JP5245030B2 - Nitride-based semiconductor laser device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a nitride semiconductor laser element and a method for manufacturing the same, and more particularly to a nitride semiconductor laser element in which a nitride semiconductor element layer having a light emitting layer is formed on a substrate and a method for manufacturing the same.

  Conventionally, using a gallium arsenide-based semiconductor material, a monolithic type including a semiconductor element layer integrally formed with a resonator end face (light emitting face) and a reflecting face for reflecting laser emitted light to the outside A semiconductor laser element is disclosed (see, for example, Non-Patent Document 1).

  In the monolithic semiconductor laser device disclosed in Non-Patent Document 1, a resonator on the light emitting surface side is applied to a semiconductor device layer made of gallium arsenide uniformly stacked on a substrate by an ion beam etching technique. An end surface and a reflecting surface (inclined end surface) extending in a direction of 45 ° obliquely with respect to the resonator end surface are formed at a predetermined distance from the resonator end surface. Thereby, the laser emission light from the resonator end face is reflected in the direction substantially perpendicular to the substrate by the reflection surface and can be emitted to the outside.

Appl. Phys. Lett. 48 (24), 16 June 1986, p. 1675-1677

  However, the monolithic semiconductor laser element disclosed in Non-Patent Document 1 described above has a reflecting surface (tilted end surface) inclined by 45 ° with respect to the cavity end surface in order to emit laser light in a direction substantially perpendicular to the substrate. On the other hand, the surface orientation of the reflecting surface is not disclosed or suggested. Generally, when an end face is formed in a semiconductor element layer by using dry etching such as ion beam etching, a fine uneven shape is formed on the end face by etching. Therefore, in the monolithic type semiconductor laser element disclosed in Non-Patent Document 1, it is considered that the reflection surface has a fine uneven shape. In this case, since a part of the laser light emitted from the resonator end face (light emitting surface) is scattered by the reflecting surface, there is a problem that the light emission efficiency as the semiconductor laser element is lowered.

  The present invention has been made to solve the above-described problems, and one object of the present invention is a nitride-based semiconductor laser capable of suppressing a decrease in light emission efficiency of the semiconductor laser element. It is providing a device and a method for manufacturing the device.

Means for Solving the Problems and Effects of the Invention

  To achieve the above object, a nitride-based semiconductor laser device according to a first aspect of the present invention is formed on a main surface of a substrate and includes a nitride-based semiconductor device layer having a light-emitting layer, and a nitride having a light-emitting layer The first resonator end face formed at the end of the physical semiconductor element layer and the region facing the first resonator end face are extended at least at a predetermined angle with respect to the main surface (000-1). Or a reflective surface comprising a {A + B, A, -2A-B, 2A + B} surface (where A ≧ 0 and B ≧ 0, and at least one of A and B is not 0) With.

  In the nitride-based semiconductor laser device according to the first aspect of the present invention, as described above, the nitride-based semiconductor laser device is formed in the region facing the first resonator end face and extends at least at a predetermined angle with respect to the main surface (000−). 1) Since the reflecting surface (facet) having the above-mentioned plane orientation has flatness by providing a surface or a reflecting surface consisting of {A + B, A, -2A-B, 2A + B} surface, for example, the first resonance The laser light emitted from the end face of the vessel can be emitted to the outside by uniformly changing the emission direction without causing scattering on the reflecting surface. As a result, it is possible to suppress a decrease in the light emission efficiency of the semiconductor laser element.

  In the nitride semiconductor laser element according to the first aspect, preferably, the substrate has a recess formed in the main surface, and the reflecting surface is formed starting from the inner side surface of the recess. It consists of the crystal growth surface of the layer. According to this structure, the inner surface of the recess is larger than the growth rate at which the upper surface of the growth layer (the main surface of the nitride-based semiconductor device layer) grows when the nitride-based semiconductor device layer grows on the substrate. Since the growth rate at which the reflection surface composed of the crystal growth surface starting from is formed is slow, the upper surface (main surface) of the growth layer grows while maintaining flatness. Thereby, the flatness of the surface (main surface) of the semiconductor layer having the light emitting layer can be further improved as compared with the growth layer surface of the nitride-based semiconductor element layer in the case where the recess is not previously formed in the substrate. . The reason for this is considered as follows. Surfaces with a slow growth rate such as the (000-1) plane and the {A + B, A, -2A-B, 2A + B} plane have a small surface energy, while examples of a surface with a high growth rate include (1-100) Surfaces are considered to have a large surface energy. Since the surface during crystal growth is more stable when the surface energy is small, the surface energy is smaller than that of the (1-100) plane when performing crystal growth with only the (1-100) plane as the growth plane. Surfaces other than the (1-100) surface are likely to appear. As a result, the flatness of the growth surface (main surface) tends to be impaired. On the other hand, in the present invention, for example, the (000-1) plane or {A + B, A, -2A-B, 2A + B} plane having a smaller surface energy than the (1-100) plane grown as the main surface is formed. Since the plane ((1-100) plane) is grown, the surface energy of the growth plane (main surface) can be reduced compared to the case where crystal growth is performed using only the (1-100) plane as the growth plane. it can. This is thought to improve the flatness of the growth surface.

  In the nitride-based semiconductor laser device according to the first aspect, preferably, a second resonator end surface formed at an end opposite to the first resonator end surface and extending in a direction substantially perpendicular to the main surface is provided. Further prepare. If comprised in this way, the nitride type | system | group semiconductor element layer which used the 1st resonator end surface and the 2nd resonator end surface on the opposite side to a 1st resonator end surface as a pair of resonator surface can be formed. .

  In the nitride semiconductor laser element according to the first aspect, the substrate is preferably made of a nitride semiconductor. If comprised in this way, the (000-1) plane or {A + B, A, -2A-B, 2A + B} plane will be utilized using the crystal growth of a nitride-type semiconductor element layer on the board | substrate which consists of nitride type semiconductors A nitride-based semiconductor element layer having a first resonator end face made of can be easily formed.

  In the nitride-based semiconductor laser device according to the first aspect, preferably, the laser light emitted from the end face of the first resonator is emitted in a direction intersecting the emission direction of the laser light from the light emitting layer by the reflecting surface. Is changed to be incident on an optical sensor for monitoring laser light. With this configuration, laser light (sample light for monitoring the laser light intensity of the edge-emitting laser element) in which light scattering is suppressed by a reflective surface having good flatness as a crystal growth surface is guided to the optical sensor. Therefore, the laser beam intensity can be measured more accurately.

  In the nitride-based semiconductor laser device according to the first aspect, preferably, the laser beam emitted from the end face of the first resonator is emitted in the direction intersecting the emission direction of the laser beam from the light emitting layer by the reflecting surface. This is a surface emitting laser configured to vary. With this configuration, since the laser light whose light scattering is suppressed is emitted by the reflecting surface having good flatness as the crystal growth surface, it is possible to form a surface emitting laser with improved luminous efficiency. it can.

  The method for manufacturing a nitride-based semiconductor laser device according to the second aspect of the present invention includes a step of forming a first resonator end face at an end portion of a nitride-based semiconductor element layer having a light emitting layer while being formed on a main surface. And a (000-1) plane extending at a predetermined angle with respect to the main surface in a region facing the end face of the first resonator, or a {A + B, A, -2A-B, 2A + B} plane (here A ≧ 0 and B ≧ 0, and at least one of A and B is an integer that is not 0), and a main surface at the end opposite to the first resonator end surface, Forming a second resonator end face extending in a direction substantially perpendicular to the surface.

  In the method for manufacturing a nitride based semiconductor laser device according to the second aspect of the present invention, as described above, the step of forming the first resonator end face at the end of the nitride based semiconductor device layer having the light emitting layer, (1) A reflective surface composed of a (000-1) plane extending at a predetermined angle with respect to the main surface or a {A + B, A, -2A-B, 2A + B} plane is formed in a region facing the resonator end face. Unlike the case of forming a reflective surface (inclined end surface) having a fine uneven shape by ion beam etching or the like, it is favorable for the reflective surface (facet) having the above surface orientation. Flatness is obtained. As a result, for example, the laser light emitted from the end face of the first resonator can be emitted to the outside by uniformly changing the emission direction without causing scattering on the reflection surface, so that a decrease in light emission efficiency is suppressed. A semiconductor laser element can be formed. In addition, since a reflective surface that is inclined with respect to the end face of the first resonator is formed simultaneously with the crystal growth of the nitride-based semiconductor element layer, after the flat semiconductor element layer is grown on the substrate, resonance occurs, for example, by ion beam etching. Unlike the case of forming a reflecting surface (tilted end surface) inclined at a predetermined angle with respect to the end surface of the vessel (for example, the light emitting surface side), it is also possible to suppress the semiconductor laser element manufacturing process from becoming complicated.

  In the method for manufacturing a nitride-based semiconductor laser device according to the second aspect, preferably, the step of forming the first resonator end surface and the step of forming the second resonator end surface include crystal growth of a nitride-based semiconductor element layer. Thus, at least one of the first resonator end surface and the second resonator end surface is formed, and at least one of the first resonator end surface and the second resonator end surface is formed by etching. With this configuration, it is possible to perform the end face formation of the nitride semiconductor element layer by crystal growth and the end face formation by etching, so that the nitride system formed on a substrate with poor cleavage, such as a GaN substrate. A resonator end face (first resonator end face or second resonator end face) can be easily formed at the end of the region including the light emitting layer of the semiconductor element layer. Further, by controlling the crystal growth and etching conditions, it is possible to easily form a resonator end face (first resonator end face or second resonator end face) extending in a direction substantially perpendicular to the main surface. .

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

  FIG. 1 is a cross-sectional view for explaining a schematic configuration of a semiconductor laser device according to the present invention. Referring to FIG. 1, before describing a specific embodiment of the present invention, a schematic configuration of a semiconductor laser element according to the present invention will be described by taking a semiconductor laser element 10 as an example.

  As shown in FIG. 1, the semiconductor laser device 10 has an active layer 2 formed on a first semiconductor 1. A second semiconductor 3 is formed on the active layer 2. A first electrode 4 is formed on the lower surface of the first semiconductor 1, and a second electrode 5 is formed on the second semiconductor 3. The first semiconductor 1 is an example of the “substrate” and “nitride-based semiconductor element layer” of the present invention, and the active layer 2 is the “light emitting layer” and “nitride-based semiconductor element layer” of the present invention. It is an example. The second semiconductor 3 is an example of the “nitride-based semiconductor element layer” in the present invention.

  Here, generally, an active layer 2 having a band gap smaller than the band gap of the first semiconductor 1 and the second semiconductor 3 is formed between the first semiconductor 1 and the second semiconductor 3 to form a double heterostructure. By forming, it is possible to easily confine carriers in the active layer 2 and to improve the light emission efficiency of the semiconductor laser device 10 (active layer 2). Further, by making the active layer 2 have a single quantum well (SQW) structure or a multiple quantum well (MQW) structure, it is possible to further improve the light emission efficiency. In the case of this quantum well structure, since the thickness of the well layer is small, it is possible to suppress deterioration of the crystallinity of the well layer even when the well layer has strain. In addition, even if the well layer has a compressive strain in the in-plane direction of the main surface 2a of the active layer 2 or has a tensile strain in the in-plane direction, the deterioration of crystallinity is suppressed. Is done. The active layer 2 may be undoped or doped.

  In the present invention, the first semiconductor 1 may be composed of a substrate or a semiconductor layer, or may be composed of both a substrate and a semiconductor layer. Moreover, when the 1st semiconductor 1 is comprised by both a board | substrate and a semiconductor layer, a board | substrate is the opposite side to the side in which the 2nd semiconductor 3 of the 1st semiconductor 1 is formed (lower surface side of the 1st semiconductor 1). Formed. The substrate may be a growth substrate or may be used as a support substrate for supporting the semiconductor layer on the growth surface (main surface) of the semiconductor layer after the semiconductor layer is grown.

As the substrate, a GaN substrate or an α-SiC substrate can be used. A nitride-based semiconductor element layer having the same main surface as the substrate is formed on the GaN substrate and the α-SiC substrate. For example, nitride-based semiconductor element layers having a-plane and m-plane as main surfaces are formed on the a-plane and m-plane of the α-SiC substrate, respectively. Alternatively, an r-plane sapphire substrate on which a nitride semiconductor having an a-plane as a main surface is formed may be used as the substrate. In addition, a LiAlO ₂ substrate or a LiGaO ₂ substrate on which a nitride-based semiconductor element layer having main surfaces of the a-plane and m-plane can be used.

  In the pn junction type semiconductor laser device 10, the first semiconductor 1 and the second semiconductor 3 have different conductivity. The first semiconductor 1 may be p-type and the second semiconductor 3 may be n-type, or the first semiconductor 1 may be n-type and the second semiconductor 3 may be p-type.

  The first semiconductor 1 and the second semiconductor 3 may include a cladding layer (not shown) having a band gap larger than that of the active layer 2. The first semiconductor 1 and the second semiconductor 3 may each include a clad layer and a contact layer (not shown) in order from the active layer 2 side. In this case, the contact layer preferably has a smaller band gap than the cladding layer.

  As the quantum well active layer 2, GaInN can be used as the well layer, and AlGaN, GaN, and GaInN having a larger band gap than the well layer can be used as the barrier layer. Moreover, GaN and AlGaN can be used for the cladding layer and the contact layer.

  FIG. 2 is a diagram showing the crystal orientation of the nitride-based semiconductor and the range in the normal direction of the main surface of the substrate when the semiconductor laser device is formed using the manufacturing process according to the present invention. Next, with reference to FIG. 2, the plane orientation of the substrate when the semiconductor laser element is formed using the method for forming a nitride-based semiconductor element layer of the present invention will be described.

  As shown in FIG. 2, the normal direction of the main surface 6a of the substrate 6 is a line 300 ([C + D, C, -2C-D] connecting the [11-20] direction and the [10-10] direction, respectively. , 0] direction (C ≧ 0 and D ≧ 0, and at least one of C and D is not 0)), and [11-20] direction and substantially [11-2-5] Line 400 ([1, 1, −2, −E] direction (0 ≦ E ≦ 5)) and a line connecting the [10-10] direction and the substantially [10-1-4] direction. 500 ([1, −1, 0, −F] direction (0 ≦ F ≦ 4)) and a line 600 (approximately connecting the [11-2-5] direction and the [10-1-4] direction) [G + H, G, -2G-H, -5G-4H] direction (G ≧ 0 and H ≧ 0, and an integer in which at least one of G and H is not 0) In the range (hatched region by hatching) enclosed by).

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

(First embodiment)
FIG. 3 is a perspective view showing the structure of the surface-emitting nitride-based semiconductor laser device according to the first embodiment of the present invention. 4 and 5 are cross-sectional views for explaining the structure of the surface emitting nitride-based semiconductor laser device shown in FIG. First, the structure of the surface emitting nitride semiconductor laser element 30 according to the first embodiment will be described with reference to FIGS.

  In the surface emitting nitride-based semiconductor laser device 30 according to the first embodiment, as shown in FIGS. 3 and 4, the surface-emitting nitride semiconductor laser device 30 is formed on an n-type GaN substrate 11 having a thickness of about 100 μm and has a thickness of about 3 μm to about 4 μm. A semiconductor laser element layer 12 having a thickness of about 3.1 μm is formed on a base layer 40 made of AlGaN having a thickness. The n-type GaN substrate 11 and the semiconductor laser element layer 12 are examples of the “substrate” and the “nitride-based semiconductor element layer” in the present invention, respectively. Further, as shown in FIG. 4, the semiconductor laser element layer 12 is formed so that the length L1 between the laser element end portions (direction A) is about 1560 μm.

  Here, in the first embodiment, as shown in FIG. 4, the semiconductor laser element layer 12 is formed on the main surface composed of the (1-10-4) plane of the n-type GaN substrate 11 with the base layer 40 interposed therebetween. Is formed. Further, the semiconductor laser element layer 12 includes a light emitting surface 30a and a light reflecting surface 30b that are substantially perpendicular to the main surface of the n-type GaN substrate 11 in the cavity direction (A direction) that is the [1-101] direction. Are formed respectively. The light emitting surface 30a and the light reflecting surface 30b are examples of the “first resonator end surface” and the “second resonator end surface” in the present invention, respectively. In the present invention, the light emitting surface 30a and the light reflecting surface 30b are distinguished by the magnitude relationship between the intensity of the laser light emitted from the respective resonator end surfaces on the light emitting side and the light reflecting side. That is, the side with a relatively high laser beam emission intensity is the light emission surface 30a, and the side with a relatively low laser beam emission intensity is the light reflection surface 30b.

  In the first embodiment, the base layer 40 is formed with cracks 41 that are formed during crystal growth of the base layer 40 and extend in a stripe shape in the [11-20] direction of the n-type GaN substrate 11. . As shown in FIG. 4, the light emitting surface 30a of the semiconductor laser element layer 12 is crystal-grown so as to take over the inner side surface 41a of the crack 41 of the underlayer 40 when the semiconductor laser element layer 12 described later is formed ( 1-101) plane. The light reflecting surface 30b of the semiconductor laser element layer 12 is formed by a (−110-1) plane that is an end surface perpendicular to the [−110-1] direction (A1 direction in FIG. 4). The crack 41 is an example of the “recessed portion” in the present invention, and the inner side surface 41a is an example of the “inner side surface of the recessed portion” in the present invention.

  In the first embodiment, when the base layer 40 made of AlGaN is crystal-grown, a crack 41 as a recess is formed in the base layer 40 by utilizing the lattice constant difference between the n-type GaN substrate 11 and the base layer 40. However, after the underlayer 40 is crystal-grown, a recess (groove-shaped depression) may be formed from the surface side of the underlayer 40 by mechanical scribe, laser scribe, dicing, etching, or the like. Moreover, when forming a recessed part using the said method, it is good also considering the base layer 40 as GaN which has the lattice constant similar to the n-type GaN board | substrate 11 which is a board | substrate (base substrate). Furthermore, as will be described later, a recess (groove 150 in the seventh embodiment) may be formed directly on the surface side of the n-type GaN substrate 11 by mechanical scribe, laser scribe, dicing, etching, or the like. .

In the first embodiment, as shown in FIG. 4, the semiconductor laser element layer 12 has a region facing the light emitting surface 30a in the [1-101] direction (A2 direction) with respect to the light emitting surface 30a. Thus, a reflecting surface 30c extending in a direction inclined by an angle θ ₁ (= about 65 °) is formed. Further, the reflective surface 30c is a facet (growth surface) composed of a (000-1) surface that is crystal-grown starting from the upper end portion of the inner side surface 41b of the crack 41 of the underlayer 40 when the semiconductor laser element layer 12 described later is formed. It is formed by. Thereby, in the surface emitting nitride semiconductor laser element 30, as shown in FIG. 4, the laser light emitted in the A2 direction from the light emitting surface 30a of the light emitting layer 15 described later is reflected on the light emitting surface by the reflecting surface 30c. It is configured to be able to emit to the outside by changing the emitting direction in a direction inclined by an angle θ ₂ (= about 40 °) with respect to 30a. The inner side surface 41b is an example of the “inner side surface of the recess” in the present invention. As shown in FIG. 4, an end face 30 d made of the (1-101) plane of the semiconductor laser element layer 12 is formed at the end in the A2 direction of the surface emitting nitride semiconductor laser element 30.

Further, as shown in FIGS. 3 and 4, the semiconductor laser element layer 12 includes a buffer layer 13, an n-type cladding layer 14, a light emitting layer 15, a p-type cladding layer 16 and a p-type contact layer 17. It is out. Specifically, as shown in FIG. 4, the upper layer of the underlayer 40 formed on the n-type GaN substrate 11 is made of undoped Al _0.01 Ga _0.99 N having a thickness of about 1.0 μm. A buffer layer 13 and an n-type cladding layer 14 made of Ge-doped Al _0.07 Ga _0.93 N having a thickness of about 1.9 μm are formed.

A light emitting layer 15 is formed on the n-type cladding layer 14. As shown in FIG. 5, the light emitting layer 15 includes an n-side carrier block made of Al _0.2 Ga _0.8 N having a thickness of about 20 nm in order from the side close to the n-type cladding layer 14 (see FIG. 4). A layer 15a, an n-side light guide layer 15b made of undoped In _0.02 Ga _0.98 N having a thickness of about 20 nm, an MQW active layer 15e, and an undoped In _0.01 Ga having a thickness of about 0.8 μm. _The p-side light guide layer 15 f made of _0.99 N and the carrier block layer 15 g made of Al _0.25 Ga _0.75 N having a thickness of about 20 nm are formed. The MQW active layer 15e includes three quantum well layers 15c made of undoped In _0.15 Ga _0.85 N having a thickness of about 2.5 nm and undoped In _0.02 Ga _0. Three quantum barrier layers 15d made of ₉₈ N are alternately stacked. The n-type cladding layer 14 has a larger band gap than the MQW active layer 15e. Further, an optical guide layer having a band gap intermediate between the n-side carrier block layer 15a and the MQW active layer 15e may be formed between the n-side carrier block layer 15a and the MQW active layer 15e. The MQW active layer 15e may be formed with a single layer or an SQW structure.

As shown in FIGS. 3 and 4, on the light emitting layer 15, a flat portion and a convex portion formed to protrude upward (C2 direction) from a substantially central portion of the flat portion and having a thickness of about 1 μm. A p-type cladding layer 16 made of Mg-doped Al _0.07 Ga _0.93 N is formed. The p-type cladding layer 16 has a larger band gap than the MQW active layer 15e. A p-type contact layer 17 made of undoped In _0.07 Ga _0.93 N having a thickness of about 3 nm is formed on the convex portion of the p-type cladding layer 16. Further, the convex portion of the p-type cladding layer 16 and the p-type contact layer 17 form a stripe shape (elongated) in the resonator direction (direction A in FIG. 3) as an optical waveguide of the surface-emitting nitride semiconductor laser device 30. Is formed. The buffer layer 13, the n-type cladding layer 14, the light emitting layer 15, the p-type cladding layer 16, and the p-type contact layer 17 are examples of the “nitride-based semiconductor element layer” in the present invention.

As shown in FIG. 3, SiO ₂ having a thickness of about 200 nm so as to cover the upper surface of the flat portion other than the convex portion of the p-type cladding layer 16 of the semiconductor laser element layer 12 and both side surfaces of the ridge portion 31. A current blocking layer 18 made of is formed.

  Further, on the upper surfaces of the current blocking layer 18 and the p-type contact layer 17, a Pt layer having a thickness of about 5 nm and a Pd layer having a thickness of about 100 nm are arranged in order from the side closer to the upper surface of the p-type contact layer 17. A p-side electrode 19 made of an Au layer having a thickness of about 150 nm is formed.

  Further, as shown in FIGS. 3 and 4, on the back surface of the n-type GaN substrate 11, an Al layer having a thickness of about 10 nm and a thickness of about 20 nm are sequentially formed from the side closer to the n-type GaN substrate 11. An n-side electrode 20 composed of a Pt layer and an Au layer having a thickness of about 300 nm is formed. As shown in FIG. 4, the n-side electrode 20 is formed on the entire surface of the back surface of the n-type GaN substrate 11 so as to extend to both sides in the direction of arrow A of the surface-emitting nitride semiconductor laser element 30. .

  6 to 10 are a sectional view and a plan view, respectively, for explaining the manufacturing process of the surface-emitting nitride semiconductor laser device according to the first embodiment shown in FIG. A manufacturing process for the surface-emitting nitride semiconductor laser device 30 according to the first embodiment is now described with reference to FIGS.

First, as shown in FIG. 6, an underlying layer 40 made of AlGaN having a thickness of about 3 μm to about 4 μm is grown on an n-type GaN substrate 11 using metal organic chemical vapor deposition (MOCVD). Note that when the underlying layer 40 is crystal-grown, since the lattice constant _{c 2} of the underlayer 40 made of AlGaN than the lattice constant _{c 1} of the n-type GaN substrate 11 is small _(c 1> _{c 2),} reaches a predetermined thickness The underlying layer 40 generates a tensile stress R inside the underlying layer 40 in an attempt to match the lattice constant c ₁ of the n-type GaN substrate 11. As a result, as the underlayer 40 locally shrinks in the A direction, cracks 41 as shown in FIGS. 6 and 7 are formed in the underlayer 40. Here, since the difference in the c-axis lattice constant between GaN and AlGaN is larger than the difference in the a-axis lattice constant between GaN and AlGaN, the crack 41 is formed between the (0001) plane and the n-type GaN substrate 11. It is easy to form so that it may extend in a stripe form along the [11-20] direction (B direction) parallel to the (1-10-4) plane of the main surface of. FIG. 6 schematically shows a state in which the crack 41 is spontaneously formed in the underlayer 40.

  In the first embodiment, as shown in FIG. 6, when the crack 41 is formed in the underlayer 40, the crack 41 has an inner surface that reaches the vicinity of the interface between the underlayer 40 and the n-type GaN substrate 11. 41a is formed. The inner side surface 41 a is formed substantially perpendicular to the main surface made of the (1-10-4) plane of the n-type GaN substrate 11. Here, since the crack 41 is formed using the tensile stress R (see FIG. 6) generated in the underlayer 40, an external processing technique (for example, mechanical scribe, laser scribe, dicing and etching) is used. Unlike the case where the concave portion is formed, the crack 41 can be easily aligned with the [11-20] direction. As a result, since the crack 41 can be formed extremely flat, the semiconductor laser element layer 12 having a flat end face ((1-101) face) can be easily grown.

  In the first embodiment, since the crack 41 reaching the vicinity of the main surface of the n-type GaN substrate 11 is formed in the underlayer 40 as described above, the underlayer 40 having a lattice constant different from that of the n-type GaN substrate 11 is formed. The lattice distortion of can be released. Therefore, the crystal quality of the underlayer 40 is improved, and the semiconductor laser element layer 12 formed on the underlayer 40 can be in a high-quality crystal state. As a result, the electrical characteristics of the n-type clad layer 14, the n-side carrier block layer 15a, the carrier block layer 15g, the p-type clad layer 16 and the p-type contact layer 17 formed in the steps described later are improved. It is possible to suppress light absorption in the layer. Furthermore, the internal loss of the light emitting layer 15 (n-side carrier block layer 15a, n-side light guide layer 15b, MQW active layer 15e, p-side light guide layer 15f, and carrier block layer 15g) is reduced, and the light emission of the light-emitting layer 15 is reduced. Efficiency can be improved. In the first embodiment, the crack 41 reaching the vicinity of the main surface of the n-type GaN substrate 11 is formed in the base layer 40, but the base layer 40 is formed in the thickness direction of the base layer 40 (C2 direction in FIG. 6). You may make it form the groove part of the depth equivalent to this thickness. Even if comprised in this way, since the internal strain of the foundation layer 40 can be released by the groove portion having a depth corresponding to the thickness of the foundation layer 40, the same effect as the case of forming the crack 41 can be obtained. .

  Next, as shown in FIG. 8, the buffer layer 13, the n-type cladding layer 14, the light emitting layer 15 (see FIG. 5 for details), p on the base layer 40 on which the crack 41 is formed, using MOCVD. A semiconductor cladding layer 16 and a p-type contact layer 17 are sequentially grown to form a semiconductor laser element layer 12.

Specifically, in the formation of the semiconductor laser element layer 12, first, TMGa (trimethylgallium) as a Ga source and TMAl (trimethylaluminum) as an Al source while the substrate temperature is maintained at a growth temperature of about 1000 ° C. A carrier gas composed of H ₂ containing) is supplied into the reaction furnace to grow the buffer layer 13 on the n-type GaN substrate 11. Next, a carrier gas composed of H ₂ containing TMGa and TMAl and GeH ₄ (monogermane) which is a raw material of Ge impurities for obtaining n-type conductivity is supplied into the reaction furnace, and the buffer layer 13 An n-type cladding layer 14 is grown thereon. Thereafter, an H ₂ gas containing TMGa and TMAl is supplied into the reaction furnace to grow the n-side carrier block layer 15 a on the n-type cladding layer 14.

Next, with the substrate temperature lowered to a growth temperature of about 850 ° C. and maintained in a nitrogen gas atmosphere in which NH ₃ gas is supplied into the reaction furnace, the Ga source TEGa (triethylgallium) and In source A certain TMIn (trimethylindium) is supplied to grow the n-side light guide layer 15b, the MQW active layer 15e, and the p-side light guide layer 15f. Then, TMGa and TMAl are supplied into the reaction furnace to grow the carrier block layer 15g. Thereby, the light emitting layer 15 (refer FIG. 5) is formed.

Next, with the substrate temperature raised to a growth temperature of about 1000 ° C. and maintained in a hydrogen gas and nitrogen gas atmosphere in which NH ₃ gas is supplied into the reaction furnace, the source material of Mg, which is a p-type impurity, is used. A certain Mg (C ₅ H ₅ ) ₂ (cyclopentanedienylmagnesium), TMGa as a Ga raw material, and TMAl as an Al raw material are supplied to grow a p-type cladding layer 16 on the light emitting layer 15. Thereafter, TEGa as the Ga source and TMIn as the In source are supplied in a nitrogen gas atmosphere in which NH ₃ gas is supplied into the reactor while the substrate temperature is again lowered to the growth temperature of about 850 ° C. Then, the p-type contact layer 17 is grown. In this way, the semiconductor laser element layer 12 is formed on the base layer 40.

Here, in the first embodiment, as shown in FIG. 9, when the semiconductor laser element layer 12 is grown on the underlayer 40, the inner side surface 41a of the crack 41 extending in a stripe shape in the B direction (see FIG. 7). The crystal grows while forming an end surface ((1-101) plane) extending in the [1-10-4] direction (C2 direction) so as to take over the inner side surface 41a of the crack 41, starting from the upper end portion of. As a result, a light emitting surface 30 a composed of a (1-101) plane is formed in the semiconductor laser element layer 12. At the same time, the semiconductor laser element layer 12 extends in a direction inclined at an angle θ ₁ (= about 65 °) with respect to the main surface of the n-type GaN substrate 11 starting from the upper end portion of the inner side surface 41b of the crack 41 ( A facet (growth surface) composed of the (000-1) plane is formed. As a result, the semiconductor laser element layer 12 is formed with a reflective surface 30c that is formed of the (000-1) plane and forms an obtuse angle with respect to the upper surface (main surface) of the semiconductor laser element layer 12. In the process of crystal growth of the semiconductor laser element layer 12, the surface (upper surface) of the semiconductor laser element layer 12 is higher than the growth rate of the portion where the (1-101) plane and the (000-1) plane are formed. Since the growth rate of growth in the direction of the arrow C2 (see FIG. 8) is fast, the flatness of the main surface (upper surface) of the semiconductor laser element layer 12 can also be improved.

  Then, p-type annealing is performed in a nitrogen gas atmosphere under a temperature condition of about 800 ° C.

  Next, as shown in FIG. 3, after forming a resist pattern on the upper surface of the p-type contact layer 17 by photolithography, dry etching or the like is performed using the resist pattern as a mask to form the ridge portion 31. . Thereafter, the current blocking layer 18 is formed so as to cover the upper surface of the flat portion other than the convex portion of the p-type cladding layer 16 and both side surfaces of the ridge portion 31. Also, as shown in FIGS. 3 and 10, a p-side electrode 19 is formed on the current blocking layer 18 and the p-type contact layer 17 where the current blocking layer 18 is not formed by using a vacuum deposition method. FIG. 10 shows a cross-sectional structure along the resonator direction (A direction) of the semiconductor laser element at the position where the p-type contact layer 17 is formed (near the ridge portion 31).

  Thereafter, as shown in FIG. 10, the back surface of the n-type GaN substrate 11 is polished so that the thickness of the n-type GaN substrate 11 is about 100 μm, and then the n-type GaN substrate 11 is formed by vacuum evaporation. An n-side electrode 20 is formed on the back surface so as to be in contact with the n-type GaN substrate 11.

  In the first embodiment, as shown in FIG. 10, the position where a predetermined resonator end face is to be formed is a direction (arrow C <b> 1) from the surface side (upper surface side) of the semiconductor laser element layer 12 to the n-type GaN substrate 11. By performing dry etching in the direction), the groove part 42 having a substantially (−110-1) plane on one side surface of the semiconductor laser element layer 12 is formed. As a result, the substantially (−110-1) surface, which is one side surface of the groove 42, is easily formed as the light reflecting surface 30 b of the pair of resonator end surfaces in the surface emitting nitride semiconductor laser element 30. . Further, the substantially (1-101) plane that is the other side surface of the groove 42 is formed as the end face 30 d of the surface emitting nitride semiconductor laser element 30. In addition, the groove part 42 is formed so as to extend in the [11-20] direction (B direction) substantially parallel to the direction in which the crack 41 extends in a plan view.

  Then, as shown in FIG. 10, linear scribe grooves 43 are formed in the groove portions 42 in parallel with the groove portions 42 of the n-type GaN substrate 11 by laser scribe or mechanical scribe. In this state, as shown in FIG. 10, by applying a load with the back surface side of the n-type GaN substrate 11 as a fulcrum so that the front surface side (upper side) of the wafer opens, the wafer is separated at the position of the scribe groove 43. To do. In addition, as shown in FIG. 4, the groove part 42 of the n-type GaN substrate 11 becomes a step part 11a formed under the light reflecting surface 30b and the end face 30d after the element division.

  Thereafter, the element is divided into chips along the resonator direction (A direction), whereby the surface emitting nitride semiconductor laser element 30 according to the first embodiment shown in FIGS. 3 and 4 is formed. The

In the first embodiment, as described above, the main surface of the n-type GaN substrate 11 ((1-10-4) is formed in the region facing the light emitting surface 30a formed at the end of the semiconductor laser element layer 12. ) Surface), the reflective surface 30c composed of the (000-1) surface extending at an angle θ ₁ (= about 65 °) is inclined, so that the reflective surface 30c composed of the (000-1) surface has flatness. Therefore, the laser light emitted from the light emitting surface 30a is emitted to the outside (above the surface-emitting nitride semiconductor laser element 30) while changing the emitting direction uniformly without causing scattering at the reflecting surface 30c. Can be made. As a result, it is possible to suppress a decrease in the light emission efficiency of the surface emitting nitride semiconductor laser element 30.

In the first embodiment, the reflective surface 30c that is inclined with respect to the light emitting surface 30a is formed simultaneously with the crystal growth of the semiconductor laser device layer 12, so that a flat semiconductor device layer is grown on the n-type GaN substrate 11. Unlike the case where a reflective surface inclined by an angle θ ₁ (= about 65 °) with respect to the light emitting surface 30a is formed by ion beam etching or the like later, the manufacturing process of the semiconductor laser element is prevented from becoming complicated. be able to.

  Further, in the first embodiment, the n-type GaN substrate 11 has the crack 41 formed on the main surface of the n-type GaN substrate 11, and the reflection surface 30 c of the semiconductor laser element layer 12 is used as the crack of the n-type GaN substrate 11. When the semiconductor laser element layer 12 is crystal-grown on the n-type GaN substrate 11 by constituting the crystal growth surface of the semiconductor laser element layer 12 formed starting from the inner side surface 41b of 41, the growth layer Since the growth rate at which the reflecting surface 30c formed of the crystal growth surface starting from the inner side surface 41b of the crack 41 is formed is slower than the growth rate at which the upper surface (the main surface of the semiconductor laser device layer 12) grows, the growth layer The upper surface (main surface) of the substrate grows while maintaining flatness. Thereby, the flatness of the surface of the semiconductor layer having the light emitting layer can be further improved as compared with the growth layer surface of the semiconductor laser element layer 12 when the crack 41 is not formed in the n-type GaN substrate 11 in advance. .

  Further, since the (1-101) plane has a slower growth rate than the main surface (upper surface) of the semiconductor laser element layer 12, the light emitting surface 30a can be easily formed by crystal growth.

  In the first embodiment, the semiconductor laser element layer 12 having a light emitting layer is formed at the end opposite to the light emitting surface 30 a and extends in a direction substantially perpendicular to the main surface of the n-type GaN substrate 11. By providing the light emitting surface 30b, it is possible to form the semiconductor laser element layer 12 having the light emitting surface 30a and the light emitting surface 30b opposite to the light emitting surface 30a as a pair of resonator surfaces.

  In the first embodiment, the semiconductor laser element is formed on the n-type GaN substrate 11 made of a nitride semiconductor by configuring the substrate to be an n-type GaN substrate 11 made of a nitride semiconductor such as GaN. By using the crystal growth of the layer 12, the semiconductor laser element layer 12 having both the light emitting surface 30a composed of the (1-101) plane and the reflecting surface 30c composed of the (000-1) plane can be easily formed. it can.

  Further, in the first embodiment, by forming the light reflecting surface 30b by etching, the resonator end surface can be easily formed on the end portion of the semiconductor laser element layer 12 formed on a substrate with poor cleavage such as a GaN substrate. Can be formed. Further, by controlling the etching conditions, the (−110-1) plane easily extends in a direction ([1-10-4] direction) substantially perpendicular to the main surface of the n-type GaN substrate 11. The light reflecting surface 30b can be formed.

(Second Embodiment)
FIG. 11 is a sectional view showing the structure of a surface-emitting nitride-based semiconductor laser device according to the second embodiment of the present invention. FIG. 12 is a cross-sectional view for explaining a manufacturing process of the surface emitting nitride-based semiconductor laser device according to the second embodiment shown in FIG. With reference to FIGS. 7, 11 and 12, the manufacturing process of the surface emitting nitride semiconductor laser device 50 according to the second embodiment differs from the first embodiment in that the m-plane ((1-100) A case will be described in which the semiconductor laser element layer 12 is formed after the base layer 40 made of AlGaN is formed on the n-type GaN substrate 51 having the main surface consisting of the surface. The n-type GaN substrate 51 is an example of the “substrate” in the present invention.

  In the surface-emitting nitride semiconductor laser device 50 according to the second embodiment, as shown in FIG. 11, the n-type GaN substrate 51 having a main surface composed of an m-plane ((1-100) plane) is A semiconductor laser element layer 12 having the same structure as that of the first embodiment is formed.

  Here, in the second embodiment, the semiconductor laser element layer 12 is formed with a light emitting surface 50 a and a light reflecting surface 50 b that are substantially perpendicular to the main surface of the n-type GaN substrate 51. The light emitting surface 50a and the light reflecting surface 50b are examples of the “first resonator end surface” and the “second resonator end surface” in the present invention, respectively. Further, the light emitting surface 50a is formed by a (000-1) plane in which crystals are grown so as to take over the inner side surface 41a of the crack 41 of the foundation layer 40. The light reflecting surface 50b is formed by a (0001) plane perpendicular to the [0001] direction (A1 direction in FIG. 11).

In the second embodiment, as shown in FIG. 11, the semiconductor laser element layer 12 has a region facing the light emitting surface 50a in the [000-1] direction (A2 direction) with respect to the light emitting surface 50a. Thus, a reflection surface 50c extending in a direction inclined by an angle θ ₃ (= about 62 °) is formed. The reflecting surface 50c is formed by a facet composed of a (1-101) plane accompanying crystal growth when the semiconductor laser element layer 12 is formed. As a result, in the surface emitting nitride semiconductor laser element 50, as shown in FIG. 11, the laser light emitted in the A2 direction from the light emitting surface 50a of the light emitting layer 15 is reflected on the light emitting surface 50a by the reflecting surface 50c. On the other hand, the emission direction can be changed in a direction inclined by an angle θ ₄ (= about 34 °). As shown in FIG. 11, an end face 50 d made of the (000-1) plane of the semiconductor laser element layer 12 is formed at the end in the A2 direction of the surface emitting nitride semiconductor laser element 50.

  The element structure of the semiconductor laser element layer 12 of the surface emitting nitride semiconductor laser element 50 according to the second embodiment is the same as that of the first embodiment.

  Further, in the manufacturing process of the surface emitting nitride semiconductor laser device 50 according to the second embodiment, as shown in FIG. 12, a semiconductor laser is formed on the underlayer 40 by using the same manufacturing process as in the first embodiment. The element layer 12 is formed.

Here, in the second embodiment, as shown in FIG. 12, when the semiconductor laser element layer 12 is grown on the base layer 40, the semiconductor laser element layer 12 is striped in the B direction (see FIG. 7). Starting from the upper end of the inner side surface 41a of the extending crack 41, the crystal grows while forming a (000-1) plane extending in the [1-100] direction (C2 direction) so as to take over the inner side surface 41a of the crack 41. As a result, the semiconductor laser element layer 12 is formed with a light emitting surface 50a composed of a (000-1) plane. At the same time, the semiconductor laser element layer 12 is inclined at an angle θ ₃ (= about 62 °) with respect to the main surface of the n-type GaN substrate 51 starting from the upper end portion of the inner surface 41b of the crack 41 (1-62). 101) A facet consisting of a surface is formed. As a result, the semiconductor laser element layer 12 is formed with a reflective surface 50c that is formed of the (1-101) plane and forms an obtuse angle with respect to the upper surface (main surface) of the semiconductor laser element layer 12. In the process of crystal growth of the semiconductor laser element layer 12, the surface (upper surface) of the semiconductor laser element layer 12 is higher than the growth rate of the portion where the (000-1) plane and (1-101) plane are formed. Since the growth rate in the direction of arrow C2 (see FIG. 12) is high, not only the flatness of the (000-1) plane and the (1-101) plane but also the flatness of the surface (upper surface) of the semiconductor laser element layer 12 It can also improve the property.

  In the second embodiment, dry etching is performed in a direction (arrow C1 direction) where the position where a predetermined resonator end face is to be formed reaches from the surface side (upper surface side) of the semiconductor laser element layer 12 to the n-type GaN substrate 51. As a result, the groove 52 having a substantially (0001) plane on one side surface of the semiconductor laser element layer 12 is formed. Thereby, one side surface of the groove 52 is easily formed as the light reflecting surface 50 b of the surface emitting nitride semiconductor laser element 50. In addition, the substantially (000-1) plane that is the other side surface of the groove 52 is formed as the end face 50 d of the surface emitting nitride semiconductor laser element 50. The groove 52 is formed so as to extend in the [11-20] direction (B direction) substantially parallel to the direction in which the crack 41 extends when seen in a plan view.

  Then, as shown in FIG. 12, a scribe groove 53 is formed in the groove 52 in parallel with the groove 52 of the n-type GaN substrate 51 (perpendicular to the paper surface of FIG. 12) by laser scribe or mechanical scribe. In this state, the wafer is separated at the position of the scribe groove 53 as shown in FIG. As shown in FIG. 11, the groove 52 of the n-type GaN substrate 51 becomes a stepped portion 51a formed below the light reflecting surface 50b and the end surface 50d after the element is divided.

  Thereafter, the device is divided into chips along the resonator direction (A direction), whereby the surface emitting nitride semiconductor laser device 50 according to the second embodiment shown in FIG. 11 is formed.

In the second embodiment, as described above, the angle θ with respect to the light emitting surface 50 a formed at the end of the semiconductor laser element layer 12 and the m-plane ((1-100) plane) of the n-type GaN substrate 51. ₃ (= about 62 °) and the reflecting surface 50c made of the (1-101) plane extending at an inclination, the reflecting surface 50c made of the (1-101) plane has flatness, and thus the light emitting surface 50a. The laser beam emitted from the laser beam can be emitted to the outside (above the surface-emitting nitride-based semiconductor laser device 50) with the emission direction uniformly changed without causing scattering at the reflecting surface 50c. As a result, it is possible to suppress a reduction in the light emission efficiency of the surface emitting nitride semiconductor laser element 50.

  In the second embodiment, the inner surface 41a of the crack 41 is configured to include the (000-1) plane, so that light is emitted from the (000-1) plane on the main surface of the n-type GaN substrate 51. When the semiconductor laser device layer 12 having the surface 50a is formed, the (000-1) surface of the semiconductor laser device layer 12 is formed so as to take over the (000-1) surface of the inner surface 41a of the crack 41. The light emitting surface 50a can be easily formed on the n-type GaN substrate 51.

  In the second embodiment, the light emitting surface 50a facing the reflecting surface 50c made of the (1-101) surface of the semiconductor laser element layer 12 is made to be made of the (000-1) surface, whereby n Compared to the case where the light exit surface 50a not corresponding to the (000-1) plane is formed on the n-type GaN substrate 51, the light exit surface 50a composed of the (000-1) plane is formed on the n-type GaN substrate 51. In this case, the surface (upper surface) of the growth layer can be formed so as to ensure flatness. Further, since the (000-1) plane has a slower growth rate than the main surface (upper surface) of the semiconductor laser element layer 12, the light emitting surface 50a can be easily formed by crystal growth.

  In the second embodiment, the semiconductor element layer is formed by forming the semiconductor laser element layer 12 on the n-type GaN substrate 51 having a main surface composed of a nonpolar plane (m-plane ((1-100) plane)). An internal electric field such as a piezo electric field and spontaneous polarization generated in the (light emitting layer 15) can be reduced. Thereby, the heat generation of the semiconductor laser element layer 12 (light emitting layer 15) including the vicinity of the resonator end face (light emitting surface 50a) is further suppressed, so that the surface emitting nitride semiconductor laser element with improved light emission efficiency is obtained. 50 can be formed. The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

[Example]
13 and 14 are photomicrographs obtained by observing the state of crystal growth of the semiconductor layer on the n-type GaN substrate in the manufacturing process of the second embodiment shown in FIG. 11 using a scanning electron microscope. With reference to FIG. 7, FIG. 13 and FIG. 14, an experiment conducted for confirming the effect of the second embodiment will be described.

  In this confirmation experiment, first, an MOCVD method is used on an n-type GaN substrate having a main surface composed of an m-plane ((1-100) plane) using the same manufacturing process as that of the second embodiment. An underlayer made of AlGaN having a thickness of 3 μm to 4 μm was formed. At this time, cracks as shown in FIGS. 13 and 14 were formed in the underlayer due to the difference in lattice constant between the n-type GaN substrate and the underlayer. At this time, it was confirmed that the crack formed a (000-1) plane extending in a direction perpendicular to the main surface of the n-type GaN substrate, as shown in FIG. Similarly to the case shown in FIG. 7, the crack is equivalent to the [11-20] direction (corresponding to the B direction in FIG. 7) perpendicular to the [0001] direction (corresponding to the A direction in FIG. 7) of the n-type GaN substrate. ) Was confirmed to be formed in a stripe shape along the line.

  Next, a semiconductor layer made of GaN was epitaxially grown on the underlayer using MOCVD. As a result, as shown in FIG. 14, while forming the (000-1) plane of GaN extending in the vertical direction so that the semiconductor layer takes over this plane orientation on the inner side surface composed of the (000-1) plane of the crack. Crystal growth was confirmed in the [1-100] (C2 direction) direction. Further, as shown in FIG. 14, it was confirmed that a facet composed of the (1-101) plane of GaN was formed on the inner surface opposite to the (000-1) plane of the crack. Further, it was confirmed that the inclined surface is formed so as to form an obtuse angle with respect to the upper surface (main surface) of the semiconductor layer. Thereby, it was confirmed that the two inner surfaces of the cracks provided in the underlayer were the starting points of crystal growth, respectively, and it was possible to form a semiconductor layer on the underlayer. Further, it was confirmed that the crack that had reached the n-type GaN substrate at the time of forming the underlayer was filled in part of the gap with the lamination of the semiconductor layers.

  From the results of the above confirmation experiment, in the method for forming a nitride-based semiconductor element layer according to the present invention, the semiconductor layer (light emitting layer) (000) is formed without using an etching process or a cleavage step simultaneously with the formation of the semiconductor layer by crystal growth. It was confirmed that it was possible to form a resonator end surface (light emitting surface side) composed of a -1) surface and an end surface composed of a (1-101) surface (an inclined surface of a semiconductor layer). Further, in the process of crystal growth of the semiconductor layer, the upper surface (main surface) of the semiconductor layer is in the direction indicated by arrow C2 (see FIG. 5) than the growth rate of the portion where the (000-1) plane and (1-101) plane are formed. 13), the growth rate is high, so that not only the flatness of the (000-1) plane and the (1-101) plane but also the flatness of the upper surface (main surface) of the semiconductor layer can be improved. It was confirmed that it was possible.

(Third embodiment)
FIG. 15 is a sectional view showing the structure of a surface-emitting nitride-based semiconductor laser device according to the third embodiment of the present invention. Referring to FIG. 15, in the surface-emitting nitride semiconductor laser device 60 according to the third embodiment, unlike the first embodiment, an n-type having a main surface composed of a substantially (1-10-2) plane. A case where the semiconductor laser element layer 12 is formed after forming the base layer 40 made of AlGaN on the n-type GaN substrate 61 using the GaN substrate 61 will be described. The n-type GaN substrate 61 is an example of the “substrate” in the present invention.

  Here, in the third embodiment, the semiconductor laser element layer 12 is formed on the main surface made of the substantially (1-10-2) plane of the n-type GaN substrate 61 via the base layer 40. The semiconductor laser element layer 12 is formed with a light emitting surface 60a and a light reflecting surface 60b that are substantially perpendicular to the main surface of the n-type GaN substrate 61 in the resonator direction (A direction). The light emitting surface 60a and the light reflecting surface 60b are examples of the “first resonator end surface” and the “second resonator end surface” in the present invention, respectively.

In the third embodiment, the reflective surface 60c extending in a direction inclined by a predetermined angle θ ₅ (= about 47 °) with respect to the light emitting surface 60a in the region facing the light emitting surface 60a of the semiconductor laser element layer 12. Is formed. The reflection surface 60c is formed by a facet composed of a (000-1) plane accompanying crystal growth when the semiconductor laser element layer 12 is formed. Thereby, in the surface emitting nitride semiconductor laser device 60, as shown in FIG. 15, the laser light emitted in the A2 direction from the light emitting surface 60a of the light emitting layer 15 is separated from the light emitting surface 60a by the reflecting surface 60c. The emission direction can be changed in substantially the same direction ([1-10-2] direction (C2 direction)). Further, as shown in FIG. 15, an end face 60 d is formed at the end portion in the A2 direction of the surface emitting nitride semiconductor laser element 60.

  The remaining element structure of the surface emitting nitride semiconductor laser element 60 according to the third embodiment is the same as that of the first embodiment.

  16 and 17 are cross-sectional views for explaining the manufacturing process of the surface-emitting nitride semiconductor laser device according to the third embodiment shown in FIG. A manufacturing process for the surface-emitting nitride semiconductor laser device 60 according to the third embodiment is now described with reference to FIGS.

  Here, in the third embodiment, the base layer 40 is grown on the n-type GaN substrate 61 by the same manufacturing process as in the first embodiment. A crack 41 is formed in the underlayer 40 due to a difference in lattice constant between the n-type GaN substrate 61 and the underlayer 40. At this time, the difference in the c-axis lattice constant between GaN and AlGaN is larger than the difference in the a-axis lattice constant between GaN and AlGaN, so that the crack 41 has a (0001) plane and an n-type GaN substrate 61. It is formed to extend in a stripe shape along the [11-20] direction (B direction) parallel to the (1-10-2) plane of the main surface.

  Thereafter, as shown in FIG. 16, the semiconductor laser element layer 12 is formed on the underlayer 40 by the same manufacturing process as in the first embodiment.

Here, in the third embodiment, as shown in FIG. 16, when the semiconductor laser element layer 12 is grown on the underlayer 40, the inner surface 41 b of the crack 41 extending in a stripe shape in the [11-20] direction. The semiconductor laser element layer 12 forms a reflection surface 60c composed of a (000-1) plane extending in a direction inclined by an angle θ ₅ (= about 47 °) with respect to the [1-10-2] direction (C2 direction). While growing crystal.

In the third embodiment, on the inner surface 41 a side facing the inner surface 41 b of the crack 41, the semiconductor laser element layer 12 has an angle θ ₆ (= C1 direction) with respect to the [1-10-2] direction (C2 direction). The crystal grows while forming a crystal growth surface 60d composed of a (1-101) plane extending in an inclined direction (about 15 °). Therefore, the reflection surface 60c and the crystal growth surface 60d are formed so as to form an obtuse angle with respect to the upper surface (main surface) of the semiconductor laser element layer 12, respectively.

  Then, the current blocking layer 18 and the p-side electrode 19 are formed on the semiconductor laser element layer 12 by the same manufacturing process as in the first embodiment, as shown in FIG. Further, as shown in FIG. 17, after the back surface of the n-type GaN substrate 61 is polished, the n-side electrode 20 is formed on the back surface of the n-type GaN substrate 61 by using a vacuum evaporation method.

  Here, in the third embodiment, as shown in FIG. 17, on the crystal growth surface 60d (see FIG. 16) side, the direction from the surface side (upper surface side) of the semiconductor laser element layer 12 to the n-type GaN substrate 61 ( The groove 62 is formed by dry etching in the direction of arrow C1. As a result, a portion of the crystal growth surface 60d (see FIG. 16) of the semiconductor laser element layer 12 is removed, and a light emitting surface 60a that is an end surface substantially perpendicular to the main surface on the n-type GaN substrate 61 is formed. . In addition, as shown in FIG. 17, the crack 41 (refer FIG. 16) of the base layer 40 is also removed with formation of the groove part 62. As shown in FIG.

  In the third embodiment, as shown in FIG. 17, the position where the predetermined resonator end face is to be formed is the direction (arrow C1) from the surface side (upper surface side) of the semiconductor laser element layer 12 to the n-type GaN substrate 61. The groove 63 is formed by dry etching in the direction). Thereby, one side surface of the groove 63 is easily formed as the light reflecting surface 60 b of the surface emitting nitride semiconductor laser element 60. The other side surface of the groove 63 is formed as an end surface 60 d of the surface emitting nitride semiconductor laser element 60. In addition, the groove part 63 is formed so as to extend in the [11-20] direction (B direction) substantially parallel to the extending direction of the groove part 62 in a plan view.

  Then, as shown in FIG. 17, a scribe groove 64 is formed in the groove portion 63 in parallel with the groove portion 63 of the n-type GaN substrate 61 (perpendicular to the paper surface of FIG. 17) by laser scribe or mechanical scribe. In this state, the wafer is separated at the position of the scribe groove 64 as shown in FIG. In addition, as shown in FIG. 15, the groove part 63 of the n-type GaN substrate 61 becomes a step part 61a formed in the lower part of the light reflection surface 60b after the element division.

  Thereafter, the device is divided into chips along the resonator direction (A direction), whereby the surface emitting nitride semiconductor laser device 60 according to the third embodiment shown in FIG. 15 is formed.

In the third embodiment, as described above, the angle θ _{5 with} respect to the light emitting surface 60 a formed at the end of the semiconductor laser element layer 12 and the substantially (1-10-2) plane of the n-type GaN substrate 61. (= About 47 °) By providing the reflective surface 60c composed of the (000-1) plane extending in an inclined manner, the reflective surface 60c composed of the (000-1) plane is flat as in the first embodiment. Therefore, the laser beam emitted from the light emitting surface 60a can be emitted by changing the emitting direction uniformly without causing scattering on the reflecting surface 60c. As a result, it is possible to suppress a decrease in the light emission efficiency of the surface emitting nitride semiconductor laser element 60. The remaining effects of the third embodiment are similar to those of the aforementioned first and second embodiments.

(Modification of the third embodiment)
FIG. 18 is a cross-sectional view showing the structure of a surface emitting nitride-based semiconductor laser device according to a modification of the third embodiment of the present invention. FIG. 19 is a cross-sectional view for explaining the manufacturing process of the surface-emitting nitride-based semiconductor laser device according to the modification of the third embodiment shown in FIG. Referring to FIGS. 16, 18 and 19, in the surface emitting nitride semiconductor laser device 70 according to the modification of the third embodiment, unlike the third embodiment, in the manufacturing process, the semiconductor laser device layer The case where the semiconductor laser element layer 12 is etched so that the crystal growth surface 60d ((1-101) surface side) of the two facets at the time of forming 12 is used as the laser light reflecting surface 70c will be described.

Here, in the modification of the third embodiment, as shown in FIG. 18, an angle θ ₆ (= about 15 °) with respect to the light emitting surface 70 a is formed in a region facing the light emitting surface 70 a of the semiconductor laser element layer 12. ) An inclined reflecting surface 70c is formed. The reflective surface 70c is formed by a facet composed of a (1-101) plane. Thereby, in the surface emitting nitride semiconductor laser element 70, as shown in FIG. 18, the laser light emitted in the A1 direction from the light emitting surface 70a of the light emitting layer 15 is reflected on the light emitting surface 70a by the reflecting surface 70c. On the other hand, the emission direction can be changed in a direction inclined by an angle θ ₇ (= about 60 °). Further, as shown in FIG. 18, a light reflecting surface 70b and an end surface 70d are formed at both ends of the surface-emitting nitride semiconductor laser element 70, respectively. The light emitting surface 70a and the light reflecting surface 70b are examples of the “first resonator end surface” and the “second resonator end surface” in the present invention, respectively. The other element structure of the surface emitting nitride semiconductor laser element 70 according to the modification of the third embodiment is the same as that of the third embodiment.

  Moreover, in the manufacturing process in the modification of 3rd Embodiment, as shown in FIG. 19, in the reflective surface 60c (refer FIG. 16) side which consists of (000-1) surface in the said 3rd Embodiment, a semiconductor laser element layer The groove 72 is formed by performing dry etching in a direction (arrow C1 direction) reaching the n-type GaN substrate 61 from the surface side (upper surface side) of FIG. Thereby, the portion of the reflection surface 60c (see FIG. 16) is removed, and the light emission surface 70a that is an end surface substantially perpendicular to the main surface on the n-type GaN substrate 61 is easily formed. In addition, as shown in FIG. 19, the crack 41 (refer FIG. 16) of the foundation | substrate layer 40 is also removed with formation of the groove part 72. As shown in FIG.

  In the third embodiment, as shown in FIG. 19, the position where a predetermined resonator end face is to be formed is a direction (arrow C1) from the surface side (upper surface side) of the semiconductor laser element layer 12 to the n-type GaN substrate 61. The groove 73 is formed by dry etching in the direction). Thereby, one side surface of the groove 73 is formed as the light reflecting surface 70 b of the surface emitting nitride semiconductor laser element 70. The other side surface of the groove 73 is formed as an end surface 70 d of the surface emitting nitride semiconductor laser element 70.

  The other manufacturing processes of the surface emitting nitride semiconductor laser device 70 according to the modification of the third embodiment are the same as those of the third embodiment. The effect of the modification of the third embodiment is the same as that of the third embodiment.

(Fourth embodiment)
FIG. 20 is a cross-sectional view showing the structure of a surface-emitting nitride-based semiconductor laser device according to the fourth embodiment of the present invention. 21 and 22 are cross-sectional views for explaining the manufacturing process of the surface-emitting nitride semiconductor laser device according to the fourth embodiment shown in FIG. Referring to FIGS. 20 to 22, the surface emitting nitride semiconductor laser device 80 according to the fourth embodiment differs from the third embodiment in that the main surface composed of a substantially (11-2-3) plane is formed. A case where the semiconductor laser element layer 12 is formed on the main surface of the n-type GaN substrate 81 using the n-type GaN substrate 81 that is included will be described.

Here, in the fourth embodiment, as shown in FIG. 20, the region facing the light emitting surface 80 a of the semiconductor laser element layer 12 is inclined by an angle θ ₈ (= about 43 °) with respect to the light emitting surface 80 a. A reflective surface 80c is formed. The reflecting surface 80c is formed by a facet composed of a (000-1) plane. Thereby, in the surface emitting nitride semiconductor laser element 80, as shown in FIG. 20, the laser light emitted in the A2 direction from the light emitting surface 80a of the light emitting layer 15 is separated from the light emitting surface 80a by the reflecting surface 80c. The emission direction can be changed in substantially the same direction ([11-2-3] direction (C2 direction)). Further, as shown in FIG. 20, a light reflecting surface 80b and an end surface 80d are formed at both ends of the surface emitting nitride semiconductor laser element 80, respectively. The light emitting surface 80a and the light reflecting surface 80b are examples of the “first resonator end surface” and the “second resonator end surface” in the present invention, respectively. The other element structure of the surface emitting nitride semiconductor laser element 80 according to the fourth embodiment is the same as that of the third embodiment.

In the manufacturing process of the fourth embodiment, as in the third embodiment, as shown in FIG. 21, when the semiconductor laser element layer 12 is grown on the base layer 40, the [11-20] direction is formed. On the inner side surface 41b of the crack 41 extending in a stripe shape, the semiconductor laser element layer 12 extends in a direction inclined by an angle θ ₈ (= about 43 °) with respect to the [11-2-3] direction (C2 direction) (000). -1) Crystals grow while forming a reflecting surface 80c composed of a plane. On the inner surface 41a side of the crack 41, the semiconductor laser element layer 12 extends in a direction inclined by an angle θ ₉ (= about 16 °) with respect to the [11-2-3] direction (C2 direction) (11−). 22) The crystal grows while forming a crystal growth surface 80d composed of a plane. Therefore, the reflecting surface 80c and the crystal growth surface 80d are formed so as to form an obtuse angle with respect to the upper surface (main surface) of the semiconductor laser element layer 12, respectively.

  After that, as shown in FIG. 22, on the crystal growth surface 80d side, dry etching is performed in a direction (arrow C1 direction) reaching the n-type GaN substrate 81 from the surface side (upper surface side) of the semiconductor laser element layer 12 to thereby form the groove portion. 82 is formed. Thereby, the portion of the crystal growth surface 80d (see FIG. 21) of the semiconductor laser element layer 12 is removed, and the light emitting surface 80a that is an end surface substantially perpendicular to the main surface on the n-type GaN substrate 81 is easily formed. Is done. In addition, as shown in FIG. 22, the crack 41 (refer FIG. 21) of the base layer 40 is also removed with formation of the groove part 82. FIG.

  In the fourth embodiment, the groove 83 is formed by the same manufacturing process as in the third embodiment. Thus, one side surface of the groove 83 is formed as the light reflecting surface 80 b of the surface emitting nitride semiconductor laser element 80. The other side surface of the groove 83 is formed as an end surface 80 d of the surface emitting nitride semiconductor laser element 80.

  The other manufacturing processes of the surface emitting nitride semiconductor laser element 80 according to the fourth embodiment are the same as those of the third embodiment. The effects of the fourth embodiment are the same as those of the third embodiment.

(Fifth embodiment)
FIG. 23 is a cross-sectional view showing a structure in which a surface-emitting nitride-based semiconductor laser device according to a fifth embodiment of the present invention and a monitor built-in submount are combined. With reference to FIG. 23, a structure in which a surface-emitting nitride-based semiconductor laser device 100 according to a fifth embodiment and a monitoring photodiode (PD) built-in submount 110 are combined will be described.

  In the fifth embodiment, as shown in FIG. 23, a surface-emitting nitride-based semiconductor laser device 100 having a structure similar to that of the surface-emitting nitride-based semiconductor laser device 80 shown in the fourth embodiment includes: It is fixed to the monitor built-in submount 110 made of Si. In addition, a recess 110a is formed in a substantially central portion of the monitor built-in submount 110, and a PD 111 is incorporated in the inner bottom surface of the recess 110a. The PD 111 is an example of the “light sensor” in the present invention.

  Here, in the fifth embodiment, the main surface 110b of the monitor PD built-in submount 110 is formed substantially parallel to the back surface 110c. The surface-emitting nitride semiconductor laser device 100 is fixed on the main surface 110b so as to straddle the recess 110a opened on the main surface 110b side of the monitoring PD built-in submount 110 in the A direction.

  In the fifth embodiment, the surface emitting nitride semiconductor laser element 100 is an end face light emitting laser element, and as shown in FIG. 23, the laser light emitted from the light emitting layer 15 is the end face 100a (light The emission intensity of the laser beam 101a (solid line) emitted from the emission surface) is configured to be greater than the emission intensity of the laser beam 101b (dashed line) emitted from the end surface 100b (light reflection surface). . The end face 100a and the end face 100b are examples of the “second resonator end face” and the “first resonator end face” in the present invention, respectively.

Therefore, in the monitor built-in PD submount 110, as shown in FIG. 23, the laser light 101b emitted from the end face 100b of the surface emitting nitride semiconductor laser element 100 to the reflecting surface 100c is (000-1). It is configured to be incident on the PD 111 provided on the monitoring PD built-in submount 110 by the reflecting surface 100c. At this time, since the reflecting surface 100c is inclined at an angle θ ₈ (= about 43 °) with respect to the main surface of the n-type GaN substrate 81, the laser light 101b is incident substantially perpendicularly to the PD 111. The

  In the fifth embodiment, as described above, the laser light 101b emitted from the end face 100b made of the (000-1) plane of the light emitting layer 15 of the surface emitting nitride semiconductor laser element 100 is converted into the semiconductor laser element layer 12. The reflective surface 100c made of the (000-1) plane, which is the growth surface at the time of crystal growth, is configured to change the emission direction in a direction intersecting with the emission direction from the light emitting layer 15, and surface emitting nitride By combining the semiconductor laser element 100 and the monitor built-in PD submount 110, the laser beam 101b is configured to enter the PD 111 of the monitor PD built-in submount 110 substantially perpendicularly. As a result, the laser light 101b (sample light for monitoring the laser light intensity of the edge-emitting laser element) in which light scattering is suppressed by the reflecting surface 100c having good flatness as the crystal growth surface can be guided to the PD 111. Therefore, the laser beam intensity can be measured more accurately. The remaining effects of the fifth embodiment are similar to those of the aforementioned fourth embodiment.

(Sixth embodiment)
FIG. 24 is a perspective view showing the structure of a surface emitting laser array according to the sixth embodiment of the present invention. The structure of the surface emitting laser array 120 according to the sixth embodiment will be described with reference to FIGS.

  As shown in FIG. 24, the surface emitting laser array 120 according to the sixth embodiment includes the surface emitting nitride semiconductor laser device 80 (see FIG. 20) according to the fourth embodiment in the vertical and horizontal directions on the wafer. Each is formed by arranging three (9 in total) in a two-dimensional array.

  Here, in the sixth embodiment, as shown in FIG. 24, after the semiconductor laser element layer 12 is formed on the n-type GaN substrate 81 by the same manufacturing process as in the fourth embodiment, the resonator is formed by etching technique. A separation groove 121 is formed for separating the semiconductor laser element layers 12 of the surface-emitting nitride-based semiconductor laser element 80 adjacent in the direction (A direction) in the A direction. By forming the separation groove 121, the light reflecting surface 80 b of the resonator end face of each surface emitting nitride semiconductor laser element 80 is formed in the semiconductor laser element layer 12.

  In the sixth embodiment, as shown in FIG. 24, nine laser beams emitted from the light emitting surface 80a of each surface emitting type nitride semiconductor laser element 80 of the surface emitting laser array 120 are (000− 1) It is possible to emit upward by changing the emitting direction in the substantially same direction ([11-2-3] direction (C2 direction)) with respect to the light emitting surface 80a by the reflecting surface 80c formed of a surface. It is configured. As shown in FIG. 24, an end face 80d of the semiconductor laser element layer 12 is formed at the end portion in the A2 direction of the semiconductor laser element layer 12 by dry etching in the manufacturing process. In FIG. 24, in order to clearly show the reflection of the laser beam by the reflecting surface 80c, a part of the semiconductor laser element layer 12 (p-type contact layer 17 and current blocking layer 18) formed on the reflecting surface 80c side. The p-side electrode 19 is not shown.

  In the sixth embodiment, as described above, the surface emitting laser array 120 is used to transmit nine laser beams emitted from the light emitting surface 80a of each surface emitting nitride semiconductor laser element 80 to the semiconductor laser element layer 12. The light is reflected by the reflecting surface 80c composed of the (000-1) plane which is a growth surface at the time of crystal growth and is emitted while changing the emitting direction in a direction substantially perpendicular to the main surface of the n-type GaN substrate 81. Therefore, it is used as a light source for a surface emitting laser. As a result, a plurality of laser beams (nine beams) whose light scattering is suppressed are emitted by a plurality of reflecting surfaces 80c (nine locations) having good flatness as crystal growth surfaces, so that the light emission efficiency is improved. A surface emitting laser can be formed.

(Seventh embodiment)
FIG. 25 is a perspective view showing the structure of a nitride-based semiconductor laser device according to the seventh embodiment of the present invention. FIG. 26 is a cross-sectional view showing the structure of the nitride-based semiconductor laser device shown in FIG. Referring to FIGS. 25 and 26, in nitride-based semiconductor laser device 140 according to the seventh embodiment, unlike the first embodiment, an n-type having a main surface made of a substantially (1-10-4) plane. A case will be described in which the semiconductor laser element layer 12 is formed after a recess (groove 150 to be described later) extending in the [11-20] direction (direction perpendicular to the paper surface of FIG. 26) is formed on the GaN substrate 141. The n-type GaN substrate 141 and the groove 150 are examples of the “substrate” and the “concave portion” of the present invention, respectively.

  In the nitride-based semiconductor laser device 140 according to the seventh embodiment, as shown in FIG. 25, a stepped portion 141a is formed at the end in the resonator direction (A direction). A semiconductor laser element layer 12 having a thickness of about 3.1 μm is formed on an n-type GaN substrate 141 having a thickness of about 100 μm. In addition, as shown in FIG. 26, the semiconductor laser element layer 12 has a length L1 between laser element end portions (A direction) of about 1560 μm, and n-type semiconductor laser element layers 140 at both ends of the nitride semiconductor laser element 140. A light emitting surface 140a and a light reflecting surface 140b that are substantially perpendicular to the main surface of the GaN substrate 141 are formed. The light emitting surface 140a and the light reflecting surface 140b are examples of the “first resonator end surface” and the “second resonator end surface” of the present invention, respectively.

  Here, in the seventh embodiment, the semiconductor laser element layer 12 is formed on the main surface made of the substantially (1-10-4) plane of the n-type GaN substrate 141. Further, the stepped portion 141 a formed at the lower part of the n-type GaN substrate 141 on the light emitting surface 140 a side has an end surface 141 b composed of a (1-101) plane substantially perpendicular to the main surface of the n-type GaN substrate 141. Yes. As shown in FIG. 25, the light emitting surface 140a of the semiconductor laser element layer 12 is formed by a substantially (1-101) plane on which crystal growth has taken place over the end face 141b of the n-type GaN substrate 141. The light reflecting surface 140b of the semiconductor laser element layer 12 is formed by a (−110-1) plane that is an end surface perpendicular to the [−110-1] direction (A1 direction in FIG. 26).

  The element structure of the semiconductor laser element layer 12 of the nitride semiconductor laser element 140 according to the seventh embodiment is the same as that of the first embodiment.

  27 to 29 are cross-sectional views for explaining the manufacturing process of the nitride-based semiconductor laser device according to the seventh embodiment shown in FIG. A manufacturing process for the nitride-based semiconductor laser device 140 according to the seventh embodiment is now described with reference to FIGS.

  First, as shown in FIG. 27, an etching technique is used to form approximately 40 μm in the [1-101] direction (A direction) on the main surface composed of the substantially (1-10-4) plane of the n-type GaN substrate 141. A groove 150 having a width W1 and a depth of about 2 μm and extending in the [11-20] direction (B direction) is formed. Then, the semiconductor laser element layer 12 is grown on the n-type GaN substrate 141 using MOCVD.

  Here, in the seventh embodiment, as shown in FIG. 28, the semiconductor laser element layer 12 takes over the (1-101) surface of the groove 150 on the inner side surface 150 a made of the (1-101) surface of the groove 150. Thus, the crystal grows while forming the (1-101) plane extending in the [1-10-4] direction (C2 direction). Thereby, the (1-101) plane of the semiconductor laser element layer 12 is formed as the light emitting surface 140 a of the nitride-based semiconductor laser element 140.

In the seventh embodiment, on the (−110-1) plane (inner surface 150b) side facing the (1-101) plane of the groove 150, the semiconductor laser element layer 12 is in the [1-10-4] direction. The crystal grows while forming a crystal growth surface 140c composed of a (000-1) plane extending in a direction inclined by an angle θ ₁₀ (= about 65 °) with respect to (C2 direction). Therefore, the crystal growth surface 140c is formed so as to form an obtuse angle with respect to the upper surface (main surface) of the semiconductor laser element layer 12. The inner side surface 150a and the inner side surface 150b are examples of the “inner side surface of the recess” in the present invention.

  Thereafter, as shown in FIG. 29, the current blocking layer 18 (see FIG. 25) and the p-side electrode 19 are formed on the semiconductor laser element layer 12 by the same manufacturing process as in the first embodiment. 29, after polishing the back surface of the n-type GaN substrate 141, the n-side electrode 20 is formed on the back surface of the n-type GaN substrate 141 using a vacuum deposition method.

  In the manufacturing process of the seventh embodiment, as shown in FIG. 29, the position where the predetermined resonator end face is to be formed extends from the surface side (upper surface side) of the semiconductor laser element layer 12 to the n-type GaN substrate 141. By performing dry etching in the direction of arrow C1, a groove 151 having a substantially (−110-1) plane on one side surface of the semiconductor laser element layer 12 is formed. As a result, the substantially (−110-1) surface, which is one side surface of the groove 151, is easily formed as the light reflecting surface 140 b of the nitride-based semiconductor laser device 140. The groove 151 is formed so as to extend in the [11-20] direction (the B direction in FIG. 29) substantially parallel to the direction in which the groove 150 extends in plan view.

  Then, as shown in FIG. 29, scribe grooves 152 are formed in the grooves 150 and 151 in parallel with the grooves 150 by laser scribe or mechanical scribe. In this state, as shown in FIG. 29, separation is performed at the position of the scribe groove 152. As shown in FIG. 25, the groove 150 of the n-type GaN substrate 141 becomes a stepped portion 141a formed in the lower part of the light emitting surface 140a after the element is divided.

  Thereafter, the device is divided into chips along the resonator direction (A direction in FIG. 26), thereby forming the nitride-based semiconductor laser device 140 according to the seventh embodiment shown in FIG.

  In the seventh embodiment, as described above, by providing the light emitting surface 140a formed of a substantially (1-101) plane substantially perpendicular to the main surface of the n-type GaN substrate 141, the semiconductor laser device is manufactured in terms of the manufacturing process. At the same time as the crystal growth of the layer 12, the light emitting surface 140 a composed of the (1-101) plane is formed so as to take over the inner surface 150 a composed of the (1-101) plane of the groove 150 formed in the n-type GaN substrate 141. be able to. Thereby, even when the (1-101) plane having no cleavage property is used as the resonator plane, the light emitting surface 140a can be formed without using an etching process. Further, by forming the light emitting surface 140a composed of the (1-101) plane by crystal growth, the growth is made in comparison with the growth layer surface of the nitride-based semiconductor element layer when the (1-101) end face is not formed. The flatness of the layer surface (main surface) can be improved. The remaining effects of the seventh embodiment are similar to those of the aforementioned first embodiment.

(Eighth embodiment)
FIG. 30 is a sectional view showing the structure of a nitride-based semiconductor laser device according to the eighth embodiment of the present invention. Referring to FIG. 30, in the nitride-based semiconductor laser device 160 according to the eighth embodiment, unlike the first embodiment, an n-type GaN substrate 161 having a main surface substantially consisting of (11-2-5) plane. The case where the semiconductor laser element layer 12 is formed after the underlayer 40 made of AlGaN is formed thereon will be described. The n-type GaN substrate 161 is an example of the “substrate” in the present invention.

  Here, in the eighth embodiment, the semiconductor laser element layer 12 is formed on the main surface made of the substantially (1-10-2) plane of the n-type GaN substrate 161 with the underlayer 40 interposed therebetween. The light emitting surface 160a of the semiconductor laser element layer 12 is formed by a crystal growth surface composed of a (11-22) plane on which crystal growth has taken place so as to take over the inner side surface 41a of the crack 41 of the underlayer 40. The light reflecting surface 160b of the semiconductor laser element layer 12 is formed by a (-1-12-2) plane that is an end surface perpendicular to the [11-22] direction (A2 direction in FIG. 30). The light emitting surface 160a and the light reflecting surface 160b are examples of the “first resonator end surface” and the “second resonator end surface” in the present invention, respectively. A stepped portion 160d is formed below the light reflecting surface 160b.

  The element structure of the semiconductor laser element layer 12 of the nitride-based semiconductor laser element 160 according to the eighth embodiment is the same as that of the first embodiment.

  FIG. 31 is a cross-sectional view for explaining a manufacturing process for the nitride-based semiconductor laser device according to the eighth embodiment shown in FIG. A manufacturing process for the nitride-based semiconductor laser device 160 according to the eighth embodiment is now described with reference to FIGS.

  In the eighth embodiment, the foundation layer 40 is grown on the n-type GaN substrate 161 by the same manufacturing process as in the first embodiment. A crack 41 is formed in the underlayer 40 due to the difference in lattice constant between the n-type GaN substrate 161 and the underlayer 40. The cracks 41 are formed in a stripe shape along the [1-100] direction (direction perpendicular to the paper surface of FIG. 31).

  Thereafter, as shown in FIG. 31, the semiconductor laser element layer 12 is formed on the underlayer 40 by the same manufacturing process as in the first embodiment.

  Here, in the eighth embodiment, as shown in FIG. 31, when the semiconductor laser element layer 12 is grown on the underlayer 40, the inner surface 41a of the crack 41 extending in a stripe shape in the [1-100] direction. The semiconductor laser element layer 12 grows while forming a (11-22) plane extending in the [11-2-5] direction (C2 direction). Thereby, the (11-22) plane of the semiconductor laser element layer 12 is formed as the light emitting surface 160 a of the nitride-based semiconductor laser element 160.

In the eighth embodiment, the semiconductor laser element layer 12 is inclined at an angle θ ₁₁ (= about 57 °) with respect to the [11-2-5] direction (C2 direction) on the inner surface 41b side of the crack 41. The crystal grows while forming a crystal growth surface 160c composed of a (000-1) plane extending in the direction.

  Then, as shown in FIG. 31, the current blocking layer 18 (see FIG. 3) and the p-side electrode 19 are formed on the semiconductor laser element layer 12. Further, as shown in FIG. 31, after the back surface of the n-type GaN substrate 161 is polished, the n-side electrode 20 is formed on the back surface of the n-type GaN substrate 161 by using a vacuum evaporation method.

  In the eighth embodiment, as shown in FIG. 31, the position where a predetermined resonator end face is to be formed extends from the surface side (upper surface side) of the semiconductor laser element layer 12 to the n-type GaN substrate 161 (arrow C1). By performing dry etching in the direction), a groove 162 having a substantially (-1-12-2) plane on one side of the semiconductor laser element layer 12 is formed. As a result, the substantially (−1-12-2) surface, which is one side surface of the groove 162, is easily formed as the light reflecting surface 160 b of the nitride-based semiconductor laser device 160. The groove 162 is formed so as to extend in the [1-100] direction (B direction) substantially parallel to the direction in which the crack 41 extends in plan view.

  Then, as shown in FIG. 31, a scribe groove 163 is formed in the crack 41 and the groove portion 162 in parallel with the groove portion 162 by laser scribe or mechanical scribe. In this state, the wafer is separated at the position of the scribe groove 163 as shown in FIG. In addition, the groove part 162 of the n-type GaN substrate 161 becomes a step part 160d formed in the lower part of the light reflecting surface 160b after the element division, as shown in FIG.

  Thereafter, the device is divided into chips along the resonator direction (A direction in FIG. 30), whereby the nitride-based semiconductor laser device 160 according to the eighth embodiment shown in FIG. 30 is formed.

  In the eighth embodiment, as described above, by providing the light emitting surface 160a formed of a substantially (11-22) plane substantially perpendicular to the main surface of the n-type GaN substrate 161, the semiconductor laser device is manufactured in terms of the manufacturing process. The light emitting surface 160a composed of the (11-22) plane can be formed so as to take over the inner side surface 41a of the crack 41 formed in the n-type GaN substrate 161 simultaneously with the crystal growth of the layer 12. Thereby, even when the (11-22) surface having no cleavage property is used as the resonator surface, the light emitting surface 160a can be formed without using an etching process. Further, the flatness of the growth layer surface (main surface) can be improved by forming the light emitting surface 160a having the (11-22) plane by crystal growth. The remaining effects of the eighth embodiment are similar to those of the aforementioned seventh embodiment.

(Modification of the eighth embodiment)
32 and 33 are plan views for explaining the manufacturing process for the nitride-based semiconductor laser device according to the modification of the eighth embodiment of the present invention. With reference to FIGS. 6 and 30 to 33, in the manufacturing process according to the modification of the eighth embodiment, unlike the above-described eighth embodiment, a broken-line scribe scratch is formed on the underlayer 40 on the n-type GaN substrate 161. The case where the crack 181 in which the crack generation position is controlled by forming 180 will be described. The crack 181 is an example of the “concave portion” in the present invention.

  Here, in the modification of the eighth embodiment, as shown in FIG. 32, the thickness is thinner than the thickness (about 3 μm to about 4 μm) of the above-described eighth embodiment on the n-type GaN substrate 161 (see FIG. 31). An underlayer 40 having a thickness about the critical thickness is grown. At this time, a tensile stress R (see FIG. 6) is generated in the underlayer 40 by the same action as in the eighth embodiment. Here, the critical film thickness means the minimum thickness of the semiconductor layer when a semiconductor layer having a different lattice constant is stacked and no cracks are generated in the semiconductor layer due to the difference in lattice constant.

  Thereafter, as shown in FIG. 32, scribe flaws 180 having a broken line shape (about 40 μm intervals) extending in the B direction are formed in the base layer 40 by laser light or diamond points at intervals L2 (= about 1600 μm) in the A direction. Form. As a result, as shown in FIG. 33, the crack progresses in the base layer 40 in the region of the base layer 40 where the scribe scratch 180 is not formed, starting from the broken scribe scratch 180. As a result, a substantially linear crack 181 that divides the base layer 40 in the B direction is formed.

  At that time, the scribe scratch 180 is also divided in the depth direction (direction perpendicular to the paper surface of FIG. 32). As a result, an inner side surface 181 a (shown by a broken line in FIG. 33) reaching the vicinity of the interface between the foundation layer 40 and the n-type GaN substrate 161 is formed in the crack 181. The inner side surface 181a is formed substantially perpendicular to the main surface composed of the (11-2-5) plane of the n-type GaN substrate 161. The inner side surface 181a is an example of the “inner side surface of the recess” in the present invention.

  Similarly to the eighth embodiment, on the side of the inner surface 181b (see FIG. 33) facing the inner surface 181a of the crack 181, the semiconductor laser element layer 12 is predetermined in the [11-2-5] direction. The crystal grows while forming a crystal growth surface 160c (see FIG. 31) composed of a (000-1) plane extending in a direction inclined at an angle of about 57 °. The inner side surface 181b is an example of the “inner side surface of the recess” in the present invention. The remaining element structure and manufacturing process of the nitride-based semiconductor laser element 160 (see FIG. 31) in the modification of the eighth embodiment are the same as those in the eighth embodiment.

  In the manufacturing process according to the modification of the eighth embodiment, as described above, the base layer 40 is formed on the n-type GaN substrate 161 to have a thickness about the critical film thickness when the crack 181 is formed, and then the base layer 40 is formed. On the other hand, by forming the scribe scratches 180 in the direction of the broken line (interval of about 40 μm) in the B direction at equal intervals in the direction of the resonator (direction A), the underlayer 40 starts from the scribe scratches 180 in the form of the broken line. Cracks 181 are formed in parallel to the B direction and at equal intervals in the resonator direction (A direction). That is, as in the eighth embodiment, a nitride-based semiconductor in which the resonator lengths are more easily compared with the case where the semiconductor layer is stacked using the inner surface of the spontaneously formed crack. A laser element 160 (see FIG. 16) can be formed. The remaining effects of the modification of the eighth embodiment are similar to those of the aforementioned eighth embodiment.

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

  For example, in the nitride semiconductor laser elements according to the first to eighth embodiments, an example in which the semiconductor laser element layer 12 is formed of a nitride semiconductor element layer such as AlGaN or InGaN has been described. However, the semiconductor laser element layer may be formed of a Wurtzite nitride-based semiconductor element layer made of AlN, InN, BN, TlN, or a mixed crystal thereof.

  In the surface-emitting nitride semiconductor laser device according to the second embodiment, an example in which the semiconductor laser device layer 12 is formed on the main surface composed of the m-plane ((1-100) plane) of the n-type GaN substrate. The present invention is not limited to this. For example, when the semiconductor laser element layer is formed on a surface perpendicular to the (000 ± 1) plane of the n-type GaN substrate such as the a-plane ((11-20) plane). The main surface may be used.

  Further, in the surface emitting nitride semiconductor laser elements according to the first to third embodiments, an example in which cracks are spontaneously formed in the underlayer using the lattice constant difference between the n-type GaN substrate and the underlayer. However, the present invention is not limited to this, and the generation position is controlled by forming broken-line-shaped scribe flaws in the underlayer on the n-type GaN substrate, as in the modification of the eighth embodiment. A crack may be formed.

In the nitride-based semiconductor laser devices according to the first to eighth embodiments, the example in which the GaN substrate is used as the substrate has been shown. However, the present invention is not limited to this. For example, the a-plane ((11-20) R-plane ((1-102) plane) sapphire substrate, nitride-based semiconductor whose main surface is the main surface, a-plane ((11-20) plane) or m-plane ((1-100) plane) An a-plane SiC substrate or m-plane SiC substrate on which a nitride-based semiconductor whose main surface is grown in advance may be used. It may also be used such as LiAlO ₂ · LiGaO ₂ substrate a non-polar nitride-based semiconductor were previously grown above.

  In the nitride semiconductor laser elements according to the first to fifth embodiments and the eighth embodiment, an n-type GaN substrate is used as the substrate (underlying substrate), and an underlayer made of AlGaN is formed on the n-type GaN substrate. Although an example of the formation is shown, the present invention is not limited to this, and an InGaN substrate may be used as the substrate, and a base layer made of GaN or AlGaN may be formed on the InGaN substrate.

  Further, in the surface emitting nitride semiconductor laser elements according to the first to third embodiments, an example in which cracks are spontaneously formed in the underlayer using the lattice constant difference between the n-type GaN substrate and the underlayer. Although the present invention is not limited to this, the present invention is not limited to this. Only scribe scratches may be formed. Even if comprised in this way, the crack extended in a B direction can be introduce | transduced from the scribe flaw of both ends.

  In the surface-emitting nitride semiconductor laser device according to the fourth embodiment, the (000-1) plane side of the two facets formed when forming the semiconductor laser device layer 12 is the reflective surface (reflecting surface 80c). However, the present invention is not limited to this, and the facet composed of the (11-22) plane of the semiconductor laser element layer 12 is used as a reflective surface as in the modification of the third embodiment. An emission type nitride semiconductor laser element may be formed.

  In the nitride-based semiconductor laser device according to the seventh embodiment, the (1-101) end surface of the semiconductor laser device layer 12 is a light emitting surface 140a, and the (-110-1) end surface is a light reflecting surface 140b. However, the present invention is not limited to this, and the (−110-1) end surface may be a light emitting surface and the (1-101) end surface may be a light reflecting surface.

  In the nitride-based semiconductor laser device according to the eighth embodiment, the (11-22) end surface of the semiconductor laser device layer 12 is used as the light emitting surface 160a, and the (-1-12-2) end surface is used as the light reflecting surface. Although an example of 160b is shown, the present invention is not limited to this, and the (1-12-2) end face may be a light emitting face and the (11-22) end face may be a light reflecting face.

  In the nitride-based semiconductor laser device according to the modification of the eighth embodiment, an example in which the scribe flaws 180 for introducing cracks are formed in a broken line shape (at intervals of about 40 μm) in the underlayer 40 is shown. Not limited to this, scribe scratches may be formed at both end portions of the base layer 40 in the B direction (see FIG. 32) (regions corresponding to the end portions of the n-type GaN substrate 161). Even if comprised in this way, the crack extended in a B direction can be introduce | transduced from the scribe flaw of both ends.

In the nitride semiconductor laser elements according to the first to eighth embodiments, a lower clad layer, a light emitting layer (active layer), an upper clad layer, and the like are sequentially formed on a flat substrate, and the current thereon Although an example of forming a nitride-based semiconductor laser device having a gain-guided oxide stripe structure in which the path is narrowly limited by the current blocking layer has been shown, the present invention is not limited thereto, and the ridge portion is formed of SiO ₂ or AlGaN. A nitride-based semiconductor laser element having a refractive index guided ridge waveguide structure embedded with a current blocking layer made of, for example, may be formed.

It is sectional drawing for demonstrating the schematic structure of the semiconductor laser element by this invention. It is the figure which showed the range of the normal direction of the main surface of the board | substrate in the case of forming a semiconductor laser element using the crystal orientation of a nitride-type semiconductor, and the manufacturing process in this invention. 1 is a perspective view showing a structure of a surface emitting nitride-based semiconductor laser device according to a first embodiment of the present invention. FIG. FIG. 4 is a cross-sectional view for explaining the structure of the surface emitting nitride semiconductor laser element shown in FIG. 3. FIG. 4 is a cross-sectional view for explaining the structure of the surface emitting nitride semiconductor laser element shown in FIG. 3. FIG. 4 is a cross-sectional view for explaining a manufacturing process of the surface emitting nitride-based semiconductor laser device according to the first embodiment shown in FIG. 3. FIG. 5 is a plan view for explaining the manufacturing process of the surface-emitting nitride-based semiconductor laser device according to the first embodiment shown in FIG. 3. FIG. 4 is a cross-sectional view for explaining a manufacturing process of the surface emitting nitride-based semiconductor laser device according to the first embodiment shown in FIG. 3. FIG. 4 is a cross-sectional view for explaining a manufacturing process of the surface emitting nitride-based semiconductor laser device according to the first embodiment shown in FIG. 3. FIG. 4 is a cross-sectional view and a plan view for explaining a manufacturing process of the surface emitting nitride-based semiconductor laser device according to the first embodiment shown in FIG. 3. It is sectional drawing which showed the structure of the surface emitting nitride semiconductor laser element by 2nd Embodiment of this invention. FIG. 12 is a cross-sectional view for explaining a manufacturing process of the surface-emitting nitride-based semiconductor laser device according to the second embodiment shown in FIG. FIG. 12 is a photomicrograph of a state of crystal growth of a semiconductor layer on an n-type GaN substrate in the manufacturing process of the second embodiment shown in FIG. 11 observed using a scanning electron microscope. FIG. 12 is a photomicrograph of a state of crystal growth of a semiconductor layer on an n-type GaN substrate in the manufacturing process of the second embodiment shown in FIG. 11 observed using a scanning electron microscope. It is sectional drawing which showed the structure of the surface emitting nitride semiconductor laser element by 3rd Embodiment of this invention. FIG. 16 is a cross-sectional view for explaining a manufacturing process of the surface emitting nitride-based semiconductor laser device according to the third embodiment shown in FIG. 15. FIG. 16 is a cross-sectional view for explaining a manufacturing process of the surface emitting nitride-based semiconductor laser device according to the third embodiment shown in FIG. 15. It is sectional drawing which showed the structure of the surface-emitting nitride semiconductor laser element by the modification of 3rd Embodiment of this invention. FIG. 19 is a cross-sectional view for explaining a manufacturing process for the surface emitting nitride-based semiconductor laser device according to the modification of the third embodiment shown in FIG. 18. It is sectional drawing which showed the structure of the surface emitting nitride semiconductor laser element by 4th Embodiment of this invention. FIG. 21 is a cross-sectional view for explaining the manufacturing process of the surface emitting nitride-based semiconductor laser device according to the fourth embodiment shown in FIG. 20. FIG. 21 is a cross-sectional view for explaining the manufacturing process of the surface emitting nitride-based semiconductor laser device according to the fourth embodiment shown in FIG. 20. It is sectional drawing which showed the structure which combined the surface emitting nitride semiconductor laser element by 5th Embodiment of this invention, and sub PD built-in monitor PD. It is the perspective view which showed the structure of the surface emitting laser array by 6th Embodiment of this invention. It is the perspective view which showed the structure of the nitride type semiconductor laser element by 7th Embodiment of this invention. FIG. 26 is a cross-sectional view showing the structure of the nitride-based semiconductor laser device shown in FIG. 25. FIG. 26 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the seventh embodiment shown in FIG. 25. FIG. 26 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the seventh embodiment shown in FIG. 25. FIG. 26 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the seventh embodiment shown in FIG. 25. It is sectional drawing which showed the structure of the nitride type semiconductor laser element by 8th Embodiment of this invention. FIG. 31 is a cross-sectional view for explaining a manufacturing process for the nitride-based semiconductor laser device according to the eighth embodiment shown in FIG. 30. It is a top view for demonstrating the manufacturing process of the nitride type semiconductor laser element by the modification of 8th Embodiment of this invention. It is a top view for demonstrating the manufacturing process of the nitride type semiconductor laser element by the modification of 8th Embodiment of this invention.

Explanation of symbols

1 First semiconductor (substrate, nitride-based semiconductor element layer)
2 Active layer (light emitting layer, nitride-based semiconductor element layer)
3 Second semiconductor (nitride-based semiconductor element layer)
11, 51, 61, 81, 141, 161 n-type GaN substrate (substrate)
12 Semiconductor laser device layer (nitride-based semiconductor device layer)
13 Buffer layer (nitride semiconductor element layer)
14 n-type cladding layer (nitride semiconductor element layer)
15 Light emitting layer (nitride semiconductor element layer)
16 p-type cladding layer (nitride-based semiconductor element layer)
17 p-type contact layer (nitride semiconductor element layer)
30a, 50a, 60a, 70a, 80a, 140a, 160a Light exit surface (first resonator end surface)
30b, 50b, 60b, 70b, 80b, 140b, 160b Light reflecting surface (second resonator end surface)
30c, 50c, 60c, 70c, 80c, 100c Reflective surface 40 Underlayer 41, 181 Crack (recess)
41a, 150a, 181a Inner surface (inner surface of recess)
41b, 150b, 181b Inner surface (inner surface of recess)
100a End face (second resonator end face)
100b end face (first resonator end face)
101a Laser beam 150 Groove (recess)

Claims (8)

A nitride-based semiconductor element layer formed on the main surface of the substrate and having a light-emitting layer;
A first resonator end face formed at an end portion of the nitride-based semiconductor element layer including the light emitting layer;
A (000-1) plane, or a {A + B, A, -2A-B, 2A + B} plane, which is formed in a region facing the end face of the first resonator and extends at a predetermined angle with respect to at least the main surface A nitride-based semiconductor laser device comprising: a reflecting surface (where A ≧ 0 and B ≧ 0, and at least one of A and B is not 0). The substrate has a recess formed in the main surface;
The nitride-based semiconductor laser device according to claim 1, wherein the reflecting surface is formed of a crystal growth surface of the nitride-based semiconductor device layer formed from an inner side surface of the recess.   3. The nitride-based semiconductor according to claim 1, further comprising a second resonator end surface that is formed at an end opposite to the first resonator end surface and extends in a direction substantially perpendicular to the main surface. Laser element.   The nitride-based semiconductor laser device according to claim 1, wherein the substrate is made of a nitride-based semiconductor.   The laser beam emitted from the end face of the first resonator has its emission direction changed in a direction intersecting with the emission direction of the laser beam from the light emitting layer by the reflecting surface, and the laser beam monitoring light The nitride-based semiconductor laser device according to claim 1, wherein the nitride-based semiconductor laser device is configured to be incident on a sensor.   A surface emitting laser configured such that the laser beam emitted from the end face of the first resonator is changed in an emission direction by the reflecting surface in a direction intersecting with an emission direction of the laser beam from the light emitting layer. The nitride-based semiconductor laser device according to claim 1, wherein the nitride-based semiconductor laser device is provided. Forming on the main surface of the substrate and forming a first resonator end face at an end of the nitride-based semiconductor element layer having a light emitting layer;
A (000-1) plane extending at a predetermined angle with respect to the main surface in a region facing the end face of the first resonator, or a {A + B, A, -2A-B, 2A + B} plane (here A ≧ 0 and B ≧ 0 and at least one of A and B is an integer that is not 0)
Forming a second resonator end face extending in a direction substantially perpendicular to the main surface at an end opposite to the first resonator end face.   The step of forming the end face of the first resonator and the step of forming the end face of the second resonator include at least the end face of the first resonator or the end face of the second resonator by crystal growth of the nitride-based semiconductor element layer. The nitride-based semiconductor laser device according to claim 7, comprising a step of forming any one of them, and a step of forming at least one of the first resonator end surface and the second resonator end surface by etching. Manufacturing method.