JP2012088634A - Optical waveguide device and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide device which has less transmission loss of light and can be surely made thinner.SOLUTION: An optical waveguide device 10 includes an optical waveguide structure 20 and a photoelectric transducer 43. The optical waveguide structure 20 has a plurality of optical waveguide parts 23 formed on one plane. The photoelectric transducer 43 has a plurality of optical function parts 44 and is mounted on a principal surface 21 of the optical waveguide structure 20. The number of optical waveguide parts 23 is equal to that of optical function parts 44. In each optical waveguide part 23, an optical path conversion part 31 is formed and comprises a conical recess 33. The photoelectric transducer 43 has light-emitting part groups 46 to 48 in a plurality of columns, and optical function parts 44 constituting a light-emitting part group and optical function parts 44 constituting an adjacent light-emitting part group are arranged offset from each other along a direction orthogonal to an arrangement direction of the light-emitting part groups 46 to 48.

Description

  The present invention relates to an optical waveguide device having a structure in which an optical signal propagates and a method for manufacturing the same.

  In recent years, with the development of information communication technology represented by the Internet and the dramatic improvement in the processing speed of information processing apparatuses, there is an increasing need for transmitting and receiving large-capacity data such as images. An information transmission speed of 10 Gbps or higher is desirable to exchange such a large amount of data freely through an information communication facility, and great expectations are placed on optical communication technology as a technology that can realize such a high-speed communication environment. On the other hand, signals can be transmitted at high speeds even on signal transmission paths at relatively short distances, such as connections between wiring boards in equipment, connections between semiconductor chips in wiring boards, connections within semiconductor chips, etc. It has been desired in recent years. For this reason, it is considered that the transition from metal cables and metal wirings, which have been conventionally common, to optical transmission using an optical transmission medium such as an optical fiber or an optical waveguide is ideal.

  Moreover, recently, in order to transmit and receive large-capacity data at a higher speed, it is required to perform optical transmission using a multi-channel, small, and low-profile optical transmission medium. For this reason, various optical waveguide devices including an optical waveguide structure in which a plurality of optical waveguide portions are formed have been proposed (see, for example, Non-Patent Document 1). In addition, in order to perform optical transmission using a small and low-profile optical transmission medium, a technique for bending an optical fiber with a small radius (1 mm) has been developed (see, for example, Non-Patent Document 2). In this type of optical waveguide device or optical module, usually, a photoelectric conversion element (light emitting element or light receiving element) is mounted on a substrate, and the photoelectric conversion element has a plurality of optical function units having functions of light emission or light reception. Provided. The plurality of optical function units and the plurality of optical waveguide units (or optical fibers) constituting the optical waveguide structure are optically coupled to each other.

  For example, in Non-Patent Document 1, a photoelectric conversion element is mounted on the main surface of an optical waveguide structure formed by laminating a plurality of optical waveguide sections, and an optical path conversion section (specifically, at the end of each optical waveguide section). Discloses a structure in which each of the optical waveguide portions and the plurality of optical functional portions are optically coupled to each other by forming a 45 ° reflection surface. Non-Patent Document 2 discloses a structure in which an optical connector is formed using an optical fiber having a bending radius of 1 mm, and optical transmission using a small and low-profile optical transmission medium is possible. As another structure for optically coupling each optical waveguide section and each optical functional section, a photoelectric conversion element is mounted on the main surface of the optical waveguide structure in which a plurality of optical waveguide sections are arranged on the same plane. In addition, a structure in which optical path changing portions (specifically, 45 ° reflection surfaces) formed at the end portions of the respective optical waveguide portions and the respective optical function portions are arranged in a matrix shape is considered.

M. Shishikura, Y. Matsuoka, T. Ban, T. Shibata and A. Takahashi, A High-Coupling-Efficiency Multilayer Optical Printed Wiring Board with a Cube-Core Structure for High-Density Optical Interconnections, ECTC 2007 (Proceedings of Fifty- Seventh Electronic Components & Technology Conference), USA: IEEE: The Printing House, Inc, May 29-June 1, 2007, pp. 1275-1280 Masahito Morimoto, Katsuki Suematsu, R = 1mm 90 ° -Bent Multi-Mode Optical Fiber, OFC 2008 (Optical Fiber Communication Conference and Exposition and The National Fiber Optic Engineers Conference) Paper JThA44, USA, Optical Society of America: Omnipress, 2008 2 24th-28th of month

  However, the conventional techniques described in Non-Patent Documents 1 and 2 have the following problems. That is, in the prior art described in Non-Patent Document 1, since the optical waveguide exists over a plurality of layers, the optical waveguide portion and the optical function portion are separated as the lower-layer side optical waveguide portion is located. As a result, the loss due to the spread of light between the optical waveguide portion and the optical function portion increases, and the light transmission loss increases. In order to solve this problem, it is conceivable to prevent light scattering by using an optical component such as a lens. However, the number of components increases by the amount of the lens, leading to an increase in manufacturing cost.

  In the prior art described in Non-Patent Document 2, each optical waveguide portion and each optical functional portion can be brought into contact with each other for optical coupling, so that a light transmission loss can be reduced. However, since the bending radius of the optical waveguide portion cannot be further reduced (for example, less than 1 mm), the entire optical waveguide device becomes 1 mm or more in thickness, and further miniaturization is difficult.

  Therefore, as described above, a plurality of optical waveguide portions are formed on the same plane, an optical path conversion portion (specifically, a 45 ° reflection surface) is formed at the end of each optical waveguide portion, and the optical function portion is It is conceivable to optically couple with photoelectric conversion elements arranged in a matrix. In this way, the transmission loss of light can be reduced without bending the optical waveguide portion, so that the entire optical waveguide device can be made thin. However, in each general optical waveguide part arranged in parallel on the same plane, a 45 ° reflection surface is usually obtained by cutting the surface of the optical waveguide part into a V-shaped cross section using a dicing saw. It is formed. In this case, when the dicing saw is cut so as to cross the optical waveguide portion, a cutting margin is required, and therefore, there is a possibility that the dicing saw may cut to the adjacent optical waveguide portion.

  The present invention has been made in view of the above-described problems, and a first object thereof is to provide an optical waveguide device that has a small light transmission loss and can be surely reduced in thickness. A second object is to provide a method of manufacturing an optical waveguide device capable of forming an optical path changing unit relatively easily with respect to the optical waveguide unit.

  As means (means 1) for solving the above-mentioned problems, an optical light having a main surface and a back surface located on the opposite side of the main surface, a core serving as an optical path for transmitting an optical signal, and a clad surrounding the core. An optical waveguide structure in which a plurality of waveguide sections are formed on the same plane, and a plurality of optical function sections having at least one function of light emission and light reception in the optical function section installation surface, and the plurality of optical functions A photoelectric conversion element mounted on the main surface in a state in which the portion is directed to the core side, and in the optical waveguide device in which the same number of the optical waveguide portions and the optical functional portions exist, the optical waveguide portion An optical path conversion unit that converts a path of an optical signal propagating in the optical path is formed, and the optical path conversion unit is formed by a conical recess having an opening on the back surface and a reflection surface that is inclined with respect to the back surface. The photoelectric conversion element has a plurality of optical function unit groups in which the plurality of optical function units are arranged in a straight line at an equal pitch in the optical function unit installation surface, and the optical function unit group The plurality of optical function units constituting the optical function unit and the plurality of optical function units constituting the adjacent optical function unit group are arranged offset from each other along a direction orthogonal to the arrangement direction of the optical function unit group. There is an optical waveguide device characterized in that

  Therefore, according to the means 1, the plurality of optical waveguide portions constituting the optical waveguide structure are formed on the same plane, and the same number of optical waveguide portions as the optical functional portions of the photoelectric conversion element are present. For this reason, it becomes easy to bring all the optical waveguide parts close to a plurality of optical function parts. As a result, it is possible to reduce the loss due to the spread of the optical signal between the optical waveguide portion and the optical function portion. Accordingly, it is not necessary to prevent the spread of the optical signal by using an optical component such as a lens. Therefore, the increase in the number of components can be prevented, and the optical waveguide device can be manufactured at a low cost. Further, since the plurality of optical waveguide portions are formed on the same plane, the optical waveguide structure can be reduced in thickness, and as a result, the entire optical waveguide device can be reduced in thickness. Furthermore, the optical functional units constituting the adjacent optical functional unit groups are arranged offset from each other along a direction orthogonal to the arrangement direction of the optical functional unit groups. As a result, the optical functional units can be easily arranged at a fine pitch, so that the optical waveguide structure can be reduced in size, and as a result, the entire optical waveguide device can be reduced in size.

  The optical waveguide device includes an optical waveguide structure. The optical waveguide structure has a structure in which a plurality of optical waveguide portions having a core serving as an optical path through which an optical signal propagates and a clad surrounding the core are formed on the same plane. The optical waveguide structure may be organic or inorganic. For example, as a resin material used for an organic optical waveguide structure, polyimide resin such as fluorinated polyimide, epoxy resin, UV curable epoxy resin, PMMA (polymethyl methacrylate), deuterated PMMA, deuterium fluorine Examples thereof include acrylic resins such as modified PMMA and polyolefin resins. Both the material forming the core and the material forming the clad preferably have translucency. The material forming the core is set so that the refractive index is higher than that of the material forming the clad, for example, by about 2% (specifically, about 0.2% to 4.0%, usually about 10% at the maximum). Is done.

  The optical waveguide device includes one or more photoelectric conversion elements. The photoelectric conversion element is mounted on the main surface of the optical waveguide structure. As the mounting method, for example, there are a method such as wire bonding and flip chip bonding, and a method using an anisotropic conductive material. When the photoelectric conversion elements are roughly classified, a plurality of optical function units (light emitting units) having a light emitting function (light emitting units) in the optical function unit installation surface (that is, light emitting elements) and a plurality of optical functional units having a light receiving function ( Some of them have a light receiving part) in the optical function part installation surface (that is, a light receiving element). Specific examples of the light emitting element include a light emitting diode (LED), a semiconductor laser diode (LD), a surface emitting laser (VCSEL), and the like. These light emitting elements have a function of converting an inputted electric signal into an optical signal and then emitting the optical signal from a light emitting portion toward a predetermined portion of the optical waveguide structure. On the other hand, specific examples of the light receiving element include a pin photo diode (pin PD) and an avalanche photo diode (APD). These light receiving elements have a function of causing an optical signal emitted from a predetermined portion of the optical waveguide structure to be incident on the light receiving portion, converting the incident optical signal into an electric signal, and outputting the electric signal. Therefore, in order to perform signal transmission, it is necessary to optically couple the light emitting part of the light emitting element and the light receiving part of the light receiving element to the optical waveguide part. Examples of suitable materials used for the photoelectric conversion element include Si, Ge, InGaAs, GaAsP, and GaAlAs.

  By the way, the photoelectric conversion element has a plurality of rows of optical functional unit groups in the optical functional unit installation surface, and constitutes an optical functional unit constituting a specific optical functional unit group and an adjacent optical functional unit group. The optical function units are arranged offset from each other along a direction orthogonal to the arrangement direction of the optical function unit group. Accordingly, the optical path conversion unit of the optical waveguide unit corresponding to the optical functional unit constituting the specific optical functional unit group, and the optical path conversion of the optical waveguide unit corresponding to the optical functional unit constituting the adjacent optical functional unit group The parts are also offset from each other along the arrangement direction of the optical waveguide parts. In this case, for example, when an optical path changing portion is formed using a dicing saw or the like, the dicing saw needs a cutting margin for cutting and cuts so as to cross each optical waveguide portion. There is a possibility that a portion where the optical path changing portion is not formed in the waveguide portion is cut.

  Therefore, when the optical path conversion unit is configured in the optical waveguide, the optical path conversion unit is preferably configured by a conical recess, and the conical recess is formed by drilling using a processing drill having a conical tip. It is preferable. In this way, when forming the optical path changing part for a specific optical waveguide part, the possibility of damaging the adjacent optical waveguide part is reduced. That is, the conical concave portion can be formed relatively easily with respect to an arbitrary place of the optical waveguide portion.

  The offset amount by which the plurality of optical function units configuring the optical function unit group and the plurality of optical function units configuring the adjacent optical function unit group are offset from each other is less than half of the pitch of the plurality of optical function units existing. In particular, it is more preferably 50 μm or more and half or less of the pitch. This makes it easier to separate the plurality of optical function units constituting the optical function unit group and the plurality of optical function units constituting the adjacent optical function unit group, so that the optical waveguide corresponding to the optical function unit is provided. It becomes easy to form the part. When the offset amount is less than 50 μm, even if the optical waveguide portion is formed corresponding to the optical function portion, the optical waveguide portions are likely to interfere with each other. Moreover, when processing the conical recess, the core of the adjacent optical waveguide is likely to be cut and damaged.

  In addition, it is preferable that the tip (deepest portion) of the conical recess is located between the core and the photoelectric conversion element connection wiring. Specifically, the conical recess may be positioned at the boundary between the optical waveguide portion and the photoelectric conversion element connection wiring, or between the core and the photoelectric conversion element connection wiring. It may be located in the cladding. In this case, since the conical recess penetrates the core, the path of the optical signal propagating through the core can be reliably changed by the formed conical recess. Moreover, when forming a conical recessed part with a processing drill, damage to the photoelectric conversion element connection wiring resulting from the contact of the processing drill can be prevented.

  Further, a photoelectric conversion element connection wiring is formed on the main surface, and at least a part of the photoelectric conversion element connection wiring is located within a range that is behind the conical recess formation region on the main surface, and the photoelectric conversion It is preferable that the connection portion between the element connection wiring and the photoelectric conversion element is located. In this way, the photoelectric conversion elements can be arranged in a small area, which is effective for downsizing the photoelectric conversion elements. Moreover, since the area | region which a photoelectric conversion element protrudes from said range can be made small, the space | interval of the optical waveguide parts in which the conical recessed part was formed can be narrowed. As a result, the size of the optical waveguide structure, and thus the entire optical waveguide device, can be reduced.

  The photoelectric conversion element connection wiring is formed of, for example, a conductive metal. Although it does not specifically limit as a conductive metal, For example, 1 type, or 2 or more types of metals selected from copper, gold, silver, platinum, palladium, nickel, tin, lead, titanium, tungsten, molybdenum, tantalum, niobium, etc. Can be mentioned. Examples of the conductive metal composed of two or more metals include solder that is an alloy of tin and lead. Lead-free solder (for example, Sn-Ag solder, Sn-Ag-Cu solder, Sn-Ag-Bi solder, Sn-Ag-Bi-Cu solder) as a conductive metal composed of two or more metals Of course, Sn—Zn solder, Sn—Zn—Bi solder, etc.) may be used.

  Moreover, as another means (means 2) for solving the above-mentioned problem, it is a method for manufacturing the optical waveguide device according to the above means 1, and an optical waveguide part preparation step for preparing the optical waveguide part, There is a method of manufacturing an optical waveguide device including a recess forming step of forming the conical recess by drilling from the back surface side using a processing drill having a conical tip.

  Therefore, the means 2 does not form a light path changing part using a dicing saw for a plurality of light waveguide parts formed on the same plane, but uses a processing drill to form a conical shape that is a light path changing part. A recess is formed. Unlike the dicing saw that performs processing that cuts in the plane direction of the optical waveguide structure perpendicular to the light propagation direction in the optical waveguide, this processing drill digs in the thickness direction of the optical waveguide structure. Since drilling is performed, the possibility of processing to the adjacent optical waveguide portion is reduced when the conical recess is formed. That is, a conical recess serving as an optical path changing portion can be formed relatively easily in an arbitrary place of the optical waveguide portion. Moreover, since it is possible to perform drilling with a processing drill using a commonly used drilling machine, the mass productivity of the optical waveguide device is improved.

  Hereafter, the manufacturing method of an optical waveguide device is demonstrated along a process.

  First, the optical waveguide part preparation process which prepares an optical waveguide part is performed. Here, the optical waveguide section preparation step includes, for example, a core formation step for forming a core, a clad formation step for forming a clad, and a wiring formation step for forming a photoelectric conversion element connection wiring on the main surface. Yes. In addition, as a method for forming the photoelectric conversion element connecting wiring in the wiring forming step, etching, plating, printing and baking of metal paste, sticking of metal foil, sputtering, vapor deposition, ion plating, and the like can be given.

  In the subsequent recess forming step, the conical recess is formed by drilling from the back side of the optical waveguide structure using a drill for processing having a conical tip. In the recess forming step, it is preferable to form the conical recess so as to penetrate the core using a machining drill. In this case, the path of the optical signal propagating through the core can be reliably converted and output by the conical recess formed through the core. Moreover, an optical signal can be reliably incident in the core. Furthermore, damage to the photoelectric conversion element connection wiring due to the contact of the machining drill can be prevented.

1 is a schematic cross-sectional view showing an optical waveguide device of the present embodiment. The schematic plan view which shows an optical waveguide device. Explanatory drawing which shows the manufacturing method of an optical waveguide device. Explanatory drawing which shows the manufacturing method of an optical waveguide device. The schematic sectional drawing which shows the optical waveguide structure in other embodiment. The schematic sectional drawing which shows the optical waveguide structure in other embodiment. The schematic sectional drawing which shows the optical waveguide structure in other embodiment. The schematic sectional drawing which shows the optical waveguide structure in other embodiment.

  Hereinafter, an embodiment embodying the present invention will be described in detail with reference to the drawings.

  1 and 2 show an optical waveguide device 10 of the present embodiment. The optical waveguide device 10 includes an optical waveguide structure 20 having a main surface 21 and a back surface 22 located on the opposite side of the main surface 21. The optical waveguide structure 20 is supported from the back surface 22 side by a ceramic wiring substrate (not shown). The ceramic wiring board may be a multilayer ceramic wiring board formed by laminating a plurality of ceramic layers, or may be a single-layer ceramic wiring board made of only one ceramic layer. Moreover, the ceramic wiring board may be omitted.

  Further, on the main surface 21 of the optical waveguide structure 20, photoelectric conversion element connection wiring 41 is formed. The photoelectric conversion element connection wiring 41 is formed by pasting a metal foil (not shown) on the main surface 21 using an adhesive and then patterning the pasted metal foil. A plurality of solder bumps 42 are disposed on the surface of the photoelectric conversion element connection wiring 41.

  As shown in FIGS. 1 and 2, twelve optical waveguide portions 23 are formed on the same plane in the optical waveguide structure 20. Each optical waveguide portion 23 has a rectangular shape with a core 25 having a width of 50 μm and an overall thickness of 100 μm, and is formed to extend linearly and in parallel. Each optical waveguide portion 23 includes a lower cladding 24 having a thickness of 25 μm, a core 25 having a thickness of 50 μm, and an upper cladding 26 having a thickness of 25 μm, and the total thickness is 100 μm. The core 25 is a portion that substantially becomes an optical path through which an optical signal propagates, and is surrounded by a lower clad 24 and an upper clad 26. In the case of the present embodiment, transparent polymer materials having different refractive indexes are used for the core 25 and the clads 24 and 26. More specifically, the material forming the core 25 is refracted by about 2% (specifically, usually about 0.2% to 4.0%, about 10% at the maximum) than the material forming the clads 24 and 26. The rate is high.

  As shown in FIG. 1, optical path conversion sections 31 that convert the path of an optical signal propagating in the optical path are formed at both ends of each optical waveguide section 23. The optical path conversion unit 31 is configured by a conical recess 33 that opens at the back surface 22 of the optical waveguide structure 20. The conical recess 33 is formed by drilling using a machining drill 51 (see FIG. 3) having a conical tip. The conical recess 33 penetrates the lower clad 24 and the core 25 and has a tip between the core 25 and the photoelectric conversion element connection wiring 41, specifically, the optical waveguide section 23 and the photoelectric conversion element connection. It is located at the boundary with the wiring 41. Furthermore, the conical recess 33 has a reflection surface 32 inclined on the back surface 22 at an angle of 45 ° on the inner surface. As a result, an optical path changing mirror that reflects light at an angle of 90 ° is configured. The inner diameter at the open end of the conical recess 33 is twice as large as the thickness of the optical waveguide portion 23 (200 μm in this embodiment). Then, a part of the photoelectric conversion element connection wiring 41 is located in a range on the main surface 21 of the optical waveguide structure 20 on the back side of the formation region R1 of the conical recess 33.

  As shown in FIGS. 1 and 2, the optical waveguide device 10 includes a VCSEL 43 that is a kind of photoelectric conversion element (light emitting element). The VCSEL 43 has a substantially rectangular flat plate shape of 2.5 mm in length and 1.5 mm in width, and includes twelve light-emitting portions 44 (light function portions) having a light emission function as light-emitting portion installation surfaces 45 (light function portion installation surfaces). Have in. That is, the same number of optical waveguide portions 23 and light emitting portions 44 exist. The VCSEL 43 is mounted on the main surface 21 with each light emitting unit 44 facing the core 25 side. Each light emitting unit 44 emits laser light (optical signal) having a predetermined wavelength in a direction orthogonal to the main surface 21 (downward in FIG. 1). A plurality of terminals (not shown) of the VCSEL 43 are flip-chip connected to the solder bumps 42 disposed on the surface of the photoelectric conversion element connection wiring 41. And the connection part of the photoelectric conversion element connection wiring 41 and the VCSEL 43 is located within a range on the back side of the above-described formation region R1.

  As shown in FIG. 2, the VCSEL 43 includes three light emitting unit groups 46, 47, and 48 (light functional unit groups) in which four light emitting units 44 are arranged in a straight line at an equal pitch. It is in the installation surface 45. In addition, the pitch L1 of the light emission part 44 which comprises each light emission part group 46-48 is each set to 500 micrometers. In addition, the light emitting unit 44 constituting the first light emitting unit group 46 and the light emitting unit 44 constituting the second light emitting unit group 47 adjacent to the light emitting unit group 46 are arranged in the light emitting unit groups 46 to 48. They are arranged offset from each other along a direction (vertical direction in FIG. 2) perpendicular to the direction (horizontal direction in FIG. 2). Note that the offset amount L2 that the light emitting unit 44 constituting the light emitting unit group 46 and the light emitting unit 44 constituting the light emitting unit group 47 are offset from each other is 50 μm or more and half or less of the pitch L1 (500 μm) (160 μm in this embodiment) : About 1/3 of the pitch L1). As a result, it is possible to reduce the size and increase the density as compared with the case where all the light emitting units 44 are arranged on a straight line. Similarly, the light emitting unit 44 constituting the light emitting unit group 47 in the second row and the light emitting unit 44 constituting the light emitting unit group 48 in the third row adjacent to the light emitting unit group 47 are also included in the light emitting unit groups 46 to 48. They are offset from each other along a direction orthogonal to the arrangement direction. The offset amount L2 at which the light emitting part 44 constituting the light emitting part group 47 and the light emitting part 44 constituting the light emitting part group 48 are offset from each other is also set to 50 μm or more and half or less of the pitch L1. In addition, below each light emission part 44, the conical recessed part 33 formed in one edge part of the optical waveguide part 23 exists, respectively.

  The optical waveguide device 10 shown in FIGS. 1 and 2 includes a photodiode (not shown) which is a kind of photoelectric conversion element (light receiving element). The photodiode of this embodiment has a configuration that is substantially the same as that of the VCSEL 43. That is, this photodiode has twelve light receiving parts (light functional parts) having a light receiving function in a light receiving part installation surface (light functional part installation surface). That is, the same number of optical waveguide portions 23 and light receiving portions exist. The photodiode is mounted on the main surface 21 with each light receiving portion facing the core 25, and each light receiving portion is a laser directed in a direction orthogonal to the main surface 21 (upward in FIG. 1). It is configured to easily receive light (optical signal). A plurality of terminals (not shown) of the photodiode are flip-chip connected to the solder bumps arranged on the surface of the photoelectric conversion element connection wiring 41.

  Further, the photodiode has three rows of light receiving unit groups (optical function unit groups) in which four light receiving units are arranged on a straight line and at equal pitches in the light receiving unit installation surface. In addition, the light receiving parts constituting the specific light receiving part group and the light receiving parts constituting the adjacent light receiving part group are arranged offset from each other along the direction orthogonal to the arrangement direction of the light receiving part groups. Note that the offset amount by which the light receiving parts constituting the adjacent light receiving part groups are offset from each other is set to 50 μm or more and less than half the pitch (500 μm) of the light receiving parts (160 μm in this embodiment). A conical recess 33 formed at the other end of the optical waveguide portion 23 exists below each light receiving portion.

  Further, a driver IC (not shown) for driving the VCSEL 43 and a receiver IC (not shown) for driving the photodiode are joined to each solder bump disposed on the surface of the photoelectric conversion element connection wiring 41. Yes. Accordingly, the driver IC and the VCSEL 43 are electrically connected via the photoelectric conversion element connection wiring 41 and the like, and the photodiode and the receiver IC are electrically connected via the photoelectric conversion element connection wiring 41 and the like. Connected.

  A general operation of the optical waveguide device 10 configured as described above will be briefly described.

  The VCSEL 43 and the photodiode operate via a circuit device (not shown) connected to the wiring board or the wiring. When an electrical signal is output from the driver IC to the VCSEL 43, the VCSEL 43 converts the input electrical signal into an optical signal, and then directs the optical signal toward the reflection surface 32 of the optical path conversion unit 31 from the light emitting unit 44 as laser light. Exit. The laser light emitted from the light emitting unit 44 enters from the main surface 21 side of the optical waveguide structure 20 and reaches the reflection surface 32. The laser beam that has reached the reflecting surface 32 changes its traveling direction by 90 ° and enters one end of the core 25. The laser beam that has propagated through the core 25 and has reached the other end is reflected by the reflecting surface of the optical path changing unit provided there, and again changes the traveling direction by 90 °. For this reason, the laser light is emitted from the main surface 21 side of the optical waveguide structure 20 and enters the light receiving portion of the photodiode. Then, the photodiode converts the optical signal into an electric signal and outputs it to the receiver IC. The receiver IC amplifies it and outputs it to the substrate.

  Next, a method for manufacturing the optical waveguide device 10 will be described with reference to the drawings.

  First, an optical waveguide part preparation step is performed, and a plurality of optical waveguide parts 23 are prepared by a conventionally known technique and prepared in advance. The optical waveguide section preparation step includes an upper clad forming step, a core forming step, a lower clad forming step, and a wiring forming step.

In the upper clad forming step, the upper clad 26 in each optical waveguide portion 23 is formed. For example, first, an epoxy compound [alicyclic epoxy compound (EHPE3150 manufactured by Daicel Chemical Industries, Ltd.) is 99.5% by mass, and a polymerization initiator (photoacid generator SP172 manufactured by Asahi Denka Kogyo Co., Ltd.) is included. A curable composition containing 0.5% by mass] and a solvent (methyl ethyl ketone) are mixed and dissolved to prepare a mixed solution having a solid content of 78%. Then, the obtained mixed solution is apply | coated by the casting method on a support body (PET film of thickness 38 micrometers). Next, drying is performed for 30 minutes while heating to 70 ° C. As a result, the solvent is removed, and an uncured film for clad formation is obtained. Then, the uncured film is transferred by laminating the uncured film on a predetermined substrate such as a wiring board or metal foil. Specifically, a pressure of 0.5 MPa is applied in the stacking direction of the substrate and the uncured film while being heated to 40 ° C. to 50 ° C. Furthermore, after peeling the PET film, drying is performed for 30 minutes in a state heated to 70 ° C. As a result, the solvent is removed, and the uncured upper clad 26 is obtained. Instead of the above method, it is also possible to form the uncured upper clad 26 by applying a clad forming liquid by a known method such as spin coating and drying. Thereafter, the upper clad 26 in an uncured state is exposed using an ultraviolet lamp (exposure amount 2000 mJ / cm ² , about 7 minutes), post-baking (120 ° C., 30 minutes), and main curing (150 ° C., 1 minute). Time), a fully cured upper cladding 26 is obtained. As described above, the manufacturing method for forming the optical waveguide on the metal foil has the upper clad 26 formed of the adhesive as compared with the manufacturing method for bonding the metal foil using the adhesive after the optical waveguide structure 20 is completed. Doubles as That is, the step of forming the adhesive layer separately from the upper clad 26 can be omitted, which is effective for cost reduction.

In the subsequent core formation process, the core 25 in each optical waveguide part 23 is formed. For example, first, epoxy compound [aromatic epoxy compound (Epicoat 1001 manufactured by Japan Epoxy Resin Co., Ltd.) is 44.5% by mass, alicyclic epoxy compound (EHPE3150 manufactured by Daicel Chemical Industries, Ltd.) is 55. A curable composition containing 0.0% by mass and 0.5% by mass of a polymerization initiator (photoacid generator SP172 manufactured by Asahi Denka Kogyo Co., Ltd.) is prepared. Next, this curable composition and a solvent (methyl ethyl ketone) are mixed and dissolved to prepare a mixed solution having a solid content of 78%. Then, the obtained mixed solution is apply | coated by the casting method on a support body (for example, PET film with a thickness of 38 micrometers). Next, drying is performed for 30 minutes while heating to 70 ° C. As a result, the solvent is removed, and an uncured film for core formation is obtained. The obtained uncured film is laminated on the upper clad 26 and laminated. Specifically, a pressure of 0.5 MPa is applied in the lamination direction of the upper clad 26 and the uncured film while being heated to 40 ° C. to 50 ° C. Furthermore, after peeling off the PET film, the core 25 in an uncured state is formed by drying for 30 minutes while heating to 70 ° C. Thereafter, a photomask having a predetermined pattern is disposed on the uncured core 25, and in this state, exposure using an ultraviolet lamp (exposure amount: 500 mJ / cm ² , about 2 minutes) and post-baking (120 (C, 30 minutes). Thereby, the exposed part will be in a temporary hardening state. Next, the development (30 seconds) using 2-methoxyethanol is performed to remove the uncured resin, and the residue of the uncured resin is washed and removed using isopropyl alcohol (IPA). The core 25 in the state is patterned. Then, the completely cured core 25 is obtained by performing the main curing (150 ° C., 1 hour). Instead of forming the core 25 by performing exposure and development, the core 25 may be formed by using another method depending on the material. For example, the core 25 is formed by performing photobleaching. Also good.

In the lower clad formation step, the lower clad 24 in each optical waveguide portion 23 is formed. Here, the same uncured film (uncured film for forming the lower clad) used in the upper clad forming step is prepared. Then, the obtained uncured film is laminated on the core 25 and the upper clad 26 and heated to 40 ° C. to 50 ° C., and 0.5 MPa in the laminating direction of the upper clad 26, the core 25 and the uncured film. Apply pressure. Thereafter, after peeling off the PET film, drying is performed for 30 minutes in a state of being heated to 70 ° C., whereby the uncured lower clad 24 is formed. Next, the uncured lower clad 24 is exposed using an ultraviolet lamp (exposure amount 2000 mJ / cm ² , about 7 minutes), post-baking (120 ° C., 30 minutes), and main curing (150 ° C., 1 hour), a completely cured lower clad 24 is obtained, and the optical waveguide structure 20 in which a plurality of optical waveguide portions 23 are formed is completed.

  When the wiring substrate is not used as the base in the above-described optical waveguide structure 20 forming process, wiring is formed after the lower cladding forming process, after the core forming process, and after the upper cladding forming process (wiring forming process). . In the wiring formation step, photoelectric conversion element connection wiring 41 and the like are formed on the main surface 21 of the optical waveguide structure 20. For example, first, a metal foil (not shown) is attached to the main surface 21 of the optical waveguide structure 20 using an adhesive. Here, the metal foil used as the base when forming the optical waveguide portion 23 may be used as it is. Next, a wiring pattern is formed from this metal foil. As a forming method, a conventionally well-known method can be used, such as partially protecting the metal foil with a photoresist and then removing unnecessary metal foil by etching. As a result, the photoelectric conversion element connection wiring 41 is formed. Then, you may form the soldering resist layer (not shown) which formed the opening in the part which mounts the solder bump for connecting a photoelectric conversion element.

  In the subsequent recess forming step, the machining drill 51 is pressed against the back surface 22 of the optical waveguide portion 23, and drilling is performed while rotating the machining drill 51 (see FIG. 3). Thereafter, the distal end portion 52 (a portion having a 45 ° inclined surface) of the machining drill 51 enters the optical waveguide portion 23. Then, when the tip of the processing drill 51 reaches the boundary portion between the optical waveguide portion 23 and the photoelectric conversion element connection wiring 41, the drilling by the processing drill 51 is finished, whereby the reflection surface 32 of 45 °. The conical recessed part 33 which has is formed (refer FIG. 4). In this way, by controlling the depth of drilling, damage to the photoelectric conversion element connection wiring 41 by the machining drill 51 is prevented. In addition, the length of the front-end | tip part 52 should just be a magnitude | size which can form the 45-degree conical recessed part 33 in the core 25 of the optical waveguide part 23. FIG.

  Thereafter, the optical waveguide structure 20 is inverted and disposed so that the main surface 21 is positioned upward and the back surface 22 is positioned downward. In this state, a plurality of solder bumps 42 are formed on the photoelectric conversion element connection wiring 41. Next, the VCSEL 43, the driver IC, the photodiode, and the receiver IC are mounted on the photoelectric conversion element connection wiring 41, respectively. Then, solder reflow is performed at a predetermined temperature and a predetermined time to melt the solder bumps, and the VCSEL 43, the driver IC, the photodiode, and the receiver IC are joined to the photoelectric conversion element connection wiring 41, whereby the optical waveguide device 10 is completed. Note that the VCSEL 43, the driver IC, the photodiode, and the receiver IC may be mounted by performing heating at the same time as the alignment by the flip chip bonder instead of the solder reflow.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) According to the optical waveguide device 10 of the present embodiment, the plurality of optical waveguide portions 23 constituting the optical waveguide structure 20 are formed on the same plane, and the optical waveguide portion 23 is the light emitting portion 44 or the photo of the VCSEL 43. There are the same number as the light receiving portions of the diode. For this reason, it becomes easy to bring all the optical waveguide parts 23 close to the plurality of light emitting parts 44 and the plurality of light receiving parts. As a result, loss due to the spread of the optical signal between the optical waveguide portion 23 and the light emitting portion 44 or between the optical waveguide portion 23 and the light receiving portion can be reduced. Accordingly, it is not necessary to prevent the spread of the optical signal by using an optical component such as a lens. Therefore, the increase in the number of components can be prevented, and the optical waveguide device 10 can be manufactured at a low cost. Further, since the plurality of optical waveguide portions 23 are formed on the same plane, the optical waveguide structure 20 can be reduced in thickness, and as a result, the entire optical waveguide device 10 can be reduced in thickness.

  (2) In the present embodiment, the VCSEL 43 includes the light emitting unit groups 46 to 48 in the light emitting unit installation surface 45. For example, the VCSEL 43 configures the light emitting unit 44 and the light emitting unit group 47 that constitute the light emitting unit group 46. The light emitting units 44 are arranged offset from each other along a direction (vertical direction in FIG. 2) perpendicular to the arrangement direction of the light emitting unit groups 46 to 48 (horizontal direction in FIG. 2). Accordingly, the optical path conversion unit 31 of the optical waveguide unit 23 located below the light emitting unit 44 constituting the light emitting unit group 46 and the optical path of the optical waveguide unit 23 located below the light emitting unit 44 constituting the light emitting unit group 47. The conversion units 31 are also arranged offset from each other along the arrangement direction (vertical direction in FIG. 2) of the optical waveguide units 23. In this case, for example, when the optical path changing unit 31 is formed using a dicing saw or the like, the dicing saw cuts so as to cross each optical waveguide unit 23, so that the optical path changing unit 31 is adjacent to the adjacent optical waveguide unit 23. There is a possibility of cutting a portion that is not formed. In this case, the core 25 may be damaged, and optical signal transmission may be impossible.

  Therefore, in the present embodiment, the optical path conversion unit 31 is configured by the conical recess 33, and the conical recess 33 is formed by drilling using the processing drill 51 having a conical tip. In this case, when forming the conical recessed part 33 with respect to the specific optical waveguide part 23, possibility that the adjacent optical waveguide part 23 will be processed becomes small. That is, the conical concave portion 33 can be formed relatively easily in any place of the optical waveguide portion 23.

  (3) The prior art described in Japanese Patent Application Laid-Open No. 2007-183469 discloses a technique for forming a conical recess by drilling. However, since the surface where the conical recess is opened and the mounting surface of the photoelectric conversion element (VCSEL and photodiode) are the same, wiring necessary for connecting the photoelectric conversion element is processed during drilling, and photoelectric conversion is performed. There is a possibility that the element cannot be mounted. Therefore, the conical recess 33 of the present embodiment is opened at the back surface 22 located on the opposite side of the main surface 21 instead of the main surface 21 which is a mounting surface of the photoelectric conversion elements (VCSEL 43 and photodiode). As a result, when the conical recess 33 is formed, processing of the photoelectric conversion element connection wiring 41 by the processing drill 51 is prevented, so that the connection portion between the photoelectric conversion element connection wiring 41 and the photoelectric conversion element is conical. Without being concerned about the presence of the concave portion 33, it can be freely set including the range of the formation region R1 of the conical concave portion 33, and the photoelectric conversion element can be mounted regardless of the size and structure.

  (4) Since the optical path conversion unit 31 of the present embodiment is configured by the conical recess 33, the conical recess 33 is used as a position reference when aligning the optical axis between the photoelectric conversion element and the optical waveguide unit 23. be able to. As a result, the optical axis alignment between the photoelectric conversion element and the optical waveguide portion 23 can be performed more accurately, and both can be optically coupled with high accuracy.

  (5) Papers of IEEE Transactions of Advanced Packaging (vol. 32, no. 2, pp. 509-516, MAY 2009), JP 2008-158471 A, Proceedings of International Society ECTC 2008 (pp. 238-243) In the prior art described in the above, laser processing is performed by irradiating a laser beam at an angle of about 45 ° with respect to a predetermined portion of the optical waveguide portion, and the inner wall surface of the hole formed by the laser processing is reflected on the reflecting surface (mirror) The technique utilized as is disclosed. According to these prior arts, a reflecting surface can be formed at an arbitrary place without cutting the adjacent optical waveguide part, so that the optical path conversion of the optical waveguide part adjacent to the optical path conversion part of the specific optical waveguide part is possible. The optical path conversion part (reflective surface) can be reliably formed even when the part is offset and disposed along the arrangement direction of the optical waveguide part. However, irradiating a laser beam from obliquely above the optical waveguide portion is different from a method for arranging a processing target in a normal laser processing machine. As a result, since it is difficult to dispose the optical waveguide and the laser light source, the mass productivity of the optical waveguide device is reduced and the apparatus cost is increased. Further, since the formed reflection surface becomes rough, loss due to light scattering increases, and light transmission loss increases. On the other hand, in this embodiment, the conical recessed part 33 (optical path changing part 31) is formed using the drill 51 for a process with the normal arrangement | positioning method of the process target. As a result, since the conical recess 33 can be easily formed, the mass productivity of the optical waveguide device 10 is improved. Further, since the reflecting surface 32 in the conical recess 33 is smooth, loss due to light scattering is reduced, and light transmission loss is reduced.

  In addition, you may change this embodiment as follows.

  In the optical waveguide structure 20 of the above embodiment, the conical recess 33 has the reflecting surface 32, and the inside of the conical recess 33 is a space. However, it may be an optical waveguide structure 60 in which a thin film 62 made of a metal (gold, silver, copper, aluminum, chromium, titanium, rhodium, nickel, etc.) capable of reflecting light is deposited on the reflecting surface 61 (FIG. 5). reference). Further, a dielectric multilayer film capable of reflecting light may be formed. In this way, the reflectance of the optical signal reflected by the reflecting surface 61 is improved, so that the light transmission loss is further reduced. Alternatively, the optical waveguide structure 70 may be filled with a resin 72 for protecting the thin film 62 after the thin film 62 is deposited inside the conical recess 71 (see FIG. 6). Further, the gap between the optical waveguide structure 70 and the VCSEL 43 may be sealed with an underfill that can transmit light having a wavelength to be used.

  In the optical waveguide structure 20 of the above embodiment, the tip of the conical concave portion 33 is located at the boundary portion between the optical waveguide portion 23 and the photoelectric conversion element connection wiring 41. However, as long as the 45 ° reflection surface can be formed in the core 25, the conical recess 81 may be the optical waveguide structure 80 positioned in the upper clad 82 (see FIG. 7). Moreover, the optical waveguide structure 90 which the conical recessed part 91 opens in both the main surface 92 and the back surface 93 may be sufficient (refer FIG. 8).

  In the above embodiment, after the metal foil is attached to the main surface 21 of the optical waveguide structure 20 using an adhesive, the photoelectric conversion element connection is performed by a conventionally known patterning method using a photoresist, etching, or the like. Wiring 41 was formed. However, the method for forming the photoelectric conversion element connection wiring 41 may be changed. For example, the photoelectric conversion element connection wiring 41 may be formed by forming a metal layer by performing sputtering or vapor deposition on the main surface 21 and then processing the metal layer by a conventionally known processing technique. In addition, you may make it make the thickness and material of a metal layer the optimal state for mounting of a photoelectric conversion element by performing electroless plating, electrolytic plating, etc. with respect to the processed metal layer. Alternatively, after forming the photoelectric conversion element connection wiring 41 on a separately prepared substrate (for example, PET film), the formed photoelectric conversion element connection wiring 41 may be transferred and bonded onto the main surface 21. The substrate is removed after transfer or adhesion.

  In the above embodiment, the conical recess 33 is formed after the photoelectric conversion element connection wiring 41 is formed on the main surface 21 of the optical waveguide structure 20. However, the photoelectric conversion element connection wiring 41 may be formed on the main surface 21 after the conical recess 33 is formed.

  In the above embodiment, the tip of the conical recess 33 is located at the boundary between the optical waveguide portion 23 and the photoelectric conversion element connection wiring 41. In other words, the end of the photoelectric conversion element connection wiring 41 is located at the center of the conical recess 33 on the main surface 21. However, the end of the photoelectric conversion element connection wiring 41 may be located on the outer peripheral side of the center of the conical recess 33 as long as it can be connected to the VCSEL 43 via the solder bumps 42.

  The optical waveguide device 10 of the above embodiment includes an optical waveguide structure 20, a VCSEL 43 mounted on the main surface 21 of the optical waveguide structure 20, and a ceramic wiring board that supports the optical waveguide structure 20 from the back surface 22 side. It had the structure provided with. However, the optical waveguide device may have other structures. For example, instead of supporting the optical waveguide structure 20 with a ceramic wiring substrate, a resin wiring substrate may be interposed between the optical waveguide structure 20 and the VCSEL 43. More specifically, the optical waveguide structure 20 is attached on the back surface of the resin wiring board. In addition, the VCSEL 43 is mounted on the main surface of the resin wiring board with the plurality of light emitting portions 44 facing the core 25 side of the optical waveguide structure 20. Further, an optical waveguide structure portion that guides the optical signal emitted from the light emitting portion 44 to the core 25 is formed through the resin wiring board. In this case, in the optical waveguide structure portion formed in a penetrating manner, an end portion on the side where the photoelectric conversion element including the optical function portion is not mounted, that is, an input / output portion of light to the resin wiring board is replaced with a new optical function. Can be considered a part. Therefore, even if a resin wiring substrate is interposed between the optical waveguide portion and the photoelectric conversion element, it can be said that the structure equivalent to that in FIG. 1 is provided. The resin wiring board may be a multilayer resin wiring board formed by laminating a plurality of resin insulating layers, or may be a single-layer resin wiring board consisting of only one resin insulating layer. Further, the resin wiring substrate may be a build-up multilayer wiring substrate having a build-up layer formed by alternately laminating resin insulating layers and conductor layers on the surface layer of the core substrate.

  Next, the technical ideas grasped by the embodiment described above are listed below.

  (1) In the above means 1, the photoelectric conversion element connection wiring is formed on the main surface, and the photoelectric conversion element connection wiring is within a range on the back side of the formation area of the conical recess on the main surface. At least a portion is located, and a connection portion between the photoelectric conversion element connection wiring and the photoelectric conversion element is located, and the conical recess has a tip at the optical waveguide portion and the photoelectric conversion element connection wiring. An optical waveguide device characterized in that it is located at a boundary portion between and an optical waveguide device.

  (2) In the above means 1, the clad comprises a lower clad and an upper clad disposed on the core, and the conical recess penetrates the lower clad and the core, and a tip is the core. And an optical waveguide device, wherein the optical waveguide device is located between the wiring for connecting photoelectric conversion elements.

DESCRIPTION OF SYMBOLS 10 ... Optical waveguide device 20, 60, 70, 80, 90 ... Optical waveguide structure 21, 92 ... Main surface 22, 93 ... Back surface 23 ... Optical waveguide part 24 ... Lower clad 25 as a clad ... Core 26, 82 ... Cladding Upper clad 31 as ... Optical path conversion parts 32, 61 ... Reflecting surfaces 33, 71, 81, 91 ... Conical concave part 41 ... Photoelectric conversion element connection wiring 43 ... VCSEL as a photoelectric conversion element
44 ... Light emitting part 45 as an optical function part ... Light emitting part installation surfaces 46, 47, 48 as an optical function part installation surface ... Light emitting part group 51 as an optical function part group ... Processing drill L1 ... Pitch L2 ... Offset amount R1 ... Formation area of conical recess

Claims (7)

An optical waveguide structure having a main surface and a back surface positioned on the opposite side of the main surface, and a plurality of optical waveguide portions each having a core serving as an optical path through which an optical signal propagates and a clad surrounding the core are formed on the same plane When,
A plurality of optical function units having at least one function of light emission and light reception are provided in the optical function unit installation surface, and the plurality of optical function units are mounted on the main surface in a state facing the core side. In the optical waveguide device provided with the photoelectric conversion element, and the optical waveguide portion and the optical functional portion are present in the same number,
An optical path conversion unit that converts a path of an optical signal propagating in the optical path is formed in the optical waveguide unit,
The optical path changing unit is configured by a conical recess having an opening on the back surface and a reflecting surface inclined with respect to the back surface,
The photoelectric conversion element includes a plurality of rows of optical function units formed by arranging the plurality of optical function units on a straight line at an equal pitch, and constitutes the optical function unit group. The plurality of optical function units and the plurality of optical function units constituting the adjacent optical function unit group are arranged offset from each other along a direction perpendicular to the arrangement direction of the optical function unit group. An optical waveguide device characterized by the above.   2. The optical waveguide device according to claim 1, wherein the conical recess is formed by drilling using a processing drill having a conical tip. A photoelectric conversion element connection wiring is formed on the main surface,
In the main surface, at least part of the photoelectric conversion element connection wiring is located within a range that is behind the formation region of the conical recess, and the connection between the photoelectric conversion element connection wiring and the photoelectric conversion element The optical waveguide device according to claim 1, wherein the portion is located.   The optical waveguide device according to claim 3, wherein a tip of the conical recess is located between the core and the photoelectric conversion element connection wiring.   The offset amount by which the plurality of optical function units configuring the optical function unit group and the plurality of optical function units configuring the adjacent optical function unit group are offset from each other is half the pitch of the plurality of optical function units The optical waveguide device according to any one of claims 1 to 4, wherein: A method of manufacturing the optical waveguide device according to any one of claims 1 to 5,
An optical waveguide part preparing step of preparing the optical waveguide part;
A method of manufacturing an optical waveguide device, comprising: a recess forming step of forming the conical recess by drilling from the back side using a processing drill having a conical tip. The optical waveguide section preparing step includes a core forming step for forming the core, a clad forming step for forming the clad, and a photoelectric conversion element connecting surface on the main surface after the core forming step and after the clad forming step. A wiring forming process for forming wiring,
The said recessed part formation process forms the said cone-shaped recessed part by making the front-end | tip of the said drill for drill reach | attain between the said core and the said photoelectric conversion element connection wiring. Manufacturing method of optical waveguide device.

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