JP2006278578A - Integrated semiconductor laser element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an integrated semiconductor laser element which can improve a characteristic of a laser beam and reduce cost for optical axis adjustment and whose degree of freedom on an applying method of voltage is high. <P>SOLUTION: The integrated semiconductor laser element is provided with a violet laser element 110 comprising a light emitting point 13 and having a projection 18 for positioning, and a red laser element 120 comprising a light emitting point 34 and having a recess 38 for positioning. The projection 18 for positioning the violet laser element 110 is engaged with the recess 38 for positioning the red laser element 120, in a state where an insulating film 12 and a solder layer 115a are installed between a p-side electrode 10 of the violet laser element 110 and a p-side electrode 31 of the red laser element 120. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an integrated semiconductor laser device including a plurality of semiconductor laser devices and a method for manufacturing the same.

  Conventionally, an integrated semiconductor laser element in which a plurality of semiconductor laser elements are integrated in the stacking direction of semiconductor layers is known (see, for example, Patent Document 1).

  FIG. 25 is a perspective view showing the structure of a conventional integrated semiconductor laser device. As shown in FIG. 25, in the conventional integrated semiconductor laser element, the first semiconductor laser element 310 and the second semiconductor laser element 320 are integrated in the stacking direction (vertical direction) of the semiconductor layers.

  A ridge portion 312 and a recess 313 are formed in the semiconductor element layer 311 constituting the first semiconductor laser element 310. The ridge 312 and the recess 313 are arranged at a predetermined interval in the horizontal direction. A region in the vicinity of the ridge portion 312 of the semiconductor element layer 311 becomes a light emitting point 314 of the first semiconductor laser element 310. In addition, a ridge portion 322 and a concave portion 323 are formed in the semiconductor element layer 321 constituting the second semiconductor laser element 320. The ridge portion 322 and the concave portion 323 are arranged at a predetermined interval in the horizontal direction. A region near the ridge portion 322 of the semiconductor element layer 321 becomes a light emitting point 324 of the second semiconductor laser element 321.

In addition, the first semiconductor laser element 310 and the second semiconductor laser element 320 are bonded to each other through bonding layers 315 and 325. Specifically, the ridge portion 312 of the first semiconductor laser element 310 and the concave portion 323 of the second semiconductor laser element 320 face each other, and the ridge portion 322 of the second semiconductor laser element 320 and the first ridge portion 322 The second semiconductor laser element 320 is bonded onto the first semiconductor laser element 310 so as to face the concave portion 313 of the semiconductor laser element 310.
JP 2002-299739 A

  However, in the conventional integrated semiconductor laser device shown in FIG. 25, the ridge portion 312 and the ridge portion 322 of the first semiconductor laser device 310 and the second semiconductor laser device 320 are the same as the second semiconductor laser device 320 and the second semiconductor laser device 320. Each of the semiconductor laser elements 310 is not fitted into the recess 323 and the recess 313. For this reason, when the first semiconductor laser element 310 and the second semiconductor laser element 320 are bonded together, the first semiconductor laser element 310 and the second semiconductor laser element 320 are prevented from moving in the horizontal direction. Is difficult.

  Accordingly, the first semiconductor laser element 310 and the second semiconductor laser element 320 are bonded together in a state where the cleavage directions of the first semiconductor laser element 310 and the second semiconductor laser element 320 do not coincide with each other. There is a case. In this case, the cleavage property when the resonator end faces (light emitting surfaces) of the first semiconductor laser element 310 and the second semiconductor laser element 320 are simultaneously formed by cleavage is lowered. As a result, the characteristics of the laser beam emitted from the resonator end face (light emitting surface) are degraded.

  In the conventional integrated semiconductor laser element shown in FIG. 25, the light emitting point 314 of the first semiconductor laser element 310 and the light emitting point 324 of the second semiconductor laser element 320 are spaced apart from each other in the horizontal direction. The semiconductor layers are also arranged at a predetermined interval in the stacking direction of the semiconductor layers. That is, the light emission point 314 of the first semiconductor laser element 310 and the light emission point 324 of the second semiconductor laser element 320 are separated in two directions, the horizontal direction and the stacking direction. For this reason, the space | interval of the light emission point 314 and the light emission castle 324 becomes large. As described above, when the distance between the light emitting point 314 and the light emitting point 324 is increased, the light emitting point 314 is used when the light emitted from the integrated semiconductor laser element is incident on an optical system (lens, mirror, etc.). Even if the optical axis is adjusted so that the light emitted from one of 324 and 324 enters the predetermined area of the optical system, the light emitted from the other of the light emitting points 314 and 324 is out of the predetermined area of the optical system. In some cases. As a result, since it is difficult to adjust the optical axis of the emitted light with respect to the optical system, the cost for adjusting the optical axis increases.

  On the other hand, in an integrated semiconductor laser element in which a plurality of semiconductor laser elements are stacked, if the method of applying a voltage to the electrodes of the plurality of semiconductor laser elements is limited, the method of using the integrated semiconductor laser element is limited. Therefore, in the integrated semiconductor laser element, it is desired that the degree of freedom in applying a voltage to the electrodes of the plurality of semiconductor laser elements is high.

  An object of the present invention is to provide an integrated semiconductor laser device in which the characteristics of laser light are improved, the cost for optical axis adjustment is reduced, and the degree of freedom in applying a voltage is high.

(1)
An integrated semiconductor laser element according to a first invention includes a first semiconductor laser element and a second semiconductor laser element stacked on the first semiconductor laser element with an insulating film interposed therebetween. The semiconductor laser device includes: a first substrate; a first semiconductor layer formed on one surface of the first substrate and having a first light emitting point that emits laser light having a first wavelength; A second semiconductor laser element comprising: a first electrode formed on the other surface of the substrate; and a second electrode formed on the first semiconductor layer. A second semiconductor layer formed on one surface of the substrate and having a second light emitting point that emits a laser beam having a second wavelength; and a third electrode formed on the other surface of the second substrate; , A fourth electrode formed on the second semiconductor layer, and the first semiconductor laser element includes the first semiconductor layer The second semiconductor laser element has the other of the concave part and the convex part on the second semiconductor layer side, and the insulating film is the second electrode of the first semiconductor laser element. Between the first semiconductor laser element and the fourth electrode of the second semiconductor laser element, and one of the convex part and the concave part of the first semiconductor laser element is fitted into the other of the concave part and the convex part of the second semiconductor laser element. It is a combination.

  In this integrated semiconductor laser element, the first semiconductor laser element has one of a convex part and a concave part on the first semiconductor layer side, and the second semiconductor laser element has a concave part on the second semiconductor layer side. And one of the convex portion and the concave portion of the first semiconductor laser element is fitted to the other of the concave portion and the convex portion of the second semiconductor laser element.

  Thereby, the interval between the first light emitting point of the first semiconductor layer and the second light emitting point of the second semiconductor layer is reduced. In addition, when the first semiconductor laser element and the second semiconductor laser element are stacked, the first and second semiconductor laser elements are displaced in the horizontal direction (direction parallel to one surface of the first substrate). Can be prevented. Accordingly, it is possible to prevent the optical axis of the emitted light from the first semiconductor laser element and the optical axis of the emitted light from the second semiconductor laser element from shifting in the horizontal direction. When the outgoing light is incident on an optical system (lens, mirror, etc.) and used, the optical axis of the outgoing light with respect to the optical system can be easily adjusted. As a result, the cost for adjusting the optical axis can be reduced.

  Furthermore, since the insulating film is disposed between the second electrode of the first semiconductor laser element and the fourth electrode of the second semiconductor laser element, the second electrode and the fourth electrode are electrically Separated. Thereby, arbitrary voltages can be applied to the second and fourth electrodes, respectively, using the first and third electrodes as a common electrode. In addition, any voltage can be applied to the first and third electrodes using the second and fourth electrodes as a common electrode. Furthermore, the first, second, third and fourth electrodes can be connected in any manner. In addition, an arbitrary voltage can be applied to each of the first, second, third, and fourth electrodes. As described above, the degree of freedom in applying a voltage to the first semiconductor laser element and the second semiconductor laser element is increased. As a result, the method of using the integrated semiconductor laser device is diversified.

(2)
The second semiconductor laser element has first and second through holes, a first extraction electrode extending from the second electrode through the first through hole to the other surface of the second substrate, and a fourth And a second extraction electrode extending from the other electrode to the other surface of the second substrate through the second through hole.

  In this case, the second and fourth electrodes are disposed between the first semiconductor laser element and the second semiconductor laser element. Since the first and second extraction electrodes respectively extend from the first and second electrodes to the other surface of the second substrate through the first and second through holes, respectively, the second from the other surface of the second substrate. In addition, electrical connection can be easily made to the fourth electrode. As a result, a voltage can be easily applied to the second electrode of the first semiconductor laser element and the fourth electrode of the second semiconductor laser element.

(3)
The convex portion and the concave portion may be provided so that the first light emitting point and the second light emitting point are located on a line in a direction perpendicular to one surface of the first substrate.

  Thereby, the interval between the first light emission point and the second light emission point is minimized. Accordingly, the deviation between the optical axis of the emitted light from the first light emitting point of the first semiconductor laser element and the optical axis of the emitted light from the second light emitting point of the second semiconductor laser element is reduced, and the optical system It becomes easy to adjust the optical axis of the emitted light with respect to. As a result, the cost for adjusting the optical axis can be further reduced.

(4)
The convex portion and the concave portion may be formed so as to extend in parallel with the emission direction of the laser light having the first or second wavelength.

  Thereby, the area | region where a convex part and a recessed part fit becomes long. As a result, it is possible to reliably prevent displacement of the first semiconductor laser element and the second semiconductor laser element in the horizontal direction.

(5)
The first semiconductor layer includes a first cladding layer, a first active layer, and a second cladding layer in order, and the second cladding layer includes a flat portion and a ridge portion extending in a stripe shape on the flat portion. The second semiconductor layer includes a third clad layer, a second active layer, and a fourth clad layer in order, and the fourth clad layer has a flat portion and stripes on the flat portion. And one of the convex portion and the concave portion is provided on the ridge portion of the second cladding layer, and the other of the concave portion and the convex portion is provided on the ridge portion of the fourth cladding layer. Also good.

  The first light emitting point is formed at the position of the first active layer near the ridge portion of the first semiconductor laser element, and the second light emitting point is the second active layer near the ridge portion of the second semiconductor laser element. It is formed at the position. Accordingly, the first light emitting point is located in the vicinity of one of the convex portion and the concave portion, and the second light emitting point is located in the vicinity of the other of the concave portion and the convex portion. Therefore, the interval between the first light emitting point and the second light emitting point is further reduced by fitting the convex portion and the concave portion.

(6)
The first semiconductor laser element has first and second regions, and the second semiconductor laser element is stacked on the first region of the first semiconductor laser element, and the first semiconductor laser element A third semiconductor laser element stacked on the region 2 with an insulating film interposed therebetween, the third semiconductor laser element being formed on the third substrate and one surface of the third substrate and Formed on the third semiconductor layer, a third semiconductor layer having a third emission point that emits laser light having a wavelength of 3, a fifth electrode formed on the other surface of the third substrate, and And a sixth electrode.

  In this case, an integrated semiconductor laser element having a structure in which the second semiconductor laser element and the third semiconductor laser element are respectively stacked on the first semiconductor laser element is formed. As a result, the laser light having the first, second and third wavelengths can be emitted from the integrated semiconductor laser element.

  Furthermore, since the second and third semiconductor laser elements are stacked on the first semiconductor laser element via an insulating film, the second, fourth and sixth electrodes are electrically separated. Thereby, an arbitrary voltage can be applied to the second, fourth and sixth electrodes with the first, third and fifth electrodes as common electrodes. In addition, any voltage can be applied to the first, third and fifth electrodes with the second, fourth and sixth electrodes as common electrodes. Furthermore, the first, second, third, fourth, fifth and sixth electrodes can be connected in any manner. Also, any voltage can be applied to each of the first, second, third, fourth, fifth and sixth electrodes. As described above, the degree of freedom in applying the voltage to the first, second, and third semiconductor laser elements is increased. As a result, the method of using the integrated semiconductor laser device is diversified.

(7)
The third semiconductor laser element may further include a third extraction electrode having a third through hole and extending from the sixth electrode to the other surface of the third substrate through the third through hole.

  In this case, the sixth electrode is disposed between the first semiconductor laser element and the third semiconductor laser element. Since the third extraction electrode extends from the sixth electrode to the other surface of the third substrate through the third through hole, an electrical connection can easily be made from the other surface of the third substrate to the sixth electrode. Can do. As a result, a voltage can be easily applied to the sixth electrode of the third semiconductor laser element.

(8)
The second substrate and the third substrate may be a common substrate. In this case, the second and third semiconductor laser elements are integrated by the common substrate. Accordingly, one of the convex portion and the concave portion of the first semiconductor laser element is fitted to the other of the concave portion and the convex portion of the second semiconductor laser element, thereby moving the first and second semiconductor laser elements in the horizontal direction. Can be prevented, and also the displacement of the third semiconductor laser element in the horizontal direction can be prevented.

(9)
According to a second aspect of the present invention, there is provided a method for manufacturing an integrated semiconductor laser device comprising: a step of forming a first semiconductor laser device; a step of forming a second semiconductor laser device; and an insulating film on the first semiconductor laser device. A step of stacking a second semiconductor laser element through the first step, and the step of forming the first semiconductor laser element includes: a first laser beam emitting a first wavelength on one surface of the first substrate; A step of forming a first semiconductor layer having a light emitting point, a step of forming one of a convex portion and a concave portion in the first semiconductor layer, and on the other surface of the first substrate and on the first semiconductor layer Forming a second semiconductor laser element, wherein the step of forming the second semiconductor laser element includes: a second laser beam that emits laser light having a second wavelength on one surface of the second substrate; Forming a second semiconductor layer having a light emitting point; and second semiconductor Forming the other of the concave portion and the convex portion, and forming a third electrode and a fourth electrode on the other surface of the second substrate and on the second semiconductor layer, respectively. The step of laminating the second semiconductor laser element on the element via the insulating film includes the step of laminating the insulating film between the second electrode of the first semiconductor laser element and the fourth electrode of the second semiconductor laser element. A step of fitting one of the convex portion and the concave portion of the first semiconductor laser element to the other of the concave portion and the convex portion of the second semiconductor laser element so as to be arranged is included.

  In this method of manufacturing an integrated semiconductor laser device, one of a convex portion and a concave portion is formed on the first semiconductor layer side of the first semiconductor laser device, and on the second semiconductor layer side of the second semiconductor laser device. The other of the concave portion and the convex portion is formed, and one of the convex portion and the concave portion of the first semiconductor laser element is fitted to the other of the concave portion and the convex portion of the second semiconductor laser element.

  Thereby, the interval between the first light emitting point of the first semiconductor layer and the second light emitting point of the second semiconductor layer is reduced. In addition, when the first semiconductor laser element and the second semiconductor laser element are stacked, the first and second semiconductor laser elements are displaced in the horizontal direction (direction parallel to one surface of the first substrate). Can be prevented. Accordingly, it is possible to prevent the optical axis of the outgoing light from the first semiconductor laser cord and the optical axis of the outgoing light from the second semiconductor laser element from being shifted in the horizontal direction, so that the integrated semiconductor laser element When the incident light is incident on an optical system (such as a lens and a mirror), the optical axis of the emitted light can be easily adjusted with respect to the optical system. As a result, the cost for adjusting the optical axis can be reduced.

  Further, since the first semiconductor laser element and the second semiconductor laser element can be prevented from being displaced in the horizontal direction when the first semiconductor laser element and the second semiconductor laser element are stacked, the first semiconductor laser element and the second semiconductor laser element can be prevented. Prevents the first semiconductor laser element and the second semiconductor laser element from being displaced from each other when the resonator end faces (light emitting surfaces) of the semiconductor laser element and the second semiconductor laser element are formed by cleavage. be able to. Thereby, the cleavage property of the first and second semiconductor laser elements can be improved. As a result, the characteristics of the laser beam can be improved.

  Furthermore, since the insulating film is disposed between the second electrode of the first semiconductor laser element and the fourth electrode of the second semiconductor laser element, the second electrode and the fourth electrode are electrically Separated. Thereby, arbitrary voltages can be applied to the second and fourth electrodes, respectively, using the first and third electrodes as a common electrode. In addition, any voltage can be applied to the first and third electrodes using the second and fourth electrodes as a common electrode. Furthermore, the first, second, third and fourth electrodes can be connected in any manner. In addition, an arbitrary voltage can be applied to each of the first, second, third, and fourth electrodes. As described above, the degree of freedom in applying a voltage to the first semiconductor laser element and the second semiconductor laser element is increased. As a result, the method of using the integrated semiconductor laser device is diversified.

(10)
The manufacturing method of the integrated semiconductor laser device includes the first semiconductor laser in a state where one of the convex portion and the concave portion of the first semiconductor laser element is fitted to the other of the concave portion and the convex portion of the second semiconductor laser element. A step of simultaneously cleaving the element and the second semiconductor laser element may be further included.

  As a result, it is possible to prevent the horizontal displacement of the first semiconductor laser element and the second semiconductor laser element when the first semiconductor laser element and the second semiconductor laser element are stacked. Preventing the cleavage directions of the first semiconductor laser element and the second semiconductor laser element from deviating from each other when the resonator end faces (light emitting surfaces) of the first semiconductor laser element and the second semiconductor laser element are formed by cleavage. can do. Therefore, the cleavage property of the first and second semiconductor laser elements can be improved. As a result, the characteristics of the laser beam can be improved.

(11)
The manufacturing method of the integrated semiconductor laser device further includes a step of forming a third semiconductor laser device, and the step of forming the second semiconductor layer includes forming a second region on the first region of one surface of the second substrate. The step of forming a third semiconductor laser element includes a step of forming a semiconductor layer, and a step of forming a third light emitting point that emits a laser beam of a third wavelength in a second region of one surface of the second substrate. Forming a third semiconductor layer having, and forming fifth and sixth electrodes on a region of the second substrate and on the third semiconductor layer on the opposite side of the third semiconductor layer, respectively. May be included.

  In this case, an integrated semiconductor laser element having a structure in which the second semiconductor laser element and the third semiconductor laser element are respectively stacked on the first semiconductor laser element is formed. As a result, the laser light having the first, second and third wavelengths can be emitted from the integrated semiconductor laser element.

  Further, the second semiconductor laser element and the third laser element are integrally formed on the second substrate. Thereby, one of the convex portion and the concave portion of the first semiconductor laser element is fitted to the other of the concave portion and the convex portion of the second semiconductor laser element, thereby moving the first and second semiconductor laser elements in the horizontal direction. Can be prevented, and also the displacement of the third semiconductor laser element in the horizontal direction can be prevented.

  Furthermore, since the second and third semiconductor laser elements are stacked on the first semiconductor laser element via an insulating film, the second, fourth and sixth electrodes are electrically separated. Thereby, an arbitrary voltage can be applied to the second, fourth and sixth electrodes with the first, third and fifth electrodes as common electrodes. In addition, any voltage can be applied to the first, third and fifth electrodes with the second, fourth and sixth electrodes as common electrodes. Furthermore, the first, second, third, fourth, fifth and sixth electrodes can be connected in any manner. Also, any voltage can be applied to each of the first, second, third, fourth, fifth and sixth electrodes. As described above, the degree of freedom in applying the voltage to the first, second, and third semiconductor laser elements is increased. As a result, the method of using the integrated semiconductor laser device is diversified.

(12)
The manufacturing method of the integrated semiconductor laser device includes the first semiconductor laser in a state where one of the convex portion and the concave portion of the first semiconductor laser element is fitted to the other of the concave portion and the convex portion of the second semiconductor laser element. A step of simultaneously cleaving the element, the second semiconductor laser element, and the third semiconductor laser element may be further included.

  This prevents the horizontal displacement between the first semiconductor laser element and the second and third semiconductor laser elements when the first semiconductor laser element and the second and third semiconductor laser elements are stacked. Therefore, the first, second, and third semiconductor laser elements, the second semiconductor laser element, and the third semiconductor laser element can be formed by cleaving to form the cavity end faces (light emitting surfaces). It is possible to prevent the cleavage directions of the semiconductor laser elements from deviating from each other. Therefore, the cleavage property of the first, second and third semiconductor laser elements can be improved. As a result, the characteristics of the laser beam can be improved.

  According to the present invention, the characteristics of laser light are improved, the cost for adjusting the optical axis is reduced, and the degree of freedom in applying a voltage is increased.

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

(1) First embodiment (a) Overall schematic structure of integrated semiconductor laser device FIG. 1A is a schematic cross-sectional view showing the structure of an integrated semiconductor laser device according to a first embodiment of the present invention. FIG. 1B is a plan view showing the upper surface of FIG. FIG. 1A is a cross-sectional view taken along line 100-100 in FIG. With reference to FIGS. 1A and 1B, the structure of the integrated semiconductor laser device according to the first embodiment will be described.

  In FIG. 1, two directions parallel to and perpendicular to the surface of an n-type GaN substrate 1 described later are defined as an X direction and a Y direction, and a direction perpendicular to the X direction and the Y direction is defined as a Z direction.

  As shown in FIG. 1A, the integrated semiconductor laser device according to the first embodiment is a semiconductor laser device that emits blue-violet laser light having a convex portion for alignment (hereinafter, blue-violet laser). 110) and a semiconductor laser element (hereinafter, referred to as a red laser element) 120 that emits red laser light having a concave portion for alignment are stacked (integrated) in the Z direction.

(B) Structure of Blue-violet Laser Element 110 First, the structure of the blue-violet laser element 110 in FIG. 1 will be described. FIG. 2 is a detailed sectional view of the blue-violet laser element 110 of FIG. As shown in FIG. 2, an n-type cladding layer 2 made of n-type AlGaN having a thickness of about 2.5 μm is formed on an n-type GaN substrate 1. An active layer 3 having a thickness of about 70 nm is formed on the n-type cladding layer 2. The active layer 3 has an MQW (Multiple Quantum Well) structure in which a plurality of well layers made of undoped InGaN and a plurality of barrier layers made of undoped InGaN are alternately stacked.

  On the active layer 3, an optical guide layer 4 made of undoped InGaN having a thickness of about 80 nm is formed. A cap layer 5 made of undoped AlGaN having a thickness of about 20 nm is formed on the light guide layer 4.

  On the cap layer 5, a p-type cladding layer 6 made of p-type AlGaN having a flat portion and a convex portion thereon is formed. The thickness of the flat portion of the p-type cladding layer 6 is about 50 nm, and the height from the upper surface of the flat portion of the convex portion is about 350 nm. A p-type contact layer 7 made of p-type InGaN having a thickness of about 3 nm is formed on the convex portion of the p-type cladding layer 6. The p-type contact layer 7 and the convex portion of the p-type cladding layer 6 constitute a ridge portion 8.

  Here, in the first embodiment, the ridge portion 8 has a tapered side surface such that the width of the upper end is smaller than the width of the lower end. The angle θ1 formed between the side surface of the ridge 8 and the upper surface of the active layer 3 is about 70 °. The width of the upper end of the ridge portion 8 is about 1.5 μm. The ridge portion 8 is formed in a stripe shape (elongated shape) extending in a direction (Y direction) orthogonal to the light emitting surface (cleavage surface) 102 shown in FIG.

  Further, as shown in FIG. 2, the portion of the active layer 3 below the ridge portion 8 becomes the light emission point 13 of the blue-violet laser element 110.

A current blocking layer 9 made of a SiO ₂ film having a thickness of about 200 nm is formed so as to cover the side surface of the ridge portion 8 and the upper surface of the flat portion of the p-type cladding layer 6. A p-side electrode 10 is formed on the current block layer 9 so as to be in contact with the upper surface of the ridge portion 8 (p-type contact layer 7). The p-side electrode 10 is composed of a Pd layer having a thickness of about 100 nm and an Au layer having a thickness of about 1 μm in this order from the n-type GaN substrate 1 side.

  Thereby, the convex part 18 for alignment including the ridge part 8 is comprised. The height of the convex portion 18 for alignment (the height from the upper surface of the p-side electrode 10 located on the upper surface of the flat portion of the p-type cladding layer 6 to the upper surface of the p-side electrode 10 located on the upper surface of the ridge portion 8) H) H1 is about 153 nm.

  An n-side electrode 11 is formed on the back surface of the n-type GaN substrate 1. The n-side electrode 11 is composed of an Al layer having a thickness of about 6 nm, a Pd layer having a thickness of about 10 nm, and an Au layer having a thickness of about 300 nm in this order from the n-type GaN substrate 1 side. Hereinafter, the n-type cladding layer 2, the active layer 3, the light guide layer 4, the cap layer 5, and the p-type cladding layer 6 are referred to as an element constituent layer a.

(C) Structure of Red Laser Element 120 Next, the structure of the red laser element 120 in FIG. 1 will be described. FIG. 3 is a detailed cross-sectional view of the red laser element 120 of FIG.

  As shown in FIG. 3, an n-type buffer layer 22 made of n-type GaInP having a thickness of about 300 nm is formed on an n-type GaAs substrate 21. An n-type cladding layer 23 made of n-type AlGaInP having a thickness of about 2 μm is formed on the n-type buffer layer 22. On the n-type cladding layer 23, an active layer 24 having a thickness of about 60 nm is formed. The active layer 24 has an MQW structure in which a plurality of well layers made of undoped GaInP and a plurality of barrier layers made of undoped AlGaInP are alternately stacked.

  A p-type first cladding layer 25 made of p-type AlGaInP having a thickness of about 300 nm is formed on the active layer 24. In a predetermined region on the p-type first cladding layer 25, a convex p-type second cladding layer 26 made of p-type AlGaInP having a thickness of about 1.2 μm is formed. A p-type intermediate layer 27 made of p-type GaInP having a thickness of about 100 nm is formed on the p-type second cladding layer 26.

  A p-type contact layer 28 made of p-type GaAs having a thickness of about 300 nm is formed on the p-type intermediate layer 27. The p-type contact layer 28, the p-type intermediate layer 27, and the p-type second cladding layer 26 constitute a ridge portion 29 having a tapered side surface whose width decreases from the lower end toward the upper end. An angle θ2 formed between the side surface of the ridge portion 29 and the surface of the active layer 24 (p-type first cladding layer 25) is about 60 °. The width of the upper end of the ridge portion 29 is about 2.7 μm.

  The ridge portion 29 is formed in a stripe shape (elongated shape) extending in a direction (Y direction) orthogonal to the light emitting surface (cleavage surface) 102 shown in FIG. As shown in FIG. 3, the portion of the active layer 24 below the ridge portion 29 becomes the light emission point 34 of the red laser element 120.

  Here, in the first embodiment, a thickness (about 2 μm) larger than the height (about 1.6 μm) of the ridge portion 29 so as to cover the side surface of the ridge portion 29 on the p-type first cladding layer 25. ) Having an n-type current blocking layer 30 is formed. The n-type current blocking layer 30 has an opening 30a through which the surface of the ridge 29 is exposed. The opening 30a of the n-type current blocking layer 30 has a tapered shape such that the width of the upper end (about 3 μm) is larger than the width of the bottom (the width of the upper end of the ridge portion 29 (about 2.7 μm)). It has a side.

  The angle θ3 formed by the inner surface of the opening 30a of the n-type current blocking layer 30 and the surface of the active layer 24 is about 70 °. Further, the opening 30 a of the n-type current blocking layer 30 is formed in a stripe shape (elongated shape) extending in the Y direction along the ridge portion 29 as shown in FIG. The n-type current blocking layer 30 includes an n-type AlInP layer and an n-type GaAs layer in order from the n-type GaAs substrate 21 side.

  A p-side electrode 31 having a thickness of about 0.3 μm is formed in a region including the opening 30a on the n-type current blocking layer 30 (p-type contact layer 28). The p-side electrode 31 is composed of an AuZn layer, a Pt layer, and an Au layer in this order from the n-type GaAs substrate 21 side. A positioning recess 38 is formed in the p-side electrode 31 that covers the opening 30 a of the n-type current blocking layer 30. As a result, the depth of the alignment recess 38 (corresponding to the depth from the upper surface of the n-type current blocking layer 30 to the upper surface of the p-type contact layer 28) D1 is about 400 nm. That is, the depth D1 (about 400 nm) of the alignment recess 38 is larger than the height H1 (153 nm) of the alignment protrusion 18.

  An n-side electrode 32 having a thickness of about 1 μm is formed on the back surface of the n-type GaAs substrate 21. The n-side electrode 32 includes an AuGe layer, an Ni layer, and an Au layer in order from the n-type GaAs substrate 21 side. Hereinafter, the n-type buffer layer 22, the n-type cladding layer 23, the active layer 24, the p-type first cladding layer 25, the p-type second cladding layer 26, the p-type intermediate layer 27, and the p-type contact layer 28 will be referred to as an element configuration layer b. Call it.

(D) Overall Detailed Structure of Integrated Semiconductor Laser Element Here, the overall configuration of the integrated semiconductor laser element according to the present embodiment will be described with reference to FIG.

  As shown in FIG. 1A, after forming the insulating film 12 and the solder layers 115a and 115b made of Au—Sn on the blue-violet laser element 110 having the structure of FIG. 2, the blue-violet laser element of FIG. The blue-violet laser element 110 and the red laser element 120 are joined so that the alignment convex part 110 of 110 is fitted into the alignment concave part 38 of the red laser element 120 of FIG. In this case, the insulating film 33 is formed on the bonding surface of the red laser element 120.

  The n-side electrode 11 of the blue-violet laser element 110 is bonded on the conductive submount 500. The solder layer 115a and the solder layer 115b are electrically separated from each other by the insulating films 12 and 33.

  The emission point 13 of the blue-violet laser element 110 and the emission point 34 of the red laser element 120 are arranged on the same line in the stacking direction (Z direction) of the semiconductor layers. As described above, the depth D1 (about 400 nm) of the alignment recess 38 of the red laser element 120 is greater than the height H1 (153 nm) of the alignment protrusion 18 of the blue-violet laser element 110. Therefore, the distance between the upper surface of the alignment convex portion 18 of the blue-violet laser element 110 and the bottom surface of the alignment concave portion 38 of the red laser element 120 is the alignment convex portion of the blue-violet laser element 110. The distance between the region other than 18 and the region other than the concave portion 38 for alignment of the red laser element 120 is larger.

  In addition, circular through-holes 120 a and 120 b that penetrate the n-type GaAs substrate 21, the element configuration layer b, the n-type current blocking layer 30, and the p-side electrode 31 are formed. The through hole 120a and the through hole 120b have a tapered inner surface whose diameter on the n-side electrode 32 side is several tens of μm, and whose diameter on the p-side electrode 31 side is smaller than the diameter on the n-side electrode 32 side. Have

An insulating film 35 made of a SiO ₂ film having a thickness of about 200 nm is formed so as to extend from the inner side surface of through hole 120a and the inner side surface of through hole 120b onto a partial region of n-side electrode 32.

  An external connection electrode 36a having a thickness of about 0.3 μm is formed on the inner surface of the through hole 120a and the region on the insulating film 35 on the n-side electrode 32 so as to be electrically connected to the solder layer 115a. Has been. The external connection electrode similar to the external connection electrode 36a is electrically connected to the solder layer 115b on the inner surface of the through hole 120b and the region on the insulating film 35 on the n-side electrode 32. 36b is formed. The external connection electrode 36a and the external connection electrode 36b are composed of a Ti layer, a Pt layer, and an Au layer in this order from the n-type GaAs substrate 21 side.

  One end of a wire 122 a made of a gold wire or the like is bonded to the n-side electrode 32, and the other end of the wire 122 a is bonded to the conductive submount 500. A wire 122b is bonded to the external connection electrode 36a, and a wire 122c is bonded to the external connection electrode 36b.

  In this case, the p-side electrode 31 of the red laser element 110 is electrically connected to the external connection electrode 36a via the solder layer 115a. The p-side electrode 10 of the blue-violet laser element 110 is electrically connected to the external connection electrode 36b through the solder layer 115b.

(E) Effects of the First Embodiment In the first embodiment, as described above, the alignment convex portion 18 is fitted into the alignment concave portion 38 to thereby adjust the alignment convexity. The blue-violet laser element 110 and the red laser element 120 are stacked in the horizontal direction (FIG. 1 (a) in the X direction) when the blue-violet laser element 110 and the red laser element 120 are stacked. Misalignment can be prevented. Thereby, it is possible to prevent the optical axis of the emitted light from the blue-violet laser element 110 and the optical axis of the emitted light from the red laser element 120 from being shifted in the horizontal direction (X direction in FIG. 1A). Therefore, it becomes easy to adjust the optical axis of the emitted light with respect to the optical system when the emitted light of the integrated semiconductor laser element is made incident on the optical system (lens, mirror, etc.). Therefore, the cost for adjusting the optical axis can be reduced.

  Further, it is possible to prevent the positional deviation of the blue-violet laser element 110 and the red laser element 120 in the horizontal direction (X direction in FIG. 1A) when the blue-violet laser element 110 and the red laser element 120 are stacked. Therefore, it is possible to prevent the cleavage directions of the blue-violet laser element 110 and the red laser element 120 from being shifted from each other. Thereby, after the blue-violet laser element 110 and the red laser element 120 are bonded together, a cleavage property when the blue-violet laser element 110 and the red laser element 120 are simultaneously cleaved to form a light emitting surface which is a cavity end face. Can be improved. As a result, the characteristics of the laser beam emitted from the light emitting surface (cleavage surface) 102 can be improved.

  Further, the p-side electrode 10 of the blue-violet laser element 110 and the p-side electrode 31 of the red laser element 120 are electrically separated through the insulating film 12 and the insulating film 33. Thereby, the n-side electrode 11 of the blue-violet laser element 110 and the n-side electrode 32 of the red laser element 120 can be used as a common electrode. In this case, an arbitrary voltage can be applied to the p-side electrode 10 of the blue-violet laser element 110 and the p-side electrode 31 of the red laser element 120, respectively.

  Further, the external connection electrode 36a and the external connection electrode 36b are connected by a wire, and the wires are bonded to the n-side electrode 32 and the conductive submount 500 of the red laser element 120, respectively. The p-side electrode 10 and the p-side electrode 31 of the red laser element 120 can be used as a common electrode. In this case, an arbitrary voltage can be applied to the n-side electrode 11 of the blue-violet laser element 110 and the n-side electrode 32 of the red laser element 120, respectively.

  Further, the p-side electrode 10 of the blue-violet laser element 110 and the n-side electrode 32 of the red laser element 120 can be electrically connected, and the n-side electrode 11 of the blue-violet laser element 110 and the p-side electrode of the red laser element 120 can be connected. The side electrode 31 can also be electrically connected.

  In the first embodiment, the emission point 13 of the blue-violet laser element 110 and the emission point 34 of the red laser element 120 are on the same line in the stacking direction of the semiconductor layers (Z direction in FIG. 1A). By arranging them, the emission point 13 of the blue-violet laser element 110 and the emission point 34 of the red laser element 120 are arranged in two directions (the stacking direction of the semiconductor layers (Z direction in FIG. 1A)) and in the horizontal direction (FIG. 1 ( Compared with the case of shifting to the X direction of a))), the distance between the emission point 13 of the blue-violet laser element 110 and the emission point 34 of the red laser element 120 can be reduced. As a result, when the emitted light of the integrated semiconductor laser element is incident on an optical system (lens, mirror, etc.) and used, the emission point 13 from the blue-violet laser element 110 and the emission point 34 from the red laser element 120 are used. When the optical axis is adjusted so that the emitted light is incident on a predetermined region of the optical system, the light emitted from the other of the emission point 13 of the blue-violet laser element 110 and the emission point 34 of the red laser element 120 is optical. It is possible to prevent the light from entering a region greatly deviating from a predetermined region of the system. As a result, the optical axis adjustment with respect to the optical system becomes easier, so that the cost for the optical axis adjustment can be further reduced.

  In the first embodiment, the convex portion 18 (ridge portion 8) for alignment of the blue-violet laser element 110 extends in a direction perpendicular to the light emitting surface 102 (Y direction in FIG. 1B). In this way, the concave portion 38 for alignment of the red laser element 120 (the opening 30a of the n-type current blocking layer 30) is formed in a direction perpendicular to the light emitting surface 102 (FIG. 1 ( b) in a stripe shape (elongated shape) rather than extending in the Y direction), the region where the alignment convex portion 18 and the alignment concave portion 38 are fitted to the light emitting surface 102. It becomes longer in the orthogonal direction (Y direction in FIG. 1B). Thus, it is possible to prevent the horizontal displacement (X direction in FIG. 1B) of the blue-violet laser element 110 and the red laser element 120 when the blue-violet laser element 110 and the red laser element 120 are stacked. it can.

  In the first embodiment, the alignment convex portion 18 of the blue-violet laser element 110 is formed so as to have a tapered shape such that the upper end width is smaller than the lower end width, and the red laser By forming the concave portion 38 of the element 120 so as to have a tapered shape such that the width of the lower end is smaller than the width of the upper end, the alignment convex portion 18 can be easily fitted into the alignment concave portion 38. be able to.

  In the first embodiment, the alignment convex portion 18 of the blue-violet laser element 110 and the alignment concave portion 38 of the red laser element 120 are joined via the solder layer 115a and the solder layer 115b. Accordingly, the alignment convex portion 18 of the blue-violet laser element 110 and the alignment concave portion 38 of the red laser element 120 can be easily joined by the solder layer 115a and the solder layer 115b.

  In the first embodiment, the distance between the upper surface of the alignment convex portion 18 of the blue-violet laser element 110 and the bottom surface of the alignment concave portion 38 of the red laser element 120 is the blue-violet laser element 110. The alignment convex portion 18 of the blue-violet laser element 110 is made larger than the distance between the region other than the alignment convex portion 18 and the region other than the alignment concave portion 38 of the red laser element 120. Even if a region other than the above and a region other than the alignment recess 38 of the red laser element 120 are in contact, the upper surface of the alignment projection 18 and the bottom surface of the alignment recess 38 are in contact with each other. Can be prevented. This prevents the ridges 8 and 29 from being stressed when the alignment convex portion 18 of the blue-violet laser element 110 and the alignment concave portion 38 of the red laser element 120 are joined. it can.

  In the first embodiment, since the n-type current blocking layer 30 of the red laser element 120 is made of n-type GaAs having good heat dissipation characteristics, the heat dissipation characteristics of the integrated semiconductor laser element can be improved. .

(F) Manufacturing Method of Integrated Semiconductor Laser Device FIGS. 4 to 7 and FIGS. 9 to 13 are process cross-sectional views for explaining the manufacturing method of the integrated semiconductor laser device of FIG. Next, with reference to FIGS. 1-13, the manufacturing method of the integrated semiconductor laser element by 1st Embodiment is demonstrated. FIG. 8 is a plan view showing the n-side electrode and the p-side electrode of the blue-violet laser element 110, respectively.

  In the first embodiment, the blue-violet laser element 110 is formed by the steps shown in FIGS. 4A to 7J, and the steps shown in FIGS. 9A to 12M are performed. Then, the red laser element 120 is formed.

(F-1) Method for Forming Blue-violet Laser Element 110 When forming the blue-violet laser element 110, first, as shown in FIG. 4A, an element configuration layer a is formed on an n-type GaN substrate 1. Form (see FIG. 2). Specifically, an n-type having a thickness of about 2.5 μm is formed on an n-type GaN substrate 1 having a thickness of about 400 μm by using MOCVD (Metal Organic Chemical Vapor Deposition) method. After growing the n-type cladding layer 2 made of AlGaN, an active layer 3 having a thickness of about 70 nm is grown on the n-type cladding layer 2. When the active layer 3 is grown, a plurality of well layers made of undoped InGaN and a plurality of barrier layers made of undoped InGaN are alternately grown. Thereby, the active layer 3 having an MQW structure in which a plurality of well layers and a plurality of barrier layers are alternately stacked is formed on the n-type cladding layer 2.

  Next, an optical guide layer 4 made of undoped InGaN having a thickness of about 80 nm and a cap layer 5 made of undoped AlGaN having a thickness of about 20 nm are sequentially grown on the active layer 3. Thereafter, a p-type cladding layer 6 made of p-type AlGaN having a thickness of about 400 nm is grown on the cap layer 5. In this way, the element configuration layer a is formed on the n-type GaN substrate 1. A p-type contact layer 7 made of p-type InGaN having a thickness of about 3 nm is grown on the element constituting layer a.

Next, as shown in FIG. 4B, an SiO ₂ film 14 having a thickness of about 240 nm is formed on the p-type contact layer 7 by plasma CVD. Thereafter, a striped (elongated) resist 15 having a width of about 1.5 μm is formed on the SiO ₂ film 14 in a region where the ridge portion 8 (see FIG. 1A) is to be formed in a later step. To do.

Next, as shown in FIG. 4C, the SiO ₂ film 14 is etched using the resist 15 as a mask by RIE (Reactive Ion Etching) using CF ₄ gas. Thereafter, the resist 15 is removed.

Next, as shown in FIG. 5D, the p-type cladding layer 6 in the element constituent layer a is formed from the upper surface of the p-type contact layer 7 using the SiO ₂ film 14 as a mask by using the RIE method using chlorine-based gas. Etching is performed to a depth in the middle of (see FIG. 2) (a depth of about 350 nm from the upper surface of the p-type cladding layer 6). Thereby, the ridge portion 8 constituted by the convex portion of the p-type cladding layer 6 and the p-type contact layer 7 is formed. At this time, the ridge portion 8 is formed to have a tapered side surface such that the width of the upper end is smaller than the width of the lower end. The angle θ1 formed between the side surface of the ridge portion 8 and the upper surface of the active layer 3 (p-type cladding layer 6) is about 70 °, and the width of the upper end of the ridge portion 8 is about 1.5 μm. Further, as shown in FIG. 1B, the ridge portion 8 is formed in a stripe shape (elongated shape) extending in a direction orthogonal to the light emitting surface 102. The ridge portion 8 becomes a convex portion 18 for alignment. Thereafter, the SiO ₂ film 14 is removed.

Next, as shown in FIG. 5E, a current block made of a SiO ₂ film having a thickness of about 200 nm so as to cover the entire surface of the p-type contact layer 7 and the element constituent layer a using plasma CVD. Layer 9 is formed. Thereafter, a resist 16 covering the entire surface of the current blocking layer 9 is formed.

Next, as shown in FIG. 5 (f), the resist 16 is etched (etched back) over the entire area by using a plasma etching technique using oxygen gas to be thinned and positioned on the upper surface of the ridge portion 8. The surface of the current blocking layer 9 is exposed. Thereafter, the current blocking layer 9 located on the upper surface of the ridge portion 8 is etched using the resist 16 as a mask by RIE using CF ₄ gas. As a result, the upper surface of the ridge 8 is exposed as shown in FIG. Thereafter, the resist 16 is removed.

  Next, as shown in FIG. 5H, the p-side electrode 10 is formed on the current blocking layer 9 so as to be in contact with the upper surface of the ridge portion 8 (p-type contact layer 7) by using an electron beam evaporation method. Form. At this time, a Pd layer having a thickness of about 100 nm and an Au layer having a thickness of about 1 μm are sequentially formed. Thus, the height of the alignment convex portion 18 (the upper surface of the p-side electrode 10 positioned on the upper surface of the ridge portion 8 from the upper surface of the p-side electrode 10 positioned on the upper surface of the flat portion of the p-type cladding layer 6). H1) is about 153 nm.

  In this case, as shown in FIG. 8A, the end of the p-side electrode 10 positioned on the side of the end face 1a parallel to the light emitting surface 102 (see FIG. 1B) of the n-type GaN substrate 1 is n The GaN substrate 1 is disposed in a region spaced a predetermined distance from the end face 1 a of the GaN substrate 1.

Next, as shown in FIG. 6 (i), the back surface of the n-type GaN substrate 1 is polished until the thickness from the upper surface of the ridge portion 8 to the back surface of the n-type GaN substrate 1 becomes about 150 μm. Further, an insulating film 12 made of a SiO ₂ film having a thickness of about 200 nm is formed on the p-side electrode 10 by using a plasma CVD method so that a partial region of the p-side electrode 10 except on the ridge portion 8 is exposed. To do.

  Next, as shown in FIG. 7J, an n-side electrode 11 is formed on the back surface of the n-type GaN substrate 1 by using an electron beam evaporation method. At this time, an Al layer having a thickness of about 6 nm, a Pd layer having a thickness of about 10 nm, and an Au layer having a thickness of about 300 nm are sequentially formed. In this way, the blue-violet laser element 110 of the first embodiment is formed.

  In this case, as shown in FIG. 8B, the end of the n-side electrode 11 positioned on the side of the end face 1a parallel to the light emitting surface 102 (see FIG. 1B) of the n-type GaN substrate 1 is n The GaN substrate 1 is disposed in a region spaced a predetermined distance from the end face 1 a of the GaN substrate 1. As a result, as shown in FIGS. 8A and 8B, the blue-violet laser element 110 and the red laser element 120 are laminated in the region where the p-side electrode 10 and the n-side electrode 11 are not formed. In this case, the ridge portion 8 of the blue-violet laser element 110 becomes a transparent region 111 that can be visually recognized from above or below.

  Thereafter, as shown in FIG. 7 (j), a solder layer 115 a is formed in a region on the insulating film 12 including the ridge portion 8, and a solder layer 115 b is formed on the exposed p-side electrode 10.

(F-2) Method of Forming Red Laser Element 120 Next, when forming the red laser element 120, first, as shown in FIG. 9A, the element constituent layer b is formed on the n-type GaAs substrate 21. (See FIG. 3). Specifically, an n-type buffer layer 22 made of n-type GaInP having a thickness of about 300 nm is grown on the n-type GaAs substrate 21 by MOCVD, and then about n-type buffer layer 22 is formed. An n-type cladding layer 23 made of n-type AlGaInP having a thickness of 2 μm is grown. Thereafter, an active layer 24 having a thickness of about 60 nm is grown on the n-type cladding layer 23. When the active layer 24 is grown, a plurality of well layers made of undoped GaInP and a plurality of barrier layers made of undoped AlGaInP are alternately grown. As a result, an active layer 24 having an MQW structure in which a plurality of well layers and a plurality of barrier layers are alternately stacked is formed on the n-type cladding layer 23.

  Next, a p-type first cladding layer 25 made of p-type AlGaInP having a thickness of about 300 nm and a p-type second cladding layer 26 made of p-type AlGaInP having a thickness of about 1.2 μm are sequentially formed on the active layer 24. Grow. Subsequently, a p-type intermediate layer 27 made of p-type GaInP having a thickness of about 100 nm is grown on the p-type second cladding layer 26, and then a p-type having a thickness of about 300 nm is formed on the p-type intermediate layer 27. A p-type contact layer 28 made of type GaAs is grown. In this way, the element configuration layer b is formed.

Next, as shown in FIG. 9B, a SiO ₂ film 35 having a thickness of about 240 nm is formed on the element constituent layer b by using a sputtering method, a vacuum evaporation method or an electron beam evaporation method. Thereafter, a striped (elongated) resist 116 having a width of about 2.7 μm is formed on the SiO ₂ film 35 in a region where the ridge 29 (see FIG. 1A) is to be formed in a later step. To do.

Next, as shown in FIG. 9C, the SiO ₂ film 35 is etched using the resist 116 as a mask by using a wet etching technique using buffered hydrofluoric acid. Thereafter, the resist 116 is removed.

Next, as shown in FIG. 9D, by using a wet etching technique using a tartaric acid-based etching solution or a phosphoric acid-based etching solution, using the SiO ₂ film 35 as a mask, the p-type contact layer 28 of the element constituent layer b is formed. Etching is performed from the upper surface to the upper surface of the p-type first cladding layer 25 (see FIG. 3). As a result, a ridge portion 29 having a tapered side surface is formed, including the p-type contact layer 28, the p-type intermediate layer 27, and the p-type second cladding layer 26. The angle θ2 formed between the side surface of the ridge portion 29 and the upper surface of the active layer 24 (p-type first cladding layer 25) is about 60 °, and the width of the upper end portion of the ridge portion 29 is about 2.7 μm. . Further, as shown in FIG. 1B, the ridge portion 29 is formed in a stripe shape (elongated shape) extending in a direction orthogonal to the light emitting surface 102.

Next, as shown in FIG. 10E, an n-type current blocking layer 30 having a thickness of about 2 μm is formed on the entire surface of the element constituent layer b by using the MOCVD method with the SiO ₂ film 35 as a selective growth mask. Form. In this case, an n-type AlInP layer and an n-type GaAs layer are sequentially formed. The n-type current blocking layer 30 is grown selectively on the upper surface of the element constituting layer b, and then grown laterally so as to cover the SiO ₂ film 35.

Next, as shown in FIG. 10F, a thickness of about 240 nm is formed on the n-type current blocking layer 30 except for the stripe-shaped (elongated) region above the ridge portion 29 by plasma CVD. An SiO ₂ film 37 having the following is formed. Next, the n-type current blocking layer 30 located above the upper surface of the ridge portion 29 is etched using the SiO ₂ film 37 as a mask by using a wet etching technique using a phosphoric acid-based etching solution. As a result, the n-type current blocking layer 30 having the opening 30a from which the upper surface of the SiO ₂ film 35 on the ridge 29 is exposed is formed. At this time, the opening 30a of the n-type current blocking layer 30 is formed to have a tapered inner surface such that the lower end width is smaller than the upper end width.

The angle θ3 formed by the inner side surface of the opening 30a of the n-type current blocking layer 30 and the upper surface of the active layer 24 (p-type contact layer 28) is about 70 °. The width of the upper end of the opening 30a of the n-type current blocking layer 30 is about 3 μm and the width of the lower end is about 2.7 μm. The opening 30 a of the n-type current blocking layer 30 is formed in a stripe shape (elongated shape) along the ridge portion 29. Thereafter, the SiO ₂ films 35 and 37 are removed.

  Next, as shown in FIG. 10G, a thickness of about 0.3 μm is formed so as to extend from the bottom surface of the opening 30a to a partial region on the n-type current blocking layer 30 by using an electron beam evaporation method. A p-side electrode 31 having the structure is formed. At this time, an AuZn layer and a Pt layer are sequentially formed. Thereby, the depth of the positioning recess 38 (depth from the upper surface of the p-side electrode 31 located on the upper surface of the current blocking layer 30 to the upper surface of the p-side electrode 31 located on the upper surface of the ridge portion 29). D1 is about 400 nm. That is, the depth D1 (about 400 nm) of the alignment recess 38 is larger than the height H1 (153 nm) of the alignment protrusion 18 (see FIG. 1A).

  Further, the back surface of the n-type GaAs substrate 21 is polished until the thickness from the upper surface of the ridge portion 29 to the back surface of the n-type GaAs substrate 21 becomes about 100 μm. Thereafter, by using an electron beam evaporation method, except for a region where the through hole 120a and the through hole 120b (see FIG. 1A) are to be formed in a later step on the back surface of the n-type GaAs substrate 21, the thickness is about 1 μm. An n-side electrode 32 having a thickness is formed. At this time, an AuGe layer, a Ni layer, and an Au layer are sequentially formed.

Next, as shown in FIG. 11H, an insulating film 33 made of a SiO ₂ film is formed on the n-type current blocking layer 30 on a region separated from the p-side electrode 31 by using a plasma CVD method.

  Next, as shown in FIGS. 11 (i) and 11 (j), the element constituent layer b is formed from the back surface of the n-type GaAs substrate 21 using the n-side electrode 32 as a mask by using the RIE method using chlorine-based gas. Then, a circular through hole 120 a penetrating the n-type current blocking layer 30 and the p-side electrode 31 is formed. Similarly, a circular through hole 120b penetrating the element constituent layer b, the n-type current blocking layer 30, and the insulating film 33 is formed from the back surface of the n-type GaAs substrate 21. The through hole 120a and the through hole 120b are formed to have a tapered inner surface such that the diameter on the p-side electrode 31 side is smaller than the diameter (several tens of μm) on the n-side electrode 32 side.

Next, as shown in FIG. 12 (k), the plasma CVD method is used to extend about 200 nm from the inner side surface of the through hole 120a and the inner side surface of the through hole 120b so as to extend onto a partial region of the n-side electrode 32, respectively. An insulating film 35 made of a SiO ₂ film having a thickness of 1 mm is formed.

  Next, as shown in FIG. 12 (l), the insulating film except for the region where the external connection electrode 36a and the external connection electrode 36b (see FIGS. 1A and 1B) are to be formed in a later step. A resist 40 is formed on 35 and the n-side electrode 32. Thereafter, external connection electrodes 36a and 36b having a thickness of about 0.3 μm are formed on the entire surface of the insulating film 35 and the resist 40 by using an electron beam evaporation method. At this time, a Ti layer, a Pt layer, and an Au layer are sequentially formed. Thereafter, the resist 40 is removed by a lift-off method.

  As a result, as shown in FIG. 12 (m), the external connection electrode 36a and the external connection electrode 36b are separated. Thereby, the red laser element 120 of the first embodiment is formed.

(F-3) Joining Method of Blue-violet Laser Element 110 and Red Laser Element 120 Next, a joining method of the blue-violet laser element 110 and the red laser element 120 will be described with reference to FIG.

  As shown in FIG. 13, the alignment is performed by fitting into the alignment recess 38 of the red laser element 120 with the alignment projection 18 of the blue-violet laser element 110 facing downward. At this time, from the transparent region 111 of the blue-violet laser element 110 shown in FIGS. 8A and 8B, the alignment convex portion 18 and the alignment concave portion 38 are visually observed as shown in FIG. Fit in the Z direction.

  Then, it is made of Au—Sn formed on the blue-violet laser element 110 by performing heat treatment under a temperature condition of about 280 ° C. in a state where the alignment convex portion 18 is fitted in the alignment concave portion 38. The solder layers 115a and 115b are melted. Thereafter, the solder layers 115a and 115b are solidified in the cooling process to room temperature, so that the blue-violet laser element 110 and the red laser element 120 are bonded to each other by the solder layers 115a and 115b via the insulating films 12 and 33.

  Thereafter, the light emitting surface 102 (see FIG. 1B) is formed by simultaneously cleaving the blue-violet laser element 110 and the red laser element 120 bonded to each other, and then separated into individual integrated semiconductor laser elements. To do. Finally, as shown in FIGS. 1A and 1B, the wires 122a, 122b, and the wires 122a, 122b are formed on the surfaces of the n-side electrode 32, the external connection electrode 36a, and the external connection electrode 36b of the red laser element 120. By bonding 122c, an integrated semiconductor laser element is formed.

(2) Second Embodiment (a) Overall Schematic Structure of Integrated Semiconductor Laser Element FIG. 14 (a) is a schematic cross section showing the structure of an integrated semiconductor laser element according to the second embodiment of the present invention. FIG. 14B is a plan view showing the upper surface of FIG. FIG. 14A is a sectional view taken along line 200-200 in FIG. The structure of the integrated semiconductor laser device according to the second embodiment will be described with reference to FIGS. 14 (a) and 14 (b).

  As shown in FIG. 14A, the integrated semiconductor laser device according to the second embodiment has a structure in which a monolithic laser device 300 and a blue-violet laser device 110 are stacked (integrated). The monolithic laser element 300 has a structure in which a red laser element 120 and an infrared laser element 130 are integrally formed on the same substrate.

  The blue-violet laser element 110 in FIG. 14 has the same structure as the blue-violet laser element 110 shown in FIG.

  The red laser element 120 shown in FIG. 14 is formed on an n-type GaAs substrate 51 that is shared with a semiconductor laser element (hereinafter referred to as an infrared laser element) 130 that emits infrared laser light described below. Except for this, it has the same structure as the red laser element 120 shown in FIG.

(B) Structure of Infrared Laser Element 130 Next, the structure of the infrared laser element 130 in FIG. 14 will be described. FIG. 15 is a detailed sectional view of the infrared laser device 130 of FIG.

  As shown in FIG. 14, an n-type buffer layer 52 made of n-type GaAs having a thickness of about 300 nm is formed in a predetermined region excluding the region where the red laser element 120 (FIG. 14) is formed on the n-type GaAs substrate 51. Is formed. An n-type cladding layer 53 made of n-type AlGaAs having a thickness of about 2 μm is formed on the n-type buffer layer 52. An active layer 54 having a thickness of about 70 nm is formed on the n-type cladding layer 53. The active layer 54 has an MQW structure in which a plurality of well layers made of undoped AlGaAs and a plurality of barrier layers made of undoped AlGaAs are alternately stacked.

  A p-type first cladding layer 55 made of p-type AlGaAs having a thickness of about 300 nm is formed on the active layer 54. A convex p-type second clad layer 56 made of p-type AlGaAs having a thickness of about 1.2 μm is formed in a predetermined region on the p-type first clad layer 55. A p-type cap layer 57 made of p-type GaAs having a thickness of about 100 nm is formed on the p-type second cladding layer 56. A p-type contact layer 58 made of p-type GaAs having a thickness of about 300 nm is formed on the p-type cap layer 57.

  The p-type contact layer 58, the p-type cap layer 57, and the p-type second cladding layer 56 constitute a ridge portion 59 having a taper-shaped side surface that decreases in width from the lower end toward the upper end. Yes. An angle θ4 formed by the side surface of the ridge portion 59 and the surface of the active layer 24 (p-type first cladding layer 25) is about 60 °. The width of the upper end of the ridge portion 59 is about 2.7 μm.

  The ridge portion 29 is formed in a stripe shape (elongated shape) extending in a direction (Y direction) perpendicular to the light emitting surface (cleavage surface) 202 shown in FIG. As shown in FIG. 15, the portion of the active layer 54 below the ridge portion 59 becomes the light emission point 64 of the infrared laser element 130.

  Here, in the second embodiment, a thickness (about 2 μm) larger than the height (about 1.6 μm) of the ridge portion 59 so as to cover the side surface of the ridge portion 59 on the p-type first cladding layer 55. .. 0 μm) is formed. The n-type current blocking layer 60 has an opening 60a through which the surface of the ridge portion 59 is exposed. The opening 60a of the n-type current blocking layer 60 has a tapered shape such that the width of the upper end (about 3 μm) is larger than the width of the bottom (the width of the upper end of the ridge portion 59 (about 2.7 μm)). It has a side.

  The angle θ5 formed by the inner surface of the opening 60a of the n-type current blocking layer 60 and the surface of the active layer 54 is about 70 °. Further, the opening 60 a of the n-type current blocking layer 60 is formed in a stripe shape (elongated shape) extending in the Y direction along the ridge portion 59 as shown in FIG. The n-type current blocking layer 60 is composed of an n-type GaAs layer.

  A p-side electrode 61 having a thickness of about 0.3 μm is formed in a region including the opening 60a on the n-type current blocking layer 60 (p-type contact layer 58). The p-side electrode 61 is composed of an AuZn layer, a Pt layer, and an Au layer in this order from the n-type GaAs substrate 51 side. A positioning recess 68 is formed in the p-side electrode 61 that covers the opening 60 a of the n-type current blocking layer 60. As a result, the depth of the alignment recess 68 (corresponding to the depth from the upper surface of the n-type current blocking layer 60 to the upper surface of the p-type contact layer 58) D2 is about 400 nm. That is, the depth D2 (about 400 nm) of the alignment concave portion 68 of the infrared laser element 130 is larger than the height H1 (153 nm) of the alignment convex portion 18. In the present embodiment, the alignment recess 68 is used for alignment of the monolithic laser element 300 on the blue-violet laser element 110.

  An n-side electrode 62 having a thickness of about 1 μm is formed on the back surface of the n-type GaAs substrate 51. Hereinafter, the n-type buffer layer 52, the n-type cladding layer 53, the active layer 54, the p-type first cladding layer 55, the p-type second cladding layer 56, the p-type intermediate layer 57, and the p-type contact layer 58 are combined into the element constituent layer c. Call it.

(C) Overall Detailed Structure of Integrated Semiconductor Laser Element Here, the overall structure of the integrated semiconductor laser element according to the present embodiment will be described with reference to FIG.

  After forming insulating layers 72 and solder layers 73a, 73b, 73c made of Au-Sn on blue-violet laser element 110, and forming insulating layers 63 and solder layers 73d made of Au-Sn on infrared laser element 130 The blue-violet laser element 110 and the monolithic laser element 300 are joined so that the alignment convex portion 18 of the blue-violet laser element 110 fits into the alignment concave portion 68 of the infrared laser element 130 of FIG. Is done.

  The n-side electrode 11 of the blue-violet laser element 110 is bonded on the conductive submount 1000. Also, the solder layers 73a, 73b, 73c are electrically separated from each other by the insulating films 63, 72. The solder layer 73d is integrated with the solder layer 73a.

  The emission point 13 of the blue-violet laser element 110 and the emission point 64 of the infrared laser element 130 are disposed on the same line in the stacking direction (Z direction) of the semiconductor layers. Further, as described above, the depth D2 (about 400 nm) of the alignment recess 68 of the monolithic laser element 300 is greater than the height H1 (153 nm) of the alignment protrusion 18 of the blue-violet laser element 110. Therefore, the distance between the upper surface of the convex portion 18 for alignment of the blue-violet laser element 110 and the bottom surface of the concave portion 68 for alignment of the monolithic laser element 300 is the same as that for alignment of the blue-violet laser element 110. The distance between the region other than the convex portion 18 and the region other than the concave portion 38 for alignment of the monolithic laser element 300 is larger.

  In addition, a circular through hole 220a that penetrates the n-type GaAs substrate 51, the element configuration layer b, the n-type current block layer 60, and the p-side electrode 31, and the n-type GaAs substrate 51, the element configuration layer c, the n-type current block Through holes 220b and 220c penetrating the layer 60 and the p-side electrode 61 are formed. The through holes 220a, 220b, and 220c have a taper shape such that the diameter on the n-side electrode 62 side is several tens of μm, and the diameter on the p-side electrodes 31 and 61 side is smaller than the diameter on the n-side electrode 62 side. It has an inner surface.

An insulating film 65 made of a SiO ₂ film having a thickness of about 200 nm is formed so as to extend from the inner side surface of each of the through holes 220a, 220b, and 220c onto a partial region of the n-side electrode 62.

  An external connection electrode 66a having a thickness of about 0.3 μm is formed on the inner surface of the through hole 220a and the region on the insulating film 65 on the n-side electrode 62 so as to be electrically connected to the solder layer 73a. Has been. In addition, an external connection electrode 66b similar to the external connection electrode 66a is electrically connected to the solder layer 73b on the inner surface of the through 220b and the region on the insulating film 65 on the n-side electrode 62. Is formed. The external connection electrodes similar to the external connection electrodes 66a and 66b are electrically connected to the inner surface of the through-hole 220c and the region on the insulating film 65 on the n-side electrode 62 so as to be electrically connected to the solder layer 73c. The external connection electrodes 66a, 66b, 66c formed with 66c are composed of a Ti layer, a Pt layer, and an Au layer in this order from the n-type GaAs substrate 51 side.

  One end of a wire 222a made of a gold wire or the like is bonded to the n-side electrode 62, and the other end of the wire 222a is bonded to the conductive submount 1000. A wire 222b is bonded to the external connection electrode 66a, a wire 222c is bonded to the external connection electrode 66b, and a wire 222d is bonded to the external connection electrode 66c.

  In this case, the p-side electrode 31 of the red laser element 120 is electrically connected to the external connection electrode 66a through the solder layer 73a. The p-side electrode 61 of the infrared laser element 130 is electrically connected to the external connection electrode 66b through the solder layer 73b. The p-side electrode 10 of the blue-violet laser element 110 is electrically connected to the external connection electrode 66c through the solder layer 73c.

(D) Effects of the second embodiment In the second embodiment, as described above, the alignment convex portion 18 is fitted into the alignment concave portion 68 to thereby adjust the alignment. The horizontal direction of the blue-violet laser element 110 and the monolithic laser element 300 when the blue-violet laser element 110 and the monolithic laser element 300 are stacked by fitting the convex portion 18 and the concave portion 68 (FIG. 14 (a) X Misalignment in the direction) can be prevented. This prevents the optical axis of the emitted light from the blue-violet laser element 110 and the optical axis of the emitted light from the infrared laser element 130 from shifting in the horizontal direction (X direction in FIG. 14A). Therefore, it is easy to adjust the optical axis of the emitted light with respect to the optical system when used by making the emitted light of the integrated semiconductor laser element incident on the optical system (lens, mirror, etc.). Therefore, the cost for adjusting the optical axis can be reduced.

  Further, it is possible to prevent displacement of the blue-violet laser element 110 and the monolithic laser element 300 in the horizontal direction (X direction in FIG. 14A) when the blue-violet laser element 110 and the monolithic laser element 300 are stacked. Therefore, it is possible to prevent the cleavage directions of the blue-violet laser element 110 and the monolithic laser element 300 from being shifted from each other. As a result, after the blue-violet laser element 110 and the monolithic laser element 300 are bonded together, the blue-violet laser element 110 and the infrared laser element 130 are simultaneously cleaved in order to form a light emitting surface that is a cavity end face. Cleavage can be improved. As a result, the characteristics of the laser beam emitted from the light emitting surface (cleavage surface) 202 can be improved.

  Further, the p-side electrode 10 of the blue-violet laser element 110, the p-side electrode 31 of the red laser element 120, and the p-side electrode 61 of the infrared laser element 130 are electrically separated through the insulating film 72 and the insulating film 63. Yes. Thereby, the n-side electrode 11 of the blue-violet laser element 110 and the n-side electrode 62 of the monolithic laser element 300 can be used as a common electrode. In this case, an arbitrary voltage can be applied to the p-side electrode 10 of the blue-violet laser element 110, the p-side electrode 31 of the red laser element 120, and the p-side electrode 61 of the infrared laser element 130, respectively.

  Further, the external connection electrode 66a, the external connection electrode 66b, and the external connection electrode 66c are connected by wires, and wires are bonded to the n-side electrode 62 and the conductive submount 1000 of the monolithic laser element 300, respectively. The p-side electrode 10 of the blue-violet laser element 110, the p-side electrode 31 of the red laser element 120, and the p-side electrode 61 of the infrared laser element 130 can be used as a common electrode. In this case, an arbitrary voltage can be applied to the n-side electrode 11 of the blue-violet laser element 110 and an arbitrary voltage can be applied to the n-side electrode 62 of the monolithic laser element 300.

  In the second embodiment, the emission point 13 of the blue-violet laser element 110 and the emission point 64 of the infrared laser element 130 are on the same line in the stacking direction of the semiconductor layers (Z direction in FIG. 14A). Are arranged in two directions (semiconductor layer stacking direction (Z direction in FIG. 14A)) and horizontal direction (see FIG. 14). 14 (a) in the X direction)), the distance between the emission point 13 of the blue-violet laser element 110 and the emission point 64 of the infrared laser element 130 can be reduced. Thus, when the light emitted from the integrated semiconductor laser element is incident on an optical system (such as a lens and a mirror) and used, one of the emission point 13 of the blue-violet laser element 110 and the emission point 64 of the infrared laser element 130 is used. When the optical axis is adjusted so that the light emitted from the light enters the predetermined region of the optical system, the light emitted from the other of the light emitting point 13 of the blue-violet laser element 110 and the light emitting point 64 of the infrared laser element 130 Can be prevented from entering a region greatly deviating from a predetermined region of the optical system. As a result, the optical axis adjustment with respect to the optical system becomes easier, so that the cost for the optical axis adjustment can be further reduced.

  In the second embodiment, the convex portion 18 (ridge portion 8) for alignment of the blue-violet laser element 110 extends in a direction perpendicular to the light emitting surface 202 (Y direction in FIG. 14B). In this manner, the alignment recess 68 (opening 60a of the n-type current blocking layer 60) of the monolithic laser element 300 is formed in a direction perpendicular to the light emitting surface 202 (FIG. 14). A direction in which the region where the alignment convex portion 18 and the concave portion 68 are fitted is orthogonal to the light emitting surface 202 by forming in a stripe shape (elongated shape) rather than extending in the Y direction (b). (Y direction in FIG. 14B) becomes longer. This prevents the horizontal displacement (X direction in FIG. 14B) of the blue-violet laser element 110 and the monolithic laser element 300 when the blue-violet laser element 110 and the monolithic laser element 300 are stacked. be able to.

  In the second embodiment, the convex portion 18 for alignment of the blue-violet laser element 110 is formed so as to have a tapered shape in which the width at the upper end is smaller than the width at the lower end, and the monolithic type By forming the concave portion 68 of the laser element 300 so as to have a tapered shape such that the width of the lower end is smaller than the width of the upper end, the alignment convex portion 18 can be easily fitted into the alignment concave portion 68. Can be included.

  In the second embodiment, the alignment convex portion 18 of the blue-violet laser element 110 and the alignment concave portion 68 of the monolithic laser element 300 are connected to the solder layer 73a, the solder layer 73b, and the solder layer 73c. By joining them, the convex portion 18 for alignment of the blue-violet laser element 110 and the concave portion 68 for alignment of the monolithic laser element 300 are easily formed by the solder layer 73a, the solder layer 73b, and the solder layer 73c. Can be joined.

  Further, in the second embodiment, the distance between the upper surface of the alignment convex portion 18 of the blue-violet laser element 110 and the bottom surface of the alignment concave portion 68 of the monolithic laser element 300 is set as the blue-violet laser element. 110. The alignment convex portion of the blue-violet laser element 110 is made larger than the distance between the region other than the alignment convex portion 18 of 110 and the region other than the alignment concave portion 68 of the monolithic laser element 300. Even if a region other than 18 and a region other than the alignment recess 68 of the monolithic laser element 300 come into contact, the upper surface of the alignment projection 18 and the bottom surface of the alignment recess 68 contact each other. Can be prevented. This prevents stress from being applied to the ridge portions 8 and 59 when the alignment convex portion 18 of the blue-violet laser element 110 and the alignment concave portion 68 of the monolithic laser element 300 are joined. Can do.

  In the second embodiment, since the n-type current blocking layer 60 of the monolithic laser element 300 is made of n-type GaAs having good heat dissipation characteristics, the heat dissipation characteristics of the integrated semiconductor laser element can be improved. it can.

(E) Manufacturing Method of Integrated Semiconductor Laser Device Next, a manufacturing method of the integrated semiconductor laser device according to the second embodiment will be described.

  16 to 22 are process cross-sectional views for explaining a method of manufacturing the integrated semiconductor laser device of FIG. Next, with reference to FIGS. 14-22, the manufacturing method of the integrated semiconductor laser element by 2nd Embodiment is demonstrated.

  In the second embodiment, the blue-violet laser element 110 is formed by the steps shown in FIGS. 16A to 16C, and the monolithic type is obtained by the process shown in FIGS. 17A to 23O. A laser element 300 is formed.

(E-1) Method of forming blue-violet laser device 110 When forming the blue-violet laser device 110, the p-side shown in FIG. 16 (a) is formed by the same steps as in FIGS. 4 (a) to 6 (h). The electrode 10 is formed.

Next, as shown in FIG. 16B, the back surface of the n-type GaN substrate 1 is polished until the thickness from the upper surface of the ridge portion 8 to the back surface of the n-type GaN substrate 1 becomes about 150 μm. Further, an insulating film 72 made of a SiO ₂ film having a thickness of about 200 nm is formed on the p-side electrode 10 by using a plasma CVD method so that a partial region of the p-side electrode 10 except on the ridge 8 is exposed. To do.

  Next, as shown in FIG. 16C, an n-side electrode 11 is formed on the back surface of the n-type GaN substrate 1 by using an electron beam evaporation method. At this time, an Al layer having a thickness of about 6 nm, a Pd layer having a thickness of about 10 nm, and an Au layer having a thickness of about 300 nm are sequentially formed. In this way, the blue-violet laser element 110 is formed.

  In this case, as shown in FIG. 8B, the end portion of the n-side electrode 11 positioned on the side of the end face 1a parallel to the light emitting surface 202 of the n-type GaN substrate 1 (see FIG. 14B) is formed. The n-type GaN substrate 1 is disposed in a region spaced a predetermined distance from the end face 1a. As a result, as shown in FIGS. 8A and 8B, the region where the p-side electrode 10 and the n-side electrode 11 are not formed has the blue-violet laser element 110 and the monolithic laser element 300. At the time of lamination, the ridge portion 8 of the blue-violet laser element 110 becomes a transparent region 111 that can be visually recognized from above or below.

  Thereafter, a solder layer 73a and a solder layer 73b are formed in predetermined regions on the insulating film 72, respectively. The solder layer 73a is formed in a region not including the ridge portion, and the solder layer 73b is formed in a region including the ridge portion. Further, a solder layer 73c is formed on the exposed p-side electrode 10.

(E-2) Method for Forming Monolithic Laser Element 300 Next, when forming the monolithic laser element 300, first, as shown in FIG. c is formed. Specifically, an n-type buffer layer 52 made of n-type GaAs having a thickness of about 300 nm is grown on the n-type GaAs substrate 51 by using the MOCVD method. An n-type cladding layer 53 made of n-type AlGaAs having a thickness of 2 μm is grown. Thereafter, an active layer 54 having a thickness of about 70 nm is grown on the n-type cladding layer 53. When the active layer 54 is grown, a plurality of well layers made of undoped AlGaAs and a plurality of barrier layers made of undoped AlGaAs are grown alternately. As a result, an active layer 54 having an MQW structure in which a plurality of well layers and a plurality of barrier layers are alternately stacked is formed on the n-type cladding layer 53.

  Next, a p-type first cladding layer 55 made of p-type AlGaAs having a thickness of about 300 nm and a p-type second cladding layer 56 made of p-type AlGaAs having a thickness of about 1.2 μm are sequentially formed on the active layer 54. Grow.

  Subsequently, after a p-type cap layer 57 made of p-type GaAs having a thickness of about 100 nm is grown on the p-type second cladding layer 56, a p-type having a thickness of about 300 nm is formed on the p-type cap layer 57. A p-type contact layer 58 made of GaAs is grown. In this way, the element constituent layer c is formed.

  Next, as shown in FIG. 17B, a resist 74 is formed in a predetermined region on the element constituent layer c.

  Next, as shown in FIG. 17C, the element constituent layer c is etched by using a wet etching technique with phosphoric acid and hydrogen peroxide solution, using the resist 74 as a mask. Thereafter, the resist 74 is removed.

  Next, as shown in FIG. 18D, the p-type contact layer 28 of the red laser element 120 in FIG. 3 is formed on the n-type GaAs substrate 51 and the element constituent layer c by the same process as in FIG. The element constituent layer b to be removed is formed. The p-type contact layer 28 in FIG. 3 is formed in a later process. Next, a resist 75 is formed in a predetermined region of the element constituent layer b formed on the n-type GaAs substrate 51.

  Next, as shown in FIG. 18E, the element constituent layer b is etched using the resist 75 as a mask by using a wet etching technique using a mixed solution of hydrobromic acid, hydrochloric acid and water. Thereafter, the resist 75 is removed. In this manner, the element constituent layer b excluding the p-type contact layer 28 of the red laser element 120 and the element constituent layer c of the infrared laser element 130 are formed on the n-type GaAs substrate 51 with an interval therebetween. The

Next, as shown in FIG. 19F, regions where the ridge 29 (see FIG. 3) and the ridge 59 (see FIG. 15) are to be formed on the element constituent layers b and c using the plasma CVD method. Then, an SiO ₂ film 76 and an SiO ₂ film 77 having a thickness of about 240 nm are formed.

Next, as shown in FIG. 19G, the p-type contact layer 28 of the red laser element 120 is formed using the SiO ₂ film 76 as a mask by using a wet etching technique using a mixed solution of hydrobromic acid, hydrochloric acid and water. Then, the p-type intermediate layer 27 and the p-type second cladding layer 26 are etched (see FIG. 3). Also, using the wet etching technique with phosphoric acid and hydrogen peroxide, using the SiO ₂ film 77 as a mask, the p-type contact layer 58, the p-type cap layer 57, and the p-type second cladding layer 56 of the infrared laser element 130 are used. Is etched (see FIG. 15). Thereby, a ridge portion 29 having a tapered side surface is formed in the element constituent layer b, and a ridge portion 59 having a tapered side surface is formed in the element constituent layer c. As shown in FIG. 14B, the ridge portion 29 and the ridge portion 59 are formed in a stripe shape (elongated shape) extending in a direction orthogonal to the light emitting surface 202.

Next, as shown in FIG. 19H, a thickness of about 2 μm is formed on the entire surface of the element constituent layer b and the element constituent layer c using the SiO ₂ films 76 and 77 as a selective growth mask using the MOCVD method. The n-type current blocking layer 60 is formed. In this case, the n-type current blocking layer 60 is selectively grown on the upper surface of the element constituent layer b and the element constituent layer c, and then grown laterally so as to cover the SiO ₂ films 76 and 77.

Next, as shown in FIG. 20 (i), using a plasma CVD method, a region other than the striped (elongated) region on the n-type current blocking layer 60 above the SiO ₂ films 76 and 77 is formed. An SiO ₂ film 78 having a thickness of about 240 nm is formed. Next, the n-type current blocking layer 60 located above the upper surfaces of the ridge portion 29 and the ridge portion 59 is etched using the SiO ₂ film 78 as a mask by using a wet etching technique using a phosphoric acid-based etchant. Thereby, openings 30a and 60a are formed on the ridge portion 29 and the ridge portion 59, respectively. At this time, the opening 30a and the opening 60a of the n-type current blocking layer 60 are formed to have a tapered inner surface such that the width of the lower end is smaller than the width of the upper end.

The angle θ5 formed by the inner surface of the opening 60a of the n-type current blocking layer 60 and the upper surface of the active layer 54 (p-type contact layer 58) is 70 °. The width of the upper end of the opening 60a of the n-type current blocking layer 60 is about 3 μm, and the width of the lower end is about 2.7 μm. Further, the opening 30 a and the opening 60 a of the n-type current blocking layer 60 are formed in a stripe shape (elongated shape) along the ridge portion 29 and the ridge portion 59. Thereafter, the SiO ₂ films 76, 77 and 78 are removed. Thereafter, a p-type contact layer 28 is formed on the p-type intermediate layer 27 (see FIG. 3) in the opening 30a by MOCVD.

  Next, as shown in FIG. 20 (j), an electron beam evaporation method is used so as to extend from the bottom and inner surfaces of the openings 30a and 60a to a partial region on the n-type current blocking layer 60. P-side electrodes 31 and 61 having a thickness of about 0.3 μm are formed. At this time, an AuZn layer and a Pt layer are sequentially formed.

  Further, the back surface of the n-type GaAs substrate 51 is polished until the thickness from the upper surface of the ridge portion 59 to the back surface of the n-type GaAs substrate 51 becomes about 100 μm. Next, a resist 79 is formed on the n-type current blocking layer 60 and the p-side electrodes 31 and 61 except for the region above the element constituent layer b and the element constituent layer c. Thereafter, the n-type current blocking layer 60 is etched using the resist 79 as a mask by using a wet etching technique. Thereby, the red laser element 120 and the infrared laser element 130 are separated. Thereafter, the resist 79 is removed.

  As a result, the depth D2 of the alignment recess 68 is about 400 nm. That is, the depth D2 (about 400 nm) of the alignment concave portion 68 used for alignment of the monolithic laser element 300 is the height H1 (153 nm) of the alignment convex portion 18 (see FIG. 1A). Bigger than.

Next, as shown in FIG. 21 (k), an insulating layer made of SiO _{2 is} formed on a region separated from the p-side electrode 61 on the n-type current blocking layer 60 of the infrared laser element 130 by using plasma CVD. A film 63 is formed.

  Next, as shown in FIG. 21 (l), through holes 220a, 220b, and 220c (see FIG. 14 (a)) are formed in the rear surface of the n-type GaAs substrate 51 in a later step by using an electron beam evaporation method. The n-side electrode 62 having a thickness of about 1 μm is formed except for the region to be formed. At this time, an AuGe layer, a Ni layer, and an Au layer are sequentially formed.

  Next, using the RIE method using a chlorine-based gas, the n-side electrode 62 is used as a mask, and a circle penetrating the element constituting layer b, the n-type current blocking layer 60 and the p-side electrode 31 from the back surface of the n-type GaAs substrate 51. A shaped through-hole 220a is formed. Similarly, a circular through hole 220b penetrating the element constituent layer c, the n-type current blocking layer 60 and the p-side electrode 61 is formed from the back surface of the n-type GaAs substrate 51, and from the back surface of the n-type GaAs substrate 51. Then, a circular through hole 220c penetrating the element constituent layer c, the n-type current blocking layer 60 and the insulating film 63 is formed. The through holes 220a, 220b, and 220c are tapered so that the diameters on the p-side electrode 31, the p-side electrode 61, and the insulating film 80 side are smaller than the diameter (several tens of μm) on the n-type GaAs substrate 51 side. It is formed to have side surfaces.

Next, as shown in FIG. 22 (m), partial regions of the n-side electrode 62 are respectively formed from the inner side surface of the through hole 220a, the inner side surface of the through hole 220b, and the inner side surface of the through hole 220c by plasma CVD. An insulating film 65 made of a SiO ₂ film having a thickness of about 200 nm is formed so as to extend upward.

  Next, as shown in FIG. 22 (n), the external connection electrode 66a, the external connection electrode 66b and the external connection shown in FIG. 14 (a) and FIG. A resist 80 is formed except for a region where the connection electrode 66c is to be formed. Thereafter, external connection electrodes 66a, 66b, 66c having a thickness of about 0.3 μm are formed on the entire surface of the insulating film 65 and the resist 80 by using an electron beam evaporation method. At this time, a Ti layer, a Pt layer, and an Au layer are sequentially formed. Thereafter, the resist 80 is removed by a lift-off method.

  Thereby, as shown in FIG. 23 (o), the external connection electrode 66a, the external connection electrode 66b, and the external connection electrode 66c are separated. Thereby, the monolithic laser element 300 of the second embodiment is formed. Next, a solder layer 73 d is formed on the p-side electrode 31 that extends from the bottom surface and inner side surface of the recess 38 to a partial region around the recess 38.

(E-3) Joining Method of Blue Purple Laser Element 110 and Monolithic Laser Element 300 Next, a joining method of the blue purple laser element 110 and the monolithic laser element 300 will be described with reference to FIG.

  As shown in FIG. 24, the alignment is performed by fitting into the alignment recess 68 of the monolithic laser element 300 with the alignment protrusion 18 of the blue-violet laser element 110 facing downward. . At this time, from the transparent region 111 of the blue-violet laser element 110 shown in FIGS. 8A and 8B, the alignment convex portion 18 and the alignment concave portion 68 are visually observed as shown in FIG. Fit in the Z direction. Then, it is made of Au—Sn formed on the blue-violet laser element 110 by heat treatment under a temperature condition of about 280 ° C. in a state where the alignment convex portion 18 is fitted in the alignment concave portion 68. The solder layers 73a, 73b, 73c, 73d are melted. Thereafter, the solder layers 73a, 73b, 73c, 73d are solidified in the cooling process to room temperature, so that the blue-violet laser element 110 and the monolithic laser element 300 are solder layers 73a, 73b via the insulating films 63, 72. , 73c, 73d.

  Thereafter, the blue-violet laser element 110 and the monolithic laser element 300 bonded to each other are simultaneously cleaved to form the light emitting surface 202 (see FIG. 14B), and then the individual integrated semiconductor laser elements are formed. To separate. Finally, as shown in FIGS. 14A and 14B, the wires 222a, 222b, 222c, and 222c are formed on the surfaces of the n-side electrode 62 and the external connection electrodes 66a, 66b, and 66c of the red laser element 120. 222d is bonded.

(3) Correspondence between each component of claims and each part of the embodiment In the first embodiment, the blue-violet laser element 110 corresponds to the first semiconductor laser element, and the red laser element 120 corresponds to the second laser element. Corresponding to a semiconductor laser element, the n-type GaN substrate 1 corresponds to the first substrate, the n-type GaAs substrate 21 corresponds to the second substrate, and the blue-violet laser light corresponds to the laser light of the first wavelength. The red laser beam corresponds to the second wavelength laser beam, the light emission point 13 corresponds to the first light emission point, and the light emission point 34 corresponds to the second light emission point.

  The element constituent layer a, the p-type contact layer 7 and the current blocking layer 9 correspond to the first semiconductor layer, the element constituent layer b and the n-type current blocking layer 30 correspond to the second semiconductor layer, and the n-side electrode 11. Corresponds to the first electrode, the p-side electrode 10 corresponds to the second electrode, the n-side electrode 32 corresponds to the third electrode, and the p-side electrode 31 corresponds to the fourth electrode.

  The alignment convex portion 18 corresponds to a convex portion, the alignment concave portion 38 corresponds to a concave portion, the through hole 120b corresponds to a first through hole, and the through hole 120a corresponds to a second through hole. The external connection electrode 36b corresponds to the first extraction electrode, and the external connection electrode 36a corresponds to the second extraction electrode.

  The n-type cladding layer 2 corresponds to the first cladding layer, the p-type cladding layer 6 corresponds to the second cladding layer, the n-type cladding layer 23 corresponds to the third cladding layer, and the p-type first cladding. The layer 25 and the p-type second cladding layer 26 correspond to the fourth cladding layer, the active layer 3 corresponds to the first active layer, and the active layer 24 corresponds to the second active layer.

  In the second embodiment, the infrared laser element 130 corresponds to the second semiconductor laser element, the red laser element 120 corresponds to the third semiconductor laser element, and the n-type GaAs substrate 51 corresponds to the second and third semiconductor laser elements. The infrared laser beam corresponds to the second wavelength laser beam, the red laser beam corresponds to the third wavelength laser beam, and the light emitting point 64 corresponds to the second light emitting point. The light emission point 34 corresponds to the third light emission point.

  The element configuration layer c and the n-type current block layer 60 correspond to the second semiconductor layer, the element configuration layer b and the n-type current block layer 60 correspond to the third semiconductor layer, and the n-side electrode 62 includes the third and third layers. It corresponds to the fifth electrode, the p-side electrode 61 corresponds to the fourth electrode, and the p-side electrode 31 corresponds to the sixth electrode.

  The through hole 220c corresponds to the first through hole, the through hole 220b corresponds to the second through hole, the through hole 220a corresponds to the third through hole, and the external connection electrode 66c is the first extraction electrode. The external connection electrode 66b corresponds to the second extraction electrode, and the external connection electrode 66a corresponds to the third extraction electrode. Correspondence of the other parts of the second embodiment is the same as that of the first embodiment.

(4) Other Modifications The material of the insulating film is not limited to SiO ₂ , and other insulating materials such as SiNx, TiO ₂ , ZrO ₂ may be used.

  In the first and second embodiments, the blue-violet laser element 110 is provided with an alignment projection 18, and the red laser element 120 and the monolithic laser element 300 are provided with an alignment recess 38 and an alignment recess. 68, the blue-violet laser element 110 may be provided with a concave portion for alignment, and the red laser element 120 and the monolithic laser element 300 may be provided with a convex portion for alignment.

  INDUSTRIAL APPLICABILITY The present invention can be effectively used for an optical pickup device, a display device, a light source, etc. for recording and reproducing a plurality of types of optical recording media and for manufacturing them.

1 is a schematic cross-sectional view and a plan view showing a structure of an integrated semiconductor laser device according to a first embodiment. FIG. 2 is a detailed sectional view showing the blue-violet laser element of FIG. 1. FIG. 2 is a detailed cross-sectional view showing the red laser element of FIG. 1. It is process sectional drawing which shows the manufacturing process of the blue-violet laser element of FIG. It is process sectional drawing which shows the manufacturing process of the blue-violet laser element of FIG. It is process sectional drawing which shows the manufacturing process of the blue-violet laser element of FIG. It is process sectional drawing which shows the manufacturing process of the blue-violet laser element of FIG. It is a top view which shows the blue-violet laser element of FIG. It is process sectional drawing which shows the manufacturing process of the red laser element of FIG. It is process sectional drawing which shows the manufacturing process of the red laser element of FIG. It is process sectional drawing which shows the manufacturing process of the red laser element of FIG. It is process sectional drawing which shows the manufacturing process of the red laser element of FIG. It is process sectional drawing which shows the joining method of a blue-violet laser element and a red laser element. It is the schematic sectional drawing and top view which show the integrated semiconductor laser apparatus which concerns on 2nd Embodiment. FIG. 15 is a detailed cross-sectional view showing the infrared laser device of FIG. 14. It is process sectional drawing which shows a manufacturing process of the blue-violet laser element of FIG. FIG. 15 is a process cross-sectional view illustrating a manufacturing process of the monolithic laser element in FIG. 14. FIG. 15 is a process cross-sectional view illustrating a manufacturing process of the monolithic laser element in FIG. 14. FIG. 15 is a process cross-sectional view illustrating a manufacturing process of the monolithic laser element in FIG. 14. FIG. 15 is a process cross-sectional view illustrating a manufacturing process of the monolithic laser element in FIG. 14. FIG. 15 is a process cross-sectional view illustrating a manufacturing process of the monolithic laser element in FIG. 14. FIG. 15 is a process cross-sectional view illustrating a manufacturing process of the monolithic laser element in FIG. 14. FIG. 15 is a process cross-sectional view illustrating a manufacturing process of the monolithic laser element in FIG. 14. It is process sectional drawing which shows the joining method of the blue-violet laser element of FIG. 14, and a monolithic type laser element. It is a perspective view which shows the structure of the conventional integrated semiconductor laser element.

Explanation of symbols

1 n-type GaN substrate 8, 29, 59 Ridge portion 10, 31, 61 p-side electrode 11, 32, 62 n-side electrode 12, 33, 35, 63, 65, 72 Insulating film 13, 34, 64 Light emitting point 18 convex Portions 21, 51 n-type GaAs substrates 30a, 60a Openings 36a, 36b, 66a, 66b, 66c External connection electrodes 38, 68 Recesses 73a, 73b, 73c, 115a, 115b Solder layers 120a, 120b, 220a, 220b, 220c Through hole

Claims (12)

A first semiconductor laser element;
A second semiconductor laser element laminated on the first semiconductor laser element via an insulating film,
The first semiconductor laser element includes a first substrate and a first semiconductor layer that is formed on one surface of the first substrate and has a first light emitting point that emits laser light having a first wavelength. And a first electrode formed on the other surface of the first substrate, and a second electrode formed on the first semiconductor layer,
The second semiconductor laser element has a second substrate and a second semiconductor layer formed on one surface of the second substrate and having a second light emitting point that emits laser light having a second wavelength. And a third electrode formed on the other surface of the second substrate, and a fourth electrode formed on the second semiconductor layer,
The first semiconductor laser element has one of a convex portion and a concave portion on the first semiconductor layer side, and the second semiconductor laser element is the other of the concave portion and the convex portion on the second semiconductor layer side. Have
The insulating film is disposed between the second electrode of the first semiconductor laser element and the fourth electrode of the second semiconductor laser element, and the convex portion of the first semiconductor laser element An integrated semiconductor laser device, wherein one of the recess and the recess is fitted to the other of the recess and the projection of the second semiconductor laser device. The second semiconductor laser element has first and second through holes,
A first extraction electrode extending from the second electrode through the first through hole onto the other surface of the second substrate;
2. The integrated semiconductor laser device according to claim 1, further comprising a second extraction electrode extending from the fourth electrode to the other surface of the second substrate through the second through hole. . 2. The convex portion and the concave portion are provided so that the first light emitting point and the second light emitting point are located on a line in a direction perpendicular to one surface of the first substrate. Or the integrated semiconductor laser device according to 2; 4. The integrated semiconductor laser according to claim 1, wherein the convex portion and the concave portion are formed to extend in parallel with an emission direction of the laser light having the first or second wavelength. element. The first semiconductor layer includes a first cladding layer, a first active layer, and a second cladding layer in order, and the second cladding layer includes a flat portion and a ridge extending in a stripe shape on the flat portion. And
The second semiconductor layer includes a third cladding layer, a second active layer, and a fourth cladding layer in order, and the fourth cladding layer includes a flat portion and a ridge extending in a stripe shape on the flat portion. And
One of the convex portion and the concave portion is provided on the ridge portion of the second cladding layer, and the other of the concave portion and the convex portion is provided on the ridge portion of the fourth cladding layer. The integrated semiconductor laser device according to claim 1, wherein the integrated semiconductor laser device is a semiconductor laser device. The first semiconductor laser element has first and second regions;
The second semiconductor laser element is stacked on the first region of the first semiconductor laser element,
A third semiconductor laser element stacked on the second region of the first semiconductor laser element with the insulating film interposed therebetween;
The third semiconductor laser element includes a third substrate and a third semiconductor layer formed on one surface of the third substrate and having a third light emitting point that emits laser light having a third wavelength. The integrated circuit according to claim 1, further comprising: a fifth electrode formed on the other surface of the third substrate; and a sixth electrode formed on the third semiconductor layer. Type semiconductor laser device. The third semiconductor laser element has a third through hole,
7. The integrated semiconductor laser device according to claim 6, further comprising a third extraction electrode extending from the sixth electrode through the third through hole onto the other surface of the second substrate. 8. The integrated semiconductor laser device according to claim 6, wherein the second substrate and the third substrate are a common substrate. Forming a first semiconductor laser element;
Forming a second semiconductor laser element;
Laminating the second semiconductor laser element on the first semiconductor laser element via an insulating film,
The step of forming the first semiconductor laser element includes:
Forming a first semiconductor layer having a first light emitting point for emitting laser light having a first wavelength on one surface of the first substrate;
Forming one of a convex portion and a concave portion in the first semiconductor layer;
Forming first and second electrodes on the other surface of the first substrate and on the first semiconductor layer, respectively.
The step of forming the second semiconductor laser element includes:
Forming a second semiconductor layer having a second light emitting point for emitting a laser beam having a second wavelength on one surface of the second substrate;
Forming the other of the concave portion and the convex portion in the second semiconductor layer;
Forming third and fourth electrodes on the other surface of the second substrate and on the second semiconductor layer, respectively.
The step of laminating the second semiconductor laser element on the first semiconductor laser element via an insulating film includes:
The convex portion of the first semiconductor laser element such that the insulating film is disposed between the second electrode of the first semiconductor laser element and the fourth electrode of the second semiconductor laser element. And a step of fitting one of the concave portions with the other of the concave portion and the convex portion of the second semiconductor laser element. The first semiconductor laser element and the second semiconductor in a state where one of the convex portion and the concave portion of the first semiconductor laser element is fitted to the other of the concave portion and the convex portion of the second semiconductor laser element. 10. The method of manufacturing an integrated semiconductor laser device according to claim 9, further comprising a step of simultaneously cleaving the laser device. A step of forming a third semiconductor laser element;
The step of forming the second semiconductor layer includes:
Forming the second semiconductor layer in a first region of the one surface of the second substrate;
The step of forming the third semiconductor laser element includes:
Forming a third semiconductor layer having a third light emitting point for emitting laser light of a third wavelength in the second region of the one surface of the second substrate;
Forming a fifth electrode and a sixth electrode on a region of the second substrate on the opposite side of the third semiconductor layer and on the third semiconductor layer, respectively. A manufacturing method of the integrated semiconductor laser device described. The first semiconductor laser element and the second semiconductor in a state where one of the convex portion and the concave portion of the first semiconductor laser element is fitted to the other of the concave portion and the convex portion of the second semiconductor laser element. 12. The method of manufacturing an integrated semiconductor laser element according to claim 11, further comprising the step of cleaving the laser element and the third semiconductor laser element simultaneously.

Images