JP5172322B2 - Nitride-based semiconductor light-emitting diode and manufacturing method thereof - Google Patents

Description

  The present invention relates to a nitride semiconductor light emitting diode and a method for manufacturing the same.

  Conventionally, a light emitting diode (LED) made of a nitride material such as gallium nitride has been put into practical use. In recent years, a light-emitting element formed on a polar surface ((0001) surface) of a GaN substrate takes into consideration that the light emission efficiency is lowered due to the influence of a large piezoelectric field, and thus a non-polar surface (m-plane ( An LED having a light emitting element layer formed on a 1-100) plane, an a-plane (11-20) plane, and the like, and a manufacturing method thereof have been proposed (see, for example, Patent Documents 1 and 2).

  Patent Document 1 discloses a semiconductor light-emitting element (LED) having a light-emitting portion made of a nitride-based compound semiconductor layer on a sapphire substrate and a method for manufacturing the same. In the semiconductor light emitting device described in Patent Document 1, a nitride-based compound semiconductor layer is formed by forming a side surface ((0001) crystal plane) perpendicular to the main surface of the sapphire substrate by etching. The light that propagates in the lateral direction inside the light emitting portion can also be extracted from the side surface of the compound semiconductor layer.

  Patent Document 2 discloses a nitride compound semiconductor light emitting device (LED) having a light emitting layer composed of a nitride compound semiconductor layer on a sapphire substrate and a method for manufacturing the same. In the nitride-based compound semiconductor light-emitting device described in Patent Document 2, a plurality of recesses are formed by etching in the nitride-based compound semiconductor layer, so that the light-emitting device can be formed from the side surface of the recess of the nitride-based compound semiconductor layer. It is configured to be able to take out light propagating laterally inside.

JP-A-8-64912 Japanese Patent Laid-Open No. 2001-24222

  However, in the semiconductor light emitting device (LED) and the manufacturing method thereof disclosed in Patent Documents 1 and 2 described above, side surfaces or a plurality of recesses are formed by etching on the nitride-based compound semiconductor layer on the substrate in the manufacturing process. Therefore, there is a problem that the manufacturing process becomes complicated. Further, since it is necessary to use dry etching in the step of forming the side surface for extracting light (Patent Document 1) or a plurality of recesses (Patent Document 2), it is considered that the light emitting portion (light emitting layer) is likely to be damaged. . In this case, there is also a problem that the light extraction efficiency from the light emitting layer is lowered.

  In addition, in the semiconductor light emitting device and the manufacturing method thereof disclosed in Patent Documents 1 and 2, in order to form a nitride-based compound semiconductor layer on a flat main surface of a sapphire substrate in the manufacturing process, In the process of crystal growth, a certain degree of flatness is ensured on the upper surface (main surface) of the semiconductor layer. However, the semiconductor light emitting device manufacturing process disclosed in Patent Documents 1 and 2 has a problem that it is difficult to further improve the flatness of the semiconductor layer.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to suppress the complexity of the manufacturing process and improve the light extraction efficiency from the light emitting layer. It is also possible to provide a nitride-based semiconductor light-emitting diode capable of improving the flatness of a semiconductor layer and a method for manufacturing the same.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, a nitride-based semiconductor light-emitting diode according to a first aspect of the present invention includes a substrate having a recess formed on the main surface, a light-emitting layer on the main surface of the substrate, and one of the recesses. 1st side which consists of the (000-1) plane formed from the inner surface of this, and the 2nd side surface formed from the other inner surface of a crevice in the field which counters the 1st side A physical semiconductor layer.

  In the nitride-based semiconductor light-emitting diode according to the first aspect of the present invention, as described above, the substrate is formed with a recess formed on the main surface, and the inner surface of one of the recesses is formed on the main surface of the substrate. The nitride-based semiconductor layer includes a nitride-based semiconductor layer including a first side formed from the (000-1) plane and a second side formed from the other inner surface of the recess. A first side surface and a second side surface are formed starting from the inner side surface of the recess formed in advance on the substrate. That is, unlike the case where the first side surface or the second side surface is formed by etching on a nitride-based semiconductor layer laminated on a flat substrate without a recess or the like in the manufacturing process, the etching processing is performed. Since it is not necessary, it is possible to prevent the manufacturing process of the nitride semiconductor light emitting diode from becoming complicated. Further, since the first side surface and the second side surface of the nitride-based semiconductor layer are not formed by dry etching or the like, the light emitting layer or the like is hardly damaged in the manufacturing process. Thereby, the extraction efficiency of light from the light emitting layer can be improved.

  Further, a substrate having a concave portion formed on the main surface, a first side surface comprising a (000-1) surface formed on one of the inner surfaces of the concave portion on the main surface of the substrate, and the other inner surface of the concave portion And a nitride-based semiconductor layer including a second side surface formed starting from the top surface of the growth layer (the main surface of the nitride-based semiconductor layer) when the nitride-based semiconductor layer is crystal-grown on the substrate. The growth rate of the first side surface starting from one inner side surface of the recess and the second side surface starting from the other inner side surface of the recess is slower than the growth rate at which the surface) grows. The upper surface (main surface) of the substrate grows while maintaining flatness. As a result, 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 nitride-based semiconductor layer in the case where the end surface composed of the first side surface and the second side surface is not formed. it can.

  In the nitride-based semiconductor light-emitting diode according to the first aspect, preferably, one inner surface of the recess includes a (000-1) plane. If comprised in this way, when forming the nitride-type semiconductor layer which has a 1st side surface which consists of (000-1) plane on the main surface of a board | substrate, one of the recessed parts which consist of (000-1) plane Since the (000-1) plane of the nitride-based semiconductor layer is formed so as to take over the side surface, the first side surface composed of the (000-1) plane can be easily formed on the substrate.

  In the nitride-based semiconductor light-emitting diode according to the first aspect, preferably, the first side surface and the second side surface are formed of a crystal growth surface of the nitride-based semiconductor layer. If comprised in this way, the two types of growth surface (end surface) of the said 1st side surface and the 2nd side surface can each be formed simultaneously with the crystal growth of a nitride type semiconductor layer.

  In the nitride-based semiconductor light-emitting diode according to the first aspect, preferably, the second side surface is a {A + B, A, −2A−B, 2A + B} plane (where A ≧ 0 and B ≧ 0, and An integer in which at least one of A and B is not 0). If comprised in this way, the surface (main surface) of the growth layer of the nitride-type semiconductor layer in the case of forming the side surface (end surface) which does not correspond to a {A + B, A, -2A-B, 2A + B} surface on a board | substrate In comparison, the surface (upper surface) of the growth layer in the case where the second side surface composed of the {A + B, AB, -2A, 2A + B} plane is formed on the substrate can be formed so as to ensure flatness. it can. Further, the {A + B, A, -2A-B, 2A + B} plane has a slower growth rate than the main surface of the nitride-based semiconductor layer, so that the second side surface can be easily formed by crystal growth.

  In the nitride semiconductor light emitting diode according to the first aspect, preferably, the substrate is made of a nitride semiconductor. If comprised in this way, the 1st side surface which consists of (000-1) plane, and {A + B, A, -2A-B using the crystal growth of a nitride-type semiconductor layer on the board | substrate which consists of nitride-type semiconductors A nitride-based semiconductor layer having a second side surface composed of a 2A + B} plane can be easily formed.

  In the nitride-based semiconductor light-emitting diode according to the first aspect, preferably, at least one of the first side surface and the second side surface is formed so as to form an obtuse angle with respect to the main surface of the nitride-based semiconductor layer. . If comprised in this way, the area | region (upper area | region of the recessed part of a board | substrate) where the 1st side surface and 2nd side surface of a nitride type semiconductor layer oppose will spread toward the upper surface of a nitride type semiconductor layer from a board | substrate. Since it is formed, light from the light emitting layer can be easily extracted not only through the top surface of the nitride-based semiconductor layer but also through the first side surface or the second side surface inclined with respect to the main surface of the substrate. Thereby, the luminous efficiency of the nitride-based semiconductor light-emitting diode can be further improved.

In the nitride-based semiconductor light-emitting diode according to the first aspect, preferably, the substrate includes a base substrate and a base layer formed on the base substrate and made of AlGaN, and the lattice constants of the base substrate and the base layer are set as follows: When c ₁ and c ₂ are set, respectively, there is a relationship of c ₁ > c ₂ , and the first side surface and the second side surface are substantially located on the (0001) plane of the underlayer and the main surface of the substrate, respectively. It is formed starting from the inner surface of the crack formed to extend in parallel. With this configuration, when forming the base layer made of AlGaN on the base substrate, the lattice constant c ₂ of the base layer is smaller than the lattice constant c _{1 of the} base substrate (c ₁ > c ₂ ). tensile stress is caused inside the underlayer in response to the lattice constant c ₁ on the substrate side. As a result, when the thickness of the underlayer is equal to or greater than a predetermined thickness, the underlayer cannot withstand this tensile stress and cracks are formed in the underlayer. As a result, the inner side surface (the inner side surface of one of the recesses) composed of the (000-1) surface that serves as a reference for forming the first side surface ((000-1) surface) of the nitride-based semiconductor layer on the base layer Can be easily formed on the underlayer.

  A method for manufacturing a nitride-based semiconductor light-emitting diode according to a second aspect of the present invention includes a step of forming a recess in a main surface of a substrate, a light-emitting layer on the main surface of the substrate, and one inner surface of the recess. A nitride-based semiconductor layer is formed by including a first side surface having a (000-1) plane as a starting point and a second side surface starting from the other inner side surface of the recess in a region facing the first side surface. A process.

  In the method for manufacturing a nitride-based semiconductor light-emitting diode according to the second aspect of the present invention, as described above, the step of forming a recess on the main surface of the substrate and the one inner surface of the recess on the main surface of the substrate are started. And a step of forming a nitride-based semiconductor layer by including a first side surface comprising the (000-1) plane and a second side surface starting from the other inner side surface of the recess. In the system semiconductor layer, a first side surface and a second side surface starting from the inner side surface of a recess formed in advance in the substrate are formed. That is, unlike the case where the first side surface or the second side surface is formed by etching on a nitride semiconductor layer stacked on a flat substrate having no recesses or the like in the manufacturing process, etching processing is required. Therefore, the complexity of the manufacturing process of the nitride-based semiconductor light-emitting diode can be suppressed. Further, since the first side surface and the second side surface of the nitride-based semiconductor layer are not formed by dry etching or the like, the light emitting layer or the like is hardly damaged in the manufacturing process. Thereby, the extraction efficiency of light from the light emitting layer can be improved.

  A step of forming a recess on the main surface of the substrate; a first side surface comprising a (000-1) plane starting from one inner surface of the recess on the main surface of the substrate; and the other inner surface of the recess. And a step of forming a nitride-based semiconductor layer by including the second side surface as a starting point, so that the upper surface of the growth layer (nitride-based semiconductor) when the nitride-based semiconductor layer is crystal-grown on the substrate The growth rate at which the first side surface starting from one inner surface of the recess and the second side surface starting from the other inner surface of the recess are slower than the growth rate at which the main surface of the layer grows. The upper surface (main surface) of the growth layer grows while maintaining flatness. As a result, 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 nitride-based semiconductor layer in the case where the end surface composed of the first side surface and the second side surface is not formed. it can.

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

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of a light-emitting diode chip according to the present invention. Referring to FIG. 1, before describing a specific embodiment of the present invention, a schematic configuration of a light-emitting diode chip according to the present invention will be described using a light-emitting diode chip 10 as an example.

  As shown in FIG. 1, the light emitting diode chip 10 has a light emitting layer 2 formed on a first semiconductor 1. A second semiconductor 3 is formed on the light emitting 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 layer” of the present invention, and the light-emitting layer 2 and the second semiconductor 3 are respectively the “nitride-based semiconductor layer” of the present invention. It is an example.

  Here, generally, a light emitting 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 the structure, it is possible to easily confine carriers in the light emitting layer 2 and to improve the light emission efficiency of the light emitting diode chip 10. Further, by making the light emitting layer 2 have a single quantum well 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 light emitting layer 2 or a tensile strain in the in-plane direction, the deterioration of crystallinity is suppressed. Is done. The light emitting 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 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 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 layer having a-plane and m-plane as main surfaces is formed can be used as the substrate.

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

  As the light emitting layer 2 of the quantum well, 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.

  Further, the second electrode 5 may be formed in a partial region on the second semiconductor 3. When the light-emitting diode chip 10 is a light-emitting diode, the electrode (in this case, the second electrode 5) formed on the light emission side (upper surface side) preferably has translucency.

  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 a semiconductor light emitting device is formed using the manufacturing process of the present invention. Next, with reference to FIG. 2, the plane orientation of the substrate in the case of forming a semiconductor light emitting element using the method for forming a nitride-based semiconductor 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 cross-sectional view illustrating a structure of a light emitting diode chip according to the first embodiment of the present invention. The structure of the light-emitting diode chip 30 according to the first embodiment will be described with reference to FIG.

  The light-emitting diode chip 30 according to the first embodiment is made of a nitride semiconductor having a wurtzite structure having an a-plane ((11-20) plane) as a main surface. The shape of the light-emitting diode chip 30 has a square shape, a rectangular shape, a rhombus shape, a parallelogram shape, or the like when viewed in plan (viewed from the upper surface side of the light-emitting diode chip 30).

In the light emitting diode chip 30, as shown in FIG. 3, a light emitting element layer 12 is formed on an n-type GaN substrate 11 having a thickness of about 100 μm. The light emitting element layer 12 includes an n-type cladding layer 13 made of n-type Al _0.03 Ga _0.97 N having a thickness of about 0.5 μm, and Ga _0.7 In _{0. A} light emitting layer 14 having an MQW structure in which a well layer (not shown) made of ₃ N and a barrier layer (not shown) made of Ga _0.9 In _0.1 N are stacked is formed. A p-type cladding layer 15 that also serves as a p-type contact layer made of p-type GaN having a thickness of about 0.2 μm is formed on the light emitting layer 14. The n-type GaN substrate 11 is an example of the “substrate” in the present invention, and the light-emitting element layer 12, the n-type cladding layer 13, the light-emitting layer 14, and the p-type cladding layer 15 are each a “nitride” in the present invention. It is an example of a “system semiconductor layer”.

  Here, in the first embodiment, from the n-type cladding layer 13 to the p-type cladding layer 15, the crystal growth surface 12 a composed of the (000-1) plane of the light emitting element layer 12 and the crystal growth composed of the (11-22) plane. A recess 20 is formed by the surface 12b. The crystal growth surface 12a and the crystal growth surface 12b are examples of the “first side surface” and the “second side surface” of the present invention, respectively. Further, the crystal growth surface 12a takes over the inner side surface 21a formed of the (000-1) plane of the groove portion 21 formed in advance on the main surface of the n-type GaN substrate 11 during the manufacturing process described later, so as to take over the n-type GaN substrate 11. It is formed so as to extend in a direction substantially perpendicular to the main surface ([11-20] direction). Further, the crystal growth surface 12b is an inclined surface starting from the inner side surface 21b of the groove portion 21, and is formed to form an obtuse angle with respect to the upper surface (main surface) of the light emitting element layer 12. The groove portion 21 and the inner side surface 21a are examples of the “recessed portion” and “one inner side surface of the recessed portion” of the present invention, respectively. In FIG. 3, for the sake of illustration, the reference numerals of the inner side surface 21 a and the inner side surface 21 b are shown only in some of the groove portions 21 in the drawing.

An n-side electrode 16 is formed on the lower surface of the n-type GaN substrate 11. In addition, an insulating film 22 such as SiO ₂ that is transparent to the emission wavelength is formed in the recess 20, and a translucent p-side electrode 17 is provided so as to cover the insulating film 22 and the p-type cladding layer 15. Is formed.

  4 to 6 are a plan view and a cross-sectional view for explaining a manufacturing process of the light-emitting diode chip according to the first embodiment shown in FIG. A manufacturing process for the light-emitting diode chip 30 according to the first embodiment is now described with reference to FIGS.

  First, as shown in FIG. 4, a width of about 5 μm in the [0001] direction (A direction) is formed on the main surface composed of the a-plane ((11-20) plane) of the n-type GaN substrate 11 using an etching technique. A plurality of grooves 21 having W1 and a depth of about 2 μm and extending in the [1-100] direction (B direction) are formed. In FIG. 4, a thick hatched portion is a region etched as the groove portion 21. The groove portions 21 are formed in a stripe shape in the A direction at a period of about 50 μm (= W1 + L1 (L1 = about 45 μm)).

  Here, in the manufacturing process of the first embodiment, as shown in FIG. 5, the groove portion 21 is made of a (000-1) plane substantially perpendicular to the (11-20) plane of the n-type GaN substrate 11. An inner side surface 21a and an inner side surface 21b made of a (0001) plane substantially perpendicular to the (11-20) plane of the n-type GaN substrate 11 are formed. The inner surface 21b is an example of the “other inner surface of the recess” in the present invention.

  Next, an n-type cladding layer 13, a light emitting layer 14, a p-type cladding layer 15, and the like are sequentially stacked on the n-type GaN substrate 11 having the groove portion 21 using a metal organic chemical vapor deposition method (MOCVD method). Thus, the light emitting element layer 12 is formed.

  At this time, in the first embodiment, as shown in FIG. 6, when the light emitting element layer 12 is grown on the n-type GaN substrate 11, the (000-1) plane of the groove 21 extending in the [1-100] direction. In the inner side surface 21a, the light emitting element layer 12 has a crystal growth surface 12a composed of a (000-1) plane extending in the [11-20] direction (C2 direction) so as to take over the (000-1) plane of the groove 21. The crystal grows while forming. Further, on the (0001) plane (inner side surface 21b) side facing the (000-1) plane of the groove portion 21, the light emitting element layer 12 is inclined at a predetermined angle with respect to the [11-20] direction (C2 direction). The crystal grows while forming a crystal growth surface (facet) 12b composed of a (11-22) plane extending in the direction. Thereby, the crystal growth surface 12b is formed so as to form an obtuse angle with respect to the upper surface (main surface) of the light emitting element layer 12.

  Thereafter, as shown in FIG. 3, the crystal growth surface 12 a ((000-1) plane) and the crystal growth surface 12 b ((11-22) plane) of the light emitting element layer 12 are included (including the groove portion 21). An insulating film 22 is formed so as to fill a region above the groove portion 21. Then, the p-side electrode 17 is formed on the upper surfaces of the insulating film 22 and the light emitting element layer 12, and the n-side electrode 16 is formed on the lower surface of the n-type GaN substrate 11. In this way, the light emitting diode chip 30 according to the first embodiment shown in FIG. 3 is formed.

  In the first embodiment, as described above, the n-type GaN substrate 11 having the groove portion 21 formed on the main surface and the inner surface 21a of the groove portion 21 are formed on the main surface of the n-type GaN substrate 11 as a starting point ( The light emitting element layer 12 includes a light emitting element layer 12 including a crystal growing face 12a composed of a (000-1) plane and a crystal growing face 12b formed with the inner side face 21b of the groove 21 as a starting point. A crystal growth surface 12a and a crystal growth surface 12b are formed starting from inner side surfaces 21a and 21b of a groove portion 21 formed in advance in the type GaN substrate 11, respectively. That is, unlike the case where the crystal growth surface 12a or the crystal growth surface 12b as described above is formed by etching on a nitride-based semiconductor layer stacked on a flat substrate having no recess or the like in the manufacturing process, etching is performed. Since processing is not required, it is possible to suppress the manufacturing process of the light emitting diode chip 30 from becoming complicated. Further, since the crystal growth surface 12a and the crystal growth surface 12b of the light emitting element layer 12 are not formed by dry etching or the like, the light emitting layer 14 and the like are hardly damaged in the manufacturing process. Thereby, the extraction efficiency of the light from the light emitting layer 14 can be improved.

  In the first embodiment, the n-type GaN substrate 11 having the groove portion 21 formed on the main surface and the inner surface 21a of the groove portion 21 are formed on the main surface of the n-type GaN substrate 11 (000-1). ) And a light-emitting element layer 12 including a crystal growth surface 12b formed from the inner side surface 21b of the groove 21 as a starting point, so that the light-emitting element layer 12 is formed on the n-type GaN substrate 11. The crystal growth surface 12a starting from the inner side surface 21a of the groove 21 and the inner side surface 21b of the groove 21 are higher than the growth rate at which the upper surface of the growth layer (the main surface of the light emitting element layer 12) grows. Since the growth rate at which the crystal growth surface 12b as the starting point is formed is slow, the upper surface (main surface) of the growth layer grows while maintaining flatness. Thereby, the flatness of the surface (upper surface) of the light emitting element layer 12 having the light emitting layer 14 as compared with the growth layer surface of the light emitting element layer when the end face composed of the crystal growth surface 12a and the crystal growth surface 12b is not formed. Can be further improved.

  In the first embodiment, the inner surface 21 a of the groove 21 is configured to be a (000-1) plane, whereby a crystal having a (000-1) plane on the main surface of the n-type GaN substrate 11. When forming the light emitting element layer 12 having the growth surface 12a, the (000-1) plane of the light emitting element layer 12 is formed so as to take over the (000-1) plane of the inner surface 21a of the groove portion 21. The crystal growth surface 12a composed of the (000-1) plane can be easily formed on the n-type GaN substrate 11.

  Further, in the first embodiment, the crystal growth surface 12a and the crystal growth surface 12b of the light emitting element layer 12 are configured to be composed of the crystal growth surface of the light emitting element layer 12, whereby the crystal growth surface 12a and the crystal growth surface are formed. Two types of crystal growth surfaces (end surfaces) 12b can be formed simultaneously with the crystal growth of the light emitting element layer 12, respectively.

  Further, in the first embodiment, the crystal growth surface 12b is configured to have a (11-22) plane, whereby a side surface (such as a (11-22) plane that does not correspond to a facet on the n-type GaN substrate 11 ( Compared with the surface (main surface) of the growth layer of the light emitting element layer 12 in the case of forming the end face), a facet (crystal growth surface 12b) composed of (11-22) plane is formed on the n-type GaN substrate 11. In this case, the surface (upper surface) of the growth layer can be formed so as to ensure flatness. Further, since the crystal growth surface 12b has a slower growth rate than the main surface of the light emitting element layer 12, the crystal growth surface 12b can be easily formed by crystal growth.

  In the first embodiment, the light emitting element layer 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. Using the crystal growth of 12, the light emitting element layer 12 having the crystal growth surface 12a composed of the (000-1) plane and the crystal growth surface 12b composed of the (11-22) plane can be easily formed.

  In the first embodiment, the crystal growth surface 12b of the light-emitting element layer 12 is formed so as to form an obtuse angle with respect to the main surface ((11-20) plane) of the light-emitting element layer 12. A plurality of recesses 20 (an upper region of the groove portion 21 including the groove portion 21 of the n-type GaN substrate 11) where the crystal growth surface 12 a and the crystal growth surface 12 b of the layer 12 face each other are formed from the n-type GaN substrate 11 to the light emitting element layer 12. Since it is formed so as to spread toward the upper surface, light from the light emitting layer 14 is easily extracted not only through the upper surface of the light emitting element layer 12 but also through the crystal growth surface 12 b inclined with respect to the main surface of the n-type GaN substrate 11. be able to. Thereby, the light emission efficiency of the light emitting diode chip 30 can be further improved.

(Second Embodiment)
FIG. 7 is a cross-sectional view illustrating a structure of a light emitting diode chip according to a second embodiment of the present invention. 8 to 10 are a cross-sectional view and a plan view for explaining a manufacturing process of the light-emitting diode chip according to the second embodiment shown in FIG. With reference to FIGS. 7 to 10, in the manufacturing process of the light-emitting diode chip 40 according to the second embodiment, unlike the first embodiment, an underlayer 50 made of AlGaN is formed on an n-type GaN substrate 41. A case where the light emitting element layer 42 is formed will be described. The n-type GaN substrate 41 is an example of the “underlying substrate” in the present invention.

  The light emitting diode chip 40 according to the second embodiment is made of a wurtzite nitride semiconductor having a (11-2-2) plane as a main surface. Moreover, the shape of the light emitting diode chip 40 has a square shape, a rectangular shape, a rhombus shape, a parallelogram shape, or the like when viewed in plan (viewed from the upper surface side of the light emitting diode chip 40).

Here, in the manufacturing process of the light-emitting diode chip 40 according to the second embodiment, as shown in FIG. 8, Al ₀ .4 having a thickness of about 3 μm to about 4 μm is formed on an n-type GaN substrate 41 having a thickness of about 100 μm _{. An} underlayer 50 made of ₀₅ Ga _0.95 N is grown. When the base layer 50 is crystal-grown, since the lattice constant c ₂ of the base layer 50 is smaller than the lattice constant c ₁ of the n-type GaN substrate 41 (c ₁ > c ₂ ), the base layer reaches a predetermined thickness. 50, tension in response to the lattice constant _{c 1} of the n-type GaN substrate 41 in the interior of the base layer 50 stress R (see FIG. 8) is generated. As a result, a crack 51 as shown in FIG. 8 is formed in the underlayer 50 as the underlayer 50 locally shrinks in the A direction. Here, 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 51 is formed between the (0001) plane of the foundation layer 50 and n. The GaN substrate 41 is easily formed in the [1-100] direction (B direction) parallel to the (11-2-2) plane of the main surface. Note that FIG. 8 schematically shows a state in which the crack 51 is spontaneously formed in the underlayer 50.

  Further, when the n-type GaN substrate 41 in which the crack 51 is formed is viewed in a plan view, the crack 51 is in the [1-100] direction substantially orthogonal to the A direction of the n-type GaN substrate 41 as shown in FIG. It is formed to extend in a stripe shape along (B direction). The crack 51 is an example of the “concave portion” in the present invention.

Thereafter, as shown in FIG. 10, an n-type cladding layer 43 made of n-type GaN having a thickness of about 0.5 μm is formed on the underlayer 50 by a manufacturing process similar to that of the first embodiment, and about 2 nm. A light emitting layer made of MQW in which a well layer (not shown) made of Ga _0.7 In _0.3 N having a thickness and a barrier layer (not shown) made of Ga _0.9 In _0.1 N are stacked. The light emitting element layer 42 is formed by sequentially stacking 44 and a p-type cladding layer 45 serving also as a p-type contact layer made of p-type GaN having a thickness of about 0.2 μm. The light emitting element layer 42, the n-type cladding layer 43, the light emitting layer 44, and the p-type cladding layer 45 are examples of the “nitride-based semiconductor layer” in the present invention.

  At this time, in the second embodiment, when the light emitting element layer 42 is grown on the n-type GaN substrate 41, the light emitting element layer 12 is formed on the inner side surface 51a of the crack 51 extending in a stripe shape in the [1-100] direction. , While forming a crystal growth surface (facet) 42a composed of a (000-1) plane extending in a direction inclined by a predetermined angle with respect to the [11-2-2] direction (C2 direction) of the n-type GaN substrate 41 grow up. In addition, on the side of the inner surface 51b facing the inner surface 51a of the crack 51, the light emitting element layer 42 is inclined at a predetermined angle with respect to the [11-2-2] direction (C2 direction) of the n-type GaN substrate 41. The crystal grows while forming a crystal growth surface (facet) 42b consisting of a (11-22) plane extending in the direction. The inner side surface 51a and the inner side surface 51b are examples of “one inner side surface of the recess” and “the other inner side surface of the recess” in the present invention, respectively, and the crystal growth surface 42a and the crystal growth surface 42b are respectively These are examples of the “first side surface” and the “second side surface” of the present invention. Thereby, the crystal growth surfaces 42a and 42b are formed so as to form an obtuse angle with respect to the upper surface (main surface) of the light emitting element layer 12, respectively.

Thereafter, as shown in FIG. 7, the recess 52 (the upper portion of the crack 51) sandwiched between the crystal growth surface 42a composed of the (000-1) plane and the crystal growth surface 42b composed of the (11-22) plane of the light emitting element layer 42. An insulating film 22 such as SiO ₂ that is transparent with respect to the emission wavelength is formed so as to fill the region. Then, the p-side electrode 47 is formed on the upper surfaces of the insulating film 22 and the light emitting element layer 42, and the n-side electrode 46 is formed on the lower surface of the n-type GaN substrate 41. In this manner, the light emitting diode chip 40 according to the second embodiment shown in FIG. 7 is formed.

  In the second embodiment, as described above, the n-type GaN substrate 41 having the crack 51 formed in the underlayer 50 and the inner surface 51a of the crack 51 are formed on the main surface of the n-type GaN substrate 41 as a starting point. The light emitting element layer 42 includes a light emitting element layer 42 including a crystal growing surface 42a composed of a (000-1) plane and a crystal growing surface 42b formed from the inner side surface 51b of the crack 51. On the n-type GaN substrate 41, a crystal growth surface 42a and a crystal growth surface 42b are formed starting from the inner side surfaces 51a and 51b of the crack 51 of the underlying layer 50 formed in advance. That is, unlike the case where the crystal growth surface 42a or the crystal growth surface 42b is formed by etching on a nitride-based semiconductor layer stacked on a flat substrate having no recess or the like in the manufacturing process, etching is performed. Since processing is not required, it is possible to suppress the manufacturing process of the light emitting diode chip 40 from becoming complicated. Further, since the crystal growth surface 42a and the crystal growth surface 42b of the light emitting element layer 42 are not formed by dry etching or the like, the light emitting layer 44 and the like are hardly damaged in the manufacturing process. Thereby, the light extraction efficiency from the light emitting layer 44 can be improved.

  In the second embodiment, the n-type GaN substrate 41 with the crack 51 formed in the underlayer 50 is formed on the main surface of the n-type GaN substrate 41 with the inner surface 51a of the crack 51 as a starting point (000− 1) The light emitting element layer 42 includes the light emitting element layer 42 including the crystal growing face 42a formed of a plane and the crystal growing face 42b formed with the inner side face 51b of the crack 51 as a starting point. The crystal growth surface 42a starting from the inner side surface 51a of the crack 51 and the inner side surface 51b of the crack 51 are higher than the growth rate at which the upper surface of the growth layer (the main surface of the light emitting element layer 42) grows when the crystal is grown thereon. Since the growth rate at which each of the crystal growth surfaces 42b 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 (upper surface) of the light emitting element layer 42 having the light emitting layer 44 as compared with the growth layer surface of the light emitting element layer when the end face composed of the crystal growth surface 42a and the crystal growth surface 42b is not formed. Can be further improved.

In the second embodiment, the underlying layer 50 made of AlGaN on the n-type GaN substrate 41 is formed, the lattice constant _{c 1} of the n-type GaN substrate 41, and a lattice constant _{c 2} of the underlayer 50, c ₁ > c ₂ , and the crystal growth surface 42 a and the crystal growth surface 42 b of the light emitting element layer 42 are formed by using the inner side surfaces 51 a and 51 b of the crack 51 as starting points, respectively. When forming the base layer 50 made of AlGaN on the n-type GaN substrate 41, the lattice constant c ₂ of the base layer 50 is smaller than the lattice constant c ₁ of the n-type GaN substrate 41 (c ₁ > c ₂ ). A tensile stress R is generated inside the underlayer 50 in an attempt to match the lattice constant c ₁ on the n-type GaN substrate 41 side. As a result, when the thickness of the underlayer 50 is equal to or greater than a predetermined thickness, the underlayer 50 cannot withstand this tensile stress R, and a crack 51 is formed in the underlayer 50. Thus, the inner side surface serving as a reference for crystal growth of the crystal growth surface 42a ((000-1) surface) and the crystal growth surface 42b ((11-22) surface) of the light emitting element layer 42 on the base layer 50, respectively. 51a and 51b can be easily formed in the foundation layer 50.

  In the second embodiment, the crystal growth surface 42 a ((000-1) plane) and the crystal growth surface 42 b ((11-22) plane) of the light emitting element layer 42 are formed of the crystal growth surface of the light emitting element layer 42. With such a configuration, two types of flat crystal growth surfaces (end surfaces) of the crystal growth surface 42 a and the crystal growth surface 42 b can be easily formed simultaneously with the crystal growth of the light emitting element layer 42.

  In the second embodiment, the crystal growth surfaces 42 a and 42 b of the light emitting element layer 42 are formed so as to form an obtuse angle with respect to the main surface ((11-2-2) plane) of the light emitting element layer 42. As a result, a plurality of recesses 52 (the upper region of the crack 51 including the crack 51 on the n-type GaN substrate 41) where the crystal growth surface 42 a and the crystal growth surface 42 b of the light emitting element layer 42 face each other are separated from the n-type GaN substrate 41. Since it is formed so as to spread toward the upper surface of the light emitting element layer 42, the crystal growth surface in which the light from the light emitting layer 44 is inclined with respect to not only the upper surface of the light emitting element layer 42 but also the main surface of the n-type GaN substrate 41. It can be easily removed through 42a and 42b. Thereby, the luminous efficiency of the light emitting diode chip 40 can be further improved.

  The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

(Third embodiment)
FIG. 11 is a cross-sectional view illustrating the structure of a light emitting diode chip according to a third embodiment of the present invention. 12 and 13 are plan views for explaining a manufacturing process of the light-emitting diode chip according to the third embodiment shown in FIG. With reference to FIGS. 8 and 11 to 13, in the manufacturing process of the light-emitting diode chip 60 according to the third embodiment, unlike the second embodiment, the underlying layer 50 on the n-type GaN substrate 61 has a broken line shape. The case where the crack 71 in which the generation position of the crack is controlled by forming the scribe flaw 70 will be described. The n-type GaN substrate 61 is an example of the “underlying substrate” in the present invention, and the crack 71 is an example of the “concave portion” in the present invention.

  The light-emitting diode chip 60 according to the third embodiment is made of a wurtzite nitride semiconductor having a (1-10-2) plane as a main surface. Further, the shape of the light-emitting diode chip 60 has a square shape, a rectangular shape, a rhombus shape, a parallelogram shape, or the like when viewed in plan (from the upper surface side of the light-emitting diode chip 60).

  Here, in the manufacturing process of the light-emitting diode chip 60 in the third embodiment, as in the case shown in FIG. 8, the thickness (about approximately) on the n-type GaN substrate 61 (see FIG. 11). An underlayer 50 made of AlGaN having a thickness of about 3 μm to about 4 μm and a critical film thickness is grown. At this time, a tensile stress R (see FIG. 8) is generated in the underlayer 50 by the same action as in the second 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. 12, scribe scratches in the form of broken lines at intervals of about 50 μm in the [11-20] direction (B direction) substantially perpendicular to the A direction on the underlayer 50 by laser light or diamond points. 70 is formed. A plurality of scribe flaws 70 are formed in the A direction at a pitch of an interval L2. As a result, as shown in FIG. 13, the crack progresses in the base layer 50 in the region of the base layer 50 where the scribe scratch 70 is not formed, starting from the broken scribe scratch 70. As a result, a substantially linear crack 71 (see FIG. 13) that divides the underlayer 50 in the B direction is formed.

  At that time, the scribe flaw 70 is also divided in the depth direction (direction perpendicular to the paper surface of FIG. 13). As a result, an inner side surface 71 a (shown by a broken line) reaching the vicinity of the interface between the foundation layer 50 and the n-type GaN substrate 61 is formed in the crack 71. The inner side surface 71a is an example of “one inner side surface of the recess” in the present invention.

Thereafter, by a manufacturing process similar to that of the second embodiment, an n-type cladding layer 43 and a well layer (not shown) made of Ga _0.7 In _0.3 N having a thickness of about 2 nm are formed on the base layer 50. ) And a light emitting layer 44 made of MQW in which a barrier layer (not shown) made of Ga _0.9 In _0.1 N is laminated, and a p-type cladding layer 45 are sequentially laminated, whereby the light emitting element layer 42. Form.

  At this time, the light emitting element layer 42 on the n-type GaN substrate 61 extends in a direction inclined by a predetermined angle with respect to the [1-10-2] direction (C2 direction) of the n-type GaN substrate 61 (000-1). ) Plane and a (1-101) plane extending in a direction inclined by a predetermined angle with respect to the [1-10-2] direction (C2 direction) of the n-type GaN substrate 61. 42d is formed. The crystal growth surface 42c and the crystal growth surface 42d are examples of the “first side surface” and the “second side surface” of the present invention, respectively.

  The other manufacturing processes according to the third embodiment are the same as those of the second embodiment. In this way, the light emitting diode chip 60 according to the third embodiment shown in FIG. 11 is formed.

  In the manufacturing process of the third embodiment, as described above, when the crack 71 is formed, the base layer 50 is formed on the n-type GaN substrate 61 with a thickness of about the critical thickness, and then the base layer 50 is formed. By forming a plurality of broken-line-like (approximately 50 μm-interval) scribe scratches 70 extending in the [11-20] direction (B direction) at a pitch of the interval L2 in the A direction, The cracks 71 are formed in parallel to the B direction and at equal intervals along the A direction, starting from the scribe-shaped scratch 70. That is, as in the second embodiment, the light emitting diode chip 60 having a uniform light emitting area (see FIG. 11) can be more easily compared with the case where the semiconductor layers are stacked using the spontaneously formed cracks. ) Can be formed. The remaining effects of the third embodiment are similar to those of the aforementioned second embodiment.

(Fourth embodiment)
FIG. 14 is a cross-sectional view illustrating a structure of a light emitting diode chip according to a fourth embodiment of the present invention. FIG. 15 is a cross-sectional view for explaining a manufacturing process of the light-emitting diode chip according to the fourth embodiment shown in FIG. 14 and 15, in the manufacturing process of the light-emitting diode chip 80 according to the fourth embodiment, unlike the first embodiment, n having a main surface composed of an m-plane ((1-100) plane). A case where the light emitting element layer 12 is formed after forming the base layer 50 made of AlGaN on the type GaN substrate 81 will be described. The n-type GaN substrate 81 is an example of the “underlying substrate” in the present invention.

  The light-emitting diode chip 80 according to the fourth embodiment is made of a nitride semiconductor having a wurtzite structure whose main surface is an m-plane ((1-100) plane). Further, the shape of the light emitting diode chip 80 has a square shape, a rectangular shape, a rhombus shape, a parallelogram shape, or the like when viewed in plan (from the upper surface side of the light emitting diode chip 80).

Here, in the manufacturing process of the light-emitting diode chip 80 according to the fourth embodiment, as shown in FIG. 15, Al ₀ .4 having a thickness of about 3 μm to about 4 μm is formed on an n-type GaN substrate 81 having a thickness of about 100 μm _{. An} underlayer 50 made of ₀₅ Ga _0.95 N is grown. At that time, as in the second embodiment, a crack 51 is formed in the underlayer 50 due to a difference in lattice constant between the n-type GaN substrate 81 and the underlayer 50.

Thereafter, the n-type cladding layer 13 made of n-type Al _0.03 Ga _0.97 N having a thickness of about 0.5 μm is formed on the underlayer 50 by the same manufacturing process as in the first embodiment, and about 2 nm. And a MQW structure in which a well layer (not shown) made of Ga _0.7 In _0.3 N and a barrier layer (not shown) made of Ga _0.9 In _0.1 N are stacked. The light emitting element layer 12 is formed by sequentially laminating the light emitting layer 14 and the p-type cladding layer 15 also serving as a p-type contact layer made of p-type GaN having a thickness of about 0.2 μm.

  At this time, in the fourth embodiment, as shown in FIG. 15, when the light emitting element layer 12 is grown on the n-type GaN substrate 81, the crack 51 (000) extending in the [11-20] direction (B direction). -1) In the inner surface 51a composed of a plane, the light emitting element layer 12 is composed of a (000-1) plane extending in the [1-100] direction (C2 direction) so as to take over the (000-1) plane of the crack 51. The crystal grows while forming the crystal growth surface 12c. On the (0001) plane (inner side surface 51b) side facing the (000-1) plane of the crack 51, the light emitting element layer 12 is inclined at a predetermined angle with respect to the [1-100] direction (C2 direction). The crystal grows while forming a crystal growth surface (facet) 12d composed of a (1-101) plane extending in the direction. Thereby, the crystal growth surface 12d is formed so as to form an obtuse angle with respect to the upper surface (main surface) of the light emitting element layer 12. The crystal growth surface 12c and the crystal growth surface 12d are examples of the “first side surface” and the “second side surface” of the present invention, respectively.

Also in the fourth embodiment, the concave portion 20 (the crack 51 is sandwiched between the crystal growth surface 12c ((000-1) surface) and the crystal growth surface 12b ((1-101) surface) of the light emitting element layer 12. An insulating film 22 such as SiO ₂ that is transparent with respect to the emission wavelength is formed so as to fill the upper region of the crack 51 including it.

  Other manufacturing processes according to the fourth embodiment are the same as those in the first embodiment. In this way, the light emitting diode chip 80 according to the fourth embodiment shown in FIG. 14 is formed.

  The effect of the light-emitting diode chip 80 according to the fourth embodiment is the same as that of the first and second embodiments.

[Example]
16 and 17 are micrographs obtained by observing a crystal growth state of the nitride-based semiconductor layer on the n-type GaN substrate in the manufacturing process of the fourth embodiment shown in FIG. 14 using a scanning electron microscope. . With reference to FIG. 9, FIG. 16, and FIG. 17, an experiment conducted for confirming the effect of the fourth embodiment will be described.

  In this confirmation experiment, first, an MOCVD method is used on an n-type GaN substrate having a main surface made of an m-plane ((1-100) plane) using a manufacturing process similar to the manufacturing process of the fourth embodiment described above. Was used to form an underlayer made of AlGaN having a thickness of 3 μm to 4 μm. At this time, due to a difference in lattice constant between the n-type GaN substrate and the underlayer, cracks as shown in FIGS. 16 and 17 were formed in 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. In addition, as shown in FIG. 9, the cracks were formed in stripes along the [11-20] direction (B direction) orthogonal to the [0001] direction (A direction) of the n-type GaN substrate. confirmed.

  Next, a semiconductor layer made of GaN was epitaxially grown on the underlayer using MOCVD. As a result, as shown in FIG. 17, on the inner side surface of the (000-1) plane of the crack, while forming the (000-1) plane of GaN extending in the vertical direction so that the semiconductor layer takes over this plane orientation. Crystal growth was confirmed in the [1-100] (C2 direction) direction. Further, as shown in FIG. 17, it was confirmed that an inclined surface (facet) composed of the (1-101) plane of GaN was formed on the inner surface opposite to the (000-1) plane of the crack. It was. 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 result of the above confirmation experiment, in the method for forming a nitride-based semiconductor layer according to the present invention, the semiconductor layer (light-emitting layer) is formed on the semiconductor layer (light-emitting layer) without using an etching process or the like simultaneously with the formation of the semiconductor layer by crystal growth. It was confirmed that an end face (vertical side face and inclined face of the semiconductor layer) composed of a face and a (1-101) face can be formed. Further, in the process of crystal growth of the semiconductor layer, the growth rate of the portion where the (000-1) plane and the (1-101) plane are formed and the upper surface (main surface) of the semiconductor layer are in the direction of arrow C2 (FIG. 16). In addition to the flatness of the (000-1) plane and the (1-101) plane, the flatness of the upper surface (main surface) of the semiconductor layer can be improved. It was confirmed that it was possible.

(Fifth embodiment)
FIG. 18 is a cross-sectional view illustrating a structure of a light emitting diode chip according to a fifth embodiment of the present invention. Referring to FIG. 18, in the light-emitting diode chip 90 according to the fifth embodiment, unlike the first embodiment, an n-type 4H—SiC substrate 91 having a main surface composed of an m-plane ((1-100) plane). The case where the light emitting element layer 92 is formed is described above. The n-type 4H—SiC substrate 91 and the light emitting element layer 92 are examples of the “substrate” and “nitride-based semiconductor layer” of the present invention, respectively.

  The light-emitting diode chip 90 according to the fifth embodiment is made of a nitride semiconductor having a wurtzite structure whose main surface is an m-plane ((1-100) plane). The shape of the light-emitting diode chip 90 has a square shape, a rectangular shape, a rhombus shape, a parallelogram shape, or the like when viewed in plan (viewed from the upper surface side of the light-emitting diode chip 90).

In the light emitting diode chip 90, as shown in FIG. 18, a light emitting element layer 92 is formed on an n-type 4H—SiC substrate 91 having a thickness of about 100 μm. The light emitting element layer 92 includes an n-type cladding layer 93 made of n-type Al _0.03 Ga _0.97 N having a thickness of about 0.5 μm, and Ga _0.7 In _{0. A} light emitting layer 94 having an MQW structure in which a well layer (not shown) made of 3N and a barrier layer (not shown) made of Ga _0.9 In _0.1 N are stacked is formed. A p-type cladding layer 95 also serving as a p-type contact layer made of p-type GaN having a thickness of about 0.2 μm is formed on the light emitting layer 94. The n-type cladding layer 93, the light emitting layer 94, and the p-type cladding layer 95 are examples of the “nitride-based semiconductor layer” in the present invention.

  Here, in the fifth embodiment, from the n-type cladding layer 93 to the p-type cladding layer 95, the crystal growth surface 92a composed of the (000-1) plane of the light emitting element layer 92 and the crystal growth composed of the (1-101) plane. A recess 20 is formed by the surface 92b. The crystal growth surface 92a and the crystal growth surface 92b are examples of the “first side surface” and the “second side surface” of the present invention, respectively. In addition, the crystal growth surface 92a takes over the n-type 4H—SiC so as to take over the inner side surface 96a made of the (000-1) plane of the groove 96 formed in advance on the main surface of the n-type 4H—SiC substrate 91 during the manufacturing process. It is formed so as to extend in a direction substantially perpendicular to the main surface of the substrate 91 ([1-100] direction). The crystal growth surface 92b is an inclined surface starting from the inner side surface 96b of the groove portion 96, and is formed so as to form an obtuse angle with respect to the upper surface (main surface) of the light emitting element layer 92. The groove 96 and the inner side surfaces 96a and 96b are examples of the “concave portion”, “one inner side surface of the concave portion”, and “the other inner side surface of the concave portion” of the present invention, respectively. In FIG. 18, for the sake of illustration, the reference numerals of the inner side surface 96 a and the inner side surface 96 b are shown only in some of the groove portions 96 in the drawing.

An n-side electrode 16 is formed on the lower surface of the n-type 4H—SiC substrate 91. In addition, an insulating film 22 is formed in the recess 20, and a p-side electrode 17 having translucency is provided so as to cover the insulating film 22 such as SiO ₂ transparent to the emission wavelength and the p-type cladding layer 15. Is formed.

  The manufacturing process of the light-emitting diode chip 90 according to the fifth embodiment is the same as that of the first embodiment. The effects of the fifth embodiment are also the same as those of the first embodiment.

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

  For example, in the light-emitting diode chips according to the first to fifth embodiments, the light-emitting element layer (light-emitting element layer 12 and the like) is shown as being formed of a nitride-based semiconductor layer such as AlGaN or InGaN. However, the light-emitting element layer is not limited to this, and may be formed of a nitride semiconductor layer having a Wurtz structure made of AlN, InN, BN, TlN, or a mixed crystal thereof.

  In the light-emitting diode chip according to the first embodiment, the light-emitting element layer 12 is crystal-grown after forming the groove 21 on the main surface composed of the a-plane ((11-20) plane) of the n-type GaN substrate. However, the present invention is not limited to this. For example, grooves (recesses) are formed on the main surface perpendicular to the (000 ± 1) plane of an n-type GaN substrate such as an m-plane ((1-100) plane). A light emitting element layer may be formed above.

  Further, in the light-emitting diode chip according to the fourth embodiment, an example in which the crack 51 is spontaneously formed in the underlayer 50 using the lattice constant difference between the n-type GaN substrate 81 and the underlayer 50 is used. Although the present invention is not limited to this, as in the third embodiment, a crack in which the generation position of a crack is controlled by forming a broken-line-shaped scribe flaw on the underlayer on the n-type GaN substrate is shown. You may make it form.

In the light-emitting diode chips according to the first to fourth 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, and for example, the a-plane ((11-20) plane) is used. An r-plane ((1102) plane) sapphire substrate, or an a-plane ((11-20) plane) or m-plane ((1-100) plane) on which a nitride semiconductor as a main surface is grown in advance Alternatively, an a-plane SiC substrate or m-plane SiC substrate on which a nitride-based semiconductor to be grown 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 light-emitting diode chips according to the second to fourth embodiments, an example in which an n-type GaN substrate is used as a base substrate and a base layer made of AlGaN is formed on the n-type GaN substrate has been described. In addition to this, an InGaN substrate may be used as a base substrate, and a base layer made of GaN or AlGaN may be formed on the InGaN substrate.

  In the light-emitting diode chip according to the second and fourth embodiments, an example in which a crack is spontaneously formed in the underlayer using a difference in lattice constant between the n-type GaN substrate and the underlayer is shown. However, the present invention is not limited to this, and only the both ends in the B direction (see FIG. 9) of the base layer 50 (see FIG. 9) (regions corresponding to the ends in the B direction of the n-type GaN substrate 41) are scribed. 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.

  Further, in the light-emitting diode chip according to the third embodiment, an example in which the scribe flaws 70 for introducing cracks are formed in the underlayer 50 in the shape of broken lines (interval of about 50 μm) is shown, but the present invention is not limited to this. Scribe flaws may be formed at both ends of the formation 50 in the B direction (see FIG. 12) (regions corresponding to the ends of the n-type GaN substrate 61). Even if comprised in this way, the crack extended in a B direction can be introduce | transduced from the scribe flaw of both ends.

It is sectional drawing for demonstrating the schematic structure of the light emitting diode chip | tip 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 light-emitting device using the crystal orientation of a nitride-type semiconductor, and the manufacturing process in this invention. 1 is a cross-sectional view illustrating a structure of a light-emitting diode chip according to a first embodiment of the present invention. FIG. 6 is a plan view for explaining a manufacturing process for the light-emitting diode chip according to the first embodiment shown in FIG. 3; FIG. 4 is a cross-sectional view for explaining a manufacturing process of the light-emitting diode chip according to the first embodiment shown in FIG. 3. FIG. 4 is a cross-sectional view for explaining a manufacturing process of the light-emitting diode chip according to the first embodiment shown in FIG. 3. FIG. 6 is a cross-sectional view illustrating a structure of a light emitting diode chip according to a second embodiment of the present invention. FIG. 8 is an enlarged cross-sectional view for explaining a manufacturing process of the light-emitting diode chip according to the second embodiment shown in FIG. 7. FIG. 8 is an enlarged plan view for explaining a manufacturing process of the light-emitting diode chip according to the second embodiment shown in FIG. 7. FIG. 8 is a cross-sectional view for explaining a manufacturing process of the light-emitting diode chip according to the second embodiment shown in FIG. 7. It is sectional drawing for demonstrating the structure of the light emitting diode chip by 3rd Embodiment of this invention. FIG. 12 is a plan view for explaining a manufacturing process for the light-emitting diode chip according to the third embodiment shown in FIG. 11; FIG. 12 is a plan view for explaining a manufacturing process for the light-emitting diode chip according to the third embodiment shown in FIG. 11; FIG. 6 is a cross-sectional view illustrating a structure of a light emitting diode chip according to a fourth embodiment of the present invention. FIG. 15 is a cross-sectional view for explaining a manufacturing process of the light-emitting diode chip according to the fourth embodiment shown in FIG. 14. It is the microscope picture which observed the mode of crystal growth of the nitride-type semiconductor layer on the n-type GaN substrate in the manufacturing process of 4th Embodiment shown in FIG. 14 using the scanning electron microscope. It is the microscope picture which observed the mode of crystal growth of the nitride-type semiconductor layer on the n-type GaN substrate in the manufacturing process of 4th Embodiment shown in FIG. 14 using the scanning electron microscope. FIG. 7 is a cross-sectional view illustrating a structure of a light emitting diode chip according to a fifth embodiment of the present invention.

Explanation of symbols

1 First semiconductor (substrate, nitride-based semiconductor layer)
2 Light emitting layer (nitride semiconductor layer)
3 Second semiconductor (nitride semiconductor layer)
11, 41 n-type GaN substrate (substrate)
12, 42, 92 Light emitting element layer (nitride semiconductor layer)
12a, 42a, 92a Crystal growth surface (first side surface)
12b, 42b, 92b Crystal growth surface (second side surface)
13, 43, 93 n-type cladding layer (nitride-based semiconductor layer)
14, 44, 94 Light emitting layer (nitride semiconductor layer)
15, 45, 95 p-type cladding layer (nitride-based semiconductor layer)
21, 96 Groove (recess)
21a, 96a Inner surface (one inner surface of the recess)
21b, 96b Inner surface (the other inner surface of the recess)
50 Underlayer 51, 71 Crack (recess)
51a, 71a Inner surface (one inner surface of the recess)
51b, 71b Inner surface (the other inner surface of the recess)
61, 81 n-type GaN substrate (underlying substrate)
91 n-type 4H-SiC substrate (substrate)

Claims (8)

A substrate having a recess formed on the main surface;
On the main surface of the substrate, in a region facing the first side surface, a first side surface comprising a (000-1) surface having a light emitting layer and starting from one inner side surface of the recess. A nitride-based semiconductor light-emitting diode comprising a nitride-based semiconductor layer including a second side surface formed with the other inner side surface of the recess as a starting point.   2. The nitride-based semiconductor light-emitting diode according to claim 1, wherein one inner side surface of the recess includes a (000-1) plane.   The nitride-based semiconductor light-emitting diode according to claim 1, wherein the first side surface and the second side surface are formed of a crystal growth surface of the nitride-based semiconductor layer.   The second side surface is composed of {A + B, A, −2A−B, 2A + B} planes (where A ≧ 0 and B ≧ 0, and at least one of A and B is not 0). The nitride semiconductor light emitting diode according to any one of claims 1 to 3.   The nitride-based semiconductor light-emitting diode according to claim 1, wherein the substrate is made of a nitride-based semiconductor.   6. The device according to claim 1, wherein at least one of the first side surface and the second side surface is formed so as to form an obtuse angle with respect to a main surface of the nitride-based semiconductor layer. Nitride-based semiconductor light-emitting diodes. The substrate includes a base substrate and a base layer formed on the base substrate and made of AlGaN,
When the lattice constants of the base substrate and the base layer are c ₁ and c ₂ , respectively, the relationship is c ₁ > c ₂ ,
Each of the first side surface and the second side surface is formed starting from an inner side surface of a crack formed so as to extend substantially parallel to the (0001) surface of the base layer and the main surface of the substrate. The nitride semiconductor light emitting diode according to any one of claims 1 to 6. Forming a recess in the main surface of the substrate;
On the main surface of the substrate, a first side surface having a light emitting layer and having a (000-1) plane starting from one inner side surface of the concave portion, and the other side of the concave portion in a region facing the first side surface And a step of forming a nitride-based semiconductor layer by including a second side surface starting from the inner surface of the nitride-based semiconductor light-emitting diode.