresponding to the electrode terminals 51 of the optical element 50 . The opening 90X is provided, for example, at a position away from the optical path conversion mirror 37 in the direction away from the core layer 92 . The opening 90X is formed, for example, so as to penetrate the clad layers 91, 93, 94 in the thickness direction. The opening 90X is, for example, tapered such that the opening width (opening diameter) decreases from the upper side (the upper surface side of the cladding layer 94) toward the lower side (the wiring pattern 22 side) in FIG. For example, the opening 90X is formed in an inverted truncated cone shape in which the opening diameter of the lower opening end is smaller than the opening diameter of the upper opening end.

Solders 40 are formed on the connection pads P1 to electrically connect the connection pads P1 and the electrode terminals 51 of the optical element 50 . As the material of the solder 40, for example, an alloy containing Pb, an alloy of Sn and Cu, an alloy of Sn and Ag, an alloy of Sn, Ag and Cu, or the like can be used.

If necessary, an OSP process may be performed on the wiring pattern 22 exposed from the opening 90X to form an OSP film, and the solder 40 may be formed on the OSP film. Alternatively, a metal layer may be formed on the wiring pattern 22 exposed from the opening 90X, and the solder 40 may be formed on the metal layer. Examples of metal layers include Au layers, Ni/Au layers, and Ni/Pd/Au layers.

As shown in FIG. 17, two openings 90X are formed in each core layer 92 in the optical waveguide 90 . The plurality of openings 90X are provided side by side along the Y-axis direction, for example. The plurality of openings 90X are provided, for example, at predetermined intervals in the Y-axis direction. Each opening 90X is provided, for example, at a position not overlapping the groove 95 in the X-axis direction. That is, the one groove 95 and the two openings 90X are provided at different positions in the Y-axis direction. For example, one groove 95 and two openings 90X are alternately provided. For example, the groove 95 is provided between two openings 90X in the Y-axis direction.

As shown in FIG. 16, the optical element 50 is mounted on the wiring board 20 on which the optical waveguide 90 is laminated (integrated). For example, the electrode terminals 51 of the optical element 50 are inserted into the openings 90X and are electrically connected to the connection pads P1 of the wiring board 20 via the electrode terminals 51 and the solder 40 . Thereby, each optical element 50 is electrically connected to the wiring pattern 22 of the wiring board 20 via the electrode terminal 51 and the solder 40 . That is, each optical element 50 is flip-chip mounted on the wiring board 20 . At this time, the optical element 50 is mounted on the wiring board 20 so that the light emitting/receiving section 52 faces the optical path conversion mirror 37 . The optical element 50 is mounted on the wiring board 20 so that the light emitting/receiving section 52 is arranged right above the optical path conversion mirror 37, for example. Specifically, the optical element 50 is mounted on the wiring board 20 so that the optical axis center A1 overlaps a predetermined position of the optical path conversion mirror 37 (for example, the center of the inclined surface of the optical path conversion mirror 37) in plan view. there is In other words, the opening 90X is formed at a position where the electrode terminal 51 of the optical element 50 can be inserted while the optical axis center A1 and the predetermined position of the optical path conversion mirror 37 are aligned.

An underfill resin 60 is formed between the optical element 50 and the optical waveguide 90 and wiring board 20 . The underfill resin 60 is formed, for example, so as to fill the gap between the upper surface of the clad layer 94 and the lower surface of the optical element 50 . The underfill resin 60 is formed, for example, to fill the opening 90X. The underfill resin 60 is a resin for improving the connection strength of the connection portions between the electrode terminals 51 of the optical element 50 and the connection pads P1 of the wiring board 20 . As the material of the underfill resin 60, for example, a resin material having optical transparency in the wavelength range used by the optical element 50 can be used. As the material of the underfill resin 60, for example, the same resin material as that of the clad layers 91, 93, and 94 can be preferably used.

When the optical element 50 is a light emitting element, the light emitted from the optical axis center A1 (light emitting point) of the light emitting/receiving portion 52, which is the light emitting portion, passes through the groove portion 95 of the optical waveguide 90 as indicated by the arrow in the drawing. is incident on The light incident on the groove portion 95 is formed on the inclined surface 96 and is incident on the core layer 92 of the optical waveguide 90 after the optical path is bent by 90 degrees by the optical path conversion mirror 37 . Light incident on the core layer 92 is propagated through repeated total reflection within the core layer 92 . On the other hand, when the optical element 50 is a light-receiving element, the light propagating through the core layer 92 of the optical waveguide 90 is reflected by the optical path conversion mirror 37 and emitted from the groove 95 of the optical waveguide 90 to be the light-receiving part. is incident on the optical axis center A1 of the light emitting/receiving portion 52.

(Manufacturing method of optical waveguide device 10B)
Next, a method for manufacturing the optical waveguide device 10B will be described. For convenience of explanation, the parts that will eventually become the constituent elements of the optical waveguide device 10B will be described with the reference numerals of the final constituent elements.

First, in the process shown in FIG. 18(a), the wiring substrate 20 is prepared in the same manner as in the process shown in FIG. 4(a). Next, a clad layer 91 is formed on the upper surface of the substrate body 21 so as to cover the wiring pattern 22 . For example, a photosensitive resin layer (not shown) to be the cladding layer 91 is formed on the entire upper surface of the substrate body 21, exposed and developed based on the photolithography method, and then cured by curing the photosensitive resin layer. A clad layer 91 is formed. As a method for forming the photosensitive resin layer, for example, a liquid photosensitive resin may be applied to the entire upper surface of the substrate body 21 , or a semi-cured photosensitive resin sheet may be applied to the entire upper surface of the substrate body 21 . You may make it laminate. Here, as the photosensitive resin, for example, a UV curable resin can be suitably used. As the UV curable resin, for example, a resin material containing a modified acrylate (epoxy resin, polyester resin, etc.) as a base resin, a reactive acrylic monomer required for photopolymerization, a photopolymerization initiator, and additives can be used. . The main reaction of such UV curable resins is radical polymerization. By using such a UV curable resin, processing can be performed at room temperature, and furthermore, the work time can be shortened because the resin can be cured in a shorter time than when a thermosetting resin is used. The material of the photosensitive resin layer is the same in the process of forming the core layer 92 and the clad layers 93 and 94, which will be described later.

Subsequently, in the step shown in FIG. 18B, a clad layer 93 is formed on the top surface of the clad layer 91 . In this example, a plurality of strip-shaped clad layers 93 are formed on the upper surface of the clad layer 91 . For example, a photosensitive resin layer (not shown) to be the cladding layer 93 is formed on the entire upper surface of the cladding layer 91, exposed and developed based on photolithography, and then cured by curing the photosensitive resin layer. A strip-shaped clad layer 93 is formed.

Next, in the step shown in FIG. 19A, a plurality of core layers 92 are formed on the top surface of the clad layer 91 . Each core layer 92 is formed such that an end face 92</b>A in the extending direction of the core layer 92 is in contact with the clad layer 93 . For example, a photosensitive resin layer (not shown) serving as the core layer 92 is formed on the upper surface of the clad layer 91 exposed from the clad layer 93, and after performing exposure and development based on the photolithography method, the photosensitive resin layer is cured to form the core layer 92 . Through this step, a strip-shaped core layer 92 is formed on the upper surface of the clad layer 91 .

Next, in the step shown in FIG. 19B, a protective film 72 is formed on the top surface of the cladding layer 93 . For example, the protective film 72 is attached to the top surface of the clad layer 93 and the top surface of the core layer 92 to cover the entire top surface of the clad layer 93 and the core layer 92 . As the protective film 72, for example, a polyester or polyethylene terephthalate film with a release agent applied to the surface thereof can be used. As the release agent, a silicone-based release agent or a fluorine-based release agent can be used. The surface of the protective film 72 to which the release agent is applied is adhered to the upper surface of the clad layer 93 and the upper surface of the core layer 92 . The thickness of the protective film 72 can be, for example, about 10 μm to 50 μm.

Subsequently, in the step shown in FIG. 20A, grooves 95 having inclined surfaces 96 are formed at desired portions of the clad layers 91 and 93 . The groove portion 95 is formed so as to penetrate the protective film 72 in the thickness direction and penetrate the clad layer 93 in the thickness direction. The groove portion 95 is formed, for example, so as to extend halfway in the thickness direction of the clad layer 91 . The groove portion 95 is inclined with respect to the X-axis direction and the Z-axis direction so that the inclined surface 96 is inclined at a predetermined angle (for example, 45 degrees) with respect to the extension direction (light propagation direction) of the core layer 92. It is formed to extend at The groove portion 95 is formed, for example, so as to extend from the upper surface of the protective film 72 in an inclined state so as to gradually approach the end surface 92</b>A of the core layer 92 in the extending direction. The groove portion 95 is formed apart from the core layer 92 .

The inclined surface 96 and the facing surface 97 that constitute the inner wall surface of the groove 95 are composed of, for example, the protective film 72 and the clad layers 91 and 93 . The inclined surface 96 and the facing surface 97 are not in contact with the end surface 92A of the core layer 92 . That is, the inclined surface 96 and the facing surface 97 are formed apart from the end surface 92A of the core layer 92 . The facing surface 97 is formed as an inclined surface that is inclined with respect to the extending direction of the core layer 92 . The facing surface 97 partially overlaps the inclined surface 96 in plan view in the Z-axis direction.

The groove portion 95 described above can be formed by, for example, a laser processing method using an excimer laser or a YAG laser. For example, if high dimensional accuracy is required for the depth of the groove 95, it is preferable to use an excimer laser. Since the excimer laser has a high degree of accuracy in processing depth in one shot, that is, in one irradiation, the groove portion 95 can be processed to a target depth with high accuracy.

In the laser processing method, the protective film 72 and the clad layers 91 and 93 are obliquely processed by the laser beam, which is obliquely incident on the upper surface of the protective film 72 (see arrows in the figure). Thereby, a groove portion 95 having an inclined surface 96 and an opposing surface 97 is formed. If an excimer laser is used, for example, the laser has a taper angle of 7 degrees inward from the central axis. In this case, in order to set the inclination angle of the inclined surface 96 with respect to the light propagation direction to 45 degrees, the irradiation angle of the excimer laser is set to 52 degrees (=45 degrees+7 degrees).

In this example, the groove 95 is formed to extend from the upper surface of the protective film 72 halfway in the thickness direction of the clad layer 91, but the depth of the groove 95 is not limited to this. For example, the groove portion 95 may be formed so as to extend from the top surface of the protective film 72 to the top surface of the wiring pattern 22 .

Next, in the step shown in FIG. 20B, the protective film 72 is used as a mask to selectively coat the inclined surface 96 of the groove 95 with a glossy metal film 73 . As a method for attaching the metal film 73 to the inclined surface 96, for example, a sputtering method or a vapor deposition method can be used. The metal film 73 is formed by sequentially laminating a Cr layer and an Au layer, for example.

The metal film 73 is formed, for example, so as to cover the entire upper surface of the protective film 72 . The metal film 73 is formed, for example, so as to cover the inner wall surface of the groove 95 exposed from the protective film 72 . The metal film 73 is formed, for example, so as to cover a portion of the inner wall surface of the groove portion 95 that does not overlap the protective film 72 in plan view. Specifically, the metal film 73 of this example includes an inclined surface 96 formed by the protective film 72, an inclined surface 96 formed by the clad layer 93, and a portion of the inclined surface 96 formed by the clad layer 91. It is formed so as to cover the The metal film 73 formed to cover the inclined surface 96 in this manner is formed continuously with the metal film 73 covering the entire upper surface of the protective film 72 . Here, the facing surface 97 is formed so as to overlap the protective film 72 in plan view. Therefore, when the metal film 73 is deposited by a sputtering method, a vapor deposition method, or the like, the metal film 73 is not deposited on the facing surface 97 .

In this step, the protective film 72 in which the grooves 95 are formed by the laser processing in the previous step is used as it is as a mask for forming the metal film. That is, the grooves 95 of the protective film 72 formed by laser processing become the openings of the mask for forming the metal film as they are. Therefore, it is possible to prevent the metal film formation mask from being displaced. Further, it is possible to prevent the planar shape of the opening of the metal film forming mask from becoming larger than the planar shape of the groove 95 . Thereby, the metal film 73 can be formed only on the inner wall surface of the groove portion 95 .

Subsequently, protective film 72 is removed. For example, the protective film 72 is removed from the upper surface of the clad layer 93 . When the protective film 72 is peeled off, the metal film 73 formed on the surface of the protective film 72 is removed. As a result, as shown in FIG. 21A, only the metal film 73 formed on the inclined surfaces 96 of the grooves 95 formed in the cladding layers 91 and 93 remains, and the metal film 73 constitutes the optical path conversion mirror 37. be done. Also, the upper surface of the core layer 92 and the upper surface of the clad layer 93 are exposed to the outside.

Next, in the step shown in FIG. 21B, a clad layer 94 that covers the entire upper surface of the core layer 92 and the entire upper surface of the clad layer 93 and fills the groove 95 is formed. The clad layer 94 is formed, for example, to fill the space between adjacent core layers 92 . The clad layer 94 is formed, for example, to fill the space between adjacent clad layers 93 . For example, a photosensitive resin layer (not shown) serving as the cladding layer 94 is formed on the upper surfaces of the cladding layers 91 and 93 and the core layer 92, and after exposure and development are performed based on the photolithography method, the photosensitive resin layer is formed. The cladding layer 94 is formed by curing. Through the above steps, the optical waveguide 90 having a structure in which the core layer 92 is surrounded by the clad layers 91 , 93 and 94 is formed on the wiring substrate 20 .

Next, in the step shown in FIG. 22A, an opening 90X is formed at a desired location of the optical waveguide 90 to expose a part of the wiring pattern 22 as a connection pad P1. The opening 90X can be formed, for example, by a laser processing method using an excimer laser or YAG laser. If the cladding layers 91, 93 and 94 are formed using a photosensitive resin, the required openings 90X may be formed by photolithography, for example.

Next, solder 40 is formed on the connection pads P1 exposed from the openings 90X. The solder 40 can be formed, for example, by applying solder paste. By the manufacturing process described above, the optical waveguide device 10B before mounting the optical element 50 (see FIG. 16) can be manufactured.

Subsequently, in the step shown in FIG. 22B, an optical element 50 having electrode terminals 51 and light emitting/receiving portions 52 is prepared. Next, the electrode terminals 51 of the optical element 50 are positioned on the connection pads P1 of the wiring board 20, the solder 40 is melted, and the electrode terminals 51 of the optical element 50 are electrically connected to the connection pads P1. As a result, the optical element 50 is flip-chip mounted on the wiring substrate 20 . At this time, the light emitting/receiving part 52 of the optical element 50 is arranged directly above the optical path conversion mirror 37, and arranged so that the optical axis center A1 of each optical element 50 and the plane center of the optical path conversion mirror 37 substantially coincide. . Thereby, the optical element 50 is optically coupled to the optical waveguide 90 (core layer 92 ) by the optical path conversion mirror 37 .

Next, an underfill resin 60 is formed so as to fill the gap between the optical element 50 and the wiring substrate 20 on which the optical waveguide 90 is laminated. The underfill resin 60 is also filled in the openings 90X.

The optical waveguide device 10B of the present embodiment can be manufactured by the manufacturing process described above.
According to the present embodiment described above, in addition to the effects (1) to (5), (7), and (8) of the first embodiment, the following effects can be obtained.

(9) The groove 95 is formed only in the clad layers 91 and 93, and the groove 95 is formed apart from the core layer 92. According to this configuration, the groove portion 95 can be formed while maintaining the end face 92A of the core layer 92 in a vertical plane. Therefore, it is not necessary to perform laser processing for forming the end face 92A of the core layer 92 in a vertical plane after the groove 95 is formed. Thereby, the number of times of laser processing can be reduced, and the manufacturing cost can be reduced.

(Other embodiments)
Each of the above embodiments can be implemented with the following modifications. Each of the above-described embodiments and the following modifications can be implemented in combination with each other within a technically consistent range.

- Although the optical waveguide 30 of the first and second embodiments employs a structure in which the clad layer 31, the clad layer 33, and the clad layer 34 are laminated, the structure is not limited to this.
For example, as shown in FIG. 23, the optical waveguide 30 may employ a structure having a clad layer 39 in which the clad layer 31, the clad layer 33, and the clad layer 34 shown in FIG. 1 are integrated. In the clad layer 39, the interface between the clad layer 31, the clad layer 33, and the clad layer 34 shown in FIG. 1 disappears. In this case, the optical path conversion mirror 37 is embedded in the clad layer 39 . In such an optical waveguide 30, since the number of interfaces between members is reduced, it is possible to further reduce light propagation loss.

Similarly, as the optical waveguide 90 of the third embodiment, a structure having a clad layer in which the clad layer 91, the clad layer 93, and the clad layer 94 are integrated may be adopted.
- FIG. 24 shows a state in which an electronic component 55 is mounted on the optical waveguide device 10 shown in FIG. As shown in FIG. 24, the optical waveguide device 10 of this modification includes a wiring substrate 20, an optical waveguide 30, an optical element 50, and an electronic component 55. As shown in FIG. Examples of the electronic component 55 include an IC chip such as a driver for driving the optical element 50 (light emitting element), a DSP (Digital Signal Processor) for processing the optical output signal from the optical element 50 (light receiving element), an amplifier, and the like. An embedded IC chip can be used.

The wiring board 20 has a solder resist layer 25 formed on the upper surface of the board body 21 . The solder resist layer 25 is formed, for example, in a region of the upper surface of the substrate body 21 where the optical waveguide 30 is not formed. The solder resist layer 25 is formed, for example, so as to cover the wiring pattern 22 . The solder resist layer 25 is formed with openings 25X for exposing portions of the wiring pattern 22 as connection pads P3. Solder 41 is formed on the connection pads P3 for electrically connecting the connection pads P3 and the electrode terminals 56 of the electronic component 55 . As the material of the solder 41, for example, an alloy containing Pb, an alloy of Sn and Cu, an alloy of Sn and Ag, an alloy of Sn, Ag and Cu, or the like can be used.

If necessary, the wiring pattern 22 exposed from the opening 25X may be subjected to an OSP process to form an OSP film, and the solder 41 may be formed on the OSP film. Alternatively, a metal layer may be formed on the wiring pattern 22 exposed from the opening 25X, and the solder 41 may be formed on the metal layer. Examples of metal layers include Au layers, Ni/Au layers, and Ni/Pd/Au layers.

The planar shapes of the openings 25X and the connection pads P3 can be arbitrary shapes and arbitrary sizes. For example, the planar shape of the opening 25X and the connection pad P3 can be circular with a diameter of about 50 μm to 200 μm. The thickness from the upper surface of the substrate body 21 to the upper surface of the solder resist layer 25 can be, for example, approximately 10 μm to 100 μm. As the material of the solder resist layer 25, for example, an epoxy-based or acrylic-based insulating resin can be used.

Electrode terminals 56 are formed on one surface (here, the lower surface) of the electronic component 55 . The electronic component 55 is electrically connected to the connection pads P3 of the wiring board 20 via the electrode terminals 56 and the solder 41 . That is, the electronic component 55 is flip-chip mounted on the wiring board 20 . Thereby, the electronic component 55 is electrically connected to the optical element 50 through the electrode terminals 56 , the wiring pattern 22 and the electrode terminals 51 . As the electrode terminals 56, for example, metal columns, gold bumps, or solder bumps can be used. As a material for the metal pillars, for example, copper or a copper alloy can be used. As the material of the solder bumps, for example, an alloy containing Pb, an alloy of Sn and Cu, an alloy of Sn and Ag, an alloy of Sn, Ag and Cu, or the like can be used.

One electronic component 55 may be provided corresponding to one optical element 50 , or one electronic component 55 may be provided corresponding to a plurality of optical elements 50 .
For example, an underfill resin 61 is formed between the wiring board 20 and the electronic component 55 . The underfill resin 61 is formed, for example, so as to fill the gap between the upper surface of the solder resist layer 25 and the lower surface of the electronic component 55 . The underfill resin 61 is formed, for example, so as to fill the opening 25X. The underfill resin 61 is a resin for improving the connection strength of the connection portions between the electrode terminals 56 of the electronic component 55 and the connection pads P3 of the wiring board 20 . As the material of the underfill resin 61, for example, an epoxy-based insulating resin can be used.

The electronic component 55 may be mounted on each of the optical waveguide device 10A of the second embodiment and the optical waveguide device 10B of the third embodiment.
- The underfill resin 61 may be omitted from the optical waveguide device 10 shown in FIG.

- The underfill resin 60 in each of the above embodiments may be omitted.
- The planar shape of the core layers 32, 82, 92 in each of the above embodiments is not limited to a linear shape. For example, the planar shape of the core layers 32, 82, 92 may be a shape having a curved portion, a shape having branching portions or crossing portions, a condensing portion (for example, a portion narrower than other portions), or the like. It may be formed in a shape having a light diffusing portion (for example, a portion wider than other portions).

- In the first and second embodiments, the clad layer 33 is formed so as to cover the top surfaces of the core layers 32 and 82 . Alternatively, the clad layer 33 may be formed so as to expose the upper surfaces of the core layers 32 and 82 . In this case, for example, the upper surface of the clad layer 33 is formed so as to be flush with the upper surfaces of the core layers 32 and 82 . Further, the clad layer 34 is formed so as to cover the entire upper surface of the clad layer 33 and the entire upper surfaces of the core layers 32 and 82, for example.

- In the first embodiment, the groove 35 formed in the process shown in FIG. 6B may be formed apart from the core layer 32 . In this case, the end face 32A in the extension direction of the core layer 32 can be maintained in a vertical plane after the groove 35 is formed.

- The clad layers 34 and 94 in each of the above embodiments may be omitted.
- The formation of the openings 38 in the first and second embodiments may be omitted.
- In the said 3rd Embodiment, after forming the clad layer 93, the core layer 92 was formed. Alternatively, for example, the clad layer 93 may be formed after the core layer 92 is formed.

Reference Signs List 10, 10A, 10B Optical waveguide device 20 Wiring substrate 21 Substrate body 22 Wiring pattern 30, 90 Optical waveguide 30X, 90X Opening 31, 91 Cladding layer (first clad layer)
32, 82, 92 core layer 32A, 82A, 92A end face 33, 93 clad layer (second clad layer)
34, 94 clad layer (third clad layer)
35, 85, 95 Groove 35A, 85A, 97 Opposing surface 36, 86, 96 Inclined surface 37 Optical path conversion mirror 38 Opening 39 Cladding layer 50 Optical element 51 Electrode terminal 52 Light emitting/receiving part 60 Underfill resin 70, 72 Protective film 71 , 73 metal film

Claims (10)

a first clad layer;
a plurality of core layers formed on the upper surface of the first clad layer;
a second clad layer formed on the upper surface of the first clad layer so as to cover the core layer;
a plurality of grooves provided corresponding to each of the plurality of core layers;
Provided in each groove so as to face the end face in the extension direction of each core layer in the extension direction of each core layer, and inclined at a predetermined angle with respect to the extension direction of each core layer face and
an optical path conversion mirror formed on the inclined surface;
The plurality of grooves are formed apart from each other,
The inclined surface is formed only on the first clad layer and the second clad layer,
The optical path conversion mirror is not in contact with the core layer and is provided away from the core layer,
The second clad layer is formed so as to cover only an end surface of the core layer in the extending direction of the core layer,
each of the grooves is formed apart from each of the core layers,
The optical waveguide, wherein the second clad layer covering the end face of the core layer in the extending direction is provided between the end face of the core layer in the extending direction and the groove. further comprising a third clad layer covering the upper surface of the second clad layer and filling the groove;
2. The optical waveguide according to claim 1, wherein said optical path conversion mirror is covered only with a clad layer including said first clad layer, said second clad layer and said third clad layer. 3. The optical waveguide according to claim 2, wherein said first clad layer, said second clad layer and said third clad layer are integrally formed. 4. The optical waveguide according to any one of claims 1 to 3 , wherein the end face in the extending direction of the core layer is formed in a vertical plane extending perpendicularly to the extending direction of the core layer. 5. The optical waveguide according to any one of claims 1 to 4 , wherein the optical path conversion mirror is formed only on the inclined surface and has a flat shape without steps. an optical waveguide according to any one of claims 1 to 5 ;
a wiring board on which the optical waveguide is laminated;
an optical element mounted on the wiring board;
An optical waveguide device having forming a first cladding layer;
forming a second clad layer on the upper surface of the first clad layer;
forming a core layer on the upper surface of the first cladding layer exposed from the second cladding layer, the end surface of which extends in contact with the second cladding layer;
forming a protective film on the upper surface of the second cladding layer;
It has an inclined surface inclined at a predetermined angle with respect to the extension direction of the core layer by a laser that is obliquely incident on the upper surface of the protective film, and the protective film and the second clad layer are arranged in the thickness direction. forming a groove penetrating through the
forming an optical path conversion mirror made of a metal film on the inclined surface of the groove using the protective film as a mask;
removing the protective film;
has
The method of manufacturing an optical waveguide, wherein the groove is formed apart from the core layer. forming a first cladding layer;
forming a core layer on the upper surface of the first clad layer;
forming a second clad layer covering the side surface of the core layer on the upper surface of the first clad layer;
forming a protective film on the upper surface of the second cladding layer;
It has an inclined surface inclined at a predetermined angle with respect to the extension direction of the core layer by a laser that is obliquely incident on the upper surface of the protective film, and the protective film and the second clad layer are arranged in the thickness direction. forming a groove penetrating through the
forming an optical path conversion mirror made of a metal film on the inclined surface of the groove using the protective film as a mask;
removing the protective film;
A method for manufacturing an optical waveguide having further comprising forming an opening that communicates with the groove;
The opening is formed so that the end surface of the core layer facing the optical path conversion mirror in the extending direction of the core layer is formed on a vertical surface extending perpendicularly to the extending direction of the core layer. 9. The method for manufacturing an optical waveguide according to claim 8 , wherein the core layer is partially removed. 10. The method of manufacturing an optical waveguide according to any one of claims 7 to 9 , further comprising forming a third clad layer that covers the upper surface of the second clad layer and fills the groove.