JP2016162878A - Optical semiconductor device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long-life optical semiconductor device and a method of manufacturing the same.SOLUTION: An optical semiconductor device 1 comprises: a semiconductor laser 3; a carrier 2 having a first surface 4a on which the semiconductor laser 3 is mounted, and a second surface 4b opposed to one end surface of a waveguide 12 of the semiconductor laser 3; and an adhesive part provided between the end surface and the second surface 4b, and adhered to both the semiconductor laser 3 and the carrier 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical semiconductor device and a method for manufacturing the optical semiconductor device.

  As a light emitting element in optical communication, a direct modulation type semiconductor laser element is used. For example, Patent Document 1 discloses a direct modulation semiconductor laser element capable of high-speed operation by appropriately determining the electrode stripe width and the carrier concentration of the cladding layer.

Japanese Patent Laid-Open No. 5-29703

  For example, in the direct modulation type semiconductor laser device as described above, in order to obtain high output, a reflective film may be formed on an end surface including one light emitting surface. The vicinity of the end face on which the reflective film is formed tends to generate heat due to light absorption. As the temperature rises due to the heat generation, the material in the vicinity of the end face changes in quality, and when the absorption coefficient increases, the temperature in the vicinity of the end face further increases. As a result, in the semiconductor laser element, optical damage (COD: Catastrophic Optical Damage) such as melting of the end face may occur. When optical damage occurs in the semiconductor laser element, the lifetime is deteriorated.

  An object of the present invention is to provide an optical semiconductor device having a long lifetime and a method for manufacturing the same.

  An optical semiconductor device according to an embodiment of the present invention includes a semiconductor laser, a carrier having a first surface on which the semiconductor laser is mounted, a second surface facing one end surface of the waveguide of the semiconductor laser, an end surface, and a second surface. And an adhesive portion that is provided between the semiconductor laser and the carrier.

  An optical semiconductor device manufacturing method according to another aspect of the present invention includes an end face, a surface that is different from the end face, and a semiconductor laser having a reflective film provided on the end face, a first face that faces the surface, and Forming a first adhesive portion on the first surface of the carrier and forming a second adhesive portion on the second surface of the carrier in an optical semiconductor device comprising: a carrier having a second surface facing the end surface; And a step of bringing the semiconductor laser into contact with the carrier by bringing the surface of the semiconductor laser into contact with the first adhesive portion and bringing the reflective film into contact with the second adhesive portion.

  ADVANTAGE OF THE INVENTION According to this invention, the optical semiconductor device which has a long lifetime, and its manufacturing method can be provided.

FIG. 1A is a plan view showing a part of the optical semiconductor device according to the first embodiment, and FIG. 1B is a cross-sectional view taken along the line Ib-Ib in FIG. FIG. 1C is a cross-sectional view taken along line Ic-Ic in FIG. FIG. 2A is an enlarged view of a part of the reflection film 7 and its periphery in FIG. FIG.2 (b) is an enlarged view which shows another aspect of Fig.2 (a). 3A to 3C are cross-sectional views for explaining the method for manufacturing the optical semiconductor device according to the first embodiment. 4A to 4C are cross-sectional views for explaining the method for manufacturing the optical semiconductor device according to the first embodiment. FIG. 5A is a plan view showing a part of the optical semiconductor device according to the comparative example, and FIG. 5B is a cross-sectional view taken along the line Vb-Vb in FIG. FIG. 6A is a plan view showing a part of the optical semiconductor device according to the first modification of the first embodiment, and FIG. 6B is a view taken along the line VIb-VIb in FIG. It is sectional drawing. FIG. 7A is a plan view showing the optical semiconductor device according to the first modification, and FIG. 7B is a cross-sectional view taken along line VIIb-VIIb in FIG. FIG. 8 is a plan view showing an optical semiconductor device according to a comparative example. FIG. 9A is a plan view showing an optical semiconductor device according to a second modification of the first embodiment, and FIG. 9B is a cross-sectional view taken along line IXb-IXb in FIG. 9A. is there.

[Description of Embodiment of Present Invention]
First, the contents of the embodiments of the present invention will be listed and described. One embodiment of the present invention includes a semiconductor laser, a first surface on which the semiconductor laser is mounted, a carrier having a second surface facing one end surface of the waveguide of the semiconductor laser, and between the end surface and the second surface And an adhesive portion that is attached to both the semiconductor laser and the carrier.

  According to this optical semiconductor device, one end face of the waveguide of the semiconductor laser and the second face of the carrier are joined to each other via the adhesive portion. In this case, the heat generated by light absorption in the vicinity of the end face is not only transmitted from the semiconductor laser to the first surface of the carrier, but also transmitted from the end face of the semiconductor laser to the second surface of the carrier through the adhesive portion. This makes it difficult for the temperature near the end face of the semiconductor laser to rise, and the occurrence of optical damage or the like is suppressed. Therefore, an optical semiconductor device having a long life can be provided.

  In addition, a reflection film including first, second, and third insulating films stacked in order is provided on the end face, and the first insulating film is located on the bonding portion side, and the second insulating film The refractive index of the film is higher than the refractive indexes of the first and third insulating films, the thickness of the second insulating film is a / 4 times the wavelength of light oscillated from the semiconductor laser, and a is It may be an odd number of 1 or more. In this case, the light emitted from the waveguide to the second surface side of the carrier can be favorably reflected by the reflective film.

  The reflective film further includes fourth and fifth insulating films laminated in order from the third insulating film side, and the refractive index of the fourth insulating film is the first, third, and fifth insulating films. And the thickness of the fourth insulating film is b / 4 times the wavelength of the light oscillated from the semiconductor laser, and b is a number different from a and an odd number of 1 or more. Also good. In this case, the light emitted from the waveguide to the second surface side of the carrier can be reflected more favorably by the reflective film.

  The carrier may include at least one of aluminum oxide, copper tungsten, aluminum nitride, silicon, and silicon carbide. In this case, since the carrier includes a material having high thermal conductivity, heat generated by the semiconductor laser can be transmitted to the carrier satisfactorily.

  The optical semiconductor device further includes a heat sink provided independently of the carrier and an integrated circuit mounted on the heat sink, and the carrier includes a second surface and a top surface intersecting the second surface. A transmission line substrate may be provided on the top surface of the protrusion, and the semiconductor laser may be electrically connected to the integrated circuit via the transmission line substrate and a wire. In this case, the length of the wire for electrically connecting the semiconductor laser and the integrated circuit to each other can be shortened by the transmission line substrate provided on the carrier. Thereby, the signal loss etc. by a wire can be suppressed, without changing the size of an optical semiconductor device.

  Further, the distance from one end of the transmission line substrate on the integrated circuit side to the integrated circuit may be closer than the distance from the side surface of the carrier on the integrated circuit side to the integrated circuit. In this case, the length of the wire can be further shortened, and signal loss due to the wire can be further suppressed.

  Another embodiment of the present invention is a semiconductor laser having an end surface, a surface different from the end surface, and a reflective film provided on the end surface, a first surface facing the surface, and a second surface facing the end surface. And forming a first adhesive portion on the first surface of the carrier and forming a second adhesive portion on the second surface of the carrier, and a surface of the semiconductor laser. And a step of bringing the reflective film into contact with the second adhesive portion and bringing the semiconductor laser into contact with the carrier.

  According to this method of manufacturing an optical semiconductor device, the semiconductor laser is bonded to the carrier by bringing the surface of the semiconductor laser into contact with the first adhesive portion and bringing the reflective film into contact with the second adhesive portion. In this case, the heat generated by light absorption in the vicinity of the end face is not only transmitted from the surface of the semiconductor laser to the first surface of the carrier via the first adhesive portion, but also from the end face of the semiconductor laser to the reflective film and the second film. It transmits to the 2nd surface of a carrier via an adhesion part. This makes it difficult for the temperature near the end face of the semiconductor laser to rise, and the occurrence of optical damage or the like is suppressed. Therefore, according to the manufacturing method, an optical semiconductor device having a long lifetime can be provided.

[Details of the embodiment of the present invention]
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals are used for the same elements or elements having the same functions, and redundant description is omitted.

(First embodiment)
FIG. 1A is a plan view showing a part of the optical semiconductor device according to the first embodiment. FIG. 1B is a cross-sectional view taken along line Ib-Ib in FIG. FIG. 1C is a cross-sectional view taken along line Ic-Ic in FIG. As shown in FIGS. 1A to 1C, the optical semiconductor device 1 includes a semiconductor laser 3 mounted on a carrier 2. Hereinafter, a predetermined direction in FIG. 1A is defined as a direction D1, a direction intersecting the predetermined direction in FIG. 1A is defined as a direction D2, and a thickness direction of the carrier 2 is defined as a direction D3. In the present embodiment, the direction D1 and the direction D2 are orthogonal to each other, and the direction D1 (or the direction D2) and the direction D3 are orthogonal to each other.

  The carrier 2 is a member made of a material having high thermal conductivity. The carrier 2 includes, for example, at least one of aluminum oxide (AlOx), copper tungsten (CuW), aluminum nitride (AlN), silicon (Si), and silicon carbide (SiN). The carrier 2 according to the present embodiment is made of CuW and has conductivity.

  The carrier 2 is a member in which a step 4 is provided on a part of a substantially rectangular base material. The step 4 is formed, for example, by removing a part of the carrier 2, and extends along the first surface 4a extending along the direction (direction D1 and direction D2) intersecting the direction D3, and along the direction D3. And has a second surface 4b extending. In the present embodiment, the first surface 4a and the second surface 4b are perpendicular or substantially perpendicular to each other. A first adhesive portion 5 is provided on the first surface 4a. The first bonding portion 5 is for bonding the carrier 2 and the semiconductor laser 3 to each other, and is, for example, solder made of alloy such as AuSn, SnIn, SnBi, or InAgSb having conductivity. Moreover, the 2nd adhesion part 6 is provided on the 2nd surface 4b. The second bonding portion 6 is for bonding the carrier 2 and the semiconductor laser 3 to each other. For example, a silver-containing epoxy resin (Ag-epoxy resin) having a melting point of about 120 ° C. and aluminum having a melting point of about 200 ° C. A mixture of contained epoxy resin (Al-epoxy resin) or the like is used.

  On the main surface side where the step 4 of the carrier 2 is provided, a protruding portion 41 having a second surface 4b and a top surface 41a intersecting with the second surface 4b is provided. The protruding portion 41 protrudes outward (upward) of the carrier 2 from the first surface 4a along the direction D3. In the present embodiment, the top surface 41a and the second surface 4b are perpendicular or substantially perpendicular to each other. As shown in FIG. 1B, the top surface 41a is located on the outer side of the carrier 2 with respect to the first surface 4a in the direction D3, and is provided side by side with the first surface 4a when viewed from the direction D3.

  The semiconductor laser 3 is a direct modulation type laser element mounted on the step 4. As shown in FIG. 1A, the semiconductor laser 3 has a quadrangular shape as viewed from the direction D3. The length (element length) along the direction D1 of the semiconductor laser 3 is, for example, 200 μm to 500 μm, and the length (width) along the direction D2 is, for example, 200 μm to 500 μm. As shown in FIG. 1C, the semiconductor laser 3 has a pair of surfaces 3a and 3d along a waveguide 12 which will be described later, and a pair of end faces 3b and 3c each including a resonance end face of the waveguide 12. . The surface 3 a of the semiconductor laser 3 and the first surface 4 a of the carrier 2 are opposed to each other and are joined to each other via the first adhesive portion 5.

The pair of end faces 3b and 3c of the semiconductor laser 3 intersect with the direction D1. An insulating reflective film 7 is provided on one end surface 3b. The reflective film 7 is, for example, at least two or more of a layer made of titanium oxide (TiO ₂ ), a layer made of silicon oxide (SiOx), a layer made of aluminum oxide (AlOx), and a layer made of aluminum nitride (AlN). Including layers. The total thickness of the reflective film 7 is, for example, 750 nm to 1460 nm. For example, the reflective film 7 preferably has a thickness that satisfies the total reflection condition.

  FIG. 2A is an enlarged view of a part of the reflection film 7 and its periphery in FIG. As shown in FIG. 2A, the reflective film 7 is composed of, for example, a low refractive index film 7a, a high refractive index film 7b, and a low refractive index, which are sequentially stacked along the direction D1 from the end face 3b side of the semiconductor laser 3. A film 7c, a high refractive index film 7d, a low refractive index film 7e, a high refractive index film 7f, and a low refractive index film 7g are included. Each of the low refractive index film 7a, the high refractive index film 7b, the low refractive index film 7c, the high refractive index film 7d, the low refractive index film 7e, the high refractive index film 7f, and the low refractive index film 7g is an insulating film. The refractive indexes of the high refractive index film 7b, the high refractive index film 7d, and the high refractive index film 7f are the refractive indexes of the low refractive index film 7a, the low refractive index film 7c, the low refractive index film 7e, and the low refractive index film 7g. Higher than. The refractive indexes of the high refractive index film 7b, the high refractive index film 7d, and the high refractive index film 7f are 2.3 ± 0.2, for example, 2.20. The refractive indexes of the low refractive index film 7a, the low refractive index film 7c, the low refractive index film 7e, and the low refractive index film 7g are 1.5 ± 0.2, for example, 1.47. The low refractive index film 7 g of the reflective film 7 is in contact with the second adhesive portion 6. The thickness of the high refractive index film 7b, the high refractive index film 7d, and the high refractive index film 7f in contact with the low refractive index film 7g is an odd number that is a quarter of the wavelength of the light oscillated from the semiconductor laser 3. Is double. Thereby, the reflective film 7 can obtain a favorable reflectance. Further, the thickness of the high refractive index film 7f is different from the thicknesses of the high refractive index film 7b and the high refractive index film 7d. In other words, the thickness of the high refractive index film 7f is a / 4 times the wavelength of the light oscillated from the semiconductor laser 3, and the thickness of the high refractive index films 7d and 7d is the wavelength of the light oscillated from the semiconductor laser 3. B / 4 times, and a and b are odd numbers of 1 or more and different numbers. Specifically, the low refractive index film 7a, the low refractive index film 7c, and the low refractive index film 7e are, for example, silicon oxide films, and the thickness thereof is 270 nm ± 20 nm. The high refractive index film 7b and the high refractive index film 7d are, for example, titanium oxide films, and their thickness is 190 nm ± 20 nm. The high refractive index film 7f is, for example, a titanium oxide film, and has a thickness of 100 nm ± 20 nm. The low refractive index film 7g is a silicon oxide film, for example, and has a thickness of 30 nm ± 10 nm. The reflectance of the wavelength of light emitted from the semiconductor laser 3 in the reflective film 7 is 80% or more.

  FIG.2 (b) is an enlarged view which shows another aspect of Fig.2 (a). As shown in FIG. 2B, for example, the reflective film 7 on the end face 3b of the semiconductor laser 3 is sequentially laminated along the direction D1, and the low refractive index film 7e, the high refractive index film 7f, and the low refractive index film are stacked. Only the rate film 7g may be included. In this case, the low refractive index film 7g is located closest to the second adhesive portion 6 side in the reflective film 7. The low refractive index films 7e and 7g are, for example, silicon oxide films, and the thickness thereof is 270 nm ± 20 nm. The high refractive index film 7f is, for example, a titanium oxide film, and has a thickness of 100 nm ± 20 nm. The reflectance of the wavelength of light oscillated from the semiconductor laser 3 in such a reflective film 7 is 50% or more, and the reflective film 7 has sufficient light reflection performance.

  The refractive index of the second bonding portion 6 is, for example, 1.55 to 1.61 when the refractive index of air is 1. Moreover, the thickness of the 2nd adhesion part 6 is several micrometers, for example. When such a second bonding portion 6 is used, the light emitted from the end surface 3 b of the semiconductor laser 3 is less affected by the return light due to reflection on the carrier 2. Note that the thickness of the second adhesive portion 6 is different from the distance along the direction D1 between the reflective film 7 and the carrier 2 when the second adhesive portion 6 is not provided.

  Returning to FIG. 1, an antireflective film 8 is provided on the other end face 3 c of the semiconductor laser 3. The antireflective film 8 includes, for example, one or both of titanium oxide and aluminum oxide. Here, the reflectance of the non-reflective film 8 at the wavelength of light emitted from the semiconductor laser 3 is preferably less than 1%.

  The end surface 3b of the semiconductor laser 3 and the second surface 4b of the carrier 2 face each other, and a stacked body 9 is provided between the end surface 3b and the second surface 4b. The laminated body 9 is formed by the reflective film 7 and the second adhesive portion 6 described above. Therefore, the end surface 3 b of the semiconductor laser 3 and the second surface 4 b of the carrier 2 are joined to each other via the stacked body 9. Specifically, the reflective film 7 and the second surface 4 b are bonded to each other via the second adhesive portion 6. The laminated body 9 may include a film other than the second adhesive portion 6 and the reflective film 7.

  The semiconductor laser 3 includes a waveguide 12, electrodes 13 and 14, wirings 15 and 16, electrode pads 17 and 18, a semiconductor substrate 21, a first cladding layer 22, a buried layer 23, and an insulating film 24. The semiconductor substrate 21 is, for example, an n-type InP substrate, and the thickness thereof is, for example, 100 μm to 200 μm. The first cladding layer 22 is, for example, an n-type InP layer. The buried layer 23 is provided on the first cladding layer 22 and has, for example, a structure in which a p-type InP layer, an n-type InP layer, and a p-type InP layer are stacked in this order, or a single-layer structure made of a semi-insulating semiconductor. doing. The insulating film 24 is provided so as to cover the buried layer 23 and grooves 25 and 26 and a mesa structure 30 described later, and includes, for example, one or both of silicon oxide and silicon nitride.

  The semiconductor laser 3 has a pair of grooves 25 and 26 extending along the direction D1. The pair of grooves 25 and 26 are formed, for example, by removing a part of the first cladding layer 22 and a part of the buried layer 23. The surfaces of the pair of grooves 25 and 26 are covered with an insulating film 24 except for a part thereof. Specifically, an opening 24a is provided in a part of the insulating film 24 covering the bottom surface 25a of the groove 25, and a part of the semiconductor substrate 21 is exposed. The electrode 13 is provided so as to bury the opening 24a. The electrode 13 is connected to the semiconductor substrate 21 through the opening 24 a and is electrically connected to the waveguide 12 through the semiconductor substrate 21. The electrode 13 is, for example, an AuZn metal layer or an alloy layer containing these metals.

  The waveguide 12 is formed in a mesa structure 30 sandwiched between a pair of grooves 25 and 26. As shown in FIG. 1C, the waveguide 12 is a stripe-shaped active layer extending along the direction D1 that is the light emission direction. The mesa structure 30 includes a first cladding layer 31, a second cladding layer 32, a waveguide 12, a buried layer 33, and a diffraction grating 34. The first cladding layer 31 is the same n-type InP layer as the first cladding layer 22, and is provided between the waveguide 12 and the semiconductor substrate 21. The second cladding layer 32 is provided on the waveguide 12 and is, for example, a p-type InP layer. The buried layer 33 has the same structure as the buried layer 23. The diffraction grating 34 is provided in the first cladding layer 31 so as to overlap the waveguide 12 in the direction D3, and has a refractive index different from that of the first cladding layer 31. When the first cladding layer 31 is an n-type InP layer, the diffraction grating 34 includes, for example, InGaAsP.

  As shown in FIG. 1C, the waveguide 12 has a pair of resonance end faces 12a and 12b. The resonance end face 12 a is included in the end face 3 b of the semiconductor laser 3, and the resonance end face 12 b is included in the end face 3 c of the semiconductor laser 3. The waveguide 12 has a plurality of InGaAsP layers so as to have, for example, a multi quantum well (MQW) structure. Note that the surfaces 3 a and 3 d of the semiconductor laser 3 extend along the waveguide 12.

  As shown in FIG. 1B, an opening 24b is provided in a part of the insulating film 24 on the waveguide 12, and a part of the second cladding layer 32 is exposed. The electrode 14 is provided so as to embed the opening 24b. The electrode 14 supplies a current to the waveguide 12. The electrode 14 is, for example, a metal layer such as AuZn or an alloy layer containing these metals.

  The wiring 15 extends from the groove 25 toward the side opposite to the mesa structure 30. The wiring 15 is a metal layer made of, for example, gold (Au). One end of the wiring 15 is connected to the electrode 13 provided in the groove 25. The other end of the wiring 15 is connected to the electrode pad 17. For example, a wire having a reference potential is bonded to the surface of the electrode pad 17. The wiring 16 extends from the mesa structure 30 toward the groove 26 side. The wiring 16 is a metal layer made of, for example, gold (Au). A modulation signal and a bias current are supplied to the wiring 16. One end of the wiring 16 is located on the mesa structure 30 and is connected to the electrode 14. The other end of the wiring 16 is connected to the electrode pad 18. For example, a wire to which a modulation signal is supplied and a wire to which a bias current is supplied are bonded to the surface of the electrode pad 18.

  Next, a method for manufacturing the optical semiconductor device 1 according to the first embodiment will be described with reference to FIGS. FIGS. 3A to 3C and FIGS. 4A to 4C are cross-sectional views for explaining the method of manufacturing the optical semiconductor device according to the first embodiment.

  First, as shown in FIG. 3A, the carrier 2 is prepared. Separately, the above-described semiconductor laser 3 (see FIGS. 1A to 1C) is prepared. A reflective film 7 is provided on the end face 3 b of the semiconductor laser 3.

  Next, as shown in FIG. 3B, a step 4 having a first surface 4 a and a second surface 4 b is formed on the carrier 2 by removing a part of the carrier 2. For example, the step 4 is formed on the carrier 2 by a known method such as etching, polishing, or cutting. Simultaneously with the formation of the step 4, the carrier 2 is formed with a protrusion 41 having a second surface 4b and a top surface 41a intersecting the second surface 4b.

  Next, as shown in FIG. 3C, the first adhesive portion 5 is formed on the first surface 4a of the step 4 by, for example, a dropping method. Further, as shown in FIG. 4A, the second adhesive portion 6 is formed on the second surface 4b of the step 4 by, for example, a coating method or a dispenser method. At this time, the second adhesive portion 6 is formed at a temperature at which the first adhesive portion 5 and the second adhesive portion 6 are melted together. In addition, the formation order of the 1st adhesion part 5 and the 2nd adhesion part 6 is not specifically limited. Therefore, the second adhesive portion 6 may be formed after the first adhesive portion 5 is formed, or the first adhesive portion 5 may be formed after the second adhesive portion 6 is formed.

  Next, as shown in FIGS. 4B and 4C, the semiconductor laser 3 is mounted on the carrier 2. First, the surface 3a of the semiconductor laser 3 is opposed to the first surface 4a, and the end surface 3b is opposed to the second surface 4b. Then, the surface 3 a is brought into contact with the first adhesive portion 5, and the reflective film 7 is brought into contact with the second adhesive portion 6. Thereafter, the first bonding portion 5 and the second bonding portion 6 are fixed by cooling, and the semiconductor laser 3 is bonded to the carrier 2. Through the above steps, a part of the optical semiconductor device 1 having the semiconductor laser 3 mounted on the carrier 2 is formed.

  The effects obtained by the optical semiconductor device 1 according to the first embodiment formed by the manufacturing method described above will be described. FIG. 5A is a plan view showing a part of the optical semiconductor device according to the comparative example, and FIG. 5B is a cross-sectional view taken along the line Vb-Vb in FIG. As shown in FIGS. 5A and 5B, no step is formed on the carrier 102 in the optical semiconductor device 101. In the comparative example, the semiconductor laser 3 is bonded to the main surface 102 a of the carrier 102 via the first bonding portion 5. In this case, during driving of the semiconductor laser 3, heat is likely to be accumulated in the vicinity of the end face 3b where the reflective film 7 is formed, and optical damage may occur. Therefore, the lifetime of the optical semiconductor device 101 according to the comparative example may be deteriorated.

  On the other hand, according to the optical semiconductor device 1 manufactured by the manufacturing method according to the first embodiment, the surface 3 a of the semiconductor laser 3 and the first surface 4 a of the carrier 2 are interposed via the first bonding portion 5. They are joined together. In addition, the end surface 3b of the semiconductor laser 3 and the second surface 4b of the carrier 2 are bonded to each other via the stacked body 9 (the second adhesive portion 6 and the reflective film 7). In this case, the heat generated by light absorption in the vicinity of the end surface 3b is not only transmitted from the surface 3a of the semiconductor laser 3 to the first surface 4a of the carrier 2 through the first adhesive portion 5, but also from the semiconductor laser 3 It is transmitted from the end surface 3 b to the second surface 4 b of the carrier 2 through the stacked body 9. Thereby, the temperature in the vicinity of the end face 3b of the semiconductor laser 3 is unlikely to rise, and the occurrence of optical damage or the like is suppressed. Therefore, the optical semiconductor device 1 having a long life can be provided.

  In addition, since semiconductor lasers and the like in recent years have been downsized, the resonator length and the like of the semiconductor laser have been shortened. When the heat dissipation path of such a semiconductor laser is limited, the structure of the optical semiconductor device 1 according to the first embodiment can be suitably employed.

  Further, on the end surface 3b, a low refractive index film 7g (first insulating film), a high refractive index film 7f (second insulating film), and a low refractive index film 7e (third insulating film) are sequentially stacked. The low refractive index film 7g is located on the second adhesive portion 6 side, and the refractive index of the high refractive index film 7f is the same as that of the low refractive index film 7g and the low refractive index film 7e. The thickness of the high refractive index film 7f that is higher than the refractive index is a / 4 times the wavelength of light oscillated from the semiconductor laser 3, and a may be an odd number of 1 or more. In this case, the light emitted from the waveguide 12 to the second surface 4 b side of the carrier 2 can be favorably reflected by the reflective film 7.

  The reflective film 7 further includes a high refractive index film 7d (fourth insulating film) and a low refractive index film 7c (fifth insulating film), which are stacked in this order from the low refractive index film 7e side. The refractive index of the refractive index film 7d is higher than the refractive indices of the low refractive index films 7c, 7e, 7g, and the thickness of the high refractive index film 7d is b / 4 times the wavelength of the light oscillated from the semiconductor laser 3. , B may be different from a and an odd number of 1 or more. In this case, the light emitted from the waveguide 12 to the second surface 4 b side of the carrier 2 can be reflected more favorably by the reflective film 7.

  The carrier 2 may include at least one of aluminum oxide, copper tungsten, aluminum nitride, silicon, and silicon carbide. In this case, since the carrier 2 includes a material having high thermal conductivity, heat generated by the semiconductor laser 3 can be transmitted to the carrier 2 satisfactorily. In the case where the carrier 2 is an insulator, a conductive film made of metal or alloy may be formed between the carrier 2 and the first bonding portion 5. As a result, the first adhesive portion 5 is prevented from being peeled off from the carrier 2 and electrical conduction to the semiconductor laser 3 through the first adhesive portion 5 is improved.

(First modification)
FIG. 6A is a plan view showing a part of the optical semiconductor device according to the first modification of the first embodiment, and FIG. 6B is a view taken along the line VIb-VIb in FIG. It is sectional drawing. As shown in FIGS. 6A and 6B, a transmission line substrate 42 is provided on the top surface 41 a of the protrusion 41 in the carrier 2. The transmission line substrate 42 includes an insulating substrate 43 and conductive layers (microstrip lines) 44 to 46 provided on the insulating substrate 43. The insulating substrate 43 is a substrate made of, for example, silicon oxide (SiOx), silicon nitride (SiN), aluminum oxide, or the like. The conductive layers 44 to 46 include, for example, a metal or alloy including gold or the like. The conductive layer 44 is set to a reference potential, for example. For example, a bias current is supplied to the conductive layer 45, and a modulation current is supplied to the conductive layer 46, for example. The conductive layer 44 is connected to the electrode pad 17 through the wire W1. The conductive layer 45 is connected to the electrode pad 18 via a wire W2, and the conductive layer 46 is connected to the electrode pad 18 via a wire W3 shorter than the wire W2.

  FIG. 7A is a plan view showing the optical semiconductor device according to the first modification, and FIG. 7B is a cross-sectional view taken along line VIIb-VIIb in FIG. As shown in FIGS. 7A and 7B, the optical semiconductor device 1A includes a heat sink 51 on which an integrated circuit 52 is mounted in addition to the carrier 2 on which the semiconductor laser 3 is mounted. Three wirings 53 to 55 extend from the integrated circuit 52 toward the carrier 2. Since the integrated circuit 52 serves as a heating element, the carrier 2 and the heat sink 51 are provided independently (separated from each other).

  The integrated circuit 52 is a circuit that supplies a reference potential, a modulation current, a bias current, and the like. The wiring 53 is connected to the conductive layer 44 via the wire W4, and provides the reference potential from the integrated circuit 52 to the conductive layer 44. The wiring 54 is connected to the conductive layer 45 via the wire W <b> 5, and provides a bias current from the integrated circuit 52 to the conductive layer 44. The wiring 55 is connected to the conductive layer 46 via the wire W6, and provides the modulation current from the integrated circuit 52 to the conductive layer 44. Thus, the semiconductor laser 3 is connected to the integrated circuit 52 through the transmission line substrate 42 and the wires W1 to W6.

  FIG. 8 is a plan view showing an optical semiconductor device according to a comparative example. As shown in FIG. 8, the optical semiconductor device 101A is not provided with a transmission line substrate. In such an optical semiconductor device 101A, the electrode pad 17 is connected to the wiring 53 through the wire W11, and the electrode pad 18 is connected to the wiring 54 through the wire W12 and to the wiring 55 through the wire W13. Is done. In this case, since the carrier 2 and the heat sink 51 are arranged independently (separated) from each other, the wires W11 to W13 become longer, and signal loss or the like due to the wires W11 to W13 occurs.

  In contrast, in the optical semiconductor device 1A according to the first modification, the length of the wires W1 to W6 for electrically connecting the semiconductor laser 3 and the integrated circuit 52 to each other is set so that the transmission line substrate 42 is the carrier 2. Can be shortened by the amount provided. Thereby, the signal loss etc. by the wires W1-W6 can be suppressed without changing the size of the optical semiconductor device 1A. In addition, the optical semiconductor device 1A according to the first modification also has the same effect as the optical semiconductor device 1 according to the first embodiment.

(Second modification)
FIG. 9A is a plan view showing an optical semiconductor device according to a second modification of the first embodiment, and FIG. 9B is a cross-sectional view taken along line IXb-IXb in FIG. 9A. is there. As shown in FIGS. 9A and 9B, the transmission line substrate 42 </ b> A of the optical semiconductor device 1 </ b> B has an extending portion 47 that extends toward the integrated circuit 52. A distance L1 from the one end 42b on the integrated circuit 52 side to the integrated circuit 52 in the extension portion 47 is closer than a distance L2 from the side surface 2a on the integrated circuit 52 side to the integrated circuit 52 in the carrier 2. In other words, the extending portion 47 does not overlap the carrier 2 in the direction D3. In addition, a conductive layer 46 longer than the other conductive layers 44 and 45 is formed on the extending portion 47. By forming the conductive layer 46 on the extending portion 47 in this way, the length of the wire W6 can be further shortened, and signal loss due to the wire W6 can be further suppressed. In addition, also in the optical semiconductor device 1B according to the second modification, the same effect as the optical semiconductor device 1A according to the first modification is exhibited.

  The optical semiconductor device and the manufacturing method of the optical semiconductor device according to the present invention are not limited to the above-described embodiments and modifications, and various other modifications are possible. For example, the carrier in the above embodiment may have a parallelogram shape as viewed from the direction D3 or may have a quadrangular shape with rounded corners.

  DESCRIPTION OF SYMBOLS 1,1A, 1B ... Optical semiconductor device, 2 ... Carrier, 3 ... Semiconductor laser, 3a ... Surface, 3b, 3c ... End face, 4 ... Level difference, 4a ... First surface, 4b ... Second surface, 5 ... First adhesion Part 6 ... second adhesive part 7 ... reflective film 7a, 7c, 7e, 7g ... low refractive index film, 7b, 7d, 7f ... high refractive index film, 9 ... laminated body, 12 ... waveguide, 12a, 12b ... Resonant end face, 41 ... Projection, 41a ... Top surface, 42, 42A ... Transmission line substrate, 43 ... Insulating substrate, 44-46 ... Conductive layer, 47 ... Extension, 51 ... Heat sink, 52 ... Integrated circuit, D1-D3 ... direction, W1-W6 ... wire.

Claims (7)

A semiconductor laser;
A carrier having a first surface on which the semiconductor laser is mounted and a second surface facing one end surface of the waveguide of the semiconductor laser;
An adhesive portion provided between the end surface and the second surface and bonded to both the semiconductor laser and the carrier;
An optical semiconductor device comprising: The end face is provided with a reflective film including first, second and third insulating films stacked in order,
The first insulating film is located on the bonding portion side,
The refractive index of the second insulating film is higher than the refractive indexes of the first and third insulating films,
The thickness of the second insulating film is a / 4 times the wavelength of light oscillated from the semiconductor laser,
The optical semiconductor device according to claim 1, wherein a is an odd number of 1 or more. The reflective film further includes fourth and fifth insulating films stacked in order from the third insulating film side,
The refractive index of the fourth insulating film is higher than the refractive indexes of the first, third, and fifth insulating films,
The thickness of the fourth insulating film is b / 4 times the wavelength of light oscillated from the semiconductor laser,
The optical semiconductor device according to claim 2, wherein b is a number different from a and an odd number of 1 or more.   The optical semiconductor device according to claim 1, wherein the carrier includes at least one of aluminum oxide, copper tungsten, aluminum nitride, silicon, and silicon carbide. A heat sink provided independently of the carrier;
An integrated circuit mounted on the heat sink;
Further comprising
The carrier has a protrusion including a second surface and a top surface intersecting the second surface;
A transmission line substrate is provided on the top surface of the protrusion,
The optical semiconductor device according to claim 1, wherein the semiconductor laser is electrically connected to the integrated circuit via the transmission line substrate and a wire.   The optical semiconductor device according to claim 5, wherein a distance from one end of the transmission line substrate on the integrated circuit side to the integrated circuit is closer than a distance from a side surface of the carrier on the integrated circuit side to the integrated circuit. A semiconductor laser having an end face, a surface different from the end face, and a reflective film provided on the end face;
A carrier having a first surface facing the surface and a second surface facing the end surface;
In an optical semiconductor device comprising:
Forming a first adhesive portion on the first surface of the carrier and forming a second adhesive portion on the second surface of the carrier;
Bonding the semiconductor laser to the carrier by bringing the surface of the semiconductor laser into contact with the first adhesive portion and bringing the reflective film into contact with the second adhesive portion;
An optical semiconductor device manufacturing method comprising:

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