JP2006165051A - Semiconductor light emitting element and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for easily obtaining a semiconductor light emitting element including high precision photonic crystal and also provide a semiconductor light emitting element manufactured with the same manufacturing method. <P>SOLUTION: The method for manufacturing an element including the structures 3, 5 having the photonic crystal effect comprises the steps of forming a GaN system semiconductor layer 3 including a crystal inverting region 4 and removing the crystal inverting region 4 with the wet etching process. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Among GaN-based semiconductor light-emitting elements, a semiconductor laser (LD), in particular, has been developed as a light source for a high-density recording medium because its emission wavelength is around 400 nm and is shorter than that of a conventional semiconductor laser. Most of the forms are edge-emitting types, and in recent years, the output has been increasing.

  On the other hand, surface-emitting types are also being developed. In the vertical resonator structure, there is a problem that cracks are generated in the middle of forming a mirror for obtaining reflection due to mismatch of lattice constant between sapphire substrate and GaN which are usually used. For this reason, sufficient light emission has not yet been made.

  On the other hand, in recent years, a technique for forming a surface emitting laser using a photonic crystal structure has been proposed for InP-based materials (Non-Patent Document 1). Light in a wavelength region corresponding to the optical band gap cannot propagate through the optical periodic structure. For this reason, if light corresponding to the optical band gap is introduced into the light guide path in which the periodicity of the optical periodic structure has been lost, the light propagates through the light guide path without leaking into the surrounding periodic region. To do. In view of this, a surface light-emitting element manufactured by utilizing the fact that standing waves are generated by light receiving multidirectional in-plane distributed feedback at the band edge in the photonic band structure has been proposed.

  GaN-based semiconductor lasers cannot use wet etching to form a ridge structure, which is essential for the structure of edge-emitting lasers, due to the high chemical stability of GaN. Reactive ion etching (RIE) ) Method is applied (Non-Patent Document 2). By performing drilling using RIE, a photonic crystal can be produced with high efficiency.

  Since the above-mentioned photonic crystal has a periodic structure in which portions having different refractive indexes are alternately arranged as an optical medium, it is necessary to form a periodic structure of two or more different optical media in production. In this case, when the light in the visible light range is targeted, the wavelength is in the sub-micron range, so the processing accuracy is also required to be sub-micron.

As the periodic structure of the optical periodic structure, for example, a structure of a semiconductor substrate in which high-density defect regions in which defects are concentrated in order to obtain a wide range of low-density defect regions in the production of a semiconductor substrate can be considered (patent) Reference 1). In this structure, the high density defect regions are arranged in the low density defect region, and the high and low refractive index regions are alternately arranged. In addition to the above, a method using wet etching is proposed among methods for increasing the crystal defect density of a semiconductor substrate (Patent Document 2). In this method, ion implantation is used to increase the crystal defect density. As a result, a periodic structure with high and low crystal defect density can be formed with high controllability.
JP 2003-183100 A Japanese Patent Laid-Open No. 10-233385 Hikaru Yokoyama, Susumu Noda "Two-dimensional photonic crystal surface emitting laser" Journal of Infrared Radiology, Vol. 12, No. 2003 2003 Thomas D. Happ, Alexander Markard, Martin Kamp, and Alfred Forchel, "Single-mode operation of coupled-cavity lasers based on two-dimensional photonic crystals", Applied Physics Letters, Vol. 79, No. 25, pp.4091- 4093

However, for example, in the method disclosed in Patent Document 1 described above, since there is no idea of arranging defect concentration regions in order to obtain an optical periodic structure, a photonic crystal having a submicron period intended for the visible light region is used. It cannot be obtained with high accuracy. Further, in the method disclosed in Patent Document 2, since the high-density defect region is formed by ion implantation, the number of steps is increased and the cost is increased. Moreover, although it has been shown that a material that increases the crystal defect density is attached, it is described that 10 ¹⁰ / cm ² or more, which is described as being locally etched even in an average crystal defect density region of about 10 ⁴ / cm ^2. There is a possibility that etch pits and the like are formed. Therefore, it is difficult to use this method for producing a photonic crystal.

  Further, in the method using RIE disclosed in Non-Patent Document 2, since RIE is performed in parallel with chemical reaction and physical removal processing, a damage layer caused by physical processing is formed on the processing surface. Is done. Since GaN-based semiconductors are stronger than GaAs and InP, those capable of laser oscillation are produced even if a ridge structure is formed by the RIE method. It has become. In addition, although the photonic crystal structure type surface emitting laser can solve the crack due to mismatch with the substrate, the method of forming the fine structure of the photonic crystal is the RIE method described above. The depth of the damaged layer may be several hundred nm, and the entire periodic structure may be damaged.

  An object of this invention is to provide the manufacturing method which can obtain easily the semiconductor light-emitting device containing the highly accurate photonic crystal excellent in crystallinity, and the semiconductor light-emitting device using the manufacturing method.

  The method for manufacturing a semiconductor light emitting device of the present invention is a method for manufacturing a device including a structure having a photonic crystal effect, the step of forming a GaN-based material layer including a crystal inversion region, and wet etching of the crystal inversion region. And removing it.

  With the above configuration, if the crystal inversion region is two-dimensionally arranged in the GaN-based material layer on the pattern mask, the refractive index of the GaN-based material and the air or other gas removed from the wet etching, etc. The refractive index in the vicinity of 1 is periodically arranged in a two-dimensional manner. For this reason, the photonic crystal effect can be expressed. The point of this method is that a crystal inversion region of a GaN-based material is formed on a pattern mask having a two-dimensional periodic pattern, and that the crystal inversion region is easily wet-etched. According to the above method, a highly accurate photonic effect can be easily obtained.

  Another method of manufacturing a semiconductor light emitting device of the present invention is a method of manufacturing a device including a structure having a photonic crystal effect, the step of forming a pattern mask of a material layer containing Si on a substrate, A step of epitaxially growing a GaN-based semiconductor layer so that a crystal inversion region is formed on at least a part of the pattern mask, a step of planarizing the epitaxially-grown GaN-based semiconductor layer, and a step of forming on the pattern mask And a step of removing the crystal inversion region with an alkaline solvent. Then, a step of preparing an active layer forming substrate different from the above substrate and epitaxially growing a plurality of semiconductor layers including the active layer on the active layer forming substrate, and flattening the upper surface of the semiconductor layer including the active layer And a step of bonding the substrate and the active layer forming substrate so that the surface of the flattened GaN-based semiconductor layer of the substrate and the flattened surface of the active layer forming substrate face each other. It is characterized by that.

  With the above structure, a layer having a photonic effect can be easily formed with high accuracy and integrated with a layer including an active layer. Therefore, a light-emitting element including a layer having a photonic effect can be easily made compact.

  The semiconductor light-emitting device of the present invention is a light-emitting device including a GaN-based semiconductor layer, having a two-dimensional periodic pattern mask, and a substance having a refractive index different from that of the GaN-based semiconductor layer is a GaN-based material on the pattern mask. The semiconductor layer is arranged to form a two-dimensional periodic array.

  The light-emitting element having the above structure is a semiconductor light-emitting element that includes a portion that exhibits a photonic effect that is easily manufactured with high accuracy.

  Another semiconductor light-emitting device of the present invention is a light-emitting device formed on a film-forming base layer, wherein the film-forming base layer is an epitaxially grown GaN-based semiconductor layer including crystal inversion regions arranged two-dimensionally. A GaN-based semiconductor layer epitaxially grown on the film-forming base layer and a substance having a refractive index different from that of the GaN-based semiconductor layer located on the crystal inversion region in the film-forming base layer It is arranged.

  According to the above structure, if a thick epitaxial layer including a crystal inversion region is formed on one pattern mask, a large number of base layers for film formation can be obtained, and a pattern mask is produced for each semiconductor light emitting device. There is no need to do. For this reason, the manufacturing efficiency of the semiconductor light emitting device can be greatly improved.

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

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing a configuration of a semiconductor laser element using a photonic crystal as an example of the semiconductor light emitting element in the first embodiment of the present invention. Referring to FIG. 1, a semiconductor laser device 10 includes, for example, a substrate 1, a pattern mask 2, photonic crystals 3, 5 as a two-dimensional diffraction grating, an n-type cladding layer 14, an active layer 15, A p-type cladding layer 16, an anode electrode 21, and a cathode electrode 22 are included.

  The substrate 1 is made of, for example, n-type GaN (gallium nitride). A pattern mask 2 having a two-dimensional periodicity is located on the surface 1 a of the substrate 1. Photonic crystals 3 and 5 are disposed on the substrate surface 1a. The photonic crystals 3 and 5 have a medium 3 having a first refractive index and a second refractive index portion 5 provided on the surface of the medium so as to form a two-dimensional diffraction grating. . The medium 3 having the first refractive index is, for example, an n-type GaN cladding layer (refractive index: 2.54) formed by epitaxial growth. Since the second refractive index portion 5 is a trace removed by wet etching, for example, it is a hole filled with air (refractive index: 1). The second refractive index portion 5 is a columnar (for example, columnar) space, and the lattice is formed on the surface of the medium 3 having the first refractive index so as to form, for example, a triangular lattice or a square lattice. Arranged at points.

  In addition, the case where the second refractive index portion 5 is filled with air has been described. However, a gas other than air may be filled, or a solid may be filled. In this case, a silicon nitride film (SiNx) or the like can be used as a material filled in the second refractive index portion 5, that is, a low refractive index dielectric material. When the difference in refractive index is thus increased, light can be confined in the medium 3 having the first refractive index.

  On the surface of the photonic crystals 3 and 5, an n-type cladding layer 14, an active layer 15 and a p-type cladding layer 16 are formed in this order.

The active layer 15 is made of a material that generates light by injecting carriers, and is composed of, for example, a multiple quantum well made of Al _x Ga _{1 -xy} In _y N (0 ≦ x, y ≦ 1, 0 ≦ x + y ≦ 1). It may be made of a single semiconductor material.

  The n-type cladding layer 14 is made of, for example, n-type GaN, and the p-type cladding layer 16 is made of, for example, p-type GaN. The n-type cladding layer 14 and the p-type cladding layer 16 function as conductive layers through which carriers to be given to the active layer 15 are conducted. For this reason, the n-type cladding layer 14 and the p-type cladding layer 16 are provided so as to sandwich the active layer 15. The n-type cladding layer 14 and the p-type cladding layer 16 both function as confinement layers that confine carriers (electrons and holes) in the active layer 15. That is, the n-type cladding layer 14, the active layer 15, and the p-type cladding layer 16 form a double heterojunction, and carriers contributing to light emission can be concentrated in the active layer 15.

  Further, the n-type cladding layer 14 may function as a blocking layer that blocks the entrance of holes into the photonic crystals 3 and 5. As a result, it is possible to prevent non-radiative recombination of electrons and holes in the photonic crystals 3 and 5. In particular, when the diffraction grating point 5 is made of air, non-radiative recombination is likely to occur on the surface of the diffraction grating point 5, so that the function as a block layer is important.

  An anode electrode 21 is formed on the surface of the p-type cladding layer 16 so as to be electrically connected to the p-type cladding layer 16, and a cathode electrode 22 is electrically connected to the substrate 1 on the back surface of the substrate 1. Is formed.

  A bonding wire (not shown) is electrically connected to the anode electrode 21.

  FIG. 2 is a plan view of the semiconductor light emitting device 10 shown in FIG. The semiconductor light emitting devices 10 shown in FIGS. 1 and 2 may be arranged in an array as shown in FIG.

  In the semiconductor light emitting device shown in FIG. 1, a standing wave is generated when light undergoes multidirectional in-plane distributed feedback at the photonic band edge of the photonic crystal structure. For this reason, for example, light is emitted upward (on the electrode 21 side). The semiconductor light emitting device of this embodiment is a surface light emitting type device.

  Next, a method for manufacturing the semiconductor light emitting element will be described including the principle part.

(Manufacturing principle)
FIG. 4 is a schematic diagram of the crystal structure of GaN. Ga planes and N planes are alternately arranged perpendicular to the c-axis of the wurtzite structure. The c-axis is also the growth direction, and a single crystal substrate, a highly oriented substrate, or an epitaxial layer tends to form a surface perpendicular to the c-axis. With respect to the c-axis direction, the bond between Ga and N is easily broken at the dotted line parts B ₁ and B ₂ shown in FIG. 4, so that the GaN substrate has, for example, the polarity of the Ga surface on its upper surface (front surface) 1a and the lower surface (back surface). ) 1b has N-plane polarity.

  FIG. 5 is a diagram showing a state in which the pattern mask 2 is formed on the substrate. FIG. 6 shows a state in which a GaN-based semiconductor layer is epitaxially grown thereon. Referring to FIG. 6, the present inventors epitaxially grow a GaN-based semiconductor layer on a substrate 1 (for example, a GaN (0001) substrate) on which a pattern mask 2 is selectively formed in an atmosphere into which a chlorine-based gas is introduced. It is found that the upper surface 3a of the portion of the GaN-based semiconductor layer 3 epitaxially grown in contact with the substrate 1 is a Ga surface and the upper surface 4a of the portion of the GaN-based semiconductor layer 4 in contact with the pattern mask 2 is an N-plane. It was. That is, the present inventors have found that the crystal inversion region 4 is generated in the GaN-based semiconductor layer on the pattern mask 2. As described above, the present invention has a great feature in that a two-dimensional periodic pattern is formed by utilizing the fact that the crystal inversion region 4 can be formed on the pattern mask 2.

  As a method for forming the GaN-based semiconductor layer, an organic metal CVD method, a CVD method, various vacuum deposition methods, or the like can be used.

  FIG. 7 is a diagram showing a flattened state in order to eliminate the surface uneven portion (removed portion) 17 in the epitaxial growth layers 3 and 4 shown in FIG. In FIG. 7, the surface is flattened by polishing, but any flattening method that is generally known as a method that does not damage the inside largely may be used.

  Next, the shape of the pattern mask will be described in detail. FIG. 8 is a plan view for showing the shape of the pattern mask 2 shown in FIG. Circular masks 2 are discretely arranged regularly (for example, a square lattice array) on the substrate surface 1a. FIG. 9 is a plan view showing a pattern of the crystal inversion region 4 formed on the pattern mask shown in FIG. The crystal inversion regions 4 having a diameter smaller than that of the mask circle are regularly arranged in the GaN-based semiconductor layer 3 in a square lattice shape, for example. The reason why the diameter of the crystal inversion region 4 is smaller than the diameter of the pattern mask 2 is that the GaN epitaxial growth layer 3 enters a little inside the edge of the mask as shown in FIG. The pattern mask 2 can be formed of a material containing Si, but when the GaN-based semiconductor layers 3 and 4 are epitaxially grown on the underlying substrate, the crystal inversion region 4 of the GaN-based material layer is formed on the pattern mask. If it is a thing, it will not be limited to the material containing Si.

  The N-plane region (crystal inversion region) 4 of the epitaxial growth layers 3 and 4 shown in FIG. 9 is easily corroded by the alkaline liquid, and the Ga-plane region 3 is not easily corroded. By utilizing this characteristic, only the N-plane region (crystal inversion region) 4 can be selectively removed by wet etching the epitaxial growth layers 3 and 4 with an alkaline solution. As a result, as shown in FIG. 10, the N-plane region 4 of the crystal inversion region becomes a hole (gap) 5, and the holes 5 are regularly arranged in the GaN-based semiconductor layer 3 to form the photonic crystals 3 and 5. Is done. Air will naturally enter the hole 5. Moreover, the gas etc. which generate | occur | produce in a post process may be contained.

  8 to 10 describe the shape of the pattern mask for forming the regularly arranged holes. FIGS. 11 to 13 show the pattern mask for forming the columnar structure regularly arranged in the space (gap). Will be described. FIG. 11 is a diagram showing a pattern mask for forming a columnar structure regularly arranged in the space. A pattern mask having hexagonal holes in a honeycomb shape is formed on the substrate surface 1a. When a GaN-based semiconductor layer is formed on the substrate in the state shown in FIG. 11, a crystal inversion region (N-plane region) 4 is formed in a region corresponding to the honeycomb wall, and a GaN-based semiconductor is formed in a region corresponding to the hexagonal hole in the honeycomb. The semiconductor layer (Ga face region) 3 is epitaxially grown.

  When the substrate in the state of FIG. 12 is wet-etched with an alkaline solution while protecting the back surface, the crystal inversion region (N-plane region) 4 is selectively removed, and the columns 6 as shown in FIG. 13 are regularly arranged in the gap. A columnar structure (triangular lattice arrangement) can be obtained. Although FIG. 13 shows a hexagonal column, it is easy to make a cylinder by only correcting the pattern of FIG. In FIG. 13, the space (gap) 5 between the pillars is a part corresponding to the hole (gap) 5 in FIG. 10, and both of the crystal inversion regions (N-plane regions) 4 formed on the pattern mask are alkaline. It is a portion that has become a space (void) by wet etching with a liquid.

(Production method)
FIG. 14A shows a substrate 1 for producing a photonic crystal. A pattern mask 2 is formed on the substrate 1 as shown in FIG. The pattern shown in FIG. 14B is a pattern mask for forming the hole patterns shown in FIGS. Thereafter, through the respective steps shown in FIGS. 5 to 7, a state in which the crystal inversion regions are two-dimensionally arranged is obtained (see FIG. 7). Next, wet etching is performed using an alkali solution, and as shown in FIG. 14C, the region where the crystal inversion region is present is selectively removed to form a hole or space 5.

  On the other hand, in order to form a light emitting portion, an active layer forming substrate 51 different from the substrate 1 is prepared as shown in FIG. Next, as shown in FIG. 14E, the p-type cladding layer 16, the active layer 15, and the n-type cladding layer 14 are sequentially formed on the active layer forming substrate 51. Between the active layer forming substrate 51 and the p-type cladding layer 16, a carrier block layer and an electrode forming contact layer can be provided. An n-type guide layer can be provided between the n-type cladding layer 14 and the active layer 15, and an n-type buffer layer can be provided in the n-type cladding layer 14. Thereafter, as shown in FIG. 14F, planarization is performed using a planarization method such as polishing in order to eliminate the uneven surface layer 17 of the laminated epitaxial growth layer.

  The substrate in the state of FIG. 14C and the active layer forming substrate in the state of FIG. 14F are bonded to each other with their planarized surfaces facing each other. Bonding can be performed by heating while applying pressure in a heated atmosphere. FIG. 14 (g) is a diagram showing a state after bonding. Thereafter, the active layer forming substrate 51 is removed. Thereafter, as shown in FIG. 1, the anode electrode 21 is formed on the surface of the p-type cladding layer 16, and the cathode electrode 22 is formed on the back surface of the substrate 1, thereby obtaining the semiconductor light emitting device shown in FIG. Can do.

  As shown in FIG. 14G, the light emitting device 10 of the present embodiment includes an active layer 15, and the hole or space 5 on the pattern mask 2 and the GaN-based semiconductor layer 3 have a two-dimensional period with high accuracy. It is arranged. The two-dimensional periodic arrangement of the space 5 and the GaN-based semiconductor layer 3 is “the formation of a mask of a two-dimensional periodic pattern, the crystal inversion region (N-plane region) formed thereon, and the crystal inversion region. It can be obtained by a very simple method of “removal by wet etching”.

  The above (manufacturing method) can be comprehensively described as follows. A method for manufacturing a semiconductor light-emitting element in the present embodiment is a method for manufacturing an element including a structure having a photonic crystal effect, which includes a step of forming a pattern mask of a material layer containing Si on a substrate, Epitaxially growing a GaN-based semiconductor layer to form a crystal inversion region on the pattern mask, flattening the epitaxially grown GaN-based semiconductor layer, and a crystal inversion region formed on the pattern mask And removing with an alkaline solvent. Further, the method according to the present embodiment includes a step of preparing an active layer forming substrate different from the above substrate and sequentially epitaxially growing a plurality of semiconductor layers including the active layer thereon, and a semiconductor layer including the active layer. The substrate and the active layer forming substrate are bonded together with the step of planarizing the upper surface of the substrate and the surface of the flattened GaN-based semiconductor layer of the substrate facing the planarized surface of the active layer forming substrate. A process.

(Embodiment 2)
In Embodiment 1, a surface-emitting type semiconductor light-emitting element has been described, but the present invention may be applied to an edge-emitting type semiconductor light-emitting element.

  15 and 16 are a cross-sectional view and a plan view showing the configuration of the edge-emitting type semiconductor light emitting device in the second embodiment of the present invention. FIG. 17 is a diagram showing the light propagation region 27.

  Referring to FIGS. 15 and 16, pattern mask 2 is formed on the surface of substrate 1 in a predetermined pattern. On the pattern mask 2, an n-type cladding layer 14, an active layer 15, and a p-type cladding layer 16 are sequentially stacked. A hole 5 is formed on the pattern mask 2 so as to penetrate the n-type cladding layer 14, the active layer 15, and the p-type cladding layer 16. The holes 5 are arranged at triangular lattice points when seen in a plan view, and the arrangement of the holes 5 constitutes a photonic crystal. However, as shown in FIG. 17, the hole 5 is not formed in the light propagation region 27. An anode electrode 21 is formed on the light propagation region 27 so as to be electrically connected to the p-type cladding layer 16, and a cathode electrode 22 is formed on the back surface of the substrate 1 so as to be electrically connected to the substrate 1. Is formed. In addition, an antireflection film 25 is formed on the end face serving as the light exit surface.

  The method shown in FIGS. 5 to 10 can be applied to the step of forming the holes 5 in the n-type cladding layer 14, the active layer 15, and the p-type cladding layer 16. That is, referring to FIG. 15, the n-type cladding layer 14, the active layer 15, and the p-type cladding layer 16 are sequentially laminated on the pattern mask 2, so that only the pattern inversion region ( It is possible to form the hole 5 by selectively removing only the crystal inversion region by wet etching with an alkaline solution.

  The wavelength of light emitted from the active layer 15 by applying a positive voltage to the anode electrode 21 and a negative voltage to the cathode electrode 22 is a two-dimensional periodic pattern formed by the holes 5 and the layers 14, 15, 16. The wavelength of the photonic band of the photonic crystal. For this reason, the light generated in the active layer 15 cannot propagate through the photonic crystal and propagates only through the light propagation region 27. For this reason, if the antireflection film 25 is formed on the end face, the light propagating through the light propagation region 27 is emitted outside only through the antireflection film 25.

(Embodiment 3)
FIG. 18 is a diagram for explaining a manufacturing method according to Embodiment 3 of the present invention. FIG. 19 is a diagram showing a film formation base layer 61 formed of a GaN-based semiconductor layer including the crystal inversion region 4. As shown in FIG. 18, in the present embodiment, the layers S ₁ ,... S _N are taken out from the GaN-based semiconductor layer 3 including the crystal inversion region 4 formed using the pattern mask 2, and the film formation base layer 61 and To do. As shown in FIG. 20, GaN-based semiconductor layers 3 and 4 are epitaxially grown on the film-forming base layer 61, and a GaN-based semiconductor layer 62 including the crystal inversion region 4 can be obtained without using a pattern mask. .

  According to the present embodiment, since a GaN-based semiconductor layer including a crystal inversion region can be obtained without using a pattern mask, a semiconductor light emitting element including a photonic crystal structure can be supplied at low cost.

  Next, modified examples or specific examples in the first to third embodiments will be described. In the step of forming the GaN-based material layer including the crystal inversion region, a pattern mask of the material layer containing Si is formed on the substrate, and the GaN-based semiconductor layer is epitaxially grown on the substrate, and the crystal inversion region is formed on the pattern mask. Can be included. By this method, it is possible to easily obtain a pattern in which crystal inversion regions are two-dimensionally arranged, and then easily form a photonic crystal by wet etching.

  In the step of forming the GaN-based material layer including the crystal inversion region, a pattern mask of the material layer containing Si is formed on the substrate, and the GaN-based semiconductor layer is epitaxially grown on the substrate, and the crystal inversion region is formed on the pattern mask. Next, at least a part of the thickness of the epitaxially grown GaN-based semiconductor layer is taken out from the substrate in the form of a layer to form a film-forming base layer, and the GaN-based semiconductor layer is epitaxially grown on the film-forming base layer. A crystal inversion region directly epitaxially grown may be formed on the crystal inversion region of the film forming base layer. A GaN-based semiconductor layer including a crystal inversion region can be easily obtained without using a pattern mask, and then a photonic crystal can be obtained, so that this semiconductor light-emitting element can be provided at low cost.

  Further, in the step of forming the GaN-based material layer including the crystal inversion region, a pattern mask of the material layer including Si is formed on the substrate, and the n-type GaN-based semiconductor layer and the quantum well structure-type GaN-based semiconductor are formed on the substrate. The active layer and the p-type GaN-based semiconductor layer may be epitaxially grown sequentially to form a crystal inversion region for each of these layers on the pattern mask.

  In the wet etching process, the crystal inversion region formed on the pattern mask is preferably removed with an alkaline solvent.

  In the step of sequentially epitaxially growing a plurality of semiconductor layers including the active layer, a p-type GaN-based semiconductor layer, a quantum well structure-type GaN-based semiconductor active layer, and an n-type GaN-based semiconductor layer are sequentially epitaxially grown on the active layer forming substrate. May be. By this method, when the substrate and the active layer forming substrate are bonded together, the n-type conductivity type of the surface layer of the active layer forming substrate matches the n conductivity type of the surface layer of the substrate, so an unnecessary pn junction can be avoided. .

  The method may further include a step of removing at least one of the substrate and the active layer forming substrate and a step of planarizing the surface after the removal in the removing step. By this method, it is possible to realize simplification, miniaturization, and weight reduction of the power supply by reducing the necessary applied voltage and current.

  In addition, a plurality of semiconductor light emitting elements may be formed on the semiconductor surface, and the semiconductor light emitting elements may be further separated into individual pieces. This method can increase the production efficiency and enable mass production.

  The above substrates are a single crystal Si (111) plane substrate, a single crystal GaAs (111) plane substrate (Ga plane substrate), a single crystal GaN (0001) plane substrate, a highly oriented GaN (0001) plane substrate, and sapphire (0001). A substrate selected from the surface substrates may be used. With these substrates, an epitaxial layer can be easily formed while including a crystal inversion region in the GaN-based semiconductor layer.

  The active layer forming substrate includes a single crystal Si (111) plane substrate, a single crystal GaAs (111) plane substrate (Ga plane substrate), a single crystal GaN (0001) plane substrate, and a highly oriented GaN (0001) plane. It is good also as a board | substrate chosen from a board | substrate and a sapphire (0001) surface board. With this configuration, a highly efficient light-emitting layer in the visible region can be obtained using a layer containing a GaN-based semiconductor in the active layer.

  The crystal inversion region is preferably an N-plane orientation (000-1) region existing in a region where the Ga-plane orientation (0001) of the GaN-based material is main. With this configuration, a GaN-based epitaxial layer can be obtained using the N-plane region that can be easily removed by wet etching as the crystal inversion region.

The material layer containing Si may include at least one of SiO ₂ and Si ₃ N ₄ . With this configuration, a pattern mask can be obtained at low cost using an existing semiconductor device manufacturing apparatus.

  The shape of the pattern mask is either a circle or a polygon, and may be arranged in any one of a triangular lattice and a square lattice. Moreover, the shape of the pattern mask may be a lattice arrangement of either a triangular lattice or a tetragonal lattice, and circular and polygonal holes may be opened. In either case, a standard two-dimensional periodic pattern can be easily obtained.

  In the planarization step, at least one of lapping, polishing, wet etching, and dry etching may be used. By this method, a highly accurate flat surface can be obtained without damaging the inside.

  In the step of removing the crystal inversion region by wet etching, a liquid containing at least one of NaOH and KOH can be used. By this method, the N-plane region, which is an inversion region in the GaN-based semiconductor layer, is easily removed, and a space (void) region in which a gas whose refractive index is significantly different from that of the GaN-based material is enclosed is provided at a low cost. Can do.

In Example 1 of the present invention, an edge-emitting type semiconductor light emitting device shown in FIGS. 15 to 17 was manufactured. First, a single crystal n-type GaAs (111) substrate having a diameter of 2 inches was prepared. After cleaning, a SiO ₂ film having a thickness of 0.1 μm was formed on the entire surface of the substrate by sputtering deposition. Next, a pattern mask of a triangular lattice arrangement with a diameter of 0.3 μm and a pitch of 0.5 μm was formed by an exposure technique so that a 3 μm wide portion (light propagation region) 27 was opened (see FIG. 17). An n-type GaN buffer layer, an n-type AlGaN cladding layer 14, an n-type GaN guide layer, an active layer 15 having a quantum well structure made of GaN / InGaN, and a p-type AlGaN are sequentially formed on the pattern mask by using an organic metal CVD method. The clad layer 16 and the p-type GaN contact layer were epitaxially grown.

While protecting the GaAs substrate surface 1b of the substrate with a resist, etching was performed in a 5N KOH alkaline solution for 1 hour. An N-type crystal inversion region 4 is formed at the position of the SiO ₂ pattern mask 2 in the epitaxially grown layer. When the substrate is taken out, a hole (gap) 5 having a diameter of 0.23 μm is formed at a position corresponding to the pattern mask. Was open (see FIG. 10).

On the epitaxial growth surface 1a side of this substrate, a Pt electrode 21 was formed in a region 27 (light propagation region) 27 which was not etched without a pattern mask having a width of 3 μm. An AuGe electrode 22 was formed on the GaAs substrate surface. Thereafter, cleavage was performed in a direction perpendicular to the oscillation surface of the laser, and an antireflection film 25 was formed of Al ₂ O ₃ at the oscillation end.

  When the edge-emitting laser chip manufactured as described above was mounted on an AlN submount and an oscillation test was performed, oscillation at a low threshold could be confirmed.

Also in Example 2 of the present invention, the edge-emitting type semiconductor light emitting device shown in FIGS. 15 to 17 was manufactured. However, the Si substrate 1 is used as the substrate, and the pattern shape is also different. First, a single crystal n-type Si (111) substrate having a diameter of 2 inches was prepared. After cleaning, a Si ₃ N ₄ film having a thickness of 0.1 μm was formed on the entire surface of the substrate by sputtering deposition. Next, a pattern mask 2 having a square lattice arrangement with a diameter of 0.32 μm and a pitch of 0.54 μm was formed by an exposure technique so as to open a width of 2 μm. An n-type GaN buffer layer, an n-type AlGaN cladding layer 14, an n-type GaN guide layer, an active layer 15 having a quantum well structure made of GaN / InGaN, and a p-type electron are sequentially formed on the pattern mask by using an organic metal CVD method. The block layer, p-type AlGaN cladding layer 16 and p-type GaN contact layer were epitaxially grown.

While protecting the back surface 1b of the substrate with a resist, the substrate was etched in a 3N KOH alkaline solution for 3 hours. For the above reason, a hole (void) 5 having a diameter of 0.2 μm was opened in the substrate at the position of the Si ₃ N ₄ pattern mask in the region of the epitaxial layer.

On the epitaxial growth surface 1a side of this substrate, a Pt electrode 21 was formed in a region (light propagation region) 27 that had no pattern mask with a width of 2 μm and was not etched. An Al electrode 22 was formed on the back surface 1b of the Si substrate. Thereafter, cleavage was performed in a direction perpendicular to the oscillation surface of the laser, and an antireflection film 25 was formed at the oscillation end with a laminated structure of Al ₂ O ₃ and SiO ₂ .

  When the edge-emitting laser chip manufactured as described above was mounted on an AlN submount and an oscillation test was performed, oscillation at a low threshold could be confirmed.

In Example 3 of the present invention, an edge-emitting type semiconductor light emitting device shown in FIG. 1 or FIG. 14G was manufactured. First, a highly oriented n-type GaN (0001) substrate 1 having a diameter of 50 mm was prepared. A SiO ₂ film was formed to a thickness of 0.1 μm by sputtering deposition on the Ga type crystal face 1a of this substrate. An exposure technique was used for this SiO ₂ thin film to form a pattern mask 2 arranged in a triangular lattice with an aperture diameter of 0.2 μm and a pitch of 0.5 μm.

An n-type GaN layer 3 including a crystal inversion region (N-plane region) 4 was epitaxially grown on the pattern mask 2 by a thickness of 0.3 μm by using an organic metal CVD method. This epitaxial growth surface was flattened to an RMS of 10 mm (1 nm) by polishing. At this time, the thickness of the epitaxial growth layer was 0.15 μm. In order to remove the processing damage on the polished surface, the surface was processed for 1 minute by RIE using chlorine gas. The back surface (N-type crystal surface of the GaN substrate) 1b of this substrate was protected with a resist and immersed in a 5N KOH alkaline solution for about 2 hours. As a result, only the N-type crystal region 4 formed on the SiO ₂ pattern mask 2 was selectively etched to form a columnar structure having a diameter of 0.18 μm and a height of 0.15 μm.

  Next, a sapphire substrate (see FIG. 14D) of the active layer forming substrate 51 is prepared, and a p-type GaN contact layer, a p-type AlGaN cladding layer 14, and a p-type AlGaN electron are sequentially formed by using an organic metal CVD method. A block layer, an active layer 15 having a quantum well structure made of GaN / InGaN, an n-type GaN guide layer, an n-type AlGaN cladding layer 16 and an n-type GaN buffer layer were epitaxially grown. The n-type GaN buffer layer was flattened to RMS 12 mm (1.2 nm) by lapping and polishing. Thereafter, in order to remove the processing damage, the surface was processed for 1 minute by RIE using a chlorine-based gas.

  The planarized surface of the GaN substrate 1 (see FIG. 14C) on which the columnar structure was previously formed and the sapphire substrate 51 (see FIG. 14F) face each other, and the surface was exposed to nitrogen plasma. . Thereafter, the surfaces were brought into contact with each other in a vacuum, and were pressed and bonded to each other while heating to 750 ° C. (see FIG. 14G). Since the sapphire substrate 51 becomes unnecessary, the sapphire substrate 51 was removed while maintaining a flat surface by the RIE method. A Pt substrate 21 and a 0Ti / Al electrode 22 were formed on the exposed p-type GaN contact layer and on the back surface 1b of the n-type GaN substrate, respectively.

  When the surface-emitting type GaN-based semiconductor light-emitting device was mounted on an AlN submount and energized, light emission at a low threshold could be confirmed.

Also in Example 4 of the present invention, an edge-emitting type semiconductor light emitting device shown in FIG. 1 or FIG. First, a square highly oriented n-type GaN (0001) substrate 1 having a side of 30 mm was prepared. A Si ₃ N ₄ film having a thickness of 0.12 μm was formed on the Ga-type crystal surface of this substrate by sputtering deposition. An exposure technique was used for this Si ₃ N ₄ thin film to form a pattern mask 2 arranged in a square lattice with an aperture diameter of 0.27 μm and a pitch of 0.52 μm.

An n-type GaN 3 layer including a crystal inversion region (N-plane region) 4 was epitaxially grown on the pattern mask by a thickness of 0.32 μm by using an organic metal CVD method. This epitaxial growth surface was flattened to an RMS of 10 mm (1 nm) by polishing. At this time, the thickness of the epitaxial growth layer was 0.18 μm. In order to remove the processing damage on the polished surface, the surface was processed for 1 minute by RIE using chlorine gas. The back surface of the substrate (N-type crystal surface of the GaN substrate) was protected with a resist and immersed in a 5N KOH alkaline solution for about 2.5 hours. As a result, only the N-type crystal region 4 formed on the Si ₃ N ₄ pattern mask was selectively etched to form a hole structure having a diameter of 0.23 μm and a depth of 0.15 μm.

  Next, similarly, a rectangular highly oriented n-type GaN (0001) substrate 51 having a side of 30 mm is prepared (see FIG. 14D), and a p-type GaN contact layer and a p-type are sequentially formed by using an organic metal CVD method. Epitaxial growth of an AlGaN / GaN superlattice cladding layer 14, a p-type AlGaN electron block layer, an active layer 15 having a quantum well structure made of GaN / InGaN, an n-type GaN guide layer, an n-type AlGaN cladding layer 16, and an n-type GaN buffer layer I let you. The n-type GaN buffer layer was planarized to RMS 11 mm (1.1 nm) by lapping and polishing. Thereafter, in order to remove the processing damage, the surface was processed for 1 minute by RIE using a chlorine-based gas.

  The planarized surface of the GaN substrate (see FIG. 14C) on which the hole structure has been previously formed and the n-type GaN substrate 51 (see FIG. 14F) face each other, and the surface is exposed to nitrogen plasma. did. Thereafter, the surfaces were brought into contact with each other in a vacuum, and were pressed and bonded to each other while heating to 750 ° C. (see FIG. 14G). Since the GaN substrate 51 on which the active layer 15 is formed is unnecessary, the GaN substrate 51 is removed while maintaining a flat surface by the RIE method. A Pt substrate 21 and a Ti / Al electrode 22 were formed on the exposed p-type GaN contact layer and on the back surface 1b of the n-type GaN substrate, respectively.

  When the GaN-based semiconductor light-emitting device was mounted on an AlN submount and energized, light emission at a low threshold could be confirmed.

  As described above, in any of the semiconductor light emitting devices of the examples of the present invention, it was confirmed that a photonic crystal structure was formed by a very simple method and light was emitted at a threshold lower than usual.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  According to the present invention, the crystal inversion region can be formed in the GaN-based semiconductor layer based on the unique manufacturing method, and the crystal inversion region can be easily removed by wet etching, so that the two-dimensional period between the space and the GaN-based semiconductor layer is obtained. A photonic crystal composed of a pattern can be formed. And the semiconductor light-emitting device containing the photonic crystal can be provided easily. For this reason, it is expected to make a great contribution in many devices using light in the future.

It is sectional drawing which shows the semiconductor light-emitting device in Embodiment 1 of this invention. FIG. 2 is a plan view of the semiconductor light emitting device of FIG. 1. It is a figure which shows the state before dividing the semiconductor light-emitting device of FIG. 2 into pieces. It is a schematic diagram of the crystal structure of GaN in Embodiment 1 of the present invention. It is a figure which shows the state which formed the pattern mask in the substrate surface. It is a figure which shows the state after carrying out the epitaxial growth of the GaN-type semiconductor layer. It is a figure which shows the state which planarized. It is a figure which shows the state which formed the pattern mask for forming a hole structure in the substrate surface. It is a figure which shows the state which epitaxially grown the GaN-type semiconductor layer containing a crystal inversion area | region. It is a figure which shows the state which removed the N surface area | region of the crystal inversion area | region by wet etching, and formed the hole structure. It is a figure which shows the state which formed the pattern mask for forming columnar structure in the substrate surface. It is a figure which shows the state which epitaxially grown the GaN-type semiconductor layer containing a crystal inversion area | region. It is a figure which shows the state which removed the N surface area | region of the crystal inversion area | region by wet etching, and formed the columnar structure. 2A and 2B are diagrams illustrating a method for manufacturing the semiconductor light emitting device of FIG. 1, in which (a) a substrate for forming a photonic crystal, (b) a pattern mask is formed, (c) a crystal inversion region (N-plane by wet etching) (Region) is removed, (d) active layer forming substrate, (e) a stacked structure including the active layer, (f) planarized state, (g) photonic crystal forming substrate and active layer The state which bonded the formation board | substrate together is each shown. It is sectional drawing which shows the semiconductor light-emitting device in Embodiment 2 of this invention. FIG. 16 is a plan view of the semiconductor light emitting device of FIG. 15. It is a figure for demonstrating the light propagation of the semiconductor light-emitting device of FIG. It is a figure which shows the manufacturing method of the semiconductor light-emitting device in Embodiment 3 of this invention. It is a figure which shows the film-forming base layer obtained by the manufacturing method demonstrated in FIG. It is a figure which shows the state which grew the GaN-type semiconductor layer epitaxially on the film-forming base layer.

Explanation of symbols

1 substrate (for photonic crystal formation), 1a substrate surface, 1b substrate back surface, 2 pattern mask, 3 GaN-based semiconductor layer (Ga surface region), 4 crystal inversion region (N surface region), 5 hole (void), 6 Pillar, 10 Semiconductor light emitting element, 14, 16 Clad layer, 15 Active layer, 17 Concavity and convexity surface layer, 21, 22 Electrode, 25 Antireflection film, 27 Light propagation region, 51 Substrate for forming active layer, 61 Base layer for forming film, 62 GaN-based semiconductor layer on film formation base layer, S ₁ ,..., _SN film formation base layer.

Claims (21)

  A method of manufacturing an element including a structure having a photonic crystal effect, comprising: a step of forming a GaN-based material layer including a crystal inversion region; and a step of removing the crystal inversion region by wet etching. Device manufacturing method.   In the step of forming the GaN-based material layer including the crystal inversion region, a pattern mask of a material layer containing Si is formed on the substrate, and then a GaN-based semiconductor layer is epitaxially grown on the substrate to at least a part of the pattern mask. The method of manufacturing a semiconductor light emitting device according to claim 1, wherein a crystal inversion region is formed in the semiconductor light emitting device.   In the step of forming the GaN-based material layer including the crystal inversion region, a pattern mask of a material layer containing Si is formed on the substrate, and then a GaN-based semiconductor layer is epitaxially grown on the substrate to at least a part of the pattern mask. A crystal inversion region is formed, and at least a part of the thickness of the epitaxially grown GaN-based semiconductor layer is taken out from the substrate in a layer form and used as a film formation base layer, and the GaN layer is formed on the film formation base layer. 2. The method for manufacturing a semiconductor light emitting element according to claim 1, wherein a crystal inversion region is formed directly on the crystal inversion region of the film forming base layer by epitaxially growing a system semiconductor layer. 3.   In the step of forming the GaN-based material layer including the crystal inversion region, a pattern mask of a material layer including Si is formed on the substrate, and an n-type GaN-based semiconductor layer and a quantum well structure-type GaN-based semiconductor active layer are formed on the substrate. 2. The method of manufacturing a semiconductor light emitting device according to claim 1, wherein a p-type GaN-based semiconductor layer is epitaxially grown sequentially so that a crystal inversion region of each of these layers is formed on at least a part of the pattern mask.   5. The method of manufacturing a semiconductor light emitting element according to claim 1, wherein in the wet etching step, a crystal inversion region formed in at least a part on the pattern mask is removed with an alkaline solvent. A method of manufacturing an element including a structure having a photonic crystal effect,
Forming a pattern mask of a material layer containing Si on a substrate;
A step of epitaxially growing a GaN-based semiconductor layer on the substrate to form a crystal inversion region in at least a part of the pattern mask;
Planarizing the epitaxially grown GaN-based semiconductor layer;
Removing the crystal inversion region on the pattern mask with an alkaline solvent;
A step of preparing an active layer forming substrate different from the substrate and sequentially epitaxially growing a plurality of semiconductor layers including the active layer on the active layer forming substrate;
Planarizing the upper surface of the semiconductor layer including the active layer;
A step of bonding the substrate and the active layer forming substrate to each other so that the surface of the flattened GaN-based semiconductor layer of the substrate faces the flattened surface of the active layer forming substrate. Device manufacturing method.   In the step of sequentially epitaxially growing a plurality of semiconductor layers including the active layer, a first conductivity type GaN-based semiconductor layer, a quantum well structure type GaN-based semiconductor active layer, and a second conductivity type are formed on the active layer forming substrate. The method for manufacturing a semiconductor light emitting device according to claim 6, wherein the GaN-based semiconductor layers are epitaxially grown sequentially.   The method of manufacturing a semiconductor light-emitting element according to claim 6, further comprising a step of removing at least one of the substrate and the substrate for forming an active layer, and a step of flattening a surface after being removed in the removal step. Method.   The method for manufacturing a semiconductor light emitting element according to claim 1, further comprising a step of forming a plurality of the semiconductor light emitting elements on a semiconductor surface and dividing the plurality of semiconductor light emitting elements into pieces.   The substrate is selected from a single crystal Si (111) plane substrate, a single crystal GaAs (111) plane substrate, a single crystal GaN (0001) plane substrate, a highly oriented GaN (0001) plane substrate, and a sapphire (0001) plane substrate. The method for manufacturing a semiconductor light emitting device according to claim 2, wherein the semiconductor light emitting device is a substrate.   The active layer forming substrate includes a single crystal Si (111) plane substrate, a single crystal GaAs (111) plane substrate, a single crystal GaN (0001) plane substrate, a highly oriented GaN (0001) plane substrate, and a sapphire (0001) plane substrate. The manufacturing method of the semiconductor light-emitting device according to any one of claims 6 to 10, which is a substrate selected from among the above.   12. The crystal inversion region according to claim 1, wherein the crystal inversion region is a region of an N-plane orientation (000-1) of a GaN-based material, and is disposed in a region mainly having a Ga-plane orientation (0001). The manufacturing method of the semiconductor light-emitting device of description. The method for manufacturing a semiconductor light-emitting element according to claim 2, wherein the material layer containing Si includes at least one of SiO ₂ and Si ₃ N ₄ .   The manufacturing of the semiconductor light-emitting element according to claim 2, wherein a shape of the pattern mask is one of a circle and a polygon, and the pattern mask is arranged in any one of a triangular lattice and a square lattice. Method.   14. The semiconductor light emitting element according to claim 2, wherein the pattern mask has a lattice arrangement of any one of a triangular lattice and a square lattice, and holes having a circular shape and a polygonal shape are opened. Production method.   The method for manufacturing a semiconductor light emitting element according to claim 2, wherein at least one of lapping, polishing, wet etching, and dry etching is used in the planarization step.   The method for manufacturing a semiconductor light emitting element according to claim 1, wherein a liquid containing at least one of NaOH and KOH is used in the step of removing the crystal inversion region by wet etching. A light emitting device including a GaN-based semiconductor layer,
Having a pattern mask of a two-dimensional periodic pattern;
A semiconductor light emitting device, wherein a substance having a refractive index different from that of the GaN-based semiconductor layer is disposed on the pattern mask so as to form a two-dimensional periodic array with the GaN-based semiconductor layer. The semiconductor light emitting element according to claim 18, wherein the pattern mask is formed of at least one of SiO ₂ and Si ₃ N ₄ . A light-emitting element formed on a film-forming base layer,
The film-forming base layer is an epitaxially grown GaN-based semiconductor layer including crystal inversion regions arranged two-dimensionally,
The epitaxially grown GaN-based semiconductor layer on the film-forming base layer and a substance having a refractive index different from that of the GaN-based semiconductor layer located on the crystal inversion region in the film-forming base layer An array of semiconductor light emitting devices.   21. The semiconductor light emitting element according to claim 18, wherein the substance having a refractive index different from that of the GaN-based semiconductor layer is a gas sealed in a gap.

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