WO2023140224A1 - 半導体レーザ装置及び半導体レーザ素子の製造方法 - Google Patents

半導体レーザ装置及び半導体レーザ素子の製造方法 Download PDF

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WO2023140224A1
WO2023140224A1 PCT/JP2023/001051 JP2023001051W WO2023140224A1 WO 2023140224 A1 WO2023140224 A1 WO 2023140224A1 JP 2023001051 W JP2023001051 W JP 2023001051W WO 2023140224 A1 WO2023140224 A1 WO 2023140224A1
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Prior art keywords
semiconductor laser
pad electrode
layer
laser element
laser device
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English (en)
French (fr)
Japanese (ja)
Inventor
洋希 永井
康光 久納
篤志 山田
東吾 中谷
剛 荒木
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Nuvoton Technology Corp Japan
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Nuvoton Technology Corp Japan
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Priority to CN202380017963.XA priority Critical patent/CN118575377A/zh
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/022—Mountings; Housings
    • H01S5/0233—Mounting configuration of laser chips
    • H01S5/0234—Up-side down mountings, e.g. Flip-chip, epi-side down mountings or junction down mountings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/024—Arrangements for thermal management
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H01S5/22—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure

Definitions

  • the present disclosure relates to a semiconductor laser device including a semiconductor laser element and a method of manufacturing a semiconductor laser element used in the semiconductor laser device.
  • Semiconductor laser elements are used as light sources for products in various fields, regardless of whether they are in the consumer sector or the industrial sector.
  • semiconductor lasers are used as light sources for image display devices such as displays and projectors, light sources for automobile headlamps, and light sources for industrial equipment such as laser processing devices.
  • a semiconductor laser element that emits a laser beam of infrared light (for example, a wavelength of 915 nm) is used as a light source of a laser processing apparatus that performs laser processing such as welding, joining, or cutting.
  • Such a high-output semiconductor laser element has a very large operating current, and the amount of heat generated at the front end (light emitting end) from which the laser light is emitted is large, so COD (catastrophic optical damage) may occur at the front end. For this reason, in order to realize stable operation over a long period of time while maintaining a high output state of the semiconductor laser element, it is important to quickly release the heat generated at the front end to the outside and suppress the rise in the operating temperature at the front end.
  • Patent Documents 1 and 2 disclose techniques for further improving this type of semiconductor laser device.
  • the adhesive that joins the semiconductor laser element and the heat dissipation member extends from between the semiconductor laser element and the heat dissipation member to the front end face of the heat dissipation member immediately below the front end face of the semiconductor laser element.
  • the materials of the bonding layer connected to the front end portion of the semiconductor laser element and the bonding layer connected to the other portion are changed to increase the melting point of the bonding layer connected to the front end portion.
  • a portion of the bonding member interposed between the semiconductor laser element and the heat sink may be extended to the front end of the semiconductor laser element to form a fillet of the bonding member in order to release heat generated at the front end of the semiconductor laser element to the heat sink.
  • the fillet applies stress to the front end of the semiconductor laser element.
  • the long-term reliability of the semiconductor laser device may deteriorate.
  • the stress applied to the semiconductor laser element from the end portion of the fillet of the joining member increases.
  • the composition ratio of the bonding layer is changed between the front end portion and other portions of the semiconductor laser element, so the amount of residual strain differs between the front end portion and the other portions.
  • the stress applied to the semiconductor laser element is non-uniformly generated, and the long-term reliability of the semiconductor laser element may deteriorate.
  • An object of the present disclosure is to solve such problems, and to provide a semiconductor laser device and a method for manufacturing a semiconductor laser element that can suppress deterioration in long-term reliability even if a bonding member is connected to the front end of the semiconductor laser element.
  • one aspect of the semiconductor laser device includes a heat sink, and a semiconductor laser element that is bonded to the heat sink via a bonding member and provided with a pad electrode.
  • the semiconductor laser element is arranged so that the pad electrode faces the heat sink.
  • the front end surface of the pad electrode connected to the exposed surface and parallel to the cavity length direction of the semiconductor laser element is formed such that at least a portion of the front end surface of the pad electrode is recessed, and a gap is formed between the bonding member and the front end surface of the pad electrode.
  • one aspect of the method for manufacturing a semiconductor laser element according to the present disclosure is a method for manufacturing a semiconductor laser element that is bonded to a heat sink via a bonding member by junction-down mounting, and includes the steps of: forming a semiconductor laminated structure including an active layer; forming an electrode layer above the semiconductor laminated structure; and forming a pad electrode above the electrode layer.
  • the stress applied to the semiconductor laser element can be alleviated, so that deterioration of the long-term reliability of the semiconductor laser element can be suppressed.
  • FIG. 1 is a plan view of a semiconductor laser device according to Embodiment 1.
  • FIG. FIG. 2A is a cross-sectional view of the semiconductor laser device according to Embodiment 1 taken along line IIA-IIA in FIG.
  • FIG. 2B is a cross-sectional view of the semiconductor laser device according to Embodiment 1 taken along line IIB-IIB in FIG.
  • FIG. 2C is a cross-sectional view of the semiconductor laser device according to Embodiment 1 taken along line IIC-IIC in FIG.
  • FIG. 3 is a plan view of the semiconductor laser device according to Embodiment 1.
  • FIG. 4A is a cross-sectional view of the semiconductor laser device according to Embodiment 1 taken along line IVA-IVA of FIG. 3.
  • FIG. 4B is a cross-sectional view of the semiconductor laser device according to Embodiment 1 taken along line IVB-IVB of FIG. 3.
  • FIG. FIG. 4C is a cross-sectional view of the semiconductor laser device according to Embodiment 1 taken along line IVC-IVC in FIG.
  • FIG. 5 is an enlarged cross-sectional view of the semiconductor laser device according to the first embodiment.
  • 6A is a cross-sectional view showing a step of forming a semiconductor laminated structure on a substrate in the method of manufacturing the semiconductor laser device according to Embodiment 1.
  • FIG. 6B is a cross-sectional view showing a step of forming a window region in the semiconductor laminated structure in the method of manufacturing the semiconductor laser device according to Embodiment 1.
  • FIG. 6C is a cross-sectional view showing a step of forming an opening in the semiconductor laminated structure in the method of manufacturing the semiconductor laser device according to Embodiment 1.
  • FIG. 6D is a cross-sectional view showing a step of forming separation grooves in the semiconductor laminated structure in the method of manufacturing the semiconductor laser device according to Embodiment 1.
  • FIG. 6E is a cross-sectional view showing a step of forming an insulating film on the semiconductor laminated structure in the method of manufacturing the semiconductor laser device according to Embodiment 1.
  • FIG. 6F is a cross-sectional view showing a step of forming a p-side electrode layer and a pad electrode in the method of manufacturing the semiconductor laser device according to Embodiment 1.
  • FIG. 6G is a cross-sectional view showing a step of forming an n-side electrode layer in the method of manufacturing the semiconductor laser device according to Embodiment 1.
  • FIG. FIG. 7 is a diagram for explaining a step of forming a pad electrode in the manufacturing method of the semiconductor laser device according to the first embodiment.
  • FIG. 8 is an SEM image of the semiconductor laser device according to the first embodiment.
  • FIG. 9 is a cross-sectional view showing the configuration of a semiconductor laser device of a comparative example.
  • FIG. 10 is a cross-sectional view showing the configuration of the semiconductor laser device according to the first embodiment.
  • FIG. 11 is a diagram showing the relationship between the distance from the light emitting end surface to the end of the pad electrode and the COD breakdown current.
  • FIG. 12 is a cross-sectional view showing the configuration of a semiconductor laser device according to Modification 1 of Embodiment 1.
  • FIG. 13 is a cross-sectional view showing the configuration of a semiconductor laser device according to Modification 2 of Embodiment 1.
  • FIG. 14A and 14B are diagrams for explaining the warped state of the semiconductor laser element in the semiconductor laser device according to the first embodiment.
  • FIG. FIG. 15 is a diagram showing the relationship between the position of the semiconductor laser element in the cavity length direction and the amount of warpage.
  • FIG. 16 is a plan view of a semiconductor laser device according to Embodiment 2.
  • FIG. 17A is a cross-sectional view of the semiconductor laser device according to Embodiment 2 taken along line XVIIA-XVIIA of FIG. 16.
  • FIG. 17B is a cross-sectional view of the semiconductor laser device according to Embodiment 2 taken along line XVIIB-XVIIB of FIG. 16.
  • FIG. 17C is a cross-sectional view of the semiconductor laser device according to Embodiment 2 taken along line XVIIC-XVIIC of FIG. 16.
  • FIG. 18 is an enlarged cross-sectional view of the semiconductor laser device according to the second embodiment.
  • FIG. 19 is an enlarged cross-sectional view of a semiconductor laser device according to a modification of the second embodiment.
  • 20A is a cross-sectional view showing a step of forming a second p-side electrode layer in the method of manufacturing a semiconductor laser device according to Embodiment 2.
  • FIG. 20B is a cross-sectional view showing a step of forming an n-side electrode layer in the manufacturing method of the semiconductor laser device according to Embodiment 2.
  • FIG. FIG. 21 is a plan view of a semiconductor laser device according to Embodiment 3.
  • FIG. FIG. 22A is a diagram showing a part of a cross section of the semiconductor laser device according to the third embodiment taken along line XIIIA--XXIIA in FIG.
  • FIG. 22B is a diagram showing a part of a cross section of the semiconductor laser device according to the third embodiment taken along line XIIB--XXIIB in FIG.
  • FIG. 22C is a diagram showing a part of a cross section of the semiconductor laser device according to the third embodiment taken along line XIIIC--XXIIC of FIG. 23A is a cross-sectional view showing a step of forming a pad electrode, a second pad electrode and a second p-side electrode layer in the method of manufacturing a semiconductor laser device according to Embodiment 3.
  • FIG. 23B is a cross-sectional view showing a step of forming an n-side electrode layer in the method of manufacturing a semiconductor laser device according to Embodiment 3.
  • FIG. 24 is a plan view of a semiconductor laser device according to Modification 1 of Embodiment 3.
  • FIG. 25 is a plan view of a semiconductor laser device according to Modification 2 of Embodiment 3.
  • each figure is a schematic diagram and is not necessarily strictly illustrated. Therefore, the scales and the like are not always the same in each drawing. In each figure, the same reference numerals are assigned to substantially the same configurations, and duplicate descriptions are omitted or simplified.
  • the terms “above” and “below” do not refer to the upward direction (vertically upward) and downward (vertically downward) in absolute spatial recognition, but are used as terms defined by relative positional relationships based on the stacking order in the stacking structure. Also, the terms “above” and “below” apply not only when two components are spaced apart from each other with another component between them, but also when two components are placed in contact with each other.
  • FIG. 1 is a plan view of a semiconductor laser device 1 according to Embodiment 1.
  • FIG. 2A to 2C are cross-sectional views of the semiconductor laser device 1 according to Embodiment 1.
  • FIG. 2A, 2B, and 2C show cross sections taken along line IIA-IIA in FIG. 1, line IIB-IIB in FIG. 1, and line IIC-IIC in FIG. 1, respectively.
  • 2A shows a cross section of a portion corresponding to a current injection region, which is a region into which current is injected
  • FIG. 2B shows a cross section of a portion corresponding to a current non-injection region, which is a region into which no current is injected, at the front end of the semiconductor laser device 1.
  • the semiconductor laser element 1 has a front facet 1a and a rear facet 1b opposite to the front facet 1a.
  • the front facet 1a is a front facet (light emission facet) from which laser light is emitted
  • the rear facet 1b is a rear facet from which laser light is not emitted.
  • the semiconductor laser device 1 has an optical waveguide with a front facet 1a and a rear facet 1b as resonator reflection mirrors. Therefore, the front facet 1a and the rear facet 1b serve as resonator facets. In other words, in the semiconductor laser device 1, a resonator is formed by the front facet 1a and the rear facet 1b. Therefore, the rear facet 1b has a higher reflectance than the front facet 1a. As an example, the reflectance of the front facet 1a is 5%, and the reflectance of the rear facet 1b is 95%.
  • the cavity length of the semiconductor laser device 1 is the distance between the front facet 1a and the rear facet 1b.
  • the cavity length of the semiconductor laser device 1 is 2 mm or more, and may be 4 mm or more. Note that the cavity length of the semiconductor laser device 1 may be less than 2 mm. Moreover, the semiconductor laser element 1 has a shape elongated in the cavity length direction.
  • the semiconductor laser element 1 emits a laser beam with an optical output of about 10 W to several tens of W class from the front facet 1a.
  • the semiconductor laser element 1 emits infrared light having an optical output of 25 W and a peak wavelength in a wavelength band of 976 nm. Note that the peak wavelength of the laser light of the semiconductor laser element 1 is not limited to this.
  • the semiconductor laser device 1 has a substrate 10 and a semiconductor lamination structure 20 formed above the substrate 10 .
  • the semiconductor laser device 1 in the present embodiment is a compound semiconductor laser made of an AlGaInAs-based III-V group semiconductor material. Therefore, the semiconductor laminated structure 20 has a structure in which a plurality of semiconductor layers each made of a III-V group semiconductor material are laminated.
  • a first facet coating film 20a is formed on the front facet of the semiconductor laminated structure 20.
  • a second facet coating film 20 b is formed on the rear facet of the semiconductor laminated structure 20 .
  • the first facet coating film 20a and the second facet coating film 20b are reflective films made up of dielectric multilayer films.
  • the first facet coating film 20a is a multilayer film of Al2O3 and SiO2
  • the second facet coating film 20b is a multilayer film of Al2O3 , SiO2 and Ta2O5 .
  • the reflectance of the first facet coating film 20a is 5%
  • the reflectance of the second facet coating film 20b is 95%.
  • the front facet of the first facet coating film 20a is the front facet 1a of the semiconductor laser device 1
  • the rear facet of the second facet coating film 20b is the rear facet 1b of the semiconductor laser device 1.
  • separation grooves 20c are formed in the side portions of the semiconductor laminated structure 20.
  • the separation groove 20c is a groove used when singulating the semiconductor laser device 1, and extends in the cavity length direction when viewed from above. In the present embodiment, separation groove 20c is formed to be constricted.
  • the substrate 10 is a planar substrate whose main surface is uniformly flat.
  • the substrate 10 is a semiconductor substrate such as a GaAs substrate or an insulating substrate such as a sapphire substrate.
  • substrate 10 is an n-type GaAs substrate.
  • the semiconductor laminated structure 20 has an n-type semiconductor layer 21, an active layer 22, a p-type semiconductor layer 23, and a p-type contact layer 24 on one surface of the substrate 10 in this order. That is, an n-type semiconductor layer 21 is formed on the substrate 10, an active layer 22 is formed on the n-type semiconductor layer 21, a p-type semiconductor layer 23 is formed on the active layer 22, and a p-type contact layer 24 is formed on the p-type semiconductor layer 23.
  • the n-type semiconductor layer 21 is an example of a first conductivity type first semiconductor layer.
  • the n-type semiconductor layer 21 has an n-type buffer layer, an n-type first composition gradient layer, an n-type cladding layer, and an n-type second composition gradient layer, which are sequentially stacked on the substrate 10 .
  • the n-type buffer layer, the n-type first composition gradient layer, the n-type cladding layer, and the n-type second composition gradient layer are n-type semiconductor layers intentionally doped with impurities such as silicon (Si), and are composed of, for example, n-type GaAs layers or n-type AlGaAs layers.
  • the n-type semiconductor layer 21 may include an undoped semiconductor layer that is not intentionally doped with impurities.
  • the n-type buffer layer is an n-type GaAs layer made of n-GaAs with a thickness of 0.50 ⁇ m
  • the n-type cladding layer is an n-Al 0.32 Ga 0.32 layer with a thickness of 3.0 ⁇ m.
  • the active layer 22 is formed on the n-type semiconductor layer 21 .
  • the active layer 22 has an n-type guide layer, an n-side second barrier layer, an n-side first barrier layer, a well layer, a p-side first barrier layer, a p-side second barrier layer, and a p-type guide layer, which are sequentially laminated on the n-type semiconductor layer 21.
  • the n-type guide layer, the n-side second barrier layer, and the n-side first barrier layer are n-type semiconductor layers intentionally doped with impurities such as silicon, and are composed of, for example, an n-type AlGaAs layer or an n-type AlGaInAs layer.
  • the n-type guide layer is an n-type AlGaAs layer made of n-Al 0.285 Ga 0.715 As with a thickness of 1.05 ⁇ m
  • the n-side second barrier layer is an n-type AlGaAs layer made of n-Al 0.15 Ga 0.85 As with a thickness of 0.0268 ⁇ m and Al 0.15 Ga 0.85 As with a thickness of 0.0083 ⁇ m.
  • the first n-side barrier layer is an AlGaInAs layer of 0.0018 ⁇ m Al 0.50 Ga 0.32 In 0.18 As.
  • the p-side first barrier layer, the p-side second barrier layer, and the p-type guide layer are p-type semiconductor layers intentionally doped with impurities such as carbon (C), and are composed of, for example, p-type AlGaAs layers or p-type AlGaInAs layers. Note that the p-side first barrier layer and the p-side first barrier layer may have an undoped region not doped with impurities in addition to the doped regions doped with impurities.
  • the p-side first barrier layer is an AlGaInAs layer made of Al 0.50 Ga 0.32 In 0.18 As with a thickness of 0.0018 ⁇ m
  • the p-side second barrier layer is an undoped AlGaAs layer made of Al 0.15 Ga 0.85 As with a thickness of 0.0083 ⁇ m and p-Al 0.15 G with a thickness of 0.025 ⁇ m. and a p-type AlGaAs layer made of a 0.85 As.
  • the p-type guide layer is a p-type AlGaAs layer made of p-Al 0.28 Ga 0.72 As having a thickness of 0.22 ⁇ m.
  • the well layer is, for example, a single quantum well structure including a single quantum well layer.
  • the well layer is composed of, for example, an undoped InGaAs layer.
  • the well layer is an InGaAs layer made of In 0.135 Ga 0.865 As with a thickness of 0.0090 ⁇ m.
  • the well layer is not limited to a single quantum well structure, and may be a multiple quantum well structure including a plurality of quantum well layers.
  • the p-type semiconductor layer 23 is an example of a second semiconductor layer of a second conductivity type different from the first conductivity type.
  • the p-type semiconductor layer 23 has a p-type first compositionally graded layer, a p-type cladding layer and a p-type second compositionally graded layer, which are sequentially stacked on the active layer 22 .
  • the p-type first composition gradient layer, the p-type cladding layer, and the p-type second composition gradient layer are p-type semiconductor layers intentionally doped with impurities such as carbon, and are composed of, for example, p-type AlGaAs layers.
  • the impurity concentrations of the p-type first composition gradient layer, the p-type cladding layer and the p-type second composition gradient layer are, for example, less than 1.0 ⁇ 10 19 (cm ⁇ 3 ).
  • the p-type cladding layer is a p-type AlGaAs layer made of p-Al 0.70 Ga 0.30 As with a thickness of 0.75 ⁇ m
  • the p-type contact layer 24 is an example of a second conductivity type third semiconductor layer.
  • the p-type contact layer is a p-type semiconductor layer intentionally doped with an impurity such as carbon, and is composed of, for example, a p-type GaAs layer.
  • the impurity concentration of the p-type contact layer is, for example, 1.0 ⁇ 10 19 (cm ⁇ 3 ) or more.
  • the p-type contact layer is a p-type GaAs layer made of p-GaAs with a thickness of 0.25 ⁇ m.
  • the semiconductor laser device 1 has a ridge portion 1R formed in a ridge shape as a waveguide extending in the cavity length direction.
  • the ridge portion 1R extends in the resonator length direction.
  • the ridge portion 1 ⁇ /b>R functions as a current injection region in the semiconductor laser device 1 .
  • the ridge portion 1R is formed in the p-type semiconductor layer 23 and the p-type contact layer 24. As shown in FIGS.
  • the ridge portion 1R is formed by digging an opening 30 into the p-type semiconductor layer 23 and the p-type contact layer 24 .
  • the p-type contact layer 24 is the uppermost layer of the ridge portion 1R.
  • a bottom portion 30a of the opening portion 30 constitutes a ridge bottom portion and is a flat portion located within the p-type semiconductor layer 23 .
  • the opening 30 has a pair of lateral grooves 31 .
  • the ridge portion 1R is sandwiched between a pair of lateral groove portions 31 in the opening portion 30.
  • the pair of lateral grooves 31 of the opening 30 are parallel to each other and extend in the laser cavity length direction.
  • the opening 30 has not only the pair of lateral grooves 31 but also a front groove 32 and a rear groove 33 .
  • the front groove portion 32 is formed at the front end portion of the semiconductor laser element 1 on the extension of the ridge portion 1R
  • the rear groove portion 33 is formed at the rear end portion of the semiconductor laser element 1 on the extension of the ridge portion 1R.
  • the ridge portion 1R does not exist at the front end portion and the rear end portion of the semiconductor laser element 1.
  • FIG. A pair of lateral groove portion 31, front groove portion 32, and rear groove portion 33 are formed continuously. Therefore, the ridge portion 1R is configured to be surrounded by the opening portion 30. As shown in FIG. Note that the front groove portion 32 and the rear groove portion 33 may not be formed.
  • a pair of wings 40 are formed in the semiconductor laser element 1 by forming openings 30 in the p-type semiconductor layer 23 and the p-type contact layer 24 .
  • the pair of wing portions 40 are positioned on the sides of the ridge portion 1R. That is, the ridge portion 1R is sandwiched between the pair of wing portions 40 through the opening portion 30.
  • the pair of wing portions 40 extends along the resonator length direction of the semiconductor laser device 1 .
  • an insulating film 50 made of a dielectric film such as SiO 2 or SiN is formed on the p-type contact layer 24 except for a portion on the ridge portion 1R. Specifically, the insulating film 50 is formed to have an opening 50a on the ridge portion 1R of the p-type contact layer 24 .
  • the insulating film 50 functions as a current blocking film. Therefore, the opening 50a of the insulating film 50 is a current injection window through which current passes.
  • the insulating film 50 covers the bottom 30 a of the opening 30 formed in the p-type semiconductor layer 23 and the p-type contact layer 24 . Therefore, the bottom portion 30 a of the opening portion 30 (specifically, the bottom portion of the front groove portion 32 ) at the front end portion of the semiconductor laser element 1 is covered with the insulating film 50 . That is, the insulating film 50 covers the front end portion of the semiconductor laser element 1 when viewed from above. As a result, it is possible to suppress the current from spreading to the front end portion and the window region of the semiconductor laser device 1, thereby suppressing a decrease in optical output and a decrease in reliability.
  • the insulating film 50 also covers the side surfaces of the semiconductor laminated structure 20. As shown in FIGS. Specifically, the insulating film 50 covers the entire side surface of the p-type contact layer 24 , the entire side surface of the p-type semiconductor layer 23 , the entire side surface of the active layer 22 , and part of the side surface of the n-type semiconductor layer 21 .
  • the semiconductor laminated structure 20 in the semiconductor laser device 1 has a window region 22a (facet window structure) at the front end in the cavity length direction. Specifically, in the current non-injection region near the front facet of the ridge portion 1R in the active layer 22, a window region 22a is formed in a region having a predetermined length from the front facet 1a. The window region 22 a is formed at the front end portion of the semiconductor laminated structure 20 . A region of the waveguide where the window region 22a is not formed is a gain region.
  • window region 22a face window structure
  • the front end of the semiconductor laser device 1 can be made transparent and light absorption near the front facet 1a can be reduced. Thereby, generation of COD at the front end portion of the semiconductor laser element 1 can be suppressed.
  • a similar window region may be formed at the rear end portion of the semiconductor laminated structure 20 as well. It should be noted that window regions may not be formed at the front and rear ends of the semiconductor laser device 1 .
  • the semiconductor laser device 1 has a p-side electrode layer 61 as a p-side first electrode.
  • the p-side electrode layer 61 is formed on the semiconductor laminated structure 20 . Specifically, the p-side electrode layer 61 is formed above the p-type contact layer 24 . In the present embodiment, the p-side electrode layer 61 is formed in contact with the p-type contact layer 24 above the ridge portion 1R. Specifically, the p-side electrode layer 61 is in ohmic contact with the p-type contact layer 24 . In the present embodiment, the p-side electrode layer 61 is formed not only on the ridge portion 1R, but also inside the opening portion 30 and on the wing portions 40 with the insulating film 50 interposed therebetween.
  • the p-side electrode layer 61 is a metal layer made of a metal material.
  • the p-side electrode layer 61 is, for example, a single layer film or a multilayer film made of at least one of Pt, Ti, Cr, Ni, Mo and Au.
  • the p-side electrode layer 61 is composed of a multilayer film.
  • the p-side electrode layer 61 is a multilayer film having a three-layer structure in which a Ti film, a Pt film and an Au film are laminated in this order from the p-type contact layer 24 side.
  • the semiconductor laser device 1 also has an n-side electrode layer 62 as a second n-side electrode.
  • the n-side electrode layer 62 is formed below the other surface (lower surface) of the substrate 10 that is opposite to the one surface (surface on the semiconductor laminated structure 20 side). In this embodiment, the n-side electrode layer 62 is directly formed on the other surface of the substrate 10 .
  • the n-side electrode layer 62 is a metal layer made of a metal material.
  • the n-side electrode layer 62 is, for example, a single layer film or a multilayer film made of at least one of Cr, Ti, Ni, Pd, Pt, Au and Ge.
  • the n-side electrode layer 62 is composed of a multilayer film.
  • the n-side electrode layer 62 is a multi-layer film having a six-layer structure in which an AuGe film, a Ni film, an Au film, a Ti film, a Pt film, and an Au film are laminated in this order from the substrate 10 side.
  • the semiconductor laser device 1 has a pad electrode 70 .
  • Pad electrode 70 is formed above p-side electrode layer 61 .
  • the pad electrode 70 is laminated on the p-side electrode layer 61 so as to be in contact with the upper surface of the p-side electrode layer 61 . That is, the p-side electrode layer 61 is formed on the bottom surface of the pad electrode 70 .
  • the pad electrode 70 is a p-side pad electrode forming a p-side electrode together with the p-side electrode layer 61 .
  • pad electrode 70 is formed above p-side electrode layer 61 . Therefore, the pad electrode 70 is formed not only above the ridge portion 1R but also above the wing portion 40. As shown in FIG.
  • the pad electrode 70 is a metal layer made of a metal material.
  • the pad electrode 70 is an Au plating film, but is not limited to this.
  • the front end face of the pad electrode 70 is located at a position recessed from the front end face 1a of the semiconductor laser element 1.
  • the semiconductor laser element 1 has an exposed surface 61 a exposed from the pad electrode 70 .
  • this exposed surface 61 a is the surface of the p-side electrode layer 61 .
  • the distance L between the front end face of the pad electrode 70 and the front end face 1a of the semiconductor laser element 1 (the receding amount of the front end portion of the pad electrode 70) is, for example, 5 ⁇ m or more and 15 ⁇ m or less, but is not limited to this.
  • the front end face of the pad electrode 70 is formed so that at least a portion thereof is recessed. Specifically, an eaves portion 71 (overhang portion) is formed at the front end portion of the pad electrode 70 .
  • the front end surface of the pad electrode 70 is partially recessed because the eaves portion 71 is formed at the front end portion of the pad electrode 70 .
  • the front end surface of the pad electrode 70 is formed with a concave portion 70a in which a portion of the front end surface is recessed rearward in the resonator length direction.
  • the eaves portion 71 is also formed on the side surface of the pad electrode 70 .
  • the eaves portion 71 is also formed on the rear end surface of the pad electrode 70 . That is, the eaves portion 71 is formed over the entire circumference of the pad electrode 70 .
  • FIG. 3 is a plan view of the semiconductor laser device 100 according to Embodiment 1.
  • FIG. 4A to 4C are cross-sectional views of the semiconductor laser device 100 according to Embodiment 1.
  • FIG. 4A, 4B, and 4C show cross sections taken along line IVA-IVA of FIG. 3, line IVB-IVB of FIG. 3, and line IVC-IVC of FIG. 3, respectively.
  • 5 is an enlarged cross-sectional view of a region V surrounded by broken lines in FIG. 4C.
  • the semiconductor laser device 100 includes a semiconductor laser element 1, a heat sink 2, and a bonding member 3 for bonding the semiconductor laser element 1 and the heat sink 2 together. That is, the semiconductor laser element 1 is bonded to the heat sink 2 via the bonding member 3 .
  • the semiconductor laser element 1 is joined to the heat sink 2 by junction-down mounting. That is, the semiconductor laser element 1 is arranged so that the pad electrode 70 faces the heat sink 2 side. Specifically, the semiconductor laser element 1 is arranged above the heat sink 2 so that the pad electrode 70 side faces downward, and is joined to the heat sink 2 by the joining member 3 .
  • the heat sink 2 is a heat radiating member for radiating heat generated by the semiconductor laser element 1 .
  • the heat sink 2 also functions as a submount (base) for mounting the semiconductor laser element 1 .
  • a semiconductor laser element 1 is positioned on a heat sink 2 .
  • the heat sink 2 has a heat sink body 2a, a first conductor layer 2b, a second conductor layer 2c, a third conductor layer 2d, and a fourth conductor layer 2e.
  • the first conductor layer 2b and the second conductor layer 2c are formed on the semiconductor laser element 1 side of the heat sink main body 2a.
  • the first conductor layer 2b is formed on the upper surface of the heat sink main body 2a
  • the second conductor layer 2c is formed on the upper surface of the first conductor layer 2b.
  • the second conductor layer 2c also covers the front end surface and the rear end surface of the first conductor layer 2b so that the first conductor layer 2b is not exposed.
  • the third conductor layer 2d and the fourth conductor layer 2e are formed on the opposite side of the heat sink main body 2a from the semiconductor laser element 1 side.
  • the third conductor layer 2d is formed on the lower surface of the heat sink main body 2a
  • the fourth conductor layer 2e is formed on the lower surface of the third conductor layer 2d.
  • the fourth conductor layer 2e also covers the front and rear end surfaces of the third conductor layer 2d so that the third conductor layer 2d is not exposed.
  • the heat sink main body 2a is made of a high heat conductive material such as AlN, CuW, diamond, SiC, or the like.
  • the heat sink main body 2a is made of AlN.
  • the shape of the heat sink main body 2a is, for example, a rectangular parallelepiped.
  • the first conductor layer 2b, the second conductor layer 2c, the third conductor layer 2d, and the fourth conductor layer 2e are metal layers made of a metal material.
  • the first conductor layer 2b, the second conductor layer 2c, the third conductor layer 2d, and the fourth conductor layer 2e may be single layer films or multilayer films.
  • the first conductor layer 2b and the third conductor layer 2d which are in contact with the heat sink main body 2a, are high heat dissipation conductor layers made of a metal material with high conductivity such as Cu.
  • the first conductor layer 2b and the third conductor layer 2d are Cu films.
  • the second conductor layer 2c in contact with the joint member 3 is preferably made of a metal material having high adhesion to the joint member 3.
  • the second semiconductor layer 2c is a multilayer film having a three-layer structure in which a Ni film, an Au film and a Pt film are sequentially formed from the first semiconductor layer 2b toward the bonding member 3.
  • FIG. The fourth conductor layer 2e has the same configuration as the second conductor layer 2c.
  • the semiconductor laser element 1 mounted on the heat sink 2 is arranged so that the front end face 1a does not protrude from the front end face of the heat sink 2. As shown in FIG. That is, the front end face 1a of the semiconductor laser element 1 is located at a position recessed from the front end face of the heat sink 2. As shown in FIG. The front end surface 1a of the semiconductor laser element 1 is positioned between the front end surface of the heat sink main body 2a of the heat sink 2 and the front end surface of the second conductor layer 2c.
  • the joining member 3 joins the semiconductor laser element 1 and the heat sink 2 and is interposed between the semiconductor laser element 1 and the heat sink 2.
  • the joining member 3 extends to the front end portion of the semiconductor laser element 1 and is connected to the front end portion of the semiconductor laser element 1 .
  • the heat generated at the front end of the semiconductor laser element 1 can be conducted to the heat sink 2 via the bonding member 3, so that the occurrence of COD at the front end of the semiconductor laser element 1 can be suppressed.
  • the bonding member 3 is connected to the exposed surface 61 a at the front end of the semiconductor laser element 1 . That is, the bonding member 3 is connected to the p-side electrode layer 61 of the semiconductor laser element 1 .
  • a fillet 3 a is formed in the joining member 3 , and the fillet 3 a is connected to the front end portion of the semiconductor laser element 1 .
  • the fillet 3 a is a portion of the joint member 3 protruding from between the semiconductor laser element 1 and the heat sink 2 .
  • the fillet 3a is a solder fillet.
  • the bonding member 3 is connected to the exposed surface 61 a of the semiconductor laser element 1 up to the position of the front end surface of the semiconductor laminated structure 20 of the semiconductor laser element 1 . That is, the fillet 3 a is formed up to the position of the front end surface of the semiconductor laminated structure 20 . The fillet 3a may be formed up to the position of the front end surface 1a of the semiconductor laser element 1 on the exposed surface 61a.
  • the bonding member 3 is connected not only to the front end portion of the semiconductor laser element 1 but also to the front end surface of the heat sink 2 .
  • the fillet 3a of the bonding member 3 protruding forward from between the pad electrode 70 and the heat sink 2 is connected to the exposed surface 61a at the front end portion of the semiconductor laser element 1 and to the front end surface of the second conductor layer 2c of the heat sink 2.
  • the bonding member 3 in a longitudinal section perpendicular to the cavity length direction of the exposed surface 61a of the semiconductor laser element 1, the bonding member 3 is connected to the exposed surface 61a over at least the entire width of the ridge portion 1R (ridge width).
  • the bonding member 3 is formed on the entire exposed surface 61a of the semiconductor laser element 1 in a longitudinal section perpendicular to the cavity length direction.
  • the width of the joining member 3 is larger than the width of the exposed surface 61a.
  • the joining member 3 is, for example, a solder material such as AuSn solder containing AuSn as a main component, or a metal brazing material.
  • the joining member 3 is AuSn solder.
  • the thickness of the bonding member 3 between the semiconductor laser element 1 and the heat sink 2 is, for example, 3 ⁇ m to 7 ⁇ m.
  • a gap 4 is formed between the bonding member 3 and the front end surface of the pad electrode 70 in the longitudinal section parallel to the resonator length direction of the semiconductor laser element 1.
  • the gap 4 is a gap (cavity) surrounded by the fillet 3a of the bonding member 3, the front end surface of the pad electrode 70, and the exposed surface 61a of the semiconductor laser element 1, and is formed intentionally.
  • the gap 4 exists at least between the eaves portion 71 of the pad electrode 70 and the exposed surface 61 a of the semiconductor laser element 1 .
  • the cross-sectional shape of the gap 4 is, for example, substantially trapezoidal. Therefore, both the front end surface of the pad electrode 70 in the gap 4 and the inner surface of the joint member 3 (fillet 3a) on the gap 4 side are inclined surfaces. In this case, the angle formed between the exposed surface 61a of the semiconductor laser element 1 and the front end surface of the pad electrode 70 is larger than the angle formed between the exposed surface 61a of the semiconductor laser element 1 and the inner surface of the joining member 3 (fillet 3a).
  • the gap 4 extends in the direction perpendicular to the paper surface of FIG. That is, the gap 4 is columnar and extends in a direction perpendicular to both the lamination direction of the semiconductor lamination structure 20 in the semiconductor laser element 1 and the cavity length direction.
  • FIGS. 6A to 6G are cross-sectional views of each step in the method of manufacturing the semiconductor laser device 1 according to the first embodiment. 6A to 6G, (a) shows the cross section (cross section of the current injection region) corresponding to FIG. 2A, and (b) shows the cross section (cross section of the current non-injection region at the front end) corresponding to FIG. 2B.
  • the substrate 10 is prepared, and the semiconductor laminated structure 20 including the active layer 22 is formed on the substrate 10 .
  • an n-type semiconductor layer 21, an active layer 22, a p-type semiconductor layer 23, and a p-type contact layer 24 are sequentially formed on a substrate 10, which is a wafer of an n-GaAs substrate, by a crystal growth technique based on metalorganic chemical vapor deposition (MOCVD).
  • MOCVD metalorganic chemical vapor deposition
  • a window region 22a is formed only in a portion corresponding to the front end portion of the semiconductor laminated structure 20 in the resonator length direction.
  • the window regions 22 a are formed by diffusing holes in the active layer 22 .
  • the window region 22a is formed by the hole diffusion method, the method is not limited to this. It should be noted that the window regions may not be formed at the front and rear ends of the semiconductor laser device 1 .
  • openings 30 are formed in the p-type contact layer 24 to define the ridge portion 1R and the wing portions 40 .
  • a mask made of SiO 2 or the like is formed in a predetermined pattern on the p-type contact layer 24 by photolithography, and then the opening 30 is formed by wet etching.
  • a lateral groove portion 31 is formed to form a convex portion 5a in the p-type contact layer 24 corresponding to the ridge portion 1R, and a convex portion 5b is formed in the p-type contact layer 24 corresponding to the wing portion 40.
  • the front groove 32 is formed in the p-type contact layer 24 without forming the projection 5a at the front end (current non-injection region) of the semiconductor laser device 1 . Note that the front groove portion 32 and the rear groove portion 33 may not be formed.
  • recesses may be separately formed in the p-type contact layer 24 in portions corresponding to the separation grooves 20c when singulated.
  • the recesses are formed on both sides of the semiconductor laminated structure 20 and extend in the resonator length direction when viewed from above.
  • a separation groove 20c having an inclined surface is formed on the side surface of the semiconductor laminated structure 20.
  • a mask made of SiO 2 or the like is formed in a predetermined pattern on the p-type semiconductor layer 23 by photolithography, and then the p-type semiconductor layer 23 and the n-type semiconductor layer 21 are etched by wet etching from the p-type semiconductor layer 23 to the middle.
  • a sulfuric acid-based etchant can be used as an etchant for forming the separation grooves 20c.
  • the etching liquid is not limited to the sulfuric acid-based etching liquid, and may be an organic acid-based etching liquid or an ammonia-based etching liquid.
  • the separation groove 20c is formed by isotropic wet etching. This makes it possible to form an inclined surface on the side surface of the semiconductor laminated structure 20 and form a constricted structure on the side surface of the semiconductor laminated structure 20 .
  • a SiN film is deposited as an insulating film 50 on the entire surface of the substrate 10, and then the insulating film 50 is removed in a portion corresponding to the current injection region using a photolithography technique and an etching technique to form an opening 50a. Note that, as shown in FIG. 6E (b), the insulating film 50 corresponding to the non-current-injection region is not removed, and the opening 50a is not formed in the insulating film 50 corresponding to the non-current-injection region.
  • the etching of the insulating film 50 wet etching using a hydrofluoric acid-based etchant or dry etching by reactive ion etching (RIE) can be used.
  • RIE reactive ion etching
  • the insulating film 50 is a SiN film, it is not limited to this, and may be a SiO 2 film or the like.
  • the p-side electrode layer 61 is formed above the semiconductor laminated structure 20, and then the pad electrode 70 is formed above the p-side electrode layer 61.
  • a p-side electrode layer 61 composed of a laminated film of a Ti film, a Pt film and an Au film is formed on the p-type contact layer 24 of the semiconductor laminated structure 20 by electron beam evaporation.
  • a pad electrode 70 made of an Au plating film is formed on the p-side electrode layer 61 using the p-side electrode layer 61 as a base electrode.
  • the pad electrode 70 is formed so that at least a part of the front end surface of the pad electrode 70 is recessed by patterning using a resist mask.
  • the p-side electrode layer 61 is formed over substantially the entire length in the cavity length direction, the pad electrode 70 is not formed over the entire length in the cavity length direction and is not formed at the front end.
  • a resist 80 resist mask having a predetermined shape is formed on the p-side electrode layer 61 so as to partially expose the p-side electrode layer 61 .
  • the pad electrode 70 is formed across the exposed p-side electrode layer 61 and the resist 80 .
  • an Au plated film is formed using the p-side electrode layer 61 as a base electrode by electroplating, and then the Au plated film in the vicinity of the front end portion of the semiconductor laminated structure 20 is selectively removed using a photolithography technique, an etching technique, and a lift-off technique, thereby forming the pad electrode 70 having the shape shown in FIG.
  • the resist 80 is removed.
  • the surface of the p-side electrode layer 61 is exposed to form an exposed surface 61a.
  • the thickness of the pad electrode 70 should be thicker than the thickness of the resist 80.
  • the pad electrode 70 (Au plated film) is formed so as to cover the end of the resist 80 , so that the eaves 71 can be formed at the front end of the pad electrode 70 .
  • the pad electrode 70 having the eaves 71 at the front end can be formed.
  • the angle ⁇ of the inclined surface of the concave portion 70a of the pad electrode 70 is 65 ⁇ 15°
  • the length d of the eaves portion 71 of the pad electrode 70 is 0.4 ⁇ m to 2.0 ⁇ m.
  • the thickness of the resist 80 is, for example, 1.8 ⁇ m.
  • an n-side electrode layer 62 is formed on the lower surface of the substrate 10.
  • the n-side electrode layer 62 is formed on the bottom surface of the substrate 10 by sequentially forming an AuGe film, a Ni film, an Au film, a Ti film, a Pt film, and an Au film from the substrate 10 side.
  • the substrate 10 (wafer) on which the semiconductor laminated structure 20 having a predetermined shape is formed is separated into a plurality of bars by dicing or cleaving using a blade, and then the separation grooves 20c are used as cutting portions to separate the chips.
  • the semiconductor laser element 1 in the form of individual pieces can be produced.
  • the semiconductor laser device 100 shown in FIGS. 3 to 5 can be manufactured by joining the semiconductor laser element 1 to the heat sink 2 by junction-down mounting with the joining member 3 .
  • the liquid bonding member 3 since the liquid bonding member 3 is pressed by the semiconductor laser element 1, the liquid bonding member 3 protrudes from between the semiconductor laser element 1 and the heat sink 2, and is connected to the bonding member 3 at the front end of the semiconductor laser element 1.
  • the semiconductor laser element 1 according to the present embodiment since the eaves 71 are formed at the front end of the pad electrode 70, the liquid bonding member 3 does not wrap around the protruding eaves 71. As a result, as shown in FIG. 5, the bonding member 3 does not come into contact with the front end surface of the pad electrode 70, so that the gap 4 is formed.
  • FIG. 8 is an SEM image of the semiconductor laser device 100 actually manufactured in this manner. As shown in FIG. 8, in the semiconductor laser device 100, a gap 4 is formed between the bonding member 3 and the front end surface of the pad electrode 70 in the longitudinal section parallel to the resonator length direction of the semiconductor laser element 1.
  • FIG. 9 is a cross-sectional view showing the configuration of a semiconductor laser device 100X of a comparative example.
  • FIG. 10 is a cross-sectional view showing the configuration of the semiconductor laser device 100 according to the first embodiment. 10 is a cross-sectional view corresponding to FIG.
  • the bonding member 3X that bonds the semiconductor laser element 1X and the heat sink 2 is connected to the front end of the semiconductor laser element 1X in order to suppress the occurrence of COD.
  • AuSn solder is used as the joint member 3X.
  • the front end surface of the pad electrode 70X of the semiconductor laser element 1X is a vertical surface
  • the bonding member 3X (fillet 3a) covers the front end surface of the pad electrode 70X and also covers the entire exposed surface 61a (that is, the surface of the p-side electrode layer 61) of the semiconductor laser element 1X. That is, the bonding member 3X connected to the front end portion of the semiconductor laser element 1X fills the front end surface of the pad electrode 70X and the peripheral region of the exposed surface 61a without gaps.
  • the bonding member 3X, the pad electrode 70X, the p-side electrode layer 61, and the new alloy layer have different coefficients of linear expansion. That is, there is a difference in coefficient of linear expansion between the bonding member 3X, the pad electrode 70X, the p-side electrode layer 61, and the new alloy layer. Therefore, in the semiconductor laser device 100X, when the temperature changes, shear stress is generated between the members due to the difference in coefficient of linear expansion between the members. In particular, as shown at point P in FIG. 9, if the corner between the front end surface of the pad electrode 70X and the exposed surface 61a of the p-side electrode layer 61 is filled with the bonding member 3X, a large shear stress is generated at this point P.
  • shear stress is applied to the front end portion of the semiconductor laser element 1X to generate shear strain, and this shear strain progresses to the light emitting region inside the semiconductor laser element 1X. This may reduce the long-term reliability of the semiconductor laser device 1X.
  • the bonding member 3 (fillet 3a) is connected to the exposed surface 61a of the front end portion of the semiconductor laser element 1, but since at least a part of the front end surface of the pad electrode 70 is recessed, a gap 4 (air gap) is formed between the bonding member 3 and the front end surface of the pad electrode 70.
  • a portion of the front end surface of pad electrode 70 is recessed by forming eaves portion 71 at the front end portion of pad electrode 70 .
  • the bonding member 3 and a portion of the exposed surface 61a of the p-side electrode layer 61 are separated from each other due to the existence of the gap 4 . Therefore, the alloy layer formed between the bonding member 3 and the exposed surface 61a of the p-side electrode layer 61 can be reduced.
  • the semiconductor laser device 100 even if the bonding member 3 is connected to the front end portion of the semiconductor laser element 1 in order to suppress the occurrence of COD, the stress applied to the semiconductor laser element 1 can be relaxed. As a result, deterioration in long-term reliability of the semiconductor laser device 1 can be suppressed.
  • the semiconductor laser element 1 has the ridge portion 1R extending in the cavity length direction, and in the vertical cross section of the exposed surface 61a of the semiconductor laser element 1 perpendicular to the cavity length direction, the bonding member 3 is connected to the exposed surface 61a over at least the entire width of the ridge portion 1R.
  • the bonding member 3 (fillet 3a) on the exposed surface 61a is formed not only over part of the width of the ridge portion 1R but over the entire width of the ridge portion 1R (that is, over the entire light emitting region). That is, heat dissipation in the ridge portion 1R can be promoted.
  • the bonding member 3 is connected to the exposed surface 61a up to the position of the front end surface of the semiconductor laminated structure 20 of the semiconductor laser element 1.
  • the shear strain can be effectively reduced by the gap 4 while the heat at the front end of the semiconductor laser element 1 is reliably radiated. Thereby, the long-term reliability of the semiconductor laser device 1 can be improved.
  • the distance from the front end face 1a (light emitting end face) of the semiconductor laser element 1 to the front end face (pad electrode end) of the pad electrode 70 is defined as L, and the COD breakdown current is measured by changing the distance L, and the result shown in FIG. 11 is obtained.
  • the distance L between the front end face 1a of the semiconductor laser element 1 and the front end face of the pad electrode 70 the easier it is to form the fillet 3a connected to the front end of the semiconductor laser element 1, resulting in a higher COD breakdown current.
  • the distance L should be 15 ⁇ m or less from the viewpoint of obtaining a high COD breakdown current.
  • the interval L is preferably 5 ⁇ m or more.
  • the distance L between the front end surface 1a of the semiconductor laser element 1 and the front end surface of the pad electrode 70 should be 5 ⁇ m or more and 15 ⁇ m or less.
  • the front end surface 1a of the semiconductor laser element 1 does not protrude from the front end surface of the heat sink 2 as shown in FIG. 10, but this is not the only option.
  • the front end surface 1a of the semiconductor laser element 1 may protrude from the front end surface of the heat sink 2, as in a semiconductor laser device 100A shown in FIG.
  • the semiconductor laser element 1 may be mounted so that the front end surface 1 a protrudes from the front end surface of the heat sink 2 .
  • the front end surface of the pad electrode 70 is partially recessed by forming the eaves portion 71 on the pad electrode 70, but this is not the only option.
  • the front end surface of the pad electrode 70B may be partially recessed without forming the eaves portion 71 on the pad electrode 70B.
  • the entire front end surface of the pad electrode 70B is an inclined surface.
  • the cross-sectional shape of the gap 4 between the bonding member 3 and the front end face of the pad electrode 70B is triangular. That is, the cross-sectional shape of the gap 4 is not limited to a trapezoidal shape. Note that the cross-sectional shape of the gap 4 may be a shape other than trapezoidal and triangular.
  • the semiconductor laser element 1 is not warped, but the semiconductor laser element 1 may be warped in the cavity length direction.
  • the semiconductor laser element 1 is preferably warped so that the central portion is recessed with respect to the surface bonded to the heat sink 2 in the resonator length direction.
  • the bonding member 3 may creep up onto the front end surface 1a (light emitting end surface) of the semiconductor laser element 1.
  • the bonding member 3 may enter the curved inside of the convex semiconductor laser element 1, and the bonding member 3 may not be connected to the exposed surface 61a of the semiconductor laser element 1. Therefore, the semiconductor laser element 1 mounted on the heat sink 2 should preferably be recessed along the cavity length direction, as shown in FIG. 14(b).
  • the central portion of the semiconductor laser element 1 in the cavity length direction is warped in a concave shape and that the amount of warp is small.
  • the bonding member 3 pressed by the semiconductor laser element 1 swells on both end sides of the semiconductor laser element 1, so that bonding between the exposed surface 61a of the semiconductor laser element 1 and the bonding member 3 can be promoted.
  • the amount of warpage of the semiconductor laser device 1 is preferably 1 ⁇ m or more and 3 ⁇ m or less.
  • the layer structure of the semiconductor laser device 1 in Embodiment 1 is an example of Example 1, and is not limited to this.
  • the layer structure of the semiconductor laser device 1 in the first embodiment may be configured as follows as a second example.
  • the semiconductor laser device 1 of Example 2 configured as described above also has the same effect as the semiconductor laser device 1 of Example 1.
  • the p-type contact layer 24 is a p-type GaAs layer made of p-GaAs with a thickness of 0.25 ⁇ m.
  • the semiconductor laser device 1 of Example 2 configured as described above also has the same effect as the semiconductor laser device 1 of Example 1.
  • the layer structure of the semiconductor laser device 1 in Embodiment 1 may be configured as follows as Example 3.
  • the p-type cladding layer is a p-type AlGaAs layer of p-Al 0.70 Ga 0.30 As with a thickness of 0.55 ⁇ m
  • the p-type contact layer 24 is a p-type GaAs layer made of p-GaAs with a thickness of 0.25 ⁇ m.
  • the semiconductor laser device 1 of Example 3 constructed as described above also has the same effect as the semiconductor laser device 1 of Example 1.
  • FIG. Furthermore, the window region 22a, the front groove portion 32 and the rear groove portion 33 are not formed in the semiconductor laser device 1 of Example 3.
  • FIG. Further, in the semiconductor laser device 1 of Example 3, the n-side first barrier layer and the p-side first barrier layer having Al compositions higher than those of the p-side second barrier layer and the n-side second barrier layer are not formed. Thereby, the operating voltage can be reduced.
  • the n-side second barrier layer is a single layer, and n-type AlGaAs is not formed. As a result, the waveguide loss can be reduced, and the slope efficiency can be improved.
  • FIG. 16 is a plan view of a semiconductor laser device 1A according to the second embodiment.
  • 17A to 17C are cross-sectional views of a semiconductor laser device 1A according to the second embodiment.
  • 17A, 17B, and 17C show cross sections along line XVIIA-XVIIA in FIG. 16, line XVIIB-XVIIB in FIG. 16, and line XVIIC-XVIIC in FIG. 16, respectively.
  • FIG. 18 is an enlarged cross-sectional view of the semiconductor laser device 101 according to the second embodiment.
  • FIG. 18 is a cross-sectional view corresponding to FIG.
  • the semiconductor laser element 1A and the semiconductor laser device 101 according to the present embodiment have a configuration in which the p-side electrode layer 61 is used as the first p-side electrode layer in the semiconductor laser element 1 and the semiconductor laser device 100 according to the first embodiment, and a second p-side electrode layer 63 is further provided. Specifically, the second p-side electrode layer 63 is provided on the semiconductor laser element 1A.
  • the second p-side electrode layer 63 is formed on the pad electrode 70 and on the p-side electrode layer 61 as well. Therefore, in the semiconductor laser device 101, the second p-side electrode layer 63 is formed on the surface of the pad electrode 70 facing the heat sink 2 and the surface of the p-side electrode layer 61 facing the heat sink 2, as shown in FIG.
  • a second p-side electrode layer 63 is formed on the p-side electrode layer 61 at the front end of the semiconductor laser device 1A. Therefore, in the present embodiment, the exposed surface at the front end portion of the semiconductor laser element 1A is not the surface of the p-side electrode layer 61 but the surface of the second p-side electrode layer 63 . Therefore, the joining member 3 (fillet 3a) connected to the front end portion of the semiconductor laser element 1A is connected not to the p-side electrode layer 61 but to the second p-side electrode layer 63 .
  • the second p-side electrode layer 63 is a metal layer made of a metal material.
  • the second p-side electrode layer 63 is, for example, a single layer film or multilayer film made of at least one of Pt, Ti, Cr, Ni, Mo and Au.
  • the second p-side electrode layer 63 is composed of the same multilayer film as the p-side electrode layer 61 . Therefore, the second p-side electrode layer 63 is a multilayer film having a three-layer structure in which a Ti film, a Pt film and an Au film are laminated in this order from the pad electrode 70 side.
  • the semiconductor laser element 1A and the semiconductor laser device 101 according to the present embodiment have the same configurations as the semiconductor laser element 1 and the semiconductor laser device 100 according to the first embodiment, except that the second p-side electrode layer 63 is added.
  • the bonding member 3 (fillet 3a) is connected to the exposed surface 61a of the front end portion of the semiconductor laser element 1A, but at least a part of the front end surface of the pad electrode 70 is formed so as to be recessed.
  • a gap 4 (air gap) is formed between the bonding member 3 and the front end face of the pad electrode 70 .
  • the second p-side electrode layer 63 is formed on the pad electrode 70 and the p-side electrode layer 61, and the joining member 3 (fillet 3a) connected to the front end portion of the semiconductor laser element 1A is connected to the second p-side electrode layer 63.
  • the semiconductor laser device 101 according to the present embodiment can improve long-term reliability as compared with the semiconductor laser device 100 according to the above embodiment.
  • the front facet 1a of the semiconductor laser element 1A does not protrude from the front facet of the heat sink 2, but this is not the only option.
  • the front end surface 1a of the semiconductor laser element 1A may protrude from the front end surface of the heat sink 2.
  • the semiconductor laser element 1A may be mounted so that the front end surface 1a protrudes from the front end surface of the heat sink 2.
  • the semiconductor laser device 1A according to the present embodiment can be manufactured according to the manufacturing method of the semiconductor laser device 1 according to the first embodiment.
  • FIGS. 6A to 6F can be manufactured by the same method as in the first embodiment.
  • a second p-side electrode layer 63 is formed on the pad electrode 70 and the p-side electrode layer 61, as shown in (a) and (b) of FIG. 20A.
  • a second p-side electrode layer 63 composed of a laminated film of a Ti film, a Pt film and an Au film is formed on the pad electrode 70 and the p-side electrode layer 61 by electron beam evaporation.
  • an n-side electrode layer 62 is formed on the lower surface of the substrate 10 .
  • the n-side electrode layer 62 is formed on the bottom surface of the substrate 10 by sequentially forming an AuGe film, a Ni film, an Au film, a Ti film, a Pt film, and an Au film from the substrate 10 side.
  • the substrate 10 (wafer) on which the semiconductor laminated structure 20 having a predetermined shape is formed is separated into a plurality of bars, and further chip separation is performed in the same manner as in the first embodiment, whereby individual semiconductor laser elements 1A can be manufactured.
  • FIG. 20A and 20B (a) shows the cross section (cross section of the current injection region) corresponding to FIG. 17A, and (b) shows the cross section (cross section of the current non-injection region at the front end) corresponding to FIG. 17B.
  • FIG. 21 is a plan view of a semiconductor laser device 1B according to Embodiment 3.
  • FIG. 22A to 22C are cross-sectional views of the semiconductor laser device 102 according to the second embodiment. 22A, 22B, and 22C show a part of the cross section of the semiconductor laser device 102 according to the third embodiment taken along lines XIIIA-XXIIA in FIG. 21, XIIIB-XXIIB in FIG. 21, and XIIIC-XXIIC in FIG. 21, respectively.
  • hatching is applied for convenience in order to indicate the position of the second pad electrode 90 .
  • the semiconductor laser element 1B and the semiconductor laser device 102 according to the present embodiment have a configuration in which the pad electrode 70 is used as the first pad electrode in the semiconductor laser element 1A and the semiconductor laser device 101 according to the second embodiment, and a second pad electrode 90 is further provided. Specifically, the second pad electrode 90 is provided on the semiconductor laser element 1B.
  • the second pad electrodes 90 are formed on both sides of the optical waveguide extending in the resonator length direction of the semiconductor laser device 1B.
  • the second pad electrodes 90 are formed on both sides of the ridge portion 1R as viewed from above, as shown in FIG. Specifically, two second pad electrodes 90 are formed so as to sandwich the ridge portion 1R.
  • the two second pad electrodes 90 are formed in parallel so as to extend in the resonator length direction of the semiconductor laser device 1B.
  • the width of each second pad electrode 90 is constant, and the top view shape of each second pad electrode 90 is an elongated rectangle.
  • the second pad electrode 90 is formed on the heat sink 2 side of the pad electrode 70 (first pad electrode). That is, the second pad electrode 90 is formed on the surface of the pad electrode 70 opposite to the p-side electrode layer 61 side. Therefore, the pad electrode 70 is sandwiched between the p-side electrode layer 61 and the second pad electrode 90 .
  • the semiconductor laser element 1B and the semiconductor laser device 102 according to the present embodiment have the same configurations as the semiconductor laser element 1A and the semiconductor laser device 101 according to the second embodiment except that the second pad electrode 90 is added.
  • the bonding member 3 (fillet 3a) is connected to the exposed surface 61a of the front end portion of the semiconductor laser element 1B, but at least a part of the front end surface of the pad electrode 70 is formed so as to be recessed.
  • a gap 4 (air gap) is formed between the bonding member 3 and the front end face of the pad electrode 70 .
  • the second p-side electrode layer 63 is formed on the pad electrode 70 and the p-side electrode layer 61, and the joining member 3 (fillet 3a) connected to the front end portion of the semiconductor laser element 1B is connected to the second p-side electrode layer 63.
  • the second pad electrode 90 is formed on the heat sink 2 side of the pad electrode 70, and the second pad electrode 90 is formed on both sides of the optical waveguide extending in the cavity length direction of the semiconductor laser element 1B.
  • the lateral expansion of the bonding member 3 between the semiconductor laser element 1B and the heat sink 2 can be restricted so that the bonding member 3 can be wetted and spread in the cavity length direction.
  • This can promote the formation of the fillet 3a of the joining member 3 in the ridge width region of the front end portion of the semiconductor laser element 1B. Therefore, the heat generated in the ridge portion 1R (ridge width region) at the front end of the semiconductor laser device 1B is the highest when the semiconductor laser device 1B emits light.
  • the heat generated in the ridge width region at the front end portion of the semiconductor laser device 1B can be effectively dissipated.
  • the front end surface 1a of the semiconductor laser element 1B may protrude from the front end surface of the heat sink 2 also in the semiconductor laser device 102 of the present embodiment.
  • the semiconductor laser device 1B in the present embodiment can be manufactured according to the manufacturing method of the semiconductor laser devices 1 and 1A according to the first and second embodiments.
  • FIGS. 6A to 6F can be manufactured by the same method as in the first and second embodiments.
  • a pair of second pad electrodes 90 are formed on the pad electrode 70, and then a second p-side electrode layer 63 is formed on the pad electrode 70 so as to cover the second pad electrode 90, and a second p-side electrode layer 63 is formed on the p-side electrode layer 61.
  • an n-side electrode layer 62 is formed on the lower surface of the substrate 10 in the same manner as in the first and second embodiments.
  • the substrate 10 (wafer) on which the semiconductor laminated structure 20 having a predetermined shape is formed is separated into a plurality of bars in the same manner as in the second embodiment, and further chip separation is performed, whereby individual semiconductor laser elements 1B can be manufactured.
  • each second pad electrode 90 is formed continuously along the cavity length direction, but this is not the only option.
  • each second pad electrode 90D may be intermittently formed along the cavity length direction. That is, the second pad electrode 90D may be partially divided in the resonator length direction.
  • each second pad electrode 90 has an elongated rectangular shape, but it is not limited to this.
  • protrusions that protrude inward may be formed at both ends of the second pad electrode 90E in the top view in the longitudinal direction.
  • the bonding member 3 wetted and spread in the cavity length direction advances inward at the front end portion of the semiconductor laser element. Therefore, the fillet 3a of the joining member 3 can be easily formed in the ridge width region of the front end portion of the semiconductor laser element 1E.
  • the semiconductor laser element is configured to emit infrared laser light, but the present invention is not limited to this.
  • the semiconductor laser element may be configured to emit visible light or ultraviolet laser light.
  • the semiconductor laser device is made of the AlGaInAs-based III-V group semiconductor material, but the present invention is not limited to this.
  • the semiconductor laser element may be a nitride semiconductor laser element made of a nitride semiconductor material.
  • the present disclosure also includes forms obtained by applying various modifications that a person skilled in the art can come up with to the above embodiments, and forms realized by arbitrarily combining the constituent elements and functions of each embodiment within the scope of the present disclosure.
  • the semiconductor laser device and semiconductor laser element according to the present disclosure can be applied to light sources for various products, including laser processing devices.

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  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Geometry (AREA)
  • Semiconductor Lasers (AREA)
PCT/JP2023/001051 2022-01-24 2023-01-16 半導体レーザ装置及び半導体レーザ素子の製造方法 Ceased WO2023140224A1 (ja)

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06196824A (ja) * 1992-12-24 1994-07-15 Furukawa Electric Co Ltd:The 半導体素子の製造方法
JPH0745811A (ja) * 1993-08-03 1995-02-14 Sharp Corp 光集積回路素子の組立構造
JP2002109774A (ja) * 2000-10-02 2002-04-12 Ricoh Co Ltd 光ピックアップ
JP2003218450A (ja) * 2002-01-21 2003-07-31 Sumitomo Electric Ind Ltd 半導体光集積素子
JP2007027572A (ja) * 2005-07-20 2007-02-01 Sony Corp 半導体発光装置およびその製造方法
JP2009289775A (ja) * 2008-05-27 2009-12-10 Sony Corp 発光装置及び発光装置の製造方法
JP2010027942A (ja) * 2008-07-23 2010-02-04 Sony Corp 半導体レーザ装置
WO2011102064A1 (ja) * 2010-02-19 2011-08-25 Jsr株式会社 ｎ型半導体層上の電極の形成方法
US20190089125A1 (en) * 2016-03-03 2019-03-21 Osram Opto Semiconductors Gmbh Optoelectronic lighting device, carrier for an optoelectronic semiconductor chip, and optoelectronic lighting system

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06196824A (ja) * 1992-12-24 1994-07-15 Furukawa Electric Co Ltd:The 半導体素子の製造方法
JPH0745811A (ja) * 1993-08-03 1995-02-14 Sharp Corp 光集積回路素子の組立構造
JP2002109774A (ja) * 2000-10-02 2002-04-12 Ricoh Co Ltd 光ピックアップ
JP2003218450A (ja) * 2002-01-21 2003-07-31 Sumitomo Electric Ind Ltd 半導体光集積素子
JP2007027572A (ja) * 2005-07-20 2007-02-01 Sony Corp 半導体発光装置およびその製造方法
JP2009289775A (ja) * 2008-05-27 2009-12-10 Sony Corp 発光装置及び発光装置の製造方法
JP2010027942A (ja) * 2008-07-23 2010-02-04 Sony Corp 半導体レーザ装置
WO2011102064A1 (ja) * 2010-02-19 2011-08-25 Jsr株式会社 ｎ型半導体層上の電極の形成方法
US20190089125A1 (en) * 2016-03-03 2019-03-21 Osram Opto Semiconductors Gmbh Optoelectronic lighting device, carrier for an optoelectronic semiconductor chip, and optoelectronic lighting system

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