JP2025124060A - Optical module and method for manufacturing the optical module - Google Patents

Abstract

To fix an optical semiconductor element to a base material using a thermally curable material of high heat dissipation property while keeping a position of the optical semiconductor element after optical axis adjustment.SOLUTION: An optical module comprises a base material, an optical semiconductor element, an optical circuit element, a first adhesive, and a second adhesive. The base material includes a first face. The optical semiconductor element includes a first optical port, through which light is incident and emitted or incident/emitted, on a side face and is provided on the first face. The optical circuit element includes a second optical port, through which light is incident and emitted or incident/emitted and which is opposed and optically coupled with the first optical port, on a side face. The optical circuit element is disposed on the first face in parallel with the optical semiconductor element. The first adhesive mainly contains a UV curable material and has first heat conductivity. The first adhesive is disposed between the optical semiconductor element and the first face and fixes the optical semiconductor element to the first face. The second adhesive mainly contains a thermally curable material and has second heat conductivity that is higher than the first heat conductivity. The second adhesive fixes the optical semiconductor element to the first face.SELECTED DRAWING: Figure 2

Description

This disclosure relates to an optical module and a method for manufacturing an optical module.

Patent Document 1 discloses a flip-chip connection method. This method includes a first step and a second step. In the first step, a conductive paste is transferred to bumps on a semiconductor chip. In the second step, the bumps are connected to a conductive pattern on a substrate, and portions of the semiconductor chip where no bumps are formed are adhered to the substrate with an adhesive sealing resin.

Patent Document 2 discloses a light-emitting device. This light-emitting device includes a semiconductor light-emitting element, a conductive member, a conductive paste, and a fixing resin. The conductive paste electrically connects the electrodes of the semiconductor light-emitting element to the conductive member. The fixing resin covers the lower side surface of the semiconductor light-emitting element and the portion of the bottom surface where the conductive paste is not applied, and fixes the semiconductor light-emitting element to the conductive member.

Patent Document 3 discloses a semiconductor device. This semiconductor device includes a semiconductor element, a support, sintered silver that bonds the semiconductor element to the support, and a resin that bonds the semiconductor element to the support. The resin is formed in at least a portion of a contoured region that follows the contour of the semiconductor element.

Japanese Patent Application Laid-Open No. 2000-236002 Japanese Patent Application Laid-Open No. 2006-108238 Japanese Patent Application Laid-Open No. 2017-092389 Special Publication No. 2022-522796

In some cases, an optical semiconductor element with an optical port on its side is fixed to a substrate after its optical axis is adjusted relative to an optical circuit element with another optical port on its side. To dissipate heat from the optical semiconductor element, it is desirable to fix the optical semiconductor element to the substrate using a thermosetting material with good thermal conductivity, such as sintered silver. However, extremely high temperatures are required to harden thermosetting materials, such as sintered silver. Therefore, it is difficult to harden the thermosetting material while holding the optical semiconductor element with its optical axis adjusted using a chuck or similar device. Furthermore, when fixing the optical semiconductor element to the substrate using a UV-curing material, such as UV-curing resin, it is easy to irradiate the UV-curing material with ultraviolet light while holding the optical semiconductor element with its optical axis adjusted using a chuck or similar device, which allows the UV-curing material to harden easily. However, in this case, there is a risk that the heat dissipation from the optical semiconductor element will be insufficient due to the low thermal conductivity of the UV-curing material.

The present disclosure aims to provide an optical module and a method for manufacturing the optical module that can fix an optical semiconductor element to a substrate using a thermosetting material with high heat dissipation properties while maintaining the position of the optical semiconductor element after optical axis adjustment.

An optical module according to one embodiment of the present disclosure includes a substrate, an optical semiconductor element, an optical circuit element, a first adhesive, and a second adhesive. The substrate has a first surface. The optical semiconductor element is provided on the first surface and has a first optical port on a side surface for light incidence, emission, or light ingress/egress. The optical circuit element has a second optical port on a side surface for light incidence, emission, or light ingress/egress and optically coupled opposite the first optical port. The optical circuit element is disposed on the first surface alongside the optical semiconductor element. The first adhesive primarily contains a UV-curable material and has a first thermal conductivity. The first adhesive is disposed between the optical semiconductor element and the first surface and fixes the optical semiconductor element to the first surface. The second adhesive primarily contains a thermosetting material and has a second thermal conductivity higher than the first thermal conductivity. The second adhesive is disposed between the optical semiconductor element and the first surface and fixes the optical semiconductor element to the first surface.

This disclosure provides an optical module and a method for manufacturing an optical module that can fix an optical semiconductor element to a substrate using a thermosetting material with high heat dissipation properties while maintaining the position of the optical semiconductor element after optical axis adjustment.

FIG. 1 is a perspective view of an optical module according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view of the optical module taken along line II-II in FIG. FIG. 3 is a flowchart showing a method for manufacturing an optical module according to this embodiment. FIG. 4 is a cross-sectional view of an optical module according to a modification of the above embodiment. FIG. 5 is a plan view showing the substrate, the first adhesive, and the second adhesive. FIG. 6 is a cross-sectional view showing a second step in the manufacturing process of the optical module. FIG. 7 is a cross-sectional view showing a second step in the manufacturing process of the optical module. FIG. 8 is a cross-sectional view showing a second step in the manufacturing process of the optical module. FIG. 9 is a plan view showing a base material, a first adhesive, and a second adhesive according to another modified example. FIG. 10 is a cross-sectional view of an optical module according to a third modified example. FIG. 11 is a perspective view showing the appearance of a carrier according to a third modified example. FIG. 12 is a diagram for explaining the problems that the optical module has. FIG. 13 is a cross-sectional view showing how the spread portion of the first adhesive is blocked by a step. FIG. 14 is a perspective view showing the appearance of a carrier as another form of the third modified example. FIG. 15 is a cross-sectional view of an optical module according to a fourth modification. FIG. 16 is a perspective view showing the appearance of a carrier according to a fourth modified example. FIG. 17 is a cross-sectional view showing how the first adhesive is prevented from spreading to the second contact surface. FIG. 18 is a perspective view showing the appearance of a carrier as another form of the fourth modified example. FIG. 19 is a cross-sectional view of an optical module according to a fifth modified example.

Description of the embodiments of the present disclosure
First, the contents of the embodiments of the present disclosure will be listed and described. [1] An optical module according to one embodiment of the present disclosure includes a substrate, an optical semiconductor element, an optical circuit element, a first adhesive, and a second adhesive. The substrate has a first surface. The optical semiconductor element has a first optical port on a side surface for light incidence, emission, or input/output, and is provided on the first surface. The optical circuit element has a second optical port on a side surface for light incidence, emission, or input/output, and is optically coupled to the first optical port opposite the first optical port. The optical circuit element is disposed on the first surface alongside the optical semiconductor element. The first adhesive mainly contains a UV-curable material and has a first thermal conductivity. The first adhesive is disposed between the optical semiconductor element and the first surface and fixes the optical semiconductor element to the first surface. The second adhesive mainly contains a thermosetting material and has a second thermal conductivity higher than the first thermal conductivity. The second adhesive is disposed between the optical semiconductor element and the first surface and fixes the optical semiconductor element to the first surface.

In the optical module [1] above, the optical semiconductor element is fixed to the first surface of the substrate using a first adhesive and a second adhesive. The first adhesive primarily contains a UV-curable material and has a first thermal conductivity. The second adhesive primarily contains a thermosetting material and has a second thermal conductivity higher than the first thermal conductivity of the first adhesive. When manufacturing this optical module, the position of the optical semiconductor element after optical axis adjustment can be maintained using a chuck or the like while irradiating it with ultraviolet light to harden the first adhesive. Thereafter, with the position of the optical semiconductor element after optical axis adjustment maintained by the first adhesive, the second adhesive can be hardened by heating. Therefore, with the optical module [1] above, the optical semiconductor element can be fixed to the substrate using a highly heat-dissipating thermosetting material while maintaining the position of the optical semiconductor element after optical axis adjustment.

[2] In the optical module of [1] above, the optical semiconductor element may include an optical semiconductor chip having a first optical port and a carrier carrying the optical semiconductor chip and fixed to the first surface with a first adhesive and a second adhesive. In this case, even if the thickness of the optical semiconductor chip is smaller than the thickness of the optical circuit element, the height of the first optical port can be adjusted to match the height of the second optical port.

[3] In the optical module of [1] or [2] above, the UV-curable material may be a UV-curable resin. In this case, the optical semiconductor element can be easily fixed to the substrate.

[4] In the optical modules described in [1] to [3] above, the thermosetting material may be sintered silver. Sintered silver has extremely high thermal conductivity, so in this case, heat from the optical semiconductor element can be efficiently transferred to the substrate.

[5] In the optical modules described in [1] to [3] above, the thermosetting material may be epoxy-containing sintered silver. By including epoxy-containing sintered silver in the second adhesive, shrinkage of the second adhesive during sintering can be suppressed, making the second adhesive less likely to peel off from the optical semiconductor element.

[6] In the optical modules described above in [1] to [5], the first adhesive and the second adhesive may be spaced apart from each other on the first surface. In this case, mixing of the first adhesive and the second adhesive before curing is avoided. This prevents the second adhesive from interfering with the curing of the first adhesive.

[7] In the optical modules described in [1] to [6] above, the substrate may have a recess formed between the first adhesive and the second adhesive when viewed from the normal direction of the first surface. Variations in the height from the bottom surface of the optical semiconductor element to the first optical port occur due to manufacturing errors. Because the height position of the first optical port is determined by the height position of the second optical port of the optical circuit element, variations in the height from the bottom surface of the optical semiconductor element to the first optical port are absorbed by the thickness of the first adhesive and the second adhesive. When the thicknesses of the first adhesive and the second adhesive are small, the first adhesive and the second adhesive spread laterally (along the first surface) and approach each other. By having a recess formed between the first adhesive and the second adhesive in the substrate, the first adhesive and the second adhesive that spread in the approaching direction can be dropped into the recess. This prevents the first adhesive and the second adhesive from mixing on the first surface before curing, thereby preventing the second adhesive from interfering with the curing of the first adhesive on the first surface.

[8] The optical modules described in [1] to [7] above may further include a third adhesive disposed between the first optical port and the second optical port, the third adhesive primarily containing a UV-curable material that cures faster than the UV-curable material of the first adhesive. In this case, the third adhesive cures faster than the first adhesive when irradiated with ultraviolet light. This allows the optical coupling between the first optical port and the second optical port to be maintained more firmly after optical axis adjustment.

[9] In the optical modules described above in [1] to [8], the contact area between the second adhesive and the optical semiconductor element may be larger than the contact area between the first adhesive and the optical semiconductor element. In this case, heat from the optical semiconductor element can be transferred to the substrate more efficiently.

[10] In the optical modules described in [1] to [9] above, the first adhesive may be provided on multiple areas of the first surface that sandwich the second adhesive. In this case, when the second adhesive is cured by heating, the position of the first optical port can be more stably maintained after the optical axis is adjusted.

[11] In the optical module of [10] above, the arrangement of the multiple regions may be symmetrical with respect to an axis along the first surface. In this case, the position of the first optical port can be maintained more stably after the optical axis is adjusted.

[12] In the optical modules described above in [1] to [11], the optical semiconductor element may have a bottom surface facing the first surface. The first adhesive and the second adhesive may be spaced apart on the bottom surface of the optical semiconductor element. In this case, mixing of the first adhesive and the second adhesive before curing is avoided. This prevents the second adhesive from interfering with the curing of the first adhesive.

[13] In the optical modules [2] to [12] above, the carrier may have a bottom surface facing the first surface. The bottom surface may include a first contact surface with which the first adhesive contacts and a second contact surface with which the second adhesive contacts. The distance between the second contact surface and the first surface may be smaller than the distance between the first contact surface and the first surface. In this case, even if the uncured first adhesive spreads along the bottom surface of the carrier, the spread portion of the first adhesive is blocked by the step between the first and second contact surfaces, preventing the first adhesive from spreading toward the second contact surface. Therefore, the optical module [13] above can prevent the first adhesive and the second adhesive from mixing on or near the bottom surface of the carrier, and can prevent the second adhesive from interfering with the curing of the first adhesive on or near the bottom surface of the carrier. Furthermore, the first adhesive is prevented from entering between the second adhesive and the bottom surface of the carrier, and the area of the second contact surface can be increased, thereby improving heat dissipation.

[14] In the optical module of [13] above, the bottom surface of the carrier may further have a third contact surface with which the first adhesive comes into contact. When viewed from the normal direction of the bottom surface of the carrier, the first contact surface may be located between the second contact surface and the third contact surface. The distance between the third contact surface and the first surface may be smaller than the distance between the first contact surface and the first surface. In this case, the portion of the first adhesive located on the side surface of the carrier and the portion of the first adhesive located on the first contact surface sandwich part of the carrier, i.e., the portion sandwiched between the side surface of the carrier and the first contact surface, from both sides. This increases the fixing strength between the carrier and the substrate.

[15] In the optical module of [13] above, the bottom surface of the carrier may further have a third contact surface with which the first adhesive comes into contact. When viewed from the normal direction of the bottom surface of the carrier, the first contact surface may be located between the second contact surface and the third contact surface. The distance between the third contact surface and the first surface may be greater than the distance between the first contact surface and the first surface. In this case, the spread portion of the first adhesive before hardening is further blocked by the step between the first contact surface and the third contact surface. Therefore, the first adhesive is more effectively prevented from spreading onto the second contact surface.

[16] A method for manufacturing an optical module according to one embodiment of the present disclosure includes a first placing step, a second placing step, a first adhesive curing step, and a second adhesive curing step. In the first placing step, an optical circuit element having a second optical port on its side surface for light incidence, emission, or ingress/egress, a first adhesive containing primarily a UV-curable material and having a first thermal conductivity, and a second adhesive containing primarily a thermosetting material and having a second thermal conductivity higher than the first thermal conductivity, are placed on a first surface of a substrate. In the second placing step, an optical semiconductor element having a first optical port on its side surface for light incidence, emission, or ingress/egress, is placed. In the second placing step, the position of the optical semiconductor element is adjusted while in contact with the first adhesive and the second adhesive so that the first optical port is optically coupled to the second optical port. Such adjustment may be performed by an active alignment method or a passive alignment method. In the step of hardening the first adhesive, the optical semiconductor element is held in a position adjusted to allow for the optical coupling, and the first adhesive is hardened by irradiation with ultraviolet light. In the step of hardening the second adhesive, the second adhesive is hardened by heating while the first adhesive is in a hardened state.

In the manufacturing method [16] above, the optical semiconductor element is fixed to the first surface of the substrate using a first adhesive and a second adhesive. The first adhesive primarily contains a UV-curable material. The second adhesive has a second thermal conductivity higher than the first thermal conductivity of the first adhesive and primarily contains a thermosetting material. In the step of curing the first adhesive, the first adhesive can be cured by irradiating it with ultraviolet light while maintaining the position of the optical semiconductor element after optical axis adjustment using a chuck or the like. Thereafter, in the step of curing the second adhesive, the second adhesive can be cured by heating while the position of the optical semiconductor element after optical axis adjustment is maintained by the first adhesive. Therefore, according to the manufacturing method [16] above, the optical semiconductor element can be fixed to the substrate using a thermosetting material with high heat dissipation properties while maintaining the position of the optical semiconductor element after optical axis adjustment.
[Details of the embodiment of the present disclosure]

Specific examples of the present disclosure are described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications that are equivalent in meaning and scope to the claims. In the following description, identical elements in the description of the drawings will be designated by the same reference numerals, and duplicate explanations will be omitted.

Figure 1 is a perspective view of an optical module 1A according to one embodiment of the present disclosure. Figure 2 is a cross-sectional view of the optical module 1A taken along line II-II in Figure 1. As shown in Figures 1 and 2, the optical module 1A of this embodiment comprises a substrate 10A, an optical semiconductor element 20, an optical circuit element 30, a first adhesive 40, a second adhesive 50, and a third adhesive 60. Note that the first adhesive 40, the second adhesive 50, and the third adhesive 60 are shown schematically in Figure 1.

The substrate 10A has a flat first surface 11. While the figure shows the first surface 11 as having a rectangular planar shape as an example, the planar shape of the first surface 11 is not limited to this. The substrate 10A is, for example, an insulating substrate. A metal film is formed on the first surface 11 to be bonded to the second adhesive 50.

The optical semiconductor element 20 is provided on the first surface 11. The optical semiconductor element 20 has a first optical port 20a on its side surface 21, through which light is incident, emitted, or both incident and emitted. The optical semiconductor element 20 in the illustrated example includes an optical semiconductor chip 22 and a carrier 23. The optical semiconductor chip 22 has an end surface that constitutes the side surface 21 and has the first optical port 20a on that end surface. The optical semiconductor chip 22 is, for example, a semiconductor optical amplifier (SOA). The optical semiconductor chip 22 is made of a compound material such as indium phosphide (InP). The carrier 23 has a roughly rectangular parallelepiped appearance and has a mounting surface 23a and a bottom surface 23b facing away from the mounting surface 23a. The optical semiconductor chip 22 is mounted on the mounting surface 23a. The bottom surface 23b faces the first surface 11. The bottom surface 23b also serves as the bottom surface of the optical semiconductor element 20. In this embodiment, the bottom surface 23b is flat. The carrier 23 is made of a ceramic material, such as aluminum nitride (AlN), with a metal film, such as a gold (Au) film, formed on its surface. The back electrode of the optical semiconductor chip 22 is conductively bonded to the metal film provided on the mounting surface 23a of the carrier 23.

The optical circuit element 30 is arranged on the first surface 11 alongside the optical semiconductor element 20. For example, the optical circuit element 30 is fixed to the first surface 11 with an adhesive (not shown). The optical circuit element 30 is, for example, a silicon photonics chip (SiPh) with an optical circuit formed on its main surface 31. The optical circuit element 30 has a second optical port 30a on its side surface 32, through which light is incident, emitted, or both. The second optical port 30a faces the first optical port 20a and is optically coupled to the first optical port 20a. Only a third adhesive 60 (or air if the third adhesive 60 is not provided) exists between the first optical port 20a and the second optical port 30a; no optical components such as lenses are provided between the first optical port 20a and the second optical port 30a (so-called edge coupling). The distance between the first optical port 20a and the second optical port 30a is, for example, several micrometers.

As an example, the optical circuit element 30 further includes a linear optical waveguide 33, a built-in photodiode 34, and a monitor optical port 30b. The optical waveguide 33 is formed on the main surface 31. The first end of the optical waveguide 33 is the second optical port 30a. The second end of the optical waveguide 33 is the reflecting end 33a. Light introduced through the second optical port 30a is reflected at the reflecting end 33a and emitted from the second optical port 30a. As a result, the optical waveguide 33, together with the optical waveguide inside the optical semiconductor chip 22, forms a laser resonator. Note that a spot size converter may be provided between the second optical port 30a and the first end of the optical waveguide 33. The laser light generated by the optical semiconductor chip 22 and the optical waveguide 33 is emitted to the outside of the optical module 1A, for example, from an optical port (not shown) on the optical semiconductor chip 22 opposite the first optical port 20a.

The built-in photodiode 34 is formed on the main surface 31. The built-in photodiode 34 is optically coupled to the optical waveguide 33 via an optical waveguide 35 formed on the main surface 31. The built-in photodiode 34 outputs an electrical signal corresponding to the optical intensity of the laser light generated within the optical waveguide 35. For example, a control device provided outside the optical module 1A controls the gain of the optical semiconductor element 20 based on the electrical signal. The monitor optical port 30b is optically coupled to the optical waveguide 33 via an optical waveguide 36 formed on the main surface 31. A portion of the laser light generated within the optical waveguide 35 is provided to the outside of the optical module 1A from the monitor optical port 30b.

The first adhesive 40 is disposed between the optical semiconductor element 20 and the first surface 11. In the illustrated example, the first adhesive 40 is disposed between the bottom surface 23b of the carrier 23 and the first surface 11, and is in contact with both the bottom surface 23b and the first surface 11. That is, the bottom surface 23b of the carrier 23 includes a first contact surface 23ba with which the first adhesive 40 comes into contact. The first adhesive 40 may also be in contact with the side surface of the carrier 23. The first adhesive 40 primarily contains a UV-curable material that hardens when exposed to ultraviolet (UV) light. The UV-curable material may be a UV-curable resin. The first adhesive 40 secures the optical semiconductor element 20 (carrier 23 in the illustrated example) to the first surface 11. The thickness of the first adhesive 40 (in other words, the distance between the bottom surface 23b of the carrier 23 and the first surface 11) is, for example, 20 μm or more and 70 μm or less when the first adhesive 40 is hardened. The first adhesive 40 has thermal conductivity (first thermal conductivity). The first thermal conductivity of the first adhesive 40 after hardening may be less than 1 W/m·K.

The second adhesive 50 is disposed alongside the first adhesive 40 on the first surface 11 and is disposed between the optical semiconductor element 20 and the first surface 11. In the illustrated example, the second adhesive 50 is disposed between the bottom surface 23b of the carrier 23 and the first surface 11, and is in contact with both the bottom surface 23b and the first surface 11 (more specifically, both the metal films formed on the bottom surface 23b and the first surface 11, respectively). That is, the bottom surface 23b of the carrier 23 includes a second contact surface 23bb with which the second adhesive 50 contacts. The second adhesive 50 may also be in contact with the side surface of the carrier 23 (more specifically, the metal film formed on the side surface of the carrier 23). The second adhesive 50 primarily contains a thermosetting material that hardens when heated. The thermosetting material may be sintered silver or epoxy-containing sintered silver. The second adhesive 50 has a higher thermal conductivity (second thermal conductivity) than the thermal conductivity (first thermal conductivity) of the first adhesive 40. The second thermal conductivity of the second adhesive 50 after curing may be greater than 20 W/m·K. The second thermal conductivity may be greater than 20 times the first thermal conductivity. Sintered silver has a thermal conductivity greater than 100 W/m·K. The second thermal conductivity may be greater than 100 times the first thermal conductivity. The second adhesive 50 secures the optical semiconductor element 20 (carrier 23 in the illustrated example) to the first surface 11. Furthermore, the second adhesive 50 conducts heat generated within the optical semiconductor element 20 to the substrate 10A more efficiently than the first adhesive 40.

As shown in FIG. 2, the first adhesive 40 and the second adhesive 50, after curing, are not in contact with each other on the first surface 11 (or on the bottom surface 23b of the carrier 23), but are spaced apart. After curing, the width of the gap between the first adhesive 40 and the second adhesive 50 is, for example, 0.05 mm or more and, for example, 0.25 mm or less. The contact area between the second adhesive 50 and the optical semiconductor element 20 (carrier 23 in the illustrated example) is larger than the contact area between the first adhesive 40 and the optical semiconductor element 20 (carrier 23 in the illustrated example).

The third adhesive 60 is disposed between the first optical port 20a and the second optical port 30a and contacts both the first optical port 20a and the second optical port 30a. The third adhesive 60 may also contact one or both of the top surface of the optical semiconductor element 20 (the top surface of the optical semiconductor chip 22 in the illustrated example) and the main surface 31 of the optical circuit element 30. The third adhesive 60 primarily contains a UV-curable material that cures faster than the UV-curable material of the first adhesive 40. The UV-curable material may be a UV-curable resin. The third adhesive 60 is translucent to light propagating between the first optical port 20a and the second optical port 30a and provides refractive index matching between the first optical port 20a and the second optical port 30a. The third adhesive 60 may be, for example, an epoxy-based resin, and may have a refractive index of 1.4 to 1.6 after curing. The optical semiconductor chip 22 protrudes toward the optical circuit element 30 in the X direction beyond the side surface 23c of the carrier 23 facing the optical circuit element 30. Therefore, in the X direction, the side surface 21 of the optical semiconductor chip 22 is located between the side surface 23c of the carrier 23 and the optical circuit element 30. The optical semiconductor element 20 has a distance OH between the side surface 21 of the optical semiconductor chip 22 and the side surface 23c of the carrier 23 in the X direction. Providing an overhang of distance OH prevents the second adhesive 50 from coming into contact with the third adhesive 60 when it creeps up the side surface 23c toward the optical semiconductor chip 22 in the Z direction. The distance OH may be, for example, 0.05 mm or more, or even 0.1 mm or less.

Figure 3 is a flowchart showing a method for manufacturing the optical module 1A according to this embodiment. As shown in Figure 3, this manufacturing method includes a first step ST1, a second step ST2, a third step ST3, a fourth step ST4, and a fifth step ST5. In the first step ST1, the optical circuit element 30, the first adhesive 40, and the second adhesive 50 are placed on the first surface 11 of the substrate 10A. At this time, the first adhesive 40 and the second adhesive 50 are applied to the first surface 11. The thickness of the first adhesive 40 and the second adhesive 50 at this time, in other words, the height from the first surface 11 to each apex of the first adhesive 40 and the second adhesive 50, is, for example, 70 μm or more, and in one example, 100 μm. This height represents the height before the optical axis adjustment described below is performed.

In the second step ST2, the optical semiconductor element 20 is gripped with a chuck or the like. A drive current is then supplied to the optical semiconductor element 20 via the chuck or the like, causing light to be emitted from the first optical port 20a of the optical semiconductor element 20. While the optical semiconductor element 20 (specifically, the bottom surface 23b of the carrier 23) is brought into contact with the first adhesive 40 and the second adhesive 50, the position and angle of the optical semiconductor element 20 are adjusted (optical axis adjustment) so that the first optical port 20a is optically coupled with the second optical port 30a. The optical coupling state between the first optical port 20a and the second optical port 30a can be determined, for example, by detecting the magnitude of the electrical signal output from the built-in photodiode 34 or the intensity of the light emitted from the monitor optical port 30b. Adjustments to the position and angle of the optical semiconductor element 20 include adjustment of the position in the optical axis direction (arrow A1 shown in FIG. 1 ), adjustment of the position in the lateral direction intersecting the optical axis direction (arrow A2), adjustment of the position in the normal direction to the first surface 11 (arrow A3), and adjustment of the angle around the axis normal to the first surface 11 (arrow A4). Optical axis adjustment is performed so that the magnitude of the electrical signal output from the built-in photodiode 34 or the intensity of the light emitted from the monitor optical port 30b exceeds a predetermined value. Adjusting the position in the normal direction to the first surface 11 during optical axis adjustment can change the thickness of the first adhesive 40 and the second adhesive 50. Before hardening, the first adhesive 40 and the second adhesive 50 can easily deform due to external forces. For convenience, in the following description, the optical axis direction is sometimes referred to as the X direction, the lateral direction intersecting the optical axis direction as the Y direction, and the height direction intersecting the X and Y directions as the Z direction.

In the third step ST3, the optical semiconductor element 20 after optical axis adjustment is held in a position adjusted to allow for the optical coupling described above using a chuck or the like, and the position and angle of the optical semiconductor element 20 are maintained. Then, in the fourth step ST4, the first adhesive 40 and the third adhesive 60 are cured by irradiating them with ultraviolet light while the optical semiconductor element 20 after optical axis adjustment is held in a position adjusted to allow for the optical coupling described above using a chuck or the like, and the position and angle of the optical semiconductor element 20 are maintained. As described above, the third adhesive 60 primarily contains a UV-curable material that cures faster than the UV-curable material of the first adhesive 40. Therefore, the third adhesive 60 cures faster than the first adhesive 40. When curing the third adhesive 60, the exposed area around the first adhesive 40 may be temporarily covered with a shield to prevent ultraviolet light from reaching the first adhesive 40.

In the fifth step ST5, with the first adhesive 40 and the third adhesive 60 in a cured state, the second adhesive 50 is cured (sintered) by heating. In this fifth step ST5, multiple work-in-progress items that have been processed up to the fourth step ST4 may be placed in a heating furnace, and the second adhesive 50 of the multiple work-in-progress items may be cured collectively. Through these steps, the optical module 1A of this embodiment is manufactured.

The following describes the effects achieved by the optical module 1A and manufacturing method thereof according to the present embodiment. In the optical module 1A according to the present embodiment, the optical semiconductor element 20 is fixed to the first surface 11 of the substrate 10A by the first adhesive 40 and the second adhesive 50. The first adhesive 40 primarily contains a UV-curable material and has a thermal conductivity (first thermal conductivity). The second adhesive 50 primarily contains a thermosetting material and has a thermal conductivity (second thermal conductivity) higher than that of the first adhesive 40 (first thermal conductivity). When manufacturing this optical module 1A, the optical axis is adjusted while the first adhesive 40 and the second adhesive 50 are deformable. The position of the optical semiconductor element 20 after the optical axis adjustment is maintained by a chuck or the like, and ultraviolet light is irradiated to harden the first adhesive 40. Then, while the position of the optical semiconductor element 20 after the optical axis adjustment is maintained by the first adhesive 40, the second adhesive 50 can be hardened by heating. Therefore, with the optical module 1A of this embodiment, the optical semiconductor element 20 can be fixed to the base 10A using a thermosetting material with high heat dissipation properties while maintaining the position of the optical semiconductor element 20 after optical axis adjustment. As a result, it is possible to prevent optical axis misalignment between the first optical port 20a and the second optical port 30a when the second adhesive 50 is thermally cured, while improving heat dissipation from the optical semiconductor element 20 to the base 10A. The thermal resistance from the bottom surface 23b of the carrier 23 to the first surface 11 is, for example, 5 K/W or less.

As in this embodiment, the optical semiconductor element 20 may include an optical semiconductor chip 22 having a first optical port 20a, and a carrier 23 on which the optical semiconductor chip 22 is mounted and fixed to the first surface 11 by a first adhesive 40 and a second adhesive 50. In this case, even if the thickness of the optical semiconductor chip 22 is smaller than the thickness of the optical circuit element 30, the height of the first optical port 20a can be adjusted to match the height of the second optical port 30a.

As mentioned above, the UV-curable material may be a UV-curable resin. In this case, the optical semiconductor element 20 can be easily fixed to the substrate 10A after adjusting the optical axis. This allows the optical semiconductor element 20 to be fixed to the substrate 10A with sufficient strength using the first adhesive 40. As a result, it is possible to prevent misalignment of the optical axis between the first optical port 20a and the second optical port 30a when the second adhesive 50 is thermally cured.

As mentioned above, the thermosetting material may be sintered silver. Sintered silver has extremely high thermal conductivity. Therefore, in this case, the thermal resistance between the optical semiconductor element 20 and the substrate 10A can be reduced. This allows heat from the optical semiconductor element 20 to be transferred to the substrate 10A more efficiently.

As mentioned above, the thermosetting material may be epoxy-containing sintered silver. When the second adhesive 50 contains epoxy-containing sintered silver, the adhesion between the second adhesive 50 and the optical semiconductor element 20 is enhanced. As a result, shrinkage of the second adhesive 50 during sintering is suppressed, making it difficult for the second adhesive 50 to peel off from the optical semiconductor element 20.

As in this embodiment, the first adhesive 40 and the second adhesive 50 may be separated from each other on the first surface 11 (or on the bottom surface 23b of the carrier 23). In this case, mixing of the first adhesive 40 and the second adhesive 50 before curing is avoided. This prevents the second adhesive 50 from interfering with the curing of the first adhesive 40.

As in this embodiment, the optical module 1A may further include a third adhesive 60 disposed between the first optical port 20a and the second optical port 30a. The third adhesive 60 may primarily contain a UV-curable material that has a faster curing rate (i.e., higher reactivity) than the UV-curable material of the first adhesive 40. In this case, the third adhesive 60 cures faster than the first adhesive 40 when irradiated with UV light. This allows the optical coupling between the first optical port 20a and the second optical port 30a to be more firmly maintained after optical axis adjustment. Note that if it is possible to selectively irradiate only the third adhesive 60 with UV light without irradiating the first adhesive 40 with UV light, the curing rate of the UV-curable material of the third adhesive 60 may be the same as that of the UV-curable material of the first adhesive 40.

As in this embodiment, the contact area between the second adhesive 50 and the optical semiconductor element 20 may be larger than the contact area between the first adhesive 40 and the optical semiconductor element 20. By making the contact area of the first adhesive 40 large enough to ensure sufficient fixing strength, and making the contact area of the second adhesive 50 larger than the contact area of the first adhesive 40, heat from the optical semiconductor element 20 can be transferred more efficiently to the substrate 10A. The fixing strength of the first adhesive 40 is, for example, at least sufficient to suppress optical axis misalignment between the first optical port 20a and the second optical port 30a when the second adhesive 50 is thermally cured.

In the manufacturing method of this embodiment, the optical semiconductor element 20 is fixed to the first surface 11 of the substrate 10A using a first adhesive 40 and a second adhesive 50. The first adhesive 40 primarily contains a UV-curable material. The second adhesive 50 has a higher thermal conductivity than the first adhesive 40 and primarily contains a thermosetting material. In the step of curing the first adhesive 40, the position of the optical semiconductor element 20 after optical axis adjustment is maintained using a chuck or the like, and ultraviolet light is irradiated to cure the first adhesive 40 while the second adhesive 50 is still in an uncured state. Thereafter, in the step of curing the second adhesive 50, the second adhesive 50 can be cured by heating while the position of the optical semiconductor element 20 after optical axis adjustment is maintained by the cured first adhesive 40. Therefore, according to the manufacturing method of this embodiment, the optical semiconductor element 20 can be fixed to the substrate 10A using a thermosetting material with high heat dissipation properties while maintaining the position of the optical semiconductor element 20 after optical axis adjustment. As a result, the heat from the optical semiconductor element 20 can be efficiently transferred to the substrate 10A while preventing misalignment of the optical axis between the first optical port 20a and the second optical port 30a.
[First Modification]

Figure 4 is a cross-sectional view of an optical module 1B according to a first modified example of the embodiment. The optical module 1B of this modified example differs from the optical module 1A of the embodiment in the following respects, but is identical to the optical module 1A of the embodiment in other respects. The optical module 1B of this modified example does not include the third adhesive 60. In addition, the optical module 1B of this modified example includes a substrate 10B instead of the substrate 10A. Figure 5 is a plan view showing the substrate 10B, the first adhesive 40, and the second adhesive 50. Note that while the optical module 1B of this modified example does not include the third adhesive 60, the third adhesive 60 may be provided in the same manner as the optical module 1A. For example, the third adhesive 60 may be provided for refractive index matching between the first optical port 20a and the second optical port 30a. The third adhesive 60 has a refractive index closer to the refractive index of the optical semiconductor chip 22 and the optical circuit element 30 than that of air (refractive index matching). This suppresses reflection between the first optical port 20a and the second optical port 30a. In optical modules 1A and 1B, the optical semiconductor element 20 is fixed to the substrates 10A and 10B mainly by a first adhesive 40 and a second adhesive 50.

As shown in Figures 4 and 5, the first adhesive 40 in this modified example is provided on two areas of the first surface 11 that sandwich the second adhesive 50. In other words, the area where the first adhesive 40 is provided, the second adhesive 50, and another area where the first adhesive 40 is provided are arranged side by side in this order. The arrangement direction may coincide with the arrangement direction (X direction) of the optical semiconductor element 20 and the optical circuit element 30. Furthermore, on the bottom surface 23b of the carrier 23, the first contact surface 23ba with which the first adhesive 40 comes into contact, the second contact surface 23bb with which the second adhesive 50 comes into contact, and another first contact surface 23ba with which the first adhesive 40 comes into contact are arranged side by side in this order.

The substrate 10B also has a first surface 11 and a groove 12 (recess) formed in the first surface 11. The groove 12 is formed at least between the first adhesive 40 and the second adhesive 50 when viewed from the normal direction (Z direction) of the first surface 11. As shown in FIG. 4, in a cross section extending in the X and Z directions, the shape of the groove 12 can be various shapes, such as a rectangle, an inverted trapezoid, or a semicircle. In one example, the width (length in the X direction) of the groove 12 is 0.1 mm, and the depth (length in the Z direction) of the groove 12 is 0.12 mm. The groove 12 may also be formed on the opposite side of the second adhesive 50 from the first adhesive 40 and on the opposite side of the first adhesive 40 from the second adhesive 50. In the example shown in FIG. 5, the groove 12 includes portions 12a, 12b, and 12c. Portion 12a surrounds one region 11a where the first adhesive 40 is provided. Portion 12b surrounds another region 11b where the first adhesive 40 is provided. Portion 12c surrounds region 11c where the second adhesive 50 is provided. The shapes of portions 12a and 12b when viewed from the normal direction (Z direction) of first surface 11 are, for example, square or rectangular. The shape of portion 12c when viewed from the normal direction (Z direction) of first surface 11 may also be square or rectangular. Alternatively, the shape of portion 12c when viewed from the normal direction (Z direction) of first surface 11 may be a square or rectangular shape with portions 12a and 12b embedded in the square or rectangular shape, as shown in FIG. 5 . In this case, the region where second adhesive 50 is provided has an H-shape. Note that in FIG. 5 , portions 12a and 12b are aligned in the X direction with region 11c sandwiched between them, but they may also be aligned in the Y direction with region 11c sandwiched between them.

Figures 6, 7, and 8 are cross-sectional views showing the second step ST2 (see Figure 3) in the manufacturing process of the optical module 1B. First, the optical semiconductor element 20, held by a chuck or the like, is brought close to the first adhesive 40 and the second adhesive 50 arranged on the first surface 11 (Figure 6). At this time, the first adhesive 40 and the second adhesive 50 are applied thickly in advance to account for variations in the height from the bottom surface 23b of the optical semiconductor element 20 to the first optical port 20a due to manufacturing errors. Next, the optical semiconductor element 20 (specifically, the bottom surface 23b of the carrier 23) is brought into contact with the first adhesive 40 and the second adhesive 50 (Figure 7). Next, the position and angle of the optical semiconductor element 20 are adjusted so that the first optical port 20a is optically coupled to the second optical port 30a (Figure 8). In this case, the height position of the first optical port 20a is determined by the height position of the second optical port 30a, so variations in the height from the bottom surface 23b of the optical semiconductor element 20 to the first optical port 20a are absorbed by deformation of the first adhesive 40 and the second adhesive 50 (changes in thickness in the Z direction). If the height from the bottom surface 23b to the first optical port 20a is large, the first adhesive 40 and the second adhesive 50 are compressed by the optical semiconductor element 20, reducing the thickness of the first adhesive 40 and the second adhesive 50. In this case, the excess first adhesive 40 and the second adhesive 50 spread in the X direction and approach each other. Note that the excess first adhesive 40 and the second adhesive 50 also spread in the Y direction.

In this modification, the substrate 10B has a groove 12 formed between the first adhesive 40 and the second adhesive 50, allowing excess first adhesive 40 and second adhesive 50 that spread toward each other to fall into the groove 12. This prevents the first adhesive 40 and the second adhesive 50 from mixing on the first surface 11 before curing. As a result, the second adhesive 50 is prevented from interfering with the curing of the first adhesive 40 on the first surface 11. For example, if uncured sintered silver mixes with uncured UV-curable resin, the UV-curable resin may not cure sufficiently. In this case, the first adhesive 40 and the second adhesive 50 mix within the groove 12. However, even if the first adhesive 40 in the groove 12 is not cured sufficiently, the impact on the fixation strength between the substrate 10B and the carrier 23 and the impact on heat dissipation through the second adhesive 50 are minimal.

In addition, in this modified example, the first adhesive 40 is provided on multiple regions 11a, 11b on the first surface 11 that sandwich the second adhesive 50. In this case, when the second adhesive 50 is cured by heating, tilting of the optical semiconductor element 20 with respect to the first surface 11 is suppressed, and the position of the first optical port 20a can be more stably maintained after optical axis adjustment. As a result, optical axis misalignment between the first optical port 20a and the second optical port 30a can be more reliably prevented.

Also, as shown in FIG. 5, the arrangement of regions 11a and 11b may be symmetrical with respect to axis C1 along the first surface 11. In this case, tilting of the optical semiconductor element 20 after the first adhesive 40 hardens can be prevented, and the position of the first optical port 20a can be maintained more stably after optical axis adjustment. Axis C1 may be the center line of region 11c in the X direction.

Furthermore, as in this modification, the region 11a where the first adhesive 40 is provided may be surrounded by the portion 12a of the groove 12, and the region 11b where the first adhesive 40 is provided may be surrounded by the portion 12b of the groove 12. In this case, surface tension is generated in the first adhesive 40 by the edge portions of the groove 12, so that the thickness of the first adhesive 40, which has low thixotropy, can be increased before it comes into contact with the optical semiconductor element 20. As a result, the width over which variations due to manufacturing errors in the height from the bottom surface 23b of the optical semiconductor element 20 to the first optical port 20a can be absorbed (the range over which the thickness of the first adhesive 40 can be changed) can be increased.
[Second Modification]

Figure 9 is a plan view showing a substrate 10C, a first adhesive 40, and a second adhesive 50 according to a second modified example. In this example, four regions 11d, 11e, 11f, and 11g in which the first adhesive 40 is provided are arranged at the four corners of region 11h in which the second adhesive 50 is provided. The substrate 10C has a groove 13 (recess). Groove 13 includes portions 13a, 13b, 13c, 13d, and 13e. Each of portions 13a to 13d surrounds each of the four regions 11d to 11g in which the first adhesive 40 is provided. Portion 13e surrounds region 11h in which the second adhesive 50 is provided. When viewed from the normal direction (Z direction) of the first surface 11, portions 13a to 13d each have a shape that is, for example, a square or a rectangle. The shape of portion 13e when viewed from the normal direction (Z direction) of first surface 11 may be square or rectangular. Alternatively, the shape of portion 13e when viewed from the normal direction (Z direction) of first surface 11 may be a square or rectangular shape with portions of portions 13a to 13d embedded in it, as shown in FIG. 9. In this case, region 11h where second adhesive 50 is provided has a cross shape, for example.

In the example shown in Figure 9, the substrate 10C also has a groove 13 formed between the first adhesive 40 and the second adhesive 50, so that the first adhesive 40 and the second adhesive 50 that spread toward each other during optical axis adjustment can be dropped into the groove 13. This prevents the uncured first adhesive 40 and the uncured second adhesive 50 from mixing on the first surface 11. As a result, it is possible to prevent the curing of the first adhesive 40 on the first surface 11 from being hindered by the second adhesive 50 being mixed in.

Also, in the example shown in Figure 9, the first adhesive 40 is provided on multiple areas 11d, 11e, 11f, and 11g of the first surface 11 that sandwich the second adhesive 50. In this case, when the second adhesive 50 is cured by heating, the optical semiconductor element 20 is fixed to the first surface 11 by the first adhesive 40 that has cured first, which prevents the optical semiconductor element 20 from tilting and more stably maintains the position of the first optical port 20a after optical axis adjustment. As a result, optical axis misalignment between the first optical port 20a and the second optical port 30a can be more reliably prevented.

Also, in the example shown in Figure 9, the arrangement of regions 11d to 11g is line-symmetrical with respect to axes C2 and C3 along the first surface 11. In this case, tilting of the optical semiconductor element 20 after the first adhesive 40 hardens can be prevented, and the position of the first optical port 20a can be maintained more stably after optical axis adjustment. Axis C2 may be the center line of region 11h in the X direction, and axis C3 may be the center line of region 11h in the Y direction.

9 , regions 11d to 11g, where first adhesive 40 is provided, may be surrounded by portions 13a to 13d of groove 13, respectively. In this case, surface tension is generated in first adhesive 40 by the edges of groove 13, so the thickness of first adhesive 40, which has low thixotropy, can be increased before it comes into contact with optical semiconductor element 20. As a result, the width over which variations due to manufacturing errors in the height from bottom surface 23b of optical semiconductor element 20 to first optical port 20a can be absorbed (the range over which the thickness of first adhesive 40 can be changed) can be increased.
[Third Modification]

Figure 10 is a cross-sectional view of an optical module 1C according to a third modified example. The optical module 1C of this modified example differs from the optical module 1B of the first modified example in the following respects, but is identical to the optical module 1B of the first modified example in other respects. The optical module 1C of this modified example includes a carrier 23A instead of the carrier 23. Like the carrier 23 of the above embodiment, the carrier 23A has a roughly rectangular parallelepiped appearance and has a mounting surface 23a and a bottom surface 23b. The optical semiconductor chip 22 is mounted on the mounting surface 23a. The bottom surface 23b faces the first surface 11. The constituent material of the carrier 23A is the same as that of the carrier 23 of the above embodiment.

Figure 11 is a perspective view showing the appearance of carrier 23A. As shown in Figures 10 and 11, in carrier 23A, first contact surface 23ba and second contact surface 23bb are both flat surfaces, and the distance D2 between second contact surface 23bb and first surface 11 is smaller than the distance D1 between first contact surface 23ba and first surface 11. In other words, first contact surface 23ba is recessed relative to second contact surface 23bb in a direction toward mounting surface 23a. That is, with respect to an imaginary plane including second contact surface 23bb, first contact surface 23ba is located closer to mounting surface 23a. Therefore, a step 23e is formed between first contact surface 23ba and second contact surface 23bb. The surface of step 23e is either perpendicular to bottom surface 23b or inclined relative to bottom surface 23b. The difference between distance D2 and distance D1 (D2-D1), i.e., the height of step 23e, is, for example, 20 μm or more and 50 μm or less. Distance D1 is, for example, 20 μm or more and 70 μm or less.

One of the two first contact surfaces 23ba of carrier 23A extends along the Y direction while contacting the first adhesive 40 provided on region 11a (see Figure 5). The other of the two first contact surfaces 23ba extends along the Y direction while contacting the first adhesive 40 provided on region 11b (see Figure 5). Both ends of these first contact surfaces 23ba reach a pair of side surfaces of carrier 23A, namely, side surfaces 23j and 23k that intersect the Y direction and face opposite each other.

The position of the step 23e in the X direction may be determined based on its relative position with respect to the groove 12. That is, when viewed from the normal direction of the bottom surface 23b, the step 23e may be located on the groove 12 or may be located closer to the outside than the groove 12.

The effects achieved by this modification are now explained. Figure 12 is a diagram illustrating the problems associated with the optical modules according to the above-described embodiment and each modification. As described above, the first adhesive 40 and the second adhesive 50 are spaced apart on the first surface 11. Furthermore, in the first and second modifications, before the first adhesive 40 and the second adhesive 50 harden, the excess first adhesive 40 and the second adhesive 50 that spread toward each other are dropped into the groove 12. However, the relatively fluid unhardened first adhesive 40 may spread along the bottom surface 23b of the carrier 23. In this case, as shown in part A of Figure 12, the first adhesive 40 comes into contact with the second adhesive 50 on and near the bottom surface 23b. This may cause the first adhesive 40 and the second adhesive 50 to mix on the first surface 11, potentially preventing the second adhesive 50 from hardening the first adhesive 40 on the first surface 11. Furthermore, if the first adhesive 40 gets between the second adhesive 50 and the bottom surface 23b, the area of the second contact surface 23bb will be reduced, reducing heat dissipation.

To address the above issue, in this modified example, the distance D2 between the second contact surface 23bb and the first surface 11 on the bottom surface 23b of the carrier 23A is smaller than the distance D1 between the first contact surface 23ba and the first surface 11. In this case, as shown in FIG. 13 , even if the uncured first adhesive 40 spreads along the bottom surface 23b, the spread portion of the first adhesive 40 is blocked by the step 23e, preventing the first adhesive 40 from spreading toward the second contact surface 23bb. Therefore, this modified example prevents the first adhesive 40 and the second adhesive 50 from mixing on or near the bottom surface 23b and prevents the second adhesive 50 from interfering with the curing of the first adhesive 40 on or near the bottom surface 23b. Furthermore, by preventing the first adhesive 40 from penetrating between the second adhesive 50 and the bottom surface 23b and increasing the area of the second contact surface 23bb, heat dissipation is improved.

14 is a perspective view showing the appearance of carrier 23B as another embodiment of this modification. Carrier 23B differs from carrier 23A in that it has first contact surfaces 23ba at each of the four corners of bottom surface 23b. When used in the second modification shown in FIG. 9, carrier 23B can achieve the effects of this modification described above.
[Fourth Modification]

Figure 15 is a cross-sectional view of an optical module 1D according to a fourth modified example. The optical module 1D of this modified example differs from the optical module 1C of the third modified example in the following respects, but is identical to the optical module 1C of the third modified example in other respects. The optical module 1D of this modified example includes a carrier 23C instead of the carrier 23A. Like the carrier 23 of the above embodiment, the carrier 23C has a roughly rectangular parallelepiped appearance and includes a mounting surface 23a and a bottom surface 23b. The optical semiconductor chip 22 is mounted on the mounting surface 23a. The bottom surface 23b faces the first surface 11. The constituent material of the carrier 23C is the same as that of the carrier 23 of the above embodiment.

Figure 16 is a perspective view showing the appearance of carrier 23C. As shown in Figures 15 and 16, the bottom surface 23b of carrier 23C includes, in addition to the first contact surface 23ba and the second contact surface 23bb, a third contact surface 23bc with which the first adhesive 40 comes into contact. When viewed from the normal direction of the bottom surface 23b, the first contact surface 23ba is located between the second contact surface 23bb and the third contact surface 23bc. In other words, the third contact surface 23bc is located outward of the first contact surface 23ba and on the opposite side of the first contact surface 23ba from the second contact surface 23bb. The third contact surface 23bc is a flat surface, like the first contact surface 23ba and the second contact surface 23bb. The distance D3 between the third contact surface 23bc and the first surface 11 is smaller than the distance D1 between the first contact surface 23ba and the first surface 11. In other words, the third contact surface 23bc protrudes toward the first surface 11 relative to the first contact surface 23ba. That is, the third contact surface 23bc is located closer to the first surface 11 than an imaginary plane including the first contact surface 23ba. Therefore, the first contact surface 23ba forms the bottom surface of a groove sandwiched between the second contact surface 23bb and the third contact surface 23bc. The side surfaces of the groove are perpendicular to the bottom surface 23b or inclined relative to the bottom surface 23b. The shape of the groove in a cross section perpendicular to the extension direction of the first contact surface 23ba is, for example, rectangular. The cross-sectional shape of the groove is not limited to this, and various shapes such as trapezoidal or semicircular can be used. The width W of the groove in a direction perpendicular to the extension direction is, for example, 50 μm or more and 140 μm or less. The depth of the groove, i.e., the difference between distance D2 and distance D1 (D2 - D1), is, for example, 50 μm or more and 100 μm or less.

The first adhesive 40 enters the groove and contacts the inner surface of the groove. As shown in FIG. 16, the groove and first contact surface 23ba extend linearly along the Y direction. This makes it easy to form the groove using, for example, a dicing blade. Both ends of the groove and first contact surface 23ba reach side surfaces 23j and 23k of the carrier 23A. Note that distance D3 may be greater than, less than, or equal to distance D2 between second contact surface 23bb and first surface 11.

In this modified example, the distance D2 between the second contact surface 23bb and the first surface 11 is also smaller than the distance D1 between the first contact surface 23ba and the first surface 11. Therefore, as shown in FIG. 17, the first adhesive 40 is prevented from spreading onto the second contact surface 23bb. This prevents the first adhesive 40 and the second adhesive 50 from mixing on or near the bottom surface 23b, and prevents the second adhesive 50 from interfering with the hardening of the first adhesive 40 on or near the bottom surface 23b.

In addition, as shown in FIG. 17, when the hardened first adhesive 40 reaches the side surface of the carrier 23C, a portion 41 of the first adhesive 40 located on the side surface of the carrier 23C and a portion 42 of the first adhesive 40 located on the first contact surface 23ba (i.e., inside the groove) sandwich a portion of the carrier 23C, i.e., a portion 231 of the carrier 23C including the third contact surface 23bc, from both sides. This increases the fixing strength between the carrier 23C and the substrate 10B.

FIG. 18 is a perspective view showing the appearance of carrier 23D as another embodiment of this modified example. Carrier 23D differs from carrier 23C in that both ends of the groove, which has first contact surface 23ba as its bottom, do not reach both side surface 23j and side surface 23k. In other words, there is a gap between first contact surface 23ba and side surface 23j and side surface 23k. Even with this embodiment, the above-described effects of this modified example can be achieved. However, since the embodiment shown in FIG. 18 does not allow for the groove to be formed using a dicing blade, the groove must be formed by sandblasting or the like.
[Fifth Modification]

Figure 19 is a cross-sectional view of an optical module 1E according to the fifth modified example. The optical module 1E of this modified example differs from the optical module 1C of the third modified example in the following respects, but is identical to the optical module 1C of the third modified example in other respects. The optical module 1E of this modified example includes a carrier 23E instead of the carrier 23A. Like the carrier 23 of the above embodiment, the carrier 23E has a roughly rectangular parallelepiped appearance and has a mounting surface 23a and a bottom surface 23b. The optical semiconductor chip 22 is mounted on the mounting surface 23a. The bottom surface 23b faces the first surface 11. The constituent material of the carrier 23E is the same as that of the carrier 23 of the above embodiment.

As shown in FIG. 19, the bottom surface 23b of the carrier 23E includes, in addition to the first contact surface 23ba and the second contact surface 23bb, a third contact surface 23bd with which the first adhesive 40 comes into contact. When viewed from the normal direction of the bottom surface 23b, the first contact surface 23ba is located between the second contact surface 23bb and the third contact surface 23bd. In other words, the third contact surface 23bd is located outward of the first contact surface 23ba and on the opposite side of the first contact surface 23ba from the second contact surface 23bb. The third contact surface 23bd is a flat surface, like the first contact surface 23ba and the second contact surface 23bb. The distance D4 between the third contact surface 23bd and the first surface 11 is greater than the distance D1 between the first contact surface 23ba and the first surface 11. In other words, the third contact surface 23bd is recessed relative to the first contact surface 23ba in the direction toward the mounting surface 23a. That is, the third contact surface 23bd is located closer to the mounting surface 23a than an imaginary plane including the first contact surface 23ba. As a result, a step 23i is formed between the first contact surface 23ba and the third contact surface 23bd. The surface of the step 23i is either perpendicular to the bottom surface 23b or inclined relative to the bottom surface 23b. The difference between the distance D4 and the distance D1 (D4 - D1), i.e., the height of the step 23i, is, for example, 0.01 mm or more and 0.05 mm or less.

In this modification, the distance D2 between the second contact surface 23bb and the first surface 11 is also smaller than the distance D1 between the first contact surface 23ba and the first surface 11. Therefore, the first adhesive 40 is prevented from spreading toward the second contact surface 23bb. Additionally, in this modification, the distance D4 between the third contact surface 23bd and the first surface 11 is greater than the distance D1 between the first contact surface 23ba and the first surface 11. In this case, the first adhesive 40 is further blocked by the step 23i, more effectively preventing the first adhesive 40 from spreading toward the second contact surface 23bb. Therefore, this modification more effectively prevents the first adhesive 40 and the second adhesive 50 from mixing on or near the bottom surface 23b and the second adhesive 50 from interfering with the hardening of the first adhesive 40 on or near the bottom surface 23b. Furthermore, the first adhesive 40 is further prevented from getting between the second adhesive 50 and the bottom surface 23b, and the area of the second contact surface 23bb can be increased, further improving heat dissipation.

The optical module and optical module manufacturing method according to the present disclosure are not limited to the above-described embodiments and variations, and various other modifications are possible. For example, the arrangement of the first adhesive 40 and the second adhesive 50 is not limited to the above-described embodiments and variations. Furthermore, while the above-described embodiments and variations illustrate an optical semiconductor element 20 in which an optical semiconductor chip 22 is mounted on a carrier 23, the carrier 23 may be omitted and the optical semiconductor element 20 may be formed solely from the optical semiconductor chip 22. Furthermore, the optical semiconductor chip 22 is not limited to a semiconductor optical amplifier (SOA) and may be another optical semiconductor chip, such as a semiconductor laser. The optical circuit element 30 is not limited to a silicon photonics chip and may be another optical circuit element, such as an optical waveguide substrate.

Moreover, the third, fourth, and fifth modified examples illustrate cases in which a substrate 10B having grooves 12 is used. However, this example is not limiting, and the third, fourth, and fifth modified examples may also use the substrate 10A of the embodiment (see Figure 1).

1A, 1B, 1C, 1D, 1E... Optical modules 10A, 10B, 10C... Base material 11... First surface 11a, 11b, 11c, 11d, 11e, 11f, 11g, 11h... Regions 12, 13... Groove (recess)
12a, 12b, 12c, 13a, 13b, 13c, 13d, 13e...portion 20...optical semiconductor element 20a...first optical port 21...side surface 22...optical semiconductor chip 23, 23A, 23B, 23C, 23D, 23E...carrier 23a...mounting surface 23b...bottom surface 23ba...first contact surface 23bb...second contact surface 23bc, 23bd...third contact surface 23c...side surface 23e, 23i...step 23j, 23k...side surface 30...optical circuit element 30a... Second optical port 30b...monitoring optical port 31...main surface 32...side surfaces 33, 35, 36...optical waveguide 33a...reflecting end 34...built-in photodiode 40...first adhesive 41, 42, 231...portion 50...second adhesive 60...third adhesive A1, A2, A3, A4...arrows C1, C2...axis lines D1, D2, D3, D4...distance OH...distance ST1...first step ST2...second step ST3...third step ST4...fourth step ST5...fifth step W...width

Claims (16)

a substrate having a first surface;
an optical semiconductor element provided on a side surface thereof, the optical semiconductor element having a first optical port for allowing light to enter or exit or for allowing light to enter or exit;
an optical circuit element that has a second optical port on a side surface thereof for allowing light to enter or exit or for entering and exiting, and that faces the first optical port and is optically coupled to the first optical port, and that is arranged on the first surface alongside the optical semiconductor element;
a first adhesive that mainly contains a UV curable material, has a first thermal conductivity, and is disposed between the optical semiconductor element and the first surface to fix the optical semiconductor element to the first surface;
a second adhesive that mainly contains a thermosetting material, has a second thermal conductivity higher than the first thermal conductivity, is disposed between the optical semiconductor element and the first surface, and fixes the optical semiconductor element to the first surface; and
An optical module comprising: The optical semiconductor element is
an optical semiconductor chip having the first optical port;
a carrier on which the optical semiconductor chip is mounted and which is fixed to the first surface by the first adhesive and the second adhesive;
The optical module of claim 1 , comprising: An optical module as described in claim 1 or claim 2, wherein the UV-curable material is a UV-curable resin. An optical module as described in claim 1 or claim 2, wherein the thermosetting material is sintered silver. An optical module as described in claim 1 or claim 2, wherein the thermosetting material is epoxy-containing sintered silver. An optical module as described in claim 1 or claim 2, wherein the first adhesive and the second adhesive are spaced apart from each other on the first surface. An optical module as described in claim 1 or claim 2, wherein the base material has a recess formed between the first adhesive and the second adhesive when viewed from the normal direction of the first surface. The optical module described in claim 1 or claim 2 further comprises a third adhesive disposed between the first optical port and the second optical port, the third adhesive primarily containing a UV-curable material that has a faster curing rate than the UV-curable material of the first adhesive. An optical module as described in claim 1 or claim 2, wherein the contact area between the second adhesive and the optical semiconductor element is larger than the contact area between the first adhesive and the optical semiconductor element. An optical module as described in claim 1 or claim 2, wherein the first adhesive is provided on multiple areas of the first surface that sandwich the second adhesive. The optical module described in claim 10, wherein the arrangement of the multiple regions is symmetrical with respect to an axis along the first surface. the optical semiconductor element has a bottom surface facing the first surface,
3. The optical module according to claim 1, wherein the first adhesive and the second adhesive are spaced apart from each other on the bottom surface of the optical semiconductor element. the carrier has a bottom surface opposite the first surface,
the bottom surface includes a first contact surface that comes into contact with the first adhesive and a second contact surface that comes into contact with the second adhesive;
The optical module according to claim 2 , wherein the distance between the second contact surface and the first surface is smaller than the distance between the first contact surface and the first surface. the bottom surface further has a third contact surface with which the first adhesive comes into contact;
When viewed from a normal direction of the bottom surface, the first contact surface is located between the second contact surface and the third contact surface,
The optical module according to claim 13 , wherein a distance between the third contact surface and the first surface is smaller than a distance between the first contact surface and the first surface. the bottom surface further has a third contact surface with which the first adhesive comes into contact;
When viewed from a normal direction of the bottom surface, the first contact surface is located between the second contact surface and the third contact surface,
The optical module according to claim 13 , wherein the distance between the third contact surface and the first surface is greater than the distance between the first contact surface and the first surface. a step of disposing, on a first surface of a substrate, an optical circuit element having a second optical port on a side surface thereof for allowing light to enter, exit, or enter and exit, a first adhesive containing mainly a UV curable material and having a first thermal conductivity, and a second adhesive containing mainly a thermosetting material and having a second thermal conductivity higher than the first thermal conductivity;
an optical semiconductor element having a first optical port on a side surface thereof for light incidence, emission, or light ingress and egress, and positioning the optical semiconductor element so that the first optical port is optically coupled to the second optical port while contacting the optical semiconductor element with the first adhesive and the second adhesive;
curing the first adhesive by irradiating it with ultraviolet light while holding the optical semiconductor element in a position adjusted to allow the optical coupling;
curing the second adhesive by heating in a state where the first adhesive is cured;
A method for manufacturing an optical module, comprising: