JP2015194689A - Optical fiber mounting component, optical module, and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber mounting component that can protect a laser device mounted on a substrate and perform highly accurate alignment of the laser device and the optical fiber.SOLUTION: An optical fiber mounting component 50 is a silicon-made mounting component 50 bonded to a mounting substrate 10 on which a laser device 20 is mounted to be joined so as to optically couple the laser device 20 to an optical fiber 40. The optical fiber mounting component 50 comprises: a groove part 51 for fixing the optical fiber so that a core of the optical fiber is positioned in a predetermined depth with respect to a bonding surface 53 with the mounting substrate; and a recess 52 linked to the groove part 51, for receiving the laser device 20 therein. A depth perpendicular to the bonding surface 53 is set to be a depth capable of detecting the position of the laser device 20 by a transmitted image of infrared when the bonding surface 53 is brought into contact with the mounting substrate 10 so as to store the laser device 20 in the recess 52.

Description

  The present invention relates to an optical fiber mounting component, an optical module, and a manufacturing method.

  In an optical module in which light from a laser element is directly incident on an optical fiber (that is, optically coupled), it is necessary to align the laser element and the optical fiber in order to increase the efficiency of optical coupling. In this alignment process, passive alignment that adjusts the relative position of the laser element and the optical fiber with reference to the alignment mark provided in advance and the optical output that emits the laser element and is coupled to the optical fiber are monitored. There is an active alignment that adjusts the relative position. In general, the alignment accuracy in the active alignment is higher than that in the passive alignment, but the manufacturing cost is increased because the alignment process takes time.

  Therefore, an optical module has been proposed that has a simple structure and can realize high optical coupling efficiency equivalent to that of conventional active alignment (see, for example, Patent Document 1). In the optical module of Patent Document 1, an LD mounting substrate in which an LD (laser diode) is mounted on the surface of a guide substrate provided with a guide groove for holding an optical fiber inside and a concave groove connected to a terminal end portion of the guide groove is provided. The LD is mounted so as to be accommodated in the groove. In this optical module, the vertical positioning of the optical fiber and the LD is performed by passive alignment, and the lateral positioning is performed by active alignment.

JP-A-10-311936

  However, in the optical module disclosed in Patent Document 1, it is difficult to align the LD and the optical fiber in the order of submicrons in the three directions x, y, and z. In order to increase the accuracy of alignment, it is desirable to finely adjust submicron order efficiently by active alignment after positioning as accurately as possible in micron order by passive alignment. In an optical module including a laser element, it is practically important to provide a cover for the laser element and take measures such as protection of the element and dust prevention.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical fiber mounting component capable of aligning the laser element and the optical fiber with higher accuracy while protecting the laser element mounted on the substrate. . It is another object of the present invention to provide an optical module that is smaller and thinner than the case without this configuration and can be manufactured at a lower cost.

  The mounting component of the present invention is a silicon mounting component that is bonded to a mounting substrate on which a laser element is mounted and optically couples the laser element to an optical fiber, and is predetermined with respect to the bonding surface with the mounting substrate. A groove portion for fixing the optical fiber so that the core of the optical fiber is positioned at a predetermined depth, and a recess portion that is connected to the groove portion and accommodates the laser element therein, and is perpendicular to the bonding surface. The thickness is set such that the position of the laser element can be detected by an infrared transmission image when the bonding surface is brought into contact with the mounting substrate so as to accommodate the laser element in the recess.

  In the mounting component described above, the stopper layer made of silicon on the insulator is included inside, the groove is formed by removing silicon from the bonding surface to the stopper layer, and the recess is formed from the bonding surface to a depth exceeding the stopper layer. It is preferable to be formed by removing.

  In the mounting component described above, the thickness in the direction perpendicular to the joint surface is preferably 200 μm or more and 1000 μm or less.

  In the mounting component described above, it is preferable that the bonding surface has a metal film for surface activation bonding with a metal micro bump provided on the mounting substrate.

  The optical module of the present invention is an optical module that optically couples light from a laser element to an optical fiber, and is mounted on a mounting substrate, a laser element mounted on the mounting substrate, and a bonding surface of the mounting substrate. A mounting part made of silicon having a groove part for fixing the optical fiber so that the core of the optical fiber is positioned at a predetermined depth, and a recess part connected to the groove part to accommodate the laser element inside, The mounting surface of the mounting component is brought into contact with the mounting substrate so that the thickness of the mounting component in the direction perpendicular to the bonding surface accommodates the laser element in the recess. The thickness is sometimes set such that the position of the laser element can be detected by an infrared transmission image.

  In the above optical module, it is preferable that the laser element is mounted on the mounting substrate by junction-up, and the mounting substrate is a flat substrate in which a groove for accommodating the optical fiber is not formed.

  In the above optical module, it is preferable that an integrated circuit for driving the laser element is built in the mounting substrate.

  The manufacturing method of the present invention is a method for manufacturing an optical module in which light from a laser element is optically coupled to an optical fiber, the process of mounting the laser element on a mounting substrate, and a bonding surface with the mounting substrate. A groove portion for mounting a silicon component having a groove portion for fixing the optical fiber so that the core of the optical fiber is positioned at a predetermined depth and a recess portion that is connected to the groove portion and accommodates the laser element therein The step of fixing the optical fiber to the substrate, the step of bringing the joint surface of the mounting component into contact with the mounting substrate so that the laser element is accommodated in the recess, and detecting the position of the laser element from the infrared transmission image, A step of positioning the mounting board and the mounting component so that the optical output coupled to the fiber is maximized, and a step of bonding the positioned mounting component and the mounting board. And butterflies.

  The positioning step of the manufacturing method described above is performed by adjusting the horizontal position of the optical fiber with respect to the laser element based on the alignment mark provided on the mounting substrate while detecting the position of the laser element from the infrared transmission image. Preferably, the method includes determining a horizontal position and a vertical position of the optical fiber relative to the laser element so that the output of the photodetector is maximized while detecting light coupled from the element to the optical fiber with the photodetector. .

  According to the above-mentioned optical fiber mounting component, it is possible to align the laser element and the optical fiber with higher accuracy while protecting the laser element mounted on the substrate. In addition, the above optical module can be made smaller and thinner than the case without this configuration, and can be manufactured at a lower cost.

1 is a perspective view showing a schematic configuration of an optical module 1. FIG. 4 is a perspective view of a sub-board 50. FIG. It is the top view and sectional drawing of the sub board | substrate 50. FIG. FIG. 6 is a view for explaining joints 15 and 16 between the Si platform 10 and the sub-substrate 50 and the LD element 20. It is a perspective view of sub board | substrate 50 '. 6 is a diagram for explaining an example of a manufacturing process of a sub-board 50. FIG. 6 is a diagram for explaining an example of a manufacturing process of a sub-board 50. FIG. 3 is a flowchart showing an example of a manufacturing process of the optical module 1. 1 is a schematic configuration diagram of an alignment apparatus 100. FIG. It is a figure which shows the example of the alignment mark used for the passive alignment of LD element 20 and the optical fiber 40. FIG. It is a figure which shows another example of the alignment mark used for the passive alignment of LD element 20 and the optical fiber 40. FIG. 2 is a schematic configuration diagram of an alignment mounting device 200. FIG. 2 is a perspective view showing a schematic configuration of an optical module 2. FIG. 2 is a perspective view showing a schematic configuration of an optical module 3. FIG. 2 is a perspective view showing a schematic configuration of an optical module 4. FIG. It is sectional drawing which compares the optical modules 4 and 1. FIG. 2 is a cross-sectional view showing a schematic configuration of an optical module 5. FIG.

  Hereinafter, an optical fiber mounting component, an optical module, and a manufacturing method will be described with reference to the drawings. It should be understood, however, that the present invention is not limited to the drawings or the embodiments described below.

  This mounting component functions as, for example, a silicon (Si) fiber submount substrate (hereinafter simply referred to as “sub-substrate”) and a protective component (cover) for the laser element on the mounting substrate. Since silicon transmits near-infrared rays, the position of the internal laser element can be observed with an infrared camera in a state in which the mounting surface is in contact with the mounting substrate so that the mounting component covers the laser element. Therefore, alignment of the laser element and the optical fiber can be performed through the cover by the transmitted image of near infrared light. This mounting component allows the laser element to be packaged with a higher degree of completeness while the laser element is mounted on the substrate.

  FIG. 1 is a perspective view showing a schematic configuration of the optical module 1. The optical module 1 includes a Si platform 10, an LD element 20, a PD element 25, a driver IC 30, an optical fiber 40, a sub board 50, and the like as main components. The optical module 1 is an integrated laser module in which an LD element 20, a driver IC 30, an optical fiber 40, a sub substrate 50, and the like are mounted on an upper surface of a Si platform 10 that is a silicon substrate.

  The Si platform 10 is an example of a mounting substrate, and has a size of about a dozen mm square, for example. The Si platform 10 is provided with a through-silicon via (TSV) penetrating from the top surface to the bottom surface. With this TSV, the wiring of the LD element 20, the PD element 25, and the like is routed to the wiring layer inside the Si platform 10 or the back surface. The Si platform 10 is mounted on a circuit board (not shown) for supplying electric signals to the LD element 20, the driver IC 30 and the like. An electric signal is supplied from the circuit board to each element such as the LD element 20 and the driver IC 30 through the through electrode.

  The LD element (laser element) 20 is a laser diode that emits red, green, or blue laser light. When applied to eye tracking or depth sensing, the LD element 20 may be a laser diode that emits near-infrared laser light of, for example, 780 nm to 1300 nm. The LD element 20 is mounted on the upper surface of the Si platform 10 by surface activated bonding after the driver IC 30 is mounted by solder mounting or the like. In addition, the LD element 20 is mounted with a junction-down (face-down) so that the active layer is positioned on the Si platform 10 side in order to improve the heat dissipation characteristics and position the surface of the Si platform 10 with high accuracy. Is done. Thereby, the p electrode and the n electrode of the LD element 20 are arranged on the mounting surface side and the surface side opposite to the Si platform 10 respectively.

  The PD element 25 is a photodiode for receiving the backward light of the LD element 20 and monitoring the amount of light. The PD element 25 is provided on the back side of the LD element 20 with respect to the laser beam emission direction of the LD element 20. The PD element 25 is mounted on the Si platform 10 with solder.

  The driver IC 30 is a mechanism that drives the LD element 20, and has at least a mechanism that controls current supply to the LD element 20. The driver IC 30 is preferably mounted with a digital interface, and more preferably includes a core part such as a CPU and a memory as a control unit. The driver IC 30 has a size of, for example, about several mm square, and is mounted on the Si platform 10 with solder.

  The optical fiber 40 is, for example, a single mode fiber (SMF) that guides the laser light emitted from the LD element 20. The optical fiber 40 is fixed to the sub-substrate 50 and is fixed to the Si platform 10 via the sub-substrate 50. A GI (Graded Index) lens may be integrally provided at the end of the optical fiber 40 facing the LD element 20 as a coupling member. Further, instead of providing the optical fiber 40, for example, a flat optical waveguide may be mounted on the Si platform 10, and the laser light from the LD element 20 may be guided in the optical waveguide.

  2A and 2B are perspective views of the sub-board 50. FIG. FIGS. 3A and 3B are a plan view and a sectional view taken along line IIIB-IIIB of the sub-substrate 50, respectively. 2A and 3A show the sub-board 50 with the joint surface with the Si platform 10 in FIG. 1 facing upward.

  The sub-board 50 is an example of a silicon mounting component that is bonded to the Si platform 10 on which the LD element 20 is mounted and optically couples the LD element 20 to the optical fiber 40. The sub-board 50 is a component that fixes the optical fiber 40 and also functions as a cover for packaging optical components such as the LD element 20 and the PD element 25.

  As shown in FIG. 2A, the sub-substrate 50 is provided with a groove 51, a recess 52, and a metal film 53. The groove portion 51 is a groove for fixing the optical fiber 40 so that the core of the optical fiber 40 is positioned at a predetermined depth with respect to the joint surface with the Si platform 10, and the joint surface with the Si platform 10. Formed on top. The recess 52 is a recess for accommodating the LD element 20 and the PD element 25 therein, and is formed so as to be connected to the groove 51. The shape of the recess 52 is not limited to the illustrated square box shape. The metal film 53 is a film made of, for example, Au (gold) for surface activation bonding of the sub-substrate 50 on the Si platform 10, and is formed on the bonding surface with the Si platform 10.

  As shown in FIG. 2B, when the sub-board 50 is mounted on the Si platform 10, the sub-board 50 is arranged with the bonding surface provided with the metal film 53 facing downward.

  FIG. 2B also shows part of electrode pads for connecting the electrodes of the LD element 20, the PD element 25, and the driver IC 30 to each other. The n electrode of the LD element 20 is connected to the LD electrode pad 11A through the wire bond 61, and the p electrode is connected to the LD electrode pad 11B. The n electrode of the PD element 25 is connected to the PD electrode pad 12A through the wire bond 62, and the p electrode is connected to the PD electrode pad 12B. These electrode pads are connected to the connection pad 13 via a through electrode of the Si platform 10 (not shown) and an electrode pad provided on the back surface of the Si platform 10. The connection pad 13 is further connected to the driver IC 30 via the wire bond 63 and the driver electrode pad 14.

  Reference numeral 15 on the upper surface of the Si platform 10 in FIG. 2B is a joint portion with the sub-substrate 50. Further, on the upper surface of the Si platform 10, a groove portion 17 (fiber escape groove) for accommodating the optical fiber 40 is formed at a position overlapping the groove portion 51 of the sub substrate 50 when the sub substrate 50 is bonded. .

  As shown in FIGS. 3A and 3B, the recess 52 has a greater depth from the joint surface with the Si platform 10 than the groove 51, and the sub-substrate 50 has a two-stage recess. ing.

  Regarding the groove 51, when the sub-substrate 50 is bonded to the Si platform 10, the distance from the bonding surface between the Si platform 10 and the sub-substrate 50 to the center of the core of the optical fiber 40 becomes a predetermined size. In addition, the depth is strictly controlled. As will be described later, this depth control is realized by using silicon on insulator (SOI) as a stopper layer when the groove 51 is formed in the sub-substrate 50. Accordingly, a mechanism for aligning the optical fiber 40 in the vertical direction (z direction) is provided on the sub-board 50 itself.

  On the other hand, since the recess 52 is simply a recess for accommodating the LD element 20 and the PD element 25, the depth thereof does not necessarily need to be strictly controlled.

  The thickness of the sub-substrate 50 is large enough to protect the LD element 20 when the bonding surface of the sub-substrate 50 is brought into contact with the Si platform 10 so that the LD element 20 is accommodated in the recess 52. It is necessary not to be too large so that the position of the LD element 20 can be detected by an infrared transmission image. In general, since the thickness of the optical fiber 40 is about 125 μm, it is difficult to make the sub-board 50 thinner. Therefore, the thickness of the sub-board 50 is required to be 200 μm or more at least, and is preferably 300 μm or more considering the strength against the load applied during mounting.

  Further, since silicon has high infrared transmittance, it is possible to observe the inside with a transmission image even if the sub-substrate 50 is about 1 mm thick. However, if the thickness is 1 mm or more, the number of wafers obtained from the ingot when the sub-board 50 is manufactured is reduced, and the manufacturing cost is increased. Further, in an infrared camera composed of a CMOS or a CCD sensor using a general silicon as a detector, the sensitivity rapidly decreases in a wavelength region longer than 850 nm. The thickness of the sub-substrate 50 capable of observing a transmission image using illumination light of 850 nm or less is up to about 850 μm, and at a thickness larger than that, an InGaAs sensor having sensitivity on the longer wavelength side is used. There is a need to use expensive infrared cameras in combination with long wavelength near infrared illumination. Therefore, the thickness of the sub-substrate 50 may be about 200 to 1000 μm, but is preferably about 300 to 800 μm in view of strength and manufacturing cost.

  FIGS. 4A and 4B are diagrams for explaining the joint portions 15 and 16 between the Si platform 10 and the sub-substrate 50 and the LD element 20. FIG. 4A is a longitudinal sectional view showing a part of the optical module 1, and FIG. 4B is a partially enlarged view of the joint portion 15.

  As shown in FIG. 4A, joints 15 and 16 between the LD element 20 and the sub-substrate 50 are formed on the surface of the Si platform 10. The joints 15 and 16 are provided with micro bumps (hereinafter simply referred to as “bumps”) made of a metal material such as gold (Au), which are small protrusions having a size of about several μm, at a predetermined pitch. It has been. In FIG. 4A and FIG. 4B, these bumps (bumps 150) are exaggerated and enlarged.

  Further, as shown in FIG. 4A, metal films 53 and 21 made of, for example, Au (gold) are formed on the lower surfaces of the sub-substrate 50 and the LD element 20, respectively. The bumps of the joint portions 15 and 16 and the metal films 53 and 21 are cleaned by Ar plasma before joining. Thereby, each surface is activated. At the time of bonding, the sub-substrate 50 and the LD element 20 are placed on the bonding portions 15 and 16 of the Si platform 10, respectively, and a load is applied at room temperature. Then, the upper surfaces of the bumps of the joints 15 and 16 and the metal films 53 and 21 come into contact with each other, and the bumps are crushed, so that the metal atoms of the bumps and the metal atoms of the metal films 53 and 21 diffuse to each other. Thereby, the sub-substrate 50 and the LD element 20 are surface-activated bonded on the bonding portions 15 and 16 of the Si platform 10 by utilizing the adhesion force between atoms, respectively.

  Since surface activated bonding does not require any special heating, the positional displacement of each element due to residual stress due to the difference in thermal expansion coefficient is unlikely to occur, and it is possible to position and mount a bonded object such as the sub-board 50 with high accuracy. it can. In the optical module 1, the depth of the groove 51 of the sub-board 50 is controlled as described above, and the magnitude of the load applied when the sub-board 50 is bonded is further controlled. It is possible to align the position of the lens more precisely.

  FIG. 5 is a perspective view of the sub-board 50 '. In the optical module 1, the PD element 25 is mounted on the Si platform 10. However, as shown in FIG. 5, the PD element 25 may be mounted on the surface of the recess 52 of the sub-board 50 '. In this case, the surface activated bonding metal film 53 is also used as a conduction pattern of the PD element 25.

  FIGS. 6A to 7D are diagrams for explaining an example of the manufacturing process of the sub-substrate 50. In each of these drawings, similarly to FIGS. 3A and 3B, a plan view and a longitudinal sectional view of the sub-board 50 at each stage of the manufacturing process are shown.

As shown in FIG. 6A, first, a silicon substrate 70 including an SOI stopper layer 54 made of silicon-on-insulator (SOI) is prepared, and the metal film 53 is patterned on the surface thereof. I do. Then, the silicon substrate 70 is heated in an oxidizing atmosphere to form a SiO ₂ (silicon dioxide) film 71 on the upper surface of the silicon substrate 70 as shown in FIG. 6B. Further, as shown in FIG. 6C, a resist 72 is formed on the upper surface of the silicon substrate 70 other than the portion that becomes the groove 51. Next, as shown in FIG. 6D, the SiO ₂ film 71 in the groove 51 where the resist 72 is not formed is removed by wet etching or dry etching.

Subsequently, as shown in FIG. 7A, a resist 73 is formed on the upper surface of the silicon substrate 70 other than the portion that becomes the recess 52. Next, the SiO ₂ film 71 in the recess 52 is removed by wet etching or dry etching, and the silicon in the recess 52 is scraped over the SOI stopper layer 54 as shown in FIG. 7B by D-RIE processing. . When the resist 73 is removed, the SiO ₂ film 71 is exposed at portions other than the recess 52 and the groove 51. Further, by D-RIE processing, as shown in FIG. 7C, the groove 51 is cut down to the SOI stopper layer 54. At this time, the unmasked recess 52 is also shaved by D-RIE processing. Finally, as shown in FIG. 7D, the SOI stopper layer 54 in the groove 51 and the SiO ₂ film 71 in other portions are removed by wet etching or dry etching.

  Through the above steps, the sub-board 50 is obtained. In the groove portion 51 of the completed sub-substrate 50, silicon from the bonding surface with the Si platform 10 to the SOI stopper layer 54 is removed, and in the concave portion 52, silicon from the bonding surface to a depth exceeding the SOI stopper layer 54 is removed. Has been removed.

  FIG. 8 is a flowchart showing an example of the manufacturing process of the optical module 1.

  First, the driver IC 30 and the PD element 25 are mounted on the Si platform 10 with solder (S1). Thereafter, the LD element 20 is surface-activated bonded to the upper surface of the Si platform 10 face-down by passive alignment (S2). In that case, for example, the position of the LD element 20 with respect to the Si platform 10 is determined by aligning the positions of alignment marks (not shown) provided on the Si platform 10 and the LD element 20. In this manner, the LD element 20 is mounted so as not to affect the LD element 20 by soldering first and then performing surface activation bonding.

  Next, for example, a single mode fiber (SMF) having a GI lens that increases the coupling efficiency at the end is fixed to the groove 51 of the sub-substrate 50 as the optical fiber 40 (S3). Then, the bonding surface is brought into contact with the Si platform 10 so that the LD element 20 on the Si platform 10 is accommodated in the recess 52, and the sub-substrate 50 is disposed on the Si platform 10 (S4).

  Next, passive alignment of the LD element 20 and the optical fiber 40 is performed (S5). The passive alignment of S5 is performed using the alignment apparatus 100 shown in FIG.

  FIG. 9 is a schematic configuration diagram of the alignment apparatus 100. The alignment apparatus 100 includes a control unit 101, an infrared camera 102, and a moving mechanism 103. The control unit 101 is configured by a PC including a CPU, a memory, and the like, for example. The infrared camera 102 images the sub-board 50 in which the LD element 20 is accommodated in the recess 52, and outputs the obtained infrared image data to the control unit 101. The moving mechanism 103 moves the sub-substrate 50 disposed on the Si platform 10 in the horizontal plane and in the vertical direction under the control of the control unit 101.

  During the passive alignment, the control unit 101 acquires an infrared image of the sub-board 50 by the infrared camera 102 without causing the LD element 20 to emit light. Then, the control unit 101 detects the position of the LD element 20 and the positions of the alignment marks provided in advance on the Si platform 10 and the sub-substrate 50 from the infrared transmission image, and determines the necessary amount of movement of the sub-substrate 50. To do. The control unit 101 controls the moving mechanism 103 according to the determined moving amount, thereby aligning the positions of the alignment marks provided in advance on the Si platform 10 and the sub-substrate 50.

  FIGS. 10A to 10C are diagrams showing examples of alignment marks used for passive alignment between the LD element 20 and the optical fiber 40. FIG. 10A and 10B are plan views of the Si platform 10 and the sub-substrate 50, respectively. FIG. 10B shows the sub-substrate 50 viewed from the opposite side of the bonding surface with the Si platform 10 (from above). FIG. 10C is a diagram showing a state where the sub-substrate 50 in FIG. 10B is placed on the Si platform 10 in FIG.

  For example, two alignment marks are provided on the diagonal of the Si platform 10 and the sub-substrate 50, respectively. As shown in FIGS. 10A and 10B, two Si platform side marks 81 are provided on the upper surface of the Si platform 10, and two sub substrate side marks 82 are provided on the lower surface of the sub substrate 50. The sub-substrate side mark 82 is provided on the joint surface with the Si platform 10. Note that the shape of the alignment mark is not limited to the illustrated round shape, and may be, for example, a square shape. At the time of passive alignment, the alignment apparatus 100 is configured so that the two Si platform side marks 81 and the sub-substrate side mark 82 overlap each other as shown in FIG. 10C based on the infrared transmission image obtained by the infrared camera 102. Thus, the relative positions of the Si platform 10 and the sub-substrate 50 are determined.

  FIG. 11A to FIG. 11C are diagrams showing another example of alignment marks used for passive alignment of the LD element 20 and the optical fiber 40. These drawings are plan views corresponding to FIGS. 10A to 10C, respectively. As shown in FIGS. 11A to 11C, alignment marks used for passive alignment may be provided on the LD element 20 and the sub-substrate 50 instead of the Si platform 10 and the sub-substrate 50.

  Also in this case, for example, two alignment marks are provided on the diagonal of the LD element 20 and the sub-substrate 50, respectively. As shown in FIGS. 11A and 11B, two LD-side marks 83 are provided on the upper surface of the LD element 20, and two sub-substrate-side marks 84 are provided on the bottom surface of the recess 52 of the sub-substrate 50. It is done. At the time of passive alignment, based on the infrared transmission image by the infrared camera 102, as shown in FIG. 11C, the alignment device 100 makes the two LD side marks 83 and the sub board side mark 84 overlap each other. The relative positions of the Si platform 10 and the sub-substrate 50 are determined.

  By the passive alignment as described above, the rough relative position between the Si platform 10 and the sub-substrate 50 in the horizontal direction (x, y direction) on the bonding surface is roughly adjusted on the order of microns. At this time, the relative position between the optical fiber 40 fixed to the groove 51 of the sub-substrate 50 and the LD element 20 on the Si platform 10 is adjusted with an accuracy of several μm.

  Next, active alignment of the LD element 20 and the optical fiber 40 is performed in the horizontal direction (x, y direction) (S6). The active alignment of S6 and S7 described later is performed using the alignment mounting apparatus 200 shown in FIG.

  FIG. 12 is a schematic configuration diagram of the alignment mounting device 200. The alignment mounting apparatus 200 includes a control unit 201, a photodetector 202, and an alignment mounter 203. The control unit 201 is configured by a PC including a CPU, a memory, and the like, for example. The photodetector 202 detects the intensity of the laser beam coupled to the optical fiber 40 and outputs a detection output voltage corresponding to the intensity to the control unit 201. The aligning mounter 203 joins the mounted component onto the Si platform 10 by applying a load to the mounted component under the control of the control unit 201.

  At the time of active alignment, first, the LD element 20 is driven by the driver IC 30 to emit laser light. At the same time, the control unit 201 monitors the output voltage corresponding to the intensity of the laser beam coupled from the LD element 20 to the optical fiber 40 using the photodetector 202. Then, the control unit 201 finely adjusts the position of the sub-board 50 in the horizontal direction by a sub-micron order using a moving mechanism (not shown), and the position of the sub-board 50 when the output voltage of the photodetector 202 becomes maximum. To decide.

  Next, active alignment of the LD element 20 and the optical fiber 40 is performed in the vertical direction (z direction) (S7). At that time, the control unit 201 detects the intensity of the laser beam coupled from the LD element 20 to the optical fiber 40 by the photodetector 202 and controls the alignment mounter 203 while monitoring the output voltage, thereby The load applied to the substrate 50 is controlled. The bumps provided in the joint 15 are deformed (collapsed) and contracted when a load is applied, but when the load is released, a force to return to the original state is acted by elastic repulsion and returns by the amount of elastic return. It has the characteristic. Therefore, in the active alignment in the vertical direction, the control unit 201 increases the load applied to the sub-substrate 50 and further increases it by a certain amount after the output voltage from the photodetector 202 reaches the maximum value. The alignment mounter 203 is controlled so as to release the load from the center. The sub-substrate 50 is surface-activated bonded and fixed on the Si platform 10 by the load applied by the aligning mounter 203.

  As a result, the end position of the optical fiber 40 becomes a position where it is pushed deeper in the vertical direction by a certain amount than the light emission center of the LD element 20 when a load is applied, and the LD element when the load is released. It returns to the position where it is most efficiently optically coupled with the 20 emission centers. Note that the increase in load described above depends on the alignment mounter 203, the shape of the sub-board 50 to which the load is applied, the material and shape of the bumps of the joint portion 15, and can be calculated experimentally. .

  Finally, the entire Si platform 10 is sealed with resin or glass (S8). The optical module 1 is obtained through the above steps.

  As described above, the optical module 1 uses the silicon sub-substrate 50 having the groove 51 for fixing the optical fiber 40 and the recess 52 for accommodating the LD element 20 therein. And the optical fiber 40 is fixed. Since the thickness of the sub-board 50 is such that the position of the LD element 20 accommodated in the recess 52 can be detected by a transmitted image of near-infrared light, the optical module 1 allows the LD to pass through the cover of the sub-board 50. The element 20 and the optical fiber 40 can be aligned. Therefore, in the optical module 1, the LD element 20 and the optical fiber 40 can be aligned with higher accuracy while protecting the LD element 20 mounted on the substrate.

  The sub-substrate 50 may be used for heat dissipation of the LD element 20, or a hole may be formed in the sub-substrate 50, and the PD element 25 may be bonded thereon. In addition, a structure in which the PD element 25 is integrated on the Si platform 10 and light is confined in the space of the sub-substrate 50 to monitor the light can be considered.

  FIG. 13 is a perspective view illustrating a schematic configuration of the optical module 2. The optical module 2 includes, as main components, an Si platform 10 (an example of a mounting board), LD elements 20R, 20G, and 20B, PD elements 25R, 25G, and 25B, a driver IC 30, optical fibers 40R, 40G, and 40B, and a sub board. 50R, 50G, 50B, etc. The optical module 1 is a laser light source that emits monochromatic laser light, whereas the optical module 2 is a laser light source that emits red (R), green (G), and blue (B) laser light.

  The LD elements 20R, 20G, and 20B are laser diodes that emit red, green, and blue laser beams, respectively. The PD elements 25R, 25G, and 25B are photodiodes for receiving the backward light of the corresponding LD elements 20R, 20G, and 20B and monitoring the light quantity. The optical fibers 40R, 40G, and 40B are, for example, single-mode fibers (SMF) that guide laser beams emitted from the corresponding LD elements 20R, 20G, and 20B.

  Each of the sub-boards 50R, 50G, and 50B is a fiber sub-mount board similar to that described with reference to FIGS. 2A to 3B, and is an example of a mounting component. The sub-substrates 50R, 50G, and 50B fix the corresponding optical fibers 40R, 40G, and 40B, and the LD element 20R and the PD element 25R, the LD element 20G and the PD element 25G, and the LD element 20B and the PD element 25B in the recesses, respectively. It arrange | positions on the Si platform 10 so that it may accommodate.

  Except for the above, the configuration of the optical module 2 is the same as the configuration of the optical module 1. In this way, a plurality of LD elements corresponding to RGB colors are provided on one mounting substrate, and a plurality of optical fibers that respectively guide laser beams from the respective elements are provided with a plurality of sub-modules similar to the optical module 1. It may be fixed by a substrate and at the same time, each LD element may be protected.

  In the optical module 2, one set of RGB elements, PD elements and optical fibers corresponding to RGB are provided on the Si platform. However, a plurality of sets of LD elements, PD elements and PD elements corresponding to RGB are provided on one Si platform. An optical fiber may be provided. Also in this case, similarly to the optical module 2, each set of the LD element, the PD element, and the optical fiber may be fixed or protected by the same sub board as that of the optical module 1.

  FIG. 14 is a perspective view showing a schematic configuration of the optical module 3. The optical module 3 includes a Si platform 10 (an example of a mounting board), an LD array 20A, a PD element 25, a driver IC 30, an optical fiber array 40A, a sub board 50A, and the like as main components. The optical module 1 optically couples laser light from one LD element to one optical fiber, while the optical module 3 optically couples laser light from the LD array to a plurality of optical fibers.

  The sub-substrate 50A is a fiber sub-mount substrate similar to that described with reference to FIGS. 2A to 3B, and is an example of a mounted component. However, unlike the sub-board 50 of the optical module 1, the sub-board 50A has a plurality of grooves corresponding to the number of optical fibers included in the optical fiber array 40A. The sub-substrate 50A is arranged on the Si platform 10 so as to fix each optical fiber of the optical fiber array 40A and accommodate the LD array 20A and the PD element 25 in the recess.

  Except for the above, the configuration of the optical module 3 is the same as the configuration of the optical module 1. As described above, a plurality of LD elements (LD arrays) are provided on one mounting substrate, and a plurality of optical fibers that respectively guide laser beams from the respective LD elements are fixed by one sub-substrate. Each LD element may be protected.

  FIGS. 15A and 15B are perspective views showing a schematic configuration of the optical module 4. FIG. 15A is a perspective view of the completed optical module 4, and FIG. 15B is an exploded perspective view of the optical module 4. FIGS. 16A and 16B are cross-sectional views comparing the optical modules 4 and 1. 16A shows a cross section of the optical module 4 along the XVIA-XVIA line shown in FIG. 15A, and FIG. 16B shows a cross section of the optical module 1 corresponding to FIG. Show.

  The optical module 4 includes a Si platform 10D, an LD element 20 ', a driver IC 30', an optical fiber 40, a sub board 50D, and the like as main components. The optical module 4 is different from the optical modules 1 to 3 in that the LD element 20 ′ is mounted junction-up.

  The Si platform 10D is an example of a mounting substrate. Similar to the Si platform 10 of the optical module 1, the joint portions 15 ′ and 16 ′ and the LD device 20 for surface activation joining the LD element 20 ′ and the sub-substrate 50D. An electrode structure (not shown) for connecting “and the driver IC 30” is provided. However, the Si platform 10D is a flat substrate, and corresponds to the groove portion 17 (fiber escape groove) in the Si platform 10 of the optical module 1, as indicated by reference numeral 18 in FIGS. 15A and 15B. Is not formed.

  In the optical module 4, as shown in FIG. 16A, a driver IC 30 'that is an integrated circuit that drives the LD element 20' is built in the Si platform 10D.

  The LD element 20 ′ is a laser diode similar to the LD element 20 of the optical module 1. However, as shown in FIGS. 16A and 16B, in the optical module 1, the LD element 20 is mounted in a junction-down manner with the active layer 22 facing the Si platform 10, while the optical module 1 4, the LD element 20 ′ is mounted by junction-up with the active layer 22 facing away from the Si platform 10 </ b> D. A symbol L in FIGS. 16A and 16B indicates laser light emitted from the LD elements 20 and 20 ′.

  The sub-board 50D is an example of a mounting component, and has a groove 51 ', a recess 52', and a metal film 53 'similar to those of the sub-board 50 of the optical module 1, as shown in FIG. The thickness of the sub-substrate 50D is set such that the position of the LD element 20 'can be detected by an infrared transmission image in a state where the LD element 20' is accommodated in the recess 52 '. The groove 51 ′ is a groove for fixing the optical fiber 40, and the optical fiber 40 is completely embedded in the sub-board 50D at the fixing portion in response to the LD element 20 ′ being junction-down mounted. And deeper than the groove 51 of the sub-substrate 50. The recess 52 'is a recess for accommodating the LD element 20' therein. The metal film 53 ′ is a joint for surface activation joining with the Si platform 10D, and is substantially around the groove 51 ′ and the recess 52 ′ at a position corresponding to the joint 15 ′ of the Si platform 10D. It is formed in a letter shape. Thus, the joint for surface activated joining does not need to be formed on the entire surface of the sub-substrate.

  Usually, the LD element is mounted by junction-down with the active layer serving as a light emitting point on the mounting surface side (lower side) in order to improve heat dissipation. Junction down mounting also has an advantage that the light emitting point of the LD element is close to the mounting surface of the mounting substrate, which is the reference surface, and is easily aligned with the reference surface. However, since the active layer of the LD element mounted with junction down is approximately the same height as the mounting surface, in order to align the optical fiber with respect to the LD element, the optical fiber should not be in contact with the mounting surface. It is necessary to provide an optical fiber relief groove on the mounting substrate. For example, in the optical module 1, as shown in FIG. 16B, not only the sub-substrate 50 is provided with the groove 51 for fixing the optical fiber 40, but also the Si platform 10 becomes a relief groove for the optical fiber 40. A groove portion 17 is provided. Accordingly, it is necessary to provide grooves by machining on both the LD element mounting substrate and the mounting component bonded thereto, and the number of manufacturing steps is increased correspondingly, and the two grooves provide the sealing of the LD element. The sex will be reduced.

  On the other hand, when an optical module is used for, for example, a retinal scanning type scan, the LD light source may have a low power of about several hundreds nW to several mW, so that junction down mounting considering heat dissipation is not necessary. For this reason, it becomes possible to join the LD element to the mounting substrate by junction-up mounting with the light emitting portion facing away from the mounting surface. Therefore, in the optical module 4, the LD element 20 'is mounted junction-up on the Si platform 10D.

  For example, the thickness of the LD element 20 ′ is about 100 μm, whereas the diameter of the optical fiber 40 is about 80 to 125 μm and the radius is about 40 to 62.5 μm. For this reason, in the optical module 4, as shown in FIG. 16A, the position of the active layer 22 is higher than the upper surface of the Si platform 10D by the thickness of the LD element 20 ′. The position 40 is also the height embedded in the sub-board 50D. Therefore, in the optical module 4, since the lower end of the optical fiber 40 arranged in accordance with the height of the light emitting point of the LD element 20 ′ does not contact the upper surface of the Si platform 10D, the escape groove of the optical fiber 40 is formed in the Si platform 10D. There is no need to form.

  Thereby, in the optical module 4, it is possible to make the Si platform 10D a flat substrate without a groove, and the manufacturing process for machining the Si platform 10D is simplified. Further, in the optical module 4, the driver IC 30 ′ (integrated circuit) is incorporated in the Si platform 10 D, and the height of the optical fiber 40 is adjusted by the sub-substrate 50 D having the groove 51 ′ and the recess 52 ′. It is possible to separate the functions with the substrate. In the optical module 1, since the Si platform 10 also has the groove portion 17, the effective area is reduced to incorporate the integrated circuit. However, in the optical module 4, the integrated circuit and the wiring are densely arranged in the flat Si platform 10D. It is possible to form. Further, the optical module 4 has an advantage that the sealing performance of the LD element 20 ′ is improved because the Si platform 10 D has no groove.

  Since the LD element is mechanically polished on the opposite side of the active layer at the time of manufacture, there is an error in the overall thickness, and in the case of junction-up mounting, the error can greatly affect. Therefore, in the optical module 4, the thickness of the LD element 20 ′ to be used is measured in advance, and the depth of the groove 51 ′ is set so that the position of the optical fiber 40 can be aligned with the light emitting point of the LD element 20 ′. Then, the sub-board 50D having the groove 51 'having the depth is manufactured and used. Thereby, it becomes possible to eliminate the influence of the error of the thickness of the LD element due to the junction-up mounting.

  FIG. 17 is a cross-sectional view showing a schematic configuration of the optical module 5. The optical module 5 includes a Si platform 10E, an LD element 20 ', a driver IC 30', an optical fiber 40, a sub board 50E, and the like as main components. The optical module 5 is different from the optical modules 1 to 4 in that the LD element 20 'is mounted on the flat sub-board 50E.

  The Si platform 10E is an example of a mounting component, and includes a recess 19A that houses the LD element 20 'and a groove 19B that houses the optical fiber 40. The groove portion 19B is formed at a depth at which the optical fiber 40 is completely embedded in the Si platform 10E at the portion fixed by the Si platform 10E. The thickness of the Si platform 10E is set such that the position of the LD element 20 'can be detected by an infrared transmission image in a state where the LD element 20' is accommodated in the recess 19A.

  The LD element 20 'is the same laser diode as that of the optical module 4, and is mounted on the sub-board 50E with the active layer 22 facing away from the sub-board 50E. Reference symbol L in FIG. 17 indicates laser light emitted from the LD element 20 '.

  The sub-board 50E is an example of a mounting board, and is a flat board that is not provided with a recess or the like unlike the sub-board described so far. In the optical module 5, as shown in FIG. 17, a driver IC 30 ', which is an integrated circuit for driving the LD element 20', is built in the sub-board 50E. Note that the Si platform 10E and the sub-substrate 50E have a joint (not shown) for surface activation joining to each other.

  In the optical module 5, the concave portion 19A for accommodating the LD element 20 ′ is provided in the Si platform 10E, and the sub-board 50E is made flat, so that integrated circuits and wirings can be formed on the sub-board 50E at a high density. It becomes possible. For this reason, in the optical module 5, it becomes easy to incorporate the driver IC 30 'in the sub-board. For example, it is possible to make a pass / fail judgment on the LD element 20' by using the sub-board alone. For the sub-substrate 50 ', an integrated circuit is formed at the stage on the wafer and a large number of LD elements are mounted, so that aging (energization test) of these elements is performed in a lump, and non-defective and defective elements are detected. It is possible to sort. For this reason, if the wafer is divided and used as the sub-substrate 50 ', the optical module can be manufactured in a state where only non-defective products are selected from the beginning, and the man-hour can be greatly reduced. Further, since only the Si platform 10E is formed with the recesses and the grooves, it is only necessary to machine one substrate, and this also simplifies the manufacturing process.

  In the above description, it has been described that the p electrode and the n electrode of the LD element 20 are arranged on the mounting surface side with respect to the Si platform 10 and the opposite side thereof. However, as the LD elements 20 and 20 ′, the p electrode and the n electrode are provided. Both may be provided on the mounting surface side. In this case, a wire bond (wire bond 61 in FIG. 2B) is not required to connect the LD elements 20 and 20 ′, and accordingly, the depth of the concave portion that accommodates the LD elements 20 and 20 ′ is reduced accordingly. Can do. Therefore, it is possible to further reduce the thickness of the sub-board and further the entire optical module.

1, 2, 3, 4, 5 Optical module 10, 10D, 10E Si platform 15, 15 ′, 16, 16 ′ Junction 17 Groove 20, 20 ′, 20R, 20G, 20B, 20A LD element 22 Active layer 25, 25R, 25G, 25B PD element 30, 30 'driver IC
40, 40R, 40G, 40B, 40A Optical fiber 50, 50 ', 50R, 50G, 50B, 50A, 50D, 50E Sub-board 51, 51' Groove 52, 52 'Recess 53, 53' Metal film

Claims (9)

A mounting component made of silicon that is bonded to a mounting substrate on which a laser element is mounted and optically couples the laser element to an optical fiber,
A groove portion for fixing the optical fiber so that the core of the optical fiber is located at a predetermined depth with respect to the joint surface with the mounting substrate;
A recess connected to the groove and accommodating the laser element therein,
The thickness in the direction perpendicular to the bonding surface can detect the position of the laser element by an infrared transmission image when the bonding surface is brought into contact with the mounting substrate so that the laser element is accommodated in the recess. Set to thickness,
Mounting parts characterized by that. Contains a stopper layer with silicon on insulator inside,
The groove is formed by removing silicon from the bonding surface to the stopper layer,
The mounting part according to claim 1, wherein the recess is formed by removing silicon from the joint surface to a depth exceeding the stopper layer.   The mounting component according to claim 1, wherein a thickness in a direction perpendicular to the joint surface is 200 μm or more and 1000 μm or less.   The said joining surface is a mounting component as described in any one of Claims 1-3 which has a metal film for surface activation joining between metal micro bumps provided on the mounting board | substrate. An optical module for optically coupling light from a laser element to an optical fiber,
A mounting board;
A laser element mounted on the mounting substrate;
A groove portion for fixing the optical fiber so that the core of the optical fiber is located at a predetermined depth with respect to the joint surface with the mounting substrate, and the laser element is accommodated in the groove portion and connected to the groove portion. Mounting parts made of silicon having a recess for,
An optical fiber fixed in the groove of the mounting component,
The thickness of the mounting component in a direction perpendicular to the bonding surface is determined by an infrared transmission image when the bonding surface of the mounting component is brought into contact with the mounting substrate so that the laser element is accommodated in the recess. Set to a thickness that can detect the position of the laser element,
An optical module characterized by that. The laser element is mounted on the mounting substrate at junction up,
The optical module according to claim 5, wherein the mounting substrate is a flat substrate in which a groove for accommodating the optical fiber is not formed.   The optical module according to claim 6, wherein an integrated circuit for driving the laser element is built in the mounting substrate. An optical module manufacturing method for optically coupling light from a laser element to an optical fiber,
Mounting a laser element on a mounting substrate;
A groove portion for fixing the optical fiber so that the core of the optical fiber is located at a predetermined depth with respect to the joint surface with the mounting substrate, and the laser element is accommodated in the groove portion and connected to the groove portion. Fixing the optical fiber in the groove of the silicon mounting component having a recess for
Contacting the joint surface of the mounting component with the mounting substrate so as to accommodate the laser element in the recess;
Positioning the mounting substrate and the mounting component so that the light output coupled from the laser element to the optical fiber is maximized while detecting the position of the laser element by an infrared transmission image;
Joining the positioned mounting component and the mounting substrate;
The manufacturing method characterized by having. The positioning step includes
While detecting the position of the laser element by an infrared transmission image, with reference to an alignment mark provided on the mounting substrate, the horizontal position of the optical fiber relative to the laser element is adjusted,
While the light coupled from the laser element to the optical fiber is detected by a photodetector, the horizontal position and the vertical position of the optical fiber with respect to the laser element are determined so that the output of the photodetector is maximized. ,
The manufacturing method of Claim 8 including this.

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