JP6928440B2 - Semiconductor laser device - Google Patents

Description

The present invention relates to a semiconductor laser device.

As a conventional semiconductor laser device, for example, there is a semiconductor laser device described in Patent Document 1. In this semiconductor laser device, a laminated structure in which semiconductor laser elements fixed to a submount are laminated is arranged on an insulating substrate. This semiconductor laser device has a back cooling structure in which cooling is performed on the opposite side of the laser beam oscillation direction. The submount is solder-bonded to the conductor pattern on the insulating substrate, and the heat generated by the semiconductor laser element during laser oscillation is dissipated to the insulating substrate side via the submount.

Japanese Unexamined Patent Publication No. 11-121859

In recent years, it has been required to improve the light density of a semiconductor laser device having the back cooling structure as described above. In order to improve the light density, it is necessary to narrow the stacking pitch of the semiconductor laser elements in the laminated structure arranged on the insulating substrate and to highly integrate the semiconductor laser elements. However, if the stacking pitch of the semiconductor laser element is narrowed, the distance between the submounts adjacent to each other in the stacking direction becomes narrower, so that there is a possibility that leakage due to the solder used for joining the submount and the conductor pattern is likely to occur. ..

The present invention has been made to solve the above problems, and an object of the present invention is to provide a semiconductor laser device capable of suppressing leakage between submounts and highly integrating a semiconductor laser element.

The semiconductor laser apparatus according to one aspect of the present invention includes a laminated structure in which a heat-conducting insulating substrate having a conductor pattern formed on one surface side and a laser unit having a semiconductor laser element fixed to a submount are laminated. The laminated structure has , At least one of the submount and the conductor pattern is provided with a protruding portion protruding toward the other side, and the width of the protruding portion with respect to the stacking direction is smaller than the width of the submount with respect to the stacking direction.

In this semiconductor laser device, at the joint portion between the submount and the conductor pattern, a protruding portion is provided on at least one of the submount and the conductor pattern. This protruding portion forms a solder relief portion between the submount and the insulating substrate, and the solder that melts during joining flows along the shape of the protruding portion, so that the solder is soldered in the stacking direction of the laminated structure. Can be suppressed from spreading. Therefore, even when the stacking pitch of the semiconductor laser element is narrow, the occurrence of leakage due to soldering can be suppressed, and high integration of the semiconductor laser element in the laminated structure can be realized.

Further, the laser unit may be formed by fixing the semiconductor laser element only on one surface side of the submount. By doing so, it is possible to realize high integration of the semiconductor laser element in the laminated structure as compared with the case where the semiconductor laser element is fixed on both sides of the submount. Further, even when the semiconductor laser element is highly integrated, the occurrence of leakage due to the solder is effectively suppressed by the relief portion of the solder formed between the submount and the insulating substrate.

Further, the protruding portion may be provided on the conductor pattern side by a conductive member provided in a protruding shape on one surface side of the insulating substrate. In this case, the protruding portion can be provided with a simple configuration, and the submount and the conductor pattern can be firmly joined at the joining portion.

Further, one surface side of the insulating substrate is an uneven surface, and the protruding portion may be provided on the conductor pattern side by the convex portion of the uneven surface. In this case, the protruding portion can be provided with a simple configuration, and the submount and the conductor pattern can be firmly joined at the joining portion.

Further, the protruding portion may be provided on the submount side by a protrusion provided on the end portion of the submount on the insulating substrate side. In this case, the protruding portion can be provided with a simple configuration, and the submount and the conductor pattern can be firmly joined at the joining portion.

Further, the protruding portion is provided on both the conductor pattern side and the submount side by the conductive member provided in a protrusion shape on one surface side of the insulating substrate and the protrusion provided on the end portion of the submount on the insulating substrate side. It may have been. By providing the protruding portions on both the conductor pattern side and the sub-mount side, it is possible to secure a large relief portion for the solder. Therefore, leakage due to solder can be suppressed more reliably.

Further, the protruding portion may have a trapezoidal cross section so that the hem expands toward the insulating substrate side. By doing so, it is possible to improve the heat dissipation from the submount side to the insulating substrate side.

According to the present invention, leakage between submounts can be suppressed, and a semiconductor laser device can be highly integrated.

It is a schematic cross-sectional view which shows the semiconductor laser apparatus which concerns on 1st Embodiment. It is a schematic cross-sectional view which shows the structure of a laser unit. It is an enlarged sectional view of the main part which shows the joint part of a submount and a conductor pattern. FIG. 5 is an enlarged cross-sectional view of a main part showing a joint portion between a submount of the semiconductor laser apparatus according to the second embodiment and a conductor pattern. FIG. 5 is an enlarged cross-sectional view of a main part showing a joint portion between a submount of a semiconductor laser apparatus according to a third embodiment and a conductor pattern. FIG. 5 is an enlarged cross-sectional view of a main part showing a joint portion between a submount of a semiconductor laser device and a conductor pattern according to a fourth embodiment. It is sectional drawing which shows another example of the protruding part. It is sectional drawing which shows another example of the protruding part.

Hereinafter, preferred embodiments of the semiconductor laser device according to one aspect of the present invention will be described in detail with reference to the drawings.
[First Embodiment]

FIG. 1 is a schematic cross-sectional view showing the configuration of the semiconductor laser device according to the first embodiment. As shown in the figure, the semiconductor laser device 1 is a laminated structure 7 in which a heat sink 2, an insulating substrate 3, a laser unit 6 composed of a semiconductor laser bar (semiconductor laser element) 4 and a submount 5 are laminated. It is configured with and. The semiconductor laser device 1 has a back surface cooling structure in which cooling is performed on the opposite side of the laser beam oscillation direction, and heat generated by the semiconductor laser bar 4 during laser oscillation is heat-sinked via a submount 5 and an insulating substrate 3. The heat is dissipated to the two sides. The heat sink 2 is formed in the shape of a thick plate by a material having high heat conductivity such as copper (Cu). A flow path such as cooling water may be formed inside the heat sink.

The insulating substrate 3 is formed in a plate shape by a material having heat conductivity and electrical insulation such as aluminum nitride (AlN). Examples of other forming materials for the insulating substrate 3 include silicon carbide (SiC) and diamond. A conductor pattern 8 is provided on one side of the insulating substrate 3. Further, a metal layer 9 is provided on the other surface side of the insulating substrate 3. The other surface side of the insulating substrate 3 is joined to the one surface side of the heat sink 2 over the entire surface. For joining the heat sink 2 and the insulating substrate 3, for example, indium (In) solder, SnAgCu solder, or the like is used from the viewpoint of lead-free.

The conductor pattern 8 is composed of, for example, four metal layers of titanium (Ti) / copper (Cu) / nickel (Ni) / gold (Au) laminated in order from the surface side of the insulating substrate 3. The conductor pattern 8 is formed, for example, by vapor deposition using a predetermined mask. Similar to the conductor pattern 8, the metal layer 9 is composed of four metal layers of titanium (Ti) / copper (Cu) / nickel (Ni) / gold (Au). The metal layer 9 is formed by, for example, thin film deposition. The thickness of the conductor pattern 8 is equal to or slightly larger than the thickness of the metal layer 9. Thereby, the warp of the insulating substrate 3 due to the formation of the conductor pattern 8 and the metal layer 9 can be suppressed.

The laminated structure 7 is configured by laminating a plurality of laser units 6. The laminated structure 7 is arranged on one side of the insulating substrate 3 so that the laminating direction of the laser unit 6 and the in-plane direction of the insulating substrate 3 coincide with each other. As shown in FIG. 2, the laser unit 6 is a unit in which the semiconductor laser bar 4 is fixed only on one side of the submount 5. The laser units 6 and 6 adjacent to each other in the stacking direction are joined so that the submount 5 and the semiconductor laser bar 4 are alternately arranged in the same direction (see FIG. 1).

For joining the laser units 6 and 6, for example, solder having a melting point higher than that used for joining the heat sink 2 and the insulating substrate 3 is used. Examples of such solder include gold tin solder. In the laminated structure 7, the laser unit 6 located at one of the laminated ends of the laminated structure 7 is additionally sub-mounted so as to sandwich the semiconductor laser bar 4 with the sub-mount 5 in the laser unit 6. 5 are joined. For joining the laser units 6 and 6, solder having a melting point higher than that used for joining the heat sink 2 and the insulating substrate 3 is used. Examples of such solder include gold tin solder.

The submount 5 is formed in a plate shape by a material having thermal conductivity and electrical conductivity such as copper tungsten (CuW). Examples of other constituent materials of the submount 5 include aluminum nitride (AlN), silicon carbide (SiC), tungsten (W), copper molybdenum (MoCu) composite material, and copper diamond composite material. On the surface of the submount 5, a two-layer plating layer made of nickel (Ni) / gold (Au) or a three-layer plating layer made of chromium (Cr) / platinum (Pt) / gold (Au) is formed. May be good. In each submount 5, one end surface 5a (see FIG. 2) facing the insulating substrate 3 (conductor pattern 8) side is soldered to the conductor pattern 8 on the insulating substrate 3. For example, indium (In) solder is used for joining each submount 5 and the conductor pattern 8. The details of this joint portion will be described later.

The semiconductor laser bar 4 has, for example, a plate shape. As shown in FIG. 2, the front end surface of the semiconductor laser bar 4 is an emission end surface 4a having a plurality of light emitting regions. The semiconductor laser bar 4 is joined to one side of the submount 5 so that the exit end surface 4a and the other end surface 5b of the submount 5 are flush with each other. For joining the semiconductor laser bar 4 and the submount 5, solder having a melting point higher than that used for joining the heat sink 2 and the insulating substrate 3 is used as in the case of joining the laser units 6 and 6. Examples of such solder include gold tin solder.

The semiconductor laser bar 4 has a substrate made of a compound semiconductor, an active layer is located at a position corresponding to a light emitting region, and clad layers are located on both sides of the active layer. Examples of the substrate material include gallium arsenide (GaAs), gallium nitride (GaN), aluminum gallium arsenide (AlGaAs), (gallium phosphide) GaP, gallium aluminum nitride (AlGaN), and indium phosphide (InP). Be done. In this embodiment, for example, the main component of the substrate is gallium arsenide (GaAs). The active layer contains indium (In) in addition to gallium arsenide, and the clad layer contains aluminum (Al) in addition to gallium arsenide.

When driving the semiconductor laser device 1 as described above, the conductor pattern 8 (8A) connected to the submount 5 located at one of the laminated ends of the laminated structure 7 and the other laminated body of the laminated structure 7. A driving voltage is applied between the conductor pattern 8 (8B) connected to the submount 5 located at. As a result, a drive current is supplied to all the semiconductor laser bars 4 included in the laminated structure 7, and laser light is oscillated from each of the plurality of light emitting regions of the emission end surface 4a. The heat generated in the semiconductor laser bar 4 during laser oscillation is transferred from the adjacent submount 5 to the insulating substrate 3 and dissipated to the heat sink 2 side.

Subsequently, a detailed configuration of the joint portion between the submount 5 and the conductor pattern 8 described above will be described.

FIG. 3 is an enlarged cross-sectional view of a main part showing a joint portion between the submount and the conductor pattern. As shown in the figure, in the joint portion P, at least one of the submount 5 and the conductor pattern 8 is provided with a protruding portion 11 projecting toward the other party. In the present embodiment, the protruding portion 11 is provided on the conductor pattern 8 side by the conductive member 12 provided in a protruding shape on one surface side of the insulating substrate 3.

The conductive member 12 is made of a conductive member such as copper. The conductive member 12 is patterned between one surface side of the insulating substrate 3 and each submount 5 by, for example, thin-film deposition using a predetermined mask. The conductive member 12 has, for example, a rectangular cross section, and extends in the depth direction of the submount 5 (the depth direction of the paper surface in FIG. 2). The above-mentioned conductor pattern 8 made of a plurality of metal layers is provided on the top of the conductive member 12. Further, for example, a solder layer 13 made of the above-mentioned indium (In) solder is provided so as to cover the conductive member 12 and the conductor pattern 8.

The height of the protruding portion 11 from the one surface side of the insulating substrate 3 is, for example, about 0.05 mm to 0.5 mm. On the other hand, the width W1 of the protruding portion 11 with respect to the stacking direction of the laminated structure 7 is smaller than the width W2 of the submount 5 with respect to the stacking direction. For example, when the width W2 of the sub mount 5 is 0.25 mm, the width W1 of the protruding portion 11 is 0.05 mm or more and less than 0.24 mm, preferably 0.1 mm or more and less than 0.2 mm. As a result, the protruding portion 11 is located within a range that does not protrude from the submount 5 when viewed from the height direction of the submount 5 (normal direction of the insulating substrate 3), and the one end surface 5a of the submount 5 and the insulating substrate 3 Spaces S, which serve as escape portions for solder, are formed on both sides of the protruding portion 11 between the surface side and the side.

The hem portion (portion located on the insulating substrate 3) 13a of the solder layer 13 is preferably located within a range that does not protrude from the submount 5 when viewed from the height direction of the submount 5, but is an adjacent protruding portion. As long as it is sufficiently spaced from the hem portion 13a of the solder layer 13 in 11, it may slightly protrude from the submount 5.

In such a configuration without the protruding portion 11 (comparative example), a space S serving as a solder relief portion is not formed between the submount 5 and the insulating substrate 3. Therefore, it is conceivable that the solder that melts at the time of joining flows along one surface side of the insulating substrate 3 and comes into contact with the solder that joins the adjacent submount 5 and the conductor pattern 8.

On the other hand, in the semiconductor laser device 1, the protruding portion 11 forms a solder relief portion between the submount 5 and the insulating substrate 3, and the solder melted at the time of joining follows the shape of the protruding portion 11. Since it flows, it is possible to prevent the solder from spreading in the stacking direction of the laminated structure 7. Therefore, even when the stacking pitch of the semiconductor laser bar 4 is narrow, the occurrence of leakage due to soldering can be suppressed, and high integration of the semiconductor laser bar 4 in the laminated structure 7 can be realized.

Further, in the semiconductor laser device 1, a laser unit 6 in which the semiconductor laser bar 4 is fixed only on one surface side of the submount 5 is used. As a result, it is possible to realize high integration of the semiconductor laser bar 4 in the laminated structure 7 as compared with the case where the semiconductor laser bar 4 is fixed on both sides of the sub mount 5. Further, even when the semiconductor laser bar 4 is highly integrated, the occurrence of leakage due to the solder is effectively suppressed by the relief portion of the solder formed between the submount 5 and the insulating substrate 3.

Further, in the present embodiment, the protruding portion 11 is provided on the conductor pattern 8 side by the conductive member 12 provided in a protruding shape on one surface side of the insulating substrate 3. In this case, the protruding portion 11 can be provided with a simple configuration, and the submount 5 and the conductor pattern 8 can be firmly joined at the joining portion P. Since the solder layer 13 is provided so as to cover the conductive member 12 and the conductor pattern 8, the solder that melts at the time of joining flows to the insulating substrate 3 side according to the side shape of the protruding portion 11, so that the laminated structure 7 The spread of solder in the stacking direction is more reliably suppressed.
[Second Embodiment]

FIG. 4 is an enlarged cross-sectional view of a main part showing a joint portion between the submount of the semiconductor laser apparatus according to the second embodiment and the conductor pattern. As shown in the figure, in the second embodiment, the configuration of the joint portion P between the submount 5 and the conductor pattern 8 is different from that in the first embodiment. Other configurations are the same as those in the first embodiment. More specifically, in the second embodiment, the conductor pattern 8 is formed by the convex portion 14 of the concave-convex surface 3a provided by etching or the like on one surface side of the insulating substrate 3 instead of the vapor deposition of the conductive member. A protruding portion 11 is provided on the side. The conductor pattern 8 is provided on the top of the convex portion 14, and the solder layer 13 is provided so as to cover the convex portion 14 and the conductor pattern 8.

Even in such a configuration, the protruding portion 11 having a width W1 smaller than the width W2 of the submount 5 forms a solder relief portion between the submount 5 and the insulating substrate 3, and at the time of joining. Since the molten solder flows according to the shape of the protruding portion 11, it is possible to prevent the solder from spreading in the stacking direction of the laminated structure 7. Therefore, even when the stacking pitch of the semiconductor laser bar 4 is narrow, the occurrence of leakage due to soldering can be suppressed, and high integration of the semiconductor laser bar 4 in the laminated structure 7 can be realized. Further, the protruding portion 11 can be provided with a simple configuration, and the submount 5 and the conductor pattern 8 can be firmly joined at the joining portion P.
[Third Embodiment]

FIG. 5 is an enlarged cross-sectional view of a main part showing a joint portion between the submount of the semiconductor laser apparatus according to the third embodiment and the conductor pattern. As shown in the figure, in the third embodiment, the configuration of the joint portion P between the submount 5 and the conductor pattern 8 is further different from that in the first embodiment. Other configurations are the same as those in the first embodiment.

More specifically, in the third embodiment, the protruding portion 11 is provided on the submount 5 side by the protrusion 15 provided on the one end surface 5a on the insulating substrate 3 side of the submount 5. The protrusion 15 is formed, for example, by cutting the end portion of the submount 5. The solder layer 13 is provided so as to cover the protrusion 15 on the submount 5 side, and the conductor pattern 8 is directly formed on one surface side of the insulating substrate 3 by vapor deposition using a predetermined mask.

Even in such a configuration, the protruding portion 11 having a width W1 smaller than the width W2 of the submount 5 forms a solder relief portion between the submount 5 and the insulating substrate 3, and at the time of joining. Since the molten solder flows according to the shape of the protruding portion 11, it is possible to prevent the solder from spreading in the stacking direction of the laminated structure 7. Therefore, even when the stacking pitch of the semiconductor laser bar 4 is narrow, the occurrence of leakage due to soldering can be suppressed, and high integration of the semiconductor laser bar 4 in the laminated structure 7 can be realized. Further, the protruding portion 11 can be provided with a simple configuration, and the submount 5 and the conductor pattern 8 can be firmly joined at the joining portion P.
[Fourth Embodiment]

FIG. 6 is an enlarged cross-sectional view of a main part showing a joint portion between the submount of the semiconductor laser apparatus according to the fourth embodiment and the conductor pattern. As shown in the figure, in the fourth embodiment, the configuration of the joint portion P between the submount 5 and the conductor pattern 8 is further different from that in the first embodiment. Other configurations are the same as those in the first embodiment.

More specifically, in the fourth embodiment, the conductive member 12 provided in a protrusion shape on one surface side of the insulating substrate 3 and the protrusion 15 provided on one end surface 5a on the insulating substrate 3 side of the submount 5 , The protruding portion 11 is provided on both the conductor pattern 8 side and the submount 5 side. Similar to the first embodiment, the conductor pattern 8 is provided on the top of the conductive member 12, and the solder layer 13 is provided so as to cover the conductive member 12 and the conductor pattern 8.

Even in such a configuration, the protruding portion 11 having a width W1 smaller than the width W2 of the submount 5 forms a solder relief portion between the submount 5 and the insulating substrate 3, and at the time of joining. Since the molten solder flows according to the shape of the protruding portion 11, it is possible to prevent the solder from spreading in the stacking direction of the laminated structure 7. Therefore, even when the stacking pitch of the semiconductor laser bar 4 is narrow, the occurrence of leakage due to soldering can be suppressed, and high integration of the semiconductor laser bar 4 in the laminated structure 7 can be realized. Further, the protruding portion 11 can be provided with a simple configuration, and the submount 5 and the conductor pattern 8 can be firmly joined at the joining portion P. Further, by providing the protruding portions 11 on both the conductor pattern 8 side and the sub mount 5 side, a large relief portion for the solder can be secured. Therefore, leakage due to solder can be suppressed more reliably.
[Modification example]

The present invention is not limited to the above embodiment. For example, in the above embodiment, the center position of the protruding portion 11 with respect to the stacking direction coincides with the center position of the submount 5 with respect to the stacking direction, but the center position of the protruding portion 11 is relative to the center position of the submount 5. It may be shifted to one side. Further, for example, in the laminated structure 7, the configuration of the protruding portion 11 shown in FIG. 3 or FIG. 4 and the configuration of the protruding portion 11 shown in FIG. 5 may be provided alternately. In this case, since the position of the hem portion 13a of the solder layer 13 is reversed between the adjacent joint portions P, the occurrence of leakage due to the solder can be more preferably suppressed.

Further, in the above embodiment, the protruding portion 11 having a rectangular cross section is illustrated, but the cross-sectional shape of the protruding portion 11 is not limited to the rectangular shape, and may be another shape such as a triangular shape or a circular shape. When applying another cross-sectional shape, the maximum width of the protruding portion 11 with respect to the stacking direction may be smaller than the width of the submount 5 with respect to the stacking direction. Further, for example, when the protruding portion 11 having a trapezoidal cross section is adopted, it is preferable to form the protruding portion 11 so that the hem expands toward the insulating substrate 3 side. By doing so, it is possible to improve the heat dissipation from the submount 5 side to the insulating substrate 3 side.

When such a configuration is applied to the first embodiment, for example, as shown in FIG. 7, a conductive member 12 having a trapezoidal cross section that widens toward the insulating substrate 3 side is placed on one surface side of the insulating substrate 3. The solder layer 13 may be provided so as to cover the conductive member 12 and the conductor pattern 8. Although not shown, when applied to the second embodiment, the convex portion 14 of the concave-convex surface 3a of the insulating substrate 3 is provided in a trapezoidal cross-section that widens toward the insulating substrate 3, and the conductive member 12 and the conductor pattern. The solder layer 13 may be provided so as to cover 8.

Further, when applied to the third embodiment, as shown in FIG. 8, a protrusion 15 having a trapezoidal cross section that widens toward the insulating substrate 3 side is provided on one end surface 5a of the submount 5, and the protrusion 15 is provided. The solder layer 13 may be provided so as to cover the above. Although not shown, when applied to the fourth embodiment, the width of the top surface of the protrusion 15 on the one end surface 5a side of the submount 5 and the width of the top surface of the conductive member 12 are substantially matched, and the protrusion 15 and the conductive member 12 are conductive. The projecting portion 11 having a trapezoidal cross section that expands toward the insulating substrate 3 side when combined with the member 12 may be formed.

1 ... Semiconductor laser device, 3 ... Insulated substrate, 3a ... Concavo-convex surface, 4 ... Semiconductor laser bar (semiconductor laser element), 5 ... Submount, 6 ... Laser unit, 7 ... Laminated structure, 8 ... Conductor pattern, 11 ... Projection Part, 12 ... Conductive member, 13 ... Solder layer (solder), 14 ... Convex part, 15 ... Projection, P ... Joint part, W1 ... Protruding part width, W2 ... Submount width.

Claims (7)

A heat-conducting insulating substrate with a conductor pattern formed on one side,
It has a laminated structure in which a laser unit in which a semiconductor laser element is fixed to a submount is laminated.
The laminated structure is arranged on the one side of the insulating substrate so that the laminating direction of the laser unit is the in-plane direction of the insulating substrate .
The least one of the previous SL submount and the conductor pattern is provided with a projecting portion projecting toward the other party,
The width of the protruding portion with respect to the stacking direction is smaller than the width of the submount with respect to the stacking direction.
Wherein the sub-mount and the conductor pattern, thus joined together the solder covering the projecting portion,
Spaces serving as escape portions for the solder are formed on both sides of the protruding portion in the stacking direction by the flat surface of the submount and the flat surface of the insulating substrate.
A semiconductor laser device in which the hem of the solder covering the protruding portion is located in a range not protruding from the submount in the stacking direction when viewed from the normal direction of the insulating substrate. The semiconductor laser device according to claim 1, wherein the laser unit is a semiconductor laser device in which the semiconductor laser element is fixed only on one surface side of the submount. The semiconductor laser device according to claim 1 or 2, wherein the protruding portion is provided on the conductor pattern side by a conductive member provided in a protruding shape on the one surface side of the insulating substrate. One side of the insulating substrate is an uneven surface.
The semiconductor laser device according to claim 1 or 2, wherein the protruding portion is provided on the conductor pattern side by a convex portion of the uneven surface. The semiconductor laser device according to claim 1 or 2, wherein the protruding portion is provided on the submount side by a protrusion provided on the end portion of the submount on the insulating substrate side. The protruding portion is formed on the conductor pattern side and the submount by a conductive member provided in a protrusion shape on the one surface side of the insulating substrate and a protrusion provided on an end portion of the submount on the insulating substrate side. The semiconductor laser device according to claim 1 or 2, which is provided on both sides. The semiconductor laser device according to any one of claims 1 to 6, wherein the protruding portion has a trapezoidal cross section so as to widen the hem toward the insulating substrate side.

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