JP2007200929A - Manufacturing method of semiconductor light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor light emitting element with which a nitride semiconductor layer can be obtained in short time without deteriorating a device characteristic. <P>SOLUTION: The manufacturing method of a semiconductor laser is provided with a process for forming a first nitride semiconductor layer on a main face 1a of a substrate 1, a process for forming a lift off layer 13 on a main face 11a of a substrate 11, a process for forming a second nitride semiconductor layer comprising a light emitting layer 17 on the lift off layer 13, a process for bonding the first nitride semiconductor layer and the second nitride semiconductor layer in a state where the main face 1a of the substrate 1 is confronted with the main face 11a of the substrate 11, and a process for separating the substrate 11 and the second nitride semiconductor layer by wet-etching the lift off layer 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor light emitting device, and more particularly to a method for manufacturing a semiconductor light emitting device including a nitride semiconductor layer containing GaN (gallium nitride).

  In recent years, blue-violet lasers have attracted attention as light sources for next-generation high-density recording optical disks, and there is an increasing demand for commercialization. Regarding a blue-violet laser, a GaN-based semiconductor has a band gap of 1.9 eV to 6.2 eV. Therefore, theoretically, laser oscillation of blue-violet light is possible, and its development is actively performed. A GaN-based semiconductor light-emitting element is manufactured by forming a laminated structure of a GaN-based semiconductor on a sapphire substrate using MOVPE (Metal Organic Vapor Phase Epitaxy).

  However, the GaN semiconductor layer and the sapphire substrate generally have different lattice constants of about 10%, and the thermal expansion coefficients are greatly different. For this reason, dislocations and thermal strains are likely to occur in a GaN-based semiconductor grown on a sapphire substrate due to lattice mismatch and differences in thermal expansion coefficients. Further, since the thermal conductivity of the sapphire substrate is as small as about 17 W / mK, there is a problem that the light emission output of the semiconductor light emitting element is saturated by heat.

  Therefore, conventionally, after a laminated structure of a GaN-based semiconductor is formed on a sapphire substrate, GaN is applied to a substrate made of a material having a thermal expansion coefficient close to that of a GaN-based semiconductor and high thermal conductivity, such as copper tungsten. The manufacturing method which affixed a system semiconductor and removes a sapphire substrate after that was employ | adopted.

  As a method of removing the sapphire substrate from the GaN-based semiconductor, a method of removing the sapphire substrate by polishing can be considered.

Further, for example, in Japanese Patent Application Laid-Open No. 2004-112000 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2004-87775 (Patent Document 2), a method of removing a sapphire substrate from a GaN-based semiconductor by irradiating laser light (Laser Lift-off method) is disclosed. In Patent Document 1, an AlGaN layer as a lift-off layer and a GaN layer are stacked on a sapphire substrate, and then the AlGaN layer is irradiated with laser light to separate the sapphire substrate from the GaN-based semiconductor layer. Yes. In Patent Document 2, a semiconductor layer made of GaN is formed on a substrate made of sapphire, and the semiconductor layer is irradiated with laser light to separate the substrate from the semiconductor layer. In the laser lift-off method, light energy of laser light is converted into thermal energy and absorbed by the absorption layer of the laser light, the absorption layer generates heat, and the lift-off layer or the GaN layer is melted by the heat.
JP 2004-112000 A Japanese Patent Laid-Open No. 2004-87775

  However, since sapphire is a very hard material, there is a problem that it takes a long time to remove the sapphire substrate by polishing. Further, the laser lift-off method has a problem that device characteristics are deteriorated by heat. In particular, since unevenness occurs in the melted portion, it is necessary to level the surface when forming an electrode or the like on the GaN layer. These problems are not limited to the case where the GaN layer is formed, but are common problems when the nitride semiconductor layer including the light emitting layer is formed.

  Accordingly, an object of the present invention is to provide a method for manufacturing a semiconductor light-emitting element capable of obtaining a nitride semiconductor layer in a short time without deteriorating device characteristics.

  A method for manufacturing a semiconductor light emitting device according to one aspect of the present invention includes a step of forming a lift-off layer on a substrate, a step of forming a nitride semiconductor layer including a light-emitting layer on the lift-off layer, and wet etching the lift-off layer. Thus, a separation step of separating the substrate and the nitride semiconductor layer is provided.

  According to the method for manufacturing a semiconductor light emitting device according to one aspect of the present invention, the substrate and the nitride semiconductor layer can be separated without causing damage to the nitride semiconductor layer due to heat. Thereby, deterioration of device characteristics can be prevented. Moreover, since the substrate and the nitride semiconductor layer can be separated without melting, unevenness is not generated on the surface of the nitride semiconductor layer after separation. Furthermore, since it is not necessary to polish the substrate, a nitride semiconductor layer can be obtained in a short time. Therefore, a nitride semiconductor layer can be obtained in a short time without deteriorating device characteristics.

  Preferably, the method for manufacturing a semiconductor light emitting device according to one aspect of the present invention further includes an introduction part step for forming an introduction part for allowing an etchant used for wet etching to reach the lift-off layer before the separation process. ing.

  Since the lift-off layer is sandwiched between the substrate and the nitride semiconductor layer, the etching solution cannot be directly introduced into the main surface of the lift-off layer when there is no introduction portion, and the etching solution can be applied only from the end surface of the lift-off layer. be introduced. Since the thickness of the lift-off layer is usually several μm or less, the etching solution is difficult to be introduced from the end face of the lift-off layer. In contrast, by forming the introduction portion, the etching solution can be directly introduced into the main surface of the lift-off layer, and the time required for etching the lift-off layer can be shortened.

  Note that the introduction part may be a part for enabling the introduction of the etchant from at least the outside into the lift-off layer.

  Preferably, in the method for manufacturing a semiconductor light emitting device according to one aspect of the present invention, the introduction portion is a groove formed so as to reach the end face of the nitride semiconductor layer. Thereby, the etchant can be introduced from the end face of the nitride semiconductor layer.

  Preferably, in the method for manufacturing a semiconductor light emitting device according to one aspect of the present invention, the introduction portion is a hole formed so as to penetrate the nitride semiconductor layer and the substrate. Thereby, it is possible to introduce the etching solution from the surface of the substrate. Further, the flow rate of the etching solution can be controlled according to the hole diameter.

  In the method for manufacturing a semiconductor light emitting device according to one aspect of the present invention, preferably, in the introduction part step, the introduction part is formed in the nitride semiconductor layer using any one of dicing, dry etching, and laser irradiation. Thereby, the introduction part can be easily formed in a short time.

  Preferably, in the method for manufacturing a semiconductor light emitting device according to one aspect of the present invention, in the separation step, at least selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, dichromic acid, potassium hydroxide, and sodium hydroxide. The lift-off layer is etched while applying an electric field to an etching solution containing one kind. An etchant containing these substances is suitable for etching the lift-off layer.

  Preferably, in the method for manufacturing a semiconductor light emitting device according to one aspect of the present invention, the lift-off layer is selected from the group consisting of GaN (gallium nitride), AlN (aluminum nitride), InN (indium nitride), and GaMnN (manganese gallium nitride). A crystal containing at least one kind or a mixed crystal containing crystals.

  Since these materials have a lattice constant close to that of the nitride semiconductor layer, defects in the nitride semiconductor layer and internal stress in the nitride semiconductor layer can be suppressed.

  A method of manufacturing a semiconductor light emitting device according to another aspect of the present invention includes a step of forming a first nitride semiconductor layer on a main surface of a first substrate, and a step of forming a lift-off layer on the main surface of a second substrate. , Forming the second nitride semiconductor layer including the light emitting layer on the lift-off layer, and the first nitride semiconductor layer and the second substrate in a state where the main surface of the first substrate and the main surface of the second substrate face each other. A bonding step of bonding the nitride semiconductor layer and a separation step of separating the second substrate and the second nitride semiconductor layer by wet-etching the lift-off layer are provided.

  According to the method for manufacturing a semiconductor light emitting device according to another aspect of the present invention, a single nitride semiconductor layer can be obtained by laminating the first nitride semiconductor layer and the second nitride semiconductor layer. In addition, the second substrate and the second nitride semiconductor layer can be separated without damaging the nitride semiconductor layer with heat. Thereby, deterioration of device characteristics can be prevented. In addition, since the second substrate and the second nitride semiconductor layer can be separated without melting, unevenness is not generated on the surface of the second nitride semiconductor layer after separation. Furthermore, since it is not necessary to polish the second substrate, a nitride semiconductor layer can be obtained in a short time. Therefore, a nitride semiconductor layer can be obtained in a short time without deteriorating device characteristics.

  Preferably, in the method for manufacturing a semiconductor light emitting device according to another aspect of the present invention, a convex portion is formed on the surface of the first nitride semiconductor layer in the step of forming the first nitride semiconductor layer. A step of forming a recess having a size capable of accommodating the protrusion on the surface of the second nitride semiconductor layer corresponding to the protrusion is further provided.

  Thereby, when forming the nitride semiconductor layer, a convex part may be formed on the surface. When the convex portion is formed on the surface of the first nitride semiconductor layer, a gap may be formed between the first nitride semiconductor layer and the second nitride semiconductor layer in the bonding step, and the bonding may not be performed well. It is very difficult to planarize the surface of the nitride semiconductor layer by selectively polishing the convex portions. Therefore, by forming a recess in the surface of the second nitride semiconductor layer, the first nitride semiconductor layer and the second nitride semiconductor layer can be bonded together without a gap.

  Note that the surface of the second nitride semiconductor layer corresponding to the convex portion is the second nitride at a position facing the convex portion when the main surface of the first substrate and the main surface of the second substrate are opposed to each other. It means the surface of the physical semiconductor layer.

  In the method for manufacturing a semiconductor light emitting device according to another aspect of the present invention, preferably, in the separation step, an etching solution used for wet etching is made to reach the lift-off layer through the recess.

  Thereby, the etching solution can be directly introduced into the main surface of the lift-off layer through the recess, and the time required for etching the lift-off layer can be shortened.

  Preferably, in the method for manufacturing a semiconductor light emitting device according to another aspect of the present invention, the bonding step includes first nitriding while applying pressure in a state where the first substrate and the second substrate are exposed to a nitrogen plasma atmosphere in a reduced pressure state. A step of bonding the physical semiconductor layer and the second nitride semiconductor layer.

  Thereby, the first nitride semiconductor layer and the second nitride semiconductor layer are activated by the nitrogen plasma, and the first nitride semiconductor layer and the second nitride semiconductor layer can be joined only by applying pressure.

  In the method for manufacturing a semiconductor light emitting device according to another aspect of the present invention, preferably, the bonding step includes performing the first nitriding at a temperature not lower than a temperature at which the first nitride semiconductor layer and the second nitride semiconductor layer are melted at 80 ° C. or higher. This is performed in a state in which the physical semiconductor layer and the second nitride semiconductor layer are heated. Since the diffusion of the first nitride semiconductor layer and the second nitride semiconductor layer is promoted by heating to 80 ° C. or higher, the first nitride semiconductor layer and the second nitride semiconductor layer can be easily joined.

  According to the method for manufacturing a semiconductor light emitting element of the present invention, a nitride semiconductor layer can be obtained in a short time without deteriorating device characteristics.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a cross-sectional view showing the structure of the semiconductor light emitting device in the first embodiment of the present invention. FIG. 2 is a plan view of FIG. Referring to FIGS. 1 and 2, a surface emitting semiconductor laser as a semiconductor light emitting device of the present embodiment includes a substrate 1, a buffer layer 2, an n-type cladding layer 3, n-type GaN layers 4 and 18, and The light emitting layer 17, the cap layer 16, the p-type cladding layer 15, the p-type contact layer 14, the p-type electrode 31, and the n-type electrode 32 are provided.

  On the main surface 1a of the substrate 1, the buffer layer 2, the n-type cladding layer 3, the n-type GaN layer 4, the n-type GaN layer 18, the light emitting layer 17, the cap layer 16, the p-type cladding layer 15, and the p-type contact layer 14 Are stacked in this order. In each of the p-type contact layer 14, the p-type cladding layer 15, the cap layer 16, the light emitting layer 17, and the n-type GaN layer 18, a groove 20 (concave portion) reaching the n-type GaN layer 4 is formed. As shown in FIG. 2 in particular, the grooves 20 are formed in a matrix shape in plan view. That is, each of the p-type contact layer 14, the p-type cladding layer 15, the cap layer 16, the light emitting layer 17, and the n-type GaN layer 18 is separated in an island shape by the groove 20. Further, pits 5 (convex portions) are formed on the surface of the n-type GaN layer 4 exposed by the grooves 20. The pit 5 is formed at a position corresponding to each lattice point of the groove 20 and is accommodated in the groove 20. The pit 5 has, for example, a hexagonal pyramid shape.

  Further, a plurality of holes (not shown) are provided on the surface of the n-type GaN layer 4 so as to form a square lattice, and a diffraction grating point is constituted by each of the plurality of holes. Each hole is provided as a cylindrical or polygonal column shaped space. As a result, the n-type GaN layer 4 functions not only as an n-type guide layer but also as a photonic crystal layer.

  Each of the p-type electrodes 31 is formed so as to be in contact with each of the island-shaped p-type contact layers 14 separated by the grooves 20. The p-type electrode 31 is formed in, for example, a rectangular planar shape. An n-type electrode 32 is formed so as to be in contact with the main surface 1b of the substrate 1 opposite to the main surface 1a. N-type electrode 32 is formed, for example, so as to cover the entire main surface 1b.

  The substrate 1 is made of, for example, GaN, the buffer layer 2 is made of, for example, LT (Low Temperature) -GaN, and the n-type cladding layer 3 is made of, for example, n-type AlGaN. The light emitting layer 17 is made of, for example, an InGaN / GaN multiple quantum well, and the cap layer 16 is made of, for example, undoped GaN. Furthermore, the p-type cladding layer 15 is made of, for example, p-type AlGaN, and the p-type contact layer 14 is made of, for example, p-type GaN.

  Note that the surface emitting semiconductor laser of the present embodiment may further include layers other than those described above. For example, an n-type GaN layer or an InGaN layer as a strain suppression layer may be formed between the buffer layer 2 and the n-type cladding layer 3. Further, a p-type AlGaN layer as a block layer, a p-type GaN layer as a p-type guide layer, or the like may be formed between the cap layer 16 and the p-type cladding layer 15.

  Next, a light emitting method of the surface emitting semiconductor laser in the present embodiment will be described. When a positive voltage is applied to the p-type electrode 31, holes are injected from the p-type cladding layer 15 to the light emitting layer 17, and electrons are injected from the n-type cladding layer 3 to the light emitting layer 17. When holes and electrons (carriers) are injected into the light emitting layer 17, carrier recombination occurs and light is generated. The wavelength of the generated light is defined by the band gap of the semiconductor layer included in the light emitting layer 17.

  Light generated in the light-emitting layer 17 is confined in the light-emitting layer 17 by the n-type cladding layer 3 and the p-type cladding layer 15, but a part of the light is evanescent light as the n-type GaN layer 4 that is a photonic crystal layer. To reach. When the wavelength of the evanescent light reaching the n-type GaN layer 4 matches the predetermined periodic structure of the n-type GaN layer 4, the light repeats diffraction at the wavelength corresponding to the period, and the standing wave is Occurs and the phase condition is defined. The light whose phase is defined by the n-type GaN layer 4 is fed back to the light in the light emitting layer 17 and also generates a standing wave. This standing wave satisfies the wavelength and phase conditions of light defined in the n-type GaN layer 4.

  Such a phenomenon can occur in the region around the p-type electrode 31 and in the vicinity thereof, since the light emitting layer 17 and the n-type GaN layer 4 are two-dimensionally spread. When a sufficient amount of light is accumulated in this state, light having a uniform wavelength and phase condition is stimulated and emitted from a direction perpendicular to the main surface 1a of the substrate 1 (upward in FIG. 1).

  Next, a method for manufacturing the surface emitting semiconductor laser according to the present embodiment will be described with reference to FIGS. 4 is a plan view of FIG. 3, and FIG. 7 is a plan view of FIG.

  3 and 4, first, a substrate 1 (first substrate) made of, for example, GaN is prepared. The substrate 1 made of GaN is obtained, for example, by forming a GaN layer on a GaAs substrate by the MOVPE method and then cutting the GaN layer from the GaAs substrate.

  Subsequently, a nitride semiconductor layer (first nitride semiconductor) composed of each of the buffer layer 2, the n-type cladding layer 3, and the n-type GaN layer 4 is formed using, for example, a MOCVD (Metal-organic chemical vapor deposition) method. Layer) is epitaxially grown on the main surface 1a of the substrate 1 in this order. Thereafter, each of a plurality of holes 6 (FIG. 4) is opened on the surface of the n-type GaN layer 4. Each of the plurality of holes 6 is formed to constitute a square lattice, for example.

  Here, in particular, among the substrates 1 made of GaN, there are those manufactured by an epitaxial lateral over growth method. In such a substrate 1, a mask having a predetermined shape (for example, a mask made of SiOx) is disposed on a base substrate made of a material different from GaN, and a GaN layer is vapor-phased on the base substrate on which no mask is formed. It is formed by a growth method, and is produced by slicing and polishing a GaN layer into a thin plate shape. When the substrate 1 is manufactured, dislocations can be concentrated at any position on the substrate 1 depending on the position where the mask is disposed. When a layer is formed on the substrate 1 after the substrate 1 is manufactured, a depression is formed in the layer immediately above the dislocation concentration region of the substrate 1, and pits are generated in the periphery thereof. That is, the pit generation position can be controlled by the position where the mask formed on the base substrate is arranged. In FIG. 3, pits 5 are generated on the surface of the n-type GaN layer 4. In particular, as shown in FIG. 4, the pits 5 are generated at equal intervals, for example, at positions corresponding to lattice points, and the height thereof is, for example, several tens of nm.

  Referring to FIG. 5, next, substrate 11 (second substrate, substrate) made of sapphire, for example, is prepared separately from substrate 1. Then, the buffer layer 12 and the lift-off layer 13 are epitaxially grown on the main surface 11a of the substrate 11 in this order using, for example, MBE (Molecular Beam Epitaxy). Subsequently, the nitride semiconductor layer (second nitride semiconductor layer) constituted by each of the p-type contact layer 14, the p-type cladding layer 15, the cap layer 16, the light emitting layer 17, and the n-type GaN layer 18 is removed from the lift-off layer 13. Epitaxial growth is performed in this order. The buffer layer 12 is formed to alleviate the difference in lattice constant between the substrate 11 and the upper layer. The lift-off layer 13 is made of a crystal of a material such as GaN, AlN, InN, or GaMnN or a mixed crystal containing crystals. Since these substances have a lattice constant close to that of the nitride semiconductor layer, defects in the nitride semiconductor layer and internal stress in the nitride semiconductor layer can be suppressed.

  Next, referring to FIGS. 6 and 7, the trench 20 (which reaches the lift-off layer 13 in each of the n-type GaN layer 18, the light emitting layer 17, the cap layer 16, the p-type cladding layer 15, and the p-type contact layer 14). Introductory part, concave part) are formed. As shown in FIG. 7 in particular, the grooves 20 are formed in a matrix shape, for example, in plan view, and are formed so as to reach the end face S of the n-type GaN layer 18 or the like. As will be described later, the position of the groove 20 is defined so as to accommodate the pit 5. The groove 20 has a width of about 100 μm, for example. The groove 20 is preferably formed using a method such as dicing, dry etching, or laser irradiation. Thereby, the introduction part can be easily formed in a short time.

  Referring to FIG. 8, next, n-type GaN layer 4 and n-type GaN layer 18 are bonded together with main surface 1a of substrate 1 and main surface 11a of substrate 11 facing each other. When the n-type GaN layer 4 and the n-type GaN layer 18 are bonded together, the n-type GaN layer 4 and the n-type GaN are applied with pressure while the substrate 1 and the substrate 11 are exposed to a nitrogen plasma atmosphere under reduced pressure. It is preferable to bond the layer 18 together. Thereby, the n-type GaN layer 4 and the n-type GaN layer 18 are activated by the nitrogen plasma. Further, when the n-type GaN layer 4 and the n-type GaN layer 18 are bonded together, the n-type GaN layer 4 and the n-type GaN layer 18 are heated to a temperature not lower than the temperature at which the n-type GaN layer melts at 80 ° C. or more. You may paste together in a state. Thereby, diffusion of the n-type GaN layer 4 and the n-type GaN layer is promoted, so that the n-type GaN layer 4 and the n-type GaN layer 18 are easily joined. Further, these two bonding methods may be combined.

  Here, when the main surface 1a of the substrate 1 and the main surface 11a of the substrate 11 are opposed to each other, the lattice points of the matrix shape of the grooves 20 come to positions facing the pits 5 (see FIG. 2). Is formed. As a result, the pits 5 are accommodated in the grooves 20 in a state where the n-type GaN layer 4 and the n-type GaN layer 18 are bonded together, and the n-type GaN layer 4 and the n-type GaN layer 18 are not spaced apart from each other. Can be pasted together.

  Referring to FIG. 9, next, the lift-off layer 13 is wet etched. Thereby, the substrate 11 and the buffer layer 12 are separated from the p-type contact layer 14. The wet etching of the lift-off layer 13 is performed using an etching solution such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, dichromic acid, potassium hydroxide, or sodium hydroxide while applying an electric field to the etching solution.

  Here, the etchant used for wet etching reaches the lift-off layer 13 from the end face S of the nitride semiconductor layer through the groove 20 as shown by the arrows in the drawing, and etches the lift-off layer 13. By forming the groove 20, the etching solution can be directly introduced into the main surface of the lift-off layer 13, and the time required for etching the lift-off layer can be shortened.

  Referring to FIGS. 1 and 2, thereafter, p-type electrode 31 is formed on each of island-shaped p-type contact layers 14, and n-type electrode 32 is formed on main surface 1 b of substrate 1. Through the above steps, the surface emitting semiconductor laser of the present embodiment is completed.

  The surface emitting semiconductor laser manufacturing method of the present embodiment includes a step of forming the lift-off layer 13 on the substrate 11, a step of forming a nitride semiconductor layer including the light-emitting layer 17 on the lift-off layer 13, and the lift-off layer 13. And a separation step of separating the substrate 11 and the nitride semiconductor layer by wet etching.

  Further, the semiconductor laser manufacturing method of the present embodiment includes a step of forming the first nitride semiconductor layer on the main surface 1 a of the substrate 1 and a step of forming the lift-off layer 13 on the main surface 11 a of the substrate 11. The step of forming the second nitride semiconductor layer including the light emitting layer 17 on the lift-off layer 13 and the first nitride semiconductor layer with the main surface 1a of the substrate 1 and the main surface 11a of the substrate 11 facing each other A bonding step of bonding the second nitride semiconductor layer and a separation step of separating the substrate 11 and the second nitride semiconductor layer by wet etching the lift-off layer 13 are provided.

  According to the manufacturing method of the semiconductor laser of the present embodiment, the substrate 11 and the nitride semiconductor layer (second nitride semiconductor layer) can be separated without causing damage to the nitride semiconductor layer due to heat. Thereby, deterioration of device characteristics can be prevented. Further, since the substrate 11 and the nitride semiconductor layer (second nitride semiconductor layer) can be separated without melting, the surface of the nitride semiconductor layer (second nitride semiconductor layer) after separation is uneven. Don't make it happen. Furthermore, since it is not necessary to polish the substrate 11, a nitride semiconductor layer can be obtained in a short time. Therefore, a nitride semiconductor layer can be obtained in a short time without deteriorating device characteristics.

(Embodiment 2)
In the first embodiment, the case where the semiconductor light emitting element of the present invention is a surface emitting semiconductor laser has been described. However, the semiconductor light emitting device of the present invention may be a surface emitting semiconductor laser or an LED (Light Emitting Diode). In this embodiment, the case where the semiconductor light emitting element of the present invention is an LED will be described.

  FIG. 10 is a cross-sectional view showing the structure of the semiconductor light emitting device in the second embodiment of the present invention. FIG. 11 is a plan view of FIG. Referring to FIGS. 10 and 11, the LED as the semiconductor light emitting device of the present embodiment includes a substrate 101, a buffer layer 102, n-type GaN layers 103 and 116, a light emitting layer 115, and a p-type contact layer. 114, a p-type electrode 131, and an n-type electrode 132.

  On the main surface 101a of the substrate 1, a buffer layer 102, an n-type GaN layer 103, an n-type GaN layer 116, a light emitting layer 115, and a p-type contact layer 114 are laminated in this order. In each of the p-type contact layer 114, the light emitting layer 115, and the n-type GaN layer 116, a groove 120 (concave portion) reaching the n-type GaN layer 103 is formed. As shown in FIG. 11 in particular, the grooves 120 are formed in a matrix shape in plan view. That is, each of the p-type contact layer 114, the light emitting layer 115, and the n-type GaN layer 116 is separated in an island shape by the groove 120. Also, pits 105 (convex portions) are formed on the surface of the n-type GaN layer 103 exposed by the grooves 120. The pit 105 is formed at a position corresponding to each lattice point of the groove 120 and is accommodated in the groove 120. The pit 105 has, for example, a hexagonal pyramid shape.

  Each of the p-type electrodes 131 is formed so as to be in contact with each of the island-shaped p-type contact layers 114 separated by the grooves 120. The p-type electrode 131 is formed in, for example, a rectangular planar shape. In addition, n-type electrode 132 is formed so as to be in contact with main surface 101b of substrate 101 opposite to main surface 101a. N-type electrode 132 is formed, for example, so as to cover the entire main surface 101b.

  The substrate 101 is made of, for example, GaN, the buffer layer 102 is made of, for example, LT-GaN, the light emitting layer 115 is made of, for example, an InGaN / GaN multiple quantum well, and the p-type contact layer 114 is made of, for example, p-type GaN. It has become more.

  The LED of the present embodiment may further include layers other than those described above. For example, an undoped GaN layer as a cap layer or a p-type AlGaN layer as a block layer may be formed between the light emitting layer 115 and the p-type contact layer 114.

  Next, the light emission method of LED in this Embodiment is demonstrated. When a positive voltage is applied to the p-type electrode 31, holes and electrons (carriers) are injected into the light emitting layer 115, recombination of carriers occurs, and light is generated. The wavelength of the generated light is defined by the band gap of the semiconductor layer included in the light emitting layer 115.

  Next, the manufacturing method of LED in this Embodiment is demonstrated using FIGS.

  Referring to FIG. 12, first, a substrate 101 (first substrate) made of, for example, GaN is prepared. Then, for example, a nitride semiconductor layer (first nitride semiconductor layer) constituted by each of the buffer layer 102 and the n-type GaN layer 103 is epitaxially grown on the main surface 101a of the substrate 101 in this order using MOCVD. . As a result, pits 105 are generated on the surface of the n-type GaN layer 103. The pits 105 are generated at equal intervals, for example, at positions corresponding to lattice points.

  Referring to FIG. 13, next, a substrate 111 (second substrate, substrate) made of sapphire, for example, is prepared separately from the substrate 101. Then, for example, using the MBE method, the buffer layer 112 and the lift-off layer 113 are epitaxially grown on the main surface 111a of the substrate 111 in this order. Subsequently, a nitride semiconductor layer (second nitride semiconductor layer) constituted by each of the p-type contact layer 114, the light emitting layer 115, and the n-type GaN layer 116 is epitaxially grown on the lift-off layer 113 in this order.

  Referring to FIG. 14, next, a groove 120 (introduction portion, recess) reaching the lift-off layer 113 is formed in each of the n-type GaN layer 116, the light emitting layer 115, and the p-type contact layer 114. For example, the trench 120 is formed in a matrix shape in plan view, and is formed so as to reach the end face of the n-type GaN layer 116 or the like. The position of the groove 120 is defined so that the pit 5 can be accommodated.

  Referring to FIG. 15, next, n-type GaN layer 103 and n-type GaN layer 116 are bonded together with main surface 101a of substrate 101 and main surface 111a of substrate 111 facing each other. The pit 105 is accommodated in the groove 120 in a state where the n-type GaN layer 103 and the n-type GaN layer 116 are bonded together. Subsequently, the lift-off layer 113 is wet etched to separate the substrate 111 and the buffer layer 112 from the p-type contact layer 114.

  Referring to FIGS. 10 and 11, thereafter, p-type electrode 131 is formed on each of the island-shaped p-type contact layers 114, and n-type electrode 132 is formed on main surface 101 b of substrate 101. Through the above steps, the LED of the present embodiment is completed.

  According to the LED manufacturing method of the present embodiment, the same effects as those of the surface emitting semiconductor laser manufacturing method of the first embodiment can be obtained.

(Embodiment 3)
In the first and second embodiments, the case where the stripe-shaped groove 20 is formed in the nitride semiconductor layer has been described. However, the present invention is not limited to the case of forming the groove 20 having such a shape, and is at least a portion for allowing an etching solution to be introduced into the lift-off layer from the outside, or a size capable of accommodating the convex portion. It suffices if a recess is formed.

  FIG. 16 is a cross-sectional view showing a method for manufacturing a semiconductor light emitting element in the third embodiment of the present invention. FIG. 17 is a plan view of FIG. Referring to FIGS. 16 and 17, in the LED manufacturing method according to the present embodiment, the n-type GaN layer is obtained after the manufacturing process similar to the manufacturing process of the second embodiment shown in FIGS. 116, a light emitting layer 115, a p-type contact layer 114, a lift-off layer 113, a buffer layer 112, and a plurality of holes 121 are formed so as to penetrate the substrate 111. Each of the plurality of holes 121 is formed at a position corresponding to the pit 5 in plan view. Thereafter, the LED of the present embodiment is completed through the same manufacturing process as that of the second embodiment shown in FIG.

  According to the LED manufacturing method of the present embodiment, the same effects as those of the surface emitting semiconductor laser manufacturing method of the first embodiment can be obtained. In addition, when the lift-off layer 113 is etched, an etchant can be introduced from the main surface 111 b of the substrate 111 into the lift-off layer 113 through the hole 121. Further, the flow rate of the etching solution can be controlled in accordance with the hole diameter of the hole 121.

It should be noted that the manufacturing method of the present embodiment can be appropriately combined with the manufacturing method of Embodiment 1, for example. In addition, as a method of forming the introduction portion, a mask layer made of, for example, SiO ₂ or SiN _x is formed at a position to be the introduction portion on the second substrate, in addition to forming a groove or a hole in the nitride semiconductor layer. In addition, a method of selectively growing a nitride semiconductor layer only in a portion where there is no mask layer on the second substrate is also mentioned.

  In this example, a semiconductor laser was manufactured using the same manufacturing method as in the first embodiment. Specifically, a semiconductor laser was manufactured by the following method.

A GaAs (111) substrate having a diameter of 2 inches was prepared. An SiO ₂ film was formed on the GaAs substrate, and openings having an opening diameter of 10 μm were formed at a pitch of 250 μm in the SiO ₂ film by photolithography. Thereby, a mask layer made of SiO ₂ was formed. Next, a GaN layer was formed to a thickness of 3 mm on the GaAs substrate by using the MOVPE method, and then the GaN layer was cut to a thickness of 500 μm by using a slicer, and the surface of the GaN layer was polished to give a mirror surface. In this way, a GaN (0001) substrate was prepared. Next, each of the LT-GaN layer, the n-type GaN layer, the n-type InGaN layer, the n-type AlGaN layer, and the n-type GaN layer was formed in this order on the GaN substrate by using the MOVPE method. As a result, recesses with a depth of 200 nm at a pitch of 250 μm and pits with a height of 50 nm were formed on the surface of the n-type GaN layer. Next, a plurality of holes having a depth of 120 nm were formed on the surface of the n-type GaN layer using a resist having a 160 nm pitch and an opening diameter of 90 nm.

  On the other hand, a sapphire substrate having a diameter of 2 inches was prepared separately from the GaN substrate. Next, using MBE method, LT-GaN layer, GaMnN layer, p-type GaN layer, p-type AlGaN layer, p-type GaN layer, p-type AlGaN layer, undoped GaN layer, InGaN / GaN multiple quantum well layer, and Each of the n-type GaN layers was formed on the sapphire substrate in this order. Then, a resist mask having a stripe-shaped opening having a width of 30 μm at a pitch of 250 μm was formed and dry-etched to form a groove having a depth reaching from the n-type GaN layer surface to the GaMnN layer.

Next, the n-type GaN layer on the GaN substrate and the n-type GaN layer on the sapphire substrate were overlapped so that the pits on the GaN substrate and the lattice points of the striped grooves on the sapphire substrate faced each other. In this state, a GaN substrate and a sapphire substrate were introduced into a vacuum furnace. Then, the inside of the vacuum furnace was put into a nitrogen atmosphere, heated to a temperature of 600 ° C. while generating plasma, and a pressure of 1 kgf / cm ² (9.8 × 10 ⁴ Pa) was applied and held for 30 minutes. Thereby, n-type GaN layers were bonded together. After confirming the bonding, the GaN substrate and the sapphire substrate were immersed in a sulfuric acid solution while applying an electric field. As a result, the GaMnN layer was dissolved and the sapphire substrate was peeled off. Thereafter, electrodes were respectively formed on the GaN substrate and the p-type GaN layer to obtain a surface emitting semiconductor laser.

  When the surface-emitting semiconductor laser thus obtained was energized, surface emission was confirmed.

  In this example, an LED was manufactured using the same manufacturing method as in the second embodiment. Specifically, an LED was manufactured by the following method.

A GaAs (111) substrate having a diameter of 2 inches was prepared. An SiN _x film was formed on this GaAs substrate, and openings with an opening diameter of 60 μm were formed at a pitch of 400 μm in the SiN _x film by photolithography. Thereby, a mask layer made of SiN _x was formed. Next, a GaN layer was formed to a thickness of 3 mm on the GaAs substrate by using the MOVPE method, and then the GaN layer was cut to a thickness of 300 μm by using a slicer, and the surface of the GaN layer was polished to give a mirror surface. In this way, a GaN (0001) substrate was prepared. Next, each of the LT-GaN layer and the n-type GaN layer was formed on the GaN substrate in this order by using the MOVPE method. As a result, pits having a depth of 300 nm at a pitch of 400 μm and pits having a height of 50 nm were formed on the surface of the n-type GaN layer.

  On the other hand, a sapphire substrate having a diameter of 2 inches was prepared separately from the GaN substrate. Next, an LT-GaN layer and a GaMnN layer were formed using the MBE method. Furthermore, each of a p-type GaN layer, a p-type AlGaN layer, an undoped GaN layer, an InGaN / GaN multiple quantum well layer, and an n-type GaN layer was formed on the GaMnN layer in this order by using the MOVPE method. Then, using a diamond blade, stripe-like grooves having a width of 400 μm and a width of 50 μm were formed with a depth reaching the GaMnN layer.

Next, the n-type GaN layer on the GaN substrate and the n-type GaN layer on the sapphire substrate were overlapped so that the pits on the GaN substrate and the lattice points of the striped grooves on the sapphire substrate faced each other. In this state, a GaN substrate and a sapphire substrate were introduced into a vacuum furnace. Then, the inside of the vacuum furnace was put into a nitrogen atmosphere, heated to a temperature of 400 ° C. while generating plasma, and a pressure of 1 kgf / cm ² (9.8 × 10 ⁴ Pa) was applied and held for 30 minutes. Thereby, n-type GaN layers were bonded together. After confirming the bonding, the GaN substrate and the sapphire substrate were immersed in a sulfuric acid solution while applying an electric field. As a result, the GaMnN layer was dissolved and the sapphire substrate was peeled off. Thereafter, electrodes were formed on the GaN substrate and the p-type GaN layer, respectively, to obtain an LED.

  When the LED thus obtained was divided into grooves using a diamond blade to form a chip and energized, light emission was confirmed.

  In this example, an LED was manufactured using the same manufacturing method as in the third embodiment. Specifically, an LED was manufactured by the following method.

A GaAs (111) substrate having a diameter of 2 inches was prepared. An SiO _x film was formed on the GaAs substrate, and openings having an opening diameter of 60 μm were formed at a pitch of 400 μm in the SiO _x film by photolithography. Thereby, a mask layer made of SiO _x was formed. Next, a GaN layer was formed to a thickness of 3 mm on a GaAs substrate by using the MOVPE method, and then the GaN layer was cut to a thickness of 400 μm using a slicer, and the surface of the GaN layer was polished to give a mirror surface. In this way, a GaN (0001) substrate was prepared. Next, each of the LT-GaN layer and the n-type GaN layer was formed on the GaN substrate in this order by using the MOVPE method. As a result, pits having a depth of 300 nm at a pitch of 400 μm and pits having a height of 50 nm were formed on the surface of the n-type GaN layer.

  On the other hand, a sapphire substrate having a diameter of 2 inches was prepared separately from the GaN substrate. Next, an LT-GaN layer and a GaMnN layer were formed using the MBE method. Furthermore, each of a p-type GaN layer, a p-type AlGaN layer, an undoped GaN layer, an InGaN / GaN multiple quantum well layer, and an n-type GaN layer was formed on the GaMnN layer in this order by using the MOVPE method. Then, using an excimer laser, a plurality of holes penetrating from the n-type GaN layer to the sapphire substrate were formed at a pitch of 400 μm.

Next, in a state where the n-type GaN layer on the GaN substrate and the n-type GaN layer on the sapphire substrate are overlapped so that the pits on the GaN substrate and the holes in the sapphire substrate face each other, the GaN substrate and the sapphire The substrate was introduced into a vacuum furnace. Then, the inside of the vacuum furnace was put into a nitrogen atmosphere, heated to a temperature of 700 ° C. while generating plasma, and a pressure of 3 kgf / cm ² (29.4 × 10 ⁴ Pa) was applied and held for 60 minutes. Thereby, n-type GaN layers were bonded together. After confirming the bonding, the GaN substrate and the sapphire substrate were immersed in a sulfuric acid solution while applying an electric field. As a result, the GaMnN layer was dissolved and the sapphire substrate was peeled off. Thereafter, electrodes were formed on the GaN substrate and the p-type GaN layer, respectively, to obtain an LED.

  When the LED thus obtained was divided into chips using a scribe device and a breaker device and energized, light emission was confirmed.

  The embodiments and examples disclosed above are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and is intended to include all modifications and variations within the meaning and scope equivalent to the scope of claims. .

  The present invention is suitable for a method for manufacturing a semiconductor light-emitting device including a nitride semiconductor layer containing GaN.

It is sectional drawing which shows the structure of the semiconductor light-emitting device in Embodiment 1 of this invention. It is a top view which shows the structure of the semiconductor light-emitting device in Embodiment 1 of this invention. It is sectional drawing which shows the 1st process of the manufacturing method of the semiconductor light-emitting device in Embodiment 1 of this invention. It is a top view which shows the 1st process of the manufacturing method of the semiconductor light-emitting device in Embodiment 1 of this invention. It is sectional drawing which shows the 2nd process of the manufacturing method of the semiconductor light-emitting device in Embodiment 1 of this invention. It is sectional drawing which shows the 3rd process of the manufacturing method of the semiconductor light-emitting device in Embodiment 1 of this invention. It is a top view which shows the 3rd process of the manufacturing method of the semiconductor light-emitting device in Embodiment 1 of this invention. It is sectional drawing which shows the 4th process of the manufacturing method of the semiconductor light-emitting device in Embodiment 1 of this invention. It is sectional drawing which shows the 5th process of the manufacturing method of the semiconductor light-emitting device in Embodiment 1 of this invention. It is sectional drawing which shows the structure of the semiconductor light-emitting device in Embodiment 2 of this invention. It is a top view which shows the structure of the semiconductor light-emitting device in Embodiment 2 of this invention. It is sectional drawing which shows the 1st process of the manufacturing method of the semiconductor light-emitting device in Embodiment 2 of this invention. It is sectional drawing which shows the 2nd process of the manufacturing method of the semiconductor light-emitting device in Embodiment 2 of this invention. It is sectional drawing which shows the 3rd process of the manufacturing method of the semiconductor light-emitting device in Embodiment 2 of this invention. It is sectional drawing which shows the 4th process of the manufacturing method of the semiconductor light-emitting device in Embodiment 2 of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor light-emitting device in Embodiment 3 of this invention. It is a top view which shows the manufacturing method of the semiconductor light-emitting device in Embodiment 3 of this invention.

Explanation of symbols

  1, 11, 101, 111 substrate, 1a, 1b, 11a, 101a, 101b, 111a, 111b substrate main surface, 2, 12, 102, 112 buffer layer, 3 n-type cladding layer, 4, 18, 103, 116 n-type GaN layer, 5,105 pits, 6,121 holes, 13,113 lift-off layer, 14,114 p-type contact layer, 15 p-type cladding layer, 16 cap layer, 17,115 light emitting layer, 20,120 groove, 31, 131 p-type electrode, 32, 132 n-type electrode.

Claims (12)

Forming a lift-off layer on the substrate;
Forming a nitride semiconductor layer including a light emitting layer on the lift-off layer;
A method for manufacturing a semiconductor light emitting device, comprising: a separation step of separating the substrate and the nitride semiconductor layer by performing wet etching on the lift-off layer.   2. The semiconductor light emitting device according to claim 1, further comprising an introduction part process for forming an introduction part for allowing an etchant used for the wet etching to reach the lift-off layer before the separation process. Manufacturing method.   The method for manufacturing a semiconductor light emitting device according to claim 2, wherein the introduction portion is a groove formed so as to reach an end face of the nitride semiconductor layer.   The method of manufacturing a semiconductor light emitting device according to claim 2, wherein the introduction part is a hole formed so as to penetrate the nitride semiconductor layer and the substrate.   5. The introduction portion is formed in the nitride semiconductor layer using any one of dicing, dry etching, and laser irradiation in the introduction portion step. 6. Manufacturing method of the semiconductor light-emitting device.   In the separation step, the lift-off layer is etched while applying an electric field to an etching solution containing at least one selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, dichromic acid, potassium hydroxide, and sodium hydroxide. A method for manufacturing a semiconductor light emitting device according to claim 1, wherein:   The semiconductor according to claim 1, wherein the lift-off layer is made of a crystal containing at least one selected from the group consisting of GaN, AlN, InN, and GaMnN, or a mixed crystal containing crystals. Manufacturing method of light emitting element. Forming a first nitride semiconductor layer on the main surface of the first substrate;
Forming a lift-off layer on the main surface of the second substrate;
Forming a second nitride semiconductor layer including a light emitting layer on the lift-off layer;
A bonding step of bonding the first nitride semiconductor layer and the second nitride semiconductor layer with the main surface of the first substrate and the main surface of the second substrate facing each other;
A method for manufacturing a semiconductor light emitting device, comprising: a separation step of separating the second substrate and the second nitride semiconductor layer by wet etching the lift-off layer. In the step of forming the first nitride semiconductor layer, a convex portion is formed on the surface of the first nitride semiconductor layer,
The method of manufacturing a semiconductor light emitting element according to claim 8, further comprising forming a recess having a size capable of accommodating the protrusion on the surface of the second nitride semiconductor layer corresponding to the protrusion. Method.   10. The method of manufacturing a semiconductor light emitting element according to claim 9, wherein in the separation step, an etching solution used for the wet etching is allowed to reach the lift-off layer through the recess.   In the bonding step, the first nitride semiconductor layer and the second nitride semiconductor layer are bonded while applying pressure in a state where the first substrate and the second substrate are exposed to a nitrogen plasma atmosphere in a reduced pressure state. The method for manufacturing a semiconductor light-emitting element according to claim 8, further comprising a step of combining.   In the bonding step, the first nitride semiconductor layer and the second nitride semiconductor layer are heated to a temperature of 80 ° C. or higher and lower than a temperature at which the first nitride semiconductor layer and the second nitride semiconductor layer are melted. The method for manufacturing a semiconductor light-emitting element according to claim 8, wherein the method is performed in a state.

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