Optical connection structure and manufacturing method thereof

Abstract

This optical connection structure (10) comprises: a first optical element (11) disposed on a first substrate (111) and having a first waveguide (113); a second optical element (12) having a second waveguide (123); a self-formed waveguide (131) connecting one end of the first waveguide (113) and one end of the second waveguide (123); and a first received light guiding part (114) disposed at the other end of the first optical waveguide (113).　Consequently, the present invention can provide a low-loss optical connection structure using a self-formed waveguide.

Description

[Technical Field]

[0001] The present invention relates to an optical connection structure using a self-written waveguide and a method for manufacturing the same. [Background technology]

[0002] Efforts are being made to improve functionality by connecting heterogeneous substrates using planar lightwave circuits (PLCs) with optical waveguides, silicon photonics (SiPh) circuits, indium phosphide (InP) compound semiconductor chips, and the like (Non-Patent Document 1).

[0003] As with electrical circuits, research is also underway into low-cost batch manufacturing technology at the wafer level, in which optical element chips made on other substrates are joined to other substrates to form fan-out packages (Non-Patent Document 2). In Non-Patent Document 2, light from the optical element chip is emitted into space.

[0004] Using these techniques, for example, as shown in FIG. 14A, PLC chips 51 having glass waveguides 513 are formed periodically on a wafer 5_1, and then recesses 515 are formed to expose the silicon of the substrate.

[0005] Meanwhile, a laser diode (LD) (not shown) is formed on another indium phosphide substrate and diced into chips. The LD chip 52 is mounted and fixed so that the optical waveguide 523, which propagates light from the LD of the LD chip 52, is connected to the glass waveguide 513 of the PLC chip 51 (FIG. 14B).

[0006] This process can be performed using image recognition for alignment and intermolecular forces for fixation, and there are bonding machines specifically designed for this process, which allow for the integrated mounting of chips made of different materials on a wafer in one go. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] Y. Kurata et al., “Heterogeneously Integrated PLC With Low-LossSpot-Size Converter and Newly Developed Waveplate PBS for DC-DP-16QAM Receiver,” Journal of Lightwave Technology, vol. 33, No.6, pp. 1202-1209, 2015. [Non-patent document 2] C. Prevatte et al., “Miniature Heterogeneous Fan-Out Packages for High-Performance, Large-Format Systems,” Electronic Components and Technology Conference, pp. 1098-1106. Summary of the Invention [Problem to be solved by the invention]

[0008] However, since visible light is used for image recognition, it has been difficult to position and mount the device with a positional accuracy sufficiently high compared to the wavelength of visible light.

[0009] Furthermore, it was difficult to ensure the positional repeatability of the mechanical chip handling tool, and the positional accuracy was limited to about ±3 microns. This accuracy is not a problem when emitting light into space or ensuring electrical connections, but it is insufficient when connecting waveguides together.

[0010] For example, in a PLC using glass materials, the width of the optical waveguide is about 10 microns, so if the positions of the optical waveguides to be connected are misaligned by 3 microns, the optical connection loss increases.

[0011] Furthermore, when the refractive index of the waveguide material is high, such as in SiN waveguides, InP waveguides, and SiPh waveguides, the width of the optical waveguide becomes narrow, and there is a problem that optical connection cannot be made with an accuracy of ±3 microns because of the large loss. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems, a manufacturing method of an optical connection structure according to the present invention is a manufacturing method of an optical connection structure for optically connecting a first optical element having a first optical waveguide and a first light-receiving light-guiding portion arranged at the other end of the first optical waveguide, and a second optical element having a second optical waveguide and a second light-receiving light-guiding portion arranged at the other end of the second optical waveguide, the manufacturing method of an optical connection structure comprising the steps of: forming a plurality of the first optical elements collectively at predetermined intervals on a first wafer substrate; forming a plurality of recesses on the first wafer substrate in contact with each of the plurality of first optical elements; forming a plurality of the second optical elements collectively on a second substrate to form chips of the second optical elements; arranging each of the plurality of second optical elements in the plurality of recesses so that an end face of the first optical waveguide and an end face of the second optical waveguide are close to each other, and fixing the first optical element and the second optical element; and filling a photocurable resin between the end face of the first optical waveguide and the end face of the second optical waveguide. Work Resin curing process and light of The first light-receiving light-guiding portions of the first optical elements and the first light-receiving light-guiding portions of the first optical elements are exposed through openings in an exposure mask. 2 and the light is incident on the second light receiving guide portion of the optical element in a direction perpendicular to the first wafer substrate. Let The waveguide direction of the resin curing light is changed to the horizontal direction of the first wafer substrate, and the resin curing light is incident on the first optical waveguide. Let , the first optical waveguide to Waveguide Let , the photocurable resin is irradiated By doing sothe step of forming a plurality of self-forming waveguides at once, the self-forming waveguides connecting the first optical waveguides of the plurality of first optical elements to the second optical waveguides of the plurality of second optical elements, respectively; and the step of forming a cladding around the self-forming waveguides, the cladding having a refractive index lower than that of the self-forming waveguides, wherein the openings of the exposure mask are periodically arranged at the predetermined intervals. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a low-loss optical connection structure using a self-written waveguide and a method for manufacturing the same. [Brief explanation of the drawings]

[0015] [Figure 1A] FIG. 1A is a schematic top view showing the configuration of an optical connection structure according to a first embodiment of the present invention. [Figure 1B] FIG. 1B is a schematic side view showing the configuration of the optical connection structure according to the first embodiment of the present invention. [Figure 1C] FIG. 1C is a schematic top view showing the configuration of a second optical element in the optical connection structure according to the first embodiment of the present invention. [Figure 2A] FIG. 2A is a schematic top view illustrating an example of a method for manufacturing the optical connection structure according to the first embodiment of the present invention. [Figure 2B] FIG. 2B is a schematic side view for explaining an example of a method for manufacturing the optical connection structure according to the first embodiment of the present invention. [Figure 2C] FIG. 2C is a schematic side view for explaining an example of a method for manufacturing the optical connection structure according to the first embodiment of the present invention. [Figure 2D] FIG. 2D is a schematic side view for explaining an example of a method for manufacturing the optical connection structure according to the first embodiment of the present invention. [Figure 2E] FIG. 2E is a schematic side view for explaining an example of a method for manufacturing the optical connection structure according to the first embodiment of the present invention. [Figure 2F]FIG. 2F is a schematic side view for explaining an example of a method for manufacturing the optical connection structure according to the first embodiment of the present invention. [Figure 2G] FIG. 2G is a schematic side view for explaining an example of a method for manufacturing the optical connection structure according to the first embodiment of the present invention. [Figure 2H] FIG. 2H is a schematic side view for explaining an example of a method for manufacturing the optical connection structure according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a schematic side view for explaining an example of a method for manufacturing the optical connection structure according to the first embodiment of the present invention. [Figure 4A] FIG. 4A is a schematic top view for explaining the effects of the optical connection structure and the manufacturing method thereof according to the first embodiment of the present invention. [Figure 4B] FIG. 4B is a schematic top view for explaining the effects of the optical connection structure and the manufacturing method thereof according to the first embodiment of the present invention. [Figure 5A] FIG. 5A is a schematic top view showing an example of the configuration of a light-receiving light-guiding section in the optical connection structure according to the first embodiment of the present invention. [Figure 5B] FIG. 5B is a schematic side view showing an example of the configuration of the light-receiving light-guiding section in the optical connection structure according to the first embodiment of the present invention. [Figure 6A] FIG. 6A is a schematic top view showing an example of the configuration of a light-receiving light-guiding section in the optical connection structure according to the first embodiment of the present invention. [Figure 6B] FIG. 6B is a schematic side view showing an example of the configuration of the light-receiving light-guiding section in the optical connection structure according to the first embodiment of the present invention. [Figure 7A] FIG. 7A is a schematic top view showing an example of the configuration of a light-receiving light-guiding section in the optical connection structure according to the first embodiment of the present invention. [Figure 7B] FIG. 7B is a schematic side view showing an example of the configuration of the light-receiving light-guiding section in the optical connection structure according to the first embodiment of the present invention. [Figure 8A] FIG. 8A is a schematic top view showing an example of the configuration of a light-receiving light-guiding section in the optical connection structure according to the first embodiment of the present invention. [Figure 8B] FIG. 8B is a schematic side view showing an example of the configuration of the light-receiving light-guiding section in the optical connection structure according to the first embodiment of the present invention. [Figure 9A] FIG. 9A is a schematic top view showing an example of the configuration of a light-receiving light-guiding section in the optical connection structure according to the first embodiment of the present invention. [Figure 9B] FIG. 9B is a schematic side view showing an example of the configuration of the light-receiving light-guiding section in the optical connection structure according to the first embodiment of the present invention. [Figure 10A] FIG. 10A is a schematic top view illustrating an optical connection structure according to a second embodiment of the present invention. [Figure 10B] FIG. 10B is a schematic side view illustrating the configuration of the optical connection structure according to the second embodiment of the present invention. [Figure 10C] FIG. 10C is a schematic top view illustrating the optical connection structure according to the second embodiment of the present invention. [Figure 10D] FIG. 10D is a schematic side view illustrating the configuration of the optical connection structure according to the second embodiment of the present invention. [Figure 11] FIG. 11 is a schematic side view illustrating the configuration of a second element in an optical connection structure according to a second embodiment of the present invention. [Figure 12A] FIG. 12A is a schematic side view illustrating an example of the configuration of an optical connection structure according to the second embodiment of the present invention. [Figure 12B] FIG. 12B is a schematic side view illustrating an example of the configuration of the optical connection structure according to the second embodiment of the present invention. [Figure 13A] FIG. 13A is a schematic top view illustrating an example of a method for manufacturing an optical connection structure according to the third embodiment of the present invention. [Figure 13B] FIG. 13B is a schematic side view for explaining an example of a method for manufacturing the optical connection structure according to the third embodiment of the present invention. [Figure 13C] FIG. 13C is a schematic side view for explaining an example of a method for manufacturing an optical connection structure according to the third embodiment of the present invention. [Figure 13D]FIG. 13D is a schematic top view for explaining an example of a method for manufacturing the optical connection structure according to the third embodiment of the present invention. [Figure 13E] FIG. 13E is a schematic side view for explaining an example of a method for manufacturing an optical connection structure according to the third embodiment of the present invention. [Figure 13F] FIG. 13F is a schematic top view for explaining an example of a method for manufacturing an optical connection structure according to the third embodiment of the present invention. [Figure 13G] FIG. 13G is a schematic side view for explaining an example of a method for manufacturing the optical connection structure according to the third embodiment of the present invention. [Figure 14A] FIG. 14A is a schematic top view illustrating the configuration of a conventional optical connection structure. [Figure 14B] FIG. 14B is a schematic top view for explaining the configuration of a conventional optical connection structure. DETAILED DESCRIPTION OF THE INVENTION

[0016] First Embodiment An optical connection structure according to a first embodiment of the present invention will be described with reference to FIGS. 1A to 9B.

[0017] <Configuration of optical connection structure> As shown in Figures 1A and 1B, the optical connection structure 10 according to this embodiment includes a first substrate 111, a first element 11, a second element 12, and a self-written waveguide 131 (SWW) between the first element 11 and the second element 12.

[0018] In the optical connection structure 10, the first element 11 is a PLC chip, and includes a glass waveguide 113. The glass waveguide 113 functions as a waveguide core, and has a cladding 112 around it.

[0019] One end face (hereinafter referred to as the "glass waveguide end face") 117 of glass waveguide 113 is exposed toward second element 12, and the other end face is connected to first light-receiving / guiding section 114. Hereinafter, the end face of PLC chip 11 having glass waveguide end face 117 will be referred to as the "PLC end face."

[0020] Furthermore, a waveguide branching from the glass waveguide 113 is connected to an optical circuit (not shown). Here, the optical circuit has functions such as multiplexing / demultiplexing and wavelength separation by the glass waveguide 113.

[0021] Hereinafter, in the horizontal plane (substrate surface), the longitudinal direction (X direction in the figure) of the glass waveguide 113 of the PLC chip 11 will be referred to as the "waveguide direction," the direction perpendicular to the longitudinal direction (Y direction in the figure) will be referred to as the "width direction," the direction perpendicular to the horizontal plane (substrate surface) (Z direction) will be referred to as the vertical (thickness) direction, and in the PLC chip 11, the side on which the glass waveguide 113 is arranged will be referred to as the "upper" direction, and the first substrate 111 side will be referred to as the "lower" direction.

[0022] The first light receiving and guiding section 114 has the function of changing the path of part of the light incident on the top surface of the PLC chip 11, passing it through the glass waveguide 113 and emitting it from the glass waveguide end surface 117, and is formed, for example, from a mirror.

[0023] The first substrate 111 on which the PLC chip 11 is formed has a recess 115, and the glass waveguide end face 117 is disposed above a side wall 115_2 of the recess 115.

[0024] The second element 12 is an LD chip, and is formed on the second substrate 121. The bottom surface (rear surface) of the second substrate 121 of the LD chip 12 is brought into contact with the upper surface of the recess 115 and fixed.

[0025] 1C, the LD chip 12 includes an LD active layer 126, an InP waveguide 125, a SiN waveguide 123, and a second light-receiving guide 124. Here, the surface on the InP waveguide 125 side is the front surface of the LD chip 12, and the surface on the second substrate 121 side is the back surface of the LD chip 12.

[0026] An InP waveguide 125 is connected to the LD active layer 126, and the InP waveguide 125 is connected to the SiN waveguide 123. The tip of the InP waveguide 125 has a tapered spot size converter (SSC).

[0027] In this embodiment, the InP waveguide 125 is covered with and connected to the SiN waveguide 123. However, the present invention is not limited to this, and the InP waveguide 125 may be disposed close to the SiN waveguide 123 as long as the InP waveguide 125 is disposed so that the laser light guided through the InP waveguide 125 is optically coupled to the SiN waveguide 123.

[0028] An end face (hereinafter referred to as "SiN waveguide end face") 127 at one end of the SiN waveguide 123 is exposed toward the first element (PLC chip) 11, and the other end is connected to the second light-receiving and guiding section 124. Hereinafter, the end face of the LD chip 12 having the SiN waveguide end face 127 will be referred to as the "LD end face."

[0029] Similarly to first light-receiving light-guiding section 114, second light-receiving light-guiding section 124 converts the optical path of light incident from the upper surface, guides the light into SiN waveguide 123, and emits the light from end surface 127 of the SiN waveguide.

[0030] In the self-written waveguide 131 , one end face is connected to the glass waveguide end face 117 of the first element 11 , and the other end face is connected to the SiN waveguide end face 127 of the second element 12 .

[0031] In the optical connection structure 10 , the laser light emitted from the LD active layer 126 is guided in order through the InP waveguide 125 and the SiN waveguide 123 , then guided through the self-written waveguide 131 , and then incident on the glass waveguide 113 .

[0032] The reason why the InP waveguide 125 is connected to the SiN waveguide 123 is that the transmittance of visible and ultraviolet light is low in InP but high in SiN, which is necessary for forming a self-written waveguide, which will be described later.

[0033] In the embodiment of the present invention, an example has been shown in which the light-receiving light-guiding section is disposed at the other end of both the first optical waveguide and the second waveguide, but it may be disposed at either one of them.

[0034] <Method of manufacturing optical connection structure> In the manufacturing method of the optical connection structure 10, first, a photocurable resin is filled between the PLC end face of the PLC chip 11 and the LD end face of the LD chip 12, and visible light (resin curing light) is incident on the top surface of the first light-receiving light-guiding section 114 and the second light-receiving light-guiding section 124.

[0035] This visible light (resin curing light) is emitted from glass waveguide end face 117 and SiN waveguide end face 127 on the wafer, and is locally irradiated onto and cured by the photocurable resin, thereby connecting glass waveguide end face 117 and SiN waveguide end face 127 in a self-aligned manner. Unreacted photocurable resin is then removed to form self-forming waveguide 131. Finally, the wafer is diced to form PLC chip 11 on which LD chip 12 is mounted.

[0036] The method for manufacturing the optical connection structure 10 will be described in detail below with reference to FIGS. 2A to 3. FIG.

[0037] First, the PLC chip 11 is formed on the wafer 1_1, and a recess 115 is formed in the substrate (FIGS. 2A and 2B).

[0038] Next, the LD chip 12 made from another wafer is mounted and fixed in the recess 115 (FIGS. 2C and 2D).

[0039] The mounting equipment can be a die bonder, flip chip device, transfer printing device, etc., which can pick up a chip and mount it in the specified location using image recognition. The bonding methods that can be used include bonding by intermolecular forces, adhesion using epoxy resin, ultrasonic bonding of metal bumps to ensure electrical conductivity, and fusion bonding using thin solder film.

[0040] In this process, variations in height occur in the vertical direction of the substrate due to processing errors in the recesses and variations in the substrate thickness of the LD chip 12. Also, positional deviations of about 3 microns occur in the horizontal direction of the wafer.

[0041] Next, a photocurable resin 14 is formed by spin coating, and exposed to light using a mask in an exposure device (FIG. 2E).

[0042] In this embodiment, an exposure device exposes the upper surface of an exposure mask 161 to g-line (wavelength 436 nm) resin curing light 15, and the resin curing light 15 that passes through openings 162 in the exposure mask 161 is incident on the first light-receiving light-guiding section 114 and the second light-receiving light-guiding section 124.

[0043] In exposure mask 161, openings 162 are periodically arranged so as to correspond to the positions of first light-receiving light-guiding section 114 and second light-receiving light-guiding section .

[0044] At this time, for example, a fine linear pattern is formed in the opening 162 to serve as a diffraction grating, so that the resin curing light 15 passing through the exposure mask 161 has a component in a direction other than the vertical.

[0045] Resin curing light 15 is incident on first light-receiving light-guiding section 114 and second light-receiving light-guiding section 124 .

[0046] Resin curing light 15 incident on first light-receiving and guiding section 114 is guided to glass waveguide 113 and exits from end surface 117 of the glass waveguide.

[0047] On the other hand, the resin curing light 15 incident on the second light-receiving light-guiding portion 124 of the LD chip 12 is guided to the SiN waveguide 123 and emitted from the end face 127 of the SiN waveguide.

[0048] As a result, resin curing light 15 is irradiated onto photocurable resin 14 from both glass waveguide 113 and SiN waveguide 123, forming self-forming waveguide 131 and establishing optical connection between glass waveguide 113 and SiN waveguide 123 (FIG. 2F).

[0049] Next, a self-forming waveguide cladding is formed around the self-forming waveguide 131. For example, the self-forming waveguide cladding can be formed by using a resin that generates a difference in refractive index between the portion cured by ultraviolet light and the portion cured by heat as the photocurable resin 14. Here, the refractive index of the portion cured by heat is lower than the refractive index of the portion cured by ultraviolet light.

[0050] More specifically, a chemical reaction caused by exposure progresses, and the photocurable resin 14 hardens to form the self-forming waveguide 131. On the other hand, if the unreacted portion of the photocurable resin 14 is liquid, the entire resin including the liquid unreacted portion is thermally hardened.

[0051] As a result, a difference in refractive index occurs between the part that is cured by ultraviolet light and the part that is cured by heat, so the refractive index of the unreacted part of the photocurable resin 14 that is cured by heat (the part surrounding the self-forming waveguide 131) becomes lower than the refractive index of the self-forming waveguide 131, and forms a cladding.

[0052] Alternatively, after removing the unreacted portion of the photocurable resin 14, a self-written waveguide clad may be formed around the self-written waveguide 131.

[0053] Specifically, the unreacted photocurable resin 14 is removed by a developer device using a developer (FIG. 2G).

[0054] Next, a material having a refractive index lower than that of the self-written waveguide 131 can be spin-coated and cured to form the cladding 132 of the self-written waveguide 131 (FIG. 2H).

[0055] Furthermore, after this step, electrical connections can be made from above by a rewiring step or wire bonding.

[0056] In this manner, the optical connection structure 10 is formed on the wafer. Finally, the wafer on which the optical connection structure 10 has been formed (see FIG. 4A, which will be described later) is diced.

[0057] Furthermore, in the process of mask exposure using the above-mentioned exposure device, as shown in FIG. 3, by placing a lens 163 on the exposure mask 161 instead of using the opening 162 as a diffraction grating, the irradiated light (resin curing light 15) from the exposure machine can be focused and enlarged.

[0058] Fig. 4A shows a wafer 1_2 on which the optical connecting structure 10 is manufactured by the above-mentioned method, and Fig. 4B shows an enlarged view of a part of the wafer 1_2 (enclosed by the dotted line in Fig. 4A).

[0059] In the optical connection structure 10, even if the LD chip 12 is mounted at an angle (tilted) toward the waveguide direction in the horizontal plane, in other words, even if the mounting position contains an error, the glass waveguide 113 of the PLC chip 11 and the SiN waveguide 123 of the LD chip 12 are connected by the self-formed waveguide 131.

[0060] In this way, the self-written waveguide 131 is formed so as to correct the positional deviation, so that the mounting error (about ±3 microns) of the LD chip 12 is absorbed, and the LD chip 12 and the PLC chip 11 can be connected with low loss.

[0061] In this embodiment, the self-written waveguide 131 can be manufactured in bulk using processes and equipment similar to those used in wafer processes for ordinary electrical circuits, and therefore, there is no need to develop special equipment, which is advantageous for integrated packaging of electrical chips and chips made of different optical materials.

[0062] Although this embodiment has a glass waveguide 113 and a SiN waveguide 123, other combinations of materials may be used as long as they transmit light of the wavelength that cures the photocurable resin 14. Furthermore, Si and InP have high transmittance for infrared light used in communications but low transmittance for visible light used for curing, so in such cases, a waveguide made of Si or InP can be connected to a waveguide made of glass, SiN, or SiOx to enable use in communications.

[0063] <Modification> An optical connection structure according to a modified example of the first embodiment of the present invention will be described with reference to Figures 5A to 9B. This modified example differs from the first embodiment in the configuration of the light-receiving light-guiding section in the optical connection structure.

[0064] 5A to 9B, the optical connection structure according to this modification includes a first light-receiving and guiding section 114 at an end of a glass waveguide 113. One end of another glass waveguide 116 is connected to the glass waveguide 113, and the other end of the other glass waveguide 116 is connected to an optical circuit (not shown).

[0065] The refractive index of the other glass waveguide 116 may be equal to or different from the refractive index of the glass waveguide 113. If the refractive index of the other glass waveguide 116 is higher than the refractive index of the glass waveguide 113, the tip of the other glass waveguide 116 may have a tapered spot size converter (SSC). Furthermore, the other glass waveguide 116 may be covered by and connected to the glass waveguide 113, or the two may be arranged close to each other, as long as the glass waveguides 113 and 116 are arranged so as to be optically coupled to each other.

[0066] In this modification, the first light receiving and guiding section 114 in the PLC chip 11 is taken as an example, but it may also be applied to the second light receiving and guiding section 124 of the LD 12 chip.

[0067] 5A and 5B, first light-receiving and guiding unit 114 may use diffraction grating 21. A metal film pattern is formed as diffraction grating 21. Resin curing light 15 incident from above first light-receiving and guiding unit 114 is interfered with (reflected by) by diffraction grating 21, and a portion of resin curing light 15 is guided into glass waveguide 113.

[0068] 6A and 6B, a mirror 22 may be used in first light-receiving light-guiding section 114. Here, mirror 22 is formed in a part of first light-receiving light-guiding section 114. As a result, a part of resin curing light 15 reflected by mirror 22 is guided into glass waveguide 113.

[0069] The mirror 22 is configured by tilting the other end face of the PLC chip, including the other end face of the glass waveguide 113, toward the substrate 111.

[0070] 7A and 7B, a configuration using a lens structure 231 may also be used. In this configuration, a condenser mirror is formed on the substrate 111 as the lens structure 231.

[0071] First, the recess 233 is formed in the substrate 111 by etching.

[0072] Next, resin is placed on the corners of the bottom surface of the recess 233, and the surface of the resin is curved due to the surface tension of the resin.

[0073] Finally, a thin metal film is vapor-deposited onto the curved resin surface.

[0074] This forms a collecting mirror (lens structure) 231 made of resin. This collecting mirror 231 collects a portion of the resin curing light 15 that has entered the recess 233 toward the glass waveguide 113, and causes the light to enter the glass waveguide 113. In order to confine this incident light in the glass waveguide 113, a mirror 232 made of metal may be disposed on the upper surface of the glass waveguide 113.

[0075] 8A and 8B, a crystal orientation plane (facet) 241 formed by wet etching the silicon substrate 111 may be used as a mirror. Considering that the angle 242 of the crystal orientation plane 241 with the horizontal plane is approximately 55 degrees, the position of the crystal orientation plane (mirror) 241 is designed so that the resin curing light 15 reflected by this crystal orientation plane (mirror) 241 enters the glass waveguide 113. To confine the resin curing light 15 within the glass waveguide 113, a metal mirror 243 may be placed on the upper surface of the glass waveguide 113.

[0076] Furthermore, if processing is difficult in an LD chip or the like, a separate mirror 251 may be placed on the substrate 111 as shown in Figures 9A and 9B. This causes the resin curing light 15 from above to be reflected in a direction at an angle of about 90 degrees to the incident direction, eliminating the need to consider the light path of the light-receiving light-guiding section. Here, the process conditions are adjusted so that the mirror 251 does not come off during spin coating and can be removed after exposure and development.

[0077] <Second embodiment> An optical connection structure and a manufacturing method thereof according to a second embodiment of the present invention will be described with reference to FIGS. 10A to 12B.

[0078] In the first embodiment, an example was shown in which a first optical element (PLC chip) and a second optical element (LD chip) are mounted, and then a self-written waveguide 131 is formed and connected. The optical connection structure 20 according to this embodiment differs in that a self-written waveguide 131 is formed on one of the chips (PLC chip), and then the structure of the self-written waveguide 131 is used to improve positional accuracy. The other configurations are the same as those of the first embodiment.

[0079] <Configuration of optical connection structure> As shown in FIGS. 10A to 10D, the optical connection structure 20 includes a PLC chip 11, an LD chip 12, and a self-written waveguide 131 between the PLC chip 11 and the LD chip 12.

[0080] 11, the LD end face of the LD chip 12 is provided with a groove 31 having openings 311 and 312 on the top surface and LD end face of the LD chip 12, respectively. The groove 31 is fitted with a self-written waveguide 131. The LD chip 12 does not require a substrate. The other configurations are the same as those of the first embodiment.

[0081] <Method of manufacturing optical connection structure> A method for manufacturing the optical connection structure 20 according to this embodiment will be described with reference to FIGS. 10A to 12B.

[0082] First, as shown in FIGS. 10A and 10B, after the PLC chip 11 is formed, and before the LD chip 12 is mounted, a self-written waveguide 131 connected to the PLC chip 11 is formed with an appropriate length.

[0083] 10C and 10D, the LD chip 12 is mounted so that the SiN waveguide end facet 127 is connected to the self-written waveguide 131. Here, the LD chip 12 is mounted by a wafer bonding method or the like on a layer structure including an LD active layer 126 other than the substrate, an InP waveguide 125, a SiN waveguide 123, and a cladding. Here, the LD chip 12 does not need to be provided with a second light-receiving light-guiding section 124.

[0084] 11, the LD chip 12 has a groove 31. An SiN waveguide end face 127 is exposed on the side surface of the groove 31 that is parallel to the LD end face.

[0085] The self-written waveguide 131 is fitted (inserted) into the groove 31 of the LD chip 12 to connect the exposed portion of the LD chip 12 to the self-written waveguide 131. At this time, the chip is mounted and bonded using image recognition in combination.

[0086] 12A and 12B, the LD chip 12 may be mounted with the opening 311 on the upper surface of the groove 31 facing the substrate 111. This improves the margin for alignment in the vertical direction (the direction perpendicular to the substrate surface) during mounting compared to when the LD chip 12 is mounted with the opening 311 on the upper surface of the groove 31 facing upward (opposite the substrate 111).

[0087] At this time, by making the LD chip 12 from which the substrate has been removed into a thin film that allows visible light to pass through, the LD chip 12 can be mounted close to the self-written waveguide 131 from above using image recognition.

[0088] Furthermore, if a manufacturing error occurs in the vertical direction, good optical connection can be obtained by bending (or curving) the self-written waveguide 131 toward the substrate within a range that does not cause the self-written waveguide 131 to be destroyed.

[0089] According to the optical connection structure of this embodiment, by fitting the self-written waveguide 131 formed in one optical element (PLC chip) 11 with the groove 31 formed in the other optical element (LD chip) 12, a high-precision optical connection can be made, and one optical element (PLC chip) 11 and the other optical element (LD chip) 12 can be mounted.

[0090] <Third embodiment> An optical connection structure according to a third embodiment of the present invention will be described with reference to FIGS. 13A to 13G.

[0091] In the first embodiment, an example was shown in which a chip is mounted and then a self-written waveguide 131 is formed and connected. The optical connection structure according to this embodiment is different in that a self-written waveguide 131 is formed on one of the chips (LD chip), and then the positional accuracy is improved using the structure of the self-written waveguide 131. Other configurations are the same as those in the first embodiment.

[0092] <Configuration of optical connection structure> As shown in Fig. 13G, the optical connection structure includes a PLC chip 11, an LD chip 12, and a self-written waveguide 131 between the PLC chip 11 and the LD chip 12. Here, a groove 41 having openings on the top surface and the PLC end surface of the PLC chip 11 is provided on the PLC end surface of the PLC chip 11. The groove 41 is fitted with the self-written waveguide 131. The other configurations are the same as those of the first embodiment.

[0093] <Method of manufacturing optical connection structure> First, the LD chips 12 are periodically arranged on the wafer and formed in a batch, and then the substrate 121 is half-cut along the scribe lines with a dicing device to form LD wafer grooves 42 .

[0094] Next, similar to the manufacturing process in the first embodiment, resin curing light 15 is incident from second light-receiving and guiding section 124, emitted from SiN waveguide end face 127, and irradiated onto photocurable resin 14 filled in LD wafer groove 42. This hardens the resin to form self-written waveguide 131 of an appropriate length. Next, the unhardened portion around self-written waveguide 131 is removed (FIGS. 13A and 13B).

[0095] Next, the LD chips 12 are separated into individual pieces by cleavage or the like (FIG. 13C).

[0096] 13D and 13E, a PLC chip 11 is formed on a wafer, and a groove 41 is formed in the PLC end surface. Here, the groove 41 has openings in the PLC end surface and the top surface of the PLC chip 11.

[0097] The top surface of the LD chip 12 is turned (flipped) toward the substrate 111, the self-written waveguide 131 is fitted into the groove 41 on the PLC end surface, and the LD chip 12 is mounted and bonded to the recess 115 of the wafer (FIGS. 13F and 13G).

[0098] At this time, the position of the SiN waveguide 123 on the LD chip 12 side cannot be directly grasped by image recognition from the back surface (substrate 121 side) of the LD chip 12, but since the self-formed waveguide 131 protrudes from the LD end face, the position of the SiN waveguide 123 can be detected by image recognition.

[0099] Furthermore, the self-written waveguide 131 fits into the recessed groove 41, thereby improving the structural positional accuracy.

[0100] According to the optical connection structure of this embodiment, by fitting the self-written waveguide 131 formed on one chip into the recess formed on the other chip, it is possible to mount one chip and the other chip through high-precision optical connection. Furthermore, when performing image recognition from the substrate side of the mounted chip, the self-written waveguide 131 protruding from the chip end allows the position of the waveguide of the mounted chip to be grasped and image recognized.

[0101] In the embodiments of the present invention, examples of the structure, dimensions, materials, etc. of each component in the configuration and manufacturing method of the optical connection structure are shown, but the present invention is not limited to these examples. Anything that can demonstrate the function and effect of the optical connection structure may be used. [Industrial Applicability]

[0102] The present invention relates to an optical connection structure, and can be applied to equipment and systems for optical communications and the like. [Explanation of symbols]

[0103] 10 Optical connection structure 11 First optical element 111 first substrate 113 First Waveguide 114 First light receiving guide 12 Second optical element 123 Second Waveguide 131 Self-formed waveguide

Claims

1. A method for manufacturing an optical connection structure for optically connecting a first optical element having a first optical waveguide and a first light-receiving light-guiding portion disposed at the other end of the first optical waveguide, and a second optical element having a second optical waveguide and a second light-receiving light-guiding portion disposed at the other end of the second optical waveguide, the method comprising: forming a plurality of the first optical elements collectively and periodically at predetermined intervals on a first wafer substrate; forming a plurality of recesses in contact with the plurality of first optical elements, respectively, on the first wafer substrate; a step of forming a plurality of the second optical elements collectively on a second substrate to form the second optical elements into chips; a step of arranging each of the plurality of second optical elements in the plurality of recesses so that an end face of the first optical waveguide and an end face of the second optical waveguide are close to each other, and fixing the first optical element and the second optical element; filling a space between an end face of the first optical waveguide and an end face of the second optical waveguide with a photocurable resin; a step of collectively forming a plurality of self-forming waveguides that connect the first optical waveguides of the plurality of first optical elements to the second optical waveguides of the plurality of second optical elements, by collectively directing resin curing light through openings in an exposure mask to the first light-receiving and guiding portions of the plurality of first optical elements and the second light-receiving and guiding portions of the plurality of second optical elements, converting the wave-guiding direction of the resin curing light to the horizontal direction of the first wafer substrate, directing the resin curing light to the first optical waveguide, guiding the resin curing light to the first optical waveguide, and irradiating the photocurable resin; forming a cladding around the self-written waveguide, the cladding having a refractive index lower than that of the self-written waveguide; Equipped with The openings of the exposure mask are periodically arranged at the predetermined intervals.

10. A method for manufacturing an optical connection structure comprising:

2. The exposure mask has a diffraction grating at the opening.

2. The method for manufacturing an optical connection structure according to claim 1.

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