JP2010153710A - Semiconductor laser device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device capable of easily reducing an electric resistance between an electrode layer and an active layer. <P>SOLUTION: This semiconductor laser device 100 includes: a purple-blue color semiconductor laser element 50 containing a front surface 50a; a GaAs substrate 71 having a step portion 80; a p side pad electrode 77 formed at an opposite side of the GaAs substrate 71; and an active layer 73 formed between the GaAs substrate 71 and the p side pad electrode 77, wherein there is also provided a red semiconductor laser element 70 in which a lower surface of the p side pad electrode 77 is bonded to the front surface 50a of the purple-blue color semiconductor laser element 50. The red semiconductor laser element 70 includes an n side ohmic electrode 78 formed on a bottom face 80b of the step portion 80 extending toward the purple-blue color semiconductor laser element 50 side from a front surface 71a (80c) of the GaAs substrate 71. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device and a manufacturing method thereof, and more particularly to an integrated semiconductor laser device in which a plurality of semiconductor laser elements are joined and a manufacturing method thereof.

  Conventionally, in a CD (compact disc) / CD-R (compact disc-recordable) drive, an infrared semiconductor laser element having a wavelength of about 780 nm has been used as a light source. In a DVD (digital versatile disc) drive, a red semiconductor laser element having a wavelength of about 650 nm has been used as a light source.

  On the other hand, in recent years, a DVD that can be recorded / reproduced using blue-violet light has been developed. For such DVD recording / reproduction, a blue DVD drive using a blue-violet semiconductor laser element having a wavelength of about 405 nm is being developed at the same time. This DVD drive requires compatibility with conventional CD / CD-R and DVD.

  In this case, a method of providing a plurality of optical disk pickups for individually emitting infrared light, red light and blue-violet light in a DVD drive, or infrared, red and blue-violet semiconductor laser elements individually in one optical disk pickup The compatibility with conventional CDs, DVDs, and recordable / reproducible DVDs can be realized by the method of providing them. However, this method causes an increase in the number of parts, which makes it difficult to reduce the size of the pickup device, simplify the configuration, and reduce the price.

  In order to suppress such an increase in the number of components, conventionally, a two-wavelength semiconductor laser element in which an infrared laser and a red laser are integrated on one chip has been put into practical use. On the other hand, since the blue-violet laser is not formed on a GaAs substrate or the like, it is very difficult to make the blue-violet semiconductor laser element into one chip together with the infrared and red semiconductor laser elements.

  Therefore, conventionally, an integrated semiconductor laser element in which a red semiconductor laser element and an infrared semiconductor laser element are joined to a blue-violet semiconductor laser element has been proposed (see, for example, Patent Document 1).

  Patent Document 1 discloses an integrated semiconductor laser element in which a red semiconductor laser element and an infrared semiconductor laser element are bonded to the upper and lower surfaces of a blue-violet semiconductor laser element, respectively. In the integrated semiconductor laser element described in Patent Document 1, a convex portion is provided on the surface of one of the two semiconductor laser elements to be joined (for example, a blue-violet semiconductor laser element and a red semiconductor laser element), and Since the surface of the other laser element is provided with a recess, the protrusion of one laser element is fitted into the recess of the other laser element and joined in a state of alignment. A substrate having a substantially uniform thickness and an electrode layer (n-side electrode) are provided on the flat surface of the substrate on the opposite side to the bonding surface of the two laser elements to be bonded.

JP 2006-93379 A

  However, in the integrated semiconductor laser element disclosed in Patent Document 1, a substrate having a substantially uniform thickness is provided on the side opposite to the bonding surface of the two laser elements to be bonded. It is considered that the distance from the active layer to the active layer inside the laser element increases as much as the uniform thickness (maximum thickness) of the substrate is added in addition to the thickness of the semiconductor layer. For this reason, there exists a problem that it is difficult to reduce the electrical resistance which arises between an electrode layer and an active layer.

  The present invention has been made to solve the above-described problems, and one object of the present invention is a semiconductor laser device capable of easily reducing the electrical resistance between an electrode layer and an active layer, and a semiconductor laser device thereof It is to provide a manufacturing method.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, a semiconductor laser device according to a first aspect of the present invention is formed on a first semiconductor laser element including a first surface, a second surface having a stepped portion, and an opposite side of the second surface. And a second semiconductor laser element including a second semiconductor laser element including a third surface formed and an active layer formed between the second surface and the third surface, the third surface being joined to the first surface. The laser element further includes an electrode layer formed on at least one of a side surface or a bottom surface of the stepped portion extending from the second surface toward the first semiconductor laser element side.

  In the semiconductor laser device according to the first aspect of the present invention, as described above, the second semiconductor laser element is on at least one of the side surface or the bottom surface of the stepped portion extending from the second surface toward the first semiconductor laser element. The distance (thickness) from the electrode layer formed on at least one of the side surface or the bottom surface of the stepped portion to the active layer is set to a value other than the electrode layer of the second semiconductor laser element. Since the distance (thickness) from the surface to the active layer can be made smaller, the electrical resistance between the electrode layer and the active layer in the second semiconductor laser element can be easily reduced.

  In the semiconductor laser device according to the first aspect, preferably, the second semiconductor laser element is formed on the first surface of the active layer and on the third surface of the active layer. And a second conductivity type semiconductor layer. If comprised in this way, since the 2nd semiconductor laser element laminated | stacked in order of the 2nd conductivity type semiconductor layer, the active layer, and the 1st conductivity type semiconductor layer is joined on the 1st surface of a 1st semiconductor laser element. The laser beam emission point from the first semiconductor laser element and the laser beam emission point from the second semiconductor laser element can be brought close to each other.

  According to a second aspect of the present invention, there is provided a method for manufacturing a semiconductor laser device, comprising: a step of forming a first semiconductor laser element including a first surface; and a second step provided on the growth substrate side on the surface of the growth substrate. Forming a second semiconductor laser element including a surface, a third surface provided on the side opposite to the second surface, and an active layer provided on the third surface side of the growth substrate; Bonding the first surface to the first surface, and forming the second semiconductor laser element includes: forming a stepped portion extending from the second surface toward the first semiconductor laser element side; Forming an electrode layer on at least one of the bottom surfaces.

  In the semiconductor laser device manufacturing method according to the second aspect of the present invention, as described above, the step of forming the second semiconductor laser element forms a stepped portion extending from the second surface toward the first semiconductor laser element side. And an active layer from the electrode layer formed on at least one of the side surface or the bottom surface of the step portion by including the step of forming an electrode layer on at least one of the side surface or the bottom surface of the step portion. Can be made smaller than the distance from the surface other than the electrode layer of the second semiconductor laser element to the active layer. Thereby, a semiconductor laser device including the second semiconductor laser element in which the electrical resistance between the electrode layer and the active layer is reduced can be easily obtained.

  In the method of manufacturing the semiconductor laser device according to the second embodiment, preferably, after the bonding step, the growth substrate is removed or the thickness of the growth substrate is reduced with the electrode layer remaining. The method further includes a step. According to this structure, the second semiconductor laser element bonded to the first semiconductor laser element has the growth substrate removed or thinned, so that the cleavage and element division during the resonator end face formation can be performed. It can be done easily.

  In this case, preferably, the step portion is formed such that the plurality of step portions are separated from each other in an island shape. If comprised in this way, since the several level | step-difference part recessed toward the active layer from the surface of a growth board | substrate will be formed in an island shape in a growth board | substrate, the thick part of a growth board | substrate (a level | step difference part is formed) The portion that has not been left is left in a lattice shape in the second semiconductor laser element before bonding. Therefore, the second semiconductor laser element can be bonded to the first semiconductor laser element while maintaining the strength of the second semiconductor laser element even in the state having a plurality of step portions.

  In the method of manufacturing a semiconductor laser device according to the second aspect, preferably, the step of forming the second semiconductor laser element includes forming an electrode layer prior to the step of bonding the second semiconductor laser element to the first semiconductor laser element. Including the step of alloying. If comprised in this way, on the manufacturing process, it heat-processes for alloying of the electrode layer formed in the 2nd semiconductor laser element before a joining process, Then, the 2nd semiconductor laser element after heat processing is carried out. A semiconductor laser device may be formed by bonding to the first semiconductor laser element. That is, when the second semiconductor laser element is subjected to the heat treatment after the second semiconductor laser element before the heat treatment is bonded to the first semiconductor laser element, the treatment temperature in the heat treatment step is the first temperature of the first semiconductor laser element. While there is an inconvenience that the ohmic characteristics are likely to be deteriorated by adversely affecting the ohmic electrode layer formed on the surface side, in the above configuration, the heat-treated second semiconductor laser element is bonded to the first semiconductor laser element. Thus, the electrode layer of the first semiconductor laser element is not affected by the heat treatment (alloying). Thereby, it can suppress that the characteristic of the ohmic electrode layer of a 1st semiconductor laser element deteriorates.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view for explaining a schematic structure of a semiconductor laser device of the present invention. 2 to 6 are diagrams for explaining a schematic manufacturing process of the semiconductor laser device shown in FIG. First, with reference to FIG. 1, before explaining a specific embodiment of the present invention, a schematic structure of a semiconductor laser device 40 according to the present invention will be described.

  As shown in FIG. 1, the semiconductor laser device 40 of the present invention includes a first semiconductor laser element 10 and a second semiconductor laser element 20 bonded on the surface 10 a of the first semiconductor laser element 10. The surface 10a is an example of the “first surface” in the present invention.

  The first semiconductor laser element 10 has a structure in which a first conductive semiconductor layer 1, an active layer 2, and a second conductive semiconductor layer 3 are sequentially stacked. The active layer 2 has a single layer, a single quantum well (SQW) structure, or a multiple quantum well (MQW) structure.

  The first conductivity type semiconductor layer 1 is composed of a first conductivity type cladding layer having a band gap larger than that of the active layer 2. Moreover, you may have the light guide layer which has the band gap between the 1st conductivity type semiconductor layer 1 and the active layer 2 in the active layer 2 side of the 1st conductivity type semiconductor layer 1. FIG. Further, a carrier block layer having a band gap larger than that of the first conductivity type semiconductor layer 1 may be provided between the first conductivity type semiconductor layer 1 and the active layer 2. Moreover, you may have a 1st conductivity type contact layer on the opposite side to the active layer 2 of the 1st conductivity type semiconductor layer 1. FIG.

  The second conductivity type semiconductor layer 3 is composed of a second conductivity type cladding layer having a band gap larger than that of the active layer 2. Further, an optical guide layer having a band gap between the second conductive semiconductor layer 3 and the active layer 2 may be provided on the active layer 2 side of the second conductive semiconductor layer 3. Further, a carrier block layer having a band gap larger than that of the second conductivity type semiconductor layer 3 may be provided between the second conductivity type semiconductor layer 3 and the active layer 2. Moreover, you may have a 2nd conductivity type contact layer in the opposite side to the active layer 2 of the 2nd conductivity type semiconductor layer 3. FIG. In this case, the second conductivity type contact layer preferably has a smaller band gap than the second conductivity type semiconductor layer 3 (second conductivity type cladding layer).

  Each semiconductor layer (first conductive type semiconductor layer 1, active layer 2 and second conductive type semiconductor layer 3) is an AlGaAs-based, GaInAs-based, AlGaInP-based, AlGaInNAs-based, AlGaSb-based, GaInAsP-based, or nitride-based semiconductor. MgZnSSe series, ZnO series and the like. As the nitride semiconductor, GaN, AlN, InN, BN, TlN, or a mixed crystal thereof can be used.

  Further, the substrate opposite to the active layer 2 of the first conductivity type semiconductor layer 1 may be a substrate. When each semiconductor layer is formed of a nitride semiconductor having a wurtzite structure, the substrate may be a first conductivity type nitride semiconductor substrate or a heterogeneous substrate. Examples of the heterogeneous substrate include a first conductivity type α-SiC substrate having a hexagonal structure and a rhombohedral structure, a first conductivity type GaAs substrate, a first conductivity type GaP substrate, a first conductivity type InP substrate, and a first conductivity type Si substrate. Can be used. The first conductivity type semiconductor layer 1 may include a substrate. However, in order to obtain an AlGaInN semiconductor layer having the best crystallinity, it is most preferable to use a nitride semiconductor substrate.

  The plane orientation of the growth surface of the nitride-based semiconductor substrate is a nonpolar plane such as the (0001) plane and the (000-1) plane, the (11-20) plane and the (1-100) plane, or (11-22 ) Plane, (11-2-2) plane, (1-101) plane and (1-10-1) plane can be used.

Alternatively, the first conductive side electrode 4 may be formed on the surface of the first conductive type semiconductor layer 1 opposite to the active layer 2. Further, an insulating substrate may be included on the surface of the first conductivity type semiconductor layer 1 opposite to the active layer 2. In this case, a sapphire substrate, a spinel substrate, a LiAlO ₃ substrate, or the like can be used. Further, a structure for confining the current flowing through the active layer 2 is formed in the vicinity of the active layer 2. In this example, an insulating film 5 having an opening 5 a is formed on the surface of the second conductivity type semiconductor layer 3. Further, the second conductive side electrode 6 is formed on the surface of the second conductive type semiconductor layer 3 in the opening 5a.

  The second semiconductor laser element 20 has a structure in which a first conductivity type semiconductor layer 21, an active layer 22, and a second conductivity type semiconductor layer 23 are sequentially stacked. The active layer 22 has a single layer, an SQW structure, or an MQW structure.

  The first conductivity type semiconductor layer 21 is composed of a first conductivity type cladding layer having a band gap larger than that of the active layer 22. Further, a light guide layer having a band gap between the first conductive semiconductor layer 21 and the active layer 22 may be provided on the active layer 22 side of the first conductive semiconductor layer 21. Further, a carrier block layer having a band gap larger than that of the first conductivity type semiconductor layer 21 may be provided between the first conductivity type semiconductor layer 21 and the active layer 22. Moreover, you may have a 1st conductivity type contact layer in the opposite side to the active layer 22 of the 1st conductivity type semiconductor layer 21. FIG.

  The second conductivity type semiconductor layer 23 is composed of a second conductivity type cladding layer having a band gap larger than that of the active layer 22. Further, an optical guide layer having a band gap between the second conductive semiconductor layer 23 and the active layer 22 may be provided on the active layer 22 side of the second conductive semiconductor layer 23. Further, a carrier block layer having a band gap larger than that of the second conductivity type semiconductor layer 23 may be provided between the second conductivity type semiconductor layer 23 and the active layer 22. In addition, a second conductivity type contact layer may be provided on the opposite side of the second conductivity type semiconductor layer 23 from the active layer 22. In this case, the second conductivity type contact layer preferably has a smaller band gap than the second conductivity type semiconductor layer 23 (second conductivity type cladding layer).

  Each semiconductor layer (first conductive semiconductor layer 21, active layer 22 and second conductive semiconductor layer 23) is made of AlGaAs, GaInAs, AlGaInP, AlGaInNAs, AlGaSb, GaInAsP, MgZnSSe, and ZnO. It consists of systems.

  The opposite side of the first conductive semiconductor layer 21 from the active layer 22 may be a substrate, or the first conductive semiconductor layer 21 may include a substrate.

  Here, in this invention, as shown in FIG. 1, the recessed part 30 is formed in the surface 21a side of the 1st conductivity type semiconductor layer 21. As shown in FIG. The recess 30 is formed such that the inclined side surface 30 a extends from the surface 21 a of the first conductive semiconductor layer 21 toward the active layer 22, and the bottom surface 30 b is located inside the first conductive semiconductor layer 21. ing. The first conductive side electrode 24 is formed on the side surface 30 a and the bottom surface 30 b of the recess 30. Therefore, the distance from the first conductive side electrode 24 on the bottom surface 30 b to the active layer 22 is configured to be smaller than the distance from the surface other than the recess 30 of the first conductive type semiconductor layer 21 to the active layer 22. The surface 21a, the concave portion 30, and the first conductive side electrode 24 are examples of the “second surface”, “stepped portion”, and “electrode layer” in the present invention, respectively.

  Further, a structure for confining the current flowing through the active layer 22 is formed in the vicinity of the active layer 22. In this example, an insulating film 25 having an opening 25 a is formed on the lower surface of the second conductivity type semiconductor layer 23. As shown in FIG. 1, the opening 25 a is preferably formed in the vicinity of a position facing the bottom surface 30 a of the recess 30. A second conductive side electrode 26 is formed on the second conductive type semiconductor layer 23 in the opening 25a. The C1 side surface (lower surface) of the second conductive side electrode 26 is joined to the surface 10 a of the first semiconductor laser element 10. The surface of the second conductive side electrode 26 is an example of the “third surface” in the present invention.

In addition, a low-reflectivity dielectric multilayer film is formed on the cavity facets of the first semiconductor laser element 10 and the second semiconductor laser element 20 on the laser beam emission side. Also, a dielectric multilayer film having a high reflectivity is formed on the end face of the resonator on the laser beam reflection side. Here, as the dielectric multilayer film, GaN, AlN, BN, Al ₂ O ₃ , SiO ₂ , ZrO ₂ , HfO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ , La ₂ O ₃ , SiN, AlON and MgF ₂ or a multilayer film made of Ti ₃ O ₅ , Nb ₂ O _3, or the like, which are materials having different mixing ratios.

  Next, a schematic manufacturing process of the semiconductor laser device 40 of the present invention will be described with reference to FIGS.

  First, as shown in FIG. 2, a semiconductor element layer 10 b composed of the first conductive semiconductor layer 1, the active layer 2, and the second conductive semiconductor layer 3 is formed, and on the surface of the second conductive semiconductor layer 3. An insulating film 5 having an opening 5a is formed. Then, the second conductive side electrode 6 is formed so as to cover the opening 5a and the insulating film 5 in the vicinity of the opening 5a. Thereby, a wafer of the first semiconductor laser element 10 excluding the first conductive side electrode 4 is formed.

  Next, as shown in FIG. 3, a semiconductor element layer 20 a composed of the first conductivity type semiconductor layer 21, the active layer 22 and the second conductivity type semiconductor layer 23 is formed, and on the surface of the second conductivity type semiconductor layer 23. An insulating film 25 having an opening 25a is formed. Then, the second conductive side electrode 26 is formed so as to cover the opening 25a and the insulating film 25 in the vicinity of the opening 25a.

  Thereafter, as shown in FIG. 4, a recess 30 is formed on the surface 21 a side of the first conductivity type semiconductor layer 21 using dry etching or wet etching. Thereafter, the first conductive side electrode 24 is formed so as to cover the side surface 30 a and the bottom surface 30 b of the recess 30. Thereafter, in order to alloy the first conductive semiconductor layer 21 and the first conductive side electrode 24, heat treatment is performed in a nitrogen atmosphere. Thereby, a wafer before bonding of the second semiconductor laser element 20 is formed.

  After that, as shown in FIG. 5, the surface (lower surface) of the second conductive side electrode 26 of the second semiconductor laser element 20 and the insulating film 5 on the surface 10a side of the first semiconductor laser element 10 are opposed to each other. Join. Subsequently, as shown in FIG. 6, the surface 21 a (upper surface) of the first conductivity type semiconductor layer 21 is polished or etched to reduce the thickness of the first conductivity type semiconductor layer 21 of the second semiconductor laser element 20. . For etching, wet etching or dry etching is used.

  Thereafter, the first conductive side electrode 4 is formed on the lower surface of the first conductive type semiconductor layer 1 of the first semiconductor laser element 10. Further, a part of the semiconductor element layer 20a is removed at the separation position of the second semiconductor laser element 20 shown in FIG. 5 so that the recess 30 remains, so that the resonator extends (in the direction perpendicular to the plane of FIG. 6). The second semiconductor laser element 20 having a predetermined width in the B direction orthogonal to the first direction is formed. Here, unnecessary portions of the semiconductor element layer 20a may be separated by scribing the second semiconductor laser element 20 in the direction of the resonator, or unnecessary portions may be removed by wet etching or dry etching. Good.

  Thereafter, the wafer of the first semiconductor laser element 10 is cleaved in a bar shape so as to have a predetermined resonator length, and the resonator end faces of the first semiconductor laser element 10 and the second semiconductor laser element 20 are formed. Thereafter, a low-reflectance dielectric multilayer film is formed on the light emitting side resonator end faces of the first semiconductor laser element 10 and the second semiconductor laser element 20, and a high reflectivity dielectric is formed on the light reflecting side resonator end faces. A body multilayer film is formed. Finally, a plurality of chips of the semiconductor laser device 40 (see FIG. 1) are formed by dividing the bar along the resonator direction at the element dividing position of FIG.

  In the present invention, as described above, the second semiconductor laser element 20 is formed on the bottom surface 30b of the recess 30 extending from the surface 21a of the first conductivity type semiconductor layer 21 toward the first semiconductor laser element 10 side. By including the first conductive side electrode 24, the distance (thickness) from the first conductive side electrode 24 to the active layer 22 is made larger than the distance (thickness) from the surface 21 a of the first conductive type semiconductor layer 21 to the active layer 22. Since it can be reduced, the electrical resistance between the first conductive side electrode 24 and the active layer 22 in the second semiconductor laser element 20 can be easily reduced. Thereby, since the operating voltage of the second semiconductor laser element 20 is reduced, the heat generation of the semiconductor laser device 40 can be suppressed.

  In the present invention, the second semiconductor laser element 20 includes the first conductive semiconductor layer 21 formed on the surface 21 a side of the active layer 22 and the second conductive semiconductor layer formed on the lower surface side of the active layer 22. 23, the second semiconductor laser element 20 in which the second conductive semiconductor layer 23, the active layer 22, and the first conductive semiconductor layer 21 are stacked in this order on the surface 10a side of the first semiconductor laser element 10 is provided. Since the bonding is performed, the emission point of the laser beam from the first semiconductor laser element 10 and the emission point of the laser beam from the second semiconductor laser element 20 can be brought close to each other. When the first conductive semiconductor layer 21 includes a substrate on the surface 21a side, or when the substrate is formed on the surface 21a side of the first conductive type semiconductor layer 21, the first semiconductor laser element 10 and the second semiconductor After bonding the laser element 20, only the substrate can be easily removed or thinned without removing the laser element structure.

  In the present invention, the recess 30 is formed on the bottom surface 30 b of the recess 30 by forming the side surface 30 a so as to extend from the surface 21 a of the first conductivity type semiconductor layer 21 toward the first semiconductor laser element 10 side. The first conductive side electrode 24 can be easily brought close to the active layer 22.

  In the present invention, when the first conductive type semiconductor layer 21 of the second semiconductor laser element 20 is made of a III-V group semiconductor containing at least one of P, As, and Sb, the first conductive type semiconductor layer 21 By alloying the first conductive side electrode 24, the ohmic characteristics between the first conductive type semiconductor layer 21 and the first conductive side electrode 24 can be improved, and the contact resistance can be further reduced.

  Further, in the manufacturing process of the present invention, as described above, the step of forming the second semiconductor laser element 20 includes the recess 30 extending from the surface 21a of the first conductivity type semiconductor layer 21 toward the first semiconductor laser element 10 side. And the step of forming the first conductive side electrode 24 on the side surface 30a and the bottom surface 30b of the recess 30 to thereby form the first conductive side electrode formed on the side surface 30a and the bottom surface 30b of the recess 30. The distance from 24 to the active layer 22 can be made smaller than the distance from the surface 21 a other than the first conductive side electrode 24 of the second semiconductor laser element 20 to the active layer 22. Thereby, the semiconductor laser device 40 including the second semiconductor laser element 20 in which the electrical resistance between the first conductive side electrode 24 and the active layer 22 is reduced can be easily obtained.

  In the manufacturing process of the present invention, the first conductive side electrode 24 is left after the step of bonding the wafer on which the second semiconductor laser element 20 is formed to the wafer on which the first semiconductor laser element 10 is formed. By providing a step of reducing the thickness of the first conductive semiconductor layer 21, the wafer of the second semiconductor laser element 20 after bonding has the first conductive semiconductor layer 21 thinned. Cleaving at the time of end face formation can be performed easily. When the first conductive semiconductor layer 21 is formed on a substrate (growth substrate) or when the first conductive semiconductor layer 21 includes a substrate (growth substrate), after the bonding step, The substrate (growth substrate) may be removed with the first conductive side electrode 24 left. Also in this case, since the substrate (growth substrate) is removed from the second semiconductor laser element 20 after being bonded to the first semiconductor laser element 10, cleavage and element division at the time of resonator end face formation are facilitated. It can be carried out.

  Further, in the manufacturing process of the present invention, the step of forming the second semiconductor laser element 20 is preceded by the step of bonding the second semiconductor laser element 20 in the wafer state to the first semiconductor laser element 10. 24 and the step of alloying the first conductive type semiconductor layer 21 by heat treatment, the alloying of the first conductive side electrode 24 formed on the second semiconductor laser element 20 before the bonding step in the manufacturing process is performed. Heat treatment (alloying step under a temperature condition of about 500 ° C.) is performed, and then the heat-treated second semiconductor laser element 20 is joined to the first semiconductor laser element 10, and the semiconductor laser device 40 is assembled. What is necessary is just to form. That is, when the second semiconductor laser element 20 is subjected to the heat treatment after the second semiconductor laser element 20 before the heat treatment is bonded to the first semiconductor laser element 10, the treatment temperature (about 500 ° C.) in the heat treatment step is On the other hand, there is a disadvantage that the ohmic characteristics are easily deteriorated by adversely affecting the ohmic electrode layer (second conductive side electrode 6) formed on the surface 10a side of the first semiconductor laser element 10, and in the above configuration, the heat treatment is completed. By bonding the second semiconductor laser element 20 to the first semiconductor laser element 10, the electrode layer (the first conductive side electrode 4 and the second conductive side electrode 6) of the first semiconductor laser element 10 is subjected to heat treatment (alloying). ) Is not affected. Thereby, it can suppress that the characteristic of the ohmic electrode layer of the 1st semiconductor laser element 10 deteriorates. Furthermore, by including the above steps, the multilayered metal layer is alloyed immediately after the formation of the first conductive side electrode 24 before joining the second semiconductor laser element 20 to the first semiconductor laser element 10. The ohmic characteristics at the contact interface between the first conductive type semiconductor layer 21 and the first conductive side electrode 24 can be improved.

  In the manufacturing process of the present invention, the second semiconductor laser element 20 including the first conductive type semiconductor layer 21 having the surface 21a, the active layer 22, and the second conductive type semiconductor layer 23 is formed. Since the second semiconductor laser element 20 in which the second conductive type semiconductor layer 23, the active layer 22 and the first conductive type semiconductor layer 21 are stacked in this order is joined to the surface 10a side of the first semiconductor laser element 10, the first semiconductor The semiconductor laser device 40 in which the laser beam emission point from the laser element 10 and the laser beam emission point from the second semiconductor laser element 20 are close to each other can be obtained. When the first conductive semiconductor layer 21 includes a substrate on the surface 21a side, or when the substrate is formed on the surface 21a side of the first conductive type semiconductor layer 21, the first semiconductor laser element 10 and the second semiconductor After the laser element 20 is bonded, the semiconductor laser device 40 can be obtained by easily removing or thinning only the substrate without removing the laser element structure.

  In the manufacturing process of the present invention, when the second semiconductor laser element 20 is formed by the first conductive semiconductor layer 21 made of a group III-V semiconductor containing at least one of P, As, and Sb, the first conductive type By alloying the semiconductor layer 21 and the first conductive side electrode 24, the ohmic characteristics between the first conductive type semiconductor layer 21 and the first conductive side electrode 24 can be improved, and the contact resistance can be further reduced. .

(First embodiment)
7 and 8 are a sectional view and a plan view, respectively, showing the structure of the semiconductor laser device according to the first embodiment of the present invention. First, the structure of the semiconductor laser device 100 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 8 shows a cross section taken along line 1000-1000 in FIG.

  As shown in FIG. 7, the semiconductor laser device 100 according to the first embodiment includes a red semiconductor laser element 70 having an oscillation wavelength of about 650 nm on a surface 50a of a blue-violet semiconductor laser element 50 having an oscillation wavelength of about 405 nm. , And an infrared semiconductor laser element 90 having an oscillation wavelength of about 780 nm. The blue-violet semiconductor laser element 50 is an example of the “first semiconductor laser element” in the present invention, and the red semiconductor laser element 70 and the infrared semiconductor laser element 90 are the “second semiconductor laser element” in the present invention. The surface 50a is an example of the “first surface” in the present invention.

As shown in FIG. 7, the blue-violet semiconductor laser device 50 has a Si-doped n-type Al _0.05 Ga _0.95 on the upper surface of an n-type GaN substrate 51 having a width of about 400 μm and a thickness of about 100 μm. An n-type cladding layer 52 made of N, an active layer 53 having an MQW structure in which quantum well layers made of InGaN with a high In composition and barrier layers made of InGaN with a low In composition are alternately stacked, and an Mg-doped p-type A p-type cladding layer 54 made of Al _0.05 Ga _0.95 N is formed.

  As shown in FIG. 7, the p-type cladding layer 54 has a convex portion formed at a substantially central portion of the element and flat portions extending on both sides (B direction) of the convex portion. In addition, a p-side ohmic electrode layer 55 including a Pd layer, a Pt layer, and an Au layer is formed on the convex portion of the p-type cladding layer 54 in order from the p-type cladding layer 54. A ridge 56 for forming an optical waveguide is formed by the convex portion of the p-type cladding layer 54 and the p-side ohmic electrode layer 55. The ridge 56 has a width of about 1.5 μm in the B direction and is formed so as to extend along the resonator direction (A direction in FIG. 8).

A current blocking layer 57 made of SiO ₂ is formed so as to cover the upper surface of the flat portion of the p-type cladding layer 54 and the side surface of the ridge 56. A p-side pad electrode 58 made of an Au layer or the like is formed so as to cover the upper surfaces of the ridge 56 and the current blocking layer 57.

  Further, as shown in FIGS. 7 and 8, a pad electrode 60a made of Au or the like is formed on the upper surface of the current blocking layer 57 on the B1 side of the ridge 56. A pad electrode 60b made of Au or the like is formed on the upper surface of the current blocking layer 57 on the B2 side of the ridge 56. The pad electrodes 60 a and 60 b are formed to extend along the resonator direction of the blue-violet semiconductor laser device 50. Thus, the red semiconductor laser element 70 is bonded to the blue-violet semiconductor laser element 50 at the position where the pad electrode 60a is provided, and the infrared semiconductor laser element 90 is blue-violet at the position where the pad electrode 60b is provided. Bonded to the semiconductor laser element 50.

  In addition, an n-side electrode 59 made of a Pt layer, a Pd layer, and an Au layer is formed on the lower surface of the n-type GaN substrate 51 in the order closer to the n-type GaN substrate 51.

  Further, as shown in FIG. 7, the red semiconductor laser device 70 includes an n-type cladding layer 72 made of AlGaInP having a thickness of about 2 μm on a lower surface of an n-type GaAs substrate 71 having a thickness of about 60 μm, and GaInP. An active layer 73 having an MQW structure in which quantum well layers made of Al and barrier layers made of AlGaInP are alternately stacked, and a p-type cladding layer 74 made of AlGaInP having a thickness of about 1 μm are formed. The n-type cladding layer 72 and the p-type cladding layer 74 are examples of the “first conductivity type semiconductor layer” and the “second conductivity type semiconductor layer” of the present invention, respectively.

  Further, the p-type cladding layer 74 has a convex portion formed at a position slightly shifted from the substantially central portion of the element to the B2 side, and a flat portion extending on both sides (B direction) of the convex portion. A ridge 75 for forming an optical waveguide is formed by the convex portion of the p-type cladding layer 74. The ridge 75 has a width of about 2 μm in the B direction and is formed so as to extend along the resonator direction (A direction in FIG. 8).

Further, a current blocking layer 76 made of SiO _{2 is provided} on the lower surface of the p-type cladding layer 74 other than the ridge 75 and so as to cover the active layer 73, the n-type cladding layer 72 and the side surface of the GaAs substrate 71 from the p-type cladding layer 74. Is formed. Further, a p-side pad in which a Cr layer having a thickness of about 10 nm and an Au layer having a thickness of about 2.2 μm are laminated so as to cover the lower surfaces of the ridge 75 (p-type cladding layer 74) and the current blocking layer 76. An electrode 77 is formed.

  Here, in the first embodiment, as shown in FIG. 7, a stepped portion 80 is formed on the surface 71 a of the GaAs substrate 71. The stepped portion 80 includes a bottom surface 80b formed on the B1 side of the GaAs substrate 71 (the left end side of the blue-violet semiconductor laser device 50) and a B2 side of the GaAs substrate 71 (the waveguide side of the blue-violet semiconductor laser device 50). The upper surface 80c (surface 71a) formed on the upper surface 80c and the side surface 80a extending from the upper surface 80c toward the active layer 73 in an inclined manner. Here, an obtuse ridge is formed by the upper surface 80c and the side surface 80a. The bottom surface 80b is exposed on the outer surface of the red semiconductor laser element 70 on the B1 side. The thickness from the bottom surface 80b to the lower surface of the GaAs substrate 71 is about 30 μm. The GaAs substrate 71 and the surface 71a are examples of the “growth substrate” and the “second surface” in the present invention, respectively.

  Further, an n-side ohmic electrode 78 is formed on the bottom surface 80b of the stepped portion 80, in which an AuGe layer and an Ni layer are stacked in this order from the lower layer to the upper layer. Further, the end portion on the B2 side of the n-side ohmic electrode 78 is in contact with the side surface 80a. A pad electrode 79 made of an Au layer is formed on the upper surface of the n-side ohmic electrode 78 and on a part of the side surface 80a of the stepped portion 80. Therefore, in the red semiconductor laser element 70, the distance (thickness) from the n-side ohmic electrode 78 to the active layer 73 is configured to be smaller than the distance (thickness) from the upper surface of the GaAs substrate 71 to the active layer 73. The n-side ohmic electrode 78 is an example of the “electrode layer” in the present invention.

  In the red semiconductor laser element 70, the lower surface of the p-side pad electrode 77 and the upper surface of the pad electrode 60 a are bonded via the conductive adhesive layer 9. The lower surface of the p-side pad electrode 77 is an example of the “third surface” in the present invention.

  Further, as shown in FIG. 7, the infrared semiconductor laser device 90 includes an n-type cladding layer 92 made of AlGaAs having a thickness of about 2 μm on the lower surface of a GaAs substrate 91 having a thickness of about 60 μm, and an Al composition. An active layer 93 having an MQW structure in which quantum well layers made of low AlGaAs and barrier layers made of AlGaAs having a high Al composition are alternately stacked, and a p-type cladding layer 94 made of AlGaAs having a thickness of about 1 μm. Is formed. The n-type cladding layer 92 and the p-type cladding layer 94 are examples of the “first conductivity type semiconductor layer” and the “second conductivity type semiconductor layer” of the present invention, respectively.

  The p-type cladding layer 94 has a convex portion formed at a position slightly shifted from the substantially central portion of the element to the B1 side, and a flat portion extending on both sides (B direction) of the convex portion. A ridge 95 for forming an optical waveguide is formed by the convex portion of the p-type cladding layer 94. The ridge 95 has a width of about 3 μm in the B direction and is formed to extend along the resonator direction (A direction in FIG. 8).

Further, a current block made of SiO _{2 is formed} so as to cover the lower surface of the p-type cladding layer 94 other than the ridge 95 and the side surface of the p-type cladding layer 94 from the p-type cladding layer 94 to the active layer 93, the n-type cladding layer 92, and the GaAs substrate 91 on the B2 side. A layer 96 is formed. Further, a p-side pad in which a Cr layer having a thickness of about 10 nm and an Au layer having a thickness of about 2.2 μm are laminated so as to cover the lower surfaces of the ridge 95 (p-type cladding layer 94) and the current blocking layer 96. An electrode 97 is formed.

  Here, in the first embodiment, as shown in FIG. 7, a stepped portion 80 is formed on the surface 91 a of the GaAs substrate 91. Further, the stepped portion 80 includes a bottom surface 80b formed on the B2 side of the GaAs substrate 91 (right end side of the blue-violet semiconductor laser element 50) and a B1 side of the GaAs substrate 91 (waveguide side of the blue-violet semiconductor laser element 50). The upper surface 80c (surface 91a) formed on the upper surface 80c and the side surface 80a extending from the upper surface 80c toward the active layer 93 in an inclined manner. Here, an obtuse ridge is formed by the upper surface 80c and the side surface 80a. The bottom surface 80b is exposed on the outer surface of the infrared semiconductor laser element 90 on the B2 side. The thickness from the bottom surface 80b to the lower surface of the GaAs substrate 91 is about 30 μm. The GaAs substrate 91 and the surface 91a are examples of the “growth substrate” and the “second surface” in the present invention, respectively.

  Further, an n-side ohmic electrode 98 is formed on the bottom surface 80b of the stepped portion 80, in which an AuGe layer and an Ni layer are stacked in this order from the lower layer to the upper layer. Further, the end portion on the B1 side of the n-side ohmic electrode 98 is in contact with the side surface 80a. A pad electrode 99 made of an Au layer is formed on the upper surface of the n-side ohmic electrode 98 and a part of the side surface 80a of the stepped portion 80. Therefore, in the infrared semiconductor laser device 90, the distance (thickness) from the n-side ohmic electrode 98 to the active layer 93 is smaller than the distance (thickness) from the upper surface of the GaAs substrate 91 to the active layer 93. The n-side ohmic electrode 98 is an example of the “electrode layer” in the present invention.

  In the infrared semiconductor laser device 90, the lower surface of the p-side pad electrode 97 and the upper surface of the pad electrode 60 b are bonded via the conductive adhesive layer 9. The lower surface of the p-side pad electrode 97 is an example of the “third surface” in the present invention.

  Further, in the first embodiment, as shown in FIG. 8, the stepped portion 80 of the red semiconductor laser element 70 and the infrared semiconductor laser element 90 has a cavity end face (end of the laser element in the A direction) when viewed in a plan view. Are formed in the central region of the laser element except for the portion. Therefore, the ohmic electrode 78 (98) and the pad electrode 79 (99) are not formed on the resonator end face (end in the A direction).

  Further, as shown in FIG. 7, the blue-violet semiconductor laser device 50 is connected to the lead terminal via a metal wire 81 wire-bonded to the upper surface of the p-side pad electrode 58, and the n-side electrode 59 is electrically conductive. It is electrically fixed to the pedestal 61 via the adhesive layer 9. The red semiconductor laser element 70 is connected to a lead terminal via a metal wire 82 (see FIG. 8) wire-bonded to the pad electrode 60a, and is connected to a pad electrode 79 via a metal wire 83. It is electrically connected to the pedestal 61. The infrared semiconductor laser element 90 is connected to a lead terminal via a metal wire 84 (see FIG. 8) wire-bonded to the pad electrode 60b, and via a metal wire 85 wire-bonded to the pad electrode 99. And is electrically connected to the pedestal 61.

  The wire bond portion of the pad electrode 60a is formed in a portion extending to the B1 side of the blue-violet semiconductor laser device 50, and the wire bond portion of the pad electrode 60b extends to the B2 side of the blue-violet semiconductor laser device 50. It is formed in the part. Thus, in the semiconductor laser device 100, the p-side pad electrodes (58, 77, and 97) of the respective semiconductor laser elements are electrically connected to the lead terminals that are insulated from each other, and the n-side electrodes (59, 78, and 98). ) Are electrically connected to a common negative terminal (cathode common).

  9 to 13 are views for explaining a manufacturing process of the semiconductor laser device according to the first embodiment shown in FIG. A manufacturing process for the semiconductor laser device 100 according to the first embodiment will be now described with reference to FIGS. 7 and 9 to 13. 10, FIG. 12, and FIG. 13 each show a state in the manufacturing process in a cross section taken along line 1100-1100 in FIG.

  In the manufacturing process of the semiconductor laser device 100 according to the first embodiment, first, the n-type cladding layer 52, the active layer 53, and the p-type cladding layer 54 are sequentially formed on the upper surface of the n-type GaN substrate 51 using the MOCVD method. To do. Then, after forming the ridge 56, the current blocking layer 57, the p-side ohmic electrode layer 55, and the p-side pad electrode 58 are formed. Further, by forming the pad electrodes 60a and 60b extending in a strip shape along the resonator direction of the blue-violet semiconductor laser device 50 on a predetermined region of the current blocking layer 57 using a vacuum deposition method, FIG. As shown, a wafer on which the blue-violet semiconductor laser element 50 excluding the n-side electrode 59 (see FIG. 7) is formed is manufactured.

  Next, as shown in FIG. 9, an n-type clad layer 92, an active layer 93, and a p-type clad layer 94 to be the infrared semiconductor laser device 90 are sequentially formed on the upper surface of the GaAs substrate 71 (91). Thereafter, a part of the n-type cladding layer 92, the active layer 93, and the p-type cladding layer 94 is etched to expose a part of the GaAs substrate 71, and the recessed parts 62a and 62b are formed in a part of the exposed part. The n-type clad layer 72, the active layer 73, and the p-type clad layer 74 to be the red semiconductor laser element 70 are sequentially formed, leaving the region to be formed. Thereafter, a ridge 75 (95) and a current blocking layer 76 (96) are formed. Thereafter, the p-side pad electrode 77 is formed by vacuum deposition so as to cover the upper surfaces of the ridge 75 and the current blocking layer 76 and the p-side pad electrode 97 so as to cover the upper surfaces of the ridge 95 and the current blocking layer 96. Form.

Here, in the manufacturing process of the first embodiment, as shown in FIG. 10, by performing wet etching using an etchant adjusted to H ₂ SO ₄ : H ₂ O ₂ = about 3: 1, a GaAs substrate is obtained. A recess 80 d is formed in a predetermined region of the surface 71 a of 71. At this time, as shown in FIG. 11, a plurality of the recesses 80d are formed on the GaAs substrate 71 in a state where they are separated from each other by a predetermined distance in the A direction and the B direction and separated into island shapes. Accordingly, as shown in FIG. 10, the recess 80d has a side surface 80a extending from the surface 71a (upper surface) of the GaAs substrate 71 (91) toward the inside of the substrate and a position different from the surface 71a of the GaAs substrate 71 (91). And has a bottom surface 80b. Thereafter, an n-side ohmic electrode 78 (98) is formed on the bottom surface 80b of the recess 80d using a vacuum deposition method.

  Thereafter, the laminated electrode is heat-treated for about 3 minutes in a nitrogen atmosphere at a temperature of about 500 ° C. As a result, the metal layers are alloyed between the n-side ohmic electrode 78 (98) and the GaAs substrate 71. Thereafter, as shown in FIG. 10, a pad electrode 79 (99) is formed on the n-side ohmic electrode 78 (98) by using a vacuum deposition method.

  Then, as shown in FIG. 12, the wafer on which the blue-violet semiconductor laser element 50 is formed and the wafer on which the red and infrared semiconductor laser elements are formed are bonded. At this time, the upper surface of the pad electrode 60a and the lower surface of the p-side pad electrode 77, and the upper surface of the pad electrode 60b and the lower surface of the p-side pad electrode 97 are bonded via the conductive adhesive layer 9, respectively. As a result, the p-side pad electrode 77 and the pad electrode 60a of the red semiconductor laser element 70 are electrically connected, and the p-side pad electrode 97 and the pad electrode 60b of the infrared semiconductor laser element 90 are electrically connected. Is done.

  Thereafter, as shown in FIG. 13, the surface 71a (upper surface) of the GaAs substrate 71 is polished to reduce the thickness of the GaAs substrate 71 (91) in the region where the recess 80d is not formed. At this time, in the first embodiment, the polishing (thinning) of the GaAs substrate 71 is stopped before the upper surface of the pad electrode 79 (99) is polished. Thereafter, the lower surface of the n-type GaN substrate 51 is polished so that the n-type GaN substrate 51 has a predetermined thickness, and then the n-side electrode 59 (see FIG. 13) is formed on the lower surface of the n-type GaN substrate 51 using a vacuum deposition method. Reference).

  After that, by scribing the surface 71a (upper surface) of the polished GaAs substrate 71 (91) in the A direction at the element isolation position in FIG. 13, as shown in FIG. 13, the GaAs substrate in the region corresponding to the recess 62b. By removing the portion 71 (91) and a part of the recess 80d, the wafer on the GaAs substrate 71 side is separated in the B direction, and the red semiconductor laser element 70 having a predetermined width in the B direction and the infrared Semiconductor laser elements 90 are respectively formed.

  Thereafter, the wafer of blue-violet semiconductor laser device 50 is cleaved into a bar shape so as to have a predetermined resonator length (see FIG. 11), and the resonator end face of each semiconductor laser device is formed. Then, a low-reflectance dielectric multilayer film is formed on the light emitting side resonator end face, and a high-reflectivity dielectric multilayer film is formed on the light reflecting side resonator end face. Thereafter, the bar is divided into elements along the cavity direction (see FIG. 11), thereby forming a plurality of chips of the semiconductor laser device 100 (see FIG. 7).

  Finally, using a ceramic collet (not shown), the semiconductor laser device 100 is fixed while being pressed against the pedestal 61 via the conductive adhesive layer 9. Thus, the semiconductor laser device 100 (see FIG. 7) according to the first embodiment is formed.

  In the first embodiment, as described above, the ohmic electrode 78 (98) and the pad electrode 79 (99) are disposed at the resonator end face positions (cleavage positions in FIG. 11) of the red semiconductor laser element 70 and the infrared semiconductor laser element 90, respectively. ) Is not formed, the wafer can be cleaved (bar-shaped cleavage) in the manufacturing process. Thereby, a favorable cleavage plane (resonator end face) can be formed in each semiconductor laser element.

  In the first embodiment, the optical waveguide (the active layer 73 below the ridge 75 and the active layer 93 below the ridge 95) of the second semiconductor laser element is connected to the active layer 73 in the region facing the upper surface 80c of the stepped portion 80 and Since the optical waveguide is formed in a portion where the thickness of the laser element is large, the thermal distortion is applied to the optical waveguide when the second semiconductor laser element is joined. Can be suppressed. As a result, the lifetime of the red semiconductor laser element 70 and the infrared semiconductor laser element 90 can be extended.

  In the first embodiment, the second semiconductor laser element is a blue-violet semiconductor laser element via the conductive adhesive layer 9 at the third surface portion of the second semiconductor laser element facing the bottom surface 80b of the stepped portion 80. By bonding to 50, strain can be suppressed from being applied to the semiconductor layer below the bottom surface 80b where the thickness of the laser element is small when wire bonding is performed to the bottom surface 80b. In this case, it is more preferable that the conductive adhesive layer 9 is filled between the portion of the third surface facing the bottom surface 80b and the blue-violet semiconductor laser device 50, because the application of strain is further suppressed. As a result, the lifetime of the red semiconductor laser element 70 and the infrared semiconductor laser element 90 can be extended.

  In the manufacturing process of the first embodiment, the second semiconductor laser element can be easily formed by providing the bottom surface 80b of the stepped portion 80 of the second semiconductor laser element on a part of the outer surface of the laser element excluding the cavity end face. The element can be divided along the resonator direction.

  Further, in the manufacturing process of the first embodiment, the stepped portion 80 is formed in a state where the plurality of stepped portions 80 are separated from each other in an island shape as viewed in a plan view, whereby a thick portion of the GaAs substrate 71 is formed. (The portion where the stepped portion 80 is not formed) is left in a lattice shape on the wafer on which the red semiconductor laser device 70 and the infrared semiconductor laser device 90 are integrally formed before bonding. Therefore, even when the plurality of stepped portions 80 are provided, the wafer can be bonded to the wafer of the blue-violet semiconductor laser device 50 while maintaining the strength of the wafer. The other effects of the first embodiment are the same as the effects in the schematic structure and the schematic manufacturing process of the semiconductor laser device.

(Modification of the first embodiment)
FIG. 14 is a cross-sectional view showing the structure of a semiconductor laser device according to a modification of the first embodiment of the present invention. Referring to FIG. 14, in the modification of the first embodiment, unlike the first embodiment, a case where a stepped portion formed only of an inclined surface is formed on the substrate of the red and infrared semiconductor laser elements will be described. To do.

  Here, in the semiconductor laser device 110 according to the modification of the first embodiment, as shown in FIG. 14, the inclined surface 71b is formed on the GaAs substrate 71 of the red semiconductor laser element 70a. An n-side ohmic electrode 78a is formed on the inclined surface 71b. A pad electrode 79a extending from the surface of the n-side ohmic electrode 78a to the upper surface 71c of the GaAs substrate 71 is formed. Similarly, an inclined surface 91b is formed on the GaAs substrate 91 of the infrared semiconductor laser device 90a, and an n-side ohmic electrode 98a is formed on the inclined surface 91b. A pad electrode 99a extending from the surface of the n-side ohmic electrode 98a to the upper surface 91c of the GaAs substrate 91 is formed. The inclined surfaces 71b and 91b are examples of the “side surface of the step portion” in the present invention, and the upper surfaces 71c and 91c are examples of the “second surface” in the present invention. The n-side ohmic electrodes 78a and 98a are examples of the “electrode layer” in the present invention.

  In the modification of the first embodiment, the red semiconductor laser device 70a includes a metal wire 83 bonded to a portion of the pad electrode 79a in a region where the n-side ohmic electrode 78a is not formed in the lower layer, and an infrared ray. In the semiconductor laser device 90a, a metal wire 85 is wire-bonded to a portion of the pad electrode 99a in a region where the n-side ohmic electrode 98a is not formed in the lower layer. The remaining configuration of the semiconductor laser device 110 according to the modification of the first embodiment is the same as that of the first embodiment.

  In the modification of the first embodiment, as described above, the pad electrode 79a (99a) extending from the surface of the n-side ohmic electrode 78a (98a) to the upper surface 71c (91c) of the GaAs substrate 71 (91) is formed. The pad electrode 79a (99a) extending to the upper surface 71c (91c) of the GaAs substrate 71 (91) can be easily electrically connected to the outside of the device.

  In the modification of the first embodiment, the metal wires 83 and 85 are wire-bonded at the portions where the thicknesses of the red semiconductor laser device 70a and the infrared semiconductor laser device 90a are large, resulting in an impact at the time of wire bonding. Damage to the laser element can be suppressed. The remaining effects of the modification of the first embodiment are similar to those of the aforementioned first embodiment.

(Second Embodiment)
15 to 17 are a plan view and a cross-sectional view, respectively, showing the structure of the semiconductor laser device according to the second embodiment of the present invention. 15 to 17, in the second embodiment, unlike the first embodiment, the red semiconductor laser element 270 and the infrared semiconductor laser element 290 are monolithically formed with a predetermined interval therebetween. A case where the wavelength semiconductor laser element 250 is bonded to the blue-violet semiconductor laser element 210 will be described. 16 shows a cross section taken along the line 2000-2000 in FIG. 15, and FIG. 17 shows a cross section taken along the line 2100-2100 in FIG.

  In the semiconductor laser device 200 according to the second embodiment, as shown in FIG. 16, the two-wavelength semiconductor laser element 250 is formed on the surface 210a of the blue-violet semiconductor laser element 210 in which the ridge 220 is shifted to one side (B2 side). Bonded via the conductive adhesive layer 9. The blue-violet semiconductor laser element 210 and the two-wavelength semiconductor laser element 250 are examples of the “first semiconductor laser element” and the “second semiconductor laser element” of the present invention, respectively, and the surface 210a and the n-type contact layer 271 are used. Are examples of the “first surface” and the “first conductivity type semiconductor layer” of the present invention, respectively.

  As shown in FIG. 15, the semiconductor laser device 200 is electrically connected to a pedestal 206, three lead terminals 201, 202, and 203 that are insulated from the pedestal 206 and penetrate the bottom portion 204a, and the pedestal 206 and the bottom portion 204a. And a stem 204 provided with another lead terminal (not shown) that is electrically conductive.

  Further, as shown in FIG. 16, the blue-violet semiconductor laser element 210 is electrically connected to a base 205 made of a conductive material such as AlN through the conductive adhesive layer 9, and the base 205 Is fixed on the upper surface of the base 206 (see FIG. 15) via a conductive adhesive layer (not shown).

  In addition, as shown in FIG. 16, the two-wavelength semiconductor laser element 250 has a red color adjacent to the lower surface of an n-type contact layer 271 made of Si-doped GaAs having a thickness of about 3 μm at a predetermined interval in the B direction. A semiconductor laser element 270 and an infrared semiconductor laser element 290 are formed. The detailed semiconductor element structures of the red semiconductor laser element 270 and the infrared semiconductor laser element 290 are the same as those in the first embodiment. Further, on the upper surface of the n-type contact layer 271, an n-side ohmic electrode 278 that is laminated in the order of the AuGe layer and the Ni layer in order from the n-type contact layer 271 and a pad electrode 279 made of the Au layer are formed in this order. Has been. The n-side ohmic electrode 278 is an example of the “electrode layer” in the present invention.

  In the two-wavelength semiconductor laser device 250, the lower surface of the p-side pad electrode 77 and the upper surface of the pad electrode 260a are bonded via the conductive adhesive layer 9, and the lower surface of the p-side pad electrode 97 and the pad electrode 260b The upper surface is joined via the conductive adhesive layer 9.

  Also, as shown in FIG. 16, the wire bond portion of the pad electrode 260a is formed in a portion extending to the B1 side of the blue-violet semiconductor laser element 210. Thereby, as shown in FIG. 15, the red semiconductor laser element 270 is connected to the lead terminal 202 via the metal wire 281 wire-bonded to the pad electrode 260a. The pad electrode 260b extending in the A direction is formed with a wire bond region 260c (see FIG. 15) protruding in a convex shape toward the B2 side from the position where the infrared semiconductor laser element 290 is bonded in a plan view. Has been. Here, the wire bond region 260 c (see FIG. 17) is formed on the p-side pad electrode 58 via the insulating film 240 and is electrically insulated from the p-side pad electrode 58. Thereby, the infrared semiconductor laser element 290 is connected to the lead terminal 201 (see FIG. 15) via the metal wire 282 wire-bonded to the wire bond region 260c. As shown in FIG. 15, the two-wavelength semiconductor laser element 250 is connected to the base 205 via a metal wire 283 wire-bonded to the pad electrode 279.

  The blue-violet semiconductor laser element 210 is connected to the lead terminal 203 through a metal wire 284 wire-bonded to the wire bond region 58a of the p-side pad electrode 58, and the n-side electrode 59 (see FIG. 16). It is electrically connected to the base 205 (see FIG. 16) through the conductive adhesive layer 9 (see FIG. 16).

  18 to 21 are views for explaining a manufacturing process of the semiconductor laser device according to the second embodiment shown in FIG. A manufacturing process for the semiconductor laser device 200 according to the second embodiment is now described with reference to FIGS. 15, 16 and 18 to 21. 20 and 21 show states in the manufacturing process in the cross section taken along the line 2000-2000 in FIG.

  First, a wafer of blue-violet semiconductor laser element 210 (see FIG. 16) is manufactured by the same manufacturing process as in the first embodiment. Thereafter, as shown in FIG. 15, an insulating film 240 is formed on the p-side pad electrode 58 and a part of the current blocking layer 57 so that the wire bond region 58a is exposed. Thereafter, pad electrodes 260a and 260b are patterned so as to cover predetermined regions of insulating film 240 and current blocking layer 57.

Next, as shown in FIG. 18, an etching stopper layer 252 made of Al _0.5 Ga _0.5 As having a thickness of about 0.1 μm and an n-type contact layer 271 are stacked on the upper surface of the GaAs substrate 251. To do. Thereafter, the red semiconductor laser element 270 and the infrared semiconductor laser element 290 are formed on the upper surface of the n-type contact layer 271 so as to be spaced apart from each other by a predetermined manufacturing process as in the first embodiment. Thus, a wafer of the two-wavelength semiconductor laser element 250 is manufactured. The GaAs substrate 251 is an example of the “growth substrate” in the present invention.

  Here, in the manufacturing process of the second embodiment, as shown in FIG. 19, by performing wet etching using an ammonia-based etchant, a predetermined surface 251a of the GaAs substrate 251 opposite to the n-type contact layer 271 is formed. A recess 280c having a side surface 280a is formed in this region. At this time, the etching stops at the interface between the etching stopper layer 252 and the n-type contact layer 271. Thereafter, the etching stopper layer 252 exposed at the bottom of the recess 280c is removed by wet etching with hydrofluoric acid or hydrochloric acid, and the upper surface of the n-type contact layer 271 is exposed. Thereafter, an n-side ohmic electrode 278 and a pad electrode 279 are sequentially formed on the bottom surface 280b of the recess 280c using a vacuum deposition method. The surface 251a is an example of the “second surface” in the present invention.

  Thereafter, in order to alloy the n-side ohmic electrode 278 and the n-type contact layer 271, heat treatment is performed in a nitrogen atmosphere.

  Thereafter, the wafer on which the blue-violet semiconductor laser element 210 is formed and the wafer on which the two-wavelength semiconductor laser element 250 is formed are bonded. At this time, the pad electrode 260a and the p-side pad electrode 77, and the pad electrode 260b and the p-side pad electrode 97 are bonded through the conductive adhesive layer 9 while facing each other.

  Thereafter, as shown in FIG. 20, the entire GaAs substrate 251 is removed by performing wet etching using an ammonia-based etchant. Further, the etching stopper layer 252 (see FIG. 19) is completely removed by wet etching using hydrofluoric acid or hydrochloric acid. As a result, only the n-side ohmic electrode 278 and the pad electrode 279 are left on the n-type contact layer 271. Thereafter, the lower surface of the n-type GaN substrate 51 is polished, and then an n-side electrode 59 is formed on the lower surface of the n-type GaN substrate 51 using a vacuum deposition method.

  Thereafter, as shown in FIG. 21, the n-type contact layer 271 in the region where the element structures of the red semiconductor laser element 270 and the infrared semiconductor laser element 290 are not formed is removed by scribing or the like. As a result, the wafer is separated in the B direction, and the two-wavelength semiconductor laser element 250 having a predetermined width in the B direction is formed. Finally, a plurality of semiconductor laser devices 200 (see FIG. 16) are formed by cleaving the wafer of the blue-violet semiconductor laser element 210 in a bar shape so as to have a predetermined resonator length and dividing the wafer along the resonator direction. Chips are formed.

  In the manufacturing process of the second embodiment, as described above, the bottom surface of the recess 280c is formed by forming the recess 280c on the surface 251a side of the GaAs substrate 251 on which the n-type contact layer 271 is stacked via the etching stopper layer 252. 280b can be formed in the vicinity of the etching stopper layer 252. Thereby, the bottom surface 280b can be brought closer to the active layer 73 (93) with a high yield. The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

(Third embodiment)
22 to 25 are a plan view and a cross-sectional view, respectively, showing the structure of the semiconductor laser device according to the third embodiment of the present invention. 22 to 25, in the third embodiment, unlike the second embodiment, the thickness in the vicinity of the resonator end face of the two-wavelength semiconductor laser element 350 is set in the central region in the resonator direction by the step portion 380. The case where it is formed smaller than the thickness will be described. 23 shows a cross section taken along the line 3000-3000 in FIG. 22, and FIG. 24 shows a cross section taken along the line 3100-3100 in FIG. FIG. 25 shows a cross section taken along line 3200-3200 in FIG.

  In the semiconductor laser device 300 according to the third embodiment, a two-wavelength semiconductor laser element 350 is bonded to the surface 310a of the blue-violet semiconductor laser element 310 via the conductive adhesive layer 9, as shown in FIG. The blue-violet semiconductor laser element 310 is an example of the “first semiconductor laser element” in the present invention, and the two-wavelength semiconductor laser element 350 is an example of the “second semiconductor laser element” in the present invention. The surface 310a is an example of the “first surface” in the present invention.

As shown in FIG. 24, the two-wavelength semiconductor laser element 350 includes a red semiconductor laser on the lower surface of the GaAs substrate 351 via an Al _0.5 Ga _0.5 As etching stopper layer 252 and an n-type contact layer 271. The element 370 and the infrared semiconductor laser element 390 are formed at a predetermined interval in the B direction. The detailed semiconductor element structures of the red semiconductor laser element 370 and the infrared semiconductor laser element 390 are the same as those in the second embodiment. The GaAs substrate 351 is an example of the “growth substrate” in the present invention.

  Here, in the third embodiment, when the two-wavelength semiconductor laser element 350 is seen in a cross section (3200-3200 cross section in FIG. 22) along the resonator direction (A direction), as shown in FIG. A stepped portion 380 is formed on the surface 351a (upper surface) of the GaAs substrate 351 in the vicinity of the end surface 300a. Further, the stepped portion 380 is formed with a side surface 380a extending obliquely from the surface 351a of the GaAs substrate 351 toward the active layer 93, and a bottom surface 380b that continues to the side surface 380a and whose end is exposed to the resonator end surface 300a. Yes. An n-side ohmic electrode 378 is formed so as to cover the bottom surface 380b and the side surface 380a of the stepped portion 380. A pad electrode 379 is continuously formed on the upper surface of the n-side ohmic electrode 378 and the surface 351a of the GaAs substrate 351. The surface 351a and the n-side ohmic electrode 378 are examples of the “second surface” and the “electrode layer” in the present invention, respectively.

  As shown in FIG. 23, the wire bond portion of the pad electrode 360a is formed in a portion extending to the B1 side of the blue-violet semiconductor laser device 310. As shown in FIG. 22, the pad electrode 360b (see FIG. 24) extending in the A direction protrudes in a convex shape from the position where the infrared semiconductor laser element 390 is bonded to the B2 side when seen in a plan view. A wire bond region 360c is formed. Here, the wire bond region 360 c is formed on the p-side pad electrode 358 via the insulating film 340 and insulated from the p-side pad electrode 358. Thus, the infrared semiconductor laser element 390 is connected to the lead terminal via the metal wire 382 wire-bonded to the wire bond region 360c. As shown in FIG. 24, the two-wavelength semiconductor laser element 350 is connected to the base 205 through a metal wire 383 wire-bonded to the pad electrode 379.

  The blue-violet semiconductor laser device 310 is connected to a lead terminal via a metal wire 384 wire-bonded to the wire bond region 358a of the p-side pad electrode 358, and the n-side electrode 59 (see FIG. 23) is conductive. It is electrically connected to the base 205 via the adhesive adhesive layer 9.

  FIG. 26 is a diagram for explaining a manufacturing process for the semiconductor laser device according to the third embodiment shown in FIG. Next, with reference to FIGS. 22, 23, 25 and 26, a manufacturing process of the semiconductor laser device 300 according to the third embodiment will be described. 23 shows a cross section taken along line 3000-3000 in FIG. 26, and FIG. 24 shows a cross section taken along line 3100-3100 in FIG.

  First, a wafer of the blue-violet semiconductor laser device 310 (see FIG. 23) is manufactured by the same manufacturing process as in the first embodiment. Thereafter, as shown in FIG. 22, an insulating film 340 is formed on the p-side pad electrode 358 and a part of the current blocking layer 57 so that the wire bond region 358a is exposed. Thereafter, pad electrodes 360a and 360b are patterned to cover predetermined regions of insulating film 340 and current blocking layer 57.

  Next, a wafer of the two-wavelength semiconductor laser element 350 is manufactured by a manufacturing process similar to that of the second embodiment.

  Here, in the manufacturing process of the third embodiment, as shown in FIG. 26, by performing wet etching using an ammonia-based etchant, a predetermined surface 351a of the GaAs substrate 351 opposite to the n-type contact layer 271 is formed. A recess 380c is formed in the region. At this time, the etching stops at the interface between the etching stopper layer 252 (see FIG. 25) and the n-type contact layer 271 (see FIG. 25). Thereafter, the etching stopper layer 252 exposed at the bottom of the recess 380c is removed by wet etching to expose the upper surface of the n-type contact layer 271 (see FIG. 25). Thereafter, an n-side ohmic electrode 378 is formed on the bottom surface 380b and the side surface 380a of the recess 380c by using a vacuum deposition method. In this state, in order to alloy the n-side ohmic electrode 378 and the n-type contact layer 271, heat treatment is performed in a nitrogen atmosphere.

  Thereafter, after bonding the wafer on which the blue-violet semiconductor laser element 310 is formed and the wafer on which the two-wavelength semiconductor laser element 350 is formed, the GaAs substrate 351 (see FIG. 26) in the region where the recess 380c is not formed. By polishing the surface 351a toward the active layer 73 (93), the thickness of the GaAs substrate 351 in this region is reduced. Thereafter, unnecessary portions are removed at the element separation position of the two-wavelength semiconductor laser element 350, so that only the bottom surface 380b of the step portion 380 is located at the cleavage position (see FIG. 26), and the step portion 380 is located at this position. The upper surface and the side surface 380a are not formed. Thereafter, a pad electrode 379 (see FIG. 25) is formed so as to cover the n-side ohmic electrode 378 and the polished surface 351a of the GaAs substrate 351 by vacuum deposition.

  Thereafter, at the cleavage position shown in FIG. 26, the wafer of blue-violet semiconductor laser element 310 is cleaved in a bar shape so as to have a predetermined resonator length. Finally, by dividing the element along the resonator direction (A direction), a plurality of chips of the semiconductor laser device 300 (see FIG. 23) are formed.

  In the third embodiment, as described above, by forming the etching stopper layer 252 between the GaAs substrate 351 and the n-type contact layer 271, the bottom surface 380b of the stepped portion 380 (recessed portion 380c) is formed on the etching stopper layer 252. It can be formed in the vicinity. Thereby, the bottom surface 380b can be brought closer to the active layer 73 (93) with a high yield.

  In the third embodiment, a ridge 75 (optical waveguide of the red semiconductor laser element 370) and a ridge 95 (infrared semiconductor laser element) are disposed in a region facing the bottom surface 380b of the stepped portion 380 of the two-wavelength semiconductor laser element 350 in a plane. 390 optical waveguide), the distance between the n-side ohmic electrode 378 and the active layer 73 (93) is reduced, so that the electric current between the n-side ohmic electrode 378 and the active layer 73 (93) is reduced. Resistance can be easily reduced. Thereby, since the operating voltage of the two-wavelength semiconductor laser element 350 is reduced, the heat generation of the semiconductor laser device 300 can be suppressed. Further, since the distance between the n-side ohmic electrode 378 and the active layer 73 (93) is reduced, heat conduction from the light emitting region of the active layer 73 (93) to the n-side ohmic electrode 378 is improved. An excessive temperature rise of the active layer 73 (93) during the laser element operation can be suppressed.

  In the third embodiment, since the end portion of the bottom surface 380b of the stepped portion 380 is formed so as to be exposed to the resonator end surface 300a, the thickness of the element can be reduced on the resonator end surface 300a. In addition, the wafer can be easily cleaved (bar-shaped cleavage). The remaining effects of the third embodiment are similar to those of the aforementioned first embodiment.

(Modification of the third embodiment)
27 to 29 are views showing the structure and manufacturing process of a semiconductor laser device according to a modification of the third embodiment of the present invention. With reference to FIGS. 27 to 29, in the modification of the third embodiment, a case where the stepped portion 385 is formed in the substantially central portion of the two-wavelength semiconductor laser element 355 will be described, unlike the third embodiment. . FIG. 28 shows a cross-sectional view taken along line 3500-3500 in FIGS.

  Here, in the modification of the third embodiment, as shown in FIGS. 27 and 28, the stepped portion 385 is formed so as to be positioned at a substantially central portion in the A direction and the B direction of the two-wavelength semiconductor laser element 355. Yes. That is, in the manufacturing process of the two-wavelength semiconductor laser element 355, as shown in FIGS. 28 and 29, the surface 351a of the GaAs substrate 351 in the region where the red semiconductor laser element 370 and the infrared semiconductor laser element 390 face each other in the B direction. A stepped portion 385 is formed. Then, similar to the manufacturing process of the third embodiment, an unnecessary portion is removed at the element isolation position (see FIG. 29) of the two-wavelength semiconductor laser element 355, and then the n-side ohmic electrode 378 is used by vacuum deposition. And a pad electrode 379 (see FIG. 28). The remaining configuration, manufacturing process, and effects of the semiconductor laser device 305 according to the modification of the third embodiment are the same as those of the third embodiment.

(Fourth embodiment)
30 and 31 are a plan view and a cross-sectional view, respectively, showing the structure of the RGB three-wavelength semiconductor laser device according to the fourth embodiment of the present invention. Referring to FIGS. 30 and 31, in the fourth embodiment, a red semiconductor laser element 470 is bonded onto a surface 450a of a two-wavelength semiconductor laser element 450 including a green semiconductor laser element 410 and a blue semiconductor laser element 420. Will be described. The two-wavelength semiconductor laser element 450 is an example of the “first semiconductor laser element” in the present invention, and the red semiconductor laser element 470 is an example of the “second semiconductor laser element” in the present invention. The surface 450a is an example of the “first surface” in the present invention.

  In the RGB three-wavelength semiconductor laser device 400 according to the fourth embodiment, as shown in FIG. 31, a red semiconductor laser element 470 is formed on a monolithic two-wavelength semiconductor laser element 450 including a green semiconductor laser element 410 and a blue semiconductor laser element 420. Are joined via the conductive adhesive layer 9.

Further, as shown in FIG. 31, the red semiconductor laser element 470 has an Al _0.5 Ga _0.5 As etching stopper layer 252, an n-type cladding layer 72, on the lower surface of a GaAs substrate 471 having a thickness of about 60 μm. An active layer 73 and a p-type cladding layer 74 are formed. Further, the ridge 75 is formed at a substantially central portion of the element.

  Here, in the fourth embodiment, a stepped portion 480 is formed on the surface 471a of the GaAs substrate 471. Further, the step portion 480 is formed in the vicinity of the position where the bottom surface 480 b faces the ridge 75. An n-side ohmic electrode 478 is formed on the bottom surface 480b of the step portion 480. A pad electrode 479 is continuously formed on the upper surface of the n-side ohmic electrode 478, the side surface 480a of the stepped portion 480, and the surface 471a of the GaAs substrate 471. The surface 471a and the n-side ohmic electrode 478 are examples of the “second surface” and the “electrode layer” in the present invention, respectively.

  As shown in FIG. 31, the green semiconductor laser device 410 includes an n-type cladding layer 412 made of n-type AlGaN, an active layer 413, and a p-type cladding layer made of p-type AlGaN on the upper surface of an n-type GaN substrate 411. 414 and a p-side ohmic electrode layer 415 are formed. The blue semiconductor laser element 420 includes an n-type cladding layer 422 made of n-type AlGaN, an active layer 423, a p-type cladding layer 424 made of p-type AlGaN, and a p-side ohmic electrode layer on the upper surface of the n-type GaN substrate 411. 425 is formed.

  Further, the upper surface of the flat portion of the p-type cladding layer 414 and the side surface of the ridge 401 of the green semiconductor laser device 410 and the upper surface of the flat portion of the p-type cladding layer 424 of the blue semiconductor laser device 420 and the side surface of the ridge 421 are covered. A current blocking layer 416 is formed. Further, a current blocking layer 426 is formed so as to cover the lower surface on the B2 side of the p-type cladding layer 424 when viewed from the ridge 421. A p-side pad electrode 417 is formed on the upper surfaces of the ridge 401 and the current blocking layer 416, and a p-side pad electrode 427 is formed on the upper surfaces of the ridge 421 and the current blocking layers 416 and 426. Further, an n-side electrode 419 composed of a Pt layer, a Pd layer, and an Au layer is formed on the lower surface of the n-type GaN substrate 411 in the order closer to the n-type GaN substrate 411.

  A pad electrode 460 made of Au or the like is formed on the upper surface of the current blocking layer 416 on the B1 side of the two-wavelength semiconductor laser element 450. Thereby, the red semiconductor laser element 70 (the lower surface of the p-side pad electrode 77) is bonded to the surface 450a of the two-wavelength semiconductor laser element 450 at the position where the pad electrode 460 is provided.

  Further, as shown in FIG. 31, the green semiconductor laser element 410 is connected to the lead terminal via a metal wire 481 wire-bonded to the p-side pad electrode 417, and the blue semiconductor laser element 420 is connected to the p-side pad. The lead terminal is connected via a metal wire 482 wire-bonded to the electrode 427. The red semiconductor laser element 470 is connected to a lead terminal via a metal wire 483 (see FIG. 32) wire-bonded to the pad electrode 460, and is connected to the wire bond region 479a at the B1 side end of the pad electrode 479. It is electrically connected to the base 205 via a wire-bonded metal wire 484. Further, the n-side electrode 419 of the two-wavelength semiconductor laser element 450 is electrically connected to the base 205 through the conductive adhesive layer 9.

  The remaining structure and manufacturing process of the RGB three-wavelength semiconductor laser device 400 according to the fourth embodiment are the same as those of the first embodiment. The effect of the fourth embodiment is the same as that of the first embodiment.

(Fifth embodiment)
32 to 34 are a plan view and a cross-sectional view, respectively, showing the structure of the semiconductor laser device according to the fifth embodiment of the present invention. With reference to FIGS. 32 to 34, in the fifth embodiment, unlike the fourth embodiment, a step 580 is provided in a two-wavelength semiconductor laser element 550 including a red semiconductor laser element 570 and an infrared semiconductor laser element 590. The case where it is formed will be described. 33 shows a cross section taken along the line 5000-5000 in FIG. 32, and FIG. 34 shows a cross section taken along the line 5100-5100 in FIG.

  In the semiconductor laser device 500 according to the fifth embodiment, as shown in FIG. 33, a blue-violet semiconductor laser element 510 is formed on a surface 550a of a two-wavelength semiconductor laser element 550 including a red semiconductor laser element 570 and an infrared semiconductor laser element 590. The surface 510 a (the lower surface of the p-side pad electrode 58) is bonded via the conductive adhesive layer 9. The surface 550a is an example of the “third surface” in the present invention, and the surface 510a is an example of the “first surface” in the present invention.

  In the blue-violet semiconductor laser element 510, an n-side ohmic electrode 518 and a pad electrode 519 are formed on the upper surface of the n-type cladding layer 52.

As shown in FIGS. 33 and 34, the two-wavelength semiconductor laser element 550 is formed on the upper surface of the GaAs substrate 551 via the Al _0.5 Ga _0.5 As etching stopper layer 252 and the n-type contact layer 271. A red semiconductor laser element 570 and an infrared semiconductor laser element 590 are formed at a predetermined interval. The GaAs substrate 551 is an example of the “growth substrate” in the present invention.

  Here, in the fifth embodiment, as shown in FIG. 34, a step 580 is formed on the surface 551a (lower surface) of the GaAs substrate 551. Further, the step portion 580 is formed with a side surface 580a extending obliquely from the surface 551a of the GaAs substrate 551 toward the active layer 73 (93) and a bottom surface 580b following the side surface 580a. An n-side ohmic electrode 578 is formed so as to cover the bottom surface 580b of the step portion 580. A pad electrode 579 is continuously formed on the lower surface of the n-side ohmic electrode 378, the side surface 580a, and the surface 551a (lower surface) of the GaAs substrate 551. The surface 551a and the n-side ohmic electrode 578 are examples of the “second surface” and the “electrode layer” in the present invention, respectively. The two-wavelength semiconductor laser element 550 is electrically fixed to the base 205 through the conductive adhesive layer 9 formed on the lower surface of the pad electrode 579.

  A pad electrode 560 is formed on the upper surface of the current blocking layer 57 on the B1 side of the two-wavelength semiconductor laser element 550. Thus, the blue-violet semiconductor laser element 510 is bonded to the two-wavelength semiconductor laser element 550 at the position where the pad electrode 560 is provided.

  35 to 37 are views for explaining a manufacturing process of the semiconductor laser device according to the fifth embodiment shown in FIG. A manufacturing process for the semiconductor laser device 500 according to the fifth embodiment is now described with reference to FIGS. 35 and 36 show a state in the manufacturing process in the cross section taken along the line 5000-5000 in FIG.

  First, a release layer 512 is formed on the upper surface of the n-type GaN substrate 511. Then, a wafer of blue-violet semiconductor laser element 510 (see FIG. 35) is manufactured by the same manufacturing process as in the first embodiment.

  Next, a wafer of the two-wavelength semiconductor laser element 550 is manufactured by a manufacturing process similar to that of the second embodiment. At this time, as shown in FIG. 35, a step 580 is formed in a predetermined region of the surface 551a of the GaAs substrate 551 by etching, and an n-side ohmic electrode is formed on the bottom surface 580b of the step 580 using a vacuum deposition method. 578 is formed. Thereafter, heat treatment for alloying the n-side ohmic electrode 578 and the n-type contact layer 271 is performed.

Then, after bonding the wafer on which the blue-violet semiconductor laser element 510 is formed and the wafer on which the two-wavelength semiconductor laser element 550 is formed, as shown in FIG. 36, the peeling layer is formed from the upper surface side of the n-type GaN substrate 511. Laser irradiation is performed toward 512. At that time, the second harmonic (wavelength: about 532 nm) of the Nd: YAG laser light is adjusted to an energy density of about 500 to about 2000 mJ / cm ² , and the n-type GaN substrate 511 from above the n-type GaN substrate 511. Irradiate intermittently. As a result, the crystal bond of the peeling layer 512 is decomposed and evaporated, and the n-type GaN substrate 511 is peeled from the semiconductor element layer.

  Thereafter, the surface 551a of the GaAs substrate 551 is polished toward the active layer 73 (93), thereby reducing the thickness of the GaAs substrate 551 in the region where the step portion 580 is not formed. Thereafter, a pad electrode 579 is formed using a vacuum deposition method so as to cover the n-side ohmic electrode 578 and the polished lower surface of the GaAs substrate 551.

  Thereafter, at the cleavage position shown in FIG. 37, the wafer of the two-wavelength semiconductor laser element 550 is cleaved in a bar shape so as to have a predetermined resonator length, and the resonator end face of each semiconductor laser element is formed. At this time, the cleavage is performed so that only the bottom surface 580b of the step portion 580 is located at the cleavage position. Finally, by dividing the element along the resonator direction, a plurality of chips of the semiconductor laser device 500 (see FIG. 33) are formed.

  In the fifth embodiment, as described above, the step portion 580 extending from the surface 551a of the GaAs substrate 551 toward the active layer 73 (93), the n-side ohmic electrode 578 formed on the bottom surface 580b of the step portion 580, The distance from the n-side ohmic electrode 578 to the active layer 73 (93) is made smaller than the distance from the lower surface of the GaAs substrate 551 to the active layer 73 (93). Therefore, the electrical resistance between the n-side ohmic electrode 578 and the active layer 73 (93) can be reduced. Thereby, since the operating voltage of the two-wavelength semiconductor laser element 550 is reduced, heat generation of the semiconductor laser device 500 can be suppressed. The remaining effects of the fifth embodiment are similar to those of the aforementioned first embodiment.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first embodiment, the example in which the blue-violet semiconductor laser device 50 is directly fixed to the pedestal 61 via the conductive adhesive layer 9 has been described. However, the present invention is not limited to this, and the second to fifth embodiments are not limited thereto. Similarly to the embodiment, the blue-violet semiconductor laser element 50 may be bonded to the base 205 via the conductive adhesive layer 9 and the base 205 may be fixed to the base 61 via the conductive adhesive layer.

  In the first embodiment, the example in which the semiconductor laser device is formed by bonding the red semiconductor laser element 70 and the infrared semiconductor laser element 90 on the blue-violet semiconductor laser element 50 has been described. The two-wavelength semiconductor laser element may be formed by bonding any one of the red semiconductor laser element and the infrared semiconductor laser element on the blue-violet semiconductor laser element.

  In the second and third embodiments, the example in which the base 205 to which the blue-violet semiconductor laser element 210 (310) is bonded is configured by a substrate made of AlN is shown, but the present invention is not limited to this. The base 205 may be configured using a conductive material having good thermal conductivity, such as Fe or Cu.

  In the fourth embodiment, the green semiconductor laser device and the blue semiconductor laser device are both formed on the common n-type GaN substrate 411. However, the present invention is not limited to this, and the green semiconductor laser device and Both blue semiconductor laser elements may be formed on a common semiconductor layer such as an n-type GaN layer.

  In the first to fourth embodiments, an example in which a ridge waveguide semiconductor laser is formed has been described. However, the present invention is not limited to this, and a ridge waveguide semiconductor laser having a semiconductor block layer, or an embedded semiconductor laser. A gain-guided semiconductor laser in which a heterostructure (BH) semiconductor laser or a current blocking layer having a stripe-shaped opening on a flat upper cladding layer may be formed.

  Moreover, in the said 1st-5th embodiment, you may form so that the bottom face of a level | step-difference part may be located in an n-type contact layer or an n-type clad layer.

  In the third to fifth embodiments, the example in which the ohmic electrode and the pad electrode are exposed on the cavity end face of the semiconductor laser element has been described. However, the present invention is not limited to this, and the ohmic electrode and the pad are also provided. The electrode may not be formed only in the vicinity of the resonator surface position (cleavage position). Thereby, since the ohmic electrode and the pad electrode are not formed at the resonator surface position, the cleavage can be performed more favorably, and a favorable resonator end surface (cleavage surface) can be formed.

It is sectional drawing for demonstrating the schematic structure of the semiconductor laser apparatus of this invention. It is a figure for demonstrating the schematic manufacturing process of the semiconductor laser apparatus shown in FIG. It is a figure for demonstrating the schematic manufacturing process of the semiconductor laser apparatus shown in FIG. It is a figure for demonstrating the schematic manufacturing process of the semiconductor laser apparatus shown in FIG. It is a figure for demonstrating the schematic manufacturing process of the semiconductor laser apparatus shown in FIG. It is a figure for demonstrating the schematic manufacturing process of the semiconductor laser apparatus shown in FIG. It is sectional drawing which showed the structure of the semiconductor laser apparatus by 1st Embodiment of this invention. 1 is a plan view showing a structure of a semiconductor laser device according to a first embodiment of the present invention. FIG. 8 is a drawing for explaining the manufacturing process for the semiconductor laser device according to the first embodiment shown in FIG. 7; FIG. 8 is a drawing for explaining the manufacturing process for the semiconductor laser device according to the first embodiment shown in FIG. 7; FIG. 8 is a drawing for explaining the manufacturing process for the semiconductor laser device according to the first embodiment shown in FIG. 7; FIG. 8 is a drawing for explaining the manufacturing process for the semiconductor laser device according to the first embodiment shown in FIG. 7; FIG. 8 is a drawing for explaining the manufacturing process for the semiconductor laser device according to the first embodiment shown in FIG. 7; It is sectional drawing which showed the structure of the semiconductor laser apparatus by the modification of 1st Embodiment of this invention. It is the top view which showed the structure of the semiconductor laser apparatus by 2nd Embodiment of this invention. It is sectional drawing along the 2000-2000 line of FIG. FIG. 16 is a cross-sectional view taken along line 2100-2100 in FIG. 15. FIG. 16 is a diagram for explaining a manufacturing process for the semiconductor laser device according to the second embodiment shown in FIG. 15; FIG. 16 is a diagram for explaining a manufacturing process for the semiconductor laser device according to the second embodiment shown in FIG. 15; It is the figure which showed the state in the manufacturing process in the cross section along the 2000-2000 line of FIG. It is the figure which showed the state in the manufacturing process in the cross section along the 2000-2000 line of FIG. It is the top view which showed the structure of the semiconductor laser apparatus by 3rd Embodiment of this invention. It is sectional drawing along the 3000-3000 line of FIG. FIG. 23 is a cross-sectional view taken along line 3100-3100 in FIG. 22. It is sectional drawing along the 3200-3200 line | wire of FIG. FIG. 23 is a diagram for explaining a manufacturing process for the semiconductor laser device according to the third embodiment shown in FIG. 22; It is the top view which showed the structure of the semiconductor laser apparatus by the modification of 3rd Embodiment of this invention. It is sectional drawing along the 3500-3500 line | wire of FIG. It is a figure for demonstrating the manufacturing process of the semiconductor laser apparatus by the modification of 3rd Embodiment of this invention. It is the top view which showed the structure of the RGB 3 wavelength semiconductor laser apparatus by 4th Embodiment of this invention. It is sectional drawing along the 4000-4000 line | wire of FIG. It is the top view which showed the structure of the semiconductor laser apparatus by 5th Embodiment of this invention. It is sectional drawing along the 5000-5000 line | wire of FIG. FIG. 33 is a cross-sectional view taken along line 5100-5100 in FIG. 32. FIG. 33 is a diagram for explaining a manufacturing process for the semiconductor laser device according to the fifth embodiment shown in FIG. 32; FIG. 33 is a diagram for explaining a manufacturing process for the semiconductor laser device according to the fifth embodiment shown in FIG. 32; FIG. 33 is a diagram for explaining a manufacturing process for the semiconductor laser device according to the fifth embodiment shown in FIG. 32;

Explanation of symbols

10 First semiconductor laser element 10a, 50a, 210a, 310a, 450a, 510a Surface (first surface)
20 Second semiconductor laser element 21 First conductive type semiconductor layer 21a, 71a, 91a, 251a, 351a, 471a, 551a Surface (second surface)
22, 73, 93 Active layer 23 Second conductive type semiconductor layer 24 First conductive side electrode (electrode layer)
30, 280 Concave part (step part)
30a, 80a, 280a, 380a, 480a, 580a Side surface 30b, 80b, 280b, 380b, 480b, 580b Bottom surface 50, 210, 310 Blue-violet semiconductor laser element (first semiconductor laser element)
70, 70a, 270 Red semiconductor laser element (second semiconductor laser element)
71, 91, 251, 351, 551 GaAs substrate (growth substrate)
71b, 91b Inclined surface (side surface of step)
71c, 91c Upper surface (second surface)
72, 92 n-type cladding layer (first conductivity type semiconductor layer)
74, 94 p-type cladding layer (second conductivity type semiconductor layer)
78, 78a, 98, 98a, 278, 378, 478, 578 n-side ohmic electrode (electrode layer)
80, 380, 385, 480, 580 Stepped portion 90, 90a, 290 Infrared semiconductor laser element (second semiconductor laser element)
271 n-type contact layer (first conductivity type semiconductor layer)
350, 550 2-wavelength semiconductor laser element (second semiconductor laser element)
450 Two-wavelength semiconductor laser element (first semiconductor laser element)
470 Red semiconductor laser element (second semiconductor laser element)
550a surface (third surface)

Claims (6)

A first semiconductor laser element including a first surface;
A second surface having a stepped portion, a third surface formed on the opposite side of the second surface, and an active layer formed between the second surface and the third surface, A second semiconductor laser element having the surface joined to the third surface,
The second semiconductor laser element further includes an electrode layer formed on at least one of a side surface or a bottom surface of the stepped portion extending from the second surface toward the first semiconductor laser element side. .   The second semiconductor laser element includes: a first conductivity type semiconductor layer formed on the second surface side of the active layer; and a second conductivity type semiconductor layer formed on the third surface side of the active layer. The semiconductor laser device according to claim 1, further comprising: Forming a first semiconductor laser element including a first surface;
On the surface of the growth substrate, on the second surface provided on the growth substrate side, on the third surface provided on the opposite side of the second surface, on the third surface side of the growth substrate Forming a second semiconductor laser element including an active layer provided;
Bonding the third surface to the first surface,
The step of forming the second semiconductor laser element includes a step of forming a stepped portion extending from the second surface toward the first semiconductor laser element side, and on at least one surface of the side surface or the bottom surface of the stepped portion. A method of manufacturing a semiconductor laser device, comprising: forming an electrode layer.   The semiconductor laser according to claim 3, further comprising a step of removing the growth substrate or reducing a thickness of the growth substrate while leaving the electrode layer after the bonding step. Device manufacturing method.   The method of manufacturing a semiconductor laser device according to claim 4, wherein the step portion is formed such that the plurality of step portions are separated from each other in an island shape.   The step of forming the second semiconductor laser element includes the step of alloying the electrode layer prior to the step of bonding the second semiconductor laser element to the first semiconductor laser element. The manufacturing method of the semiconductor laser apparatus of any one of Claims 1.

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